GENETIC TESTING AND MOLECULAR BIOMARKERS Volume 19, Number 4, 2015 ª Mary Ann Liebert, Inc. Pp. 1–3 DOI: 10.1089/gtmb.2014.0281
ORIGINAL ARTICLE
Does the Level of WT1 Expression Predict the Outcome in Philadelphia-Negative Myeloproliferative Neoplasms? Sener Tasdemir,1 Elif Funda Sener,2 Hilal Akalin,3 Muzaffer Keklik,4 Leyla Kaynar,4 and Yusuf Ozkul 3
Aims: Despite the clinical importance of the leukemic transformation of chronic myeloproliferative neoplasms (MPNs), very little is known about markers that predict leukemic transformation. We studied WT1 expression in 37 MPN patients diagnosed as bcr-abl negative and JAK2 (V617F) positive with a molecular genetic test, and 23 healthy controls. Results: WT1 expression is higher in MPN patients compared with normal controls ( p = 0.002). According to the WT1 expression levels, patients were divided into two groups: high ( ‡ 0.205) and low (0–0.205) WT1 expression. Two out of six patients with a high WT1 expression level transformed to myelodysplastic syndrome at a 42- and 46-month follow-up, respectively. Conclusions: Our results suggest that the overexpression of WT1 may play an important role in the leukemic transformation of MPNs.
is being tested for immunotherapy (Tamura et al., 2006; Yasukawa et al., 2009). In this study, we investigated whether or not WT1 gene expression is responsible for MPN transformation to leukemia.
Introduction
T
he 2008 World Health Organization classified myeloid neoplasm into five major categories: myeloproliferative neoplasm (MPN), PDGFR or FGFR1 rearranged myeloid/lymphoid neoplasms associated with eosinophilia, myelodysplastic syndromes (MDS), MDS/MPN, and acute myeloid leukemia (AML) (Tefferi et al., 2009). MPNs are hematological stem cell disorders with an increased mitotic rate, but without major maturation defects during the chronic stage (Haferlach et al., 2008). A single-point mutation in tyrosine kinase JAK2 (V617F), present in approximately 95% of patients with polycythemia vera (PV) and in 50–60% of patients with essential thrombocythemia (ET) and primary myelofibrosis, is considered to be an important factor for these diseases and has become a critical component of diagnostic criteria. MPN patients can transform into AML with variable frequencies preceded by a phase of myelofibrosis or MDS (Cervantes et al., 2008). Leukemic transformation occurs in 8–23% of MF patients in the first 10 years after diagnosis and in 4–8% of PV and ET patients within 18 years of diagnosis (Mesa et al., 2005; Tam et al., 2008; Kundranda et al., 2012). Although this transformation is a rare event, transformation to AML is associated with a poor response to therapy and short survival. Many parts of the molecular mechanisms involved in the pathogenesis of MPNs and their transformation to leukemia remain unknown (Perez et al., 2013). The Wilms tumor 1 gene (WT1) is an important factor in normal and malignant hematopoiesis. WT1 has already been used to guide therapy in patients with AML and MDS, and it 1 2
Materials and Methods
We studied 37 MPN patients diagnosed according to the 2008 World Health Organization criteria who were bcr-abl negative, JAK2 (V617F) positive using a molecular genetic test, and 23 healthy controls. The patients’ clinical characteristics are summarized in Table 1. RNA purification and cDNA synthesis
Total RNA was isolated from peripheral blood at the time of the MPN diagnosis after written informed consent had been obtained. Total RNA was isolated using an RNeasy mini kit (Qiagen) according to the manufacturer’s recommendations. RNA was transcribed into cDNA through random hexamer primers using the RevertAid First Strand cDNA Synthesis Kit (Fermentas). Synthesized cDNA was stored at - 80C. WT1 quantification by real-time quantitative PCR
Real-time PCR was performed in a Corbett Rotorgene RealTime PCR System. Quantitative WT1 expression was assessed using the ‘‘WT1 profileQuant kit’’ (Ipsogen) according to the manufacturer’s protocol. All samples were analyzed in duplicate. This kit measures the copy number of the ABL control and WT1 transcripts in human cell samples by generating standard curves based on a known concentration of plasmid
Department of Medical Genetics, Ataturk University, Erzurum, Turkey. Departments of Medical Biology, 3Medical Genetics, and 4Hematology, Erciyes University, Kayseri, Turkey.
