Mapping and analysis of the methylation variable positions profiles of hMLH1 promoter CpG islands in human sporadic colorectal carcinoma / 第三军医大学学报

ABSTRACT

Objective To map the complete methylation status of the hMLH1 promoter in sporadic colorectal carcinoma and analyze the relationship between MVPs (methylation variable positions) of hMLH1 promoter and the expression of hMLH1. Methods Methylation status of hMLH1 promoter was measured by bisulfite sequencing. hMLH1 protein expression was detected by immunohistochemistry. Results Out of the 30 sporadic colorectal carcinoma specimens, the hypermethylation of CGIs (CpG islands) 1 was in 6 and that of CGIs 2 in 4. The hMLH1 protein was detected in 15 specimens. Chi square test showed the methylation of CGIs 1 was closely related to loss of hMLH1 protein expression (P0.05). Conclusion In CGIs 1, CpG positions from 1 to 28 are the critical region that could influence the expression of hMLH1.