Expression of the uteroglobin promoter in epithelial cell lines from endometrium

To understand the molecular mechanism of endometrial differentiation we have initiated an analysis of the uteroglobin promoter. Uteroglobin is normally expressed in endometrial tissues under the control of ovarian hormones. In gene transfer experiments with the Ishikawa cell line, derived from a human endometrial adenocarcinoma, we have identified several regions in the promoter of the uteroglobin gene that are responsible for its endometrium-specific expression. To evaluate the generality of these findings, we have begun cloning the promoter regions of potential endometrial markers, including the rat, mouse, and human uteroglobin gene. In the rat, expression of the uteroglobin-like gene, CC10, is dominant in the lung but is also observed in the endometrium of progesterone treated animals. A comparison of the 5'-flanking sequence of the rat and rabbit uteroglobin gene resulted in the detection of similarities and differences that could explain their differential expression in vivo. To substantiate these findings we have established several cell lines from rat endometrium using murine retroviral vectors containing a positive selection marker and various viral oncogenes, such as SV40 large T antigen, adenovirus E1A, and Ha-ras. Cell lines immortalized by SV40 T-antigen were subsequently transformed with the Ha-ras oncogene. Several cell lines exhibit properties of epithelial endometrial cells. Two cell lines generated with a temperature sensitive mutant of the SV40 large T-antigen grow as transformed cells at the permissive temperature, but differentiate upon shifting to the non-permissive temperature. These rat endometrial cell lines should be useful for the analysis of endometrium-specific gene expression and as model systems for endometrial carcinoma.