| Cell malignant transformation is a very complicated process and might be influenced by multiple factors. In addition to Epstein-Barr virus (EBV), the development of nasopharyngeal carcinoma (NPC) is also associated with genetic, environmental, dietary factors, etc. With studies going on, the role of EBV in nasopharyngeal carcinogenesis has stepped into the focus of attention.The EBV infection spectrum is very narrow. It can only infect a few kinds of new world primates and human being. It mainly infects two target tissues in vivo: B lymphocytes and stratified squamous epithelium, and is a causative agent for tumors such as Burkirt lymphoma and B lymphoproliferative disease arising from B lymphocytes and NPC originating from nasopharyngeal epithelial cells. The mechanism of EBV entry into B-lymphocytes has been well known. B-lymphocytes express EBV receptor CR2 (complement receptor type 2) on its membrane surface. CR2 is the receptor of C3d. Since the molecular conformation of major EBV outer membrane glycoprotein, gp350/220, is highly homologous to C3d, so EBV can infect B-lymphocytes through its binding to CR2.The mechanisms of EBV entry into epithelial cells are still poorly understood. Studies showed that EBV might enter epithelial cells through the following four pathways: (1) by EBV receptor CR2 expressing on the surface of epithelial cell membranes; (2) as a part of immune complexes, mediated by the uptake of polymeric immunoglobulin A and pIgA receptoracross mucosal epithelium; ( 3 ) by direct cell-to-cell contact of apical cell membranes with EBV-infected lymphocytes or by the fusion to mucosal cell membranes; (4) by entering epithelial cells with the help of co-factors/co-receptors, or by translating EBV into a kind of pseudo-type to which epithelial cells are susceptible .While studying the relationship between EBV and NPC, the most frequent problem met is EBV can't infect normal human epithelial cells in vitro, nor can it transform epithelial cells to establish a representative NPC cell model. Seeking appropriate cell and animal models is always the pursuing target for investigators. We took an attempt in this paper. With the help of transgenic technology, we try to introduce the gene of EBV -related receptors into mouse nasopharyngeal epithelial cells, hoping to establish a kind of mouse model which could be infected by EBV naturally, and lay the foundation of studying the nasopharyngeal carcinogenisis related to EBV in this animal model.This paper took the following studies:1, The construction of transgenic vector. ED-L2 promoter was obtained by polymerase chain reaction (PCR) method, then was used to construct epithelium-specific eukaryotic expression vectors pEDL2-hCR2/pEDL2-pIgR respectively. By restriction endonuclease digestion analysis and sequence verification, the positive vectors containing target genes inserted in sense orientation were obtained.2, Gene transfection in vitro and analysis of transgenic vectors. The identified pEDL2-hCR2/pEDL2-pIgR vectors were transferred into human immortalized keratinocyte cell line HaCaT and transformed epithelial cell line TMNE derived from mouse nasopharynx respectively by lipofectAMINE. Stable CR2/pIgR-expressing transfected cells were cloned. Reverse transcriptase PCR was used to detect the expression of both target genes at the level of messenger RNA (mRNA) and so did immunohistochemical method to test the expression of target proteins. Results showed both targetgenes could express correctly in host cells. These two identified vectorswere also transferred into human fibroblasts WI-38, human colorectal cancer cell line LOVO and mouse fibroblasts NIH3T3 for 72 hours. Both target genes couldn't express in WI-38 and NIH3T3 cells. No significantly different expression at mRNA level of target genes was observed in LOVO cells treated with CR2/pIgR or vector and blank control.3, EBV Infection of stably transfected cells in vitro. Stable CR2/pIgR expression cell clones of HaCaT and...
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