Effect of progesterone on apoptosis of murine MC3T3-E1 osteoblastic cells.
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.
Wang
Qing-Ping
QP
Department of Clinical Laboratory, The Third Affiliated Hospital, Suzhou University, 213003, Changzhou, Jiangsu, China.
Xie
Hui
H
Yuan
Ling-Qing
LQ
Luo
Xiang-Hang
XH
Li
Hui
H
Wang
Dan
D
Meng
Ping
P
Liao
Er-Yuan
EY
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
D016895:Culture Media, Serum-Free; D020033:Protein Isoforms; D011980:Receptors, Progesterone; D011374:Progesterone; D053148:Caspase 3; D053453:Caspase 9