EB病毒相关胃癌组织中病毒基因的表达

Expression of Epstein Barr Virus Genes in EBV-Associated Gastric Carcinoma

背景与目的EB病毒(Epstein-Barrvirus,EBV)与多种恶性肿瘤的发生有关,在鼻咽癌及淋巴瘤等组织中EBV的存在形式和表达已有报道,研究表明不同肿瘤组织中EBV的存在形式和表达不同,在胃癌组织中EBV某些基因尤其是裂解性基因的表达情况报道较少。为明确胃癌组织中EBV潜伏性基因和裂解性基因的表达情况,本研究从mRNA水平检测胃癌组织中EBV潜伏感染和裂解感染相关基因的表达,从分子水平探讨EBV编码基因与胃癌发生发展的关系。方法应用PCR-Southern杂交检测185例胃癌及其相应癌旁组织中特异性EBVDNA片段,进一步用原位杂交(ISH)技术检测PCR阳性标本EBV编码小RNA1(EBER1)的表达,癌细胞EBER1阳性者确定为EBV相关胃癌(EBV-associatedgastriccarcinoma,EBVaGC)。采用RT-PCR和Southern杂交技术检测EBVaGCs组织中EBV核抗原(EBNAs)基因转录启动子(Qp、Cp和Wp)、潜伏性基因(EBNA1、EBNA2基因,潜伏膜蛋白LMP1、LMP2A和LMP2B基因)和裂解性基因(即刻早期基因BZLF1和BRLF1,早期基因BARF1和BHRF1,晚期基因BcLF1和BLLF1)的表达。结果185例胃癌标本EBV阳性率为7.03%(13/185),癌旁组织均为阴性。13例EBVaGCs组织中均检测到启动子QpmRNA,而Wp和CpmRNA则为阴性。潜伏性基因中EBNA1mRNA均阳性(13/13),而EBNA2。

BACKGROUND & OBJECTIVE: Epstein Barr virus (EBV) is associated with the development of many malignant tumors. The forms of EBV and the expression of EBV genes in Burkitts lymphoma and nasopharyngeal carcinoma (NPC) have been reported. These studies showed that the forms of EBV and the expression of EBV genes are various in different types of malignancies. However, there were only a few reports about the expression of EBV genes, especially the lytic genes, in gastric carcinoma tissues. This study was to determine the expression of EBV latent and lytic infection genes in gastric carcinoma at the transcriptional level by RT PCR and Southern hybridization,and investigate the relationship between EBV encoded genes and the tumorigenesis of gastric carcinoma at the molecular level. METHODS: One hundred and eighty five gastric carcinoma and corresponding para carcinoma tissues were tested for EBV genome by polymerase chain reaction (PCR) Southern analysis. EBV encoded small RNA 1 (EBER1) of the PCR positive specimens was determined by in situ hybridization (ISH). Gastric carcinoma with positive EBER1 signals was confirmed EBV associated gastric carcinoma (EBVaGC). RT PCR and Southern hybridization were used to determine the expression of nuclear antigen (EBNA) promoters (Qp, Wp and Cp), EBNA 1 and 2,latent membrane protein (LMP) 1, 2A, and 2B and lytic genes (immediate early genes BZLF1 and BRLF1, early genes BARF1 and BHRF1, late genes BcLF1 and BLLF1) in EBVaGCs. RESULTS: There were 13 EBV positive samples in gastric carcinomas (7.03%), but no EBV positive sample in corresponding para carcinomas. The transcripts of Qp were detected in all of the 13 EBVaGCs tissues, while both Wp and Cp were silent. All of the 13 cases expressed EBNA1 mRNA, but no EBNA2, LMP1, and LMP2B mRNA. LMP2A mRNA was detected in 5 of the 13 cases. Of the 13 EBVaGCs, 7 exhibited BcLF1 transcript and 2 exhibited BHRF1 transcript. The transcripts of BZLF1 were detected in 6 cases, and those of BARF1 also in 6 cases. No BLLF1 and BRLF mRNA were detected in the 13 EBVaGCs. CONCLUSIONS: The latent pattern of EBV in EBVaGCs corresponds to the latency I or unique latency I/II, intermediate between the latency I and II. Part of lytic infection genes are expressed in EBVaGCs tissues. BARF1 and BHRF1 genes express in part of gastric carcinomas and their roles in gastric tumorigenesis need to be further studied.