title: 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.affiliation: Department of Pharmacology, School of Pharmacy, The Fourth Military Medical University, Xi'an 710032, PR China.
authors.forename: Feng
authors.initials: F
authors.lastname: Zhang
authors.forename: Tao
authors.initials: T
authors.lastname: Zhang
authors.forename: Yang
authors.initials: Y
authors.lastname: Qu
authors.forename: Tao
authors.initials: T
authors.lastname: Jiang
authors.forename: Yun-Xin
authors.initials: YX
authors.lastname: Cao
authors.forename: Chen
authors.initials: C
authors.lastname: Li
authors.forename: Lei
authors.initials: L
authors.lastname: Fan
authors.forename: Qi-Bing
authors.initials: QB
authors.lastname: Mei
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D053148:Caspase 3 / Q000235:genetics / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair / Q000187:drug effects; D004261:DNA Replication / Q000187:drug effects; D000077143:Docetaxel; D006657:Histones / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D043823:Taxoids / Q000494:pharmacology*
chemical_list: D000970:Antineoplastic Agents; C468783:H2AX protein, human; D006657:Histones; D043823:Taxoids; D000077143:Docetaxel; D053148:Caspase 3