Effect Of Progesterone On HOXA11 Expression Of Endometrial Epithelial Cells Primary Cultured With Stromal Cells Culture Medium

Homeobox genes give identity of developing body segment and embryonic anteroposterior patterning in vertebrates, which is, a family of regulatory genes controlling embryonic development and cell differentiation, contain a common 180-nucleotic sequence homeobox and code for specific nuclear proteins (homeoproteins) that act as transcription factors. The homeobox sequence itself encodes a 60-amino-acid domain (the homeodomain), responsible for recognition and binding of sequence specific DNA motifs. Recent investigation indicates that Hoxa11, one of the homeobox genes, plays an essential role in endometrial development and implantation of mice. However, the function of HOXA11 in human endometrium is poorly understood. Several researches lately demonstrate that HOXA11 gene expresses periodically in normal endometrium, involved in the uterus developing and the embryo implanting .It's highly focused on how HOXA11 gene is regulated by estrogen and progesterone in the human menstrual cycle. Some studies revealed that progesterone down-regulated the expression of HOXA11 gene in human endometrial epithelial in the mid-secretory phrase (midluteal), in which is the peak time of progesterone secreted. But in vitro, progesterone stimulates HOXA11 gene expression in endometrial epithelial cells in human. So we suggest that stromal cells may take part in the process when HOXA11 gene expression was down-regulated by progesterone in endometrial epithelial cells in vivo. As we known, progesterone plays its role by combining with progesterone –receptor (PR). In this study, we have examined the effect of progesterone and mifepristone (RU486, a progesterone antagonist) on HOXA11 gene expression in human endometrial epithelium with stromal cells culture medium (SCM), and have investigated the alteration of HOXA11 gene in different time (the fourth hours, the twenty-four hours ). The stromal cells were cultured with the treatment of progesterone or progesterone before mifepristone (RU486) added, then the stromal cells culture medium (SCM) was collected. The endometrial epithelial cells were incubated with SCM at concentrations of 30% for 4 hours and 24 hours, and total RNA was isolated from epithelial cells for semi-quantitative RT-PCR.It was found that in vitro, progesterone diminished HOXA11 gene expression in endometrial epithelium that was incubated in minimum essential medium (MEM) with 30% SCM treated with progesterone for 4 hours and 24 hours. But this change disappeared after adding RU486 before the treatment of progesterone in endometrial epithelial cells. On the contrary, HOXA11 gene expression was stimulated by progesterone in the epithelial cells, which was incubated for 24 hours in MEM with 30% SCM that had been added RU486 before treatment with progesterone. Moreover, adding RU486 before progesterone in endometrial epithelium, it was unchangeable that HOXA11 gene expressed in endometrial epithelial cells which were incubated for 24 hours in MEM, diluted with 30% SCM treated by RU486 and progesterone.We can conclude that stromal cells was necessary in the process when progesterone down-regulated the expression of HOXA11 gene in endometrial epithelial in midluteal. Meanwhile, the effect of progesterone on HOXA11 gene expression was mediated by PR both in the stromal and epithelial cells. We believe that there must be some factors secreted by the stromal cells, which influenced the effect of progesterone on the endometrial epithelial. The result will be based on to establish molecular mechanism of sex steroids regulating HOXA11 gene expression in human endometrium. Furthermore, it may be useful to increase implantation and pregnancy rates, to diminish spontaneous abortion and to treat aberrant growth, differentiation and cancer of endometrium by altering HOXA11 gene expression.