This article was downloaded by: [Michigan State University] On: 20 February 2015, At: 17:06 Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
Autophagy Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/kaup20
MicroRNA targets autophagy in pancreatic cancer cells during cancer therapy ab
c
ab
Peng Wang , Li Zhang , Zhen Chen
ab
& Zhiqiang Meng
a
Department of Integrative Oncology; Fudan University Shanghai Cancer Center; Shanghai, China b
Department of Oncology; Shanghai Medical College; Fudan University; Shanghai, China
c
Department of Neurology; Huadong Hospital; Fudan University; Shanghai, China Published online: 08 Oct 2013.
To cite this article: Peng Wang, Li Zhang, Zhen Chen & Zhiqiang Meng (2013) MicroRNA targets autophagy in pancreatic cancer cells during cancer therapy, Autophagy, 9:12, 2171-2172, DOI: 10.4161/auto.26463 To link to this article: http://dx.doi.org/10.4161/auto.26463
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
Autophagic Punctum
Autophagic Punctum
Autophagy 9:12, 2171–2172; December 2013; © 2013 Landes Bioscience
Peng Wang,1,2,† Li Zhang,3,† Zhen Chen,1,2,* and Zhiqiang Meng1,2,* Department of Integrative Oncology; Fudan University Shanghai Cancer Center; Shanghai, China; 2Department of Oncology; Shanghai Medical College; Fudan University; Shanghai, China; 3Department of Neurology; Huadong Hospital; Fudan University; Shanghai, China † These authors contributed equally to this work.
Downloaded by [Michigan State University] at 17:06 20 February 2015
1
T
Keywords: autophagy, microRNA, pancreatic cancer, radiosensitivity, ATG12 Submitted: 09/03/2013 Revised: 09/10/2013 Accepted: 09/11/2013 http://dx.doi.org/10.4161/auto.26463 *Correspondence to: Zhen Chen; Email: [email protected]; Zhiqiang Meng; Email: [email protected] Punctum to: Wang P, Zhang J, Zhang L, Zhu Z, Fan J, Chen L, Zhuang L, Luo J, Chen H, Liu L, et al. MicroRNA 23b Regulates Autophagy Associated With Radioresistance of Pancreatic Cancer Cells. Gastroenterology 2013; 145:1133–43. e12; PMID:23916944; http://dx.doi.org/10.1053/j. gastro.2013.07.048
he therapeutic outcome of pancreatic cancer is generally poor due to the inherent or acquired resistance of cancer cells to treatment. Pancreatic cancer cells have higher basal autophagy levels than other cancer cell types, which may correlate with their nonresponsiveness to the available cancer therapy. Therefore, understanding the mechanisms behind autophagy activation in pancreatic cancer cells may ultimately improve therapeutic outcomes. Here we demonstrated that MIR23B is a potent inhibitor of autophagy. MIR23B targets the 3´UTR of the autophagy-related gene ATG12, thereby decreasing autophagic activity and ultimately promoting radiation-induced pancreatic cancer cell death. Thus, our study clarified some of the underlying molecular mechanisms of activated autophagy in response to cancer therapy in pancreatic cancer. Autophagy is an evolutionarily conserved membrane-trafficking process that delivers cytoplasmic cargo to the lysosomes for digestion. This process is critical for maintaining cellular homeostasis as well as controlling cellular differentiation during development. Consequently, autophagy has become an important area of cancer research, and recent studies have shown that it plays dual contrasting roles in cancer cell biology. The absence or deficiency of autophagy genes enhances tumorigenesis, which suggests that autophagy functions as a mechanism for tumor suppression. However, autophagy may also contribute to tumor progression
by protecting cells from anticancer therapies. Increasing evidence indicates that autophagy is induced by the currently available cancer therapeutics, including chemotherapy, radiation therapy, and endocrine therapy, in both cell culture and animal models. Irradiation-induced autophagy protects cells from the cellular damage induced by radiation, thereby enhancing radioresistance. The mechanism by which autophagy is activated and its potential protective role in cancer cells remains unclear, however. In this study, we report that MIR23B plays a novel role as a key regulator of autophagy and that MIR 23B -inhibited /ATG12-mediated autophagy is a critical component of radioresistance. First, radioresistant cell lines were derived from human pancreatic cancer cell lines. We found that radioresistance in pancreatic cancer cells is accompanied by an increase in autophagic flux, whereas inhibiting autophagy by chloroquine, an inhibitor of the autophagy-lysosomal pathway, restores radiosensitivity. This suggests that autophagy antagonists can improve cancer therapy. Currently, the details of autophagy activation remain unclear. Thus, we investigated the signaling behind irradiation-induced autophagy and its role in cellular survival. Recent studies have confirmed that miRNA deregulation may contribute to many human diseases, including cancer. Several miRNAs have been used to predict and modify anticancer treatment, including radiotherapy. Therefore, we hypothesized that dysregulated miRNA expression may contribute
www.landesbioscience.com Autophagy 2171
©2013 Landes Bioscience. Do not distribute.
