Promoter methylation of RASSF1A gene in hepatocellular carcinoma and its clinical significance

Objective To explore the relationship between promoter methylation of RASSF1 A gene and clinico-pathological characteristics in hepatocellular carcinoma.Methods MS-PCR was used for analyzing the status of aberrant promoter methylation of RASSF1A in 100 primary HCC samples and adjacent noncancerous tissues,10 normal liver tissues,and six HCC cell lines.RT-PCR was used to assess reactivation of RASSF1A expression after HCC cell lines treated with demethylating agent 5'-aza-2' deoxycytideing.Results Abnormal promoter methylation of RASSF1A gene was found in 69(69％) cases of HCC,15 (15％) cases of adjacent normal tissues,and no abnormal promoter methylation of RASSF1A gene was found in normal liver tissues,and the difference was statistically significant (x2 =67.75,P ＜0.001).The methylation of RASSF1A gene was correlated to HBsAg (x2 =11.341,P ＜ 0.05) and histological differentiation(x2 =10.575,P ＜ 0.05).Four cell lines with abnormal CpG island methylation of RASSF1A gene were all re-expressed after treated with 5'-Aza-CdR.Conclusions RASSF1A gene promoter methylation was correlated to HBsAg and histological differentiation and this is one of the most important mechanism for low expression of RASSF1A in HCC. Key words: Carcinoma, hepatocellular;  DNA methylation;  RASSF1A