Abstract A052: DNMT1 inhibition suppresses EMT-driven invasion and migration in docetaxel-resistant prostate cancer

Abstract Background: Metastatic castration-resistant prostate cancer (mCRPC) carries poor prognosis due to androgen- and chemotherapy-resistance. Nearly half of patients develop resistance to docetaxel (DR), underscoring the need for new strategies. Aberrant DNA methylation contributes to drug resistance through gene silencing. We investigated whether DNMT1 inhibition via 5-Azacytidine (5-AZA) could attenuate crucial process in epithelial-to-mesenchymal (EMT) such as invasion and migration of DR prostate cancer (PCa) cells. Methods: Parental and docetaxel-resistant PC3 cells were treated with 5-AZA (0.5–16 µM, 72 h). Viability was measured by MTT. Protein markers (AR, ARv7, MDR1, GSTP1, DNMT1) were assessed by Western blot; invasion and migration by Matrigel and wound-healing assays; and EMT markers (CDH1, SNAI2, VIM) by RT-PCR. Results: 5-AZA reduced viability in a dose-dependent manner in both cell types. From these results, non-toxic concentrations of 5-AZA (1 and 2 µM) were selected for further experiments. DNMT1 inhibition and GSTP1 re-expression were successfully achieved, confirming global DNA hypomethylation. Invasion of PC3-DR cells was reduced by ∼90% versus untreated controls and by ∼40% compared with 5-AZA-treated parental cells (1 µM: p