title: Glutathione depletion and carbon ion radiation potentiate clustered DNA lesions, cell death and prevent chromosomal changes in cancer cells progeny.
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.
authors.affiliation: Laboratoire de Radiobiologie Cellulaire et Moléculaire, EMR3738, Faculté de Médecine Lyon-Sud, Oullins, France.
authors.forename: Maïté
authors.initials: M
authors.lastname: Hanot
authors.forename: Anthony
authors.initials: A
authors.lastname: Boivin
authors.forename: Céline
authors.initials: C
authors.lastname: Malésys
authors.forename: Michaël
authors.initials: M
authors.lastname: Beuve
authors.forename: Anthony
authors.initials: A
authors.lastname: Colliaux
authors.forename: Nicolas
authors.initials: N
authors.lastname: Foray
authors.forename: Thierry
authors.initials: T
authors.lastname: Douki
authors.forename: Dominique
authors.initials: D
authors.lastname: Ardail
authors.forename: Claire
authors.initials: C
authors.lastname: Rodriguez-Lafrasse
mesh_terms: D019328:Buthionine Sulfoximine / Q000494:pharmacology; D002244:Carbon / Q000737:chemistry*; D059447:Cell Cycle Checkpoints / Q000187:drug effects / Q000528:radiation effects; D016923:Cell Death / Q000187:drug effects / Q000528:radiation effects; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D002851:Chromatography, High Pressure Liquid; D002877:Chromosomes, Human / Q000378:metabolism*; D002999:Clone Cells; D016000:Cluster Analysis; D053903:DNA Breaks, Double-Stranded / Q000187:drug effects / Q000528:radiation effects; D053904:DNA Breaks, Single-Stranded / Q000187:drug effects / Q000528:radiation effects; D004249:DNA Damage; D000069462:Dimethyl Fumarate; D005650:Fumarates / Q000494:pharmacology; D015321:Gene Rearrangement / Q000187:drug effects / Q000528:radiation effects; D005978:Glutathione / Q000172:deficiency* / Q000378:metabolism; D006657:Histones / Q000378:metabolism; D006801:Humans; D007477:Ions; D007700:Kinetics; D015162:Micronucleus Tests; D009369:Neoplasms / Q000378:metabolism* / Q000473:pathology*; D011827:Radiation; D014965:X-Rays
chemical_list: D005650:Fumarates; C468783:H2AX protein, human; D006657:Histones; D007477:Ions; D019328:Buthionine Sulfoximine; D002244:Carbon; D000069462:Dimethyl Fumarate; D005978:Glutathione