Department of Pharmacology, School of Pharmacy, The Fourth Military Medical University, Xi'an 710032, PR China.
Oncol Rep. 2010 Nov;24(5):1297-305. doi: 10.3892/or_00000986.
Docetaxel is a member of the taxane anti-microtubule class of chemotherapeutic agents, which are currently widely used in clinical cancer therapy. However, the anti-tumor mechanisms of docetaxel are not fully understood. Herein we show that docetaxel induces dose-dependent apoptosis in non-small cell lung cancer A549 cells, as detected by Annexin-V positive cells and PARP cleavage, which is via mitochondrial pathway and dependent on caspase-3 activation. Our study on the mechanisms confirms that docetaxel induces dose-dependent accumulation of cells in M phase and acetylation of α-tubulin, marker of tubulin stablization. Furthermore, docetaxel induces replication-dependent γ-H2AX formation which plays a crucial role in docetaxel-triggered apoptosis. The DNA polymerase inhibitor aphidicolin dose-dependently prevents docetaxel-induced γ-H2AX formation, as well as apoptosis. Notably, 0.6 µM APC almost completely blocked docetaxel-induced γ-H2AX formation and apoptosis. In addition, wortmannin pretreatment caused elevated γ-H2AX level, which was accompanied with increased apoptosis. This effect was due to the inhibition of DNA repair process by wortmannin, as down regulation of p21Waf1/Cip1 and DNA repair proteins such as Ku70, Ku80, DNA-PKcs and Rad50, were detected. These data show, for the first time, that the induction of apoptosis by docetaxel requires DNA replication, and replication-mediated DSBs are critical triggers of docetaxel-induced apoptosis.
多西他赛是紫杉烷类抗微管类化疗药物的成员，目前广泛用于临床癌症治疗。然而，多西他赛的抗肿瘤机制尚不完全清楚。本文研究表明，多西他赛诱导非小细胞肺癌 A549 细胞凋亡，通过 Annexin-V 阳性细胞和 PARP 切割检测到，这是通过线粒体途径和 caspase-3 激活依赖性的。我们对机制的研究证实，多西他赛诱导细胞在 M 期和α-微管蛋白乙酰化的剂量依赖性积累，这是微管稳定的标志物。此外，多西他赛诱导复制依赖性γ-H2AX 形成，在多西他赛触发的凋亡中起着至关重要的作用。DNA 聚合酶抑制剂 aphidicolin 剂量依赖性地防止多西他赛诱导的γ-H2AX 形成和凋亡。值得注意的是，0.6µM APC 几乎完全阻断了多西他赛诱导的γ-H2AX 形成和凋亡。此外，wortmannin 预处理导致 γ-H2AX 水平升高，同时凋亡增加。这种效应是由于 wortmannin 抑制 DNA 修复过程，下调 p21Waf1/Cip1 和 DNA 修复蛋白如 Ku70、Ku80、DNA-PKcs 和 Rad50。这些数据首次表明，多西他赛诱导的凋亡需要 DNA 复制，而复制介导的 DSBs 是多西他赛诱导凋亡的关键触发因素。
