[Antitumor research on mouse melanoma with combined application of Newcastle disease virus and its HN gene]
ABSTRACT
BACKGROUND & OBJECTIVE: Although Newcastle disease virus (NDV) shows antitumor effect on many tumors, its mechanism is unclear. Hemagglutinin-neuraminidase (HN) gene was found to play an important role in NDV antitumor effect and HN protein located on tumor cell surface. This research was to evaluate the possibility of HN protein as a foreign antigen of tumor cell and the antitumor effect of the combined application of HN gene and NDV.
METHODS: C57BL/6 mice were subcutaneously inoculated with 2 x 10(5) B16 tumor cells in the right hindlimb. Combination group: on 2nd day post-inoculation, the recombinant plasmid containing HN gene was injected intramuscularly in the left hindlimb; on 7th day post-inoculation, 2 x 10(9) pfu NDV was administrated intratumorally. The alone HN gene group, NDV group, and PBS control group were treated as above. The antitumor effect was observed through tumor suppression rate, the antitumor mechanisms were researched with specific cytotoxic T lymphocyte (CTL) assay, and the expression determination of HN protein, ICAM-I, and CD48 on the B16 tumor cells.
RESULTS: The antitumor efficacy of the combined application of NDV and its HN gene increased compared with NDV,and its HN gene alone, the tumor suppression rates were 82.8%, 41.0%, and 56.6%; the specific CTL activity were 18.4%, 10.1%, and 4.4%, respectively. Furthermore, the expression of HN gene had been detected, and the expression of ICAM-I and CD48 were up-regulated on the tumor cells after NDV injection.
CONCLUSION: HN protein located on the surface of tumor cells and mediated the specific repulsion to tumor cells; the antitumor efficacy increased after the combined application of NDV and its HN gene.