http://informahealthcare.com/gye ISSN: 0951-3590 (print), 1473-0766 (electronic) Gynecol Endocrinol, 2014; 30(4): 266–271 ! 2014 Informa UK Ltd. DOI: 10.3109/09513590.2013.871525
OVARIAN CANCER
Micro-RNAs and ovarian cancer: the state of art and perspectives of clinical research Angiolo Gadducci, Claudia Sergiampietri, Nora Lanfredini, and Ilaria Guiggi
Abstract
Keywords
Dysregulation of microRNA (mi-RNA) expression plays a major role in the development and progression of most human malignancies. Members of the miR-200 family, miR-182, miR-214 and miR-221 are frequently up-regulated, whereas miR-100, let-7i, miR-199a, miR-125b, mir-145 and miR-335 are often down-regulated in ovarian cancer compared with normal ovarian tissue. Most mi-RNA signatures are overlapping in different tumor histotypes but some mi-RNAs seem to be histotype specific. For instance, the endometrioid type shares with the serous and clear cell types the up-regulation of miR-200 family members, but also presents over-expression of miR-21, miR-202 and miR-205. Clear cell carcinoma has a significantly higher expression of miR30a and miR-30a*, whereas mucinous histotype has elevated levels of miR-192/194. In vitro and in vivo investigations have shown that several mi-RNAs can modulate the sensitivity of ovarian cancer to platinum and taxane, and clinical studies have suggested that mi-RNA profiling may predict the outcome of patients with this malignancy. Some mi-RNAs could be used as biomarkers to identify patients that might benefit from the addition of molecularly targeted agents (i.e. anti-angiogenic agents, MET inhibitors and poly(ADP-ribose) polymerase (PARP) inhibitors) to standard chemotherapy. Moreover, mi-RNAs could represent potential targets for the development of novel therapies.
Biomarkers, chemoresistance, micro-RNAs, ovarian cancer, prognosis
Introduction MicroRNAs (mi-RNAs) are small non-coding single-stranded RNAs that negatively regulate gene expression and are involved in the regulation of key cellular processes such as cell cycle, differentiation and apoptosis [1,2]. Human genoma encodes approximately 1000 mi-RNAs able to regulate up to 60% of all transcriptome [3]. Mi-RNA primary transcripts are first released and then processed by the RNase III-type endonucleases Drosha and Dicer to produce mature mi-RNAs of 21–22 nucleotides [4]. Fully-processed mi-RNAs associate with the Argonaute proteins within the effector complex termedas a RNA-induced silencing complex (RISC). RISC binds to the 30 -untranslated region (UTR) of the target mRNA in a sequence-specific manner, and down-regulates gene expression through either inhibition of translation or increased degradation of RNA. Mi-RNA activity is characterized by redundancy, since each mi-RNA regulates hundreds or thousands of targets and different mi-RNAs may also repress the same target ([2]. Dysregulation of mi-RNA expression plays a major essential role in tumorigenesis [5–7]. It is noteworthy that same mi-RNAs can act as an oncogene in one cell type and as a tumor suppressor in another one because of different targets and mechanisms of action [5]. For instance, miR222/221 cluster is over-expressed in breast, lung or liver cancers where targets are tumor suppressor genes such as PTEN, p27 and
Address for correspondence: Angiolo Gadducci, Clinical and Experimental Medicine, Division of Gynecology and Obstetrics, University of Pisa, Via Roma 56, Pisa, 56127, Italy. Tel: 39 50 992609. Fax: 39 50 553410. E-mail: [email protected]
History Received 24 October 2013 Revised 29 October 2013 Accepted 29 November 2013 Published online 30 January 2014
p57, while the same cluster is down-regulated in erythroblastic leukemia where target is c-KIT oncogene [8].The application of the high-throughput technologies has allowed the identification of cancer-specific mi-RNA fingerprints in all human cancers, and the patterns of mi-RNA expression may provide useful information for tumor classification and prognosis [5,6]. The present paper has reviewed the literature data about the relevance of mi-RNAs for the pathogenesis, the response to chemotherapy and the prognosis of ovarian cancer.
Altered mi-RNA expression and ovarian carcinogenesis
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Department of Clinical and Experimental Medicine, Division of Gynecology and Obstetrics, University of Pisa, Pisa, Italy
Members of the miR-200 family (miR-200a, miR-200b, miR200c, miR-141), miR-182, miR-214 and miR-221 are frequently up-regulated, whereas miR-100, let-7i, miR-199a, miR-125b, mir145 and miR-335 are often down-regulated in ovarian cancer compared with normal ovarian tissue [9–18] (Table 1). miR-200a and miR-200b are located on chromosome 1, while miR-200c and miR-141 are placed on chromosome 12 [19]. miR200a, miR-200b, miR-200c and miR-141 have BRCA1-associated protein [BAP-1] as common target, that is down-modulated in ovarian cancer [9]. Other prominent targets of the miR-200 family are two E-box binding transcription factors, termed ZEB1 and ZEB2, involved in a complex network of transcriptional repressors regulating E-cadherin expression and epithelial polarity [19,20]. Moreover, miR-200 family is a powerful regulator of the epithelial-to-mesenchymal transition [EMT], a reversible embryonic program aberrantly activated in tumor progression [21]. Another target of this family is class III b-tubulin (TUBB3), which is over-expressed in several malignancies such as ovarian cancer [22–25].
Micro-RNAs and ovarian cancer
DOI: 10.3109/09513590.2013.871525
Table 1. Micro-RNA altered in ovarian cancer. Micro-RNA Upregulated miR-200 famiy (miR-200a, miR-200b, miR-200c, miR-141) miR-182 miR-214 miR-221 Downregulated miR-100 let-7 family
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miR-199a miR-125b miR-145 MiR-335
Potential targets BAP-1, ZEB1, ZEB2, TUBB3 BRCA1, MTSS1, HMGA2 PTEN c-kit, p27kip1 AKT/m-TOR, Plk-1 KRAS, HMGA2, c-Myc, CDC25A, CDK6, CDK4, cyclin A, cyclin D, cyvlin D2, cyclin D3 HIF-1a, VEGF HIF-1a, VEGF c-myc Blc-w
Yang et al. [13] found that 36 out of 515 mi-RNAs showed differential expression between normal ovarian surface epithelial cells and ovarian cancer. In particular, elevated levels of miR-214 and miR-200a were found in 56% and 43%, respectively, of ovarian carcinomas and were especially associated with highgrade and advanced disease, whereas 76% of these tumors showed down-regulated miR-100. miR-214 enhances cell survival through targeting the 30 -UTR of the PTEN, which leads to PTEN downregulation and activation of Akt-mTOR pathway. Inhibition of Akt with a specific inhibitor or the introduction of PTEN cDNA lacking 3’-UTR abrogates miR-214-induced cell survival. Using mi-RNA profiling analysis, Liu et al. [26] found that miR-182 expression was significantly higher in serous tubal intraepithelial carcinoma, a precursor of high-grade serous ovarian cancer, than in matched normal Fallopian tube, and that miR-182 was significantly over-expressed in most high-grade serous ovarian carcinomas. The oncogenic properties of miR-182 are mediated in part by its impaired repair of DNA double-strand breaks and negative regulation of BRCA1 and metastasis suppressor 1 (MTSS1) expression as well as its positive regulation of the oncogene high-mobility group AT-hook 2 [HMGA2]. Dahiya et al. [14] determined mi-RNA expression profiles in 34 ovarian cancer tissues, in 10 ovarian cancer cell lines, and in an immortalized human ovarian surface epithelium cell line as control. miR-221 was the most highly elevated mi-RNA in both tissues and cancer cell lines (9-fold and 7-fold, respectively), while miR-21 was significantly decreased in both sample types (3-fold and 9-fold, respectively). miR-221 targets c-KIT [27] and p27kip1 [28], whereas miR-21 could modulate tumorigenesis through regulation of BCL2 [29], PTEN [30] and programed cell death 4 [PDCD4] [31]. miR-100 has been reported to be down-regulated in five profiling studies and up-regulated in only one [9,11–14,32]. The transfection of SKOV-3 ovarian cancer cells with pre-miR-100 and anti-miR-100 showed that cell viability could be inhibited by upregulation of miR-100, and could be promoted by down-regulation of this mi-RNA [33]. Over-expression of miR-100 inhibited AKT/ m-TOR signaling pathway and enhanced sensitivity of human ovarian clear cell lines to the rapamycin analog everolimus [34]. MiR-100 may also function as a tumor suppressor by targeting Polo-like kinase 1 (Plk1), a serine/threonine kinase that is involved in the mitosis regulation [35] and that is over-expressed in different malignancies including ovarian cancer [36]. miR-145 has been found to inhibit proliferation and to promote apoptosis in OVCAR-3 and SKOV-3 ovarian cancer cell lines by targeting c-Myc [37].
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The let-7 family, one of the first mi-RNA families shown to be involved in human cancer, inhibits many oncogenic proteins, such as KRAS [38], HMGA2 [39] and c-Myc [40]. In addition, let-7i targets multiple cell cycle-associated genes, including CDC25A, CDK6, CDK4, cyclin A, cyclin D1, cyclin D2 and cyclin D3 [41]. Wang et al. [42] observed that cell proliferation of the ovarian cancer cell lines A2780 and 2008 was significantly reduced after 72 h from the transfection with a let-7 b mimic. miR-199a and miR-125b were found to be down-regulated in ovarian cancer tissues and in the cell lines A2780 and OVCAR-3 [10]. The ectopic expression of miR-199a or miR-125b inhibited tumor angiogenesis both in vitro and in vivo. Over-expression of miR-199a/125b dramatically down-regulated hypoxia-inducible factor-1a (HIF-1a) protein and vascular endothelial growth factor (VEGF) mRNA levels, suggesting that these mi-RNAs exerted an anti-angiogenic effect by decreasing the expression of HIF-1a and VEGF. Cao et al. [15] reported that miR-335 was down-regulated in four ovarian cancer cell lines compared with normal ovarian epithelium tissues. In vitro over-expression of miR-335 suppressed cell migration and invasion, but exhibited a negligible effect on cell proliferation. B-cell CLL/lymphoma 2 like 2 (Bclw), a pro-survival member of the Bcl-2 family, was identified as a potential target of miR-335. The expression of Bcl-w and its effector matrix metalloproteinase (MMP)-2 was down-regulated after transfection with miR-335 mimics, whereas ectopic Bcl-w abrogated the effect of miR-335 over-expression on ovarian cancer cell migration and invasion. In an orthotopic xenograft mouse model, the expression of miR-138 inhibited ovarian cancer spread to other organs [43]. miR-138 directly targeted SRY-related high mobility group box 4 (SOX4) and HIF-1a, and over-expression of SOX4 and HIF-1a reversed the miR-138-mediated suppression of cell invasion. These data supported a novel potential therapeutic strategy for ovarian cancer. Experimental studies on serous ovarian cancer showed that miR-506 increased E-cadherin expression, inhibited cell migration and invasion, and prevented TGFb-induced EMT by targeting SNAI2, a transcriptional repressor of E-cadherin. Nanoparticle delivery of miR-506 in orthotopic ovarian cancer mouse models resulted in E-cadherin accumulation and tumor growth suppression.
