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.