ENHANCED MALIGNANT PROGRESSION OF NASOPHARYNGEAL CARCINOMA-CELLS MEDIATED BY THE EXPRESSION OF EPSTEIN-BARR NUCLEAR ANTIGEN-1 IN-VIVO

Nasopharyngeal carcinoma (NPC) is consistently associated with Epstein -Barr virus (EBV) and mostly classified as poorly differentiated squam ous cell carcinoma or undifferentiated carcinoma with early metastasis and a rapidly progressive clinical course. The EBV-encoded latent pro teins, Epstein-Barr nuclear antigen 1 (EBNA 1) and latent membrane pro teins (LMPs), may be expressed in NPC, but their biological effects ar e poorly understood. EBNA 1 may predispose B lymphocytes to lymphomage nesis in transgenic mice, but its biological effects in NPC are still unknown. This study investigated the biological effects of EBNA 1 by e xpressing it in an EBV-negative NPC cell line (HONE-1), which was then inoculated into both nude and severe combined immunodeficiency mice. The EBNA 1 caused HONE-1 cells to grow in a less differentiated patter n and to progress more rapidly, as well as increasing their tumourigen icity and metastatic capability. These data suggest that EBNA 1 may pl ay a critical role in the progressive evolution of NPC.