Phosphorylation of Notch1 by Pim kinases promotes oncogenic signaling in breast and prostate cancer cells

Abstract

// Niina M. Santio 1, 2, * , Sebastian K.-J. Landor 3, 4, * , Laura Vahtera 1 , Jani Ylä-Pelto 1, 2 , Elina Paloniemi 5 , Susumu Y. Imanishi 3, 9 , Garry Corthals 3, 10 , Markku Varjosalo 6 , Ganesh Babu Manoharan 7 , Asko Uri 7 , Urban Lendahl 4 , Cecilia Sahlgren 3, 8 , Päivi J. Koskinen 1 1 Section of Genetics and Physiology, Department of Biology, University of Turku, Turku, Finland 2 Drug Research Doctoral Programme, University of Turku, Turku, Finland 3 Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, Turku, Finland 4 Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden 5 Turku University of Applied Sciences, Turku, Finland 6 Institute of Biotechnology, University of Helsinki, Helsinki, Finland 7 Institute of Chemistry, University of Tartu, Tartu, Estonia 8 Department of Biomedical Engineering, Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, The Netherlands 9 Current address: Faculty of Pharmacy, Meijo University, Nagoya, Japan 10 Current address: Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Amsterdam, The Netherlands * These authors have contributed equally to this work Correspondence to: Cecilia Sahlgren, email: cecilia.sahlgren@btk.fi Päivi J. Koskinen, email: paivi.koskinen@utu.fi Keywords: Notch1, Pim kinases, migration, metabolism, tumorigenesis Received: October 14, 2015 Accepted: April 23, 2016 Published: May 07, 2016 ABSTRACT Tumorigenesis is a multistep process involving co-operation between several deregulated oncoproteins. In this study, we unravel previously unrecognized interactions and crosstalk between Pim kinases and the Notch signaling pathway, with implications for both breast and prostate cancer. We identify Notch1 and Notch3, but not Notch2, as novel Pim substrates and demonstrate that for Notch1, the serine residue 2152 is phosphorylated by all three Pim family kinases. This target site is located in the second nuclear localization sequence (NLS) of the Notch1 intracellular domain (N1ICD), and is shown to be important for both nuclear localization and transcriptional activity of N1ICD. Phosphorylation-dependent stimulation of Notch1 signaling promotes migration of prostate cancer cells, balances glucose metabolism in breast cancer cells, and supports in vivo growth of both types of cancer cells on chick embryo chorioallantoic membranes. Furthermore, Pim-induced growth of orthotopic prostate xenografts in mice is associated with enhanced nuclear Notch1 activity. Finally, simultaneous inhibition of Pim and Notch abrogates the cellular responses more efficiently than individual treatments, opening up new vistas for combinatorial cancer therapy.