title: Human lymphoma cells develop resistance to radiation in the presence of astrocytes in vitro.
abstract: BACKGROUND
  Lymphomas growing in the central nervous system exhibit resistance to radiotherapy compared to lymphomas of the lymph nodes. Because astrocytes have been shown to reduce radiation-induced neuronal toxicity, this study hypothesized that astrocytes might protect lymphoma cells from radiation-induced cell killing.
  
  
  METHODS
  A human lymphoma cell line, H9, and normal human astrocytes were grown in culture, exposed to radiation and assessed for cell viability, radiation sensitivity, glutathione content, induction of apoptosis and cell-cycle distribution.
  
  
  RESULTS
  Cell survival assays demonstrated that H9 cells growing in an astrocyte-monolayer and also in an astrocyte-conditioned medium displayed radioresistance compared with H9 cells growing under standard conditions. The radioresistance correlated with accumulation of H9 cells in the G(2) phase of the cell cycle, suppression of radiation-induced apoptosis and coincided with a moderate increase in glutathione.
  
  
  CONCLUSIONS
  The findings of this study suggest that astrocytes may play a role in the radioresistance exhibited by lymphomas of the central nervous system.
authors.affiliation: Department of Radiation Oncology, Tohoku University Graduate School of Medicine, Sendai, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Koto
authors.forename: Heunglae
authors.initials: H
authors.lastname: Cho
authors.forename: Oliver
authors.initials: O
authors.lastname: Riesterer
authors.forename: Uma
authors.initials: U
authors.lastname: Giri
authors.forename: Michael D
authors.initials: MD
authors.lastname: Story
authors.forename: Chul S
authors.initials: CS
authors.lastname: Ha
authors.forename: Uma
authors.initials: U
authors.lastname: Raju
mesh_terms: D017209:Apoptosis / Q000528:radiation effects*; D001253:Astrocytes / Q000502:physiology*; D015153:Blotting, Western; D002453:Cell Cycle / Q000528:radiation effects; D049109:Cell Proliferation / Q000528:radiation effects; D002470:Cell Survival; D018920:Coculture Techniques; D017077:Culture Media, Conditioned / Q000494:pharmacology; D004307:Dose-Response Relationship, Radiation; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D016399:Lymphoma, T-Cell / Q000473:pathology / Q000532:radiotherapy*; D011836:Radiation Tolerance / Q000502:physiology*; D014407:Tumor Cells, Cultured
chemical_list: D017077:Culture Media, Conditioned; D005978:Glutathione