Expression of integrins in human cultured mesothelial cells: The roles in cell-to-extracellular matrix adhesion and inhibition by RGD-containing peptide

Abstract

Integrins play key roles in cell-to-cell and cell-to-extracellular matrix (ECM) adhesion. We investigated integrin expression on pleural mesothelial cells (PMCs) and the inhibitory effect of arginine-glycine-asparate (RGD)-containing peptide on the adhesion of PMCs to fibronectin and collagen. Using flow cytometry and immunostaining, PMCs freshly isolated from pleural effusions and one mesothelial cell line were screened for different integrins. Intact pleural tissue was evaluated by immunohistochemistry. The adhesion of Met-5A cells to fibronectin and collagen types I, III and IV was assayed with prior treatment of various concentrations of glycine-arginine-glycine-aspartate-serine (GRGDS). On primary PMCs, α2, α3, α5, β1, β3 and αvβ3 were highly expressed (>70%); α1 expression was intermediate (30-70%); and α4 and α6 expressions were low (<30%). On Met-5A cells, α3, α5, α6 and β1 were highly expressed (>70%); α1 was intermediate (30-70%); and α2, α4, β3 and αvβ3 were low (<30%). The patterns of immunostaining on pleural tissues were similar to the results of flow cytometry for primary PMCs except for β3. There was no statistically different expression in various disease states (transudate vs. exudate, benign vs. malignant). The inhibitory effect of GRGDS peptide on Met-5A cell adhesion to all four matrix proteins was dose-dependent. © 2001 Harcourt Publishers Ltd.