title: Differential activities of 1alpha,25-dihydroxy-16-ene-vitamin D(3) analogs and their 3-epimers on human promyelocytic leukemia (HL-60) cell differentiation and apoptosis.
abstract: To clarify physiological role of the carbon 3 (C-3) epimerization of 1alpha,25(OH)(2)D(3) and biologic significance of a 3-epi metabolite of 1alpha,25(OH)(2)D(3), we examined biologic activities of the 3-epimers of 1alpha,25(OH)(2)D(3) and 1alpha,25(OH)(2)-16-ene-D(3) analogs in terms of modulation of cell cycle phase distribution and cell-surface CD11b antigen expression of HL-60 cells, transactivation of vitamin D target genes in transfected cells, stimulation of VDR/RXRalpha heterodimer formation in a rabbit reticulocyte lysates transcription/translation system, stimulation of VDR/RXRalpha/VDRE complex formation, and induction of HL-60 cell apoptosis. The analogs tested here were 1) 1alpha,25(OH)(2)D(3), 2) 1alpha,25(OH)(2)-3-epi-D(3), 3) 1alpha,25(OH)(2)-16-ene-D(3), 4) 1alpha,25(OH)(2)-16-ene-3-epi-D(3), 5) 1alpha,25(OH)(2)-16-ene-23-yne-hexafluoro(F(6))-D(3), 6) 1alpha,25(OH)(2)-16-ene-23-yne-hexafluoro(F(6))-3-epi-D(3), 7) 1alpha,25-(OH)(2)-16-ene-20-epi-23-yne-D(3), and 8) 1alpha,25(OH)(2)-16-ene-20-epi-23-yne-3-epi-D(3). When compared to the 3-natural (beta) analogs, the 3-epi (alpha) analogs were biologically significantly less active. The findings support the hypothesis that the C-3 epimerization is an inactivation pathway of 1alpha,25(OH)(2)D(3) and its analogs in vitamin D target tissues. We also found that the 3-epi analogs, but not the 3-natural (beta) analogs, were the potent inducers of apoptosis of HL-60 cells. These results suggest that the analogs could be divided into two groups, in which the 3-epi analogs were the potent inducers of apoptosis of HL-60 cells, and the 3-natural analogs were the potent modulators of HL-60 cell growth and differentiation. This is the first report demonstrating that the 3-epimerization of the hydroxyl group at C-3 of the A-ring of 1alpha,25(OH)(2)D(3) plays an important role to modulate HL-60 cell differentiation and apoptosis.
authors.affiliation: Department of Hygienic Sciences, Kobe Pharmaceutical University, Motoyamakita-machi, Higashinada-ku, Kobe, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Nakagawa
authors.forename: Y
authors.initials: Y
authors.lastname: Sowa
authors.forename: M
authors.initials: M
authors.lastname: Kurobe
authors.forename: K
authors.initials: K
authors.lastname: Ozono
authors.forename: M L
authors.initials: ML
authors.lastname: Siu-Caldera
authors.forename: G S
authors.initials: GS
authors.lastname: Reddy
authors.forename: M R
authors.initials: MR
authors.lastname: Uskokovic
authors.forename: T
authors.initials: T
authors.lastname: Okano
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002117:Calcitriol / Q000031:analogs & derivatives / Q000494:pharmacology*; D002417:Cattle; D002453:Cell Cycle / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects; D019281:Dimerization; D018922:HL-60 Cells / Q000187:drug effects; D006801:Humans; D015473:Leukemia, Promyelocytic, Acute / Q000473:pathology*; D018168:Receptors, Retinoic Acid / Q000378:metabolism; D047488:Retinoid X Receptors; D013237:Stereoisomerism; D014157:Transcription Factors / Q000378:metabolism; D015533:Transcriptional Activation / Q000187:drug effects
chemical_list: D018168:Receptors, Retinoic Acid; D047488:Retinoid X Receptors; D014157:Transcription Factors; C087630:1,25-dihydroxy-16-ene-vitamin D3; D002117:Calcitriol