Replication-dependent γ-H2AX formation is involved in docetaxel-induced apoptosis in NSCLC A549 cells.

Abstract

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.

• Authors: Feng Zhang, Tao Zhang, Yang Qu, Tao Jiang, Yun-Xin Cao, Chen Li, Lei Fan, Qi-Bing Mei
• Journal: Oncology reports (Oncol Rep) Vol. 24 Issue 5 Pg. 1297-305 (Nov 2010) ISSN: 1791-2431 [Electronic] Greece
• PMID: 20878124 (Publication Type: Journal Article)

Chemical References

• Antineoplastic Agents
• H2AX protein, human
• Histones
• Taxoids
• Docetaxel
• Caspase 3

Topics

• Antineoplastic Agents (pharmacology)
• Apoptosis (drug effects, genetics)
• Carcinoma, Non-Small-Cell Lung (drug therapy, genetics, pathology)
• Caspase 3 (genetics, metabolism)
• Cell Division (drug effects)
• DNA Breaks, Double-Stranded
• DNA Repair (drug effects)
• DNA Replication (drug effects)
• Docetaxel
• Histones (biosynthesis, genetics, metabolism)
• Humans
• Lung Neoplasms (drug therapy, genetics, metabolism, pathology)
• Taxoids (pharmacology)