Original Article
Copyright ©2012 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Gastroenterol. May 21, 2012; 18(19): 2334-2343
Published online May 21, 2012. doi: 10.3748/wjg.v18.i19.2334
Anti-tumor effect of 5-aza-2'-deoxycytidine by inhibiting telomerase activity in hepatocellular carcinoma cells
Shuang-Fen Tao, Chang-Song Zhang, Xian-Ling Guo, Yun Xu, Shan-Shan Zhang, Jian-Rui Song, Rong Li, Meng-Chao Wu, Li-Xin Wei
Shuang-Fen Tao, Chang-Song Zhang, Xian-Ling Guo, Yun Xu, Shan-Shan Zhang, Jian-Rui Song, Rong Li, Meng-Chao Wu, Li-Xin Wei, Tumor Immunology and Gene Therapy Center, Eastern Hepatobiliary Surgery Hospital, The Second Military Medical University, Shanghai 200438, China
Chang-Song Zhang, Clinical Oncology Laboratory, Changzhou Tumor Hospital, Medical College of Suzhou University, Changzhou 213001, Jiangsu Province, China
Author contributions: Tao SF, Zhang CS, Guo XL contributed equally to this work; Zhang CS and Guo XL designed the research; Xu Y, Zhang SS and Song JR performed the research; Li R and Wu MC analyzed the data; Tao SF and Wei LX wrote the paper.
Supported by The National Natural Science Foundation of China, No. 30901722, 30973433, 81000970, 81030041, 31171321 and 81101622
Correspondence to: Li-Xin Wei, MD, PhD, Tumor Immunology and Gene Therapy Center, Eastern Hepatobiliary Surgery Hospital, The Second Military Medical University, 225 Changhai Road, Shanghai 200438, China. lixinwei@smmu.edu.cn
Telephone: +86-21-81875331 Fax: +86-21-65566349
Received: July 8, 2011
Revised: December 7, 2011
Accepted: December 14, 2011
Published online: May 21, 2012
Abstract

AIM: To investigate the effect of the demethylating reagent 5-aza-2’-deoxycitidine (DAC) on telomerase activity in hepatocellular carcinoma (HCC) cell lines, SMMC-7721 and HepG2.

METHODS: The related gene expression in cell lines was examined by real-time reverse transcription-polymerase chain reaction and Western blotting analysis. The telomerase activity was examined by telomeric repeat amplification protocol-enzyme-linked immunosorbent assay and DNA methylation was determined by methylation-specific polymerase chain reaction.

RESULTS: The telomerase activity was significantly reduced in both cell lines treated with DAC, accompanied by downregulation of telomerase reverse transcriptase (hTERT). We also observed the effect of DAC on the methylation status of hTERT promoter and the expression of regulatory genes, such as c-myc, p15, p16, p21, E2F1, and WT1. The methylation status of hTERT promoter could be reversed in SMMC-7721 by DAC, but not in HepG2 cells. However, p16 expression could be reactivated by demethylation of its promoter, and c-Myc expression was repressed in both cell lines. Moreover, DAC could enhance the sensitivity to the chemotherapeutic agents, such as cisplatin, by induction of apoptosis of HCC cells.

CONCLUSION: The DAC exerts its anti-tumor effects in HCC cells by inhibiting the telomerase activity.

Keywords: 5-aza-2’-deoxycitidine; Telomerase; Hepatocellular carcinoma; DNA methylation