Sex steroids mediate HOXA11 expression in the human peri-implantation endometrium

Under the influence of sex steroids, human endometrium undergoes sequential development in preparation for implantation. Hoxa11 is essential for impla ntation in the mouse. Here we describe a potential role for HOXA11 in human endometrial development and implantation. Northern analysis demonstrates t hat HOXA11 is expressed in a menstrual cycle phase-dependent fashion in adu lt human endometrium. HOXA11 messenger RNA levels dramatically increase at the time of implantation and remain increased in pregnancy. In vitro, HOXA1 1 expression is increased in response to estrogen or progesterone. There is a dose-responsive increase over the physiologic range of progesterone conc entration. Pretreatment with Cyclohexamide does not decrease the response t o estrogen. Steroids are novel regulators HOX gene expression. The spatial and temporal pattern of HOXA11 expression in the human endometrium suggests a role in endometrial development, implantation, and maintenance of pregna ncy.