Mi-RNA and ovarian cancer: relationship with pathological features Iorio et al. [9], who assessed the genome-wide mi-RNA expression profiling in 84 frozen normal and malignant ovarian tissues, found that most mi-RNA signatures were overlapping in different tumor histotypes but that a number of mi-RNAs seemed to be histotype specific. For instance, the endometrioid type shared with the serous and clear cell types the up-regulation of miR-200a, miR-200b, miR-200c and miR-141, but also presented over-expression of miR-21, miR-202 and miR-205. miR-125b1, miR199a and miR-140 were down-modulated in serous, clear cell and endometrioid carcinomas, miR-145 was down-regulated in both serous and clear cell carcinomas, miR-222 was downmodulated in both endometrioid and clear cell carcinomas, and miR-212 was down-regulated in serous carcinoma. miR-145 is predicted to target c-SRK, MMP-13, and fibroblast growth factor2 (FGF2) [9], miR-222 targets c-Kit [44], and miR-212 targets WT1 [45] and BRCA1 [46] that is often involved also in the pathogenesis of sporadic high-grade serous ovarian cancer. An Italian investigation on 257 frozen specimens from stage I ovarian cancer detected that clear cell carcinoma had a five-fold higher expression of miR-30a and miR-30a*, whereas mucinous histotype had five-fold higher levels of miR-192/194 [47].
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The analysis of 171 formalin-fixed, paraffin-embedded ovarian tissue samples revealed a different expression of miR-30c, miR30d, miR-30e-3p and miR-370 between carcinomas and benign ovarian tissues as well as between carcinomas and borderline tumors [48]. Moreover, miR-181d, miR-30a-3p, miR-532-5p were significantly different between carcinoma and borderline tissues. Among ovarian carcinomas, the expression of miR-30a-3p, miR30c, miR-30d, miR-30e-3p was lowest in mucinous and highest in clear cell histotype, the expression of miR-30a-3p was higher in well-differentiated compared with poorly differentiated tumors, and the expression of miR-370 was higher in early compared with advanced stages. Zhang et al. [12], who assessed 106 human ovarian cancer specimens, found that the expression of several mi-RNAs was significantly different between early and advanced disease, and that mi-RNA alterations mainly consisted in down-regulation in advanced stages. According to histological grade, 13 mi-RNAs exhibited significant differences and all were down-regulated in high-grade compared with the low-grade disease. On the other hand, no significant difference in mRNA levels and immunohistochemical expression of Drosha and Dicer was found between early and advanced disease. Conversely Merritt et al. [49], who analyzed 111 ovarian cancer specimens, observed that low Dicer expression was associated with advanced stage (¼0.007), whereas low Drosha expression was related with suboptimal surgical cytoreduction (p ¼ 0.02). Vaksman et al. [50] assessed Drosha, Dicer, Argonaute 1 and Argonaute 2 mRNA in 144 ovarian cancer specimens (82 effusions, 33 primary tumors and 29 metastases). Significantly elevated levels of all four mRNAs were detected in effusions compared with primary carcinomas (p50.001 to p ¼ 0.006), whereas Argonaute 2 mRNA (p ¼ 0.002) and Drosha mRNA (p ¼ 0.009) were over-expressed in metastases compared with primary tumors. Higher mRNA levels of Dicer (p ¼ 0.003), Drosha (p ¼ 0.01) and Argonaute 1 (p ¼ 0.01) were associated with high-grade histology in primary carcinomas. Elevated Argonaute-2 m-RNA levels in prechemotherapy effusions were an independent prognostic variable for poor progression-free survival (p ¼ 0.046). The different expression of Drosha, Dicer, Argonaute 1,and Argonaute 2 in metastatic sites compared with primary tumors could suggest an involvement of these molecules in ovarian cancer progression.
Mi-RNA and sensitivity to chemotherapy Several in vitro and in vivo investigations have shown that expression of some mi-RNAs can modulate the sensitivity of ovarian cancer to chemotherapeutic agents (Table 2). miR-152 and miR-185 have been found to be significantly down-regulated in the cisplatin-resistant ovarian cancer cell lines SKOV-3/DDP and A2780/DDP compared with their sensitive parent lines SKOV-3 and A2780, respectively [51]. The over-expression of miR-152 or miR-185 increased cisplatin sensitivity by DNA methyltransferase-1 (DNMT-1) suppression. Nude mice intraperitoneally injected with SKOV-3/DDP cells transfected with miR152 mimics showed a better response to cisplatin. The over-expression of miR-93, targeting PTEN, increased the ratio of phosphorylated Akt/total Akt and enhanced the development of cisplatin resistance in the cell lines OVCAR-3 and SKOV-3 [52]. Similarly, miR-214 appeared to induce cisplatin resistance primarily through targeting the PTEN/Akt/m-Tor pathway [53]. Infact, the inhibition of Akt with a small molecule named Akt/protein kinase B signaling inhibitor-2 (API-2) or the introduction of PTEN cDNA lacking 3’-UTR largely abrogated miR-214-induced cell survival. Over-expression of miR-125b caused a marked inhibition of cisplatin-induced cytotoxicity and
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Table 2. Micro-RNA and sensitivity to chemotherapy. Micro-RNA
Target
#miR-152 #miR-185 "miR-93 "miR-214 "miR-125b #let-7i "miR-182
DNMT-1 DNMT-1 PTEN PTEN/AKT/m-Tor BAK-1 RAS, HMGA2, c-myc, CDC25A, CDK6, Cyckin D2 PDCD4
"miR-106a #miR-591 #miR-200c #miR-31 "has-miR 107 "has-miR 222
BLC10, caspase 7 ZEB1 TUBB3 HGF/c-MET RAD51 RAD51
Chemotherapy Cisplatin Cisplatin Cisplatin Cisplatin Cisplatin Cisplatin
resistance resistance resistance resistance resistance resistance
Cisplatin and paclitaxel resistance Paclitaxel resistance Paclitaxel resistance Paclitaxel resistance Paclitaxel resistance PARP inhibitor sensitivity PARP inhibitor sensitivity
apoptosis in OV2008 and C13* cells through down-regulation of the pro-apoptotic Bcl-2 antagonist killer 1 (BAK-1) [54]. The analysis of frozen specimens from 69 advanced ovarian cancer patients revealed that let-7i was expressed at significantly lower levels in the non-complete responders than in complete responders to first-line platinum-based chemotherapy (p ¼ 0.003) [55]. Both loss-of-function (by synthetic let-7i inhibitor) and gainof-function (by retroviral over-expression of let-7i) studies confirmed that reduced let-7i expression significantly increased the resistance to cisplatin. A chimera that combined MUC1 aptamer and let-7i was delivered into OVCAR-3 cells and the released let-7i significantly sensitized tumor cells to paclitaxel, which consequents cell proliferation arrest, apoptosis induction, and decreased survival [56]. The growing advances in oligonucleotide/nanoparticle technologies could allow to use let-7i as a new therapeutic target for ovarian cancer treatment [55]. Enhancer of zeste homologue 2 (EZH2), that encodes a histone methyltransferase, is involved in cancer development and progression through epigenetic gene silencing and chromatin remodeling [57]. EZH2 was found to be over-expressed in cisplatin-resistant ovarian cancer cells, and knockdown of EZH2 by RNA interference resensitized resistant cells to this chemotherapeutic agent [58]. Moreover, loss of EZH2 enhanced sensibility of tumor xenografts to cisplatin and inhibited tumor growth in vivo. Kuang et al. [59] demonstrated that the expression of Dicer was significantly decreased in cisplatin-resistant A2780/ DDP cells and that EZH2 depletion by short hairpin RNA increased the expression of Dicer in vitro, thus suggesting a critical role for EZH2 in the regulation of this endonuclease. Wang et al. [60] found that miR-182 was up-regulated and PDCD4 was down-regulated in ovarian cancer tissues and cell lines and that the increase or blocking of miR-182 led to an opposite alteration of PDCD4. In vitro studies of miR-182 blockage suppressed whereas miR-182 mimics enhanced viability and colony formation of ovarian cancer cells. Moreover, miR-182 reduced cell sensitivity to cisplatin and paclitaxel, probably through its anti-apoptosis activity. Up-regulation of miR-106a and down-regulation of miR-591 were detected to be associated with paclitaxel resistance in ovarian cancer cells and tumor samples [61]. Transfection with anti-miR-106a or pre-miR-591 resensitized resistant cells to paclitaxel. ZEB1 is a target gene of miR591, whereas BCL10 and caspase-7 are target genes of miR-106a. The expression of miR-200c, a regulator of TUBB3, correlated with chemoresistance in a panel of ovarian cancer cell lines [62]. In a xenograft model, miR-200c reduced tumor burden and increased sensitivity to paclitaxel. Low tumor miR-200 expression
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DOI: 10.3109/09513590.2013.871525
was significantly associated with high TUBB3 protein content in a series of 72 ovarian carcinomas [63]. It is noteworthy that noncomplete responders had lower miR-200c levels than complete responders to paclitaxel-based chemotherapy (p ¼ 0.037). Mitamura et al. [64] reported that miR-31 was down-regulated in the paclitaxel-resistant KFr13Tx ovarian cancer cells, and that re-introduction of miR-31 re-sensitized them to paclitaxel both in vitro and in vivo. miR-31 binds to the 3’-UTR of mRNA of the hepatocyte growth factor (HGF) receptor tyrosine kinase MET. HGF/c-MET pathway has a prominent role in mediating antiapoptotic signals through the activation of a phosphatydi-inosotolkinase (PIK)-3/AKT-dependent mechanism [65]. Co-treatment of paclitaxel-resistant cells with MET inhibitors sensitized tumor cells to paclitaxel [64]. Multikinase inhibitors suppressing MET and VEGFR activity have been reported to inhibit proliferation and metastasis of ovarian cancer [66]. Clinical investigations are strongly warranted to assess whether poor responders to chemotherapy might be rescued by a combination of standard chemotherapy with MET inhibitors. Poly(ADP-ribose) polymerase (PARP) inhibitors are effective in killing cells deficient in HR, such as those bearing BRCA1-2 mutations. Neijenhuis et al. [67] found that hsa-miR-107 and hsamiR-222 sensitize tumor cells to the PARP inhibitor olaparib, by repressing the expression of RAD51 and impairing the double strand break repair by HR. Elevated expression of hsa-miR-107 has been detected in a subset of ovarian clear cell carcinomas. These mi-RNAs could be used as biomarkers to identify patients that may benefit from treatment with PARP inhibitors.
