Quinomycin A targets Notch signaling pathway in pancreatic cancer stem cells

// Sivapriya Ponnurangam 1, 2 , Prasad R. Dandawate 1, 2 , Animesh Dhar 3, 7 , Ossama W. Tawfik 4, 7 , Rajashri R. Parab 8 , Prabhu Dutt Mishra 8 , Prafull Ranadive 8 , Rajiv Sharma 8 , Girish Mahajan 8 , Shahid Umar 1, 2, 7 , Scott J. Weir 5, 7 , Aravind Sugumar 6, 7 , Roy A. Jensen 4, 7 , Subhash B. Padhye 3, 9 , Arun Balakrishnan 8 , Shrikant Anant 1, 2, 7 , Dharmalingam Subramaniam 1, 2, 7 1 Department of Molecular and Integrative Physiology, The University of Kansas Medical Center, Kansas City, KS 66160, USA 2 Department of Surgery, The University of Kansas Medical Center, Kansas City, KS 66160, USA 3 Department of Cancer Biology, The University of Kansas Medical Center, Kansas City, KS 66160, USA 4 Department of Pathology and Laboratory Medicine, The University of Kansas Medical Center, Kansas City, KS 66160, USA 5 Department of Pharmacology, Toxicology and Therapeutics, The University of Kansas Medical Center, Kansas City, KS 66160, USA 6 Department of Internal Medicine, The University of Kansas Medical Center, Kansas City, KS 66160, USA 7 The University of Kansas Cancer Center, Kansas City, KS 66160, USA 8 Piramal Life Sciences Inc, Goregaon East, Mumbai 400063, India 9 Interdisciplinary Science and Technology Research Academy, Abeda Inamdar Senior College, Azam Campus, Pune, 411001, India Correspondence to: Dharmalingam Subramaniam, e-mail: dsubramaniam@kumc.edu Shrikant Anant, e-mail: sanant@kumc.edu Keywords: DCLK1, apoptosis, tumor xenograft, Hes1, NICD Received: August 21, 2015      Accepted: November 21, 2015      Published: December 11, 2015 ABSTRACT Cancer stem cells (CSCs) appear to explain many aspects of the neoplastic evolution of tumors and likely account for enhanced therapeutic resistance following treatment. Dysregulated Notch signaling, which affects CSCs plays an important role in pancreatic cancer progression. We have determined the ability of Quinomycin to inhibit CSCs and the Notch signaling pathway. Quinomycin treatment resulted in significant inhibition of proliferation and colony formation in pancreatic cancer cell lines, but not in normal pancreatic epithelial cells. Moreover, Quinomycin affected pancreatosphere formation. The compound also decreased the expression of CSC marker proteins DCLK1, CD44, CD24 and EPCAM. In addition, flow cytometry studies demonstrated that Quinomycin reduced the number of DCLK1+ cells. Furthermore, levels of Notch 1–4 receptors, their ligands Jagged1, Jagged2, DLL1, DLL3, DLL4 and the downstream target protein Hes-1 were reduced. The γ-secretase complex proteins, Presenilin 1, Nicastrin, Pen2, and APH-1, required for Notch activation also exhibited decreased expression. Ectopic expression of the Notch Intracellular Domain (NICD) partially rescued the cells from Quinomycin mediated growth suppression. To determine the effect of Quinomycin on tumor growth in vivo , nude mice carrying tumor xenografts were administered Quinomycin intraperitoneally every day for 21 days. Treatment with the compound significantly inhibited tumor xenograft growth, coupled with significant reduction in the expression of CSC markers and Notch signaling proteins. Together, these data suggest that Quinomycin is a potent inhibitor of pancreatic cancer that targets the stem cells by inhibiting Notch signaling proteins.