Plasmin-Cellular Interactions in Breast Cancer Invasion and Metastasis.
Annual rept. 30 Sep 94-29 Sep 95,
VIRGINIA UNIV CHARLOTTESVILLE
Pagination or Media Count:
For breast cancer cells to invade or metastasize, a cascade of proteinases, including the serine proteinase plasmin, must be organized at the cell surface. In the first year of this research program, we demonstrated a unique mechanism whereby breast cancer cells bind plasmin. The putative receptor S cytokeratin 8 CK 8. CK 8 is a cytoskeletal protein however, using fluorescence microscopy and unoelectron microscopy, we demonstrated CK 8 on the external plasma membrane of non-permeablized breast cancer cells. We prepared a monoclonal antibody specific for a synthetic peptide corresponding to the C-terminal 13 amino acids of CK 8. This antibody bound specifically to breast cancer cells and inhibited binding of plasminogen to the same cells. Furthermore, we demonstrate that purified CK 8 not only binds plasminogen, but also tissue-type plasminogen activator. In the resulting ternary complex, the rate of plasminogen activation is significantly increased. This activity is duplicated by CK 8 which is recovered from conditioned medium of breast cancer cell lines. We are now developing the reagents to test the role of CK 8 in breast cancer invasion, using in vitro invasion models.
- Medicine and Medical Research
- Anatomy and Physiology