Expression of retinoic acid receptor genes and the ligand-binding selectivity of retinoic acid receptors (RAR's).

Retinoids of a structurally new type, 4-(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthalenylcarbamoyl)benzoic acid (Am80) and (E)-4-[3-(3,5-di-tert-butylphenyl)-3-oxo-1-propenyl]-benzoic acid (Ch55), were used for the investigation of retinoid receptors in some human cell lines. Previously, using these retinoids, we have established that HL-60 cells possess two retinoid receptors, RAR-alpha and RAR-beta. In this paper, we report coexpression of RAR-alpha- and RAR-beta-genes established by Northern analysis. Further, the binding selectivity of the RAR products toward all-trans-retinoic acid (RA), Am80 and Ch55 was studied by filter binding assay. The affinity of the ligands toward RAR-alpha decreased in the order of Ch55 greater than RA greater than Am80. The affinity of the ligands toward RAR-beta decreased in the order of Ch55 greater than Am80 greater than RA.