[Promoter region methylation of DNA damage repair genes in human gastric cancer].

OBJECTIVE: To detect the status of promoter region methylation of damage repair genes in gastric cancer and analyze its association with clinicopathologic characteristics.

METHODS: A total of 70 human gastric cancer tissue samples representing all stages of disease were obtained from surgical resection specimens. DNA was extracted with the phenol-chloroform method. The technique of methylation specific polymerase chain reaction (MSP) was used to examine the methylation status of MLH1, CHFR, MGMT, FANCF, Rassf1A, BRCA1 and GSTpi in gastric cancer specimens. And MSP products were analyzed with 2% agarose gel electrophoresis.

RESULTS: The methylation rates of DNA damage related genes in human gastric cancer were as follows: MLH1 22.9% (16/70) , CHFR 47.1% (33/70), MGMT 34.3% (24/70), FANCF 11.4% (8/70), RASSF1A 7.1% (5/70), BRCA1 1.4% (1/70) and GSTpi 0% (0/70). And CHFR methylation was correlated with patient age (<60 year) (P = 0.035), tumor size (diameter ≥ 5 cm) (P = 0.031) and low differentiation (P = 0.019). In addition, CHFR methylation was associated with MLH1 methylation and MGMT methylation respectively.

CONCLUSION: In human gastric cancer, the DNA damage repair genes of MLH1, CHFR and MGMT are frequently methylated while FANCF, RASSF1A, BRCA1 and GSTpi infrequently. Thus MLH1, CHFR and MGMT may play important roles during carcinogenesis of gastric cancer. And these methylated genes may serve as potential detection markers for gastric cancer.