title: Irradiation with carbon ion beams induces apoptosis, autophagy, and cellular senescence in a human glioma-derived cell line.
abstract: OBJECTIVE
  We examined biological responses of human glioma cells to irradiation with carbon ion beams (C-ions).
  
  
  METHODS
  A human glioma-derived cell line, NP-2, was irradiated with C-ions. Apoptotic cell nuclei were stained with Hoechst 33342. Induction of autophagy was examined either by staining cells with monodansylcadaverine (MDC) or by Western blotting to detect conversion of microtuble-associated protein light chain 3 (MAP-LC3) (LC3-I) to the membrane-bound form (LC3-II). Cellular senescence markers including induction of senescence-associated beta-galactosidase (SA-beta-gal) were examined. The mean telomere length of irradiated cells was determined by Southern blot hybridization. Expression of tumor suppressor p53 and cyclin/cyclin-dependent kinase inhibitor p21(WAF1/CIP1) in the irradiated cells was analyzed by Western blotting.
  
  
  RESULTS
  When NP-2 cells were irradiated with C-ions at 6 Gy, the major population of the cells died of apoptosis and autophagy. The residual fraction of attached cells (<1% of initially irradiated cells) could not form a colony: however, they showed a morphological phenotype consistent with cellular senescence, that is, enlarged and flattened appearance. The senescent nature of these attached cells was further indicated by staining for SA-beta-gal. The mean telomere length was not changed after irradiation with C-ions. Phosphorylation of p53 at serine 15 as well as the expression of p21(WAF1/CIP1) was induced in NP-2 cells after irradiation. Furthermore, we found that irradiation with C-ions induced cellular senescence in a human glioma cell line lacking functional p53.
  
  
  CONCLUSIONS
  Irradiation with C-ions induced apoptosis, autophagy, and cellular senescence in human glioma cells.
authors.affiliation: Department of Virology and Preventive Medicine, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Jinno-Oue
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Shimizu
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Hamada
authors.forename: Seiichi
authors.initials: S
authors.lastname: Wada
authors.forename: Atsushi
authors.initials: A
authors.lastname: Tanaka
authors.forename: Masahiko
authors.initials: M
authors.lastname: Shinagawa
authors.forename: Takahiro
authors.initials: T
authors.lastname: Ohtsuki
authors.forename: Takahisa
authors.initials: T
authors.lastname: Mori
authors.forename: Manujendra N
authors.initials: MN
authors.lastname: Saha
authors.forename: Ariful S
authors.initials: AS
authors.lastname: Hoque
authors.forename: Salequl
authors.initials: S
authors.lastname: Islam
authors.forename: Kimitaka
authors.initials: K
authors.lastname: Kogure
authors.forename: Tomoo
authors.initials: T
authors.lastname: Funayama
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Kobayashi
authors.forename: Hiroo
authors.initials: H
authors.lastname: Hoshino
mesh_terms: D017209:Apoptosis; D001343:Autophagy; D002244:Carbon / Q000494:pharmacology*; D045744:Cell Line, Tumor / Q000528:radiation effects; D016922:Cellular Senescence; D003114:Colony-Forming Units Assay; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D005910:Glioma / Q000378:metabolism / Q000473:pathology; D020450:Heavy Ions; D006801:Humans; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D016615:Telomere / Q000473:pathology; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D050759:Cyclin-Dependent Kinase Inhibitor p21; D008869:Microtubule-Associated Proteins; D016159:Tumor Suppressor Protein p53; D002244:Carbon; D001616:beta-Galactosidase