Suppression of murine B-cell lymphoma growth by trichosanthin through anti-angiogenesis

Studies have suggested trichosanthin (TCS) exerts antitumor activity mainly through direct cytotoxicity toward cancer cells and immune regulation. In this study, we conducted the proliferation and apoptosis assay on A20 cells and endothelial cells (ECs) with different concentrations of TCS and investigated the levels of gene expression linked to angiogenesis. Herein, a new mechanism that TCS inhibits murine B-cell lymphoma growth by anti-angiogenesis was reported. First, TCS inhibit tumor growth and prolonged survival significantly in vivo, and TCS depressed the formation of new blood vessels around the tumor in a dose-dependent manner. Further studies showed that the platelet endothelial cell adhesion molecule-1 (PECAM-1/CD31)-positive endothelial cell numbers, and the serum levels of MMP-2 and MMP-9 were also lower in the study group than controls. However, TCS did neither change the ratio of T cells and NK cells in the spleen of treated mice nor affect the proliferation and apoptosis of A20 cells in vitro. Additionally, the newly formed blood vessels in chorioallantoic membranes treated with TCS were significantly reduced. Last, TCS may suppress the proliferation, induce apoptosis and decrease tube formation and migration of endothelial cells (ECs). And, the mRNA and protein levels of VEGF in ECs treated with TCS were lower than that in the control group. These findings confirm that inhibitory effect of TCS on A20 murine B-cell lymphoma growth is mediated via anti-angiogenesis, and which may be associated with the down-regulation of VEGF and MMPs expression. This is an indication that TCS may represent a natural anti-angiogenic drug for lymphoma therapy.