Silencing of casein kinase 1 delta reduces migration and metastasis of triple negative breast cancer cells

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// Isabelle Bar 1 , Ahmad Merhi 1, 2 , Lionel Larbanoix 3, 4 , Manuel Constant 1 , Sandy Haussy 1 , Sophie Laurent 3, 4 , Jean-Luc Canon 5 and Paul Delrée 6 1 Laboratory of Translational Oncology, Institute of Pathology and Genetics/Grand Hôpital de Charleroi, Gosselies 6041, Belgium 2 IPG BioBank, Institute of Pathology and Genetics, Gosselies 6041, Belgium 3 Center for Microscopy and Molecular Imaging (CMMI), Université de Mons (UMONS), Charleroi 6041, Belgium 4 Department of General, Organic and Biomedical Chemistry, NMR and Molecular Imaging Laboratory, Université de Mons (UMONS), Mons 7000, Belgium 5 Service of Oncology-Hematology, Grand Hôpital de Charleroi, Charleroi 6000, Belgium 6 Department of Pathology, Institute of Pathology and Genetics, Gosselies 6041, Belgium Correspondence to: Isabelle Bar, email: isabelle.bar@ipg.be Keywords: triple-negative breast cancer; migration; metastasis; tight junction; casein kinase 1 delta Received: January 11, 2018 Accepted: June 22, 2018 Published: July 20, 2018 ABSTRACT The casein kinase 1 delta (CSNK1D) is a conserved serine/threonine protein kinase that regulates diverse cellular processes including cell cycle progression, circadian rhythm, and neurite outgrowth. Aberrant expression of CSNK1D is described in several cancer types including breast cancer, where it is amplified in about 30% of triple negative breast (TNBC). Here, we have investigated the function of CSNK1D in triple negative cancer cell migration and metastasis. By using immunohistochemistry and in situ hybridization, we found that CNSK1D is highly expressed in primary tumor cells and in tumor cells invading lymphatic nodes compared to non-metastatic tumors. In vitro , knock-down of CSNK1D expression with specific shRNAs in the breast cancer cell line MDA-MB-231 markedly inhibited cancer cell proliferation, invasion and migration and affected the expression of the tight junction proteins claudin 1, occludin and the junction adhesion molecule A. In vivo , the inactivation of CSNK1D reduced lung metastasis in MDA-MB-231 breast cancer xenografts. Altogether, our results indicate that the downregulation of CSNK1D expression inhibits the proliferation and reduces the migration and the metastasis of breast cancer cells. As numerous inhibitors of CSNK1D are currently under development, this might represent an attractive therapeutic target for the treatment of TNBC.