title: Potent antiproliferative effects of 25-hydroxy-16-ene-23-yne-vitamin D₃ that resists the catalytic activity of both CYP27B1 and CYP24A1.
abstract: The potency of 25-hydroxyvitamin D3 (25(OH)D3) is increased by several fold through its metabolism into 1α,25-dihydroxyvitamin D3 (1α,25(OH)2D3) by cytochrome P450 27B1 (CYP27B1). Thus, the pivotal role of 1α-hydroxylation in the activation of vitamin D compounds is well known. Here, we examined the metabolism of 25-hydroxy-16-ene-23-yne-vitamin D3 (25(OH)-16-ene-23-yne-D3), a synthetic analog of 25(OH)D3 in a cell-free system and demonstrated that 25(OH)-16-ene-23-yne-D3 is neither activated by CYP27B1 nor inactivated by cytochrome P450 24A1 (CYP24A1). These findings were also confirmed in immortalized normal human prostate epithelial cells (PZ-HPV-7) which are known to express both CYP27B1 and CYP24A1, indicating that the structural modifications featured in 25(OH)-16-ene-23-yne-D3 enable the analog to resist the actions of both CYP27B1 and CYP24A1. To provide intelligible structure-function information, we also performed molecular docking analysis between the analog and CYP27B1. Furthermore, 25(OH)-16-ene-23-yne-D3 was found to suppress the growth of PZ-HPV-7 cells with a potency equivalent to 1α,25(OH)2D3. The antiproliferative activity of 25(OH)-16-ene-23-yne-D3 was found to be vitamin D receptor (VDR)-dependent as it failed to inhibit the growth of mammary tumor cells derived from VDR-knockout mice. Furthermore, stable introduction of VDR into VDR-knockout cells restored the growth inhibition by 25(OH)-16-ene-23-yne-D3. Thus, we identified 25-hydroxy-16-ene-23-yne-vitamin D3 as a novel non-1α-hydroxylated vitamin D analog which is equipotent to 1α,25(OH)2D3 in its antiproliferative activity. We now propose that the low potency of the intrinsic VDR-mediated activities of 25(OH)D3 can be augmented to the level of 1α,25(OH)2D3 without its activation through 1α-hydroxylation by CYP27B1, but by simply preventing its inactivation by CYP24A1.
authors.affiliation: Epimer LLC, North Smithfield, Rhode Island, 02896, USA.
authors.forename: Steve Y
authors.initials: SY
authors.lastname: Rhieu
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Annalora
authors.forename: Erika
authors.initials: E
authors.lastname: LaPorta
authors.forename: JoEllen
authors.initials: J
authors.lastname: Welsh
authors.forename: Toshimasa
authors.initials: T
authors.lastname: Itoh
authors.forename: Keiko
authors.initials: K
authors.lastname: Yamamoto
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Sakaki
authors.forename: Tai C
authors.initials: TC
authors.lastname: Chen
authors.forename: Milan R
authors.initials: MR
authors.lastname: Uskokovic
authors.forename: G Satyanarayana
authors.initials: GS
authors.lastname: Reddy
mesh_terms: D015090:25-Hydroxyvitamin D3 1-alpha-Hydroxylase / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D002384:Catalysis; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002762:Cholecalciferol / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000737:chemistry; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D006801:Humans; D008297:Male; D051379:Mice; D062105:Molecular Docking Simulation; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D018167:Receptors, Calcitriol / Q000737:chemistry / Q000378:metabolism; D065668:Vitamin D3 24-Hydroxylase / Q000737:chemistry / Q000378:metabolism*
chemical_list: C116776:25-hydroxy-16,23-diene vitamin D3; D018167:Receptors, Calcitriol; D002762:Cholecalciferol; C585549:CYP24A1 protein, human; D065668:Vitamin D3 24-Hydroxylase; D015090:25-Hydroxyvitamin D3 1-alpha-Hydroxylase
keywords: 16-ene-23-yne; ANTIPROLIFERATIVE ACTIVITY; CYP24A1; CYP27B1; VITAMIN D