Relative potencies of 1,25-(OH)2D3 and 19-Nor-1,25-(OH)2D2 on inducing differentiation and markers of bone formation in MG-63 cells
19-Nor-1,25-(OH) 2 D 2 , an analog of 1,25-(OH) 2 D 3 , is used to treat secondary hyperparathyroidism because it suppresses parathyroid hormone synthesis and secretion with lower calcemic and phosphatemic activities. 19-Nor-1,25-(OH) 2 D 2 is approximately 10 times less active than 1,25-(OH) 2 D 3...
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Published in | Journal of the American Society of Nephrology Vol. 12; no. 7; pp. 1468 - 1474 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
Hagerstown, MD
Lippincott Williams & Wilkins
01.07.2001
|
Subjects | |
Online Access | Get full text |
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Summary: | 19-Nor-1,25-(OH)
2
D
2
, an analog of 1,25-(OH)
2
D
3
, is used to treat secondary hyperparathyroidism because it suppresses parathyroid hormone synthesis and secretion with lower calcemic and phosphatemic activities. 19-Nor-1,25-(OH)
2
D
2
is approximately 10 times less active than 1,25-(OH)
2
D
3
in promoting bone resorption, which accounts in part for the low potency of this analog in increasing serum calcium and phosphorus. Concern that 19-nor-1,25-(OH)
2
D
2
also could be less potent than 1,25-(OH)
2
D
3
on bone formation led to a comparison of the potency of both compounds on osteoblasts. In the human osteoblast-like cell line MG-63, 1,25-(OH)
2
D
3
and 19-nor-1,25-(OH)
2
D
2
had a similar potency in upregulating vitamin D receptor content and suppressing proliferation. Both sterols caused a similar reduction in DNA content and proliferating cell nuclear antigen protein expression. Time-course and dose-response studies on 1,25-(OH)
2
D
3
and 19-nor-1,25-(OH)
2
D
2
induction of the marker of bone formation, osteocalcin, showed overlapping curves. The effects on alkaline phosphatase (ALP) activity also were studied in MG-63 cells that had been co-treated with either sterol and transforming growth factor-β, an enhancer of 1,25-(OH)
2
D
3
—induced ALP activity in this cell line. Transforming growth factor-β alone had no effect, whereas 1,25-(OH)
2
D
3
and 19-nor-1,25-(OH)
2
D
2
increased ALP activity similarly. These studies demonstrate that 19-nor-1,25-(OH)
2
D
2
has the same potency as 1,25-(OH)
2
D
3
not only in inducing vitamin D receptor content, osteocalcin levels, and ALP activity but also in controlling osteoblastic growth. Therefore, it is unlikely that 19-nor-1,25-(OH)
2
D
2
would have deleterious effects on bone remodeling. |
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ISSN: | 1046-6673 1533-3450 |
DOI: | 10.1681/ASN.V1271468 |