Mi-RNA and clinical outcome Marchini et al. [68], who analyzed tumor samples from 144 patients with stage I ovarian cancer, detected that miR-214, miR199a-3p, miR-199a-5p, miR-145, miR-200b and miR-143 were up-regulated whereas miR-30a, miR-30a*, miR-30d, miR-200c and miR-20a were down-regulated in samples from relapsers compared to non-relapsers. On univariate analysis, patients with elevated levels of miR-200c had better progression-free survival (p ¼ 0.0241) and overall survival (p ¼ 0.0230) than those with low levels. Multivariate analysis showed that miR-200c was an independent prognostic factor in a test set for both progressionfree survival (hazard ratio (HR) ¼ 0.035, 95% Confidence Interval (CI) ¼ 0.004-–0.311; p ¼ 0.0026) and overall survival (HR ¼ 0.094, 95% CI ¼ 0.012–0.766, p ¼ 0.0272). Prislei et al. [18], who assessed 220 ovarian cancer patients, suggested that the prognostic relevance of miR-200c expression is dependent on the cellular localization of HuR. When HuR was nuclear, high miR-200c content inhibited TUBB3 expression and resulted in high response to chemotherapy and good prognosis. Conversely, when HuR was cytoplasmic, the role of miR-200c appeared to be just the opposite, i.e. thus yielding to enhanced TUBB3 expression, drugresistance and poor clinical outcome. Therefore, the complex HuR/miR-200c/TUBB3 could represent a potential target for the development of novel therapies for ovarian cancer. By analyzing mi-RNA expression profiling in 55 advanced ovarian carcinomas, Hu et al. [69] found that miR-200a, miR200b and miR-429 were significantly associated with the risk of recurrence and overall survival. In particular, the expression profile of miR-200a from patients who died of disease had a normal distribution, with a peak value centered around 10. In contrast, living patients had a distinct miR-200a profile with a major peak at 11, which represented a two-fold increase in miR200a expression over that in patients who died. The Cox model showed that miR-200a signature was an independent prognostic variable for both recurrence-free survival (p ¼ 0.002) and overall survival (p ¼ 0.0005).
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Low miR-100 levels closely correlated with advanced stage, elevated serum CA125 and short overall survival in a series of 98 patients with ovarian cancer [33]. On multivariate analysis, miR100 expression was an independent predictor of overall survival. Similarly low let-7i levels have been associated with poor clinical outcome in different series [55,70]. Merritt et al. [49] reported that median overall survival was shorter among ovarian cancer patients whose tumors had low levels of Dicer mRNA (2.33 years versus 9.25 years for high levels; p50.001) and Drosha mRNA (2.74 years versus 7.92 years for high levels; p ¼ 0.008). On multivariate analysis, low Dicer expression was an independent predictor of poor survival (HR ¼ 2.10; 95% CI ¼ 1.15–3.85; p ¼ 0.02), whereas a low Drosha mRNA level was not (HR ¼ 1.22; 95% CI ¼ 0.69–2.16; p ¼ 0.50). When paired in an interaction model, low Dicer and low Drosha mRNA levels had a greater association with decreased survival (HR ¼ 4.00; 95% CI ¼ 1.82–9.09; p50.001) than either one alone. Conversely, Zhang et al. [12] found no correlation between the levels of either Drosha or Dicer protein and patient survival. Bentink et al. [71] have recently detected a mi-RNA gene expression signature able to identify an angiogenesis-driven subtype of serous ovarian cancer. This angiogenesis signature has been validated in 10 independent ovarian cancer gene expression datasets and has been significantly associated with survival. This pattern of mi-RNA gene expression could have a strong relevance for the identification of patients who may benefit from the addition of anti-angiogenic agents to standard chemotherapy.
Conclusions mi-RNAs are post-transcriptional regulators of mRNA synthesis which represent a new level of gene expression control. Alterations in the expression of mi-RNAs are involved in the pathogenesis of most human malignancies, including ovarian cancer [5]. In comparison to normal ovary, several mi-RNAs are aberrantly expressed in this cancer. The most significantly over-expressed mi-RNAs are members of the miR-200, whereas miR-100, miR-199a, miR-140, miR-145, miR-125b1 and let-7i were the most down-modulated mi-RNAs [9,11–14,55,70]. Mi-RNAs play a major role in the initiation and progression of ovarian cancer by promoting the expression of proto-oncogenes or by inhibiting the expression of tumor suppressor genes. Several mi-RNAs can modulate the sensitivity of ovarian cancer to platinum and taxane. Some mi-RNAs could be used as biomarkers to identify patients that may benefit from addition of molecularly targeted agents (i.e. anti-angiogenic agents, MET inhibitors and PARP inhibitors) to standard chemotherapy. Moreover, mi-RNAs could represent potential targets for the development of novel therapies for ovarian cancer.
Declaration of interest The authors report no conflicts of interest.
References 1. Garofalo M, Croce CM. MicroRNAs: master regulators as potential therapeutics in cancer. Annu Rev Pharmacol Toxicol 2011;51: 25–43. 2. Mendell JT, Olson EN. MicroRNAs in stress signaling and human disease. Cell 2012;148:1172–87. 3. Kim YK, Kim VN. Processing of intronic microRNAs. EMBO J 2007;26:775–83. 4. Kim VN, Han J, Siomi MC. Biogenesis of small RNAs in animals. Nat Rev Mol Cell Biol 2009;10:126–39. 5. Croce CM. Causes and consequences of microRNA dysregulation in cancer. Nat. Rev. Genet 2009;10:704–14.
Gynecol Endocrinol Downloaded from informahealthcare.com by Ondokuz Mayis Univ. on 05/20/14 For personal use only.
270
A. Gadducci et al.
6. Calin GA, Croce CM. MicroRNA signatures in human cancers. Nat Rev Cancer 2006;6:857–66. 7. Di Leva G, Croce CM. Roles of small RNAs in tumor formation. Trends Mol Med 2010;16:257–67. 8. Garofalo M, Quintavalle C, Romano G, et al. miR221/222 in cancer: their role in tumor progression and response to therapy. Curr Mol Med 2012;12:27–33. 9. Iorio MV, Visone R, Di Leva G, et al. MicroRNA signatures in human ovarian cancer. Cancer Res 2007;67:8699–707. 10. He L, He X, Lim LP, et al. A microRNA component of the p53 tumour suppressor network. Nature 2007;447:1130–4. 11. Nam EJ, Yoon H, Kim SW, et al. MicroRNA expression profiles in serous ovarian carcinoma. Clin Cancer Res 2008;14:2690–5. 12. Zhang L, Volinia S, Bonome T, et al. Genomic and epigenetic alterations deregulate microRNA expression in human epithelial ovarian cancer. Proc Natl Acad Sci USA 2008;105:7004–9. 13. Yang H, Kong W, He L, et al. MicroRNA expression profiling in human ovarian cancer: miR-214 induces cell survival and cisplatin resistance by targeting PTEN. Cancer Res 2008;68:425–33. 14. Dahiya N, Sherman-Baust CA, Wang TL, et al. MicroRNA expression and identification of putative miRNA targets in ovarian cancer. PLoS One 2008;3:e2436. 15. Cao J, Cai J, Huang D, et al. miR-335 represents an invasion suppressor gene in ovarian cancer by targeting Bcl-w. Oncol Rep 2013;30:701–6. 16. Di Leva G, Croce CM. The role of microRNAs in the tumorigenesis of ovarian cancer. Front Oncol 2013;3:153. 17. van Jaarsveld MT, Helleman J, Berns EM, Wiemer EA. MicroRNAs in ovarian cancer biology and therapy resistance. Int J Biochem Cell Biol 2010;42:1282–90. 18. Prislei S, Martinelli E, Mariani M, et al. MiR-200c and HuR in ovarian cancer. BMC Cancer 2013;13:72. 19. Chen Y, Zhang L, Hao Q. Candidate microRNA biomarkers in human epithelial ovarian cancer: systematic review profiling studies and experimental validation. Cancer Cell Int 2013;13:86. 20. Brabletz S, Brabletz T. The ZEB/miR-200 feedback loop – a motor of cellular plasticity in development and cancer? EMBO Rep 2010;11:670–7. 21. Creighton CJ, Gibbons DL, Kurie JM. The role of epithelialmesenchymal transition programming in invasion and metastasis: a clinical perspective. Cancer Manag Res 2013;5:187–95. 22. van Jaarsveld MT, Helleman J, Berns EM, Wiemer EA. MicroRNAs in ovarian cancer biology and therapy resistance. Int J Biochem Cell Biol 2010;42:1282–90. 23. Prislei S, Martinelli E, Mariani M, et al. MiR-200c and HuR in ovarian cancer. BMC Cancer 2013;13:72. 24. Cochrane DR, Spoelstra NS, Howe EN, et al. MicroRNA-200c mitigates invasiveness and restores sensitivity to microtubuletargeting chemotherapeutic agents. Mol Cancer Ther 2009;8: 1055–66. 25. Ferrandina G, Zannoni GF, Martinelli E, et al. Class III beta-tubulin overexpression is a marker of poor clinical outcome in advanced ovarian cancer patients. Clin Cancer Res 2006;12:2774–9. 26. Liu Z, Liu J, Segura MF, et al. MiR-182 overexpression in tumourigenesis of high-grade serous ovarian carcinoma. J Pathol 2012;228:204–15. 27. Poliseno L, Tuccoli A, Mariani L, et al. MicroRNAs modulate the angiogenic properties of HUVECs. Blood 2006;108:3068–71. 28. le Sage C, Nagel R, Egan DA, et al. Regulation of the p27(Kip1) tumor suppressor by miR-221 and miR-222 promotes cancer cell proliferation. Embo J 2007;26:3699–708. 29. Si ML, Zhu S, Wu H, et al. miR-21-mediated tumor growth. Oncogene 2007;26:2799–803. 30. Meng F, Henson R, Wehbe-Janek H, et al. MicroRNA-21 regulates expression of the PTEN tumor suppressor gene in human hepatocellular cancer. Gastroenterology 2007;133:647–58. 31. Frankel LB, Christoffersen NR, Jacobsen A, et al. Programmed cell death 4 (PDCD4) is an important functional target of the microRNA miR-21 in breast cancer cells. J Biol Chem 2007;283:1026–33. 32. Wyman SK, Parkin RK, Mitchell PS, et al. Repertoire of microRNAs in epithelial ovarian cancer as determined by next generation sequencing of small RNA cDNA libraries. PLoS One 2009;4:e5311. 33. Peng DX, Luo M, Qiu LW, et al. Prognostic implications of microRNA-100 and its functional roles in human epithelial ovarian cancer. Oncol Rep 2012;27:1238–44.
