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Thorne D, Larard S, Baxter A, Meredith C, Gaҫa M. The comparative in vitro assessment of e-cigarette and cigarette smoke aerosols using the γH2AX assay and applied dose measurements. Toxicol Lett 2016; 265:170-178. [PMID: 27965004 DOI: 10.1016/j.toxlet.2016.12.006] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Revised: 12/02/2016] [Accepted: 12/07/2016] [Indexed: 11/17/2022]
Abstract
DNA damage can be caused by a variety of external and internal factors and together with cellular responses, can establish genomic instability through multiple pathways. DNA damage therefore, is considered to play an important role in the aetiology and early stages of carcinogenesis. The DNA-damage inducing potential of tobacco smoke aerosols in vitro has been extensively investigated; however, the ability of e-cigarette aerosols to induce DNA damage has not been extensively investigated. E-cigarette use has grown globally in recent years and the health implications of long term e-cigarette use are still unclear. Therefore, this study has assessed the induction of double-strand DNA damage in vitro using human lung epithelial cells to e-cigarette aerosols from two different product variants (a "cigalike" and a closed "modular" system) and cigarette smoke. A Vitrocell® VC 10 aerosol exposure system was used to generate and dilute cigarette smoke and e-cigarette aerosols, which were delivered to human bronchial epithelial cells (BEAS-2Bs) housed at the air-liquid-interface (ALI) for up to 120min exposure (diluting airflow, 0.25-1L/min). Following exposure, cells were immediately fixed, incubated with primary (0.1% γH2AX antibody in PBS) and secondary antibodies (DyLight™ 549 conjugated goat anti-mouse IgG) containing Hoechst dye DNA staining solution (0.2% secondary antibody and 0.01% Hoechst in PBS), and finally screened using the Cellomics Arrayscan VTI platform. The results from this study demonstrate a clear DNA damage-induced dose response with increasing smoke concentrations up to cytotoxic levels. In contrast, e-cigarette aerosols from two product variants did not induce DNA damage at equivalent to or greater than doses of cigarette smoke aerosol. In this study dosimetry approaches were used to contextualize exposure, define exposure conditions and facilitate comparisons between cigarette smoke and e-cigarette aerosols. Quartz crystal microbalance (QCM) technology and quantified nicotine delivery were both assessed at the exposure interface. Nicotine was eluted from the QCM surface to give a quantifiable measure of exposure to support deposited mass. Dose measured as deposited mass (μg/cm2) and nicotine (ng/mL) demonstrated that in vitro e-cigarette exposures were conducted at doses up to 12-28 fold to that of cigarette smoke and demonstrated a consistent negative finding.
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Affiliation(s)
- David Thorne
- British American Tobacco, R&D Centre, Southampton, Hampshire, SO15 8TL, UK.
| | - Sophie Larard
- British American Tobacco, R&D Centre, Southampton, Hampshire, SO15 8TL, UK
| | - Andrew Baxter
- British American Tobacco, R&D Centre, Southampton, Hampshire, SO15 8TL, UK
| | - Clive Meredith
- British American Tobacco, R&D Centre, Southampton, Hampshire, SO15 8TL, UK
| | - Marianna Gaҫa
- British American Tobacco, R&D Centre, Southampton, Hampshire, SO15 8TL, UK
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102
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The Role of Deoxycytidine Kinase (dCK) in Radiation-Induced Cell Death. Int J Mol Sci 2016; 17:ijms17111939. [PMID: 27879648 PMCID: PMC5133934 DOI: 10.3390/ijms17111939] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Revised: 10/12/2016] [Accepted: 11/14/2016] [Indexed: 12/26/2022] Open
Abstract
Deoxycytidine kinase (dCK) is a key enzyme in deoxyribonucleoside salvage and the anti-tumor activity for many nucleoside analogs. dCK is activated in response to ionizing radiation (IR)-induced DNA damage and it is phosphorylated on Serine 74 by the Ataxia-Telangiectasia Mutated (ATM) kinase in order to activate the cell cycle G2/M checkpoint. However, whether dCK plays a role in radiation-induced cell death is less clear. In this study, we genetically modified dCK expression by knocking down or expressing a WT (wild-type), S74A (abrogates phosphorylation) and S74E (mimics phosphorylation) of dCK. We found that dCK could decrease IR-induced total cell death and apoptosis. Moreover, dCK increased IR-induced autophagy and dCK-S74 is required for it. Western blotting showed that the ratio of phospho-Akt/Akt, phospho-mTOR/mTOR, phospho-P70S6K/P70S6K significantly decreased in dCK-WT and dCK-S74E cells than that in dCK-S74A cells following IR treatment. Reciprocal experiment by co-immunoprecipitation showed that mTOR can interact with wild-type dCK. IR increased polyploidy and decreased G2/M arrest in dCK knock-down cells as compared with control cells. Taken together, phosphorylated and activated dCK can inhibit IR-induced cell death including apoptosis and mitotic catastrophe, and promote IR-induced autophagy through PI3K/Akt/mTOR pathway.
