CHARACTERIZATION OF INTEGRIN SUBUNITS, CELLULAR ADHESION AND TUMORGENICITY OF 4 HUMAN PROSTATE CELL-LINES

Cellular adhesion to extracellular matrix proteins via integrin molecu les is a major factor in the process of invasion and metastasis of hum an tumor cells. Four human prostate cell lines were characterized acco rding to the presence and quantity of integrin subunits, the ability o f the cells to attach to extracellular substrates and the capacity of the cells to form tumors in severe combined immunodeficient (SCID) mic e. All four human prostate cell lines expressed three to five integrin s on their cell surfaces. The DU145, PC3 and 431P cells expressed prim arily alpha3, alpha5, and alpha6 integrin at similar levels. These cel l lines expressed the subunits beta1, beta3, and beta4 with beta1 pred ominant. The DU145 cells preferred attachment to fibronectin, followed by laminin and vitronectin. Approximately 50%-60% of the binding of D U145 cells to fibronectin and laminin was dependent on the function of alpha5beta1 and alpha6 respectively. The cell line LNCaP differed in its low expression of the alpha3 subunit, 95% of cellular adhesion to fobronectin and laminin being integrin-dependent and its inability to attach to vitronectin, in spite of surface expression of alpha(v)beta3 . All the cell lines except for LNCaP readily formed tumors within SCI D mice and the expression of alpha3, alpha6, beta1 and beta4 integrin subunits was preserved in the resulting tumor tissue. The altered adhe sion properties of the LNCaP cells may explain their altered tumorigen icity.