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34. Nagaraja AK, Creighton CJ, Yu Z, et al. A link between mir-100 and FRAP1/mTOR in clear cell ovarian cancer. Endocrinol 2010;24: 447–63. 35. Takaki T, Trenz K, Costanzo V, Petronczki M. Polo-like kinase 1 reaches beyond mitosis-cytokinesis, DNA damage response, and development. Curr Opin Cell Biol 2008;20:650–60. 36. Weichert W, Denkert C, Schmidt M, et al. Polo-like kinase isoform expression is a prognostic factor in ovarian carcinoma. Br J Cancer 2004;90:815–21. 37. Zhang W, Wang Q, Yu M, et al. MicroRNA-145 Function as a cell growth repressor by directly targeting c-Myc in human ovarian cancer. Technol Cancer Res Treat 2013. [Epub ahead of print]. 38. Johnson SM, Grosshans H, Shingara J, et al. RAS is regulated by the let-7 microRNA family. Cell 2005;120:635–47. 39. Lee YS, Dutta A. The tumor suppressor microRNA let-7 represses the HMGA2 oncogene. Genes Dev 2007;21:1025–30. 40. Sampson VB, Rong NH, Han J, et al. MicroRNA let-7a downregulates MYC and reverts MYC-induced growth in Burkitt lymphoma cells. Cancer Res 2007;67:9762–70. 41. Johnson CD, Esquela-Kerscher A, Stefani G, et al. The let-7 microRNA represses cell proliferation pathways in human cells. Cancer Res 2007;67:7713–22. 42. Wang Y, Hu X, Greshock J, et al. Genomic DNA copy-number alterations of the let-7 family in human cancers. PLoS One 2012;7: e44399. 43. Yeh YM, Chuang CM, Chao KC, Wang LH. MicroRNA-138 suppresses ovarian cancer cell invasion and metastasis by targeting SOX4 and HIF-1a. Int J Cancer 2013;133:867–78. 44. Felli N, Fontana L, Pelosi E, et al. MicroRNAs 221 and 222 inhibit normal erythropoiesis and erythroleukemic cell growth via kit receptor downmodulation. Proc Natl Acad Sci USA 2005;102: 18081–6. 45. Shedden KA, Kshirsagar MP, Schwartz DR, et al. Histologic type, organ of origin, and Wnt pathway status: effect on gene expression in ovarian and uterine carcinomas. Clin Cancer Res 2005;11: 2123–31. 46. Thrall M, Gallion HH, Kryshio R, et al. BRCA1 expression in a large series of sporadic ovarian carcinomas: a Gynecologic Oncology Group study. Int J Gynecol Cancer 2006;16:166–71. 47. Calura E, Fruscio R, Paracchini L, et al. miRNA landscape in stage i epithelial ovarian cancer defines the histotype specificities. Clin Cancer Res 2013;19:4114–23. 48. Lee H, Park CS, Deftereos G, et al. MicroRNA expression in ovarian carcinoma and its correlation with clinicopathological features. World J Surg Oncol 2012;10:174. 49. Merritt WM, Lin YG, Han LY, et al. Dicer, Drosha, and outcomes in patients with ovarian cancer. N Engl J Med 2008;359:2641–50. 50. Vaksman O, Hetland TE, Trope’ CG, et al. Argonaute, Dicer, and Drosha are up-regulated along tumor progression in serous ovarian carcinoma. Hum Pathol 2012;43:2062–9. 51. Xiang Y, Ma N, Wang D, et al. MiR-152 and miR-185 co-contribute to ovarian cancer cells cisplatin sensitivity by targeting DNMT1 directly: a novel epigenetic therapy independent of decitabine. Oncogene 2013. [Epub ahead of print]. 52. Fu X, Tian J, Zhang L, et al. Involvement of microRNA-93, a new regulator of PTEN/Akt signaling pathway, in regulation of chemotherapeutic drug cisplatin chemosensitivity in ovarian cancer cells. FEBS Lett 2012;586:1279–86. 53. Yang H, Kong W, He L, et al. MicroRNA expression profiling in human ovarian cancer: miR-214 induces cell survival and cisplatin resistance by targeting PTEN. Cancer Res 2008;68:425–33. 54. Kong F, Sun C, Wang Z, et al. miR-125b confers resistance of ovarian cancer cells to cisplatin by targeting pro-apoptotic Bcl-2 antagonist killer 1. J Huazhong Univ Sci Technol Med Sci 2011;31: 543–9. 55. Yang N, Kaur S, Volinia S, et al. MicroRNA microarray identifies Let-7i as a novel biomarker and therapeutic target in human epithelial ovarian cancer. Cancer Res 2008;68:10307–14. 56. Liu N, Zhou C, Zhao J, Chen Y. Reversal of paclitaxel resistance in epithelial ovarian carcinoma cells by a MUC1 aptamer-let-7i chimera. Cancer Invest 2012;30:577–82. 57. Shen L, Cui J, Liang S, et al. Update of research on the role of EZH2 in cancer progression. Oncol Targets Ther 2013;6:321–4. 58. Hu S, Yu L, Li Z, et al. Overexpression of EZH2 contributes to acquired cisplatin resistance in ovarian cancer cells in vitro and in vivo. Cancer Biol Ther 2010;10:788–95.
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DOI: 10.3109/09513590.2013.871525
59. Kuang Y, Cai J, Li D, et al. Repression of Dicer is associated with invasive phenotype and chemoresistance in ovarian cancer. Oncol Lett 2013;5:1149–54. 60. Wang YQ, Guo RD, Guo RM, et al. MicroRNA-182 promotes cell growth, invasion and chemoresistance by targeting programmed cell death 4 (PDCD4) in human ovarian carcinomas. J Cell Biochem 2013;114:1464–73. 61. Huh JH, Kim TH, Kim K, et al. Dysregulation of miR-106a and miR-591 confers paclitaxel resistance to ovarian cancer. Br J Cancer 2013;109:452–61. 62. Cittelly DM, Dimitrova I, Howe EN, et al. Restoration of miR-200c to ovarian cancer reduces tumor burden and increases sensitivity to paclitaxel. Mol Cancer Ther 2012;11: 2556–65. 63. Leskela¨ S, Leandro-Garcı´a LJ, Mendiola M, et al. The miR-200 family controls beta-tubulin III expression and is associated with paclitaxel-based treatment response and progression-free survival in ovarian cancer patients. Endocr Relat Cancer 2010;18: 85–95. 64. Mitamura T, Watari H, Wang L, et al. Downregulation of miRNA-31 induces taxane resistance in ovarian cancer cells through increase of receptor tyrosine kinase MET. Oncogenesis 2013;2:e40.
Micro-RNAs and ovarian cancer
271
65. Bu R, Uddin S, Bavi P, et al. HGF/c-Met pathway has a prominent role in mediating antiapoptotic signals through AKT in epithelial ovarian carcinoma. Lab Invest 2011;91:124–37. 66. Zillhardt M, Park SM, Romero IL, et al. Foretinib (GSK1363089), an orally available multikinase inhibitor of c-Met and VEGFR-2, blocks proliferation, induces anoikis, and impairs ovarian cancer metastasis. Clin Cancer Res 2011;17:4042–51. 67. Neijenhuis S, Bajrami I, Miller R, et al. Identification of miRNA modulators to PARP inhibitor response. DNA Repair 2013;12: 394–402. 68. Marchini S, Cavalieri D, Fruscio R, et al. Association between miR200c and the survival of patients with stage I epithelial ovarian cancer: a retrospective study of two independent tumour tissue collections. Lancet Oncol 2011;12:273–85. 69. Hu X, Macdonald DM, Huettner PC, et al. A miR-200 microRNA cluster as prognostic marker in advanced ovarian cancer. Gynecol Oncol 2009;114:457–64. 70. Nam EJ, Yoon H, Kim SW, et al. MicroRNA expression profiles in serous ovarian carcinoma. Clin Cancer Res 2008;14: 2690–5. 71. Bentink S, Haibe-Kains B, Risch T, et al. Angiogenic mRNA and microRNA gene expression signature predicts a novel subtype of serous ovarian cancer. PLoS One 2012;7:e30269.
