CONICET | Buscador de Institutos y Recursos Humanos

The Forkhead Box factors (FOX) belong to a family of over 40 proteins that regulate genes related to: cell growth, proliferation, differentiation, and migration. FOXA1 and FOXM1 have been reported to be cofactors of the androgen and glucocorticoid receptors (AR and GR), which are involved in prostate carcinogenesis. We aim to study the role of FOXA1 and FOXM1 in prostate cancer (PCa). We down-regulated FOXA1 and FOXM1 expression through transfection with shRNA in PC3 (AR-, GR+) and C4-2B (AR+, GR+) PCa cell lines. We previously showed that FOXA1 and FOXM1 down-regulation reduced cell proliferation (by MTS assay), altered cell morphology and modulated the transcriptional activity of GR. In this work, we further evaluated the role of these factors in PCa. Using a wound healing assay, we observed that the down-regulation of FOXA1 reduced cell migration in both cell lines (remaining wound area at 24 h >40% compared to control; p=0.02). Similar results were observed for the down-regulation of FOXM1; however, it was only significant for C4-2B cells (35%, p=0.02). We found a significant reduction in cell migration when both genes were down-regulated simultaneously (45%, p=0.001 for PC3 and 50%, p=0.003 for C4-2B). Analysis of cell cycle using propidium iodide staining and flow cytometry revealed that the down-regulation of FOXA1 produced a 10% increased of cells in S-phase in both cell lines, and a decreased in G1-phase (7% for PC3 and 15% for C4-2B). Similar results were observe when FOXM1 was down-regulated alone or together with FOXA1 (S-phase increase 5% for both cell lines). Interestingly, the double knocked-down cells showed a 5% increase in sub-G1 (apoptotic) cells. In conclusion, we demonstrated that FOXA1 and FOXM1 are involved in PCa cell migration and cell cycle progression. These results give new insights in the PCa biology and provide new potential therapeutic targets.