胃癌及癌前病变中微卫星不稳定性的变化

Changes in microsatellite instability in gastric cancer and precancerous lesions

目的：探讨胃癌及癌前病变中微卫星不稳定（MSI）的变化．方法：饱和氯化钠法提取组织DNA，PCR-SSCP变性聚丙烯酰胺凝胶电泳检测MSI，根据规定标准来判定microsatellite stable（MSS），low frequency MSI（MSI-L）和high-frequency MSI（MSI-H），计算总MSI率．结果：MSI在萎缩性胃炎，肠上皮化生，不典型增生，早期胃癌和进展期胃癌中检出率分别为13．3％、16．7％、23．3％、30％和40％，三种癌前期病变和早期胃癌之间有显著差异（χ^2值分别为4．364、2．522、3．089，P〈0．05），早期胃癌与进展期胃癌没有显著差异（χ^2值为0．071 P〉0．05），高分化腺癌中MSI的阳性率明显高于低分化腺癌（χ^2值为4．022，P〈0．05）．结论：MSI是胃癌发生中的早期分子标志，其阳性的胃癌恶性程度相对较低．

AIM： To investigate the changes in microsatellite instability （MSI） in gastric cancer and pre cancerous lesions. METHODS： DNA was extracted by the method of saturated sodium chloride. MSI was detected by PCR-SSCP denaturing PAGE and silver staining, microsateUite stability （MSS）, low-frequency MSI （MSI-L） and high-frequency MSI （MSI-H） were evaluated following the international MSI workshop-recommended standard. RESULTS： According to the international MSI workshop recommended standard, the total positive rate of MSI was 13.3 % for atrophic gastritis, 16.7% for intestinal metaplasia, 23.3% for atypical hyperplasia, 30% for early stage gastric cancer, and 40% for advanced stage gastric cancer. There were differences between three kinds of precancerous lesions and gastric cancer （χ^2 was 4.364, 2.522 and 3.089, respectively, P 〈 0.05）. There was no difference between early and advanced stage gastric cancer （χ^2 was 0.071）. The positive rate of MSI in well-differentiated adenocarcinoma was higher than that in poorly differentiated adenocarcinoma （χ^2 was 4.022, P 〈 0.05）. CONCLUSION： MSI is an early molecular marker in the pathogenesis of gastric cancer. The malignant degree of MSI positive gastric cancer may be low.