Tolerance for UV stress in human epidermal keratinocytes

Cell death or canceration of skin cells is caused by cell damage or DNA damage by irradiation of ultraviolet light. When epidermal keratinocytes, which present in the outermost layer of the skin, are exposed to UVB stress, their cell death or canceration causes cell barrier injury, eventually leading various skin diseases. To antagonize such an ultraviolet irradiation injury, heat shock protein (HSP70) can work. It has been so far reported that HSP70 was induced by heat shock, promoting the DNA repair and preventing cell death.

Recently, there was a report that near-infrared irradiation prevented cell death by ultraviolet light in human fibroblasts, suggesting that HSP70 was involved in this mechanism. However, the exact results have not yet been obtained.

In our study, we hypothesized that when human epidermal keratinocytes are irradiated with near-infrared light, the expression of HSP70 is induced, and then cell death and DNA damage are prevented. We are now attempting to prove this hypothesis.