Selective estradiol sensitivity in 12Z human endometriotic epithelial cell line

Estradiol (E2) is a potent estrogen molecule that plays a crucial role in regulating numerous healthy and pathophysiological processes. To model estrogen-dependent cellular activities in vitro in a physiologically meaningful way, cells chosen for experimentation should exhibit sensitivity to E2. The 12Z human endometriotic epithelial cell line is gaining attention as a model for estrogen-dependent conditions, but its functional responsiveness to E2 has not been well characterized. In the following study, we found that E2 does not influence 12Z proliferation, collective migration, or single-cell migration. However, 12Zs were selectively responsive to E2 in 3D migration models where the cells were physically confined. Upregulating ER, the primary mediator of estrogenic action, in the 12Zs did not enhance their functional E2 sensitivity. To delineate the underpinning of these behaviors, RNA sequencing was performed and revealed a differential expression of pseudogenes and non-coding RNAs in E2-treated 12Zs compared to vehicle control-treated 12Zs. Several signal transduction genes were significantly downregulated in ESR1-overexpressing 12Zs compared to normal 12Zs, which may play a role in their persistent lack of E2 sensitivity. These results prompt us to question whether the 12Z cell line, which mostly lacks functional E2 responsiveness, should be used in vitro as a model of estrogen-dependent processes and conditions.