Thrombospondin-1 (TSP-1) up-regulates matrix metalloproteinase-9 (MMP-9) expression through a novel receptor in gastric cancer cells

Abstract

Introduction: TSP-1 up-regulates MMP-9, a key protease in tumor cell invasion, in gastric cancer. We have also shown that angiocidin, a novel TSP-1 receptor, co-localizes with MMP-9 in gastric cancer. We hypothesize that angiocidin plays a central role in TSP-1 up-regulation of MMP-9 in gastric cancer cells. Methods: AGS gastric adenocarcinoma cells were incubated with exogenous TSP-1 or co-cultured with TSP-1-producing NHDF fibroblasts. TSP-1 expression was determined by ELISA and Western blot. The effect of TSP-1 on MMP-9 expression was determined by using anti-TSP-1 or anti-angiocidin antibodies. MMP-9 expression was determined by Western blot, zymography, and quantitative immunohistochemistry. Statistical significance was determined by ANOVA and Student’s t-test. Results: ELISA and Western blot showed a 20-fold difference in TSP-1 expression between NHDF and AGS cells (100 vs. 5 g/106 cells/24 hours of TSP-1, respectively, p < 0.01). Exogenous TSP-1 up-regulated MMP-9 production by AGS cells twofold (see Table and Fig.). TABLE—ABSTRACT 95MMP-9 Expression by Quantitative ImmunohistochemistryTreatment groupAGSAGS + TSP-1ASG + NHDFASG + NHDF + anti-TSP-1AGS/NHDF + anti-angiocidinCell No.1323∗12124∗∗15∗∗Numbers represent number of MMP-9-positive AGS cells per high power field.∗P < 0.01 vs. AGS.∗∗P < 0.01 vs. AGS + NHDF. Co-culturing AGS cells with TSP-1-producing NHDF fibroblasts up-regulated AGS cell MMP-9 expression tenfold (see Table and Fig.). MMP-9 expression was reduced 80% and 90% by anti-TSP-1 or anti-angiocidin antibodies, respectively (see Table and Fig.). Conclusions: We conclude that TSP-1, through angiocidin, up-regulates MMP-9 expression in gastric carcinoma cells. This effect is more prominent with tumor cell-stromal cell interaction.