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目的 微卫星是存在于人体基因组中的小片段核苷酸序列的串联式重复序列,有许多报道表明在遗传性结直肠癌中出现微卫星不稳定性。为了了解其在散发性结直肠癌发生发展中的作用,我们检测了50例散发性结直肠癌组织的微卫星不稳定性情况。方法 每例癌组织及邻近正常粘膜取出后进行DNA提取,选取BAT26微卫星位点设计引物进行PCR扩增,扩增产物在6％变性聚丙烯酰胺凝胶(含7M尿素)上电泳,根据正常粘膜及癌组织的电泳条带有无差异判定有无微卫星不稳定性。结果 在BAT26位点有13例(26％)出现异常,近端42.11％(8/19)高于远端16.13％(5/31)(P<0.05);分化程度好、中、差分别为8.33％、19.23％、58.33％,有明显相关性(P<0.01)。结论 散发性结直肠癌中微卫星不稳定性发生率较高,且与肿瘤部位及分化程度有明显相关性。
OBJECTIVE: Microsatellites are tandem repeats of small nucleotide sequences present in the human genome. Many reports indicate that microsatellite instability occurs in hereditary colorectal cancer. To understand its role in the development of sporadic colorectal cancer, we examined the microsatellite instability of sporadic colorectal cancer in 50 patients. Methods DNA extraction was performed after removal of cancerous tissue and adjacent normal mucosa in each case. BAT26 microsatellite loci were used to design primers for PCR amplification. The amplification products were electrophoresed on a 6% denaturing polyacrylamide gel (containing 7 M urea) according to normal conditions. The electrophoresis strips of mucosal and cancerous tissues had no difference to determine the presence or absence of microsatellite instability. Results Thirteen patients (26%) had abnormalities at BAT26, proximal 42.11% (8/19) was higher than distal 16.13% (5/31) (P<0.05); good differentiation, medium, and poor were 8.33%, 19.23%, 58.33%, there is significant correlation (P <0.01). Conclusion The incidence of microsatellite instability in sporadic colorectal cancer is high, and it has a significant correlation with tumor location and differentiation.