title: [Effect of methylation of hMLH1 gene promotor on stage tumorigenesis and progression of human gastric cancer].
abstract: 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). Pathological examination showed precancerous lesions in 23 samples of paracancerous 1 cm and 3 cm tissues and normal tissues in 24 samples of paracancerous 5 cm tissues. Positive rates of hMLH1 gene promoter methylation in the cancer site, paracancerous tissue and normal gastric tissue were 32.5%(13/40), 8.7%(2/23) and 0(0/24) (P<0.01). For cancer tissue penetrated the gastric serosa, 8 out of 14 tissue samples were positive methylation (57.1%), which was significantly higher compared with 5 out of 26 tissue samples without penetration of gastric serosa(19.2%). Positive rate of hMLH1 gene promoter methylation in tissue samples with 7 or more of metastatic lymphatic node number was 61.5%(8/13), which was higher compared to that with less than 7(5/27, 18.5%) (P<0.05). No significant differences of positive rate of hMLH1 gene promoter methylation were found between different tumor gross types, tumor grow pattern, tumor differentiation degree, patient age and sex(all P>0.05).
  
  
  CONCLUSIONS
  Hypermethylation of hMLH1 gene promoter may be associated with the carcinogenesis stages and progression of human gastric cancer.
authors: Department of Gastrointestinal Surgery and Cancer Center, The Fourth Affiliated Hospital of China Medical University, Shenyang 110032, China. daidq63@163.com.
authors: Yue
authors: Y
authors: Teng
authors: Dongqiu
authors: D
authors: Dai
authors: Wenjing
authors: W
authors: Shen
authors: Hongbo
authors: H
authors: Liu
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D002471:Cell Transformation, Neoplastic; D002681:China; D019175:DNA Methylation; D018450:Disease Progression; D006801:Humans; D000070957:MutL Protein Homolog 1; D009687:Nuclear Proteins; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D013274:Stomach Neoplasms
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C501486:MLH1 protein, human; D009687:Nuclear Proteins; D000070957:MutL Protein Homolog 1