Effects of 1alpha,25-dihydroxy-16ene, 23yne-vitamin D3 on osteoblastic function in human osteosarcoma SaOS-2 cells: differentiation-stage dependence and modulation by 17-beta estradiol.
We compared the separate effects of 1alpha,25-dihydroxyvitamin D3 (1alpha,25(OH)2D3) and its analog, 1alpha,25-dihydroxy-16ene,23yne-vitamin D3 (1alpha25(OH)2-16ene,23yne-D3), as well as their interactions with 17-beta estradiol (E2) in our human osteosarcoma SaOS-2 cell models representing two stages of differentiation, the SaOS+DEX and SaOS-DEX cells. SaOS+DEX cells have been previously shown to express higher PTH-stimulated adenylate cyclase (PTH-AC) and basal alkaline phosphatase (ALP) activities compared with SaOS-DEX cells. ALP: In SaOS+DEX cells, 0.1 nmol/L analog, but not 1alpha,25(OH)2D3, increased ALP activity 1.7-fold (p < 0.05). Instead, 1 nmol/L 1alpha,25(OH)2D3 increased ALP 1.4-fold (p < 0.05). In these cells, E2 enhanced 1alpha,25(OH)2D3-stimulated ALP activity (ANOVA, F = 51.22, p <0.0001), while inhibiting the effect of the analog. [3H]-Thymidine uptake: In SaOS+DEX cells, 1alpha,25(OH)2D3 had biphasic effects (ANOVA, F = 13.08, p < 0.0001), which were not altered by E2. In contrast, the analog was stimulatory only with E2 (ANOVA, F = 3.59, p < 0.025). Osteocalcin (OC): 1alpha,25(OH)2D3 and its analog stimulated OC production in SaOS-DEX cells with smaller effects in SaOS+DEX cells. In SaOS-DEX cells, E2 enhanced the effect of 1alpha,25(OH)2D3, but not that of the analog. PTH-AC: In SaOS-DEX cells, 100 nmol/L analog inhibited PTH-AC activities by 50% (p < 0.01), whereas 1alpha,25(OH)2D3 had little effect. In SaOS+DEX cells, both compounds inhibited PTH-AC approximately 35%. E2 inhibited the effect of the analog in SaOS-DEX cells, but enhanced the effects of both compounds in SaOS+DEX cells. These results show that the analog 1alpha,25(OH)2-16ene,23yne-D3 was effective in regulating osteoblastic function; its effects were modulated by E2 and dependent upon the stage of osteoblast differentiation.
Rao
L G
LG
Calcium Research Lab., St. Michael's Hospital and Department of Medicine, University of Toronto, Ontario, Canada.
Sutherland
M K
MK
Reddy
G S
GS
Siu-Caldera
M L
ML
Uskokovic
M R
MR
Murray
T M
TM
D000262:Adenylyl Cyclases / Q000378:metabolism; D000469:Alkaline Phosphatase / Q000378:metabolism; D002117:Calcitriol / Q000031:analogs & derivatives* / Q000494:pharmacology; D002454:Cell Differentiation; D004100:Dihydroxycholecalciferols / Q000494:pharmacology*; D004958:Estradiol / Q000494:pharmacology*; D006801:Humans; D010006:Osteoblasts / Q000187:drug effects* / Q000378:metabolism; D015675:Osteocalcin / Q000096:biosynthesis / Q000187:drug effects; D012516:Osteosarcoma; D010281:Parathyroid Hormone / Q000494:pharmacology; D013936:Thymidine / Q000378:metabolism; D014407:Tumor Cells, Cultured
D004100:Dihydroxycholecalciferols; D010281:Parathyroid Hormone; D015675:Osteocalcin; D004958:Estradiol; C023850:1 alpha,24-dihydroxyvitamin D3; D000469:Alkaline Phosphatase; D000262:Adenylyl Cyclases; D002117:Calcitriol; C064183:Ro 23-7553; D013936:Thymidine