Promoter methylation and mRNA expression of DKK-3 and WIF-1 in hepatocellular carcinoma

Abstract

To investigate the promoter methylation status and mRNA expression of DKK-3 and WIF-1 gene in hepatocellular carcinoma (HCC). DKK-3 and WIF-1 acted as Wnt-antagonists and tumor suppressors, but hypermethylation of the gene promoter and low mRNA expression activated Wnt signaling aberrantly and induced the development of HCC. Methylation status of the DKK-3 and WIF-1 gene promoter was investigated using methylation specific polymerase chain reaction (PCR) in tumor and adjacent non-cancerous tissues from 33 HCC patients and 20 normal liver tissues served as control. The expression of DKK-3 and WIF-1 mRNA was also determined by real-time quantitative reverse transcriptase PCR. The relationship between methylation, mRNA expression, and clinical data, as well as methylation and mRNA expression of the two genes were analyzed. The methylation of DKK-3 and WIF-1 genes in HCC increased significantly compared with adjacent non-cancerous tissues and normal control tissues (chi(2) =7.79, P < 0.05; chi(2) = 4.89, P < 0.05), and no significant difference in methylation between adjacent non-cancerous tissues and normal control tissues was observed. In HCC tissues, significant differences in the DKK-3 promoter methylation were observed in age and cirrhosis, and significant differences of the WIF-1 promoter methylation were observed in HBsAg and cirrhosis. The average expression of DKK-3 mRNA in HCC and adjacent non-cancerous tissues was increased significantly compared with normal control tissues. The average expression of WIF-1 mRNA showed no significant difference among the three tissues. The mRNA expression of DKK-3 gene in HCC was decreased as the pathological grade increased. The aberrant promoter methylation and decreased expression of DKK-3 and WIF-1 may be an important mechanism in HCC, and may be a far-reaching significance in early diagnosis and therapy of HCC.