Latent membrane protein-1 of Epstein-Barr virus inhibits cell growth and induces sensitivity to cisplatin in nasopharyngeal carcinoma cells

Nasopharyngeal carcinoma is closely associated with Epstein-Barr virus (EBV ) and the EBV encoded latent membrane protein-1 expression (LMP1) is common ly found in the tumour cells. LMP1 has been shown to be involved in modulat ion of cell growth in B cells but the biological properties of LMP1 express ion in nasopharyngeal carcinoma cells are less defined. In this study, a fu ll length LMP1 gene was introduced into an EBV negative nasopharyngeal carc inoma cell line, CNE2, and five LMP1-expressing clones were isolated. Expre ssion of LMP1 did not confer cell growth advantage in CNE2 cells; instead, it induced growth inhibition both in vitro and in vivo. In addition, the LM P1 transfected cells were more susceptible to cisplatin-induced cell death and showed 1.4-4.0-fold increased sensitivity to cisplatin compared to the vector infected control clones. The effect of LMP1 on the balance of Bcl-2 and Bax ratio may play a role in inducing susceptibility to cisplatin-induc ed cell death. These results demonstrated that LMP1 did not confer growth a dvantage in CNE2 cells, suggesting that expression of LMP1 may not be cruci al in sustaining cell growth in established cell lines. Alternatively, LMP1 alone may not be sufficient to facilitate nasopharyngeal carcinoma cell gr owth and additional oncogenic factors may be needed along with LMP1 in modu lating the malignant property of nasopharyngeal carcinoma. (C) 2002 Wiley-L iss, Inc.