Abstract:

Objective To investigate the role of activation of Akt/mTOR pathway in denfense against UVB-induced apoptosis in cultured human skin keratinocyte cell line HaCaT. Methods HaCaT cells were irradiated with UVB at different doses for various durations. Western blotting was performed to detect dynamic changes of Akt/mTOR pathway-related signaling molecule, such as phosphorylated-epidermal growth factor receptor （EGFR）, -Akt, -4EBP1, etc; apoptosis was estimated by staining with DNA dye Hoechst 33342. To evaluate the role of signaling molecules in defense against UVB-induced apoptosis, HaCaT cells were pretreated before irradiation with EGFR inhibitor （PD153035）, PI3K inhibitor （LY294002）, mTOR inhibitor （rapamycin） followed by the detection of expressions of signaling molecule and apoptosis. Results UVB could activate Akt/mTOR pathway in a dose- （5 ~ 30 mJ/cm2） and time- （5 ~ 30 min） dependent manner. PD153035, LY 294002 and rapamycin could inhibit UVB-induced activation of the Akt/mTOR pathway. The apoptosis rate in HaCaT cells was upregulated by pretreatment with rapamycin and LY294002. Conclusion The activation of Akt/mTOR signaling pathway could inhibit the UVB-induced apoptosis in cultured HaCaT cells.

Key words: Ultraviolet rays, Keratinocytes, Signal transduction