The relation of microsatellite instability to expression of hTERT in human gastric carcinoma.

OBJECTIVE: To investigate the role of microsatellite instability (MSI) in the pathogenesis of gastric carcinoma and its relationship with the expression of hTERT gene. METHODS: 75 cases of gastric carcinoma and paired normal control tissues were included in this study. MSI of BAT-25, BAT-26, D5S346, D17S250 and D2S1235 were detected by PCR, native polyacrylamide gel electrophoresis, and silver staining while the expression of hTERT was localized by immunohistochemistry at the same time. RESULTS: MSI positive rates of BAT-25, BAT-26, D5S346, D17S250 and D2S123 were 14.7%, 12.00%, 26.67%, 16% and 21.3%. MSI was obviously related with lymph node metastasis and pathologic stages respectively (P 0.05). hTERT was not expressed in normal gastric mucosa, but in intestinal metaplasia, dysplasia, and gastric carcinoma. The positive rate of hTERT was 76% (57/75) in 75 cases of gastric carcinoma tissues. The expression of hTERT was obviously related to histological type (P 0.05). The positive rate was higher in poorly differentiated cases than in moderately and well differentiated cases (P<0.05). MSI accounted for 28.1% of 57 hTERT positive cases while MSI accounted for 72.2% in 18 hTERT negative cases. Spearman rank correlation analysis showed that MSI was negatively related to hTERT expression (r=0.387, P=0.001). CONCLUSION: MSI may play an important role in the pathogenesis and progression of gastric carcinoma by affecting the expression of TERT gene.