title: USP1 targeting impedes GBM growth by inhibiting stem cell maintenance and radioresistance.
abstract: BACKGROUND
  Clinical benefits from standard therapies against glioblastoma (GBM) are limited in part due to intrinsic radio- and chemoresistance of GBM and inefficient targeting of GBM stem-like cells (GSCs). Novel therapeutic approaches that overcome treatment resistance and diminish stem-like properties of GBM are needed.
  
  
  METHODS
  We determined the expression levels of ubiquitination-specific proteases (USPs) by transcriptome analysis and found that USP1 is highly expressed in GBM. Using the patient GBM-derived primary tumor cells, we inhibited USP1 by shRNA-mediated knockdown or its specific inhibitor pimozide and evaluated the effects on stem cell marker expression, proliferation, and clonogenic growth of tumor cells.
  
  
  RESULTS
  USP1 was highly expressed in gliomas relative to normal brain tissues and more preferentially in GSC enrichment marker (CD133 or CD15) positive cells. USP1 positively regulated the protein stability of the ID1 and CHEK1, critical regulators of DNA damage response and stem cell maintenance. Targeting USP1 by RNA interference or treatment with a chemical USP1 inhibitor attenuated clonogenic growth and survival of GSCs and enhanced radiosensitivity of GBM cells. Finally, USP1 inhibition alone or in combination with radiation significantly prolonged the survival of tumor-bearing mice.
  
  
  CONCLUSIONS
  USP1-mediated protein stabilization promotes GSC maintenance and treatment resistance, thereby providing a rationale for USP1 inhibition as a potential therapeutic approach against GBM.
authors.affiliation: Department of Neurosurgery, Samsung Medical Center and Samsung Biomedical Research Institute, Seoul, Korea (J.-K.L., Y.Y., H.Y., W.K., D.-H.N.); Graduate School of Health Science & Technology, Samsung Advanced Institute for Health Science & Technology, Sungkyunkwan University, Seoul, Korea (N.C., H.C., Y.T.O., Y.Y., D.-H.N.); Department of Anatomy and Cell Biology, Sungkyunkwan University School of Medicine, Seoul, Korea (K.M.J.); Department of Stem Cell Biology and Regenerative Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio (E.K., Y.S., G.I.M., J.L.).
authors.forename: Jin-Ku
authors.initials: JK
authors.lastname: Lee
authors.affiliation: Department of Neurosurgery, Samsung Medical Center and Samsung Biomedical Research Institute, Seoul, Korea (J.-K.L., Y.Y., H.Y., W.K., D.-H.N.); Graduate School of Health Science & Technology, Samsung Advanced Institute for Health Science & Technology, Sungkyunkwan University, Seoul, Korea (N.C., H.C., Y.T.O., Y.Y., D.-H.N.); Department of Anatomy and Cell Biology, Sungkyunkwan University School of Medicine, Seoul, Korea (K.M.J.); Department of Stem Cell Biology and Regenerative Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio (E.K., Y.S., G.I.M., J.L.).
authors.forename: Nakho
authors.initials: N
authors.lastname: Chang
authors.affiliation: Department of Neurosurgery, Samsung Medical Center and Samsung Biomedical Research Institute, Seoul, Korea (J.-K.L., Y.Y., H.Y., W.K., D.-H.N.); Graduate School of Health Science & Technology, Samsung Advanced Institute for Health Science & Technology, Sungkyunkwan University, Seoul, Korea (N.C., H.C., Y.T.O., Y.Y., D.-H.N.); Department of Anatomy and Cell Biology, Sungkyunkwan University School of Medicine, Seoul, Korea (K.M.J.); Department of Stem Cell Biology and Regenerative Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio (E.K., Y.S., G.I.M., J.L.).