MicroRNA targets autophagy in pancreatic cancer cells during cancer therapy
cancer tissues. These results suggest that ATG12 is a key autophagy-related target regulated by MIR23B. In addition, we observered that inhibiting ATG12 significantly increases radiosensitivity in pancreatic cancer cells, and the radiosensitivity induced by MIR23B is abrogated by ATG12 overexpression. These effects were confirmed in a xenograft model, thereby suggesting that MIR23B-induced radiosensitivity depends on the suppression of ATG12. Thus, our study highlighted the role of MIR23B in autophagy modulation and suggests that MIR23B may have therapeutic uses for increasing radiosensitivity. Pancreatic cancer is the fourth leading cause of cancer-related death and has an overall 5-year survival rate of less than 5%. More than 80% of patients are diagnosed at late, inoperable stages and receive chemoradiation or targeted therapy. However, often these therapies fail to universally improve pancreatic cancer outcome due to the inherent chemoand radioresistance of pancreatic cancer. Pancreatic cancer cells have increased basal autophagy levels compared with other cancer cell types, which may correlate with their increased resistance to available cancer treatments. Therefore, three potential implications from our study can be envisioned. First, MIR23B expression levels are correlated with the radiosensitivity of pancreatic cancer cells to radiation treatment. Cells with higher MIR23B expression are more sensitive to radiation compared with cells with lower MIR23B expression. Therefore, evaluating MIR23B expression before initiating treatment may be a helpful predictor
2172 Autophagy
of radiosensitivity in patients. Second, chloroquine can increase radiation sensitivity when MIR23B expression is low. Chloroquine is already an FDA-approved drug. Therefore, pretreating patients who have low MIR23B expression with chloroquine may help improve the efficacy of current pancreatic cancer therapies, and evaluating MIR23B expression before radiation therapy may act as a good screening method. Finally, miRNAs may represent a novel drug target class. Delivering miRNAs that can posttranscriptionally reduce the protein levels of a disease’s target genes could represent a new therapeutic option. In summary, our study identified a role for MIR23B in autophagy modulation in pancreatic cancer cells. Future studies are necessary for evaluating its predictive value for a patient’s response to cancer therapy and to develop a more efficient and safer approach for delivering MIR23B in patients with pancreatic cancer. Disclosure of Potential Conflicts of Interest
No potential conflicts of interest were disclosed. Acknowledgments
This work was supported by the National Science Fundation of China (81001061 and 81370068 to PW); Shanghai Nature Science Fund, Shanghai, China (09ZR1406800 to PW); Shanghai Science and Technology Committee Rising-Star Program (11QA1401300 to PW); Medical Talents Training Program of Health Bureau of Shanghai (XYQ2011008 to PW); and Fudan University Zhuo-Xue Program (PW).
Volume 9 Issue 12
©2013 Landes Bioscience. Do not distribute.
Downloaded by [Michigan State University] at 17:06 20 February 2015
to autophagy activation and, eventually, radioresistance in pancreatic cancer cells. Using a microarray, we identified 15 miRNAs that are differentially expressed in radioresistant pancreatic cancer cells. We transfected cells with miRNA mimics or miRNA inhibitors for these miRNAs and found that MIR23B significantly inhibits autophagy activation in radioresistant cells. MIR23B overexpression increases intrinsic apoptotic events, such as cytochrome c release and CASP3/caspase 3 and CASP9 activation, in irradiated cells. In addition, MIR23B overexpression significantly decreases pancreatic cancer cell survival in cells exposed to radiation, whereas anti-MIR23B significantly increases radioresistance. Chloroquine, which inhibits the autophagy-lysosome pathway, does not augment the autophagy inhibition induced by MIR23B during irradiation. However, chloroquine significantly increases radiosensitivity when MIR23B expression is suppressed by antiMIR23B. Therefore, MIR23B plays a novel role in autophagy and radiosensitivity in pancreatic cancer cells. We also sought to identify a relevant MIR23B target that participates in MIR23B-mediated autophagy by assessing the effects of MIR23B on multiple autophagy-related genes. MIR23B markedly suppresses both the mRNA and protein expression of the gene autophagy-related 12 (ATG12). Two conserved MIR23B recognition sites in the 3′-UTR of ATG12 mediate this MIR23Binduced decrease in ATG12 expression. Furthermore, increased ATG12 expression is significantly correlated with the downregulation of MIR23 in human pancreatic
Autophagy Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/kaup20
MicroRNA targets autophagy in pancreatic cancer cells during cancer therapy ab
c
ab
Peng Wang , Li Zhang , Zhen Chen
ab
& Zhiqiang Meng
a
Department of Integrative Oncology; Fudan University Shanghai Cancer Center; Shanghai, China b
Department of Oncology; Shanghai Medical College; Fudan University; Shanghai, China
c
Department of Neurology; Huadong Hospital; Fudan University; Shanghai, China Published online: 08 Oct 2013.
