Glutathione depletion and carbon ion radiation potentiate clustered DNA lesions, cell death and prevent chromosomal changes in cancer cells progeny

PLoS One. 2012;7(11):e44367. doi: 10.1371/journal.pone.0044367. Epub 2012 Nov 20.

Abstract

Poor local control and tumor escape are of major concern in head-and-neck cancers treated by conventional radiotherapy or hadrontherapy. Reduced glutathione (GSH) is suspected of playing an important role in mechanisms leading to radioresistance, and its depletion should enable oxidative stress insult, thereby modifying the nature of DNA lesions and the subsequent chromosomal changes that potentially lead to tumor escape.This study aimed to highlight the impact of a GSH-depletion strategy (dimethylfumarate, and L-buthionine sulfoximine association) combined with carbon ion or X-ray irradiation on types of DNA lesions (sparse or clustered) and the subsequent transmission of chromosomal changes to the progeny in a radioresistant cell line (SQ20B) expressing a high endogenous GSH content. Results are compared with those of a radiosensitive cell line (SCC61) displaying a low endogenous GSH level. DNA damage measurements (γH2AX/comet assay) demonstrated that a transient GSH depletion in resistant SQ20B cells potentiated the effects of irradiation by initially increasing sparse DNA breaks and oxidative lesions after X-ray irradiation, while carbon ion irradiation enhanced the complexity of clustered oxidative damage. Moreover, residual DNA double-strand breaks were measured whatever the radiation qualities. The nature of the initial DNA lesions and amount of residual DNA damage were similar to those observed in sensitive SCC61 cells after both types of irradiation. Misrepaired or unrepaired lesions may lead to chromosomal changes, estimated in cell progeny by the cytome assay. Both types of irradiation induced aberrations in nondepleted resistant SQ20B and sensitive SCC61 cells. The GSH-depletion strategy prevented the transmission of aberrations (complex rearrangements and chromosome break or loss) in radioresistant SQ20B only when associated with carbon ion irradiation. A GSH-depleting strategy combined with hadrontherapy may thus have considerable advantage in the care of patients, by minimizing genomic instability and improving the local control.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Buthionine Sulfoximine / pharmacology
  • Carbon / chemistry*
  • Cell Cycle Checkpoints / drug effects
  • Cell Cycle Checkpoints / radiation effects
  • Cell Death / drug effects
  • Cell Death / radiation effects
  • Cell Line, Tumor
  • Cell Survival / drug effects
  • Cell Survival / radiation effects
  • Chromatography, High Pressure Liquid
  • Chromosomes, Human / metabolism*
  • Clone Cells
  • Cluster Analysis
  • DNA Breaks, Double-Stranded / drug effects
  • DNA Breaks, Double-Stranded / radiation effects
  • DNA Breaks, Single-Stranded / drug effects
  • DNA Breaks, Single-Stranded / radiation effects
  • DNA Damage*
  • Dimethyl Fumarate
  • Fumarates / pharmacology
  • Gene Rearrangement / drug effects
  • Gene Rearrangement / radiation effects
  • Glutathione / deficiency*
  • Glutathione / metabolism
  • Histones / metabolism
  • Humans
  • Ions
  • Kinetics
  • Micronucleus Tests
  • Neoplasms / metabolism*
  • Neoplasms / pathology*
  • Radiation*
  • X-Rays

Substances

  • Fumarates
  • H2AX protein, human
  • Histones
  • Ions
  • Buthionine Sulfoximine
  • Carbon
  • Dimethyl Fumarate
  • Glutathione

Grants and funding

This research was supported by ETOILE's Research Program through the Regional Programme of Research in Hadrontherapy/Lyon University, under CPER 2007–13 funding and Fondation Synergie Lyon Cancer and Ligue contre le cancer (Ain). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. This does not alter the authors' adherence to all the PLOS ONE policies on sharing data and materials.