胃癌患者6号染色体长臂遗传不稳定性

目的研究中国人胃癌6号染色体长臂微卫星不稳定性（microsatellite instability，MSI）和杂合性缺失（loss of heterozygosity，LOH）状况及与临床病理特征之间的联系。方法采用PCR-SSLP-银染方法对27例胃癌组织及其相应正常组织6号染色体长臂（6q）不同位置的4个位点进行MSI和LOH检测。结果27例信息个体中16例检测到一个或多个位点MSI，平均MSI频率59．2％；11例不具MSI的信息个体中7例存在1个或更多位点LOH，平均频率63．6％。MSI和LOH频发位点均为D6S434（6q16．3-q21）和D6S404（6q16．3-q23）。MSI和LOH在高分化胃癌和低分化胃癌各个时期均有发生．但高分化胃癌中高水平MSI（MSI-H）发生有增高趋势。结论MSI和LOH发生率与年龄、性别、组织分化程度、病理分期及发病部位等临床指标虽然无明显相关，但6q等位基因缺失关键区域与其它国家、地区相似，进一步证实6q上该区可能存在与胃癌相关的肿瘤抑制基因。

Inheritance Instability of Chromosome 6q in Patients with Gastric Cancer

Objective To investigate the possible correlation between the microsatellite DNA instability (MSI), loss of heterozygosity (LOH ) on the long arm of chromosome 6 (6q) and the clinicopathologic features in Chinese patients with gastric cancer. Methods PCR-SSLP-Silver Stain method was used to detect four loci MSI and LOH in gastric tumor and paired normal control tissues of twenty and seven cases. Results In our study, the positive of MSI at one or more loci were observed in 16 out of 27 informative individuals (59.2%).7 cases of 11 informative individuals without MSI were detected to happen the LOH at one or more loci (63.6%). And both MSI and LOH were frequently resulting at loci D6S434(6q16.3-q21) and D6S404 (6q16.3-q23.2). MSI and LOH occurred in both well-differentiated and poor_differentiated gastric cancers, with a slight tendency of high grade MSI (MSI-H) existing chiefly in well-differentiated gastric cancer. Conclusion The existence of MSI and/or LOH on 6q in 80% gastric carcinoma suggests that the genetic instability of 6q plays an important role in Chinese gastric cancer.The frequency of MSI and LOH has no significant relationship to clinicopathologic features such as age, gender, histological grade of differentiation and stages of tumor. The critical region of allelic deletion on 6q in Chinese gastric cancer is similar to those in other countries, and further confirms the presence of a putative tumor suppressor gene in this region.