Antisense-mediated reduction in thrombospondin-1 expression reduces cell motility in malignant glioma cells

Thrombospondin-1 (TSP-1) is a multifunctional matrix protein implicated in cancer cell adhesion, migration, invasion, inhibition of angiogenesis and a ctivation of latent transforming growth factor-beta. The involvement of TSP -1 in the motility of malignant glioma cells was investigated by transfecti on of TSP-1 complementary deoxyribonucleic acid (cDNA) sense and antisense expression vectors into the glioblastoma cell line T98G-G7 that secretes hi gh amounts of TSP-1. TSP-1 production in the 3 antisense cDNA-transfected c lones was significantly reduced to 51%, 43% and 47% compared to the host T9 8G-G7 cells. Motility of the 3 clones was evaluated by invasion assay and c ompared to the motility of host T98G-G7 cells and 2 sense-transfected clone s. Migration of cells was significantly reduced in the 3 antisense-transfec ted clones with reduced TSP-1 production to 56%, 61% and 43% compared to th e host T98G-G7 cells. The host T98G-G7 and another TSP-1-secreting A172 and YMG5 glioblastoma cells were also treated with a synthetic peptide, WSHWSP WSSCSVTCG, which includes 3 consecutive sequences of the adhesion sites in the TSP-I molecule and with a control peptide. The synthetic peptide signif icantly inhibited the migration of T98G-G7 and A172 cells in a dose-related manner. Maximum inhibition of migration was achieved by 100 mug/ml of the peptide and the reduction of cell motility compared to untreated cells was 34.6% and 53.9%, respectively. On the other hand, the inhibition of migrati on by the peptide was minimal in YMG5 cells, which secretes a smaller amoun t of TSP-1 than T98G-G7 and A172 cells. These results suggest that TSP-I se creted by malignant glioma cells is involved in the motility of glioma cell s. (C) 2001 Wiley-Liss, Inc.