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103
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Xue Z, Li Y, Zhang L, Shi W, Zhang C, Feng M, Zhang F, Tang D, Yu H, Gu M, Cheng Z. OsMTOPVIB Promotes Meiotic DNA Double-Strand Break Formation in Rice. MOLECULAR PLANT 2016; 9:1535-1538. [PMID: 27456761 DOI: 10.1016/j.molp.2016.07.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 06/13/2016] [Accepted: 07/15/2016] [Indexed: 05/25/2023]
Affiliation(s)
- Zhihui Xue
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Yafei Li
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Lei Zhang
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Wenqing Shi
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Chao Zhang
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Mengshi Feng
- Key Laboratory of Crop Genetics and Physiology of Jiangsu Province/Key Laboratory of Plant Functional Genomics of Ministry of Education, Yangzhou University, Yangzhou 225009, China
| | - Fanfan Zhang
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Ding Tang
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Hengxiu Yu
- Key Laboratory of Crop Genetics and Physiology of Jiangsu Province/Key Laboratory of Plant Functional Genomics of Ministry of Education, Yangzhou University, Yangzhou 225009, China
| | - Minghong Gu
- Key Laboratory of Crop Genetics and Physiology of Jiangsu Province/Key Laboratory of Plant Functional Genomics of Ministry of Education, Yangzhou University, Yangzhou 225009, China
| | - Zhukuan Cheng
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
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104
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Individual and Combined Expression of DNA Damage Response Molecules PARP1, γH2AX, BRCA1, and BRCA2 Predict Shorter Survival of Soft Tissue Sarcoma Patients. PLoS One 2016; 11:e0163193. [PMID: 27643881 PMCID: PMC5028069 DOI: 10.1371/journal.pone.0163193] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Accepted: 09/06/2016] [Indexed: 01/11/2023] Open
Abstract
DNA damage response (DDR) molecules are protective against genotoxic stresses. DDR molecules are also involved in the survival of cancer cells in patients undergoing anti-cancer therapies. Therefore, DDR molecules are potential markers of cancer progression in addition to being potential therapeutic targets. In this study, we evaluated the immunohistochemical expression of PARP1, γH2AX, BRCA1, and BRCA2 and their prognostic significance in 112 cases of soft tissue sarcoma (STS). The expression of PARP1, γH2AX, BRCA1, and BRCA2 were significantly associated with each other and were associated with higher tumor stage and presence of distant metastasis. The expression of PARP1, γH2AX, and BRCA2 were significantly associated with shorter disease-specific survival (DSS) and event-free survival (EFS) by univariate analysis. BRCA1 expression was associated with shorter DSS. Multivariate analysis revealed the expression of PARP1 and γH2AX to be independent indicators of poor prognosis of DSS and EFS. BRCA2 expression was an independent indicator of poor prognosis of DSS. In addition, the combined expressional patterns of PARP1, γH2AX, BRCA1, and BRCA2 (CSddrm) were independent prognostic predictors of DSS (P < 0.001) and EFS (P = 0.016). The ten-year DSS rate of the CSddrm-low, CSddrm-intermediate, and CSddrm-high subgroups were 81%, 26%, and 0%, respectively. In conclusion, this study demonstrates that the individual and combined expression patterns of the DDR molecules PARP1, γH2AX, BRCA1, and BRCA2 could be predictive of the prognosis of STS patients and suggests that controlling the activity of these DDR molecules could be employed in new therapeutic stratagems for the treatment of STS.
