MiR-4497 mediates oxidative stress and inflammatory injury in keratinocytes induced by ultraviolet B radiation through regulating NF-κB expression.

BACKGROUND: To investigate the role and underlying mechanism of miR-4497 in oxidative stress and inflammatory injury in keratinocytes induced by ultraviolet B (UVB) radiation.

METHODS: An injury model of keratinocytes induced by UVB radiation was constructed. RT-qPCR, MTT assay and flow cytometry were adopted to detect miR-4497 expression in HaCaT cells, cell proliferation, and cell apoptosis, respectively. The levels of cytokines TNF-α, IL-18, IL-6 and IL-1β in cell culture supernatant were tested by ELISA. ROS levels in the cells were labeled by DCFH-DA fluorescent probe, and then quantitative fluorescence analysis was performed by flow cytometry. SOD activity in the cells was measured by Xanthine Oxidase assay kit. Western blot was used to determine NF-κB expression in cytoplasm and nucleus, and p-IκBα expression in the cells.

RESULTS: UVB radiation significantly increased miR-4497 expression in HaCaT cells, inhibited cell proliferation, and promoted cell apoptosis. Meanwhile, UVB radiation caused the promotion of secretion of cytokines TNF-α, IL-18, IL-6 and IL-1β. The production of reactive oxygen species (ROS) was promoted by UVB radiation, while SOD activity was inhibited. Nuclear transfer of NF-κB signal was also induced by UVB radiation. In addition, downregulation of miR-4497 expression significantly inhibited the effects of UVB radiation on cell proliferation, apoptosis, cytokine secretion, redox level and NF-κB signal in HaCaT cells, while overexpression of miR-4497 further enhanced these effects of UVB radiation on HaCaT cells.

CONCLUSIONS: UVB may promote the expression of inflammatory and oxidative stress signals in keratinocytes by upregulating miR-4497 expression, thus mediating cell injury.