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

AIM: To investigate the effects of mifepristone on the invasive and metastatic potential of human gastric adenocarcinoma cell line MKN-45 and its mechanisms. METHODS: After incubation with various concentrations of mifepristone (5, 10, 20 mu mol/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 beta 3 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. RESULTS: Mifepristone dose-dependently inhibited the heterotypic adhesion to Matrigel of MKN-45 cells. The inhibition was accompanied by a significant down-regulation of integrin beta 3 expression in the cells. After incubation with 5, 10, 20 mu mol/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. CONCLUSION: 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.