[Biological and antitumor effects of CD40L on ovarian cancer cell line OVHM]

Accumulative evidences have indicated the importance of CD40-CD40L receptor-ligand pair in the initiation and regulation of human immune response. Whether triggering CD40-CD40L signaling pathway could induce antitumor effects in ovarian cancer cells is still unclear. This study was to investigate the biological and antitumor effects of CD40L on ovarian cancer cell line OVHM (CD40-positive).

CD40L cDNA was transfected into OVHM cells by lipofectamine 2000. Immunofluorescent technique and flow cytometry were used to evaluate the expression of CD40, CD40L, MHC-I, MHC-II, CD80, CD86. Cell proliferation was detected by MTT assay. CD40L/OVHM and OVHM cells were inoculated hypodermically into C57BL/6N x C3H/He F1 (B6C3F1) mice and BALB/c nude mice simultaneously. Tumor volume was measured. The production of IFN-gamma secreted by the spleen cells from CD40L/OVHM and OVHM cell-inoculated mice co-cultured with 20 Gy-irridiated OVHM cells were measured with enzyme-linked immunosorbent assay (ELISA).

Expression of CD40L in OVHM/CD40L cells was significantly higher than that in OVHM cells (P<0.05). Moreover, the expression of co-stimulatory molecules CD80 and CD86 of CD40L/OVHM was increased (P<0.05). The proliferation rate of parental and CD40L-expressed OVHM cells were not different. Although, delayed tumor growth was observed when CD40L-expressing OVHM cells and OVHM cells were injected simultaneously and contralaterally, the tumor growth of OVHM and CD40L/OVHM in BALB/c nude mice was not different. The amounts of IFN-gamma secreted by the co-culture of irradiated OVHM cells with spleen cells from mice injected with CD40L/OVHM were much higher than those from OVHM/parental cell inoculated and naive mice.

The forced expression of CD40L cDNA in OVHM cells can increase the immunogenicity, and thus develop antitumor effects against OVHM-incubated mice. In vivo immunization of immunocompetent mice with CD40L/OVHM improves the generation of cytotoxic lymphocytes against parent ovarian cancer cells.