Photobiomodulation Therapy Minimizes the DNA Damage in 5FU‐Treated Gingival Fibroblasts

ABSTRACT 5‐Fluoroufacil (5FU) is a chemotherapeutic agent indicated for solid tumors but causes oral mucositis, which can be prevented and treated using photobiomodulation therapy (PBMT). It is unknown whether PBMT modifies DNA damage induced by 5FU in oral cells. The aim of this study was to investigate the effect of PBMT on DNA damage and repair and on oxidative stress in gingival fibroblasts exposed to 5FU. Primary gingival fibroblasts were exposed to 5FU and then treated with a laser (660 nm, 100 mW, 1 W cm−2, 0.09 cm2 spot area) for three different irradiation times (6, 10 or 20 s). Six‐second irradiation decreased DNA damage and lipidic peroxidation. All irradiated groups showed low H2AX levels and increased p53 expression. Ten‐second irradiation showed a trend to induce high lipidic peroxidation levels and DNA damage than other irradiation groups. In conclusion, the PBMT effect on DNA damage and repair was dependent on the time irradiation: 6 s‐time irradiation (6.6 J cm−2) protect gingival fibroblasts from 5FU‐related genotoxicity and oxidative stress, whereas 10s‐ and 20s‐time irradiations (11.1 J cm−2 and 22.2 J cm−2, respectively) increased the risk of DNA damage after the 5FU exposure. Comet assay showing a DNA tail in 5FU‐treated cells greater than those noted in 5‐FU treated cells exposed to photobiomodulation (6 J cm−2).