1
2
TASDEMIR
Table 1. Patients’ Characteristics Clinical characteristics
Number
Patient number Male/Female Age, yeara Hb, g/dLa WBC, · 109/La Platelets, · 109/La Bcr/abl negative JAK2 (V617F) mutation Follow-up, montha Died Progression to AML Progression to MDS
37 20/17 63.8 13.7 11.3 337 37 37 42 4 0 2
a
Median range. AML, acute myeloid leukemia; Hb, hemoglobin; MDS, myelodysplastic syndromes; WBC, white blood cell.
dilutions of both the target and the control gene. The ratio of the WT1 transcript to the endogenous ABL concentration was calculated for each patient. Statistic
Comparisons between the patient and control group were made using the Mann–Whitney U test. A p value of < 0.05 was considered statistically significant. Statistical analysis was performed using IBM SPSS 15.0 software. Results
Clinical outcome data were available for 37 patients. There was no selection of patients. WT1 was detected in all the MPN samples and control groups. WT1 expression is higher in MPN cases compared with normal controls. The mean rate of WT1 expression in 37 cases of MNP was 0.205 compared with a mean expression of 0,017 in 23 controls. This difference was statistically significant ( p = 0.002). According to the distribution pattern of WT1 expression levels, patients were divided into two groups: high ( ‡ 0.205) and low (0– 0.205) WT1 expression. The patient characteristics of the high WT1 expression group, along with their clinical introduction, are given in Table 2. Two (patient nos. 28, 34) out of six patients’ progression to MDS at a 42- and 46-month follow-up, respectively, is shown. Discussion
The JAK2V617F mutation is associated with transformation to myelofibrosis for familial PV patients and probably for
ET patients as well, but it does not affect progression to AML (Malak et al., 2012). A significant number of patients with JAK2V617F mutant MPNs transform to a JAK2V617Fnegative secondary AML [sAML] (Campbell et al., 2006; Theocharides et al., 2007). This suggests the presence of other oncogenic alleles that precede JAK2V617F and/or promote leukemic transformation. Frequent mutations have been identified in JAK2, TET2, ASXL1, and IDH1 in sAML derived from MPN; with the exception of JAK2, the mutational frequency of these genes was similar in de novo and in sAML derived from MPN or MDS. The presence of concurrent mutations in TET2, ASXL1, and JAK2 in sAML suggests that these mutations make nonoverlapping contributions to myeloid transformation (Abdel-Wahab et al., 2010). The presence or absence of any one of these mutations involving JAK2, MPL, TET2, and ASXL1 is not associated with the survival or development of blast phase disease, myelofibrosis, or thrombosis. Associations exist between the JAK2V617F allele and its clinical results, but this still requires further validation. Also, its impact on treatment choices is not clear (Tefferi, 2010). The hematologic transformation of the MPN was responsible for 69% of the deaths, cerebral stroke was responsible for 7%, and 4% died of myocardial infarction (Malak et al., 2012). The WT1 transcription factor is extremely important in the regulation of apoptosis, proliferation, and differentiation. WT1 is an aberrantly overexpressed transcription factor found in many human malignancies, including acute and chronic leukemias. WT1 plays a role in hematopoiesis, serving to maintain the self-renewal of primitive CD34 + cells in the bone marrow (Ariyaratana and Loeb, 2007). As differentiation proceeds, WT1 is downregulated and is not expressed in mature blood cells. Thus, it has been suggested that in leukemia, WT1 contributes to the maintenance of the dedifferentiated state and promotes proliferation (Yang et al., 2007). The Wilms’ tumor gene is highly expressed in MDS hematopoietic cells (Cilloni et al., 2003, 2006). It is interesting that the progression of malignant disorders is associated with the increased expression of the tumor suppression gene. WT1 appears to play a role in the MDS process that is very different from that of other known tumor suppression genes (Li et al., 2007). Conflicting reports exist regarding the differential expression of WT1 isoforms in leukemic cells. An increasing volume of literature has illuminated the significance of isoform-specific roles in cellular differentiation and proliferation. WT1’s role in leukemogenesis is yet to be fully clarified, but it is likely isoform specific as well (Ariyaratana and Loeb, 2007).
Table 2. Clinical Data of High WT1 Expression Group Patient no.
