title: Dissecting inherent intratumor heterogeneity in patient-derived glioblastoma culture models.
abstract: Molecular profile of glioblastoma multiforme (GBM) revealed 4 subtypes, 2 of which, proneural and mesenchymal, have been predominantly observed, with the latter displaying a more aggressive phenotype and increased therapeutic resistance. Single-cell RNA sequencing revealed that multiple subtypes actually reside within the same tumor, suggesting cellular heterogeneity in GBM. Further, plasticity between these 2 subtypes is observed during tumor recurrence and in response to radiation therapy.
  
  
  
  Patient-derived GBM stemlike cells were cultured as neurospheres. These cells were differentiated in serum by attaching to the culture dishes. The "floating" cells that were not attached/differentiated were harvested from the conditioned medium. The characteristics of these cells were studied with limiting dilution assays and immunofluorescence staining. Cell growth and nuclear factor-kappaB (NFkB) activation were monitored using bioluminescent assays as well as quantitative polymerase chain reaction and western blotting. In vivo tumorigenesis was evaluated in orthotopic xenograft models using bioluminescence imaging.
  
  
  
  Patient-derived GBM stemlike cells undergo differentiation by attaching to the culture dish in serum-containing medium. We observed that a small subset of these cells escape this adhesion/differentiation and grow as floating cells. These cells displayed enhanced cancer stem cell properties with a molecular and phenotypic mesenchymal signature, including resistance to radiation and targeted therapies, a more aggressive tumor formation, and NFkB activation.
  
  
  
  Our results endorse inherent intratumor molecular subtype heterogeneity in glioblastoma and provide a valuable approach to study phenotypic plasticity, which could be applied to find novel therapeutic strategies to eradicate this aggressive tumor and can be extended to other cancer types.
authors.affiliation: Experimental Therapeutics and Molecular Imaging Laboratory, Massachusetts General Hospital, Boston, Massachusetts, USA.|Department of Neurology, Neuro-Oncology Division, Massachusetts General Hospital, Boston, Massachusetts, USA.|Neuroscience Program, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Jian
authors.initials: J
authors.lastname: Teng
authors.affiliation: Experimental Therapeutics and Molecular Imaging Laboratory, Massachusetts General Hospital, Boston, Massachusetts, USA.|Department of Neurology, Neuro-Oncology Division, Massachusetts General Hospital, Boston, Massachusetts, USA.|Neuroscience Program, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Cintia C
authors.initials: CC
authors.lastname: da Hora
authors.affiliation: Experimental Therapeutics and Molecular Imaging Laboratory, Massachusetts General Hospital, Boston, Massachusetts, USA.|Department of Neurology, Neuro-Oncology Division, Massachusetts General Hospital, Boston, Massachusetts, USA.|Neuroscience Program, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Rami S
authors.initials: RS
authors.lastname: Kantar
authors.affiliation: Department of Neurological Surgery, The Ohio State University, Columbus, Ohio, USA.
authors.forename: Ichiro
authors.initials: I
authors.lastname: Nakano
authors.affiliation: Department of Neurosurgery, Massachusetts General Hospital, Boston, Massachusetts, USA.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Wakimoto
authors.affiliation: Department of Neurology, Neuro-Oncology Division, Massachusetts General Hospital, Boston, Massachusetts, USA.|Massachusetts General Hospital Cancer Center, Boston, Massachusetts, USA.
authors.forename: Tracy T
authors.initials: TT
authors.lastname: Batchelor
authors.affiliation: Department of Neurosurgery, Brigham and Women's Hospital, Boston, Massachusetts, USA.
authors.forename: E Antonio
authors.initials: EA
authors.lastname: Chiocca
authors.affiliation: Experimental Therapeutics and Molecular Imaging Laboratory, Massachusetts General Hospital, Boston, Massachusetts, USA.|Department of Neurology, Neuro-Oncology Division, Massachusetts General Hospital, Boston, Massachusetts, USA.|Neuroscience Program, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Christian E
authors.initials: CE
authors.lastname: Badr
authors.affiliation: Experimental Therapeutics and Molecular Imaging Laboratory, Massachusetts General Hospital, Boston, Massachusetts, USA.|Department of Neurology, Neuro-Oncology Division, Massachusetts General Hospital, Boston, Massachusetts, USA.|Neuroscience Program, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Bakhos A
authors.initials: BA
authors.lastname: Tannous
mesh_terms: D000818:Animals; D017209:Apoptosis; D001932:Brain Neoplasms / Q000145:classification / Q000235:genetics / Q000473:pathology*; D002465:Cell Movement; D049109:Cell Proliferation; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D005909:Glioblastoma / Q000145:classification / Q000235:genetics / Q000473:pathology*; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D014411:Neoplastic Stem Cells / Q000378:metabolism / Q000473:pathology*; D014407:Tumor Cells, Cultured; D023041:Xenograft Model Antitumor Assays
keywords: cancer stem cells; differentiation; glioblastoma; intratumor heterogeneity; mesenchymal transition