Endoplasmic Reticulum Stress Is Involved In The NaAsO₂-Induced Apoptosis In HaCaT Cells

Objective:Arsenic is a natural element that is ubiquitous in the environment in both organic and inorganic forms.It is one of WHO’s recognized carcinogens.Long-term exposure to arsenic can lead to a variety of chronic diseases,such as the nervous system,cardiovascular,cerebrovascular and respiratory diseases.It can also lead to a variety of hyperkeratinization and depigmentation skin diseases,furthermore,skin tumor,such as squamous cell carcinoma,basal cell carcinoma and Bowen’s disease.At present,more studies explored arsenic and skin diseases,but the specific mechanism is still not clear.In recent years,with the progress of endoplasmic reticulum stress research,it has found that excessive endoplasmic reticulum stress can lead to apoptosis.But it not yet clear that endoplasmic reticulum stress is involved in arsenic-induced cutancous cell apoptosis.The aim of this study was to find the role of endoplasmic reticulum stress in arsenic-induced HaCaT cell apoptosis by investigate the relationship between the expression of PERK,Bcl-2 and Bax and the number of HaCaT cells,thus provided a better understanding of arsenic toxicity.Methods:In this study,we treat HaCaT cells with NaAsO₂ for 24h.The HaCaT cell viability was test by MTT assay.We choose the Westernt blot to test the changing of the expression level of anti-apoptotic protein（Bcl-2）,pro-apoptotic protein（Bax）.Cell apoptosis was observed by TUNEL staining under a fluorescence microscope.After knockdown of the PERK by siRNA PERK,we detect the changing of the experimental index measured by the methods mentioned above respectively.Results:We found that under 1.25μM concentration NaAsO₂,the viability of HaCaT cell was increased and under other concentration,the viability decreased.After treated with 1.25μM,2.5μM and 5μM concentration NaAsO₂ for 24h,the expression level of Bcl-2 protein decreased,and Bax protein increased in HaCaT cell.The percentage of apoptotic cells observed by TUNEL also increased.At the same time,we found that the expression level of phosphorylated PERK（one of the marker proteins in ERS）protein increased as the increase of NaAsO₂.Compared with the negative control group,the expression level of Bcl-2 protein increased and Bax protein,decreased in HaCaT cells and the percentage of apoptotic cells observed by TUNEL also decreased after pretreated with siRNA against PERK.Conclusion:We demonstrated that NaAsO₂ induced apoptosis of HaCaT cells,and induced ERS in HaTaT cells.ERS mediated NaAsO₂-induced HaCaT cell apoptosis.