MVLN cells: a bioluminescent MCE-7-derived cell line to study the modulation of estrogenic activity.

We previously established a stable expression system in MCF-7 cells for the detection of (anti)estrogenic activity by assaying the reporter enzyme activity of firefly luciferase. In this cell line (called MVLN), the bioluminescent response can be measured either in the cellular homogenate, or in intact living cells. Here we present various potential experimental uses of this cellular model. First, we used this cell line to screen natural or synthetic molecules classified as full or partial (anti)estrogens and observed that their behavior towards our model was identical to that expected. Moreover, the bioluminescent response was in agreement with the natural responses like cellular proliferation or stimulation of the progesterone receptor. We then demonstrated the inhibitory effects of retinoic acid and 1,25 dihydroxyvitamin D3, two molecules which do not compete with estradiol for its receptor. We thus deduced that with this cell line an "antiestrogenic" effect which occurred at any step of the estrogenic action, might be detected. Finally, we showed that detection of luciferase activity in intact living cells was particularly helpful for investigating the evolution of estrogenic activity. For instance, we observed that long-term treatment of MVLN cells with an antiestrogen irreversibly decreased the bioluminescent response by more than 90%. This phenomenon affected all cells equally and could not be reversed, even by long-term estradiol treatment. We therefore conclude that this chimeric response faithfully reflects estrogenic action in the cell and can be used to develop different aspects of the endocrine research.