[Transformation function of human bronchial epithelial cell by latent membrane protein1 encoded by Epstein-Barr virus...

Although some results show that latent membrane protein 1 (LMP1) may play an important role in the development of epithelium-derived tumors. There are few studies on the relationship between LMP1 and normal epithelial cell. So this study was designed to evaluate the effect of EBV LMP1 on cell transformation in human bronchial epithelial (HBE) cell and its mechanism.

Retrovirus expression vectors (LMP1 and LMP1+hTERT) were transfected into HBE cells and selected with the appropriate drugs to get resistant cells. The biological characteristics were studied by cell growth curve, colony formation analysis, and the determination of telomerase activity and protein expression of Cyclin A, p21, and CDK4.

wt-LMP1 together with hTERT gene transfected cells grew rapidly than HBE/wt-LMP1 cells. Soft agar plating rates of HBE/wt-LMP1-hTERT, HBE/wt-LMP1, and HBE/pLNSX+pBabe were 22.98%, 16.94%, and 8.85%, respectively. The activities of telomerase were 2.825, 2.441, and 1.876, respectively. In addition, there was no difference of protein expression of CDK4 among these groups. However, HBE/wt-LMP1-hTERT and HBE/wt-LMP1 cells had low-level p21 and high-level cyclin A protein expression than the vector groups.

The results suggest that LMP1 is in tandem with hTERT in promoting cell proliferation and transformation through modulating expression level of cyclin A and p21 protein.