Different mechanisms for the induction of copper-zinc superoxide dismutase and manganese superoxide dismutase by progesterone in human endometrial stromal cells

BACKGROUND: The present study was undertaken to investigate the cAMP-dependent regulation of copper-zinc superoxide dismutase (Cu,Zn-SOD) and manganese SOD (Mn-SOD) by ovarian steroids in human endometrial stromal cells (ESC). METHODS and RESULTS: To examine the effect of cAMP on SOD expression, ESC were incubated with dibutyryl-cAMP (db-cAMP, 0.5 mmol/l), forskolin (25 mumol/l), or estradiol (E-2, 10(-8) mol/l) + medroxyprogesterone acetate (MPA, 10(-6) mol/l), for 18 days. E-2 + MPA significantly increased Cu,Zn-SOD activity and mRNA concentrations, whereas db-cAMP and forskolin had no effect. On the other hand, Mn-SOD activity and mRNA concentration were significantly increased by all of these treatments. Insulin-like growth factor-binding protein-1, a marker of decidualization, was clearly induced by db-cAMP, forskolin or E-2 + MPA, accompanied by morphological changes characteristic of decidualization. To study whether the increase in Mn-SOD by db-cAMP or E-2 + MPA was mediated by cAMP-dependent protein kinase A (PKA), ESC were incubated with protein kinase inhibitor (PKI) (10 mug/ml), an inhibitor of PKA, in the presence of db-cAMP or E-2 + MPA. The increase in Mn-SOD activity following db-cAMP or E-2 + MPA was completely inhibited by PKI. CONCLUSIONS: In the process of decidualization, E-2 + MPA increases Mn-SOD expression via a cAMP-dependent pathway. Cu,Zn-SOD is also up-regulated by E-2 + MPA, but via a different pathway from that involving cAMP.