Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung 804, Taiwan.
Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung 804, Taiwan; Department of Biotechnology, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
Biochem Pharmacol. 2022 Jan;195:114865. doi: 10.1016/j.bcp.2021.114865. Epub 2021 Dec 2.
Previous studies have confirmed that docetaxel (DTX) treatment increases TNF-α production in cancer cells, but its mechanism of action remains unclear. Therefore, this study aimed to determine the signaling axis by which DTX induced the expression of TNF-α in U937 leukemia and MCF-7 breast carcinoma cells. DTX treatment promoted Ca-controlled autophagy and SIDT2 expression, resulting in lysosomal degradation of miR-25 in U937 cells. Downregulation of miR-25 increased NOX4 mRNA stability and protein expression. NOX4-stimulated ROS generation led to JNK-mediated phosphorylation of cytosolic HuR at Ser221, thereby increasing TNF-α protein expression by stabilizing TNF-α mRNA. Consequently, DTX induced TNF-α-dependent death in U937 cells. Depletion of HuR using siRNA or abolishment of JNK activation reduced TNF-α expression and eliminated DTX-mediated cytotoxicity. Knockdown of SIDT2 or pretreatment with chloroquine (a lysosome inhibitor) reduced DTX-induced NOX4 and TNF-α expression and mitigated JNK-mediated HuR phosphorylation. Altogether, our data indicate that DTX triggers HuR-mediated TNF-α mRNA stabilization through the Ca/SIDT2/NOX4/ROS/JNK axis, thereby inducing TNF-α-dependent apoptosis in U937 cells. In addition, DTX induces apoptosis in MCF-7 cells through SIDT2/NOX4/JNK/HuR axis-mediated TNF-α expression.
先前的研究已经证实，多西紫杉醇（DTX）治疗会增加癌细胞中 TNF-α 的产生，但作用机制尚不清楚。因此，本研究旨在确定 DTX 在 U937 白血病和 MCF-7 乳腺癌细胞中诱导 TNF-α表达的信号轴。DTX 处理促进 Ca 控制的自噬和 SIDT2 表达，导致 U937 细胞中 miR-25 的溶酶体降解。miR-25 的下调增加了 NOX4 mRNA 的稳定性和蛋白表达。NOX4 刺激的 ROS 生成导致 JNK 介导的细胞质 HuR 在 Ser221 上的磷酸化，从而通过稳定 TNF-α mRNA 增加 TNF-α 蛋白表达。因此，DTX 诱导 U937 细胞中 TNF-α 依赖性死亡。使用 siRNA 耗尽 HuR 或消除 JNK 激活可减少 TNF-α 表达并消除 DTX 介导的细胞毒性。SIDT2 的敲低或用氯喹（溶酶体抑制剂）预处理可减少 DTX 诱导的 NOX4 和 TNF-α 表达，并减轻 JNK 介导的 HuR 磷酸化。总之，我们的数据表明，DTX 通过 Ca/SIDT2/NOX4/ROS/JNK 轴触发 HuR 介导的 TNF-α mRNA 稳定，从而诱导 U937 细胞中 TNF-α 依赖性凋亡。此外，DTX 通过 SIDT2/NOX4/JNK/HuR 轴介导的 TNF-α 表达诱导 MCF-7 细胞凋亡。
