Integrated transcriptomic and proteomic analysis identifies protein kinase CK2 as a key signaling node in an inflammatory cytokine network in ovarian cancer cells

Abstract

// Hagen Kulbe 1, 8 , Francesco Iorio 4, 6 , Probir Chakravarty 3 , Carla S. Milagre 1 , Robert Moore 1 , Richard G. Thompson 1 , Gemma Everitt 1 , Monica Canosa 1 , Alexander Montoya 2 , Denis Drygin 5 , Ioana Braicu 7, 8 , Jalid Sehouli 7, 8 , Julio Saez-Rodriguez 4 , Pedro R. Cutillas 2 , Frances R. Balkwill 1 1 Centre for Cancer and Inflammation, Barts Cancer Institute, Queen Mary University of London, London, UK 2 Centre for Haemato-Oncology, Barts Cancer Institute, Queen Mary University of London, London, UK 3 Bioinformatics Core, The Francis Crick Institute, London, UK 4 European Molecular Biology Laboratory – European Bioinformatics Institute, EMBL-EBI, Cambridge, UK 5 Pimera, Inc., San Diego, CA, USA 6 Cancer Genome Project, Wellcome Trust Sanger Institute, Cambridge, UK 7 Tumorbank Ovarian Cancer Network, Department of Gynecology, Charité Universitätsmedizin Berlin, Berlin, Germany 8 Department of Gynecology, Charité Universitätsmedizin Berlin, Berlin, Germany Correspondence to: Frances R. Balkwill, e-mail: f.balkwill@qmul.ac.uk Keywords: inflammatory cytokine networks, ovarian cancer, microenvironment, systems biology, therapeutics Received: December 14, 2015      Accepted: January 26, 2016      Published: February 8, 2016 ABSTRACT We previously showed how key pathways in cancer-related inflammation and Notch signaling are part of an autocrine malignant cell network in ovarian cancer. This network, which we named the “TNF network”, has paracrine actions within the tumor microenvironment, influencing angiogenesis and the immune cell infiltrate. The aim of this study was to identify critical regulators in the signaling pathways of the TNF network in ovarian cancer cells that might be therapeutic targets. To achieve our aim, we used a systems biology approach, combining data from phospho-proteomic mass spectrometry and gene expression array analysis. Among the potential therapeutic kinase targets identified was the protein kinase Casein kinase II (CK2). Knockdown of CK2 expression in malignant cells by siRNA or treatment with the specific CK2 inhibitor CX-4945 significantly decreased Notch signaling and reduced constitutive cytokine release in ovarian cancer cell lines that expressed the TNF network as well as malignant cells isolated from high grade serous ovarian cancer ascites. The expression of the same cytokines was also inhibited after treatment with CX-4945 in a 3D organotypic model. CK2 inhibition was associated with concomitant inhibition of proliferative activity, reduced angiogenesis and experimental peritoneal ovarian tumor growth. In conclusion, we have identified kinases, particularly CK2, associated with the TNF network that may play a central role in sustaining the cytokine network and/or mediating its effects in ovarian cancer.