Abstract
Nasopharyngeal carcinoma (NPC) is a malignant squamous epithelial tumor of the nasopharynx, which occurs at high frequencies in Southeast Asia, particularly southern China and Taiwan. Previous studies based on serological and molecular biological evidence have indicated that Epstein-Barr virus is one of the etiological factors of the Nasopharyngeal carcinoma. These studies have further indicated that an EBV-encoded oncoprotein, latent membrane protein 1 (LMP1), is expressed in 60% of NPC tissues. The present work is to investigate the immune responses of BALB/c mice induced with NPC-LMP1 gene by electroporation in vivo. To achieve this goal, the GST-NLMP1 (186-381) fusion protein and its polyclonal antidoby were obtained for setting up an ELISA system for determination of antibody responses in the DNA immunized BALB/c mice. Our result obtained from transient transfection experiments confirmed the expression of pCMV-NLMP1 and pCMV-GM-CSF in 293 cell lines. Histochemical analysis of muscles injected with the pCMV-LacZ showed that in vivo electroporation increased gene expression in the muscle of mice and was more efficient than simple intramuscular DNA injection. Nevertheless neither antibody against GST-NLMP1 (186-381) fusion protein nor the specific CTL activity was produced. Finally, the E2+P18TI cell line, a superior NPC-LMP1 tumor model, was established from the in vivo passaged tumor mass of a BALB/c mouse inoculated with E2+P18 cell lines. The tumor formation rate of E2+P18TI cell line was two fold higher than that of the E2+P18 cell line. In summary, the results of this study suggest the need to reconsider efficacy for DNA vaccination against NPC.