Objective To investigate the transcriptional activity of P53 in gastric cancer. Methods The activity of p53 in gastric cancer was investigatedby dual-luciferase reporter assay. The coding sequence of the p53 was amplified by reverse transcription-polymerase chain reaction(RT-PCR) and sequenced. The expression of P21WAF1/Cip1, Gadd45α and Mdm2 was detected by immunohistochemistry in 76 samples of gastric carcinoma, and their adjacent tissues were analyzed as control. Results Thep53 activity was higher in human normal cell lines than that of gastric cancer. Furthermore, the transcriptional activity of P53 was lowest in MKN28 cells in which p53 was mutated. The expression level of P21WAF1/Cip1 , Gadd45α and Mdm2 in the adjacent tissues was higher than that of cancer tissues (P<0.05), and there was a tendency of decline in the positive ratio with the poor differentiation of the carcinoma (P<0.05). In addition, a strong linear correlation was observed between P21WAF1/Cip1 , Gadd45α and Mdm2 (P<0.05). Conclusion Changes of P53 transcriptional activity play an important role in the development of gastric cancer. p53 mutation could affect its transcriptional activity. P21WAF1/Cip1 , Gadd45α and Mdm2 are a group of effecters that could reflect P53 transcriptional activity when detected together in cancer tissues.%目的 探讨P53蛋白转录调控活性在胃癌发生发展中的作用.方法 应用双荧光素酶报告基因测试(dual-luciferase reporter assay)检测人类胃癌细胞和正常细胞中p53转录调控活性,并通过逆转录-PCR对细胞中p53全长进行扩增,构建pMD18-T-p53重组质粒测序,检测p53突变对其活性的影响.应用免疫组织化学的方法 联合检测P21WAF1/Cip1,Gadd45α,Mdm2三种蛋白在76例胃癌及癌旁组织中表达水平,通过分析它们与肿瘤的临床病理特征及各个分子之间的相关性来间接反应P53在组织中的转录调控活性.结果 双荧光素酶报告基因显示p53转录调控活性在正常细胞中明显高于肿瘤细胞,在p53基因发生突变的细胞系MKN28中P53蛋白转录活性最低.免疫组化结果显示P21WAF1/Cip1,Gadd45α,Mdm2在癌旁组织中的表达明显高于肿瘤组织(P<0.05),且随着肿瘤TNM分期的增高有表达降低的趋势(P<0.05).P21WAF1/Cip1,Gadd45α,Mdm2之间的相关性分析结果显示3个分子在胃癌组织和癌旁组织中的表达呈正相关(P<0.05).结论 P53蛋白转录调控活性的变化在胃癌的发生发展中起着重要的作用,p53突变可以影响其转录调控活性.P21WAF1/Cip1,Gadd45α,Mdm2联合检测可以作为间接反映P53蛋白转录调控活性的效应分子.
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