Characterization of integrin subunits, cellular adhesion and tumorgenicity of four human prostate cell lines

Abstract

Cellular adhesion to extracellular matrix proteins via integrin molecules is a major factor in the process of invasion and metastasis of human tumor cells. Four human prostate cell lines were characterized according to the presence and quantity of integrin subunits, the ability of the cells to attach to extracellular substrates and the capacity of the cells to form tumors in severe combined immunodeficient (SCID) mice. All four human prostate cell lines expressed three to five integrins on their cell surfaces. The DU145, PC3 and 431P cells expressed primarily α₃, α₅, and α₆ integrin at similar levels. These cell lines expressed the subunits β₁, β₃ and β₄ with β₁ predominant. The DU145 cells preferred attachment to fibronectin, followed by laminin and vitronectin. Approximately 50%–60% of the binding of DU145 cells to fibronectin and laminin was dependent on the function of α₅β₁ and α₆ respectively. The cell line LNCaP differed in its low expression of the α₃ 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 α_vβ₃. All the cell lines except for LNCaP readily formed tumors within SCID mice and the expression of α₃, α₆, β₁, and β₄ integrin subunits was preserved in the resulting tumor tissue. The altered adhesion properties of the LNCaP cells may explain their altered tumorigenicity.