Effects of low-power infrared laser and amber LED on cell viability and reactive oxygen species levels in human breast cancer cells

Abstract Low-power lasers and LEDs (light-emitting diodes) have been used to induce photobiomodulation (PBM) based on therapeutic protocols to treat diseases and clinical conditions. PBM begins with the absorption of radiation by photoacceptors, generating trigger molecules, such as reactive oxygen species (ROS), which leads to molecular, cellular and systemic effects. Breast cancer (BC) is the main cause of cancer death among women, and treatment depends on BC subtype. Despite the PBM being considered safe, its applications on cancer patients are controversial, which could hinder the benefits of PBM on BC patients. Thus, this study aimed to evaluate the effects of a low-power infrared laser and an amber LED on cell viability and ROS levels in human BC triple-negative and luminal A cells. For that, MDA-MB-231 and MCF-7 cultures were exposed to infrared laser (830 nm; 150 mW; 1.19 W cm −2 ; 32, 64, and 97 J cm −2 ) and amber LED (617 nm; 1500 mW; 11.94 W cm −2 ; 358, 716, and 1074 J cm −2 ), alone and simultaneously, and cell viability was evaluated. Also, ROS levels were evaluated by flow cytometry. The results show that exposure to low-power infrared laser and amber LED does not alter the cell viability in MDA-MB-231 and MCF-7 cultures. However, exposure to simultaneous infrared laser and amber LED increases ROS generation in MCF-7 cells. These results suggest that the effects of PBM induced by simultaneous exposure to low-power radiations on redox state depend on the human BC cell subtype.