Effects of mifepristone on invasive and metastatic potential of human gastric adenocarcinoma cell line MKN-45 in vitro and in vivo.

Abstract

To investigate the effects of mifepristone on the invasive and metastatic potential of human gastric adenocarcinoma cell line MKN-45 and its mechanisms. After incubation with various concentrations of mifepristone (5, 10, 20 micromol/L), the adhesion to artificial basement membrane, Matrigel, and the migration of MKN-45 cells were assayed using MTT assay and Transwell cell culture chambers, respectively. Enzyme- linked immunoabsorbent assay (ELISA) and flow cytometry were used to determine the expression of vascular endothelial growth factor (VEGF) and integrin beta3 in the cells. After subcutaneous transplantation of MKN-45 cells in nude mice, mifepristone (50 mg/kg.d) was administrated subcutaneously for 8 wk to assess its effects on tumor metastasis. Immunohistochemical analysis was used to detect the expression of VEGF and microvascular density (MVD) in xenografted tumors. Mifepristone dose-dependently inhibited the heterotypic adhesion to Matrigel of MKN-45 cells. The inhibition was accompanied by a significant down-regulation of integrin beta3 expression in the cells. After incubation with 5, 10, 20 micromol/L mifepristone, the number of migrated MKN-45 cells was 72+/-8, 50+/-6, 41+/-5 in experiment group, and 94+/-16 in control group (P<0.01). Meanwhile, secreted VEGF protein of MKN-45 cells in mifepristone-treated group (14.2+/-2.9, 8.9+/-3.1, 5.4+/-2.1 ng/g per liter) was significantly lower than that in control group (22.7+/-4.3 ng/g per liter, P<0.01). In vivo, mifepristone decreased the number of metastatic foci in lungs of nude mice and down-regulated the expression of VEGF and MVD in the xenograted tumors. Mifepristone can effectively inhibit the invasive and metastatic potential of human gastric adenocarcinoma cell line MKN-45 in vitro and in vivo through inhibition of heterotypic adhesion to basement membrane, cell migration and angiogenesis.