Effects of recombinant human CD40 ligand on biological behavior of ovarian cancer SKOV3 cells in vitro

AIM: To investigate the effect of recombinated human CD40 ligand (rhCD40L) on the biological behavior of ovarian cancer SKOV3 cell line in vitro.METHODS: After the SKOV3 cells were incubated with different concentrations of rhCD40L for various times, the cell proliferation was determined by MTT assay.The expression of the co-stimulatory molecules or adhesion molecules on SKOV3 cells and the changes of tumor necrosis factor receptor associated factor (TRAFs) inside the cells were measured by flow cytometry and direct immunofluorescence.Annexin V and PI dual color label assay were used to detect cell apoptosis or death in culture contained with rhCD40L.RT-PCR assay was employed to determine the change of apoptosis related gene c-myc, bcl-2 and bcl-xl expression in SKOV3 cells.RESULTS: rhCD40L inhibited proliferation of SKOV3 cells at concentration of 100 μg/L (0.65±0.10 vs 0.81±0.05) and reached a peak at concentration of 10 mg/L (0.13±0.12 vs 0.83±0.15, P＜0.01).The inhibitory effects showed a dose dependent manner.Cell cycle analysis showed that cell division was blocked in G1 phase.Increasing proportion of apoptosis of SKOV3 cells was related to up-regulation of CD95 expression (42.4% vs 59.2%, P＜0.05) and down-regulation of anti-apoptosis genes such as bcl-2 and bcl-xl expressions after incubation with rhCD40L.TRAF 2, 5 and 6 expressed highly in SKOV3 cells.The expression of TRAF 2 (81.3%±9.2% vs 50.4%±5.3%，P＜0.05), TRAF5 (47.2%±7.2% vs 7.2%±2.1%, P＜0.01) and TRAF6 (44.5%±6.3% vs 5.1%±1.1%, P＜0.01) was down-regulated and expression of TRAF 3 (25.2%±6.2% vs 68.8%±5.3%, P＜0.01) was up-regulated after co-culture with rhCD40L, but there was no effects found on the expression of TRAF 1 (4.3%±1.2% vs 5.1%±1.4%) and TRAF4 (7.4%±1.2% vs 8.1%±1.4%).CONCLUSION: By down-regulating expression of bcl-2, bcl-xl and changing expression profile of TRAF, rhCD40L inhibits the growth of SKOV3 cells by blocking the cell cycle progress in G1 and promotes the cells to apoptosis.