DNMT3A epigenetically regulates key microRNAs involved in epithelial-to-mesenchymal transition in prostate cancer.

Epithelial-to-Mesenchymal Transition (EMT) is involved in prostate cancer metastatic progression, and its plasticity suggests epigenetic implications. Deregulation of DNMTs and several miRNAs plays a relevant role in EMT, but their interplay has not been clarified yet. In this study we provide evidence that DNMT3A interaction with several miRNAs has a central role in an ex-vivo EMT prostate cancer model obtained via exposure of PC3 cells to conditioned media from cancer-associated fibroblasts (CM-CAFs). The analysis of the alterations of the miRNA profile shows that miR-200 family (miR-200a/200b/429, miR-200c/141), miR-205, and miR-203, known to modulate key EMT factors, are downregulated and hyper-methylated at their promoters. DNMT3A (mainly isoform a) is recruited onto these miRNA promoters, coupled with the increase of H3K27me3/H3K9me3 and/or the decrease of H3K4me3/H3K36me3. Most interestingly, our results reveal the differential expression of two DNMT3A isoforms (a and b) during ex-vivo EMT and a regulatory feedback loop between miR-429 and DNMT3A that can promote and sustain the transition toward a more mesenchymal phenotype. We demonstrate the ability of miR-429 to target DNMT3A 3'UTR and modulate the expression of EMT factors, in particular ZEB1. Survey of the PRAD-TCGA data set shows that patients expressing an EMT-like signature are indeed characterized by down-regulation of the same miRNAs with a diffused hyper-methylation at miR-200c/141 and miR-200a/200b/429 promoters. Finally, we show that miR-1260a also targets DNMT3A, although it does not seem involved in EMT in prostate cancer.

Carcinogenesis. 2021 Oct 23 [Epub ahead of print]

Monica Mancini, Margherita Grasso, Livio Muccillo, Federica Babbio, Francesca Precazzini, Ilaria Castiglioni, Valentina Zanetti, Francesca Rizzo, Christian Pistore, Maria Giovanna De Marino, Michele Zocchi, Valerio Del Vescovo, Valerio Licursi, Giorgio Giurato, Alessandro Weisz, Paola Chiarugi, Lina Sabatino, Michela Alessandra Denti, Ian Marc Bonapace

Department of Biotechnology and Life Sciences, University of Insubria, 21052 Busto Arsizio (VA), Italy., Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Povo (TN), Italy., Department of Sciences and Technologies, University of Sannio, 82100 Benevento, Italy., Laboratory of Molecular Medicine and Genomics, Department of Medicine, Surgery and Dentistry 'Scuola Medica Salernitana', University of Salerno, 84081 Baronissi, Italy., Department of Biology and Biotechnology "Charles Darwin", "Sapienza" University of Rome, Rome, Italy., Department of Biomedical, Experimental and Clinical Sciences 'Mario Serio', University of Florence, Florence, Italy.

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