DNA Repair Activation and Cell Death Suppression by Plant Polyphenols in Keratinocytes Exposed to Ultraviolet Irradiation.

This work investigated effects of plant polyphenolic compounds (PPs) on responses of cultured human HaCaT keratinocytes to ultraviolet radiation in the C range (UV-C). The experimental data obtained indicate a cytoprotective effect of PPs added immediately after UV-C exposure. The efficiency of PPs was lowered in the following order: acacetin ≥ silybin > quercetin. The influence of PPs on phosphorylation of histone H2AX and the number of single-strand DNA breaks in the nuclei of keratinocytes were also studied. Using the comet assay and γH2AX staining, followed by fluorescence microscopy, it has been established that PPs can reduce DNA damage in the nuclei of keratinocytes exposed to UV-C. It is concluded that PPs can diminish the destructive effect of UV radiation on skin cells, activating the process of repairing genetic damage.

Effects of minocycline and rapamycin in gamma-irradiated human embryonic stem cells-derived cerebral organoids.

Radiation induces DNA and protein damage and free radical formation, effectively establishing cellular senescence in a variety of models. We demonstrate the effects of two known pleiotropic drugs following gamma radiation damage in neurosphere/cerebral organoid system based on human embryonic stem cells. mTORC1 repression by rapamycin prior to irradiation, or metabolic activation by minocycline after irradiation, partially rescues neuroepithelium integrity, neurite-growing capacity, ventricle formation and extracellular acidification rate as an integral measure of metabolic output. Cerebral organoid model thus provides valid and robust readouts for radiation studies in a complex 3D setting.