Abstract 3809: Protein arginine methyltransferase 1 (PRMT1) is a candidate therapeutic target for breast cancers

Abstract

Abstract Triple-negative breast cancer (TNBC) represents a subgroup of breast cancers associated with the most aggressive clinical behavior. No targeted therapy is currently available for the treatment of patients with TNBC. In the present study, we found that Protein Arginine Methyltransferase 1 (PRMT1) is overexpressed in TNBC at the mRNA level. At the protein level, PRMT1 is overexpressed in all breast cancer subtypes compared to normal breast tissues. The depletion of PRMT1 using siRNA in breast cancer cell lines triggered apoptosis, reduced cell viability and the ability to form colonies in an anchorage-independent manner. Treatment with a PRMT1 inhibitor blocked proliferation specifically in breast cancer cells, with no effect in normal breast cells. Importantly, the expression of PRMT1 is an indicator of prognosis and response to treatment specifically in TNBC patients. To address the cellular pathways regulated by PRMT1, we identified its protein partners by mass spectrometry and the transcriptomic changes following its depletion in TNBC cell lines. Interestingly, we found that PRMT1 directly activates key oncogenic pathways. Furthermore, we found a synergistic interaction between PRMT1 inhibitors and inhibitors for some of those pathways. We show that PRMT1 activity is necessary for breast cancer cell survival and oncogenic pathway activation. Altogether, our results point out PRMT1 as an emerging target for the treatment of breast cancers. Citation Format: David Silvestre, Amélie Brisson, Bérengère Marty-Prouvost, Mengliang Ye, Hélène Bonsang, Virginie Maire, Damarys Loew, David Gentien, Didier Meseure, Fabien Reyal, Gordon C. Tucker, Sergio Roman-Roman, Thierry Dubois. Protein arginine methyltransferase 1 (PRMT1) is a candidate therapeutic target for breast cancers. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3809.