Targeting intracellular B2 receptors using novel cell-penetrating antagonists to arrest growth and induce apoptosis in human triple-negative breast cancer
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Céléna Dubuc1,2,*, Martin Savard1,2,*, Veronica Bovenzi1,2,*, Andrée Lessard3, Audrey Fortier1,2, Jérôme Côté1,2, Witold Neugebauer1,2, Flavio Rizzolio4,5, Sameh Geha6, Antonio Giordano4, Sylvain Chemtob7 and Fernand Gobeil1,2
1Department of Pharmacology and Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada
2Institute of Pharmacology, Université de Sherbrooke, Sherbrooke, Québec, Canada
3Department of Psychiatry, Maryland Psychiatric Research Center, University of Maryland School of Medicine, Baltimore, MD, United States
4Department of Biology, Sbarro Institute for Cancer Research and Molecular Medicine, Temple University, Philadelphia, PA, USA
5Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca' Foscari Venezia, Mestre-Venezia, Italy
6Department of Pathology, Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, Québec, Canada
7Department of Pediatrics, Centre Hospitalier Universitaire Sainte-Justine Research Center, Montréal, Québec, Canada
*Joint first authorship
Fernand Gobeil, email: firstname.lastname@example.org
Keywords: triple-negative breast cancer; kinins; cell-permeable antagonist; nuclear GPCRs; intracrine signaling
Received: June 08, 2017 Accepted: October 02, 2017 Published: January 05, 2018
G protein-coupled receptors (GPCRs) are integral cell-surface proteins having a central role in tumor growth and metastasis. However, several GPCRs retain an atypical intracellular/nuclear location in various types of cancer. The pathological significance of this is currently unknown. Here we extend this observation by showing that the bradykinin B2R (BK-B2R) is nuclearly expressed in the human triple-negative breast cancer (TNBC) cell line MDA-MB-231 and in human clinical specimens of TNBC. We posited that these “nuclearized” receptors could be involved in oncogenic signaling linked to aberrant growth and survival maintenance of TNBC. We used cell-penetrating BK-B2R antagonists, including FR173657 and novel transducible, cell-permeable forms of the peptide B2R antagonist HOE 140 (NG68, NG134) to demonstrate their superior efficacy over impermeable ones (HOE 140), in blocking proliferation and promoting apoptosis of MDA-MB-231 cells. Some showed an even greater antineoplastic activity over conventional chemotherapeutic drugs in vitro. The cell-permeable B2R antagonists had less to no anticancer effects on B2R shRNA-knockdown or non-B2R expressing (COS-1) cells, indicating specificity in their action. Possible mechanisms of their anticancer effects may involve activation of p38kinase/p27Kip1 pathways. Together, our data support the existence of a possible intracrine signaling pathway via internal/nuclear B2R, critical for the growth of TNBC cells, and identify new chemical entities that enable to target the corresponding intracellular GPCRs.
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