Mutual interaction of special phytoestrogenic compounds, their synthetic carboxy-derivatives and the less-calcemic vitamin D analog activities in human derived female cultured osteoblasts

Cultured female-derived human bone cells (hObs) responded by different parameters to different phytoestrogenic and vitamin D compounds. Pre- and post-menopausal hObs express ERα and ERβ mRNA with higher abundance of ERα. Pre-treatment with the less-calcemic vitamin D analog JKF 1624F2-2 (JKF) upregulated responsiveness to estrogens via modulation of ERs expression. These estrogenic compounds induce the expression and activity of 25 hydroxy-vitamin D3-1α hydroxylase (1OHase). We now analyzed the effects of carboxy-genistein (cG), carboxy-biocainin A (cBA) and carboxy-daidzein (cD), of BA, D or G and of licorice derived compounds glabridin (Glb) and glabrene (Gla) and estradiol-17β (E2) on DNA synthesis, creatine kinase specific activity (CK), intracellular and membranal E2 binding and their modulations by JKF in hObs. We also analyzed modulation by phytoestrogenic compounds of 1OHase mRNA expression and activity. We showed that: (1) all compounds stimulated DNA synthesis and CK. (2) JKF and all estrogenic compounds modulated ERα and ERβ mRNA expression. (3) Pre-treatment with JKF increased DNA synthesis and CK responses only to E2, D, G and Gla. (4) JKF increased the intracellular competitive binding only of E2, D and G. (5) JKF abolished the membranal binding of all protein-bound estrogens. (6) JKF and all estrogenic compounds except the protein-bound ones up-regulated 1OHase expression and activity. In conclusion phytoestrogens and their analogs increase DNA synthesis and CK, and lead to increased production of 1,25(OH)2D3 in hObs, while pre-treatment with JKF modulates the effect of estrogenic compounds via regulation of ERs mRNA expression in a yet unclear mechanism.

► Phytoestrogenic compounds stimulated DNA synthesis and CK specific activity.
► JKF and all phytoestrogenic compounds modulated ERα and ERβ mRNA expression.
► Pre-treatment with JKF increased DNA synthesis and CK specific activity responses only to E2, D, G and Gla.
► JKF increased the intracellular competitive binding only of E2, D and G.
► JKF abolished the membranal binding of all protein-bound estrogens.
► JKF and all phytoestrogenic compounds except the protein-bound ones up-regulated 1OHase expression and activity.