Expression of DNA-methyltransferases in hepatocellular carcinomas

Aims: Promoter methylation with subsequent inactivation of tumor suppressor genes is an important event in carcinogenesis. Maintance and de novo methylation are catalysed by DNMT methyltransferases DNMT1, DNMT3a and DNMT3b. Methods: Protein expression of DNMT1, DNMT3a and DNMT3b was performed in 35 hepatocellular carcinomas (HCC) and corresponding normal liver tissue using immunhistochemistry. DNMT expression was compared to promoter methylation of the tumorsuppressorgenes RASSF1A, BLU, SEMA3B, SOCS1, CDH1, CASP8 and GSTP1 detected by Methylation-specific PCR (MSP). Results: Increased protein expression of DNMT1…