Epigenetic methylation and expression of caspase 8 and survivin in hepatocellular carcinoma

Caspase 8 and survivin are known as key molecules of apoptosis in hepatocellular carcinoma (HCC). The purpose of the present study was to investigate the relationship between promoter methylation and expression and apoptotic function of caspase 8 and survivin in HCC. Promoter methylation of the caspase 8 and survivin gene was analyzed in 73 primary HCC using methylation-specific polymerase chain reaction. The relationship between immunohistochemical expression of gene products and proliferative/apoptotic indices, and clinicopathological parameters was also investigated. Twenty-five (34%) and 24 (33%) patients had promoter methylation of caspase 8 and survivin gene. Immunohistochemical staining of caspase 8 and survivin was observed in 35 (48%) and 32 (44%). The methylation of caspase 8 and survivin demonstrated a negative correlation with immunohistochemical expression of gene products (P= 0.049 and P= 0.001). Methylation of caspase 8 and positive expression of its gene product was significantly correlated with high apoptotic indices (P= 0.032 and P= 0.026). Nuclear survivin expression was significantly correlated with high proliferative index (P= 0.001). On survival analysis, positive nuclear survivin expression was associated with a poor prognosis in HCC (P= 0.043). In conclusion, epigenetic alteration by promoter methylation of caspase 8 and survivin may constitute an important regulatory mechanism for expression of those genes in HCC.