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.
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ABSTRACT: Histone's H2A variant (H2AX) phosphorylation is an early indicator of DNA double-strand breaks formation and DNA damage response. Thus, it may act as a novel biomarker to monitor genotoxic events that can drive cancer development and tumor progression. This review will focus on the possible applications of H2AX as a key regulator of DNA damage response in lung cancer and as a biomarker of: sensitivity of lung tumors to chemotherapy and radiotherapy, treatment with PARP inhibitors, bystander effect, multistep lung carcinogenesis, environmental smoking, and chemical genotoxicity, chemoprevention, prognosis, and also as therapeutic targets in lung cancers.Cancer Investigation 11/2013; 31(9):582-99. DOI:10.3109/07357907.2013.849721 · 2.06 Impact Factor
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ABSTRACT: Colorectal cancer is a common cancer worldwide, and chemotherapy is a mainstream approach for advanced and recurrent cases. Development of effective complementary drugs could help improve tumor suppression efficiency and control adverse effects from chemotherapy. The aqueous extract of Solanum nigrum leaves (AE-SN) is an essential component in many traditional Chinese medicine formulas for treating cancer, but there is a lack of evidence verifying its tumor suppression efficacy in colorectal cancer. The purpose of this study is to evaluate the tumor suppression efficacy of AE-SN using DLD-1 and HT-29 human colorectal carcinoma cells and examine the combined drug effect when combined with the chemotherapeutic drugs cisplatin, doxorubicin, docetaxel, and 5-fluorouracil. The results indicated that AE-SN induced autophagy via microtubule-associated protein 1 light chain 3 A/B II accumulation but not caspase-3-dependent apoptosis in both cell lines. The IC50s after 48 hours of treatment were 0.541 and 0.948 mg/ml AE-SN in DLD-1 and HT-29, respectively. AE-SN also demonstrated a combined drug effect with all tested drugs by enhancing cytotoxicity in tumor cells. Our results suggest that AE-SN has potential in the development of complementary chemotherapy for colorectal cancer.Evidence-based Complementary and Alternative Medicine 06/2013; 2013:514719. DOI:10.1155/2013/514719 · 2.18 Impact Factor
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ABSTRACT: Chemotherapy is the main approach in dealing with advanced and recurrent endometrial cancer. An effective complementary ingredient can be helpful in improving the clinical outcome. Aqueous extract of Solanum nigrum leaf (AE-SN) is a principal ingredient for treating cancer patients in traditional Chinese medicinal practice but lacks sufficient evidence to verify its tumor suppression efficacy. This study evaluated the antitumor effects of AE-SN and also assessed the synergistic effects of AE-SN with docetaxel On the human endometrial cancer cell lines, HEC1A, HEC1B, and KLE. The activation of apoptotic markers, caspase-3 and poly-ADP-ribose polymerase, and autophagic marker, microtubule-associated protein 1 light chain 3 A/B, wAS determined to clarify the cell death pathways responsible for AE-SN induced tumor cell death. Results indicated that AE-SN-treatment has significant cytotoxicity on the tested endometrial cancer cells with accumulation of LC3 A/B II and demonstrated a synergistic effect of AE-SN and docetaxel in HEC1A and HEC1B cells, but not KLE cells. In conclusion, AE-SN treatment was effective in suppressing endometrial cancer cells via the autophagic pathway and was also capable of enhancing the cytotoxicity of docetaxel in human endometrial cancer cells. Our results provide meaningful evidence for integrative cancer therapy in the future.Evidence-based Complementary and Alternative Medicine 11/2012; 2012:859185. DOI:10.1155/2012/859185 · 2.18 Impact Factor