UVB radiation induces an increase in intracellular zinc in human epidermal keratinocytes

作者：Stork Christian J; Martorano Lisa M; Li Yang V^*

来源：International Journal of Molecular Medicine, 2010, 26(4): 463-469.

DOI：10.3892/ijmm_00000486

• zinc
• cell death
• ultraviolet
• keratinocytes
• skin
• cytotoxicity
• Newport Green

Ultraviolet (UV) radiation is known to cause oxidative stress, inflammation, DNA damage and apoptotic cell death; however, many details of these malign mechanism have yet to be elucidated. In this study, the exposure of adult human epidermal keratinocytes (HEKa) with UVB (>100 mJ/cm(2)) resulted in the significant increase of intracellular zinc that was released from its storage and was detected by fluorescent zinc indicators. Toxicity testing revealed that UVB-induced zinc release in HEKa is associated with HEKa cell death. Cells that showed elevated intracellular zinc fluorescence upon UVB exposure were also stained by propidium iodide (PI), a traditional viability indicator whose fluorescent signal is as a result of its intercalating with DNA fragments and is unaffected by zinc concentration, showing significant colocalization [Pearson's correlation coefficients r=0.956 (n=6)]. The cytotoxicity of zinc was also determined by an MTT assay after applying the exogenous zinc (ZnCl2) along with its ionophore pyrithione (20 yM) into HEKa culture medium. A significant reduction in cell viability as a function of both zinc concentration and exposure time was observed. The treatments of 1, 10 and 100 mu M ZnCl2 with pyrithione demonstrated 2.3, 60 and 84% cell deaths, respectively (control 0.5%) after 30 min. ZnCl2 (100 mu M) was also found to induce complete HEKa death after 1 h. Thus, the present study demonstrates that UVB irradiation-induced increased zinc is detrimental to HEKa viability, and zinc may be a necessary step in UVB-induced cell death signaling pathways.

• 出版日期2010-10