Purpose: CpG island methylator phenotype (CIMP) involves hypermethylation targeted toward the promoters of multiple genes. To gain insight into the role of epigenetic aberration of tumor-related genes in hepatocarcinogenesis, we determined a hypermethylation profile in hepatocellular carcinoma (HCC).
Experimental design: We examined the promoter methylation status of nine genes in 50 HCCs, 50 paired nontumor tissues, and 6 normal liver tissues by methylation-specific PCR. CIMP+ was defined as having five genes that are concordantly methylated.
Results: The frequency of promoter methylation of nine genes in 50 HCCs varied from 10% in P53 to 94% in c-Myc. The methylation status of P14, P15, P16, ER, RASSF1A, WT1, and c-Myc was significantly correlated with HCC and nontumor tissues (P<0.05). Hypermethylation of one or more genes was found in 96% of HCC. CIMP was more frequent in HCC than in nontumor tissues (70% and 12%, P<0.001). There is a significant association between CIMP and methylation of P14, P15, P16, ER, RSAAF1A, and WT1 (P<0.05) and serum alpha-fetoprotein (AFP) level (P=0.017). CIMP+ was more frequent in HCC with AFP>or=30 microg/L than those with AFP<30 microg/L (P=0.005). In addition, the promoter hypermethylation of P15 and P16 was associated with elevated serum AFP levels in 35 HCC samples with CIMP+ (P<0.05).
Conclusions: Positive correlation of CIMP and AFP levels in HCC suggests that CIMP can serve as a molecular marker of late-stage HCC development.