Aberrant promoter methylation of CpG islands of tumor suppressor genes inhibits expression of the genes and may lead to tumorigenesis. We investigated the methylation profile of tumor associated genes CCND1, CDK5R2, PTP4A1,THY1 and CDK4 in hepatocellular carcinoma（HCC）and correlated the data with clinical findings. In order to understand the expression of CCND1, CDK5R2, PTP4A1, CDK4 and THY1 in human hepatocellular carcinoma. we examined 64 HCCs and their paired non-cancerous tissues by real-time quantitative reverse transcription-polymerase chain reaction and immunohistochemical analysis. The results showed that CCND1, CDK5R2, PTP4A1 and THY1 were underexpressed, while CDK4 was upregulated in most of the cancerous tissues. Methylation analysis of CpG sites at the promoter areas showed that THY1, PTP4A1 and CDK5R2 were methylated while CCND1 and CDK4 were not, thus confirming that the underexpression of THY1, PTP4A1 and CDK5R2 was due to aberrant DNA methylation. The mechanism of CCND1’s down regulation and CDK4’s upregulation in cancerous tissue need to be further studied