authors.forename: Yeup
authors.initials: Y
authors.lastname: Yoon
authors.affiliation: Department of Neurosurgery, Samsung Medical Center and Samsung Biomedical Research Institute, Seoul, Korea (J.-K.L., Y.Y., H.Y., W.K., D.-H.N.); Graduate School of Health Science & Technology, Samsung Advanced Institute for Health Science & Technology, Sungkyunkwan University, Seoul, Korea (N.C., H.C., Y.T.O., Y.Y., D.-H.N.); Department of Anatomy and Cell Biology, Sungkyunkwan University School of Medicine, Seoul, Korea (K.M.J.); Department of Stem Cell Biology and Regenerative Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio (E.K., Y.S., G.I.M., J.L.).
authors.forename: Heekyoung
authors.initials: H
authors.lastname: Yang
authors.affiliation: Department of Neurosurgery, Samsung Medical Center and Samsung Biomedical Research Institute, Seoul, Korea (J.-K.L., Y.Y., H.Y., W.K., D.-H.N.); Graduate School of Health Science & Technology, Samsung Advanced Institute for Health Science & Technology, Sungkyunkwan University, Seoul, Korea (N.C., H.C., Y.T.O., Y.Y., D.-H.N.); Department of Anatomy and Cell Biology, Sungkyunkwan University School of Medicine, Seoul, Korea (K.M.J.); Department of Stem Cell Biology and Regenerative Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio (E.K., Y.S., G.I.M., J.L.).
authors.forename: Heejin
authors.initials: H
authors.lastname: Cho
authors.affiliation: Department of Neurosurgery, Samsung Medical Center and Samsung Biomedical Research Institute, Seoul, Korea (J.-K.L., Y.Y., H.Y., W.K., D.-H.N.); Graduate School of Health Science & Technology, Samsung Advanced Institute for Health Science & Technology, Sungkyunkwan University, Seoul, Korea (N.C., H.C., Y.T.O., Y.Y., D.-H.N.); Department of Anatomy and Cell Biology, Sungkyunkwan University School of Medicine, Seoul, Korea (K.M.J.); Department of Stem Cell Biology and Regenerative Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio (E.K., Y.S., G.I.M., J.L.).
authors.forename: Eunhee
authors.initials: E
authors.lastname: Kim
authors.affiliation: Department of Neurosurgery, Samsung Medical Center and Samsung Biomedical Research Institute, Seoul, Korea (J.-K.L., Y.Y., H.Y., W.K., D.-H.N.); Graduate School of Health Science & Technology, Samsung Advanced Institute for Health Science & Technology, Sungkyunkwan University, Seoul, Korea (N.C., H.C., Y.T.O., Y.Y., D.-H.N.); Department of Anatomy and Cell Biology, Sungkyunkwan University School of Medicine, Seoul, Korea (K.M.J.); Department of Stem Cell Biology and Regenerative Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio (E.K., Y.S., G.I.M., J.L.).
authors.forename: Yongjae
authors.initials: Y
authors.lastname: Shin
authors.affiliation: Department of Neurosurgery, Samsung Medical Center and Samsung Biomedical Research Institute, Seoul, Korea (J.-K.L., Y.Y., H.Y., W.K., D.-H.N.); Graduate School of Health Science & Technology, Samsung Advanced Institute for Health Science & Technology, Sungkyunkwan University, Seoul, Korea (N.C., H.C., Y.T.O., Y.Y., D.-H.N.); Department of Anatomy and Cell Biology, Sungkyunkwan University School of Medicine, Seoul, Korea (K.M.J.); Department of Stem Cell Biology and Regenerative Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio (E.K., Y.S., G.I.M., J.L.).
authors.forename: Wonyoung
authors.initials: W
authors.lastname: Kang
authors.affiliation: Department of Neurosurgery, Samsung Medical Center and Samsung Biomedical Research Institute, Seoul, Korea (J.-K.L., Y.Y., H.Y., W.K., D.-H.N.); Graduate School of Health Science & Technology, Samsung Advanced Institute for Health Science & Technology, Sungkyunkwan University, Seoul, Korea (N.C., H.C., Y.T.O., Y.Y., D.-H.N.); Department of Anatomy and Cell Biology, Sungkyunkwan University School of Medicine, Seoul, Korea (K.M.J.); Department of Stem Cell Biology and Regenerative Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio (E.K., Y.S., G.I.M., J.L.).
