Metabolism of 26,27-hexafluoro-1α,25-dihydroxyvitamin D3 and 26,27-hexafluoro1α,23(S)25-trihydroxyvitamin D3 in ROS17/2.8 cells transfected with a plasmid expressing CYP24

Abstract

1. To clarify the possibility that the metabolism of 26,27-hexafl uoro-1α, 25-dihydroxyvitamin D3 [F6-1,25(OH)2D3] to 26,27-hexafluoro-1α,23(S),25-trihydroxyvitamin D3 [F6-1,23,25(OH)3D3 and that of F6-1,23,25(OH)3D3 to 26,27-hexafluoro-23-oxo-1α,25-dihydroxyvitamin D3 [F6-23-oxo-1,25(OH)2D3] are catalysed by 25-hydroxyvitamin D 24-hydroxylase (CYP24), ROS17}2.8 cells transfected with a plasmid expressing CYP24 [pSVL-CYP24–] and a corresponding blank plasmid [pSLVCYP24R(®)] were used. 2. Incubation of [1β-3H]-F-1,25(OH)2D3 for 2 and 5 days with ROS17}2.8 cells transfected with pSVL-CYP24– generated a metabolite that co-migrated with authentic F6 -1,23,25(OH)3D3 in both normal phase and reversed-phase HPLC systems. 3. Incubation of [1β-3H]-F6 -1,23,25(OH)3D3 for 5 days with pSVL-CYP24– - transfected ROS 17}2.8 cells generated a metabolite that co-migrated with authentic F6 -23-oxo-1,25(OH)2D3. In contrast, the metabolites F6 -1,23,25(OH)3D3 or F6 -23-oxo- 1,25(OH)2D3 were not generated in the cells transfected with pSVL-CYP24R(-). 4. The results indicate that CYP24 catalyses the conversion of F6 -1,25(OH)2D3 to F6 -1,23,25(OH)3D3 and that of F6 -1,23,25(OH)3D3 to F6 -23-oxo-1,25(OH)2D3.