Zhong Bi-Ling, Zong Yong-Sheng, Lin Su-Xia, Zhang Min, Liang Ying-Jie
Department of Pathology, Sun Yat-sen Medical College, Sun Yat-sen University, Guangzhou, Guangdong 510089, P. R. China.
Ai Zheng. 2006 Feb;25(2):136-42.
BACKGROUND & OBJECTIVE: The infiltrating neoplastic cells within early-stage nasopharyngeal carcinoma (NPC) are consistently infected with Epstein-Barr virus (EBV). The precursor lesions could often be found in paracancerous epithelium of early-stage NPC. This study was to investigate the role of EBV infection and the intrahost evolution of EBV genotype developed in nasopharyngeal carcinogenesis through detection of EBV harboring in precursor lesions.
EBV-encoded RNA (EBER) in 15 cases of early-stage NPC biopsy tissue was detected by nucleic acid in situ hybridization. EBV type and latent membrane protein 1 (LMP1) EBV strain in precursor lesions and carcinoma nests were detected by nested polymerase chain reaction (PCR). DNA sequencing of the representative PCR products of carboxyl-terminus of LMP1 gene was analyzed by using four-colored fluorescence terminator sequencing technique.
Most infiltrating carcinoma cells of all 15 cases of NPC showed EBER-positive. EBER-positive abnormal epithelial cells and/or infiltrating lymphocytes were found in 14 of 15 cases of precursor lesion. Single A-type EBV was detected in 9 of 11 available DNA samples of carcinoma nest and 9 of 10 available DNA samples of precursor lesion. The carboxyl-terminus of EBV LMP1 gene was detected in all 15 DNA samples of carcinoma nest, among which 14 were single 30-bp deleted LMP1 (del-LMP1) EBV infection and 1 was coinfection of wild-type LMP1 (wt-LMP1) EBV strain and del-LMP1 EBV strain. Among the 11 available DNA samples of precursor lesion suitable for carboxyl-terminus amplification, 5 were coinfection of wt-LMP1 and del-LMP1 EBV, 4 were single del-LMP1 EBV infection, 1 was single wt-LMP1 EBV infection, and 1 showed negative reaction. The DNA sequence of the carboxyl-terminus of wt-LMP1 gene was identical with that of B95-8 cells, while that of del-LMP1 gene had a 30-bp deletion (codon: 346-355) and 4 missense point mutations (codon: 334, 335, 338, and 366).
EBV infection in nasopharyngeal epithelial cells is a preinvasive event of carcinogenesis of NPC, and the intrahost evolution of EBV genotype would take place during nasopharyngeal carcinogenesis.
早期鼻咽癌（NPC）中的浸润性肿瘤细胞始终感染爱泼斯坦-巴尔病毒（EBV）。在早期NPC的癌旁上皮中常可发现其癌前病变。本研究旨在通过检测癌前病变中EBV的携带情况，探讨EBV感染及EBV基因型在鼻咽癌发生过程中的宿主内进化作用。
采用核酸原位杂交法检测15例早期NPC活检组织中的EBV编码RNA（EBER）。采用巢式聚合酶链反应（PCR）检测癌前病变和癌巢中的EBV类型及潜伏膜蛋白1（LMP1）EBV株。运用四色荧光终止测序技术分析LMP1基因羧基末端代表性PCR产物的DNA序列。
15例NPC的大多数浸润癌细胞呈EBER阳性。15例癌前病变中有14例发现EBER阳性的异常上皮细胞和/或浸润淋巴细胞。在11份癌巢可用DNA样本中的9份以及10份癌前病变可用DNA样本中的9份检测到单一A型EBV。在所有15份癌巢DNA样本中均检测到EBV LMP1基因的羧基末端，其中14份为单一30bp缺失的LMP1（del-LMP1）EBV感染，1份为野生型LMP1（wt-LMP1）EBV株与del-LMP1 EBV株的混合感染。在11份适合羧基末端扩增的癌前病变可用DNA样本中，5份为wt-LMP1与del-LMP1 EBV的混合感染，4份为单一del-LMP1 EBV感染，1份为单一wt-LMP1 EBV感染，1份呈阴性反应。wt-LMP1基因羧基末端的DNA序列与B95-8细胞的相同，而del-LMP1基因有一个30bp的缺失（密码子：346-355）和4个错义点突变（密码子：334、335、338和366）。
鼻咽上皮细胞中的EBV感染是NPC致癌的侵袭前事件，EBV基因型在鼻咽癌发生过程中会发生宿主内进化。
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