Dramatic Increase in Oxidative Stress in Carbon-Irradiated Normal Human Skin Fibroblasts

Abstract

Skin complications were recently reported after carbon-ion (C-ion) radiation therapy. Oxidative stress is considered an important pathway in the appearance of late skin reactions. We evaluated oxidative stress in normal human skin fibroblasts after carbon-ion vs. X-ray irradiation. Survival curves and radiobiological parameters were calculated. DNA damage was quantified, as were lipid peroxidation (LPO), protein carbonylation and antioxidant enzyme activities. Reduced and oxidized glutathione ratios (GSH/GSSG) were determined. Proinflammatory cytokine secretion in culture supernatants was evaluated. The relative biological effectiveness (RBE) of C-ions vs. X-rays was 4.8 at D0 (irradiation dose corresponding to a surviving fraction of 37%). Surviving fraction at 2 Gy (SF2) was 71.8% and 7.6% for X-rays and C-ions, respectively. Compared with X-rays, immediate DNA damage was increased less after C-ions, but a late increase was observed at D10% (irradiation dose corresponding to a surviving fraction of 10%). LPO products and protein carbonyls were only increased 24 hours after C-ions. After X-rays, superoxide dismutase (SOD) activity was strongly increased immediately and on day 14 at D0% (irradiation dose corresponding to a surviving fraction of around 0%), catalase activity was unchanged and glutathione peroxidase (GPx) activity was increased only on day 14. These activities were decreased after C-ions compared with X-rays. GSH/GSSG was unchanged after X-rays but was decreased immediately after C-ion irradiation before an increase from day 7. Secretion of IL-6 was increased at late times after X-ray irradiation. After C-ion irradiation, IL-6 concentration was increased on day 7 but was lower compared with X-rays at later times. C-ion effects on normal human skin fibroblasts seemed to be harmful in comparison with X-rays as they produce late DNA damage, LPO products and protein carbonyls, and as they decrease antioxidant defences. Mechanisms leading to this discrepancy between the two types of radiation should be investigated.

Comparable Senescence Induction in Three-dimensional Human Cartilage Model by Exposure to Therapeutic Doses of X-rays or C-ions

“…Moreover, a putative interindividual variability in radiosensitivity between human cell donors could explain in part such a discrepancy between studies. The RBE (D 10 ) calculated from our data (2.6) was rather smaller than that found with normal human fibroblasts (3.29) in our laboratory using the same irradiation facility (30). However, it was in the range of a previously published database consisting in 855 in vitro survival experiments after ion and photon irradiation (31).…”

Production of early and late nuclear DNA damage and extracellular 8-oxodG in normal human skin fibroblasts after carbon ion irradiation compared to X-rays

“…In particular, Yanagi et al (2010) reported severe acute and late skin complications on patients treated for unresectable bone and soft tissue sarcoma by a C-ion dose escalation protocol. We have recently reported that skin fibroblasts showed a stronger increase in oxidative stress after C-ion vs Xray irradiation, even at late times -two weeks -after in vitro irradiation (Laurent et al, 2013).…”

HIF-1α and rapamycin act as gerosuppressant in multiple myeloma cells upon genotoxic stress

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