authors.forename: Young Taek
authors.initials: YT
authors.lastname: Oh
authors.affiliation: Department of Neurosurgery, Samsung Medical Center and Samsung Biomedical Research Institute, Seoul, Korea (J.-K.L., Y.Y., H.Y., W.K., D.-H.N.); Graduate School of Health Science & Technology, Samsung Advanced Institute for Health Science & Technology, Sungkyunkwan University, Seoul, Korea (N.C., H.C., Y.T.O., Y.Y., D.-H.N.); Department of Anatomy and Cell Biology, Sungkyunkwan University School of Medicine, Seoul, Korea (K.M.J.); Department of Stem Cell Biology and Regenerative Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio (E.K., Y.S., G.I.M., J.L.).
authors.forename: Gyeong In
authors.initials: GI
authors.lastname: Mun
authors.affiliation: Department of Neurosurgery, Samsung Medical Center and Samsung Biomedical Research Institute, Seoul, Korea (J.-K.L., Y.Y., H.Y., W.K., D.-H.N.); Graduate School of Health Science & Technology, Samsung Advanced Institute for Health Science & Technology, Sungkyunkwan University, Seoul, Korea (N.C., H.C., Y.T.O., Y.Y., D.-H.N.); Department of Anatomy and Cell Biology, Sungkyunkwan University School of Medicine, Seoul, Korea (K.M.J.); Department of Stem Cell Biology and Regenerative Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio (E.K., Y.S., G.I.M., J.L.).
authors.forename: Kyeung Min
authors.initials: KM
authors.lastname: Joo
authors.affiliation: Department of Neurosurgery, Samsung Medical Center and Samsung Biomedical Research Institute, Seoul, Korea (J.-K.L., Y.Y., H.Y., W.K., D.-H.N.); Graduate School of Health Science & Technology, Samsung Advanced Institute for Health Science & Technology, Sungkyunkwan University, Seoul, Korea (N.C., H.C., Y.T.O., Y.Y., D.-H.N.); Department of Anatomy and Cell Biology, Sungkyunkwan University School of Medicine, Seoul, Korea (K.M.J.); Department of Stem Cell Biology and Regenerative Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio (E.K., Y.S., G.I.M., J.L.).
authors.forename: Do-Hyun
authors.initials: DH
authors.lastname: Nam
authors.affiliation: Department of Neurosurgery, Samsung Medical Center and Samsung Biomedical Research Institute, Seoul, Korea (J.-K.L., Y.Y., H.Y., W.K., D.-H.N.); Graduate School of Health Science & Technology, Samsung Advanced Institute for Health Science & Technology, Sungkyunkwan University, Seoul, Korea (N.C., H.C., Y.T.O., Y.Y., D.-H.N.); Department of Anatomy and Cell Biology, Sungkyunkwan University School of Medicine, Seoul, Korea (K.M.J.); Department of Stem Cell Biology and Regenerative Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio (E.K., Y.S., G.I.M., J.L.).
authors.forename: Jeongwu
authors.initials: J
authors.lastname: Lee
mesh_terms: D000818:Animals; D001932:Brain Neoplasms / Q000378:metabolism*; D000071877:Checkpoint Kinase 1; D005909:Glioblastoma / Q000378:metabolism*; D006801:Humans; D051798:Inhibitor of Differentiation Protein 1 / Q000378:metabolism; D051379:Mice; D014411:Neoplastic Stem Cells / Q000378:metabolism* / Q000528:radiation effects*; D011494:Protein Kinases / Q000378:metabolism; D014407:Tumor Cells, Cultured; D064570:Ubiquitin-Specific Proteases / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: C497453:ID1 protein, human; D051798:Inhibitor of Differentiation Protein 1; D011494:Protein Kinases; C000605867:CHEK1 protein, human; D000071877:Checkpoint Kinase 1; C579228:USP1 protein, human; D064570:Ubiquitin-Specific Proteases
keywords: deubiquitination; glioblastoma stem cells; targeted therapy