Leukocyte function-associated antigen 1-dependent adhesion of rat hepatoma AH66F cells and inhibition by protein kinase C inhibitors.

When rat ascites hepatoma AH66F cells were incubated on a mesothelial cell (M-cell) layer for 1 hr, the adhesion rate of the cells to M-cells was ca. 46%. The protein kinase C (PKC) inhibitors, N-(2-methylpiperazyl)-5-isoquinolinesulfonamide (H-7) and N-ethoxycarbonyl-7-oxostaurosporine (NA-382), inhibited the adhesion of AH66F cells in a concentration-dependent manner, and the effect of NA-382 appeared after a treatment of more than 24 hr. The decreased adhesion rate after treatment with NA-382 for 48 hr was not further inhibited by addition of monoclonal antibodies of leukocyte function-associated antigen-1 (LFA-1) alpha- and beta-chains and intercellular adhesion molecule-1 (ICAM-1) (WT.1, WT.3, and 1A29, respectively). The expression of LFA- 1 alpha- and beta-chains on the surface of the plasma membrane of AH66F cells was decreased after treatment with NA-382 for 48 hr; treatment with a potent inhibitor of cyclic AMP-dependent protein kinase, N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide (H-89), did not affect the cell adhesion and the expression of LFA-1 molecules on AH66F cells. These results suggest that the expression of LFA-1 molecules on AH66F cells is regulated through the PKC pathway.