RGD-recognizing integrins mediate interactions of human prostate carcinomacells with endothelial cells in vitro

BACKGROUND. Interactions of cancer cells with endothelium are a crucial ste p in metastatic invasion. RGD-recognizing integrins play a definitive role in these interactions. METHODS. Fluorescence-activated cell sorting (FACS) analysis df RGD-sensiti ve integrins in prostate epithelial cells was performed. Attachment inhibit ion assay was used to characterize functionality of particular integrins. P otential partners for RGD-binding integrins in human umbilical vein endothe lial cells (HUVEC) were identified by Western blotting and attachment inhib ition assay. To determine the RGD-flanking amino acids optimal for interact ions with prostate cell integrins, these cells were biopanned with a phage library. RESULTS. Different expressions of RGD-recognizing integrins and distinction s in RGD-dependent adhesion of nonmalignant and cancer cells were observed. Cancer but not control cells were detached from culture plastic by incubat ion with RGD peptide. Adhesion of carcinoma cells to HUVEC was RGD-sensitiv e, in contrast to nonmalignant cells. Antibodies against alpha 3, alpha 5, beta 1, and alpha v beta 3 inhibited interactions of carcinoma cells with H UVEC. Potential ligands for alpha 5 beta 1, alpha 3 beta 1, and alpha V bet a 3 integrins, fibronectin, and vitronectin, were detected on the HUVEC sur face. Several phages which preferentially bound to the surface of particula r prostate cells were selected. CONCLUSIONS. Interactions of prostate carcinoma with endothelium are mediat ed in part via alpha 5 beta 1, alpha 3 beta 1, and alpha v beta 3 integrins . Because these interactions are RGD-sensitive, synthetic RGD peptides with optimized flanking amino acids can potentially be used as antimetastatic a gents. (C) 1999 Wiley-Liss Inc.