Differentiation and uteroglobin gene expression by novel rabbit endometrial cell lines.

A clear understanding of the mechanism of differentiation of mammalian endometrial epithelia would significantly improve our knowledge of embryo implantation and placentation. An ideal model for such studies would be immortal endometrial epithelial cell lines which express a well characterized, steroid-responsive, differentiation-specific gene in vitro. We characterized two cell lines which are temperature-sensitive for differentiation. At the non-permissive temperature (39.5 degrees C), in presence of ovarian steroids, these cells express the gene coding for uteroglobin, a steroid-dependent, immunomodulatory/antiinflammatory protein in the rabbit. In addition, when cultured on artificial basement membrane (Matrigel), in presence of ovarian steroids both cell lines developed organized, tubular structures with lumens, reminiscent of an intact endometrium and secreted 33-fold more uteroglobin than the untreated controls. Thus, these immortal cell lines provide a unique model to study endometrial epithelial cell differentiation and steroid hormone action in vitro.