Sex specific response of cultured human bone cells to ERα and ERβ specific agonists by modulation of cell proliferation and creatine kinase specific activity.

We have previously reported that human cultured bone cells (hObs) respond to estradiol-17β (E2) by stimulating DNA synthesis, creatine kinase BB specific activity (CK) and other parameters sex-specifically. We now investigate the sex specificity of the response of these hObs to estrogen receptor (ER) α and ERβ specific agonists. Real time PCR revealed that all cells express mRNA for both ERs. ERα mRNA but not ERβ mRNA was stimulated by all estrogenic compounds in both pre- and post-menopausal hObs with no effect in male hObs. Cells treated with E2, 2,3-bis (4-hydroxyphenyl)-propionitrile (DPN; ERβ specific agonist) and 4,4',4″-[4-propyl-(1H)-pyrazol-1,3,5-triyl] tris-phenol (PPT; ERα specific agonist) showed increased DNA synthesis and CK in all female but not male hObs. Raloxifene (Ral), a specific ERα antagonist, inhibited the stimulation of DNA synthesis and CK by E2 or PPT, but not by DPN. DPN and PPT like E2 modulated the expression of both 12 and 15 lipooxygenase (LO) mRNA in both female but not male hObs. 12 and 15 HETE production was modulated only by DPN and PPT in these cells. The LO inhibitor baicaleine inhibited only E2 and PPT but not DPN effects in both female hObs. In conclusion, we provide herein evidence for the separation of age- and sex-dependent mediation via both ERα and ERβ pathways in the effects of estrogens on hObs, with a yet unknown mechanism.