Department of Predictive Toxicology, Korea Institute of Toxicology, 141 Gajeong-ro, Yuseong-gu, Daejeon, 34114, Republic of Korea; Bio Medical Research Center, Bio Medical & Health Division, Korea Testing Laboratory (KTL), Seoul, 08389, Republic of Korea.
Department of Predictive Toxicology, Korea Institute of Toxicology, 141 Gajeong-ro, Yuseong-gu, Daejeon, 34114, Republic of Korea; Department of Human and Environmental Toxicology, University of Science & Technology, Daejeon, 34113, Republic of Korea.
Toxicol Lett. 2021 May 15;342:73-84. doi: 10.1016/j.toxlet.2021.02.009. Epub 2021 Feb 17.
Trovafloxacin (TVX) is associated with idiosyncratic drug-induced liver injury (iDILI) and inflammation-mediated hepatotoxicity. However, the inflammatory stress-regulated mechanisms in iDILI remain unclear. Herein, we elucidated the novel role of tumor-necrosis factor alpha (TNFα), an inflammatory stress factor, in TVX-induced in vitro hepatotoxicity and synergistic toxicity. TVX specifically induced synergistic toxicity in HepG2 cells with TNFα, which inhibits autophagy. TVX-treated HepG2 cells induced protective autophagy by inhibiting the expression of mTOR signaling proteins, while ATG5 knockdown in HepG2 cells, responsible for the impairment of autophagy, enhanced TVX-induced toxicity due to the increase in cytochrome C release and JNK pathway activation. Interestingly, the expression of mTOR signal proteins, which were suppressed by TVX, disrupted the negative feedback of the PI3K/AKT pathway and TNFα rebounded p70S6K phosphorylation. Co-treatment with TVX and TNFα inhibited protective autophagy by maintaining p70S6K activity, which enhanced TVX-induced cytotoxicity. Phosphorylation of p70S6K was inhibited by siRNA knockdown and rapamycin to restore TNFα-inhibited autophagy, which prevented the synergistic effect on TVX-induced cytotoxicity. These results indicate that TVX activates protective autophagy in HepG2 cells exposed to toxicity and an imbalance in negative feedback regulation of autophagy by TNFα synergistically enhanced the toxicity. The finding from this study may contribute to a better understanding of the mechanisms underlying iDILI associated with inflammatory stress.
曲伐沙星（TVX）与特异质药物诱导的肝损伤（iDILI）和炎症介导的肝毒性有关。然而，iDILI 中炎症应激调节的机制尚不清楚。在此，我们阐明了肿瘤坏死因子α（TNFα）作为炎症应激因子在 TVX 诱导的体外肝毒性和协同毒性中的新作用。TVX 特异性地与 TNFα 一起诱导 HepG2 细胞产生协同毒性，TNFα 抑制自噬。TVX 处理的 HepG2 细胞通过抑制 mTOR 信号蛋白的表达诱导保护性自噬，而负责自噬损伤的 ATG5 在 HepG2 细胞中的敲低由于细胞色素 C 释放增加和 JNK 途径激活，增强了 TVX 诱导的毒性。有趣的是，被 TVX 抑制的 mTOR 信号蛋白的表达破坏了 PI3K/AKT 通路的负反馈，TNFα 使 p70S6K 磷酸化反弹。TVX 和 TNFα 的共同处理通过维持 p70S6K 活性来抑制保护性自噬，从而增强了 TVX 诱导的细胞毒性。通过 siRNA 敲低和 rapamycin 抑制 p70S6K 的磷酸化，恢复 TNFα 抑制的自噬，防止了对 TVX 诱导的细胞毒性的协同作用。这些结果表明，TVX 在暴露于毒性的 HepG2 细胞中激活保护性自噬，而 TNFα 对自噬的负反馈调节失衡则协同增强了毒性。本研究的结果可能有助于更好地理解与炎症应激相关的 iDILI 的机制。
