EB病毒相关胃癌细胞凋亡与Bcl-2的表达

Apoptosis and expression of Bcl-2 in Epstein-Barr virus-associated gastric carcinoma

目的:探讨EBV相关胃癌(EBV associated gastric carcinoma, EBVaGc)病毒基因表达、Bcl-2蛋白表达与细胞凋亡的相互关系,明确其在EBVaGC发生发展中的作用. 方法:选取EBVaGC和相应癌旁组织13例,与之匹配的EBVnGC 45例,采用TUNEL法及免疫组化技术检测其细胞凋亡指数(AI)和bcl-2蛋白的表达;RT-PCR-Southern杂交技术检测EBV相关基因表达. 结果:EBVaGC、EBVnGC及EBVaGC癌旁组织中AI分别为0.97±0.41,2.03±0.60和3.25±0.46,统计学分析表明: EBVaGC和EBVnGC以及EBVaGC癌组织和相应癌旁组织细胞凋亡指数均有显著性差异(t=5.9795,P=0;t=13.2229, P=0).EBVaGC组和EBVnGC组Bcl-2阳性率分别为53.8% 和48.9%,两组间无显著性差异(X2=0.0991,P=0.7529). EBVaGC 13例EBNA1 mRNA均阳性,而EBNA2和LMP1 mRNA均阴性;EBV早期基因BARF1表达阳性6例,BHRF1 表达阳性2例. 结论:EBVaGC癌组织Bcl-2表达与EBV感染无明显相关性,EBV感染抑制细胞凋亡不是上调Bcl-2表达而实现, EBV早期基因BARF1和BHRF1可通过抑制细胞凋亡和细胞转化作用参与EBVaGC的发生.

AIM: To understand the relationship between Epstein-Barr virus related genes expression, Bcl-2 expression and apoptosis in EBV-associated gastric carcinoma (EBVaGC) and their roles in the oncogenesis and development of gastric carcinoma. METHODS: The apoptotic index (AI) and the expression of Bcl-2 protein were detected by terminal deoxynucleotidy1 transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL) and immunohistochemistry, respectively, in 13 cases of EBVaGC and 45 EBVnGC. The expression of EBV related genes was tested by RT-PCR and Southern blotting. RESULTS: AI of EBVaGC, EBVnGC and the corresponding adjacent tissues of EBVaGC were 0.97±0.41, 2.03±0.60 and 3.25±0.46, respectively. AI of EBVaGC was significantly lower than that of EBVnGC (t=5.9 795, P=0) and corresponding adjacent tissues of EBVaGC (t=13.2 229, P=0). The expression of Bcl-2 protein was detectded in 7 of 13 (53.8%) EBVaGC and in 22 of 45 (48.9%) EBVnGC. The difference between the two groups was not significant (X2=0.0 991, P= 0.7 529). EBNA1 mRNA was detected in all of 13 EBVaGC, while both EBNA2 and LMP1 mRNA were not detected in the cases. Of the 13 EBV-positive samples, 6 exhibited BARF1 transcripts and 2 exhibited BHRF1 transcripts. CONCLUSION: Bcl-2 expression does not correlate with the presence of EBV in EBVaGC. EBV infection can inhibit cell apoptosis not by Bcl-2 expression. Early genes BARF1 and BHRF1 might play an important role in the development and progression of gastric carcinomas by the mechanisms of immortalizing epithelial cells and inhibiting cell apoptosis.