溃疡性结肠炎及伴发癌的p53改变和微卫星不稳定性  

Alterations of p53 gene and microsatellite instability in ulcerative colitis and ulcerative colitis-associated colorectal cancer

作　　者：李君[1] 来茂德[1] 黄琼[1] 

机构地区：[1]浙江大学医学院病理学和病理生理学系,环境基因组学研究中心,浙江杭州310031

出　　处：《浙江大学学报（医学版）》2004年第2期108-114,共7页Journal of Zhejiang University(Medical Sciences)

基　　金：国家自然科学基金 (39770 2 97)资助项目

摘　　要：目的 :探讨溃疡性结肠炎和不典型增生、癌变组织的 p5 3基因改变和微卫星不稳定性状况。方法 :采用SP法检测 2 1例 70个手术切除的溃疡性结肠炎标本和 2 5例正常人的 P5 3蛋白表达 ;人工微切割 - PCR- SSCP/HA-克隆测序技术检测溃疡性结肠炎标本 p5 3基因第 5 - 8外显子的点突变 ;SSLP-测序技术检测 10个微卫星位点的改变情况。结果 :P5 3蛋白免疫组化发现 2 5例正常人全部阴性 ;溃疡性结肠炎患者 4例阳性 ,其中炎症性、低度不典型增生 (LGD)、高度不典型增生 (HGD)与癌变阳性标本分别为 0 /5例、1/7例、2 /7例和 1/2例。SSCP/HA、SSLP结果各有 2例阳性 ,其中 1例癌变病例癌组织 p5 3基因第 6外显子及 Bat2 6微卫星位点均阳性 ,其 LGD区 Bat2 6也阳性 ;1例 LGD病例 Bat2 6位点阳性 ;另 1例 HGD病例 p5 3基因第 8外显子阳性 ,后者经测序证实发生了移码突变。 2 1例标本在 TGFβRII(A) 10 、IGFIIR(G) 8、IGFIIR(CT) 5、TGFβRII(GT) 3 、BAX(G) 8、h MSH3(A) 8、h MSH6(C) 8、TCF4 (A) 9和 DPC4 (CA) 179个微卫星位点都阴性。结论 :溃疡性结肠炎和癌变黏膜的早期就存在 P5 3蛋白的过表达和微卫星不稳定性 ,前者部分是基因突变的结果。Objective: To study the expression of p53 protein, incidence of p53 gene mutation and microsatellite instability in ulcerative colitis, dysplasia of colonic mucosa and ulcerative colitis-associated colorectal cancer. Me-thods: P53 protein expression was detected by immunhistochemistry in 70 specimens from 21 cases of ulcerative colitis and 25 colonic mucosa specimens from normal subjects. The specimens of ulcerative colitis were examined for the mutation in exon 5, 6, 7, 8 of p53 gene with microdissection- PCR- SSCP/HA-clone-sequenceing technique and the alterations in 10 microsatellite loci with microdissection-PCR-SSLP-clone-sequenceing technique. Results: None of 25 normal specimens was p53-positive immunohistochemically, while 4/21 of ulcerative colitis specimens were p53-positive. P53-positive rate in inflammatory mucosa of ulcerative colitis specimens was 0/5, while that was 1/7, 2/7 and 1/2 in low-grade displasia (LGD), high-grade displasia (HGD) and carcinoma, respectively. The abnormal exons were detected by SSCP and confirmed by sequencing in 2 out of 21 cases: one was exon 6 in a case with carcinoma and the other was exon 8 in a HGD case; both had positive P53 expression. Two cases showed positive in Bat26 locus by SSLP: one was a LGD case, the other was a case of carcinoma, who also had abnormal exon 6 of p53 gene. Other 9 microsatellite loci, (TGFβRII(A) 10, IGFIIR(G) 8, IGFIIR(CT) 5, TGFβRII(GT) 3, BAX(G) 8, hMSH3(A) 8, hMSH6(C) 8, TCF4(A) 9 and DPC4 (CA) 17) were showed negative in all cases. Conclusion: P53 gene mutations and microsatellite instability may be one of the mechanisms for higher risk of carcinogenesis in ulcerative colitis.

关 键 词：溃疡性结肠炎 P53基因 微卫星不稳定性 DNA序列分析 

分 类 号：R574.62[医药卫生—消化系统]