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105
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Skrdlant L, Stark JM, Lin RJ. Myelodysplasia-associated mutations in serine/arginine-rich splicing factor SRSF2 lead to alternative splicing of CDC25C. BMC Mol Biol 2016; 17:18. [PMID: 27552991 PMCID: PMC4994158 DOI: 10.1186/s12867-016-0071-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2016] [Accepted: 08/16/2016] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND Serine-arginine rich splicing factor 2 (SRSF2) is a protein known for its role in RNA splicing and genome stability. It has been recently discovered that SRSF2, along with other splicing regulators, is frequently mutated in patients with myelodysplastic syndrome (MDS). The most common MDS mutations in SRSF2 occur at proline 95; the mutant proteins are shown to have different RNA binding preferences, which may contribute to splicing changes detected in mutant cells. However, the influence of these SRSF2 MDS-associated mutations on specific splicing events remains poorly understood. RESULTS A tetracycline-inducible TF-1 erythroleukemia cell line was transduced with retroviruses to create cell lines expressing HA-tagged wildtype SRSF2, SRSF2 with proline 95 point mutations found in MDS, or SRSF2 with a deletion of one of the four major domains of the protein. Effects of these mutants on apoptosis and specific alternative splicing events were evaluated. Cells were also treated with DNA damaging drugs for comparison. MDS-related P95 point mutants of SRSF2 were expressed and phosphorylated at similar levels as wildtype SRSF2. However, cells expressing mutant SRSF2 exhibited higher levels of apoptosis than cells expressing wildtype SRSF2. Regarding alternative splicing events, in nearly all examined cases, SRSF2 P95 mutants acted in a similar fashion as the wildtype SRSF2. However, cells expressing SRSF2 P95 mutants had a percent increase in the C5 spliced isoform of cell division cycle 25C (CDC25C). The same alternative splicing of CDC25C was detected by treating cells with DNA damaging drugs, such as cisplatin, camptothecin, and trichostatin A at appropriate dosage. However, unlike DNA damaging drugs, SRSF2 P95 mutants did not activate the Ataxia telangiectasia mutated (ATM) pathway. CONCLUSION SRSF2 P95 mutants lead to alternative splicing of CDC25C in a manner that is not dependent on the DNA damage response.
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Affiliation(s)
- Lindsey Skrdlant
- Department of Molecular and Cellular Biology, Irell & Manella Graduate School of Biological Sciences, Beckman Research Institute of the City of Hope, Duarte, CA 91010 USA
| | - Jeremy M. Stark
- Department of Cancer Genetics and Epigenetics, Irell & Manella Graduate School of Biological Sciences, Beckman Research Institute of the City of Hope, Duarte, CA 91010 USA
| | - Ren-Jang Lin
- Department of Molecular and Cellular Biology, Irell & Manella Graduate School of Biological Sciences, Beckman Research Institute of the City of Hope, Duarte, CA 91010 USA
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106
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Wang P, Zhang H, Hou H, Wang Q, Li Y, Huang Y, Xie L, Gao F, He S, Li L. Cell cycle arrest induced by inhibitors of epigenetic modifications in maize (Zea mays) seedling leaves: characterization of the process and possible mechanisms involved. THE NEW PHYTOLOGIST 2016; 211:646-657. [PMID: 27040740 DOI: 10.1111/nph.13942] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 02/20/2016] [Indexed: 06/05/2023]
Abstract
Epigenetic modifications play crucial roles in the regulation of chromatin architecture and are involved in cell cycle progression, including mitosis and meiosis. To explore the relationship between epigenetic modifications and the cell cycle, we treated maize (Zea mays) seedlings with six different epigenetic modification-related inhibitors and identified the postsynthetic phase (G2 ) arrest via flow cytometry analysis. Total H4K5ac levels were significantly increased and the distribution of H3S10ph signalling was obviously changed in mitosis under various treatments. Further statistics of the cells in different periods of mitosis confirmed that the cell cycle was arrested at preprophase. Concentrations of hydrogen peroxide were relatively higher in the treated plants and the antioxidant thiourea could negate the influence of the inhibitors. Moreover, all of the treated plants displayed negative results in the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labelling (TUNEL) and γ-H2AX immunostaining assays after exposure for 3 d. Additionally, the expression level of topoisomerase genes in the treated plants was relatively lower than that in the untreated plants. These results suggest that these inhibitors of epigenetic modifications could cause preprophase arrest via reactive oxygen species formation inhibiting the expression of DNA topoisomerase genes, accompanied by changes in the H4K5ac and H3S10ph histone modifications.
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Affiliation(s)
- Pu Wang
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Hao Zhang
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Haoli Hou
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Qing Wang
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Yingnan Li
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Yan Huang
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Liangfu Xie
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Fei Gao
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Shibin He
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Lijia Li
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, 430072, China
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107
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Xin Q, Shen Y, Li X, Lu W, Wang X, Han X, Dong F, Wan L, Yang G, Hong D, Cheng Z. MS5 Mediates Early Meiotic Progression and Its Natural Variants May Have Applications for Hybrid Production in Brassica napus. THE PLANT CELL 2016; 28:1263-78. [PMID: 27194707 PMCID: PMC4944402 DOI: 10.1105/tpc.15.01018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 05/16/2016] [Indexed: 05/02/2023]
Abstract
During meiotic prophase I, chromatin undergoes dynamic changes to establish a structural basis for essential meiotic events. However, the mechanism that coordinates chromosome structure and meiotic progression remains poorly understood in plants. Here, we characterized a spontaneous sterile mutant MS5(b)MS5(b) in oilseed rape (Brassica napus) and found its meiotic chromosomes were arrested at leptotene. MS5 is preferentially expressed in reproductive organs and encodes a Brassica-specific protein carrying conserved coiled-coil and DUF626 domains with unknown function. MS5 is essential for pairing of homologs in meiosis, but not necessary for the initiation of DNA double-strand breaks. The distribution of the axis element-associated protein ASY1 occurs independently of MS5, but localization of the meiotic cohesion subunit SYN1 requires functional MS5. Furthermore, both the central element of the synaptonemal complex and the recombination element do not properly form in MS5(b)MS5(b) mutants. Our results demonstrate that MS5 participates in progression of meiosis during early prophase I and its allelic variants lead to differences in fertility, which may provide a promising strategy for pollination control for heterosis breeding.