Sex
Hb Age (g/dL)
2 4 11 16 28 34
F M F F M F
73 78 63 57 67 71
17.5 15.4 13.2 12.3 11 8.5
WBC Plt WT1/abl ( · 109/L) ( · 109/L) mRNA level 15.6 24.74 29.51 13.07 14.47 21.07
CVD, cardiovascular disease; Plt, platelets.
623,000 396,000 208,000 205,000 358,000 170,000
0.7 1.06 0.68 3.5 0.25 0.905
Treatment Supportive Hydrea Hydrea Hydrea Hydrea Hydrea
Follow-up Progression (month) to MDS/AML 41 51 52 37 42 46
— — — — MDS MDS
Present Died (CVD) Live Live Live Live Live
WT1 EXPRESSION IN MYELOPROLIFERATIVE NEOPLASMS
In the recent study, WT1 expression is higher in MPN patients compared with controls. Also, two patients experienced high-level WT1 expression progression to MDS at a 42- and 46-month follow-up, respectively. Transient myeloproliferative disorder (TMD) is found in 10% of newborns with Down syndrome. In 20–30% of cases of regressed Down syndrome TMD, the dormant clonal TMD is thought to accumulate additional changes and cause acute megakaryoblastic leukemia 1–4 years later (Malinge et al., 2009), in 70% of cases preceded by an MDS-like stage (Wechsler et al., 2002). WT1 gene expression in children with Down syndrome and TMD has been analyzed. WT1 expression may be such a marker acting as a surrogate molecular marker for malignant cells. WT1 expression may be used to monitor patients following TMD and to identify those with an increased risk of subsequent myeloid leukemia (Hasle et al., 2006). Our results suggest that the overexpression of WT1 may play an important role in the leukemic transformation of MPNs. More research is needed to identify the WT1 isoforms’ role, and WT1 gene methylation studies must be done for classic Philadelphia-negative MPNs and the leukemic transformation. It may identify patients with an increased risk of subsequent myeloid leukemia and be useful for targeting WT1 to design targeted therapies for these patients. Acknowledgment
The authors thank Asst. Prof. Yasemin Cayir for the statistical analysis. Author Disclosure Statement
All authors have no competing financial interests. References
Abdel-Wahab O, Manshouri T, Patel J, et al. (2010) Genetic analysis of transforming events that convert chronic myeloproliferative neoplasms to leukemias. Cancer Res 70:447– 452. Ariyaratana S, Loeb DM (2007) The role of the Wilms tumour gene (WT1) in normal and malignant haematopoiesis. Expert Rev Mol Med 9:1–17. Campbell PJ, Baxter EJ, Beer PA, et al. (2006) Mutation of JAK2 in the myeloproliferative disorders: timing, clonality studies, cytogenetic associations, and role in leukemic transformation. Blood 108:3548–3555. Cervantes F, Passamonti F, Barosi G. (2008) Life expectancy and prognostic factors in the classic BCR/ABL-negative myeloproliferative disorders. Leukemia 22:905–914. Cilloni D, Gottardi E, Messa F, et al. (2003) Significant correlation between the degree of WT1 expression and the International Prognostic Scoring System Score in patients with myelodysplastic syndromes. J Clin Oncol 21:1988–1995. Cilloni D, Gottardi E, Saglio G. (2006) WT1 overexpression in acute myeloid leukemia and myelodysplastic syndromes. Methods Mol Med 125:199–211. Haferlach T, Bacher U, Kern W, et al. (2008) The diagnosis of BCR/ ABL-negative chronic myeloproliferative diseases (CMPD): a comprehensive approach based on morphology, cytogenetics, and molecular markers. Ann Hematol 87:1–10.
