Aberrant Promoter Methylation of the Vimentin Gene in Colorectal Cancer Associated with the Adenoma-Carcinoma Sequence

ABSTRACT

BACKGROUND: DNA hypermethylation is a common epigenetic finding in human cancers and is closely associated with transcriptional silencing. In the present study, we investigated the proportion of colorectal neoplasms that showed the adenoma-carcinoma progression and vimentin gene methylation. METHODS: Methylation status of the vimentin gene was examined in nontumoral mucosa, adenomas, and adenocarcinomas from 45 colorectal cancer patients who had adenoma and adenocarcinoma together. Methylation status was determined by bisulfite modification and the methylation-specific polymerase chain reaction. The expression of the vimentin gene product was also examined by immunohistochemistry. RESULTS: Promoter methylation of vimentin was detected in 80% (36 out of 45 cases) of adenocarcinomas, 82.2% (37 of 45) of adenomas, and 28.9% (13 of 45) of normal epithelia, and the difference between neoplastic and normal specimens was statistically significant (p < 0.001). However, no significant correlations were observed between methylation frequency and clinicopathologic variables. Immunohistochemically, vimentin expression was not observed in either normal epithelial cells or tumor cells. Protein expression and vimentin promoter methylation were not associated. CONCLUSIONS: The frequency of aberrant methylation of the vimentin gene was high in colonic adenomas and adenocarcinomas. This result suggests that the methylation status of vimentin may be clinically beneficial in screening for colorectal cancer patients and may be helpful in clarifying colorectal cancer biology.