To cite this article: Peng Wang, Li Zhang, Zhen Chen & Zhiqiang Meng (2013) MicroRNA targets autophagy in pancreatic cancer cells during cancer therapy, Autophagy, 9:12, 2171-2172, DOI: 10.4161/auto.26463 To link to this article: http://dx.doi.org/10.4161/auto.26463
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
Autophagic Punctum
Autophagic Punctum
Autophagy 9:12, 2171–2172; December 2013; © 2013 Landes Bioscience
Peng Wang,1,2,† Li Zhang,3,† Zhen Chen,1,2,* and Zhiqiang Meng1,2,* Department of Integrative Oncology; Fudan University Shanghai Cancer Center; Shanghai, China; 2Department of Oncology; Shanghai Medical College; Fudan University; Shanghai, China; 3Department of Neurology; Huadong Hospital; Fudan University; Shanghai, China † These authors contributed equally to this work.
Downloaded by [Michigan State University] at 17:06 20 February 2015
1
T
Keywords: autophagy, microRNA, pancreatic cancer, radiosensitivity, ATG12 Submitted: 09/03/2013 Revised: 09/10/2013 Accepted: 09/11/2013 http://dx.doi.org/10.4161/auto.26463 *Correspondence to: Zhen Chen; Email: [email protected]; Zhiqiang Meng; Email: [email protected] Punctum to: Wang P, Zhang J, Zhang L, Zhu Z, Fan J, Chen L, Zhuang L, Luo J, Chen H, Liu L, et al. MicroRNA 23b Regulates Autophagy Associated With Radioresistance of Pancreatic Cancer Cells. Gastroenterology 2013; 145:1133–43. e12; PMID:23916944; http://dx.doi.org/10.1053/j. gastro.2013.07.048
he therapeutic outcome of pancreatic cancer is generally poor due to the inherent or acquired resistance of cancer cells to treatment. Pancreatic cancer cells have higher basal autophagy levels than other cancer cell types, which may correlate with their nonresponsiveness to the available cancer therapy. Therefore, understanding the mechanisms behind autophagy activation in pancreatic cancer cells may ultimately improve therapeutic outcomes. Here we demonstrated that MIR23B is a potent inhibitor of autophagy. MIR23B targets the 3´UTR of the autophagy-related gene ATG12, thereby decreasing autophagic activity and ultimately promoting radiation-induced pancreatic cancer cell death. Thus, our study clarified some of the underlying molecular mechanisms of activated autophagy in response to cancer therapy in pancreatic cancer. Autophagy is an evolutionarily conserved membrane-trafficking process that delivers cytoplasmic cargo to the lysosomes for digestion. This process is critical for maintaining cellular homeostasis as well as controlling cellular differentiation during development. Consequently, autophagy has become an important area of cancer research, and recent studies have shown that it plays dual contrasting roles in cancer cell biology. The absence or deficiency of autophagy genes enhances tumorigenesis, which suggests that autophagy functions as a mechanism for tumor suppression. However, autophagy may also contribute to tumor progression
by protecting cells from anticancer therapies. Increasing evidence indicates that autophagy is induced by the currently available cancer therapeutics, including chemotherapy, radiation therapy, and endocrine therapy, in both cell culture and animal models. Irradiation-induced autophagy protects cells from the cellular damage induced by radiation, thereby enhancing radioresistance. The mechanism by which autophagy is activated and its potential protective role in cancer cells remains unclear, however. In this study, we report that MIR23B plays a novel role as a key regulator of autophagy and that MIR 23B -inhibited /ATG12-mediated autophagy is a critical component of radioresistance. First, radioresistant cell lines were derived from human pancreatic cancer cell lines. We found that radioresistance in pancreatic cancer cells is accompanied by an increase in autophagic flux, whereas inhibiting autophagy by chloroquine, an inhibitor of the autophagy-lysosomal pathway, restores radiosensitivity. This suggests that autophagy antagonists can improve cancer therapy. Currently, the details of autophagy activation remain unclear. Thus, we investigated the signaling behind irradiation-induced autophagy and its role in cellular survival. Recent studies have confirmed that miRNA deregulation may contribute to many human diseases, including cancer. Several miRNAs have been used to predict and modify anticancer treatment, including radiotherapy. Therefore, we hypothesized that dysregulated miRNA expression may contribute
www.landesbioscience.com Autophagy 2171
©2013 Landes Bioscience. Do not distribute.