OVARIAN CANCER
Micro-RNAs and ovarian cancer: the state of art and perspectives of clinical research Angiolo Gadducci, Claudia Sergiampietri, Nora Lanfredini, and Ilaria Guiggi
Abstract
Keywords
Dysregulation of microRNA (mi-RNA) expression plays a major role in the development and progression of most human malignancies. Members of the miR-200 family, miR-182, miR-214 and miR-221 are frequently up-regulated, whereas miR-100, let-7i, miR-199a, miR-125b, mir-145 and miR-335 are often down-regulated in ovarian cancer compared with normal ovarian tissue. Most mi-RNA signatures are overlapping in different tumor histotypes but some mi-RNAs seem to be histotype specific. For instance, the endometrioid type shares with the serous and clear cell types the up-regulation of miR-200 family members, but also presents over-expression of miR-21, miR-202 and miR-205. Clear cell carcinoma has a significantly higher expression of miR30a and miR-30a*, whereas mucinous histotype has elevated levels of miR-192/194. In vitro and in vivo investigations have shown that several mi-RNAs can modulate the sensitivity of ovarian cancer to platinum and taxane, and clinical studies have suggested that mi-RNA profiling may predict the outcome of patients with this malignancy. Some mi-RNAs could be used as biomarkers to identify patients that might benefit from the addition of molecularly targeted agents (i.e. anti-angiogenic agents, MET inhibitors and poly(ADP-ribose) polymerase (PARP) inhibitors) to standard chemotherapy. Moreover, mi-RNAs could represent potential targets for the development of novel therapies.
Biomarkers, chemoresistance, micro-RNAs, ovarian cancer, prognosis
Introduction MicroRNAs (mi-RNAs) are small non-coding single-stranded RNAs that negatively regulate gene expression and are involved in the regulation of key cellular processes such as cell cycle, differentiation and apoptosis [1,2]. Human genoma encodes approximately 1000 mi-RNAs able to regulate up to 60% of all transcriptome [3]. Mi-RNA primary transcripts are first released and then processed by the RNase III-type endonucleases Drosha and Dicer to produce mature mi-RNAs of 21–22 nucleotides [4]. Fully-processed mi-RNAs associate with the Argonaute proteins within the effector complex termedas a RNA-induced silencing complex (RISC). RISC binds to the 30 -untranslated region (UTR) of the target mRNA in a sequence-specific manner, and down-regulates gene expression through either inhibition of translation or increased degradation of RNA. Mi-RNA activity is characterized by redundancy, since each mi-RNA regulates hundreds or thousands of targets and different mi-RNAs may also repress the same target ([2]. Dysregulation of mi-RNA expression plays a major essential role in tumorigenesis [5–7]. It is noteworthy that same mi-RNAs can act as an oncogene in one cell type and as a tumor suppressor in another one because of different targets and mechanisms of action [5]. For instance, miR222/221 cluster is over-expressed in breast, lung or liver cancers where targets are tumor suppressor genes such as PTEN, p27 and
Address for correspondence: Angiolo Gadducci, Clinical and Experimental Medicine, Division of Gynecology and Obstetrics, University of Pisa, Via Roma 56, Pisa, 56127, Italy. Tel: 39 50 992609. Fax: 39 50 553410. E-mail: [email protected]
History Received 24 October 2013 Revised 29 October 2013 Accepted 29 November 2013 Published online 30 January 2014
p57, while the same cluster is down-regulated in erythroblastic leukemia where target is c-KIT oncogene [8].The application of the high-throughput technologies has allowed the identification of cancer-specific mi-RNA fingerprints in all human cancers, and the patterns of mi-RNA expression may provide useful information for tumor classification and prognosis [5,6]. The present paper has reviewed the literature data about the relevance of mi-RNAs for the pathogenesis, the response to chemotherapy and the prognosis of ovarian cancer.
Altered mi-RNA expression and ovarian carcinogenesis
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Department of Clinical and Experimental Medicine, Division of Gynecology and Obstetrics, University of Pisa, Pisa, Italy
Members of the miR-200 family (miR-200a, miR-200b, miR200c, miR-141), miR-182, miR-214 and miR-221 are frequently up-regulated, whereas miR-100, let-7i, miR-199a, miR-125b, mir145 and miR-335 are often down-regulated in ovarian cancer compared with normal ovarian tissue [9–18] (Table 1). miR-200a and miR-200b are located on chromosome 1, while miR-200c and miR-141 are placed on chromosome 12 [19]. miR200a, miR-200b, miR-200c and miR-141 have BRCA1-associated protein [BAP-1] as common target, that is down-modulated in ovarian cancer [9]. Other prominent targets of the miR-200 family are two E-box binding transcription factors, termed ZEB1 and ZEB2, involved in a complex network of transcriptional repressors regulating E-cadherin expression and epithelial polarity [19,20]. Moreover, miR-200 family is a powerful regulator of the epithelial-to-mesenchymal transition [EMT], a reversible embryonic program aberrantly activated in tumor progression [21]. Another target of this family is class III b-tubulin (TUBB3), which is over-expressed in several malignancies such as ovarian cancer [22–25].
Micro-RNAs and ovarian cancer
DOI: 10.3109/09513590.2013.871525
Table 1. Micro-RNA altered in ovarian cancer. Micro-RNA Upregulated miR-200 famiy (miR-200a, miR-200b, miR-200c, miR-141) miR-182 miR-214 miR-221 Downregulated miR-100 let-7 family
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miR-199a miR-125b miR-145 MiR-335
Potential targets BAP-1, ZEB1, ZEB2, TUBB3 BRCA1, MTSS1, HMGA2 PTEN c-kit, p27kip1 AKT/m-TOR, Plk-1 KRAS, HMGA2, c-Myc, CDC25A, CDK6, CDK4, cyclin A, cyclin D, cyvlin D2, cyclin D3 HIF-1a, VEGF HIF-1a, VEGF c-myc Blc-w
Yang et al. [13] found that 36 out of 515 mi-RNAs showed differential expression between normal ovarian surface epithelial cells and ovarian cancer. In particular, elevated levels of miR-214 and miR-200a were found in 56% and 43%, respectively, of ovarian carcinomas and were especially associated with highgrade and advanced disease, whereas 76% of these tumors showed down-regulated miR-100. miR-214 enhances cell survival through targeting the 30 -UTR of the PTEN, which leads to PTEN downregulation and activation of Akt-mTOR pathway. Inhibition of Akt with a specific inhibitor or the introduction of PTEN cDNA lacking 3’-UTR abrogates miR-214-induced cell survival. Using mi-RNA profiling analysis, Liu et al. [26] found that miR-182 expression was significantly higher in serous tubal intraepithelial carcinoma, a precursor of high-grade serous ovarian cancer, than in matched normal Fallopian tube, and that miR-182 was significantly over-expressed in most high-grade serous ovarian carcinomas. The oncogenic properties of miR-182 are mediated in part by its impaired repair of DNA double-strand breaks and negative regulation of BRCA1 and metastasis suppressor 1 (MTSS1) expression as well as its positive regulation of the oncogene high-mobility group AT-hook 2 [HMGA2]. Dahiya et al. [14] determined mi-RNA expression profiles in 34 ovarian cancer tissues, in 10 ovarian cancer cell lines, and in an immortalized human ovarian surface epithelium cell line as control. miR-221 was the most highly elevated mi-RNA in both tissues and cancer cell lines (9-fold and 7-fold, respectively), while miR-21 was significantly decreased in both sample types (3-fold and 9-fold, respectively). miR-221 targets c-KIT [27] and p27kip1 [28], whereas miR-21 could modulate tumorigenesis through regulation of BCL2 [29], PTEN [30] and programed cell death 4 [PDCD4] [31]. miR-100 has been reported to be down-regulated in five profiling studies and up-regulated in only one [9,11–14,32]. The transfection of SKOV-3 ovarian cancer cells with pre-miR-100 and anti-miR-100 showed that cell viability could be inhibited by upregulation of miR-100, and could be promoted by down-regulation of this mi-RNA [33]. Over-expression of miR-100 inhibited AKT/ m-TOR signaling pathway and enhanced sensitivity of human ovarian clear cell lines to the rapamycin analog everolimus [34]. MiR-100 may also function as a tumor suppressor by targeting Polo-like kinase 1 (Plk1), a serine/threonine kinase that is involved in the mitosis regulation [35] and that is over-expressed in different malignancies including ovarian cancer [36]. miR-145 has been found to inhibit proliferation and to promote apoptosis in OVCAR-3 and SKOV-3 ovarian cancer cell lines by targeting c-Myc [37].
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The let-7 family, one of the first mi-RNA families shown to be involved in human cancer, inhibits many oncogenic proteins, such as KRAS [38], HMGA2 [39] and c-Myc [40]. In addition, let-7i targets multiple cell cycle-associated genes, including CDC25A, CDK6, CDK4, cyclin A, cyclin D1, cyclin D2 and cyclin D3 [41]. Wang et al. [42] observed that cell proliferation of the ovarian cancer cell lines A2780 and 2008 was significantly reduced after 72 h from the transfection with a let-7 b mimic. miR-199a and miR-125b were found to be down-regulated in ovarian cancer tissues and in the cell lines A2780 and OVCAR-3 [10]. The ectopic expression of miR-199a or miR-125b inhibited tumor angiogenesis both in vitro and in vivo. Over-expression of miR-199a/125b dramatically down-regulated hypoxia-inducible factor-1a (HIF-1a) protein and vascular endothelial growth factor (VEGF) mRNA levels, suggesting that these mi-RNAs exerted an anti-angiogenic effect by decreasing the expression of HIF-1a and VEGF. Cao et al. [15] reported that miR-335 was down-regulated in four ovarian cancer cell lines compared with normal ovarian epithelium tissues. In vitro over-expression of miR-335 suppressed cell migration and invasion, but exhibited a negligible effect on cell proliferation. B-cell CLL/lymphoma 2 like 2 (Bclw), a pro-survival member of the Bcl-2 family, was identified as a potential target of miR-335. The expression of Bcl-w and its effector matrix metalloproteinase (MMP)-2 was down-regulated after transfection with miR-335 mimics, whereas ectopic Bcl-w abrogated the effect of miR-335 over-expression on ovarian cancer cell migration and invasion. In an orthotopic xenograft mouse model, the expression of miR-138 inhibited ovarian cancer spread to other organs [43]. miR-138 directly targeted SRY-related high mobility group box 4 (SOX4) and HIF-1a, and over-expression of SOX4 and HIF-1a reversed the miR-138-mediated suppression of cell invasion. These data supported a novel potential therapeutic strategy for ovarian cancer. Experimental studies on serous ovarian cancer showed that miR-506 increased E-cadherin expression, inhibited cell migration and invasion, and prevented TGFb-induced EMT by targeting SNAI2, a transcriptional repressor of E-cadherin. Nanoparticle delivery of miR-506 in orthotopic ovarian cancer mouse models resulted in E-cadherin accumulation and tumor growth suppression.
