中文摘要：

背景与目的：EB病毒潜伏性膜蛋白1（1atentmembraneproteinl，LMP1）是病毒基因组编码的致瘤蛋白。本研究拟探讨LMP1在细胞转化和致瘤过程中的作用机制。方法：采用基因重组方法构建LMP1和显性负突变IgBa逆转录病毒质粒pLNSX—LMP1和pBabe-IκBα，分别与含有转录因子NF-κB启动子的荧光素酶表达质粒共转染293细胞。单光子检测仪测定LMP1对NF-κB的活化作用及IgBa对NF-κB的抑制作用；同时将2种重组病毒载体分别导入PA317细胞包装。获取2种逆转录病毒（retrovirus，RV），单独（RV—LMPl）或先后（先RV—LMP1后RV—IκBα）感染体外培养的Ratl细胞，检测转导细胞的集落形成能力及裸鼠成瘤能力。结果：当pBabe-IκBα与pLNSX-LMP1以1：1共转染，IκBα能使LMP1活化NF-κB的作用降低75％；当以3：1共转染，LMP1的活化作用几乎全部被抑制。IκBα能明显抑制RV—LMP1感染细胞的恶性表型：平皿克隆形成数从368±7和287±17分别降至59±6和8±2（n=3，P〈0．001）；软琼脂集落形成数从477±13和347±10分别降至61±15和95±7（n=3，P〈0．001）；裸鼠成瘤能力显著降低，瘤体积自（1．61±0．23）cm^3降至（0．20±0．08）cm^3（n=5，P〈0．001）。结论：EB病毒LMP1促Ratl细胞恶性转化作用主要依赖NF-κB的活化。

英文摘要：

BACKGROUND ＆ OBJECTIVE： Epstein-Barr virus （EBV） latent membrane protein 1 （LMP1） is an oncoprotein coded by EBV genome. This study was to investigate the effects of EBV LMP1 on transformation and tumorigenesis of Rat-1 cells. METHODS： Retrovirus plasmids pLNSX-LMP1 and pBabe-IκBα constructed by gene recombination technique, were cotransfected respectively with nuclear factor-κB luciferase reporter （pNF-κB- luc） into 293 cells. The actions of LMP1 in activating NF-κB and IκBαin inhibiting NF-κB were measured by luciferase activity assay. Moreover, pLNSX-LMP1 and pBabe-IκBαwere transfected respectively into the ecotropic retrovirus packaging cell line PA317 to generate LMP1 retrovirus （RV-LMP1） and IκBαretrovirus （RV-IκBα. After Rat-1 cells were infected by RV-LMP1 alone or RV-LMP1 combined RV-IκBα their malignant transformation phenotype was detected by colony forming assay and nude mice tumorigenicity assay. RESULTS： When pLNSX-LMP1 and pBabe-IκB were cotransfected at a ratio of 1：1, IκBα inhibited LMPl-mediated NF-κB activation by 75%; and at a ratio of 3：1, it almost completely inhibited LMPl-mediated NF-κB activation. IκBαobviously inhibited LMPl-mediated malignant phenotype of Rat-1 cells.colony formation number on plates were significantly decreased from （368±7）/well and （287±17）/well to （59±6）/well and （8±2）/well （P〈0.001）. Foci in soft agarose were decreased from （477±13）/well and （347±10）/well to （61±15） /well and （95±7）/well （P〈0.001）. The ability of tumorigenicity in nude mice was markedly decreased= tumor volume was decreased from （1.61 ±0.23） cm^3 to （0.20±0.08） cm^3 （P〈0.001）. CONCLUSION= EBV-LMP1 could lead to transformation and tumorigenesis of Rat-1 cells by activating NF-κB.