一个与化学因素致鼻咽癌相关的硝基还原酶基因的克隆与鉴定(英文)

Molecular Cloning and Characterization of a Novel Nitroreductase Gene,NOR_1,Possibly Involved in Chemical Carcinogenesis of NPC

在运用cDNAmicroarray分析鼻咽癌细胞系CNE1与正常鼻咽上皮细胞差异表达基因的基础上 ,发现ESTW 95 442在细胞系CNE1中存在明显表达下调 .随后采用生物信息学的方法克隆出了该EST所代表的硝基还原酶基因NOR1(GenBank登录号为AF4 6 2 348) .Northern印迹分析表明 ,该基因在脑、心脏、肺等正常组织中均有 2个转录产物 (1.6kb ,1.2kb) .RT PCR分析显示 ,NOR1基因在鼻咽癌活检组织中也存在表达下调 .但酶活性测定实验表明 ,它在鼻咽癌细胞系CNE1中的活性比正常鼻咽上皮细胞高 .通过基因转染实验发现NOR1基因具有与细菌硝基还原酶NTR相似的功能 ,能够将单功能烷基化试剂 2 硝基苯氮丙啶类化合物CB195 4的第 4位硝基还原成亚硝基从而生成细胞毒性物质 .研究结果表明 。

The expression of ESTW95442 is down regulated in nasopharyngeal carcinoma cell line CNE 1, in comparison with normal nasopharyngeal epithelial cell, which was confirmed by cDNA microarray analysis. Subsequently, the novel gene, NOR 1 (GenBank Accession No.AF462348), corresponding to ESTW95442 was cloned by cDNA cloning and bioinformatics analysis. Northern blot analysis showed that NOR 1 gene had two transcripts (1.6 kb, 1.2 kb) and expressed in almost normal human tissues. RT PCR analysis showed that the expression of NOR 1 was also down regulated in nasopharyngeal carcinoma (NPC) biopsies. However, NOR 1 had high enzyme activity in CNE 1 compared with normal nasopharyngeal epithelial cell. The conditioned media of CNE 1 cells transfected with full length NOR 1 cDNA showed that the NOR 1 had the similar activity to the bacterial nitroreductase NTR, which could convert monofunction alalkylating agent, CB1954 ([5 aziridin 1 yl] 2,4 dinitrobenzamide) into a toxic form by reducing the 4 nitro group of CB1954. The findings suggest that the NOR 1 gene may play an important role in the formation of chemical carcinogen and carcinogenesis of NPC by its nitrosation function and high enzyme activity.