Control of the expression of thrombospondin 1 in human breast cancer cell lines.

Thrombospondins (TSP) are adhesive glycoproteins which are synthesized, secreted and incorporated into the extracellular matrix of a variety of cells, including mammary epithelial cells. These molecules are included in a gene family that is composed of at least four members. Their roles in the mammary gland are associated with two contradictory functions: antiangiogenesis and tumor invasiveness. To define the role of TSP1 in the mammary gland, the steady-state level of TSP1 mRNA in both normal (HB100) and breast cancer cell lines (MCF-7, T47-D, MDA-MB-231, ZR-75-1) was established. We also observed that the TSP1 protein synthesis is down regulated in breast cancer cell lines as compared to the HB100 cell line. These results show that TSP1 is expressed in well differentiate cells, and suggest that TSP1 could be associated with the antiangiogenesis.