EXPRESSION OF ALPHA-V INTEGRINS AND VITRONECTIN RECEPTOR IDENTITY IN BREAST-CANCER CELLS

In the present study we have used fluorocytometry and immunoprecipitat ion to characterize the expression of alpha v-containing integrins in a panel of eight human breast cancer cell lines and one normal human m ammary epithelial line. We show that the classical vitronectin recepto r alpha v beta 3 is expressed in only one cell line (MDA-MB-231), wher eas alpha v beta 5 is expressed on all breast cancer cell lines and al pha v beta 1 is expressed on the majority. Using adherence assays to p urified ligands in the presence and absence of function-blocking monoc lonal antibodies, we have demonstrated that alpha v beta 5 mediates ad hesion to vitronectin in the majority of these cells. in one cell line , ZR75-1, alpha v beta 1 contributes significantly to adhesion to immo bilized vitronectin. The formation of local adhesions containing the a lpha v and beta 1 subunits on vitronectin is also demonstrated by indi rect immunofluorescence.