Characterization of brain tumor initiating cells isolated from an animal model of CNS primitive neuroectodermal tumors

// Sergey Malchenko 1 , Simone T. Sredni 2, 3, * , Jerusha Boyineni 1, * , Yingtao Bi 4, 5 , Naira V. Margaryan 6 , Maheedhara R. Guda 1 , Yulia Kostenko 1 , Tadanori Tomita 2 , Ramana V. Davuluri 4 , Kiran Velpula 1 , Mary J.C. Hendrix 6, 7 and Marcelo B. Soares 1 1 Department of Cancer Biology & Pharmacology, University of Illinois College of Medicine, Peoria, Illinois, United States of America 2 Department of Surgery, Division of Pediatric Neurosurgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America 3 Cancer Biology and Epigenomics Program at The Stanley Manne Children’s Research Institute, Ann & Robert H. Lurie Children’s Hospital of Chicago, Chicago, Illinois, United States of America 4 Department of Preventive Medicine, Division of Health and Biomedical Informatics, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America 5 AbbVie Bioresearch Center, Worcester, Massachusetts, United States of America 6 Department of Biochemistry, Robert C. Byrd Health Sciences Center and Cancer Institute, West Virginia University, Morgantown, West Virginia, United States of America 7 Department of Biology, Shepherd University, Shepherdstown, West Virginia, United States of America * These authors have contributed equally to this work Correspondence to: Sergey Malchenko, email: sergeynm@uicomp.uic.edu Keywords: CNS-PNET animal model; radial glia; brain tumor-initiating cells; RNA/DNA-seq; gene signature Received: December 10, 2017 Accepted: January 30, 2018 Published: February 09, 2018 ABSTRACT CNS Primitive Neuroectodermal tumors (CNS-PNETs) are members of the embryonal family of malignant childhood brain tumors, which remain refractory to current therapeutic treatments. Current paradigm of brain tumorigenesis implicates brain tumor-initiating cells (BTIC) in the onset of tumorigenesis and tumor maintenance. However, despite their significance, there is currently no comprehensive characterization of CNS-PNETs BTICs. Recently, we described an animal model of CNS-PNET generated by orthotopic transplantation of human Radial Glial (RG) cells - the progenitor cells for adult neural stem cells (NSC) - into NOD-SCID mice brain and proposed that BTICs may play a role in the maintenance of these tumors. Here we report the characterization of BTIC lines derived from this CNS-PNET animal model. BTIC’s orthotopic transplantation generated highly aggressive tumors also characterized as CNS-PNETs. The BTICs have the hallmarks of NSCs as they demonstrate self-renewing capacity and have the ability to differentiate into astrocytes and early migrating neurons. Moreover, the cells demonstrate aberrant accumulation of wild type tumor-suppressor protein p53, indicating its functional inactivation, highly up-regulated levels of onco-protein cMYC and the BTIC marker OCT3/4, along with metabolic switch to glycolysis - suggesting that these changes occurred in the early stages of tumorigenesis. Furthermore, based on RNA- and DNA-seq data, the BTICs did not acquire any transcriptome-changing genomic alterations indicating that the onset of tumorigenesis may be epigenetically driven. The study of these BTIC self-renewing cells in our model may enable uncovering the molecular alterations that are responsible for the onset and maintenance of the malignant PNET phenotype.