3
Hasle H, Lund B, Nyvold CG, et al. (2006) WT1 gene expression in children with Down syndrome and transient myeloproliferative disorder. Leuk Res 30:543–546. Kundranda MN, Tibes R, Mesa RA (2012) Transformation of a chronic myeloproliferative neoplasm to acute myelogenous leukemia: does anything work? Curr Hematol Malig Rep 7:78–86. Li X, Wu L, Ying S, et al. (2007) Wilms’ tumor gene (WT1) is predominantly expressed in clonal hematopoietic cells in myelodysplastic syndromes. Leuk Lymphoma 48:601–604. Malak S, Labopin M, Saint-Martin C, et al. (2012) Long term follow up of 93 families with myeloproliferative neoplasms: life expectancy and implications of JAK2V617F in the occurrence of complications. Blood Cells Mol Dis 49:170–176. Malinge S, Izraeli S, Crispino JD (2009) Insights into the manifestations, outcomes, and mechanisms of leukemogenesis in Down syndrome. Blood 113:2619–2628. Mesa RA, Li CY, Ketterling RP, et al. (2005) Leukemic transformation in myelofibrosis with myeloid metaplasia: a singleinstitution experience with 91 cases. Blood 105:973–977. Perez C, Pascual M, Martin-Subero JI, et al. (2013) Aberrant DNA methylation profile of chronic and transformed classic Philadelphia-negative myeloproliferative neoplasms. Haematologica 98:1414–1420. Tam CS, Nussenzveig RM, Popat U, et al. (2008) The natural history and treatment outcome of blast phase BCR-ABLmyeloproliferative neoplasms. Blood 112:1628–1637. Tamura K, Kanazawa T, Suzuki M, et al. (2006) Successful rapid discontinuation of immunosuppressive therapy at molecular relapse after allogeneic bone marrow transplantation in a pediatric patient with myelodysplastic syndrome. Am J Hematol 81:139–141. Tefferi A (2010) Mutational analysis in BCR-ABL-negative classic myeloproliferative neoplasms: impact on prognosis and therapeutic choices. Leuk Lymphoma 51:576–582. Tefferi A, Thiele J, Vardiman JW (2009) The 2008 World Health Organization classification system for myeloproliferative neoplasms: order out of chaos. Cancer 115:3842–3847. Theocharides A, Boissinot M, Girodon F, et al. (2007) Leukemic blasts in transformed JAK2-V617F-positive myeloproliferative disorders are frequently negative for the JAK2-V617F mutation. Blood 110:375–379. Wechsler J, Greene M, McDevitt MA, et al. (2002) Acquired mutations in GATA1 in the megakaryoblastic leukemia of Down syndrome. Nat Genet 32:148–152. Yang L, Han Y, Suarez Saiz F, et al. (2007). A tumor suppressor and oncogene: the WT1 story. Leukemia 21:868–876. Yasukawa M, Fujiwara H, Ochi T, et al. (2009) Clinical efficacy of WT1 peptide vaccination in patients with acute myelogenous leukemia and myelodysplastic syndrome. Am J Hematol 84:314–315.
Address correspondence to: Sener Tasdemir, MD Department of Medical Genetics Ataturk University Erzurum 25240 Turkey E-mail: [email protected]
ORIGINAL ARTICLE
Does the Level of WT1 Expression Predict the Outcome in Philadelphia-Negative Myeloproliferative Neoplasms? Sener Tasdemir,1 Elif Funda Sener,2 Hilal Akalin,3 Muzaffer Keklik,4 Leyla Kaynar,4 and Yusuf Ozkul 3
Aims: Despite the clinical importance of the leukemic transformation of chronic myeloproliferative neoplasms (MPNs), very little is known about markers that predict leukemic transformation. We studied WT1 expression in 37 MPN patients diagnosed as bcr-abl negative and JAK2 (V617F) positive with a molecular genetic test, and 23 healthy controls. Results: WT1 expression is higher in MPN patients compared with normal controls ( p = 0.002). According to the WT1 expression levels, patients were divided into two groups: high ( ‡ 0.205) and low (0–0.205) WT1 expression. Two out of six patients with a high WT1 expression level transformed to myelodysplastic syndrome at a 42- and 46-month follow-up, respectively. Conclusions: Our results suggest that the overexpression of WT1 may play an important role in the leukemic transformation of MPNs.
is being tested for immunotherapy (Tamura et al., 2006; Yasukawa et al., 2009). In this study, we investigated whether or not WT1 gene expression is responsible for MPN transformation to leukemia.
