Preclinical ReportsA novel screening approach comparing kinase activity of small molecule inhibitors with similar molecular structures and distinct biologic effects in triple-negative breast cancer to identify targetable signaling pathwaysMatossian, Margarite D.a; Burks, Hope E.a; Elliott, Stevena; Hoang, Van T.a; Zuercher, William J.b,,c; Wells, Carrowb; Drewry, David H.b; Kapadia, Niravb; Chang, Tiffanya; Yan, Thomasa; Windsor, Gabrielle O.a; Nguyen, Khoaa; Fang, Fangd; Nephew, Kenneth P.d; Buechlein, Aarone; Rusch, Douglas B.e; Sabol, Rachel A.e,,g; Ucar, Deniz A.g; Zabaleta, Jovannyg; Miele, Luciog; Bunnell, Bruce A.f,,h; Collins-Burow, Bridgette M.a; Burow, Matthew E.a,,hAuthor Information aDepartment of Medicine, Tulane University School of Medicine, New Orleans, Louisiana bStructural Genomics Consortium, UNC Eshelman School of Pharmacy cLineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina dMedical Sciences Program, Indiana University School of Medicine eCenter for Genomics and Bioinformatics, Indiana University, Bloomington, Indiana fDepartment of Pharmacology, Tulane University School of Medicine, New Orleans, Louisiana gDepartment of Genetics, Louisiana State University Health Sciences Center, Stanley S. Scott Cancer Center hTulane University School of Medicine, Center for Stem Cell Research and Regenerative Medicine, New Orleans, Louisiana, USA Received 18 February 2020 Revised form accepted 23 May 2020 Supplemental Digital Content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's website, www.anti-cancerdrugs.com. Correspondence to Matthew E. Burow, PhD, Department of Medicine, Section of Hematology and Oncology, Tulane University, New Orleans, LA 70112, USA, Tel: +504 988 6688; fax: +504 988 6215; e-mail: firstname.lastname@example.org Anti-Cancer Drugs: September 2020 - Volume 31 - Issue 8 - p 759-775 doi: 10.1097/CAD.0000000000000962 Buy SDC Metrics Abstract Breast cancer affects women globally; the majority of breast cancer-related mortalities are due to metastasis. Acquisition of a mesenchymal phenotype has been implicated in the progression of breast cancer cells to an invasive, metastatic state. Triple-negative breast cancer (TNBC) subtypes have high rates of metastases, recurrence, and have poorer prognoses compared to other breast cancer types, partially due to lack of commonly targeted receptors. Kinases have diverse and pivotal functions in metastasis in TNBC, and discovery of new kinase targets for TNBC is warranted. We previously used a screening approach to identify intermediate-synthesis nonpotent, nonselective small-molecule inhibitors from the Published Kinase Inhibitor Set that reversed the mesenchymal phenotype in TNBC cells. Two of these inhibitors (GSK346294A and GSK448459A) are structurally similar, but have unique kinase activity profiles and exhibited differential biologic effects on TNBC cells, specifically on epithelial-to-mesenchymal transition (EMT). Here, we further interrogate these effects and compare activity of these inhibitors on transwell migration, gene (qRT-PCR) and protein (western blot) expressions, and cancer stem cell-like behavior. We incorporated translational patient-derived xenograft models in these studies, and we focused on the lead inhibitor hit, GSK346294A, to demonstrate the utility of our comparative analysis as a screening modality to identify novel kinase targets and signaling pathways to pursue in TNBC. This study introduces a new method for discovering novel kinase targets that reverse the EMT phenotype; this screening approach can be applied to all cancer types and is not limited to breast cancer. Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.