Changes in serum runt-related transcription factor 2 levels after a 6-month treatment with recombinant human parathyroid hormone in patients with osteoporosis

Background: The mechanisms regulating the anabolic response of the skeleton for recombinant human PTH (1-34) [rhPTH (1-34)] administration has not been fully elucidated. Aim: The aim of this study was to evaluate the effect of rhPTH (1-34) on serum levels of runt-related transcription factor 2 (Runx2) in women with osteoporosis. Methods: Sixty postmenopausal women with osteoporosis (EO group) and 45 control subjects (NC group) were enrolled in this study. The EO group received daily injection of 20 mu g rhPTH (1-34) plus oral 500 mg elemental calcium and 400 IU vitamin D3 for 6 months. Runx2 and Matrix metalloproteinase 13 (MMP-13) were measured with commercially available enzyme-linked immunosorbent assay kits. Bone mineral density (BMD) was also measured before and 6 months after rhPTH (1-34) treatment. Results: Serum total Ca2+, phosphate, and bone-specific alkaline phosphatase were significantly increased (p<0.05 or p<0.01), and the lumbar spine BMD (LS-BMD) was also increased by 4% in patients with osteoporosis after treatment with rhPTH (1-34) (p<0.05). On the contrary, serum Runx2 and MMP-13 were significantly decreased at post treatment (13.1% and 36.6%, respectively, p<0.05 and p<0.01). At baseline, serum Runx2 positively correlated with MMP-13 (r=0.74, p<0.01), the correction remained after adjusting for age and body mass index. Conclusion: The daily injection of rhPTH (1-34) was able to stimulate bone formation. The therapy of 20 mu g rhPTH (1-34) for 6 months resulted in decrease of serum Runx2 and MMP-13. These changes might reflect the increase of active osteoblasts and the better bone homeostasis. (J. Endocrinol. Invest. 35: 602-606, 2012) (C) 2012, Editrice Kurtis