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Affiliation(s)
- Qiang Xin
- National Key Laboratory of Crop Genetic Improvement, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Yi Shen
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Xi Li
- National Key Laboratory of Crop Genetic Improvement, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Wei Lu
- National Key Laboratory of Crop Genetic Improvement, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, China College of Life Science, South-central University for Nationalities, Wuhan 430074, China
| | - Xiang Wang
- National Key Laboratory of Crop Genetic Improvement, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Xue Han
- National Key Laboratory of Crop Genetic Improvement, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Faming Dong
- National Key Laboratory of Crop Genetic Improvement, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Lili Wan
- National Key Laboratory of Crop Genetic Improvement, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Guangsheng Yang
- National Key Laboratory of Crop Genetic Improvement, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Dengfeng Hong
- National Key Laboratory of Crop Genetic Improvement, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Zhukuan Cheng
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
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108
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Johansson P, Fasth A, Ek T, Hammarsten O. Validation of a flow cytometry-based detection of γ-H2AX, to measure DNA damage for clinical applications. CYTOMETRY PART B-CLINICAL CYTOMETRY 2016; 92:534-540. [PMID: 27060560 DOI: 10.1002/cyto.b.21374] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Revised: 03/16/2016] [Accepted: 04/01/2016] [Indexed: 12/18/2022]
Abstract
BACKGROUND The nucleosomal histone protein H2AX is specifically phosphorylated (γ-H2AX) adjacent to DNA double-strand breaks (DSBs) and is used for quantifying DSBs. Many chemotherapies and ionizing radiation (IR) used in cancer treatment result in DSBs. Therefore, γ-H2AX has a significant potential as a biomarker in evaluating patient sensitivity and responsiveness to IR and chemotherapy. METHODS Here, we report a flow cytometry-based quantification of γ-H2AX (FCM-γ-H2AX assay) customized for clinical practice. RESULTS We validated that our method is able to detect DNA damage in peripheral blood mononuclear cells (PBMCs) treated with DSB inducing agents. The method also detected the DNA repair deficiency in PBMCs treated with DNA repair inhibitors, as well as the deficiency in DNA repair signaling in PBMCs from two ataxia telangiectasia patients. CONCLUSIONS The FCM-γ-H2AX assay has sufficient analytical sensitivity and precision to measure levels of DNA damage and DNA repair for clinical purposes. © 2016 International Clinical Cytometry Society.
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Affiliation(s)
- Pegah Johansson
- Department of Clinical Chemistry and Transfusion Medicine, Institute of Biomedicine, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Anders Fasth
- Department of Pediatrics, Institute of Clinical Sciences, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Torben Ek
- Department of Pediatrics, Hospital of Halland, Halmstad, Sweden
| | - Ola Hammarsten
- Department of Clinical Chemistry and Transfusion Medicine, Institute of Biomedicine, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
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109
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Wang H, Hu Q, Tang D, Liu X, Du G, Shen Y, Li Y, Cheng Z. OsDMC1 Is Not Required for Homologous Pairing in Rice Meiosis. PLANT PHYSIOLOGY 2016; 171:230-41. [PMID: 26960731 PMCID: PMC4854709 DOI: 10.1104/pp.16.00167] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Accepted: 03/07/2016] [Indexed: 05/13/2023]
Abstract
Meiotic homologous recombination is pivotal to sexual reproduction. DMC1, a conserved recombinase, is involved in directing single-end invasion between interhomologs during meiotic recombination. In this study, we identified OsDMC1A and OsDMC1B, two closely related proteins in rice (Oryza sativa) with high sequence similarity to DMC1 proteins from other species. Analysis of Osdmc1a and Osdmc1b Tos17 insertion mutants indicated that these genes are functionally redundant. Immunolocalization analysis revealed OsDMC1 foci occurred at leptotene, which disappeared from late pachytene chromosomes in wild-type meiocytes. According to cytological analyses, homologous pairing is accomplished in the Osdmc1a Osdmc1b double mutant, but synapsis is seriously disrupted. The reduced number of bivalents and abnormal OsHEI10 foci in Osdmc1a Osdmc1b establishes an essential role for OsDMC1 in crossover formation. In the absence of OsDMC1, early recombination events probably occur normally, leading to normal localization of γH2AX, PAIR3, OsMRE11, OsCOM1, and OsRAD51C. Moreover, OsDMC1 was not detected in pairing-defective mutants, such as pair2, pair3, Oscom1, and Osrad51c, while it was loaded onto meiotic chromosomes in zep1, Osmer3, Oszip4, and Oshei10 Taken together, these results suggest that during meiosis, OsDMC1 is dispensable for homologous pairing in rice, which is quite different from the DMC1 homologs identified so far in other organisms.
