Effects of Tubeimoside 1 on Apoptosis of Human Umbilical Vein Endothelial Cells and Inhibition of Tumor-induced Angiogenesis

Abstract: The present study was conducted to investigate the effects of tubeimoside 1 (TBMS1) isolated from Bolbostemma paniculatum (Maxim.) Franquet on apoptosis of human umbilical vein endothelial cells (HUVECs) and inhibition of tumor-induced angiogenesis. Cell growth inhibitory effect of TBMS1 on HUVECs was measured by MTT assay; the apoptotic induction by TBMS1 was determined by fluorescence microscopy and flow cytometry; the effect of TBMS1 on migration of HUVECs was measured on transwell model; the chick embryochorioallantoic membrane (CAM) assay was adopted to evaluate the effects of various doses of the TBMS1 on the angiogenesis induced by CNE-2Z cells; the immunohistochemical staining assay was adopted to examine the intratumoral microvessel density (MVD) and the expressions of several angiogenesic factors in Lewis lung carcinoma tissue of nude mice. The proliferation of HUVECs was inhibited by TBMS1， and the effect was time- and concentration-dependent. The values of IC₅₀ for the effect of TBMS1 on HUVECs at 24， 48， 72 h are 24.2， 21.4， 17.9 μmol/L， respectively. TBMS1-treated HUVECs showed typical morphologic and cellular evidences of apoptosis. 20.0 μmol/L of TBMS1 decreased the percentage of migrating HUVECs by 58.4%. TBMS1 exerted effective inhibitory effects on CNE-2Z cells-induced angiogenesis in CAM in a concentration-dependent manner. There was an obvious decrease of MVD in tumor tissue of nude mice treated by TBMS1. The expressions of VEGF， bFGF and PDGF in the TBMS1-treated tumor tissue were evidently down-regulated. TBMS1 is effective against anigogenesis both in vitro and in vivo. Apoptotic induction and inhibition of migrating and down-regulation of the expressions of angiogenesic factors mediated by TBMS1 in HUVECs may be responsible to angiogenesis of TBMS1.

CSTR: 32200.14.cjcb.2008.06.0014