Mi-RNA and ovarian cancer: relationship with pathological features Iorio et al. [9], who assessed the genome-wide mi-RNA expression profiling in 84 frozen normal and malignant ovarian tissues, found that most mi-RNA signatures were overlapping in different tumor histotypes but that a number of mi-RNAs seemed to be histotype specific. For instance, the endometrioid type shared with the serous and clear cell types the up-regulation of miR-200a, miR-200b, miR-200c and miR-141, but also presented over-expression of miR-21, miR-202 and miR-205. miR-125b1, miR199a and miR-140 were down-modulated in serous, clear cell and endometrioid carcinomas, miR-145 was down-regulated in both serous and clear cell carcinomas, miR-222 was downmodulated in both endometrioid and clear cell carcinomas, and miR-212 was down-regulated in serous carcinoma. miR-145 is predicted to target c-SRK, MMP-13, and fibroblast growth factor2 (FGF2) [9], miR-222 targets c-Kit [44], and miR-212 targets WT1 [45] and BRCA1 [46] that is often involved also in the pathogenesis of sporadic high-grade serous ovarian cancer. An Italian investigation on 257 frozen specimens from stage I ovarian cancer detected that clear cell carcinoma had a five-fold higher expression of miR-30a and miR-30a*, whereas mucinous histotype had five-fold higher levels of miR-192/194 [47].
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The analysis of 171 formalin-fixed, paraffin-embedded ovarian tissue samples revealed a different expression of miR-30c, miR30d, miR-30e-3p and miR-370 between carcinomas and benign ovarian tissues as well as between carcinomas and borderline tumors [48]. Moreover, miR-181d, miR-30a-3p, miR-532-5p were significantly different between carcinoma and borderline tissues. Among ovarian carcinomas, the expression of miR-30a-3p, miR30c, miR-30d, miR-30e-3p was lowest in mucinous and highest in clear cell histotype, the expression of miR-30a-3p was higher in well-differentiated compared with poorly differentiated tumors, and the expression of miR-370 was higher in early compared with advanced stages. Zhang et al. [12], who assessed 106 human ovarian cancer specimens, found that the expression of several mi-RNAs was significantly different between early and advanced disease, and that mi-RNA alterations mainly consisted in down-regulation in advanced stages. According to histological grade, 13 mi-RNAs exhibited significant differences and all were down-regulated in high-grade compared with the low-grade disease. On the other hand, no significant difference in mRNA levels and immunohistochemical expression of Drosha and Dicer was found between early and advanced disease. Conversely Merritt et al. [49], who analyzed 111 ovarian cancer specimens, observed that low Dicer expression was associated with advanced stage (¼0.007), whereas low Drosha expression was related with suboptimal surgical cytoreduction (p ¼ 0.02). Vaksman et al. [50] assessed Drosha, Dicer, Argonaute 1 and Argonaute 2 mRNA in 144 ovarian cancer specimens (82 effusions, 33 primary tumors and 29 metastases). Significantly elevated levels of all four mRNAs were detected in effusions compared with primary carcinomas (p50.001 to p ¼ 0.006), whereas Argonaute 2 mRNA (p ¼ 0.002) and Drosha mRNA (p ¼ 0.009) were over-expressed in metastases compared with primary tumors. Higher mRNA levels of Dicer (p ¼ 0.003), Drosha (p ¼ 0.01) and Argonaute 1 (p ¼ 0.01) were associated with high-grade histology in primary carcinomas. Elevated Argonaute-2 m-RNA levels in prechemotherapy effusions were an independent prognostic variable for poor progression-free survival (p ¼ 0.046). The different expression of Drosha, Dicer, Argonaute 1,and Argonaute 2 in metastatic sites compared with primary tumors could suggest an involvement of these molecules in ovarian cancer progression.
Mi-RNA and sensitivity to chemotherapy Several in vitro and in vivo investigations have shown that expression of some mi-RNAs can modulate the sensitivity of ovarian cancer to chemotherapeutic agents (Table 2). miR-152 and miR-185 have been found to be significantly down-regulated in the cisplatin-resistant ovarian cancer cell lines SKOV-3/DDP and A2780/DDP compared with their sensitive parent lines SKOV-3 and A2780, respectively [51]. The over-expression of miR-152 or miR-185 increased cisplatin sensitivity by DNA methyltransferase-1 (DNMT-1) suppression. Nude mice intraperitoneally injected with SKOV-3/DDP cells transfected with miR152 mimics showed a better response to cisplatin. The over-expression of miR-93, targeting PTEN, increased the ratio of phosphorylated Akt/total Akt and enhanced the development of cisplatin resistance in the cell lines OVCAR-3 and SKOV-3 [52]. Similarly, miR-214 appeared to induce cisplatin resistance primarily through targeting the PTEN/Akt/m-Tor pathway [53]. Infact, the inhibition of Akt with a small molecule named Akt/protein kinase B signaling inhibitor-2 (API-2) or the introduction of PTEN cDNA lacking 3’-UTR largely abrogated miR-214-induced cell survival. Over-expression of miR-125b caused a marked inhibition of cisplatin-induced cytotoxicity and
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Table 2. Micro-RNA and sensitivity to chemotherapy. Micro-RNA
Target
#miR-152 #miR-185 "miR-93 "miR-214 "miR-125b #let-7i "miR-182
DNMT-1 DNMT-1 PTEN PTEN/AKT/m-Tor BAK-1 RAS, HMGA2, c-myc, CDC25A, CDK6, Cyckin D2 PDCD4
"miR-106a #miR-591 #miR-200c #miR-31 "has-miR 107 "has-miR 222
BLC10, caspase 7 ZEB1 TUBB3 HGF/c-MET RAD51 RAD51
Chemotherapy Cisplatin Cisplatin Cisplatin Cisplatin Cisplatin Cisplatin
resistance resistance resistance resistance resistance resistance
Cisplatin and paclitaxel resistance Paclitaxel resistance Paclitaxel resistance Paclitaxel resistance Paclitaxel resistance PARP inhibitor sensitivity PARP inhibitor sensitivity
apoptosis in OV2008 and C13* cells through down-regulation of the pro-apoptotic Bcl-2 antagonist killer 1 (BAK-1) [54]. The analysis of frozen specimens from 69 advanced ovarian cancer patients revealed that let-7i was expressed at significantly lower levels in the non-complete responders than in complete responders to first-line platinum-based chemotherapy (p ¼ 0.003) [55]. Both loss-of-function (by synthetic let-7i inhibitor) and gainof-function (by retroviral over-expression of let-7i) studies confirmed that reduced let-7i expression significantly increased the resistance to cisplatin. A chimera that combined MUC1 aptamer and let-7i was delivered into OVCAR-3 cells and the released let-7i significantly sensitized tumor cells to paclitaxel, which consequents cell proliferation arrest, apoptosis induction, and decreased survival [56]. The growing advances in oligonucleotide/nanoparticle technologies could allow to use let-7i as a new therapeutic target for ovarian cancer treatment [55]. Enhancer of zeste homologue 2 (EZH2), that encodes a histone methyltransferase, is involved in cancer development and progression through epigenetic gene silencing and chromatin remodeling [57]. EZH2 was found to be over-expressed in cisplatin-resistant ovarian cancer cells, and knockdown of EZH2 by RNA interference resensitized resistant cells to this chemotherapeutic agent [58]. Moreover, loss of EZH2 enhanced sensibility of tumor xenografts to cisplatin and inhibited tumor growth in vivo. Kuang et al. [59] demonstrated that the expression of Dicer was significantly decreased in cisplatin-resistant A2780/ DDP cells and that EZH2 depletion by short hairpin RNA increased the expression of Dicer in vitro, thus suggesting a critical role for EZH2 in the regulation of this endonuclease. Wang et al. [60] found that miR-182 was up-regulated and PDCD4 was down-regulated in ovarian cancer tissues and cell lines and that the increase or blocking of miR-182 led to an opposite alteration of PDCD4. In vitro studies of miR-182 blockage suppressed whereas miR-182 mimics enhanced viability and colony formation of ovarian cancer cells. Moreover, miR-182 reduced cell sensitivity to cisplatin and paclitaxel, probably through its anti-apoptosis activity. Up-regulation of miR-106a and down-regulation of miR-591 were detected to be associated with paclitaxel resistance in ovarian cancer cells and tumor samples [61]. Transfection with anti-miR-106a or pre-miR-591 resensitized resistant cells to paclitaxel. ZEB1 is a target gene of miR591, whereas BCL10 and caspase-7 are target genes of miR-106a. The expression of miR-200c, a regulator of TUBB3, correlated with chemoresistance in a panel of ovarian cancer cell lines [62]. In a xenograft model, miR-200c reduced tumor burden and increased sensitivity to paclitaxel. Low tumor miR-200 expression
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DOI: 10.3109/09513590.2013.871525
was significantly associated with high TUBB3 protein content in a series of 72 ovarian carcinomas [63]. It is noteworthy that noncomplete responders had lower miR-200c levels than complete responders to paclitaxel-based chemotherapy (p ¼ 0.037). Mitamura et al. [64] reported that miR-31 was down-regulated in the paclitaxel-resistant KFr13Tx ovarian cancer cells, and that re-introduction of miR-31 re-sensitized them to paclitaxel both in vitro and in vivo. miR-31 binds to the 3’-UTR of mRNA of the hepatocyte growth factor (HGF) receptor tyrosine kinase MET. HGF/c-MET pathway has a prominent role in mediating antiapoptotic signals through the activation of a phosphatydi-inosotolkinase (PIK)-3/AKT-dependent mechanism [65]. Co-treatment of paclitaxel-resistant cells with MET inhibitors sensitized tumor cells to paclitaxel [64]. Multikinase inhibitors suppressing MET and VEGFR activity have been reported to inhibit proliferation and metastasis of ovarian cancer [66]. Clinical investigations are strongly warranted to assess whether poor responders to chemotherapy might be rescued by a combination of standard chemotherapy with MET inhibitors. Poly(ADP-ribose) polymerase (PARP) inhibitors are effective in killing cells deficient in HR, such as those bearing BRCA1-2 mutations. Neijenhuis et al. [67] found that hsa-miR-107 and hsamiR-222 sensitize tumor cells to the PARP inhibitor olaparib, by repressing the expression of RAD51 and impairing the double strand break repair by HR. Elevated expression of hsa-miR-107 has been detected in a subset of ovarian clear cell carcinomas. These mi-RNAs could be used as biomarkers to identify patients that may benefit from treatment with PARP inhibitors.
