Promoter Methylation And MRNA Expression Of DKK-3 And WIF-1 Gene In Hepatocellular Carcinoma

objective: To investigate the promoter methylation status and mRNA expression of DKK-3 and WIF-1 gene in hepatocellular carcinoma.METHODS: Methylation status of DKK-3 and WIF-1 gene promoter were detected by methylation specific PCR in 33 hepatocellular carcinomas and adjacent non-cancerous tissues, 20 normal liver tissue as control. Expression of DKK-3 and WIF-1 mRNA was also determined by Real Time reverse transcriptase PCR in the three tissues. The relationship between methylation and clinical data, mRNA expression and clinical data, methylation and mRNA expression of the two genes were analyzed.RESULTS: DKK-3 promoter methylation was observed in 18/33, 7/33, 0/20 and WIF-1 promoter methylation was observed in 13/33, 5/33 and 0/20 in hepatocellular carcinomas, adjacent non-cancerous tissues and normal control tissues, respectively. Methylation of DKK-3 and WIF-1 genes in hepatocellular carcinoma increased significantly compared with adjacent non-cancerous tissues and normal control tissues (χ2 =7.79, P<0.05;χ2 =4.89, P<0.05)and there was no significant difference in methylation between adjacent non-cancerous tissues and normal control tissues. In HCC tissues, significant differences of the DKK-3 promoter methylation were observed in ages and cirrhosis, methylation of DKK-3 gene was significant more frequent in older (≥60 years) and non-cirrhotic patients than in younger(<60 years) and cirrhosis patients(P<0.05). Significant differences of the WIF-1 promoter methylation were observed in HBsAg infection and cirrhosis, methylation of WIF-1 gene was significant more frequent in HBsAg (-) and non-cirrhotic patients than in HBsAg (+) and cirrhotic patients(P<0.05). HCC recurrence rate in one year in patients with DKK-3 or WIF-1 methylation in HCC tissue was equivalency compared with whom without DKK-3 or WIF-1 methylation in HCC tissue in one year. Average expression of DKK-3 mRNA was 0.773±0.319,0.833±0.316 and 1.012±0.125 in hepatocellular carcinomas, adjacent non-cancerous tissues and normal control tissues, respectively. Average expression of DKK-3 mRNA in hepatocellular carcinomas and adjacent non-cancerous tissues was increased significantly compared with normal control tissues (P<0.05). Average expression of WIF-1 mRNA was 0.853±0.510,0.820±0.316 and 0.995±0.148, there was no significant difference among three tissues(P>0.05). Decreased expression of DKK-3 mRNA in hepatocellular carcinomas was correlated with pathological grade, and DKK-3 mRNA expression were more significantly in tumors which wasⅠ～Ⅱpathological grade than which wasⅢpathological grade in HCC tissues(P<0.05). There was no significant difference between expression of WIF-1 gene and clinical data. There was no correlation in methylation between DKK-3 gene and WIF-1 gene and also no correlation in expression between DKK-3 mRNA and WIF-1 mRNA in hepatocellular carcinomas and in adjacent non-cancerous tissues(P>0.05).Conclusion: Hypermethylation of DKK-3 and WIF-1 genes promoter and low expression of gene mRNA will activate Wnt signaling aberrantly, induce the development of HCC. But it is the other pathogenesis with hepatitis B (HBV) infection inducing the HCC development. Decreased expression of DKK-3 mRNA probably has effect on the invasion and intrahepatic metastasis of hepatocellular carcinoma.