Introduction
T
he 2008 World Health Organization classified myeloid neoplasm into five major categories: myeloproliferative neoplasm (MPN), PDGFR or FGFR1 rearranged myeloid/lymphoid neoplasms associated with eosinophilia, myelodysplastic syndromes (MDS), MDS/MPN, and acute myeloid leukemia (AML) (Tefferi et al., 2009). MPNs are hematological stem cell disorders with an increased mitotic rate, but without major maturation defects during the chronic stage (Haferlach et al., 2008). A single-point mutation in tyrosine kinase JAK2 (V617F), present in approximately 95% of patients with polycythemia vera (PV) and in 50–60% of patients with essential thrombocythemia (ET) and primary myelofibrosis, is considered to be an important factor for these diseases and has become a critical component of diagnostic criteria. MPN patients can transform into AML with variable frequencies preceded by a phase of myelofibrosis or MDS (Cervantes et al., 2008). Leukemic transformation occurs in 8–23% of MF patients in the first 10 years after diagnosis and in 4–8% of PV and ET patients within 18 years of diagnosis (Mesa et al., 2005; Tam et al., 2008; Kundranda et al., 2012). Although this transformation is a rare event, transformation to AML is associated with a poor response to therapy and short survival. Many parts of the molecular mechanisms involved in the pathogenesis of MPNs and their transformation to leukemia remain unknown (Perez et al., 2013). The Wilms tumor 1 gene (WT1) is an important factor in normal and malignant hematopoiesis. WT1 has already been used to guide therapy in patients with AML and MDS, and it 1 2
Materials and Methods
We studied 37 MPN patients diagnosed according to the 2008 World Health Organization criteria who were bcr-abl negative, JAK2 (V617F) positive using a molecular genetic test, and 23 healthy controls. The patients’ clinical characteristics are summarized in Table 1. RNA purification and cDNA synthesis
Total RNA was isolated from peripheral blood at the time of the MPN diagnosis after written informed consent had been obtained. Total RNA was isolated using an RNeasy mini kit (Qiagen) according to the manufacturer’s recommendations. RNA was transcribed into cDNA through random hexamer primers using the RevertAid First Strand cDNA Synthesis Kit (Fermentas). Synthesized cDNA was stored at - 80C. WT1 quantification by real-time quantitative PCR
Real-time PCR was performed in a Corbett Rotorgene RealTime PCR System. Quantitative WT1 expression was assessed using the ‘‘WT1 profileQuant kit’’ (Ipsogen) according to the manufacturer’s protocol. All samples were analyzed in duplicate. This kit measures the copy number of the ABL control and WT1 transcripts in human cell samples by generating standard curves based on a known concentration of plasmid
Department of Medical Genetics, Ataturk University, Erzurum, Turkey. Departments of Medical Biology, 3Medical Genetics, and 4Hematology, Erciyes University, Kayseri, Turkey.
1
2
TASDEMIR
Table 1. Patients’ Characteristics Clinical characteristics
Number
Patient number Male/Female Age, yeara Hb, g/dLa WBC, · 109/La Platelets, · 109/La Bcr/abl negative JAK2 (V617F) mutation Follow-up, montha Died Progression to AML Progression to MDS
37 20/17 63.8 13.7 11.3 337 37 37 42 4 0 2
a
Median range. AML, acute myeloid leukemia; Hb, hemoglobin; MDS, myelodysplastic syndromes; WBC, white blood cell.
dilutions of both the target and the control gene. The ratio of the WT1 transcript to the endogenous ABL concentration was calculated for each patient. Statistic
Comparisons between the patient and control group were made using the Mann–Whitney U test. A p value of < 0.05 was considered statistically significant. Statistical analysis was performed using IBM SPSS 15.0 software. Results
Clinical outcome data were available for 37 patients. There was no selection of patients. WT1 was detected in all the MPN samples and control groups. WT1 expression is higher in MPN cases compared with normal controls. The mean rate of WT1 expression in 37 cases of MNP was 0.205 compared with a mean expression of 0,017 in 23 controls. This difference was statistically significant ( p = 0.002). According to the distribution pattern of WT1 expression levels, patients were divided into two groups: high ( ‡ 0.205) and low (0– 0.205) WT1 expression. The patient characteristics of the high WT1 expression group, along with their clinical introduction, are given in Table 2. Two (patient nos. 28, 34) out of six patients’ progression to MDS at a 42- and 46-month follow-up, respectively, is shown. Discussion
The JAK2V617F mutation is associated with transformation to myelofibrosis for familial PV patients and probably for
