Promoter hypermethylation of PTPL1, PTPN6, DAPK, p16 and 5-azacitidine inhibits growth in DLBCL.
Aberrant hypermethylation of CpG islands of tumor suppressor is one of the mechanisms for epigenetic loss of gene function. In the present study, the methylation status of the promoter regions of protein tyrosine phosphatase (PTPN) 6, DAPK, and p16 were studied using methylation-specific polymerase chain reaction (MSP) in 26 diffuse large B cell lymphoma (DLBCL) lymphomas. In OCI-LY1 cell line, gene methylation status, expression of PTPL1 and its reactivation by DNA demethylation was determined by PCR and on the protein level by western blotting. ELISA-like reaction was used to detect global DNA methylation measurement. Induction of apoptosis by 5-azacitidine was analyzed by Annexin V/PI staining and flow cytometry. Our results show that hypermethylation of the PTPN6 gene promoter region was found in 15.4% (4/26), the DAPK gene promoter region in 30.8% (8/26), the p16 gene promoter region in 7.7% (2/26). Notably, we identified that PTPL1 was hypermethylated and transcriptionally silenced in OCI-LY1 cell line. The expression of PTPL1 was re-inducible by 5-azacytidine. 5-azacytidine also inhibits the proliferation and decreases the global methylation level of the OCI-LY1 cell line. We can conclude from our study that a higher prevalence of methylation of PTPL1, PTPN6, DAPK and p16 occur in DLBCL. Our data also highlights 5-azacytidine as a potential therapeutic candidate for DLBCL. Further studies are required to substantiate the role of methylation of PTPL1, PTPN6, DAPK and p16 as a marker in diffuse large B cell lymphoma.
Department of Hematology, Peking University Third Hospital, Beijing 100191, P.R. China.
Wenming
W
Wang
Department of Hematology, Peking University Third Hospital, Beijing 100191, P.R. China.
Jing
J
Wang
Department of Anesthesiology, Peking University Third Hospital, Beijing 100191, P.R. China.
Zhengqian
Z
Li
Department of Hematology, Peking University Third Hospital, Beijing 100191, P.R. China.
Mingxia
M
Zhu
Department of Urology, Peking University Third Hospital, Beijing 100191, P.R. China.
Zhe
Z
Zhang
Department of Hematology, Peking University Third Hospital, Beijing 100191, P.R. China.
Yanfang
Y
Wang
Department of Hematology, Peking University Third Hospital, Beijing 100191, P.R. China.
Hongmei
H
Jing
D001374:Azacitidine / Q000494:pharmacology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D019941:Cyclin-Dependent Kinase Inhibitor p16; D019175:DNA Methylation / Q000187:drug effects; D064550:Death-Associated Protein Kinases / Q000235:genetics*; D044127:Epigenesis, Genetic / Q000187:drug effects; D006801:Humans; D016403:Lymphoma, Large B-Cell, Diffuse / Q000235:genetics*; D009363:Neoplasm Proteins / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000187:drug effects; D054595:Protein Tyrosine Phosphatase, Non-Receptor Type 13 / Q000235:genetics* / Q000378:metabolism; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6 / Q000235:genetics*
C000614131:CDKN2A protein, human; D019941:Cyclin-Dependent Kinase Inhibitor p16; D009363:Neoplasm Proteins; C579096:DAPK1 protein, human; D064550:Death-Associated Protein Kinases; C516742:PTPN13 protein, human; C509249:PTPN6 protein, human; D054595:Protein Tyrosine Phosphatase, Non-Receptor Type 13; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D001374:Azacitidine