Mi-RNA and clinical outcome Marchini et al. [68], who analyzed tumor samples from 144 patients with stage I ovarian cancer, detected that miR-214, miR199a-3p, miR-199a-5p, miR-145, miR-200b and miR-143 were up-regulated whereas miR-30a, miR-30a*, miR-30d, miR-200c and miR-20a were down-regulated in samples from relapsers compared to non-relapsers. On univariate analysis, patients with elevated levels of miR-200c had better progression-free survival (p ¼ 0.0241) and overall survival (p ¼ 0.0230) than those with low levels. Multivariate analysis showed that miR-200c was an independent prognostic factor in a test set for both progressionfree survival (hazard ratio (HR) ¼ 0.035, 95% Confidence Interval (CI) ¼ 0.004-–0.311; p ¼ 0.0026) and overall survival (HR ¼ 0.094, 95% CI ¼ 0.012–0.766, p ¼ 0.0272). Prislei et al. [18], who assessed 220 ovarian cancer patients, suggested that the prognostic relevance of miR-200c expression is dependent on the cellular localization of HuR. When HuR was nuclear, high miR-200c content inhibited TUBB3 expression and resulted in high response to chemotherapy and good prognosis. Conversely, when HuR was cytoplasmic, the role of miR-200c appeared to be just the opposite, i.e. thus yielding to enhanced TUBB3 expression, drugresistance and poor clinical outcome. Therefore, the complex HuR/miR-200c/TUBB3 could represent a potential target for the development of novel therapies for ovarian cancer. By analyzing mi-RNA expression profiling in 55 advanced ovarian carcinomas, Hu et al. [69] found that miR-200a, miR200b and miR-429 were significantly associated with the risk of recurrence and overall survival. In particular, the expression profile of miR-200a from patients who died of disease had a normal distribution, with a peak value centered around 10. In contrast, living patients had a distinct miR-200a profile with a major peak at 11, which represented a two-fold increase in miR200a expression over that in patients who died. The Cox model showed that miR-200a signature was an independent prognostic variable for both recurrence-free survival (p ¼ 0.002) and overall survival (p ¼ 0.0005).
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Low miR-100 levels closely correlated with advanced stage, elevated serum CA125 and short overall survival in a series of 98 patients with ovarian cancer [33]. On multivariate analysis, miR100 expression was an independent predictor of overall survival. Similarly low let-7i levels have been associated with poor clinical outcome in different series [55,70]. Merritt et al. [49] reported that median overall survival was shorter among ovarian cancer patients whose tumors had low levels of Dicer mRNA (2.33 years versus 9.25 years for high levels; p50.001) and Drosha mRNA (2.74 years versus 7.92 years for high levels; p ¼ 0.008). On multivariate analysis, low Dicer expression was an independent predictor of poor survival (HR ¼ 2.10; 95% CI ¼ 1.15–3.85; p ¼ 0.02), whereas a low Drosha mRNA level was not (HR ¼ 1.22; 95% CI ¼ 0.69–2.16; p ¼ 0.50). When paired in an interaction model, low Dicer and low Drosha mRNA levels had a greater association with decreased survival (HR ¼ 4.00; 95% CI ¼ 1.82–9.09; p50.001) than either one alone. Conversely, Zhang et al. [12] found no correlation between the levels of either Drosha or Dicer protein and patient survival. Bentink et al. [71] have recently detected a mi-RNA gene expression signature able to identify an angiogenesis-driven subtype of serous ovarian cancer. This angiogenesis signature has been validated in 10 independent ovarian cancer gene expression datasets and has been significantly associated with survival. This pattern of mi-RNA gene expression could have a strong relevance for the identification of patients who may benefit from the addition of anti-angiogenic agents to standard chemotherapy.
Conclusions mi-RNAs are post-transcriptional regulators of mRNA synthesis which represent a new level of gene expression control. Alterations in the expression of mi-RNAs are involved in the pathogenesis of most human malignancies, including ovarian cancer [5]. In comparison to normal ovary, several mi-RNAs are aberrantly expressed in this cancer. The most significantly over-expressed mi-RNAs are members of the miR-200, whereas miR-100, miR-199a, miR-140, miR-145, miR-125b1 and let-7i were the most down-modulated mi-RNAs [9,11–14,55,70]. Mi-RNAs play a major role in the initiation and progression of ovarian cancer by promoting the expression of proto-oncogenes or by inhibiting the expression of tumor suppressor genes. Several mi-RNAs can modulate the sensitivity of ovarian cancer to platinum and taxane. Some mi-RNAs could be used as biomarkers to identify patients that may benefit from addition of molecularly targeted agents (i.e. anti-angiogenic agents, MET inhibitors and PARP inhibitors) to standard chemotherapy. Moreover, mi-RNAs could represent potential targets for the development of novel therapies for ovarian cancer.
Declaration of interest The authors report no conflicts of interest.
References 1. Garofalo M, Croce CM. MicroRNAs: master regulators as potential therapeutics in cancer. Annu Rev Pharmacol Toxicol 2011;51: 25–43. 2. Mendell JT, Olson EN. MicroRNAs in stress signaling and human disease. Cell 2012;148:1172–87. 3. Kim YK, Kim VN. Processing of intronic microRNAs. EMBO J 2007;26:775–83. 4. Kim VN, Han J, Siomi MC. Biogenesis of small RNAs in animals. Nat Rev Mol Cell Biol 2009;10:126–39. 5. Croce CM. Causes and consequences of microRNA dysregulation in cancer. Nat. Rev. Genet 2009;10:704–14.
Gynecol Endocrinol Downloaded from informahealthcare.com by Ondokuz Mayis Univ. on 05/20/14 For personal use only.
270
A. Gadducci et al.
6. Calin GA, Croce CM. MicroRNA signatures in human cancers. Nat Rev Cancer 2006;6:857–66. 7. Di Leva G, Croce CM. Roles of small RNAs in tumor formation. Trends Mol Med 2010;16:257–67. 8. Garofalo M, Quintavalle C, Romano G, et al. miR221/222 in cancer: their role in tumor progression and response to therapy. Curr Mol Med 2012;12:27–33. 9. Iorio MV, Visone R, Di Leva G, et al. MicroRNA signatures in human ovarian cancer. Cancer Res 2007;67:8699–707. 10. He L, He X, Lim LP, et al. A microRNA component of the p53 tumour suppressor network. Nature 2007;447:1130–4. 11. Nam EJ, Yoon H, Kim SW, et al. MicroRNA expression profiles in serous ovarian carcinoma. Clin Cancer Res 2008;14:2690–5. 12. Zhang L, Volinia S, Bonome T, et al. Genomic and epigenetic alterations deregulate microRNA expression in human epithelial ovarian cancer. Proc Natl Acad Sci USA 2008;105:7004–9. 13. Yang H, Kong W, He L, et al. MicroRNA expression profiling in human ovarian cancer: miR-214 induces cell survival and cisplatin resistance by targeting PTEN. Cancer Res 2008;68:425–33. 14. Dahiya N, Sherman-Baust CA, Wang TL, et al. MicroRNA expression and identification of putative miRNA targets in ovarian cancer. PLoS One 2008;3:e2436. 15. Cao J, Cai J, Huang D, et al. miR-335 represents an invasion suppressor gene in ovarian cancer by targeting Bcl-w. Oncol Rep 2013;30:701–6. 16. Di Leva G, Croce CM. The role of microRNAs in the tumorigenesis of ovarian cancer. Front Oncol 2013;3:153. 17. van Jaarsveld MT, Helleman J, Berns EM, Wiemer EA. MicroRNAs in ovarian cancer biology and therapy resistance. Int J Biochem Cell Biol 2010;42:1282–90. 18. Prislei S, Martinelli E, Mariani M, et al. MiR-200c and HuR in ovarian cancer. BMC Cancer 2013;13:72. 19. Chen Y, Zhang L, Hao Q. Candidate microRNA biomarkers in human epithelial ovarian cancer: systematic review profiling studies and experimental validation. Cancer Cell Int 2013;13:86. 20. Brabletz S, Brabletz T. The ZEB/miR-200 feedback loop – a motor of cellular plasticity in development and cancer? EMBO Rep 2010;11:670–7. 21. Creighton CJ, Gibbons DL, Kurie JM. The role of epithelialmesenchymal transition programming in invasion and metastasis: a clinical perspective. Cancer Manag Res 2013;5:187–95. 22. van Jaarsveld MT, Helleman J, Berns EM, Wiemer EA. MicroRNAs in ovarian cancer biology and therapy resistance. Int J Biochem Cell Biol 2010;42:1282–90. 23. Prislei S, Martinelli E, Mariani M, et al. MiR-200c and HuR in ovarian cancer. BMC Cancer 2013;13:72. 24. Cochrane DR, Spoelstra NS, Howe EN, et al. MicroRNA-200c mitigates invasiveness and restores sensitivity to microtubuletargeting chemotherapeutic agents. Mol Cancer Ther 2009;8: 1055–66. 25. Ferrandina G, Zannoni GF, Martinelli E, et al. Class III beta-tubulin overexpression is a marker of poor clinical outcome in advanced ovarian cancer patients. Clin Cancer Res 2006;12:2774–9. 26. Liu Z, Liu J, Segura MF, et al. MiR-182 overexpression in tumourigenesis of high-grade serous ovarian carcinoma. J Pathol 2012;228:204–15. 27. Poliseno L, Tuccoli A, Mariani L, et al. MicroRNAs modulate the angiogenic properties of HUVECs. Blood 2006;108:3068–71. 28. le Sage C, Nagel R, Egan DA, et al. Regulation of the p27(Kip1) tumor suppressor by miR-221 and miR-222 promotes cancer cell proliferation. Embo J 2007;26:3699–708. 29. Si ML, Zhu S, Wu H, et al. miR-21-mediated tumor growth. Oncogene 2007;26:2799–803. 30. Meng F, Henson R, Wehbe-Janek H, et al. MicroRNA-21 regulates expression of the PTEN tumor suppressor gene in human hepatocellular cancer. Gastroenterology 2007;133:647–58. 31. Frankel LB, Christoffersen NR, Jacobsen A, et al. Programmed cell death 4 (PDCD4) is an important functional target of the microRNA miR-21 in breast cancer cells. J Biol Chem 2007;283:1026–33. 32. Wyman SK, Parkin RK, Mitchell PS, et al. Repertoire of microRNAs in epithelial ovarian cancer as determined by next generation sequencing of small RNA cDNA libraries. PLoS One 2009;4:e5311. 33. Peng DX, Luo M, Qiu LW, et al. Prognostic implications of microRNA-100 and its functional roles in human epithelial ovarian cancer. Oncol Rep 2012;27:1238–44.
