Effects of 5-Aza-deoxycitydine on Proliferation of Bladder Cancer Cell Lines and Abnormal Methylation of hsa-miR-203

Abstract: The inactivation of miRNAs in tumors is related to specific genetic or epigenetic alterations according to the studies recently. hsa-miR-203， as a tumor suppessor gene， is down-regulated in bladder cancer tissues and bladder tumor cells. In order to study whether miR-203 is downregulated by DNA hypermethylation， bladder cancer cell lines 5637 and BIU-87 were treated by methylase inhibitor 5-Aza-2-deoxycytidine (5-Aza-CdR). By using MSP and RT-PCR， it indicated that the promoter of hsa-miR-203 is hypermethylated in 5637 and BIU-87. However， 5-Aza-CdR can reverse the aberrant hypermethylation of hsa-miR-203’s promoter and induce has-miR-203 expression. Moreover， 5-Aza-CdR displayed a growth inhitory effect on 5637 and BIU-87 cells in a dose- and timedependent manner after exposure to 5-Aza-CdR at different concentrations for different time. FCM analysis showed that cell cycles of 5637 and BIU-87 cells were blocked at G0/G1 phase after 5-Aza-CdR treatment for 72 hours. Taken together， bladder cancer cell lines 5637 and BIU-87 cell growth could be inhibited and cell cycles could be blocked by 5-Aza-CdR. Hypermethylation of hsa-miR-203 promoter is an important mechanism of hsa-miR-203 down regulation in bladder cancer cell lines. Methylation could be reversed and hsa-miR-203 expression could be induced by 5-Aza-CdR. All of the above implies that hsa-miR-203 may serve as a demethylation therapeutic target in bladder cancer.

CSTR: 32200.14.cjcb.2011.07.0006