title: ROS1 amplification mediates resistance to gefitinib in glioblastoma cells.
abstract: Glioblastoma (GBM) is the most aggressive brain tumor in adults and remains incurable despite multimodal intensive treatment regimens. The majority of GBM tumors show a mutated or overexpressed EGFR, however, tumors treated with tyrosine kinase inhibitors (TKIs) will inevitably recur highlighting the need to identify signalling pathways involved in GBM resistance to these drugs. To this end, we treated GBM cells that overexpress EGFR with increasing concentrations of gefitinib and isolated resistant clones. These resistant clones were subject to RNAseq and the expression of several genes was found to be upregulated. These genes are mainly tyrosine kinase receptors and include ROS1, DDR1 and PDGFRA and are known to control several downstream targets of EGFR. The upregulation of ROS1 and DDR1 was confirmed at the protein level by western blot. Treatment with a potent and highly specific pyrazole ROS1 inhibitor in ROS1 overexpressing clones led to a sensitization of these cells to low concentrations of gefitinib. Combined treatment with gefitinib and ROS1 inhibitor induces massive cell death by apoptosis following a prolonged S phase cell cycle arrest. Our current study led to the discovery of alternative pathways used by GBM cells to evade cell death following treatment with gefitinib and identifies new therapeutic targets to prevent GBM cell resistance to the drug.
authors.affiliation: Department of Internal Medicine, Division of Hematology and Oncology, Cincinnati, OH, USA.
authors.forename: Hashim
authors.initials: H
authors.lastname: Aljohani
authors.affiliation: Department of Internal Medicine, Division of Hematology and Oncology, Cincinnati, OH, USA.
authors.forename: Robert F
authors.initials: RF
authors.lastname: Koncar
authors.affiliation: Department of Internal Medicine, Cleveland Clinic Foundation, Cleveland, OH, USA.
authors.forename: Ahmad
authors.initials: A
authors.lastname: Zarzour
authors.affiliation: Chemical Kinomics Research Center, Korea Institute of Science and Technology, Hwarangno, Seongbuk-gu, Seoul, Republic of Korea.
authors.forename: Byung Sun
authors.initials: BS
authors.lastname: Park
authors.affiliation: Chemical Kinomics Research Center, Korea Institute of Science and Technology, Hwarangno, Seongbuk-gu, Seoul, Republic of Korea.
authors.forename: So Ha
authors.initials: SH
authors.lastname: Lee
authors.affiliation: Department of Internal Medicine, Division of Hematology and Oncology, Cincinnati, OH, USA.
authors.forename: El Mustapha
authors.initials: el M
authors.lastname: Bahassi
mesh_terms: D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D001932:Brain Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000473:pathology; D059447:Cell Cycle Checkpoints / Q000187:drug effects; D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D004357:Drug Synergism; D000077156:Gefitinib; D005784:Gene Amplification; D005909:Glioblastoma / Q000188:drug therapy / Q000235:genetics / Q000473:pathology; D006801:Humans; D047428:Protein Kinase Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D011799:Quinazolines / Q000008:administration & dosage / Q000494:pharmacology*; D016196:S Phase / Q000187:drug effects
chemical_list: D047428:Protein Kinase Inhibitors; D011518:Proto-Oncogene Proteins; D011799:Quinazolines; D011505:Protein-Tyrosine Kinases; C062333:ROS1 protein, human; D000077156:Gefitinib
keywords: DDR1; EGFR; ROS1; gefitinib; tyrosine kinase inhibitors