ET patients as well, but it does not affect progression to AML (Malak et al., 2012). A significant number of patients with JAK2V617F mutant MPNs transform to a JAK2V617Fnegative secondary AML [sAML] (Campbell et al., 2006; Theocharides et al., 2007). This suggests the presence of other oncogenic alleles that precede JAK2V617F and/or promote leukemic transformation. Frequent mutations have been identified in JAK2, TET2, ASXL1, and IDH1 in sAML derived from MPN; with the exception of JAK2, the mutational frequency of these genes was similar in de novo and in sAML derived from MPN or MDS. The presence of concurrent mutations in TET2, ASXL1, and JAK2 in sAML suggests that these mutations make nonoverlapping contributions to myeloid transformation (Abdel-Wahab et al., 2010). The presence or absence of any one of these mutations involving JAK2, MPL, TET2, and ASXL1 is not associated with the survival or development of blast phase disease, myelofibrosis, or thrombosis. Associations exist between the JAK2V617F allele and its clinical results, but this still requires further validation. Also, its impact on treatment choices is not clear (Tefferi, 2010). The hematologic transformation of the MPN was responsible for 69% of the deaths, cerebral stroke was responsible for 7%, and 4% died of myocardial infarction (Malak et al., 2012). The WT1 transcription factor is extremely important in the regulation of apoptosis, proliferation, and differentiation. WT1 is an aberrantly overexpressed transcription factor found in many human malignancies, including acute and chronic leukemias. WT1 plays a role in hematopoiesis, serving to maintain the self-renewal of primitive CD34 + cells in the bone marrow (Ariyaratana and Loeb, 2007). As differentiation proceeds, WT1 is downregulated and is not expressed in mature blood cells. Thus, it has been suggested that in leukemia, WT1 contributes to the maintenance of the dedifferentiated state and promotes proliferation (Yang et al., 2007). The Wilms’ tumor gene is highly expressed in MDS hematopoietic cells (Cilloni et al., 2003, 2006). It is interesting that the progression of malignant disorders is associated with the increased expression of the tumor suppression gene. WT1 appears to play a role in the MDS process that is very different from that of other known tumor suppression genes (Li et al., 2007). Conflicting reports exist regarding the differential expression of WT1 isoforms in leukemic cells. An increasing volume of literature has illuminated the significance of isoform-specific roles in cellular differentiation and proliferation. WT1’s role in leukemogenesis is yet to be fully clarified, but it is likely isoform specific as well (Ariyaratana and Loeb, 2007).
Table 2. Clinical Data of High WT1 Expression Group Patient no.
Sex
Hb Age (g/dL)
2 4 11 16 28 34
F M F F M F
73 78 63 57 67 71
17.5 15.4 13.2 12.3 11 8.5
WBC Plt WT1/abl ( · 109/L) ( · 109/L) mRNA level 15.6 24.74 29.51 13.07 14.47 21.07
CVD, cardiovascular disease; Plt, platelets.
623,000 396,000 208,000 205,000 358,000 170,000
0.7 1.06 0.68 3.5 0.25 0.905
Treatment Supportive Hydrea Hydrea Hydrea Hydrea Hydrea
Follow-up Progression (month) to MDS/AML 41 51 52 37 42 46
— — — — MDS MDS
Present Died (CVD) Live Live Live Live Live
WT1 EXPRESSION IN MYELOPROLIFERATIVE NEOPLASMS
In the recent study, WT1 expression is higher in MPN patients compared with controls. Also, two patients experienced high-level WT1 expression progression to MDS at a 42- and 46-month follow-up, respectively. Transient myeloproliferative disorder (TMD) is found in 10% of newborns with Down syndrome. In 20–30% of cases of regressed Down syndrome TMD, the dormant clonal TMD is thought to accumulate additional changes and cause acute megakaryoblastic leukemia 1–4 years later (Malinge et al., 2009), in 70% of cases preceded by an MDS-like stage (Wechsler et al., 2002). WT1 gene expression in children with Down syndrome and TMD has been analyzed. WT1 expression may be such a marker acting as a surrogate molecular marker for malignant cells. WT1 expression may be used to monitor patients following TMD and to identify those with an increased risk of subsequent myeloid leukemia (Hasle et al., 2006). Our results suggest that the overexpression of WT1 may play an important role in the leukemic transformation of MPNs. More research is needed to identify the WT1 isoforms’ role, and WT1 gene methylation studies must be done for classic Philadelphia-negative MPNs and the leukemic transformation. It may identify patients with an increased risk of subsequent myeloid leukemia and be useful for targeting WT1 to design targeted therapies for these patients. Acknowledgment
The authors thank Asst. Prof. Yasemin Cayir for the statistical analysis. Author Disclosure Statement
All authors have no competing financial interests. References
Abdel-Wahab O, Manshouri T, Patel J, et al. (2010) Genetic analysis of transforming events that convert chronic myeloproliferative neoplasms to leukemias. Cancer Res 70:447– 452. Ariyaratana S, Loeb DM (2007) The role of the Wilms tumour gene (WT1) in normal and malignant haematopoiesis. Expert Rev Mol Med 9:1–17. Campbell PJ, Baxter EJ, Beer PA, et al. (2006) Mutation of JAK2 in the myeloproliferative disorders: timing, clonality studies, cytogenetic associations, and role in leukemic transformation. Blood 108:3548–3555. Cervantes F, Passamonti F, Barosi G. (2008) Life expectancy and prognostic factors in the classic BCR/ABL-negative myeloproliferative disorders. Leukemia 22:905–914. Cilloni D, Gottardi E, Messa F, et al. (2003) Significant correlation between the degree of WT1 expression and the International Prognostic Scoring System Score in patients with myelodysplastic syndromes. J Clin Oncol 21:1988–1995. Cilloni D, Gottardi E, Saglio G. (2006) WT1 overexpression in acute myeloid leukemia and myelodysplastic syndromes. Methods Mol Med 125:199–211. Haferlach T, Bacher U, Kern W, et al. (2008) The diagnosis of BCR/ ABL-negative chronic myeloproliferative diseases (CMPD): a comprehensive approach based on morphology, cytogenetics, and molecular markers. Ann Hematol 87:1–10.