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Affiliation(s)
- Hongjun Wang
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Qing Hu
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Ding Tang
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Xiaofei Liu
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Guijie Du
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Yi Shen
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Yafei Li
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Zhukuan Cheng
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
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110
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Abstract
Because the genome stores all genetic information required for growth and development, it is of pivotal importance to maintain DNA integrity, especially during cell division, when the genome is prone to replication errors and damage. Although over the last two decades it has become evident that the basic cell cycle toolbox of plants shares several similarities with those of fungi and mammals, plants appear to have evolved a set of distinct checkpoint regulators in response to different types of DNA stress. This might be a consequence of plants' sessile lifestyle, which exposes them to a set of unique DNA damage-inducing conditions. In this review, we highlight the types of DNA stress that plants typically experience and describe the plant-specific molecular mechanisms that control cell division in response to these stresses.
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Affiliation(s)
- Zhubing Hu
- Department of Plant Systems Biology, VIB, B-9052 Gent, Belgium
| | - Toon Cools
- Department of Plant Systems Biology, VIB, B-9052 Gent, Belgium
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111
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Liu YS, Cheng RY, Lo YL, Hsu C, Chen SH, Chiu CC, Wang LF. Distinct CPT-induced deaths in lung cancer cells caused by clathrin-mediated internalization of CP micelles. NANOSCALE 2016; 8:3510-3522. [PMID: 26796318 DOI: 10.1039/c5nr08345a] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We previously synthesized a chondroitin sulfate-graft-poly(ε-caprolactone) copolymer (H-CP) with a high content of poly(ε-caprolactone) (18.7 mol%), which self-assembled in water into a rod-like micelle to encapsulate hydrophobic camptothecin (CPT) in the core (micelle/CPT) for tumor-targeted drug delivery. As a result of the recognition of the micelle by CD44, the micelle/CPT entered CRL-5802 cells efficiently and released CPT efficaciously, resulting in higher tumor suppression than commercial CPT-11. In this study, H1299 cells were found to have a higher CD44 expression than CRL-5802 cells. However, the lower CD44-expressing CRL-5802 cells had a higher percentage of cell death and higher cellular uptake of the micelle/CPT than the higher CD44-expressing H1299 cells. Examination of the internalization pathway of the micelle/CPT in the presence of different endocytic chemical inhibitors showed that the CRL-5802 cells involved clathrin-mediated endocytosis, which was not found in the H1299 cells. Analysis of the cell cycle of the two cell lines exposed to the micelle/CPT revealed that the CRL-5802 cells arrested mainly in the S phase and the H1299 cells arrested mainly in the G2-M phase. A consistent result was also found in the evaluation of γ-H2AX expression, which was about three-fold higher in the CRL-5802 cells than in the H1299 cells. A near-infrared dye, IR780, was encapsulated into the micelle to observe the in vivo biodistribution of the micelle/IR780 in tumor-bearing mice. The CRL-5802 tumor showed a higher fluorescence intensity than the H1299 tumor at any tracing time after 1 h. Thus we tentatively concluded that CRL-5802 cells utilized the clathrin-mediated internalization pathway and arrested in the S phase on exposure to the micelle/CPT; all are possible reasons for the better therapeutic outcome in CRL-5802 cells than in H1299 cells.
