OBJECTIVETo elucidate the regulation of the phosphorylation of epidermal growth factor receptor (EGFR) by the EB virus encoded latent membrane protein 1 (LMP1) in nasopharyngeal carcinoma cell line.

METHODSThe levels of EGFR expression and phosphorylation in pTet-on LMP1 HNE2 cell, a nasopharyngeal carcinoma (NPC) cell line, in the dynamic expression of LMP1 induced by different concentrations of doxycycline (Dox) were observed. The EGFR dominant negative mutant and LMP1 antisense expression plasmid were transiently transfected into pTet-on LMP1 HNE2 cells by lipofectamine, and the changes in EGFR phosphorylation were observed by immunocoprecitation and Western blot. The changes in EGFR phosphorylation were observed after EGF treatment.

RESULTSIn pTet-on LMP1 HNE2 cells, Dox-induced LMP1 upregulated EGFR expression and phosphorylation in a dose-dependent manner. After EGFR dominant negative mutant was transfected into pTet-on LMP1 HNE2 cells, the increase of EGFR phosphorylation was inhibited completely. When LMP1 antisense expression plasmid was transfected into pTet-on LMP1 HNE2 cells, the levels of EGFR phosphorylation were also inhibited significantly. Meanwhile, after EGF had been added into pTet-on LMP1 HNE2 cells, increase of EGFR phosphorylation was induced, but it was completely blocked by EGFR dominant negative mutant and the introduction of LMP1 antisense.

CONCLUSIONEB virus encoded LMP1 not only induces the dose-dependent expression of EGFR, but also the dose-dependent phosphorylation of EGFR. The phosporylation of EGFR may play a vital role in the development of nasopharyngeal carcinoma.