[DHEA inhibits apoptosis of murine OB through MAPK signaling pathways independent of either ARs or ERs].
Dehydroepiandrosterone (DHEA) is a promising agent for the treatment of post-menopausal osteoporosis (PMO), but the molecular mechanisms and signaling pathways by which this steroid modulates apoptosis of osteoblasts (OB) are still poorly understood. In this study,the OBs were cultured in vitro by the enzyme-digested method,treated with DHEA (10(-7) mol/L) for 0h, 24h, 48h, 72h, respectively. The expressions of ER alpha, ER beta and AR mRNA in OB were analyzed by RT-PCR. After the primary OBs were deprived of serum for a further 24h, and then pretreated with 1 micromol/L ICI 182,780 (an estrogen receptor antagonist), 10 micromol/L Flutamide (an androgen receptor antagonist) or 100 micromol/L U0126 (a specific inhibitor of MAPK pathway) for 1h, they were treated with a series of concentrations of DHEA (10(-10) - 10(-5) mol/L) in serum-free medium for 72h,the apoptotic cells were analyzed by FCM with the Annexin-V-FITC/PI dual labeling technique. The OBs were incubated in 1 micromol/L ICI 182,780 or 10 micromol/L Flutamide for 25 minutes,and then treated with different concentrations of DHEA for the further 10 minutes. The phosphorylation status of ERK1/2 was analyzed by Western blot. After the OBs were incubated with DHEA (10(-7)mol/L) for 24h, 48h or 72h, respectively, its ERbeta and AR mRNA level were increased (P<0.05, P<0.01, respectively), but the ER alpha mRNA level had no change. The 10(-9) - 10(-6) mol/L of DHEA inhibited OBs early apoptosis induced by the serum deprivation (P<0.05, P<0.01, respectively). The inhibiting effect, moreover, could be blocked by the specific inhibitor of MAPK pathway, U0126. The effects of DHEA were neither blocked by the steroid hormone antagonist ICI 182,780 nor by Flutamide. Western blot showed that neither receptor antagonist ICI 182,780 nor Flutamide could block the DHEA-induced ERKs phosphorylation in OBs,which was similar to the apoptosis. DHEA inhibits apoptosis in OBs presumably via a DHEA-specific receptor that involves mitogen activated protein kinase (MAPK) signal pathway, phospho-pERK1/2, independent of either ARs or ERs.
Wang
Ling
L
Laboratory for Reproductive Immunology, Hospital and Institute of Obstetrics & Gynecology, Shanghai Medical college, Fudan University, Shanghai 200011.
Li
Da Jin
DJ
Wang
Wen Jun
WJ
Zhu
Ying
Y
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002070:Butadienes / Q000494:pharmacology; D002478:Cells, Cultured; D003687:Dehydroepiandrosterone / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D047628:Estrogen Receptor alpha / Q000235:genetics; D047629:Estrogen Receptor beta / Q000235:genetics; D005260:Female; D015870:Gene Expression / Q000187:drug effects; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D009570:Nitriles / Q000494:pharmacology; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011944:Receptors, Androgen / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction
D002070:Butadienes; D004791:Enzyme Inhibitors; D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D009570:Nitriles; D011944:Receptors, Androgen; C113580:U 0126; D003687:Dehydroepiandrosterone; D020928:Mitogen-Activated Protein Kinases