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Affiliation(s)
- Yu-Sheng Liu
- School of Pharmacy, Kaohsiung Medical University, Kaohsiung 807, Taiwan
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112
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H2AX deficiency is associated with erythroid dysplasia and compromised haematopoietic stem cell function. Sci Rep 2016; 6:19589. [PMID: 26791933 PMCID: PMC4726203 DOI: 10.1038/srep19589] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Accepted: 11/10/2015] [Indexed: 12/22/2022] Open
Abstract
Myelodysplastic syndromes (MDS) are clonal disorders of haematopoiesis characterised by dysplastic changes of major myeloid cell lines. However, the mechanisms underlying these dysplastic changes are poorly understood. Here, we used a genetically modified mouse model and human patient data to examine the physiological roles of H2AX in haematopoiesis and how the loss of H2AX contributes to dyserythropoiesis in MDS. H2AX knockout mice showed cell-autonomous anaemia and erythroid dysplasia, mimicking dyserythropoiesis in MDS. Also, dyserythropoiesis was increased in MDS patients with the deletion of chromosome 11q23, where H2AX is located. Although loss of H2AX did not affect the early stage of terminal erythropoiesis, enucleation was decreased. H2AX deficiency also led to the loss of quiescence of hematopoietic stem and progenitor cells, which dramatically compromised their bone marrow engraftment. These results reveal important roles of H2AX in late-stage terminal erythropoiesis and hematopoietic stem cell function.
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113
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Krüger K, Ziegler V, Hartmann C, Henninger C, Thomale J, Schupp N, Fritz G. Lovastatin prevents cisplatin-induced activation of pro-apoptotic DNA damage response (DDR) of renal tubular epithelial cells. Toxicol Appl Pharmacol 2015; 292:103-14. [PMID: 26739623 DOI: 10.1016/j.taap.2015.12.023] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Revised: 12/22/2015] [Accepted: 12/27/2015] [Indexed: 12/20/2022]
Abstract
The platinating agent cisplatin (CisPt) is commonly used in the therapy of various types of solid tumors. The anticancer efficacy of CisPt largely depends on the formation of bivalent DNA intrastrand crosslinks, which stimulate mechanisms of the DNA damage response (DDR), thereby triggering checkpoint activation, gene expression and cell death. The clinically most relevant adverse effect associated with CisPt treatment is nephrotoxicity that results from damage to renal tubular epithelial cells. Here, we addressed the question whether the HMG-CoA-reductase inhibitor lovastatin affects the DDR of renal cells by employing rat renal proximal tubular epithelial (NRK-52E) cells as in vitro model. The data show that lovastatin has extensive inhibitory effects on CisPt-stimulated DDR of NRK-52E cells as reflected on the levels of phosphorylated ATM, Chk1, Chk2, p53 and Kap1. Mitigation of CisPt-induced DDR by lovastatin was independent of the formation of DNA damage as demonstrated by (i) the analysis of Pt-(GpG) intrastrand crosslink formation by Southwestern blot analyses and (ii) the generation of DNA strand breaks as analyzed on the level of nuclear γH2AX foci and employing the alkaline comet assay. Lovastatin protected NRK-52E cells from the cytotoxicity of high CisPt doses as shown by measuring cell viability, cellular impedance and flow cytometry-based analyses of cell death. Importantly, the statin also reduced the level of kidney DNA damage and apoptosis triggered by CisPt treatment of mice. The data show that the lipid-lowering drug lovastatin extensively counteracts pro-apoptotic signal mechanisms of the DDR of tubular epithelial cells following CisPt injury.
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Affiliation(s)
- Katharina Krüger
- Institute of Toxicology, Medical Faculty, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Verena Ziegler
- Institute of Toxicology, Medical Faculty, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Christina Hartmann
- Institute of Toxicology, Medical Faculty, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Christian Henninger
- Institute of Toxicology, Medical Faculty, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Jürgen Thomale
- Institute of Cell Biology, University Duisburg-Essen, 45122 Essen, Germany
| | - Nicole Schupp
- Institute of Toxicology, Medical Faculty, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Gerhard Fritz
- Institute of Toxicology, Medical Faculty, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany.
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114
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Colmegna B, Uboldi S, Frapolli R, Licandro SA, Panini N, Galmarini CM, Badri N, Spanswick VJ, Bingham JP, Kiakos K, Erba E, Hartley JA, D'Incalci M. Increased sensitivity to platinum drugs of cancer cells with acquired resistance to trabectedin. Br J Cancer 2015; 113:1687-93. [PMID: 26633559 PMCID: PMC4701998 DOI: 10.1038/bjc.2015.407] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Revised: 10/29/2015] [Accepted: 11/06/2015] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND In order to investigate the mechanisms of acquired resistance to trabectedin, trabectedin-resistant human myxoid liposarcoma (402-91/T) and ovarian carcinoma (A2780/T) cell lines were derived and characterised in vitro and in vivo. METHODS Resistant cell lines were obtained by repeated exposures to trabectedin. Characterisation was performed by evaluating drug sensitivity, cell cycle perturbations, DNA damage and DNA repair protein expression. In vivo experiments were performed on A2780 and A2780/T xenografts. RESULTS 402-91/T and A2780/T cells were six-fold resistant to trabectedin compared with parental cells. Resistant cells were found to be hypersensitive to UV light and did not express specific proteins involved in the nucleotide excision repair (NER) pathway: XPF and ERCC1 in 402-91/T and XPG in A2780/T. NER deficiency in trabectedin-resistant cells was associated with the absence of a G2/M arrest induced by trabectedin and with enhanced sensitivity (two-fold) to platinum drugs. In A2780/T, this collateral sensitivity, confirmed in vivo, was associated with an increased formation of DNA interstrand crosslinks. CONCLUSIONS Our finding that resistance to trabectedin is associated with the loss of NER function, with a consequent increased sensitivity to platinum drugs, provides the rational for sequential use of these drugs in patients who have acquired resistance to trabectedin.
