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目的 研究散发性结直肠癌5号染色体的杂合性缺失,寻找新的结直肠癌抑癌基因.方法 取83例结直肠癌患者的肿瘤和正常组织,先后应用分布于5号染色体上的16对微卫星DNA标记和5p15区D5S416附近的6对微卫星DNA标记进行聚合酶链反应(PCR),PCR产物在自动荧光测序仪进行电泳3h,以GeneScan3.1和Genotyper2.1软件进行基因分型.结果 经5号染色体上的16对微卫星DNA标记的杂合性缺失分析,发现散发性结直肠癌5号染色体上有2个明显的高频杂合性缺失区域,即染色体短臂上的D5S416位点和染色体长臂上的D5S428～D5S410区.进一步对5p15区的精细定位,界定了1个遗传距离为1 cM大小、跨越D5S416位点的杂合性缺失区,该区的位点大致顺序是pter-D5S630-D5S1987-D5S1991-D5S1954-D5S1963-D5S416-D5S2114-D5S486.本组54例有效标本的杂合性缺失率达48.2%.结论 散发性结直肠癌在5号染色体短臂存在1个杂合性缺失区域,即5p15.2-15.3,该区很可能存在1个或多个与结直肠癌相关的新的抑癌基因.

Objective To refine the loss of heterozygosity (LOH) on chromosome 5p15 and screen new tumor suppressor gene (s) in colorectal tumorigenesis. Methods Samples of colorectal cancer and normal tissue of 83 cases were collected in this study. Sixteen polymorphic microsatellite markers were analyzed on chromosome 5 and another 6 markers on chromosome 5p15 by PCR. PCR products were electrophoresed on an ABI 377 DNA sequencer. Genescan 3.1 and Genotype 2.1 software were used for LOH scanning and analysis. Results Two distinct regions of frequent allelic deletions at D5S416 on 5p15and DSS428-DSS410 on 5q were detected. Another 6 polymorphic microsatellite markers were applied to 5p15 and the minimal region of frequrent loss of heterozygosity was established on 5p15 spanning the D5S416locus. Conclusion A critical and precise location of 5p deletions, 5p15.2-5p15.3, has been detected, which may contain one or more unknown tumor suppressor gene(s) related to colorectal cancer.