Gynecol Endocrinol, 2014; 30(4): 266–271
34. Nagaraja AK, Creighton CJ, Yu Z, et al. A link between mir-100 and FRAP1/mTOR in clear cell ovarian cancer. Endocrinol 2010;24: 447–63. 35. Takaki T, Trenz K, Costanzo V, Petronczki M. Polo-like kinase 1 reaches beyond mitosis-cytokinesis, DNA damage response, and development. Curr Opin Cell Biol 2008;20:650–60. 36. Weichert W, Denkert C, Schmidt M, et al. Polo-like kinase isoform expression is a prognostic factor in ovarian carcinoma. Br J Cancer 2004;90:815–21. 37. Zhang W, Wang Q, Yu M, et al. MicroRNA-145 Function as a cell growth repressor by directly targeting c-Myc in human ovarian cancer. Technol Cancer Res Treat 2013. [Epub ahead of print]. 38. Johnson SM, Grosshans H, Shingara J, et al. RAS is regulated by the let-7 microRNA family. Cell 2005;120:635–47. 39. Lee YS, Dutta A. The tumor suppressor microRNA let-7 represses the HMGA2 oncogene. Genes Dev 2007;21:1025–30. 40. Sampson VB, Rong NH, Han J, et al. MicroRNA let-7a downregulates MYC and reverts MYC-induced growth in Burkitt lymphoma cells. Cancer Res 2007;67:9762–70. 41. Johnson CD, Esquela-Kerscher A, Stefani G, et al. The let-7 microRNA represses cell proliferation pathways in human cells. Cancer Res 2007;67:7713–22. 42. Wang Y, Hu X, Greshock J, et al. Genomic DNA copy-number alterations of the let-7 family in human cancers. PLoS One 2012;7: e44399. 43. Yeh YM, Chuang CM, Chao KC, Wang LH. MicroRNA-138 suppresses ovarian cancer cell invasion and metastasis by targeting SOX4 and HIF-1a. Int J Cancer 2013;133:867–78. 44. Felli N, Fontana L, Pelosi E, et al. MicroRNAs 221 and 222 inhibit normal erythropoiesis and erythroleukemic cell growth via kit receptor downmodulation. Proc Natl Acad Sci USA 2005;102: 18081–6. 45. Shedden KA, Kshirsagar MP, Schwartz DR, et al. Histologic type, organ of origin, and Wnt pathway status: effect on gene expression in ovarian and uterine carcinomas. Clin Cancer Res 2005;11: 2123–31. 46. Thrall M, Gallion HH, Kryshio R, et al. BRCA1 expression in a large series of sporadic ovarian carcinomas: a Gynecologic Oncology Group study. Int J Gynecol Cancer 2006;16:166–71. 47. Calura E, Fruscio R, Paracchini L, et al. miRNA landscape in stage i epithelial ovarian cancer defines the histotype specificities. Clin Cancer Res 2013;19:4114–23. 48. Lee H, Park CS, Deftereos G, et al. MicroRNA expression in ovarian carcinoma and its correlation with clinicopathological features. World J Surg Oncol 2012;10:174. 49. Merritt WM, Lin YG, Han LY, et al. Dicer, Drosha, and outcomes in patients with ovarian cancer. N Engl J Med 2008;359:2641–50. 50. Vaksman O, Hetland TE, Trope’ CG, et al. Argonaute, Dicer, and Drosha are up-regulated along tumor progression in serous ovarian carcinoma. Hum Pathol 2012;43:2062–9. 51. Xiang Y, Ma N, Wang D, et al. MiR-152 and miR-185 co-contribute to ovarian cancer cells cisplatin sensitivity by targeting DNMT1 directly: a novel epigenetic therapy independent of decitabine. Oncogene 2013. [Epub ahead of print]. 52. Fu X, Tian J, Zhang L, et al. Involvement of microRNA-93, a new regulator of PTEN/Akt signaling pathway, in regulation of chemotherapeutic drug cisplatin chemosensitivity in ovarian cancer cells. FEBS Lett 2012;586:1279–86. 53. Yang H, Kong W, He L, et al. MicroRNA expression profiling in human ovarian cancer: miR-214 induces cell survival and cisplatin resistance by targeting PTEN. Cancer Res 2008;68:425–33. 54. Kong F, Sun C, Wang Z, et al. miR-125b confers resistance of ovarian cancer cells to cisplatin by targeting pro-apoptotic Bcl-2 antagonist killer 1. J Huazhong Univ Sci Technol Med Sci 2011;31: 543–9. 55. Yang N, Kaur S, Volinia S, et al. MicroRNA microarray identifies Let-7i as a novel biomarker and therapeutic target in human epithelial ovarian cancer. Cancer Res 2008;68:10307–14. 56. Liu N, Zhou C, Zhao J, Chen Y. Reversal of paclitaxel resistance in epithelial ovarian carcinoma cells by a MUC1 aptamer-let-7i chimera. Cancer Invest 2012;30:577–82. 57. Shen L, Cui J, Liang S, et al. Update of research on the role of EZH2 in cancer progression. Oncol Targets Ther 2013;6:321–4. 58. Hu S, Yu L, Li Z, et al. Overexpression of EZH2 contributes to acquired cisplatin resistance in ovarian cancer cells in vitro and in vivo. Cancer Biol Ther 2010;10:788–95.
Gynecol Endocrinol Downloaded from informahealthcare.com by Ondokuz Mayis Univ. on 05/20/14 For personal use only.
DOI: 10.3109/09513590.2013.871525
59. Kuang Y, Cai J, Li D, et al. Repression of Dicer is associated with invasive phenotype and chemoresistance in ovarian cancer. Oncol Lett 2013;5:1149–54. 60. Wang YQ, Guo RD, Guo RM, et al. MicroRNA-182 promotes cell growth, invasion and chemoresistance by targeting programmed cell death 4 (PDCD4) in human ovarian carcinomas. J Cell Biochem 2013;114:1464–73. 61. Huh JH, Kim TH, Kim K, et al. Dysregulation of miR-106a and miR-591 confers paclitaxel resistance to ovarian cancer. Br J Cancer 2013;109:452–61. 62. Cittelly DM, Dimitrova I, Howe EN, et al. Restoration of miR-200c to ovarian cancer reduces tumor burden and increases sensitivity to paclitaxel. Mol Cancer Ther 2012;11: 2556–65. 63. Leskela¨ S, Leandro-Garcı´a LJ, Mendiola M, et al. The miR-200 family controls beta-tubulin III expression and is associated with paclitaxel-based treatment response and progression-free survival in ovarian cancer patients. Endocr Relat Cancer 2010;18: 85–95. 64. Mitamura T, Watari H, Wang L, et al. Downregulation of miRNA-31 induces taxane resistance in ovarian cancer cells through increase of receptor tyrosine kinase MET. Oncogenesis 2013;2:e40.
Micro-RNAs and ovarian cancer
271
65. Bu R, Uddin S, Bavi P, et al. HGF/c-Met pathway has a prominent role in mediating antiapoptotic signals through AKT in epithelial ovarian carcinoma. Lab Invest 2011;91:124–37. 66. Zillhardt M, Park SM, Romero IL, et al. Foretinib (GSK1363089), an orally available multikinase inhibitor of c-Met and VEGFR-2, blocks proliferation, induces anoikis, and impairs ovarian cancer metastasis. Clin Cancer Res 2011;17:4042–51. 67. Neijenhuis S, Bajrami I, Miller R, et al. Identification of miRNA modulators to PARP inhibitor response. DNA Repair 2013;12: 394–402. 68. Marchini S, Cavalieri D, Fruscio R, et al. Association between miR200c and the survival of patients with stage I epithelial ovarian cancer: a retrospective study of two independent tumour tissue collections. Lancet Oncol 2011;12:273–85. 69. Hu X, Macdonald DM, Huettner PC, et al. A miR-200 microRNA cluster as prognostic marker in advanced ovarian cancer. Gynecol Oncol 2009;114:457–64. 70. Nam EJ, Yoon H, Kim SW, et al. MicroRNA expression profiles in serous ovarian carcinoma. Clin Cancer Res 2008;14: 2690–5. 71. Bentink S, Haibe-Kains B, Risch T, et al. Angiogenic mRNA and microRNA gene expression signature predicts a novel subtype of serous ovarian cancer. PLoS One 2012;7:e30269.
