Effect of HO1 induction on glucocorticoid receptor in a prostate cancer cell line

LEONARDI DAIANA; PAEZ ALEJANDRA; SCHUSTER FEDERICO; ANSELMINO NICOLAS; BRANDANI JAVIER; ABBATE MERCEDES; GUERON GERALDINE; COTIGNOLA JAVIER; VAZQUEZ ELBA

Philadelphia

Congreso; American Association for Cancer Research (AACR) annual meeting 2015; 2015

AACR

In order to offset the toxicity of chemotherapy, glucocorticoids have long been used in the treatment of advanced-stage prostate cancer. Nevertheless, nowadays many authors report that the glucocorticoid receptor (GR) can substitute the androgen receptor and activate a similar but distinguishable set of genes. Our aim is to study GR signaling and the effect of heme oxygenase 1 (HO1) in prostate cancer cell lines. We tested three dexamethasone (Dex) concentrations (10-7 M, 10-8 M y 10-9 M) for 24 hours on PC3 cells and found out no differences in cell viability. In order to study GR transcriptional activity PC3 cells were transfected with a glucocorticoid response element promoter-driven luciferase expression plasmid, and were treated either with hemin (HO1 inductor, 80μM, 24h), Dex (10-8 M, 6h) or both drugs. In all the cases the cells were cultured in medium with charcoal-dextran treated serum. Hemin significantly reduced the GR basal activity (p=0.03) as well as the Dex induced activity (p=0.01). These results were confirmed by RTqPCR with a well known GR target, IkB, and a NFkB luciferase reporter assay. Using confocal fluorescence microscopy, we confirmed GR nuclear translocation upon Dex treatment, and showed a lower translocation phenomenon when cells were exposed to the combined effect of hemin and Dex. These results agree with the diminished luciferase activity of the MMTV-luc in the presence of hemin+Dex vs. Dex. By co immunoprecipitation we showed physical interaction between GR and HO1 in nucleus and cytoplasm. In conclusion, these results suggest that HO1 induction modulates GR activity and it sub cellular localization in PC3 cell line.