Effect of methylation of hMLH1 gene promotor on stage tumorigenesis and progression of human gastric cancer

Objective To illustrate the role of methylation level of hMLH1 gene promoter in different stages of gastric carcinogenesis by methylation-specific PCR (MSP) detection of samples from paracancerous tissue and gastric cancer tissue. Methods Methylation status of hMLH1 gene promoter of 40 patients undergoing radical stomach cancer operation in the Tumor Research Institute of China Medical University between January 2006 and August 2006 was detected by MSP. For each patient, 2 samples were chosen from the cancer site, paracancerous tissues of 1 cm, 3 cm, 5 cm away from the cancer site, separately. One sample was used in pathology examination, and the other in methylation detection. Results Positive rates of hMLH1 gene promoter methylation in the paracancerous tissues of 1 cm, 3 cm, 5 cm away from the cancer site were 10% (4/40), 12.5% (5/40) and 2.5% (1/40) respectively, which were significantly lower than 32.5% (13/40) in cancer site (all P 0.05). Conclusion Hypermethylation of hMLH1 gene promoter may be associated with the carcinogenesis stages and progression of human gastric cancer. Key words: Stomach neoplasms; hMLH1 gene; Methylation; Methylation-specific PCR