Efeitos de LED azul e laser vermelho de baixa potência na sobrevivência celular e expressão gênica de fotoliases em culturas de Escherichia coli e da viabilidade celular e expressão de genes circadianos em células de câncer de mama

Abstract

Therapeutic low-power LEDs and lasers are used based on photobiomodulation, but the photobiomodulation effects on DNA repair mechanisms in bacterial cells and the expression of circadian genes in mammalian tumor cells have not yet been explored. Thus, the objective of this work was to evaluate the effects of low-power therapeutic blue LED and red laser on the genes of the flavoprotein family by prokaryotic and eukaryotic models. Aliquots of plasmid pUC19 and cultures of E. coli C600, MCF-7 and MDA-MB-231 were exposed to blue LED (470 nm) and red laser (658 nm) at different fluences. Other cultures of E. coli C600 were exposed to UVC radiation, followed by low-power blue LEDs and red laser. After irradiation, plasmids were subjected to agarose gel electrophoresis to evaluate the plasmidial forms, bacterial cultures were spread on petri dishes containing nutritive medium to evaluate the bacterial survival and proliferation, and photolyase mRNA levels of bacterial cells were assessed by real-time quantitative polymerase chain reaction. Cultures of MCF-7 and MDA-MB-231, after irradiation, were also cultivated in DMEM and RPMI medium, respectively, supplemented with fetal bovine serum. The mRNA levels of circadian genes were also assessed by real-time quantitative polymerase chain reaction. The cell viability assay by WST-1 was performed at 24, 48 and 72 hours after irradiation. The results suggest that exposure to low-power blue LED and red laser do not cause DNA strand breaks in bacterial plasmids and do not alter survival and the mRNA levels of the photolyase gene in E. coli cells, but increase survival and proliferation in E. coli cultures exposed to ultraviolet C radiation depending on the laser fluence. The cell viability and the mRNA levels of the circadian genes in MCF-7 and MDA-MB-231 cells after exposure to low-power blue LED and red laser did not change in evaluated fluences.