Calcium-transport in quiescent and 1,25-dihydroxycholecalciferol-stimulated human osteosarcoma cells. Role in 24 hydroxylase enhancement.
The present study evaluates in osteosarcoma cells, the effects of a calcium channel inhibitor nicardipine in 24-hydroxylase activity and 45Ca desaturation curve in presence of 1,25-dihydroxycholecalciferol (1,25(OH)2D3). This sterol induced an increase in 24-OHase activity and 45Ca fluxes. Nicardipine reversed the effect of 1,25(OH)2D3 on 45Ca fluxes but reinforced the enhancement of the 24-OHase activity. The fact that the effects of 1,25(OH)2D3 were reduced by cycloheximide support the hypothesis of a de novo protein synthesis. Our study has allowed us to dissociate the effects of 1,25(OH)2D3 on 24-OHase enhancement from those on Ca2+ transport.
Rebut-Bonneton
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INSERM, Paris, France.
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Cancela
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D002117:Calcitriol / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D003513:Cycloheximide / Q000494:pharmacology; D003577:Cytochrome P-450 Enzyme System; D006801:Humans; D009529:Nicardipine / Q000494:pharmacology; D012516:Osteosarcoma; D014176:Protein Biosynthesis; D011506:Proteins / Q000037:antagonists & inhibitors; D013250:Steroid Hydroxylases / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D065668:Vitamin D3 24-Hydroxylase
D011506:Proteins; D003577:Cytochrome P-450 Enzyme System; D003513:Cycloheximide; D009529:Nicardipine; D013250:Steroid Hydroxylases; D065668:Vitamin D3 24-Hydroxylase; D002117:Calcitriol; D002118:Calcium