CONTROL OF THE EXPRESSION OF THROMBOSPONDIN-1 IN HUMAN BREAST-CANCER CELL-LINES

Thrombospondins (TSP) are adhesive glycoproteins which al e synthesize d, secreted and incorporated into the extra-cellular matrix of a varie ty of cells, including mammary epithelial cells. These molecules are i ncluded in a gene family that is composed of at least foul members. Th eir roles in the mammary gland al e associated with two contradictory functions: antiangio-genesis and tumor invasiveness. To define the rol e of TSP1 in the mammary gland, the steady-state level :of TSP1 mRNA i n 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 prote in 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 wi th the antiangiogenesis.