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Affiliation(s)
- B Colmegna
- Department of Oncology, IRCCS – Istituto di Ricerche Farmacologiche Mario Negri, via La Masa 19, Milan 20156, Italy
| | - S Uboldi
- Department of Oncology, IRCCS – Istituto di Ricerche Farmacologiche Mario Negri, via La Masa 19, Milan 20156, Italy
| | - R Frapolli
- Department of Oncology, IRCCS – Istituto di Ricerche Farmacologiche Mario Negri, via La Masa 19, Milan 20156, Italy
| | - S A Licandro
- Department of Oncology, IRCCS – Istituto di Ricerche Farmacologiche Mario Negri, via La Masa 19, Milan 20156, Italy
| | - N Panini
- Department of Oncology, IRCCS – Istituto di Ricerche Farmacologiche Mario Negri, via La Masa 19, Milan 20156, Italy
| | - C M Galmarini
- Department of Research and Development (R&D), PharmaMar S.A., Colmenar Viejo, Madrid 28770, Spain
| | - Nadia Badri
- Department of Research and Development (R&D), PharmaMar S.A., Colmenar Viejo, Madrid 28770, Spain
| | - V J Spanswick
- Cancer Research UK Drug-DNA Interactions Research Group, UCL Cancer Institute, Paul O'Gorman Building, 72 Huntley Street, London WC1E 6BT, UK
| | - J P Bingham
- Cancer Research UK Drug-DNA Interactions Research Group, UCL Cancer Institute, Paul O'Gorman Building, 72 Huntley Street, London WC1E 6BT, UK
| | - Konstantinos Kiakos
- Cancer Research UK Drug-DNA Interactions Research Group, UCL Cancer Institute, Paul O'Gorman Building, 72 Huntley Street, London WC1E 6BT, UK
| | - E Erba
- Department of Oncology, IRCCS – Istituto di Ricerche Farmacologiche Mario Negri, via La Masa 19, Milan 20156, Italy
| | - J A Hartley
- Cancer Research UK Drug-DNA Interactions Research Group, UCL Cancer Institute, Paul O'Gorman Building, 72 Huntley Street, London WC1E 6BT, UK
| | - M D'Incalci
- Department of Oncology, IRCCS – Istituto di Ricerche Farmacologiche Mario Negri, via La Masa 19, Milan 20156, Italy
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115
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Wang T, Han P, He Y, Zhao C, Wang G, Yang W, Shan M, Zhu Y, Yang C, Weng M, Wu D, Gao L, Jin X, Wei Y, Cui B, Shen G, Li X. Lin28A enhances chemosensitivity of colon cancer cells to 5-FU by promoting apoptosis in a let-7 independent manner. Tumour Biol 2015; 37:7657-65. [PMID: 26687759 DOI: 10.1007/s13277-015-4559-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 12/01/2015] [Indexed: 02/04/2023] Open
Abstract
RNA-binding protein Lin28A is frequently over-expressed in human malignant tumors and is associated with tumor advance and poor prognosis. However, the expression pattern and functions of Lin28A in colon cancer are unknown. In this study, we detected the expression of Lin28A in colon cancer patients and tested the effect of Lin28A on the chemotherapeutic sensitivity of colon cancer cells to 5-fluorouracil (5-FU). As expected, we showed that Lin28A is up-regulated in 73.3 % of colon cancer patients. However, to our surprise, we found that oncogenic protein Lin28A-enforced expression in colon cancer cells enhanced the chemosensitivity of cancer cells to 5-FU via promoting the cell apoptosis. Further mechanisms study revealed that the effect of Lin28A increasing chemosensitivity of cancer cells is in a let-7 independent manner, but which is associated with decreasing the expression of DNA damage repair protein H2AX. Conclusively, here we reported an unexpected function of Lin28A, which may shed lights on fully understanding the physiological and pathological roles of this oncogene.
