胃癌组织中DNA聚合酶β基因突变检测

Detection of DNA polymerase β mutation in human gastric cancer tissue

目的:了解胃癌组织中DNA聚合酶β(polβ)基因的突变情况。方法:利用RT-PCR、单链构象多态性(SSCP)和序列分析对38例胃癌组织及其相应癌旁正常组织标本polβ基因进行检测。利用DNASIS、OMIGA等软件分析测序数据,Chou&Fasman算法推测polβ氨基酸序列二级结构。结果:38例胃癌组织标本中SSCP异常9例(23.7%);而对应的癌旁正常组织均未见异常。polβ在低分化胃癌中的突变率达57.1%(8/14),而在中、高度分化胃癌中的突变率为4.2%(1/24),差异有统计学意义(P<0.05)。突变分别为196位A→G(28位Asn→Ser),268位A→G(52位Lys→Arg),790位A→T(226位Asp→Val)。其中196位A→G突变可导致polβ酶蛋白的二级结构明显改变。结果:胃癌组织中的polβ基因突变可能与胃癌的发生、发展有关。

Aim: To investigate the mutation of DNA polymerase β(polβ) in gastric cancer tissue.Methods: polβ genes from 38 cases of gastric cancer tissue and the corresponding adjacent cancer tissue were examined using RT-PCR,single-strand conformation polymorphism (SSCP) and sequence analysis, respectively.Sequence data were analyzed using DNASIS and OMIGA software,and the secondary structure of amino acid was assessed using Chou and Fasman method.Results: Obvious mutations were detected in 9 out of 38 cases of gastric cancer tissue(23.7%)and none abnormalities in corresponding adjacent gastric cancer tissue were found.The mutation rate of polβ gene was 57.1%(8/14)in low differentiated gastric cancer tissue,which was higher than that in moderate and high differentiated tissue (4.2%(1/24),P<0.05).Three point mutations were shown by sequence analysis as follows:A→G at 196 nt(Asn→Ser),A→G at 268 nt(Lys→Arg),A→T at 790 nt(Asp→Val),and mutation on the 196 nt could result in the obvious change of the secondary structure of DNA polβ protein.Conclusion: polβ gene mutations in human gastric cancer tissue may be associated with carcinogenesis and development of human gastric cancer.