Effects of retinoids on normal and neoplastic human cells cultured in vitro.

The effects of retinoic acid on cultured human cells derived from normal and neoplastic tissues were studied. Retinoic acid consistently induced plasminogen activator synthesis by cells of mesenchymal origin (with the exception of adult skin fibroblasts) but not by cells of epithelial origin. The effect of retinoic acid was more pronounced than that of equimolar concentrations of retinol or retinyl acetate. Dexamethasone inhibited the retinoid-induced increase in plasminogen activator in lung- and foreskin-derived fibroblasts. Cells derived from normal or neoplastic tissues showed no consistent differences either in baseline rates of plasminogen activator release or in the magnitude of the retinoid effect.