Biological activities of 2α-substituted analogues of 1α,25-dihydroxyvitamin D3 in transcriptional regulation and human promyelocytic leukemia (HL-60) cell proliferation and differentiation

Abstract

Biological activities of 2α-substituted 1α,25-dihydroxyvitamin D3 analogues were evaluated in vitro. Their binding affinity was examined with calf thymus cytosolic vitamin D receptor (VDR) and rat plasma vitamin D-binding protein (DBP). In addition, the transcriptional activity of the analogues was measured using a rat 25-hydroxyvitamin D3-24- hydroxylase gene promoter, a human osteocalcin gene promoter, and VDR-GAL4 system. This study investigated the biological activities of 2α-substituted analogues in comparison with 2β-substitued analogues at the molecular level, with regard to the structural differences of alkyl, hydroxyalkyl, hydroxyalkoxy substituents at the 2-position of 1α,25-dihydroxyvitamin D3. © 2006 Pharmaceutical Society of Japan.