Estrogen promotes the growth of decidual stromal cells in human early pregnancy

Interleukin-24 (IL-24) is a novel tumor suppressor gene, which has suppressor activity in a broad spectrum of human cancer cells. The present study aimed to elucidate the biological function of IL-24 and its receptors (IL-20R1, IL-20R2 and IL-22R1) in decidual stromal cells (DSCs) at human maternal- fetal interface. The DSCs behaviors in vitro were verified by viability (MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide) and apoptosis assay, respectively. Additionally, the effects of pregnancy-associated hormones on IL-24 and the effect of IL-24 on the correspondent functional molecules were investigated by ELISA, in-cell western and flow cytometry, respectively. Here we found that DSCs expressed IL-24 and its receptors, and IL-24 obviously suppressed the viability and stimulated the apoptosis in DSCs. On the contrary, both anti-IL-24 and IL-22R1 neutralizing antibodies markedly promoted growth and reduced the apoptosis. Estrogen but not progesterone could significantly decrease IL-24 but not its receptors, and these effects could be abolished by the antagonist of estrogen re- ceptor beta (ERb). IL-24 significantly restricted the stimulatory effect of estrogen on the viability, anti-apoptosis, anti-apoptosis gene Bcl-2 and proliferation relative gene Ki-67 in DSCs. Our study has demonstrated that IL-24/IL-20R2/IL-22R1 axis is involved in the regulation of estrogen/ERb signaling on the growth of DSCs through up-regulating the expression of Bcl-2 and Ki67, which suggests that estrogen plays an important role in DSC growth of the early pregnancy through down-regulating IL-24.