Mutual Modulation Of Femarelle And Vitamin D Analog Activities In Human Derived Female Cultured Osteoblasts

Introduction: Pre-, post-menopausal, and male human osteoblasts (hObs) express estradiol-17 beta(E-2) receptors alpha and beta (EX alpha and ER beta), vitamin D receptor (VDR), and 25-hydroxy vitamin D-3 1-alpha hydroxylase (1OHase) and produce 1,25 (OH)(2)D-3 (1,25D). Pre-treatment with JKF (JKF 1624F(2-2)) up-regulated estrogenic responsiveness, via modulation of ERs expression and E-2 binding. These estrogens induce VDR and 1OHase expression and 1,25D production. Purpose: Compared the effects of femarelle (F) to daidzein (D) and E-2 by themselves and their modulation by JKF. Methods: hObs derived from human bones at different ages and sex were cultured, treated with different hormones and analyzed for the different parameters. Results: (1) F, D and E-2 stimulated (3)[H] thymidine incorporation (DNA) and creatine kinase specific activity (CK) in female but not in male hObs. The responses to E-2 and to D unlike to F were up-regulated by JKF. (2) All hormones increased ER alpha and decreased ER beta mRNA in all hObs. (3) JKF modulated in different ways the expressions of ER alpha and ER beta mRNA in all hObs. (4) JKF did not significantly modulate the expressions of ER alpha and ER beta mRNA in all hObs. (5) JKF increased intracellular competitive binding of E-2 by all hormones only in female hObs. (6) Pre-treatment with all hormones increased VDR and 1OHase expression and 1,25D formation in pre- and post-, but only JKF modulated it in male hObs. Conclusions: F, D and E-2 increase different parameters in hObs. However, pre-treatment with JKF modulates the effect of E-2 and D but not of F. F reciprocally modulates mRNA expression and activity of 1OHase which in turn up-regulate ERs expression and activity. These finding may contribute to F's beneficial role in treatment of post-menopausal bone loss even in vitamin D deficiency.