Differential binding to soluble nuclear receptors and effects on cell viability of retinol and retinoic acid in cultured retinoblastoma cells

Human retinoblastoma cells in culture contain soluble receptors for both ³H-retinol and ³H-retinoic acid which are separate and distinct as assessed by specificity, enzyme susceptibility and binding affinity. Total cellular binding of retinol correlates well with its rapid effect on cell mortality. A limited number of soluble nuclear receptor sites for ³H-retinoic acid but not ³H-retinol are observed after incubation of the ³H-retinoid with intact cells indicating a possible preferential effect of retinoic acid at the gene level.