Department of Toxicology, School of Public Health, Jiangsu Key Laboratory of Preventive and Translational Medicine for Geriatric Diseases, Medical College of Soochow University, Suzhou 215123, Jiangsu, China.
Laboratory of Environmental Toxicology and Carcinogenesis, School of Pharmacy, Nihon University, Chiba, Japan.
Sci Total Environ. 2020 Sep 10;734:139425. doi: 10.1016/j.scitotenv.2020.139425. Epub 2020 May 13.
Autophagy dysfunction in arsenite toxicity plays critical roles in cancer development and progression. However, the precise mechanisms of arsenite-induced skin cancer by blocking autophagy remain uncertain. Herein, this study investigated molecular mechanisms of arsenite-induced autophagy dysfunction mediated by nuclear factor erythroid-2 related factor 2 (Nrf2) in human keratinocyte (HaCaT) cells. The effects of long-term arsenite exposure on Nrf2 activation and autophagy were established using a siRNA interference assay and western blots. A specific siRNA of Nrf2 was used to verify that autophagy induced by arsenite can be influenced by Nrf2. Specific inhibitors of PI3K (LY294002) and mTOR (Rapamycin) and siRNA of Nrf2 were employed to verify that upregulation of Nrf2 correlated with activating the PI3K/Akt pathway. Downstream mTOR and Bcl2 were upregulated by Nrf2 signaling, inhibiting autophagy initiation in arsenite-exposed HaCaT cells. In conclusion, our data suggest that long-term exposure to arsenite promotes Nrf2 upregulation via the PI3K/Akt pathway and, along with upregulation of downstream mTOR and Bcl2, contributes to autophagy dysfunction in transformed HaCaT cells. This work provides new insights into the mechanisms underlying arsenite-induced autophagy dysfunction in cancer promotion and malignancy progression.
砷化物毒性中的自噬功能障碍在癌症的发生和发展中起着关键作用。然而，通过阻断自噬来抑制砷化物诱导皮肤癌的确切机制尚不清楚。本研究探讨了核因子红细胞 2 相关因子 2（Nrf2）介导的砷化物诱导的人角质形成细胞（HaCaT）细胞自噬功能障碍的分子机制。采用 siRNA 干扰试验和 Western blot 法建立了长期砷暴露对 Nrf2 激活和自噬的影响。使用 Nrf2 的特异性 siRNA 验证了砷化物诱导的自噬可以受到 Nrf2 的影响。PI3K（LY294002）和 mTOR（雷帕霉素）的特异性抑制剂和 Nrf2 的 siRNA 用于验证 Nrf2 的上调与激活 PI3K/Akt 途径有关。下游的 mTOR 和 Bcl2 被 Nrf2 信号上调，抑制了砷化物暴露的 HaCaT 细胞中自噬的起始。总之，我们的数据表明，长期暴露于砷化物通过 PI3K/Akt 途径促进 Nrf2 的上调，并且与下游 mTOR 和 Bcl2 的上调一起，导致转化的 HaCaT 细胞中的自噬功能障碍。这项工作为砷化物诱导的自噬功能障碍在癌症促进和恶性进展中的机制提供了新的见解。
