Role of vascular endothelial growth factor receptor in the pro-proliferation activity of CD40-CD40L in AGS gastric cancer cells

Background: CD40 is a type α-membrane protein of the tumor necrosis factor receptor super-family, and CD40- induced responses may mediate growth and angiogenesis in carcinoma cells. Objectives: Define the effect of CD40 ligation on AGS gastric cancer cell line and the role of vascular endothelial growth factor/vascular endothelial growth factor receptor (VEGF/VEGFR) signals in this process. Methods: We treated AGS cells with 1 μg/mL soluble CD40 ligand (sCD40L) with or without pre-incubation of either anti-VEGF mAb (MAB293) or VEGFR tyrosine kinase inhibitor (SU5416). We determined the growth effects by cell counts or [³H]-thymidine incorporation assay and VEGF levels in cell-free supernatant using enzymelinked immunosorbent assays. Results: The engagement of CD40-induced AGS cells proliferation accompanied by a significant increase autocrine VEGF through PI3K activation (p <0.05), and exogenous VEGF alone had no effect on spontaneous cell growth. SU5416 with a concentration of 8 μM lead to a dramatic decrease in cell survival induced by sCD40L (p <0.05), whereas MAB293 did not have the similar effect (p >0.05). Conclusion: CD40-CD40L interaction promoted AGS cancer cell line proliferation through a VEGFR-dependent signal pathway in the presence of an internal autocrine loop.