MicroRNA targets autophagy in pancreatic cancer cells during cancer therapy
cancer tissues. These results suggest that ATG12 is a key autophagy-related target regulated by MIR23B. In addition, we observered that inhibiting ATG12 significantly increases radiosensitivity in pancreatic cancer cells, and the radiosensitivity induced by MIR23B is abrogated by ATG12 overexpression. These effects were confirmed in a xenograft model, thereby suggesting that MIR23B-induced radiosensitivity depends on the suppression of ATG12. Thus, our study highlighted the role of MIR23B in autophagy modulation and suggests that MIR23B may have therapeutic uses for increasing radiosensitivity. Pancreatic cancer is the fourth leading cause of cancer-related death and has an overall 5-year survival rate of less than 5%. More than 80% of patients are diagnosed at late, inoperable stages and receive chemoradiation or targeted therapy. However, often these therapies fail to universally improve pancreatic cancer outcome due to the inherent chemoand radioresistance of pancreatic cancer. Pancreatic cancer cells have increased basal autophagy levels compared with other cancer cell types, which may correlate with their increased resistance to available cancer treatments. Therefore, three potential implications from our study can be envisioned. First, MIR23B expression levels are correlated with the radiosensitivity of pancreatic cancer cells to radiation treatment. Cells with higher MIR23B expression are more sensitive to radiation compared with cells with lower MIR23B expression. Therefore, evaluating MIR23B expression before initiating treatment may be a helpful predictor
2172 Autophagy
of radiosensitivity in patients. Second, chloroquine can increase radiation sensitivity when MIR23B expression is low. Chloroquine is already an FDA-approved drug. Therefore, pretreating patients who have low MIR23B expression with chloroquine may help improve the efficacy of current pancreatic cancer therapies, and evaluating MIR23B expression before radiation therapy may act as a good screening method. Finally, miRNAs may represent a novel drug target class. Delivering miRNAs that can posttranscriptionally reduce the protein levels of a disease’s target genes could represent a new therapeutic option. In summary, our study identified a role for MIR23B in autophagy modulation in pancreatic cancer cells. Future studies are necessary for evaluating its predictive value for a patient’s response to cancer therapy and to develop a more efficient and safer approach for delivering MIR23B in patients with pancreatic cancer. Disclosure of Potential Conflicts of Interest
No potential conflicts of interest were disclosed. Acknowledgments
This work was supported by the National Science Fundation of China (81001061 and 81370068 to PW); Shanghai Nature Science Fund, Shanghai, China (09ZR1406800 to PW); Shanghai Science and Technology Committee Rising-Star Program (11QA1401300 to PW); Medical Talents Training Program of Health Bureau of Shanghai (XYQ2011008 to PW); and Fudan University Zhuo-Xue Program (PW).
Volume 9 Issue 12
©2013 Landes Bioscience. Do not distribute.
Downloaded by [Michigan State University] at 17:06 20 February 2015
to autophagy activation and, eventually, radioresistance in pancreatic cancer cells. Using a microarray, we identified 15 miRNAs that are differentially expressed in radioresistant pancreatic cancer cells. We transfected cells with miRNA mimics or miRNA inhibitors for these miRNAs and found that MIR23B significantly inhibits autophagy activation in radioresistant cells. MIR23B overexpression increases intrinsic apoptotic events, such as cytochrome c release and CASP3/caspase 3 and CASP9 activation, in irradiated cells. In addition, MIR23B overexpression significantly decreases pancreatic cancer cell survival in cells exposed to radiation, whereas anti-MIR23B significantly increases radioresistance. Chloroquine, which inhibits the autophagy-lysosome pathway, does not augment the autophagy inhibition induced by MIR23B during irradiation. However, chloroquine significantly increases radiosensitivity when MIR23B expression is suppressed by antiMIR23B. Therefore, MIR23B plays a novel role in autophagy and radiosensitivity in pancreatic cancer cells. We also sought to identify a relevant MIR23B target that participates in MIR23B-mediated autophagy by assessing the effects of MIR23B on multiple autophagy-related genes. MIR23B markedly suppresses both the mRNA and protein expression of the gene autophagy-related 12 (ATG12). Two conserved MIR23B recognition sites in the 3′-UTR of ATG12 mediate this MIR23Binduced decrease in ATG12 expression. Furthermore, increased ATG12 expression is significantly correlated with the downregulation of MIR23 in human pancreatic
