title: Autophagic flux in glioblastoma cells.
abstract: To establish metabolic context for radiation sensitivity by measuring autophagic flux in two different glioblastoma (GBM) cell lines. Clonogenic survival curve analysis of U87 or U251 cells exposed to γ radiation, fast neutrons, a mixed energy neutron beam (METNB) or Auger electrons from a gadolinium neutron capture (GdNC) reaction suggested other factors, beyond a defective DNA damage response, contribute to cell death of U251 cells. Altered tumor metabolism (autophagy) was hypothesized as a factor in U251 cells' clonogenic response. Each of the four different radiation modalities induced an increase in the number of autophagosomes in both U87 and U251 cells. Changes in the number of autophagosomes can be explained by either induction of autophagy or alterations in autophagic flux so autophagic flux was assayed by p62 immunoblotting or in engineered GBM cells that stably express an autophagy marker protein, LC3B-eGFP-mCherry. Perturbations in later stages of autophagy in U251 cells corresponded with radiation sensitivity of U251 cells irradiated with 10 Gy γ rays. Establishment of altered autophagic flux is a useful biomarker for metabolic stress and provided metabolic context for radiation sensitization to 10 Gy γ rays. These results provide strong evidence for the usefulness of managing tumor cell metabolism as a tool for the enhancement of radiation therapy.
authors.affiliation: a Department of Biological Sciences , Northern Illinois University , DeKalb , IL.
authors.forename: Linda S
authors.initials: LS
authors.lastname: Yasui
authors.affiliation: a Department of Biological Sciences , Northern Illinois University , DeKalb , IL.
authors.forename: Maria
authors.initials: M
authors.lastname: Duran
authors.affiliation: b Fermi National Accelerator Laboratory , Neutron Irradiation Facility , Batavia , IL , USA.
authors.forename: Christine
authors.initials: C
authors.lastname: Andorf
authors.affiliation: b Fermi National Accelerator Laboratory , Neutron Irradiation Facility , Batavia , IL , USA.
authors.forename: Thomas
authors.initials: T
authors.lastname: Kroc
authors.affiliation: a Department of Biological Sciences , Northern Illinois University , DeKalb , IL.
authors.forename: Kathryn
authors.initials: K
authors.lastname: Owens
authors.affiliation: a Department of Biological Sciences , Northern Illinois University , DeKalb , IL.
authors.forename: Kelsie
authors.initials: K
authors.lastname: Allen-Durdan
authors.affiliation: a Department of Biological Sciences , Northern Illinois University , DeKalb , IL.
authors.forename: Andrew
authors.initials: A
authors.lastname: Schuck
authors.affiliation: a Department of Biological Sciences , Northern Illinois University , DeKalb , IL.
authors.forename: Scott
authors.initials: S
authors.lastname: Grayburn
authors.affiliation: a Department of Biological Sciences , Northern Illinois University , DeKalb , IL.
authors.forename: Richard
authors.initials: R
authors.lastname: Becker
mesh_terms: D000071182:Autophagosomes / Q000473:pathology / Q000528:radiation effects*; D001343:Autophagy / Q000528:radiation effects*; D045744:Cell Line, Tumor; D004249:DNA Damage; D004307:Dose-Response Relationship, Radiation; D004583:Electrons / Q000627:therapeutic use*; D005720:Gamma Rays / Q000627:therapeutic use; D005909:Glioblastoma / Q000235:genetics* / Q000473:pathology / Q000532:radiotherapy*; D006801:Humans; D009502:Neutrons / Q000627:therapeutic use; D011879:Radiotherapy Dosage
keywords: Glioblastoma cells; autophagy; cell death; fast neutron; gadolinium neutron capture; metabolic profile; mixed neutron beam