Progesterone Receptor Subcellular Localization and Gene Expression Profile in Human Astrocytoma Cells Are Modified by Progesterone

Intracellular progesterone receptor (PR) has been identified in human astrocytomas, the most common and aggressive primary brain tumors in humans. It has been reported that PR cell distribution affects their transcriptional activity and turnover. In this work we studied by immunofluorescence the effects of estradiol and progesterone on the subcellular localization of PR in a grade III human astrocytoma derived cell line (U373). We observed that total PR was mainly distributed in the cytoplasm without hormonal treatment. Estradiol (10 nM) increased PR presence in the cytoplasm of U373 cells, whereas progesterone (10 nM) and RU486 (PR antagonist, 1 µM) blocked this effect. To investigate the role of PR activity in the regulation of gene expression pattern of U373 cells, we evaluated by microarray analysis the profile of genes regulated by progesterone, RU486, or both steroids. We found different genes regulated by steroid treatments that encode for proteins involved in metabolism, transport, cell cycle, proliferation, metastasis, apoptosis, processing of nucleic acids and proteins, adhesion, pathogenesis, immune response, cytoskeleton, and membrane receptors. We determined that 30 genes were regulated by progesterone, 41 genes by RU486 alone, and 13 genes by the cotreatment of progesterone+RU486, suggesting that there are many genes regulated by intracellular PR or through other signaling pathways modulated by progesterone. All these data suggest that PR distribution and activity should modify astrocytomas growth.