Progesterone-Induced Inhibition of Growth and Differential Regulation of Gene Expression in PRA- and/or PRB-Expressing Endometrial Cancer Cell Lines:

Objective: Progesterone plays an important role in controlling proliferation and diferentiation of the human endometrium. Because there are two progesterone receptor isoforms (PRA and PRB), it was important to generate tools to be able to study the role of these two progesterone receptors separately.Methods: Using stable transfection techniques, both human progesterone receptor isoforms (hPRA and hPRB) were reintroduced into a hPR-negative subclone of the well-differentiated endometrial cancer cell line Ishikawa. Several Ishikawa subcell lines were constructed, each expressing different levels of hPRA, hPRB, or hPRA and hPRB, respectively.Results: These Ishikawa subcell lines showed a marked progesterone-induced growth inhibition with induction of apoptosis after long-term culture in the presence of hormone. Upon measuring gene regulation, a clear diference in regulation of expression of the selected genes by progesterone treatment was observed between the PRA-, PRB-, or PRA/B-expressing cell lines. Integ...