Carboxyl-terminal parathyroid hormone peptide (53–84) elevates alkaline phosphatase and osteocalcin mRNA levels in SaOS-2 cells

Authors

  • Dr. M. Kung Sutherland,

    Corresponding author
    1. Division of Endocrinology and Metabolism, St. Michael's Hospital, and Department of Medicine, University of Toronto, Toronto, Ontario, Canada
    • Calcium Research Laboratory St. Michael's Hospital Annex 38 Shuter Street Toronto, Ontario, Canada M5B 1A6
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  • L.G. Rao,

    1. Division of Endocrinology and Metabolism, St. Michael's Hospital, and Department of Medicine, University of Toronto, Toronto, Ontario, Canada
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  • J.N. Wylie,

    1. Division of Endocrinology and Metabolism, St. Michael's Hospital, and Department of Medicine, University of Toronto, Toronto, Ontario, Canada
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  • A. Gupta,

    1. MRC Group in Periodontal Physiology, University of Toronto, Toronto, Ontario, Canada
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  • H. Ly,

    1. Division of Endocrinology and Metabolism, St. Michael's Hospital, and Department of Medicine, University of Toronto, Toronto, Ontario, Canada
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  • J. Sodek,

    1. MRC Group in Periodontal Physiology, University of Toronto, Toronto, Ontario, Canada
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  • T.M. Murray

    1. Division of Endocrinology and Metabolism, St. Michael's Hospital, and Department of Medicine, University of Toronto, Toronto, Ontario, Canada
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Abstract

Previous findings in our laboratory have shown that hPTH-(53–84) stimulates alkaline phosphatase activity in dexamethasone-treated ROS 17/2.8 cells. In the present study, we examined the effects of hPTH-(53–84) and hPTH-(1–34) on the expressions of alkaline phosphatase, osteocalcin, and collagen type I mRNA levels in the human osteosarcoma cell line SaOS-2. The effect of hPTH-(53–84) on alkaline phosphatase and osteocalcin message levels was dose dependent (ANOVA, p < 0.005 and p < 0.001, respectively), with significant stimulation observed at 10 nM. Treatment with 10 nM hPTH-(53–84) for 24 h resulted in significant 2- and 1.4-fold increases in mRNA levels for alkaline phosphatase and osteocalcin, respectively (p < 0.05), but had no effect on collagen type I expression. The increased alkaline phosphatase mRNA levels was associated with a 1.5-fold increase in enzyme activity (p < 0.05). In contrast, under similar incubation conditions, hPTH-(1–34) had no significant effects on alkaline phosphatase or osteocalcin mRNA levels. On the other hand, hPTH-(1–34) had dose-dependent stimulatory effects on collagen type I mRNA levels (ANOVA, p < 0.001), 10 nM hPTH-(1–34) stimulating collagen type I expression 1.6-fold (p < 0.05). The results indicate that carboxyl-terminal hPTH-(53–84) has direct and unique biologic effects in human osteoblast-like cells in culture.

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