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背景与目的:先前的研究显示7号染色体长臂(7q)在原发性胃癌有高频缺失;位于7q31的D7S486是7q上最高频的杂合性缺失(lossofheterozygosity,LOH)位点,且该位点的LOH频率与肿瘤的淋巴结转移显著相关;推测D7S486位点附近可能存在胃癌相关的抑癌基因(tumorsuppressorgene,TSG)。为能在更小的区域内找寻胃癌相关的TSGs,本研究通过检测原发性胃癌在7q31区域内微卫星标记位点的LOH情况,确定胃癌的最小共同缺失区域,并分析它们在胃癌发病中的可能作用。方法:以D7S486位点为中心,在位于其上下的7q31区域内选取平均遗传距离约0.5厘摩(centimorgan,cM)的12个微卫星标记。显微切割78例原发性胃癌和相应的正常胃粘膜组织,分别提取DNA;进行多重PCR扩增,聚丙烯酰胺凝胶电泳分离PCR产物,以GeneScan、Genotyper软件分析各微卫星位点的LOH情况。根据LOH结果作图,确定胃癌在7q31内的最小共同缺失区域,并与临床病理指标联系,分析区域缺失在胃癌发病中的可能作用。结果:12个微卫星标记位点均可在原发性胃癌中出现LOH,总的LOH频率为41.7%(40/72)。LOH的最高频位点是D7S486(位于7q31.2),为30.4.%(17/56);次高频位点是D7S650(位于7q31.3),为21.1%(8/38)。原发性胃癌在7q31内有两个最小共同缺失区域,分别为D7S2543～D7S486和D7S480～D7S650(长度均约为90kb)。D7S2543～D7S486区域缺失的频率与胃癌患者的临床分期和淋巴结转移显著相关(P=0.01和P=0.03);D7S480～D7S650区域缺失的频率与胃癌患者的临床分期显著相关(P=0.03),且该区域缺失仅出现于临床Ⅲ/Ⅳ期、T3/T4期或淋巴结转移的患者。结论:原发性胃癌在染色体7q31上存在两个最小共同缺失区域,分别为D7S2543～D7S486和D7S480～D7S650;在这两个区域内可能存在胃癌发展密切相关的抑癌基因。
BACKGROUND AND AIM: Previous studies showed that the long arm of chromosome 7 (7q) is highly frequently deleted in primary gastric cancer; D7S486 at 7q31 is the highest frequency loss of heterozygosity (LOH) site on 7q and The frequency of LOH in this locus was significantly correlated with the lymph node metastasis of the tumor. It is speculated that gastric cancer-associated tumor suppressor genes (TSG) may exist near the D7S486 locus. In order to search for gastric cancer-related TSGs in a smaller area, this study determined the minimum co-deletion region of gastric cancer by detecting the LOH of microsatellite markers in 7q31 region of primary gastric cancer and analyzed their role in the pathogenesis of gastric cancer The possible role. Methods: With the D7S486 locus as the center, 12 microsatellite markers with an average genetic distance of about 0.5 centimeter (cM) were selected in the 7q31 region located above and below them. 78 cases of primary gastric cancer and corresponding normal gastric mucosa were microdissected and DNA was extracted separately. Multiplex PCR amplification and PCR products were separated by polyacrylamide gel electrophoresis. The LOH of each microsatellite locus was analyzed by GeneScan and Genotyper software Happening. According to the results of LOH, the smallest common deletion region of gastric cancer in 7q31 was determined and correlated with clinicopathologic parameters to analyze the possible role of regional deletion in the pathogenesis of gastric cancer. RESULTS: All 12 microsatellite loci showed LOH in primary gastric cancer, with a total LOH frequency of 41.7% (40/72). The highest frequency of LOH was D7S486 (at 7q31.2), which was 30.4% (17/56) and the second was D7S650 (at 7q31.3), which was 21.1% (8/38). There are two regions of minimal common deletion in 7q31, which are D7S2543 ~ D7S486 and D7S480 ~ D7S650 (all about 90kb in length). The frequency of D7S2543 ~ D7S486 region deletion was significantly correlated with the clinical stage and lymph node metastasis (P = 0.01 and P = 0.03) in gastric cancer patients. The frequency of D7S480 ~ D7S650 region deletion was significantly correlated with the clinical stage of gastric cancer (P = 0.03) This region is missing only in patients with stage III / IV, T3 / T4 or lymph node metastases. CONCLUSIONS: There are two minimal common deletion regions on chromosome 7q31 in primary gastric cancer, which are D7S2543 ~ D7S486 and D7S480 ~ D7S650, respectively. There may exist tumor suppressor genes closely associated with the development of gastric cancer in these two regions.