Regulation of HOXA-10 and its expression in normal and abnormal endometrium

HOXA-10 is a member of a family of genes that serve as transcription factor s during development and have been shown to be important for uterine functi on. Using immunohistochemistry and RNAse protection assays (RPA), HOXA-10 w as shown to be expressed in both epithelial and stromal cells with increase d expression during the window of implantation. By in-vitro culture of isol ated endometrial epithelium or stroma, HOXA-10, expression was increased af ter treatment with oestradiol (10(-8) mol/l) with or without progesterone ( 10(-6) mol/l). In stromal cells, oestradiol and progesterone both appeared to increase HOXA-10 expression and were additive. Relaxin (30 ng/ml) appear ed to further increase stromal HOXA-10 expression. HOXA-10 expression durin g the window of implantation was compared in normal menstrual cycles to end ometrium from women with endometriosis and suspected defects in uterine rec eptivity. Little or no difference was seen in luminal, glandular or endothe lial HOXA-10 expression but a significant reduction in stroma HOXA-10 expre ssion was noted in women with endometriosis. In conclusion, HOXA-10 is a ho rmone-regulated endometrial transcription factor that appears to be respons ive to both ovarian steroids and relaxin. The appearance of this nuclear pr otein during the window of implantation in epithelium and stroma may offer new insight into the regulation of uterine receptivity and assist in the id entification of other genes that are critical to the establishment of a suc cessful pregnancy.