THROMBOSPONDIN-1 (TSP-1) PROMOTES THE INVASIVE PROPERTIES OF HUMAN BREAST-CANCER

TSP-1 is a matrix-bound adhesive glycoprotein, which plays a role in t umor cell proliferation and tumor angiogenesis. The purpose of this st udy was to investigate the effect of TSP-1 on breast tumor cell invasi on. Tumor cell invasion assays were performed using a modified Boyden chamber apparatus with collagen-coated membranes. Four breast cell lin es were studied in serum-free media: the malignant MDA-MB-231, SKBR-3, and MCF-7 cell lines, and the benign MCF-10A cell line. Invasion was measured as the summation of the number of cells in five representativ e high power fields (400x) traversing the collagen barrier after a 3-h r incubation period. The effect of an anti-TSP-1 antibody (100 mu g/ml ) was also evaluated in the malignant cell lines. Statistical analysis was performed by ANOVA and Student's unpaired t test. TSP-1 promoted a dose-dependent increase in invasion as compared to buffer controls i n all three malignant cell lines. TSP-1 (100 nM) promoted a greater th an five-fold increase over controls in tumor cell invasion for MDA-MB- 231, SKBR-3, and MCF-7 cell lines (P < 0.005). TSP-1 had no effect on the invasiveness of the benign cell type MCF-10A. Anti-TSP-1 antibody inhibited TSP-1 promoted invasion in the MDA-MB-231, SKBR-3, and MCF-7 cell lines by 45, 48, and 39%, respectively (P = 0.003, 0.044, 0.047) . TSP-1 promotes tumor cell invasion of collagen by breast cancer cell s. Therapy designed to inhibit TSP-1 may prevent invasion and metastas is in breast cancer. (C) 1996 Academic Press, Inc.