[Effects of Epstein-Barr virus latent membrane protein 1 mediated by nuclear factor-kappaB on transformation and tumorigenesis of rat-1 cells].
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-IkappaBalpha, constructed by gene recombination technique, were cotransfected respectively with nuclear factor-kappaB luciferase reporter (pNF-kappaB-luc) into 293 cells. The actions of LMP1 in activating NF-kappaB and IkappaBalpha in inhibiting NF-kappaB were measured by luciferase activity assay. Moreover, pLNSX-LMP1 and pBabe-IkappaBalpha were transfected respectively into the ecotropic retrovirus packaging cell line PA317 to generate LMP1 retrovirus (RV-LMP1) and IkappaBalpha retrovirus (RV-IkappaBalpha). After Rat-1 cells were infected by RV-LMP1 alone or RV-LMP1 combined RV-IkappaBalpha, their malignant transformation phenotype was detected by colony forming assay and nude mice tumorigenicity assay.


RESULTS
When pLNSX-LMP1 and pBabe-IkappaB were cotransfected at a ratio of 1:1, IkappaBalpha inhibited LMP1-mediated NF-kappaB activation by 75%û and at a ratio of 3:1, it almost completely inhibited LMP1-mediated NF-kappaB activation. IkappaBalpha obviously inhibited LMP1-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) cm3 to (0.20+/-0.08) cm3 (P<0.001).


CONCLUSIONS
EBV-LMP1 could lead to transformation and tumorigenesis of Rat-1 cells by activating NF-kappaB.
Zhang
Zhi-Wei
ZW
Cancer Research Institute, Xiangya Medical College, Central South University, Changsha, Hunan, PR China.
He
Zhi-Min
ZM
Zhou
Min
M
Zhang
Qiong
Q
Yu
Yan-Hui
YH
Chen
Zhu-Chu
ZC
D000818:Animals; D002460:Cell Line; D002471:Cell Transformation, Neoplastic; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D006801:Humans; D020672:I-kappa B Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008819:Mice, Nude; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009369:Neoplasms / Q000209:etiology*; D010957:Plasmids; D051381:Rats; D012190:Retroviridae / Q000235:genetics; D014162:Transfection; D014763:Viral Matrix Proteins / Q000235:genetics / Q000378:metabolism*
C037662:EBV-associated membrane antigen, Epstein-Barr virus; D020672:I-kappa B Proteins; D016328:NF-kappa B; C000606204:NFKBIA protein, human; C000606205:Nfkbia protein, mouse; C000606206:Nfkbia protein, rat; D014763:Viral Matrix Proteins; D000072000:NF-KappaB Inhibitor alpha