人胃癌细胞系中p53抑癌基因变异的检测及其序列分析

ｐ５３抑癌基因由于点突变，缺失或易位等方式而丧失活性是多种肿瘤发生发展的重要机理之一。本文应用聚合酶链式反应─—单链构象多态性分析（ＰＣＲ－ＳＳＣＰ）方法，对四种人胃癌细胞系ＭＧＣ８０３，ＢＧＣ８２３，ＧＣ７９０１和ＰＡＭＣ－８２中ｐ５３基因的第５、６、７、８四个外显子进行检测，结果发现，ＰＡＭＣ－８２的第５和第８外显子，ＧＣ７９０１的第６外显子存在突变。ＰＣＲ－直接测序证明，它们分别在１７４位、２８０位、２０４位密码子发生缺失Ｇ，ＧＣ→ＣＧ，ＡＴ→ＣＧ转变，因而可使其编码的ｐ５３蛋白分别发生移码突变，Ａｒｇ→Ｔｈｒ，Ｇｌｕ→Ａｌａ，而丧失肿瘤抑制功能。实验结果表明，ｐ５３基因在胃癌发生发展过程中，尤其是较晚阶段具有重要作用。

p53 Gene Mutation in Chinese Gastric Carcinoma Cell Lines

Mutation of p53 gene is believed to be closely related to the tumorigenesis and development of cancer. Studies on p53 gene in Chinese gastric carcinoma are rare now. Here we reported that polymerase chain reaction (PCR)-single strand conformation polymorphism (SSCP) was used to detect the mutation of p53 gene within its 5,6,7 and 8 exons of Chinese gastric carcinoma cell line MGC803,BGC823,GC7901 and PAMC-82. The results showed that aberrations happened at of the 5th and 8th exon in PAMC-82 and the 6th exon in GC7901. The deletion of G base at codon 174 and transversion of GC→CG at codon 280,AT→CG at codon 204 were detected by PCR-directed sequencing. This may result in the frameshift mutation, Arg→Thr,Glu→Ala of expressed p53 protein. This may make contribution to the cancer development of PAMC-82which has been derived from metastasis of gastric carcinoma from stomach to the tongue. It suggests that mutation of p53 gene may play an important role in later stage of tumorigenesis and cancer metastasis.