Department of Respiratory Medicine, Kanazawa University, Ishikawa, Japan
Department of Respiratory Medicine, Kanazawa University, Ishikawa, Japan.
Cancer Genomics Proteomics. 2021 Sep-Oct;18(5):645-659. doi: 10.21873/cgp.20287.
BACKGROUND/AIM: Paclitaxel is used as a first-line and subsequent therapy for the treatment of various cancers. However, the function and mechanisms of action of paclitaxel in non-small-cell lung cancer (NSCLC) remain unknown. In this study, the molecular mechanism underlying the anticancer activity of paclitaxel was investigated in vitro in a human NSCLC cell line carrying the EGFR exon 19 deletion (PC9).
PC9 cells were treated with paclitaxel and then evaluated with a cell viability assay, DAPI staining, Giemsa staining, apoptosis assay, reactive oxygen species (ROS) assay, terminal deoxynucleotidyl transferase dUTP nick-end labeling assay and Western blotting.
Paclitaxel markedly decreased the viability of PC9 cells and induced morphological signs of apoptosis. The apoptotic effects of paclitaxel were observed through caspase cascade activation, along with ROS generation and loss of mitochondrial membrane potential (MMP). Furthermore, paclitaxel induced ROS-mediated DNA damage that triggered the activation of the extrinsic pathway of apoptosis via the up-regulation of death receptor (DR5) and caspase-8 activation. In addition, we found that paclitaxel effectively suppressed the EGFR/PI3K/AKT/mTOR signaling pathway to impede PC9 cell growth. Paclitaxel induced cell cycle arrest at the G1 phase in response to DNA damage, in association with the suppression of CDC25A, Cdk2 and Cyclin E1 protein expression.
Paclitaxel showed anticancer effects against NSCLC by activating extrinsic and intrinsic apoptotic pathways through enhancing ROS generation, inducing cell cycle arrest, and suppressing EGFR/PI3K/AKT/mTOR signaling pathway.
背景/目的：紫杉醇被用作治疗各种癌症的一线和后续治疗药物。然而，紫杉醇在非小细胞肺癌（NSCLC）中的作用和机制尚不清楚。在这项研究中，我们在携带 EGFR 外显子 19 缺失（PC9）的人 NSCLC 细胞系中体外研究了紫杉醇的抗癌活性的分子机制。
用紫杉醇处理 PC9 细胞，然后通过细胞活力测定、DAPI 染色、吉姆萨染色、凋亡测定、活性氧（ROS）测定、末端脱氧核苷酸转移酶 dUTP 缺口末端标记测定和 Western blot 进行评估。
紫杉醇显著降低 PC9 细胞的活力并诱导凋亡的形态学迹象。通过 caspase 级联激活观察到紫杉醇的凋亡作用，同时伴随着 ROS 的产生和线粒体膜电位（MMP）的丧失。此外，紫杉醇诱导 ROS 介导的 DNA 损伤，通过上调死亡受体（DR5）和 caspase-8 的激活触发凋亡的外源性途径的激活。此外，我们发现紫杉醇有效地抑制了 EGFR/PI3K/AKT/mTOR 信号通路，以阻止 PC9 细胞生长。紫杉醇通过抑制 CDC25A、Cdk2 和 Cyclin E1 蛋白表达，导致细胞周期在 G1 期停滞，从而对 DNA 损伤产生反应。
紫杉醇通过增强 ROS 的产生、诱导细胞周期停滞以及抑制 EGFR/PI3K/AKT/mTOR 信号通路，通过激活外源性和内源性凋亡途径对 NSCLC 表现出抗癌作用。
