Methylation-related silencing of p14ARF gene correlates with telomerase activity and mRNA expression of human telomerase reverse transcriptase in hepatocellular carcinoma
Zhang, C.; Guo, X.; Zhang, L.; Lu, Z.; Ma, N.; Cheng, Y.; Shen, F.; Zhang, B.; Wu, M.; Wei, L.
Journal of Surgical Oncology 98(6): 462-468
ISSN/ISBN: 1096-9098 PMID: 18683194 DOI: 10.1002/jso.21131
The p14(ARF) gene encodes a critical negative regulator of cell cycle progression. And upregulation of telomerase activity has been considered a critical step to tumors. We investigated promoter methylation of p14(ARF) and expression as well as their effect on hTERT expression and telomerase activity in HCC. We studied p14(ARF) methylation and mRNA in 30 hepatocellular carcinomas and corresponding non-tumor liver tissues using methylation-specific PCR. Reverse transcription-PCR was performed for expression of p14(ARF) and hTERT. Telomerase activity was performed by TRAP assay. p14(ARF) hypermethylation was detected in 16 (53.3%) of HCC and 10 (33.3%) of non-tumor tissues, and 12 of 16 with methylation were tumor tissues around large size (> or =5 cm). p14(ARF) mRNA was observed in 25%, 80.0%, or 50.0% of tumors with hypermethylated, partially methylated or unmethylated p14(ARF) promoter, respectively. Among the 16 tumors with p14(ARF) hypermethylation, all 12 tumors lacking p14(ARF) mRNA were positive for hTERT expression, while only one of 4 tumors expressing p14(ARF) mRNA was positive for hTERT expression. p14(ARF) hypermethylation may contribute to silencing of p14(ARF) mRNA expression in HCC. Telomerase activity is association with inactivation of the p14(ARF)-p53 pathway induced by methylation in HCC.