title: Effect of progesterone on apoptosis of murine MC3T3-E1 osteoblastic cells.
abstract: Progesterone (P) has been suggested as a bone-trophic hormone. Previous studies have shown that P promoted bone formation by stimulating the proliferation and differentiation of osteoblasts. But, the effect of P on apoptosis of osteoblast in vitro has not been reported. We propose that P may promote bone formation by suppressing the apoptosis of osteoblast. The present study was performed to investigate the effect of P on apoptosis of murine MC3T3-E1 osteoblastic cells. Cell apoptosis was measured by acidine orange/ethidium bromide (AO/EB) staining and sandwich-enzyme-immunoassay. Progesterone receptor (PR), cytochrome c, caspase-9 and caspase-3 protein levels were determined by Western blot analysis. The enzyme substrate was also used to assess the activation of caspase-3 and caspase-9. Progesterone suppressed MC3T3-E1 cells apoptosis induced by serum deprivation, and this effect was blocked by a PR antagonist RU486. Furthermore, the suppressive effects of P on cytochrome c release and caspase-9 and caspase-3 activation in serum-deprived MC3T3-E1 cells were also reversed by RU486. Our study demonstrated that P protects osteoblast against apoptosis through PR and the downstream mitochondrial pathway. Thus, the data suggest that the effects of P on osteoblast apoptosis may contribute to the mechanisms by which P exerts its action on bone formation.
authors.affiliation: Department of Clinical Laboratory, The Third Affiliated Hospital, Suzhou University, 213003, Changzhou, Jiangsu, China.
authors.forename: Qing-Ping
authors.initials: QP
authors.lastname: Wang
authors.forename: Hui
authors.initials: H
authors.lastname: Xie
authors.forename: Ling-Qing
authors.initials: LQ
authors.lastname: Yuan
authors.forename: Xiang-Hang
authors.initials: XH
authors.lastname: Luo
authors.forename: Hui
authors.initials: H
authors.lastname: Li
authors.forename: Dan
authors.initials: D
authors.lastname: Wang
authors.forename: Ping
authors.initials: P
authors.lastname: Meng
authors.forename: Er-Yuan
authors.initials: EY
authors.lastname: Liao
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D002460:Cell Line; D016895:Culture Media, Serum-Free; D051379:Mice; D010006:Osteoblasts / Q000166:cytology* / Q000187:drug effects*; D011374:Progesterone / Q000494:pharmacology*; D020033:Protein Isoforms / Q000378:metabolism; D011980:Receptors, Progesterone / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D016895:Culture Media, Serum-Free; D020033:Protein Isoforms; D011980:Receptors, Progesterone; D011374:Progesterone; D053148:Caspase 3; D053453:Caspase 9