3
Hasle H, Lund B, Nyvold CG, et al. (2006) WT1 gene expression in children with Down syndrome and transient myeloproliferative disorder. Leuk Res 30:543–546. Kundranda MN, Tibes R, Mesa RA (2012) Transformation of a chronic myeloproliferative neoplasm to acute myelogenous leukemia: does anything work? Curr Hematol Malig Rep 7:78–86. Li X, Wu L, Ying S, et al. (2007) Wilms’ tumor gene (WT1) is predominantly expressed in clonal hematopoietic cells in myelodysplastic syndromes. Leuk Lymphoma 48:601–604. Malak S, Labopin M, Saint-Martin C, et al. (2012) Long term follow up of 93 families with myeloproliferative neoplasms: life expectancy and implications of JAK2V617F in the occurrence of complications. Blood Cells Mol Dis 49:170–176. Malinge S, Izraeli S, Crispino JD (2009) Insights into the manifestations, outcomes, and mechanisms of leukemogenesis in Down syndrome. Blood 113:2619–2628. Mesa RA, Li CY, Ketterling RP, et al. (2005) Leukemic transformation in myelofibrosis with myeloid metaplasia: a singleinstitution experience with 91 cases. Blood 105:973–977. Perez C, Pascual M, Martin-Subero JI, et al. (2013) Aberrant DNA methylation profile of chronic and transformed classic Philadelphia-negative myeloproliferative neoplasms. Haematologica 98:1414–1420. Tam CS, Nussenzveig RM, Popat U, et al. (2008) The natural history and treatment outcome of blast phase BCR-ABLmyeloproliferative neoplasms. Blood 112:1628–1637. Tamura K, Kanazawa T, Suzuki M, et al. (2006) Successful rapid discontinuation of immunosuppressive therapy at molecular relapse after allogeneic bone marrow transplantation in a pediatric patient with myelodysplastic syndrome. Am J Hematol 81:139–141. Tefferi A (2010) Mutational analysis in BCR-ABL-negative classic myeloproliferative neoplasms: impact on prognosis and therapeutic choices. Leuk Lymphoma 51:576–582. Tefferi A, Thiele J, Vardiman JW (2009) The 2008 World Health Organization classification system for myeloproliferative neoplasms: order out of chaos. Cancer 115:3842–3847. Theocharides A, Boissinot M, Girodon F, et al. (2007) Leukemic blasts in transformed JAK2-V617F-positive myeloproliferative disorders are frequently negative for the JAK2-V617F mutation. Blood 110:375–379. Wechsler J, Greene M, McDevitt MA, et al. (2002) Acquired mutations in GATA1 in the megakaryoblastic leukemia of Down syndrome. Nat Genet 32:148–152. Yang L, Han Y, Suarez Saiz F, et al. (2007). A tumor suppressor and oncogene: the WT1 story. Leukemia 21:868–876. Yasukawa M, Fujiwara H, Ochi T, et al. (2009) Clinical efficacy of WT1 peptide vaccination in patients with acute myelogenous leukemia and myelodysplastic syndrome. Am J Hematol 84:314–315.
Address correspondence to: Sener Tasdemir, MD Department of Medical Genetics Ataturk University Erzurum 25240 Turkey E-mail: [email protected]
