卵巢癌PTEN基因失活机制的探讨  

Research on the mechanisms of PTEN gene inactivation in ovarian cancer

作　　者：吕庆杰[1] 赵晓东[1] 宋继谒[2] 李晓晗[1] 马颖[1] 孟辉[1] 姜卫国[1] 

机构地区：[1]中国医科大学第二临床学院,沈阳110004 [2]中国医科大学第二临床学院病理学教研室,沈阳110004

出　　处：《中华病理学杂志》2005年第5期266-269,共4页Chinese Journal of Pathology

摘　　要：目的　旨在从DNA、mRNA及蛋白水平,探讨卵巢癌PTEN基因的失活机制。方法　48例卵巢癌标本,应用位于染色体10q23 3的4个多态性标记(D10s541、D10s583、D10s1687和D10s2491),采用聚合酶链反应(PCR)及杂合性缺失分析法,检测了PTEN杂合性缺失(LOH);采用聚合酶链反应单链构象多态性分析法(PCR SSCP)检测了PTEN第5、第6、第7和第8外显子的突变;采用逆转录(RT) PCR及免疫组织化学技术检测了PTENmRNA及蛋白的表达。结果　39 6%(19 /48)的卵巢癌存在PTEN基因的LOH, PTEN突变率仅为4 2% (2 /48),PTENmRNA表达缺失率为18 8% (9 /48),蛋白表达缺失率达27 1% (13 /48)。PTEN蛋白表达缺失的病例,LOH的发生率69 2% (9 /13)高于表达阳性者的28 6% (10 /35),差异有统计学意义(P<0 05 )。13例PTEN蛋白表达缺失的病例中,仅有2例( 15 4% )同时有突变和LOH,即存在双等位基因的结构异常; 7例(53 8% )有LOH,其中5例PTENmRNA表达缺失,另2例表达正常; 4例( 30 8% )既无突变也无LOH,其中2例PTENmRNA表达缺失,另2例表达正常。结论　PTEN基因失活在卵巢癌的发病中可能起一定的作用,其失活可能存在多种机制,蛋白表达缺失可能是重要的失活机制。Objective To investigate the mechanisms of PTEN gene inactivation starting from DNA, mRNA and protein levels in ovarian cancers.Methods Tumor tissue samples were obtained from 48 patients with epithelial ovarian cancers. Using four polymorphic markers (D10s541, D10s583, D10s1687 and D10s2491) within and flanking the PTEN gene located in chromosome 10q 23.3, polymerase chain reaction (PCR) and loss of heterozygosity (LOH) were introduced to examine LOH of PTEN gene; PCR-single strand conformation polymorphism (PCR-SSCP) was introduced to examine mutations of the fifth, sixth, seventh, and eighth exons of PTEN. Reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry (SP method) were applied to detect PTEN mRNA and PTEN protein expressions, respectively.Results LOH of PTEN gene was observed in 19 of 48 (39.6%) ovarian cancers. PTEN mutations were found only in 2 (4.2%) of the cases. Absence of PTEN mRNA expression was 18.8% (9 of 48). Immunostaining of 48 cancer samples revealed that 13 (27.1%) were PTEN immunostain negative. Of these 13 samples, only 2 (15.4%) had structural, biallelic inactivation by intragenic PTEN mutations and loss of the remaining wild-type allele; 7 (53.8%) showed evidence of LOH, 5 of these 7 samples showed deletion of PTEN mRNA expression, another 2 samples showed positive expression of PTEN mRNA; 4 (30.8%) tumors had neither PTEN gene mutation nor LOH but exhibited no PTEN protein expression, 2 of these 4 cases showed deletion of PTEN mRNA expression, another 2 showed positive expression of PTEN mRNA. For the cases of PTEN protein absent staining, the rate of LOH was 69.2% (9 of 13), higher than 28.6% (10 of 35) for the positive staining (P<0.05).Conclusions PTEN gene inactivation may contribute to epithelial ovarian carcinogenesis. There may be several mechanisms of PTEN gene inactivation in ovarian cancers. Protein expression deletions may be a significant mechanism.

关 键 词：卵巢癌 PTEN基因 失活机制 蛋白表达 肿瘤 

分 类 号：R737.31[医药卫生—肿瘤]