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Affiliation(s)
- Tianzhen Wang
- Department of Pathology, Harbin Medical University, Harbin, China
| | - Peng Han
- Department of Colorectal Surgery, The Affiliated Tumor Hospital of Harbin Medical University, Harbin, China
| | - Yan He
- Department of Pathology, Harbin Medical University, Harbin, China
| | - Ci Zhao
- Department of Gastrointestinal Medical Oncology, The Affiliated Tumor Hospital of Harbin Medical University, Harbin, China
| | - Guangyu Wang
- Department of Gastrointestinal Medical Oncology, The Affiliated Tumor Hospital of Harbin Medical University, Harbin, China
| | - Weiwei Yang
- Department of Pathology, Harbin Medical University, Harbin, China
| | - Ming Shan
- Department of Breast Surgery, The Affiliated Tumor Hospital of Harbin Medical University, Harbin, China
| | - Yuanyuan Zhu
- Department of Gastrointestinal Medical Oncology, The Affiliated Tumor Hospital of Harbin Medical University, Harbin, China
| | - Chao Yang
- Department of Pathology, Harbin Medical University, Harbin, China
| | - Mingjiao Weng
- Department of Pathology, Harbin Medical University, Harbin, China
| | - Di Wu
- Department of Obstetrics and Gynecology, First Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Lin Gao
- Center for Endemic Disease Control, Chinese Center for Disease Control and Prevention, Harbin Medical University, Harbin, China
| | - Xiaoming Jin
- Department of Pathology, Harbin Medical University, Harbin, China
| | - Yunwei Wei
- Department of General Surgery, The First Affiliated Hospital of Harbin Medical University, Harbin, China
| | - BinBin Cui
- Department of Colorectal Surgery, The Affiliated Tumor Hospital of Harbin Medical University, Harbin, China.
| | - Guomin Shen
- Department of Medical Genetics, Medical College, Henan University of Science and Technology, Luoyang, China.
| | - Xiaobo Li
- Department of Pathology, Harbin Medical University, Harbin, China.
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116
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Schroeter A, Groh IAM, Del Favero G, Pignitter M, Schueller K, Somoza V, Marko D. Inhibition of topoisomerase II by phase II metabolites of resveratrol in human colon cancer cells. Mol Nutr Food Res 2015; 59:2448-59. [DOI: 10.1002/mnfr.201500352] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Revised: 09/15/2015] [Accepted: 09/18/2015] [Indexed: 12/21/2022]
Affiliation(s)
- Anika Schroeter
- Department of Food Chemistry and Toxicology; Faculty of Chemistry; University of Vienna; Vienna Austria
| | - Isabel Anna Maria Groh
- Department of Food Chemistry and Toxicology; Faculty of Chemistry; University of Vienna; Vienna Austria
| | - Giorgia Del Favero
- Department of Food Chemistry and Toxicology; Faculty of Chemistry; University of Vienna; Vienna Austria
| | - Marc Pignitter
- Department of Nutritional and Physiological Chemistry; Faculty of Chemistry; University of Vienna; Vienna Austria
| | - Katharina Schueller
- Department of Nutritional and Physiological Chemistry; Faculty of Chemistry; University of Vienna; Vienna Austria
| | - Veronika Somoza
- Department of Nutritional and Physiological Chemistry; Faculty of Chemistry; University of Vienna; Vienna Austria
| | - Doris Marko
- Department of Food Chemistry and Toxicology; Faculty of Chemistry; University of Vienna; Vienna Austria
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117
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Borrego-Soto G, Ortiz-López R, Rojas-Martínez A. Ionizing radiation-induced DNA injury and damage detection in patients with breast cancer. Genet Mol Biol 2015; 38:420-32. [PMID: 26692152 PMCID: PMC4763322 DOI: 10.1590/s1415-475738420150019] [Citation(s) in RCA: 145] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 07/15/2015] [Indexed: 12/26/2022] Open
Abstract
Breast cancer is the most common malignancy in women. Radiotherapy is frequently used in patients with breast cancer, but some patients may be more susceptible to ionizing radiation, and increased exposure to radiation sources may be associated to radiation adverse events. This susceptibility may be related to deficiencies in DNA repair mechanisms that are activated after cell-radiation, which causes DNA damage, particularly DNA double strand breaks. Some of these genetic susceptibilities in DNA-repair mechanisms are implicated in the etiology of hereditary breast/ovarian cancer (pathologic mutations in the BRCA 1 and 2 genes), but other less penetrant variants in genes involved in sporadic breast cancer have been described. These same genetic susceptibilities may be involved in negative radiotherapeutic outcomes. For these reasons, it is necessary to implement methods for detecting patients who are susceptible to radiotherapy-related adverse events. This review discusses mechanisms of DNA damage and repair, genes related to these functions, and the diagnosis methods designed and under research for detection of breast cancer patients with increased radiosensitivity.
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Affiliation(s)
- Gissela Borrego-Soto
- Departamento de Bioquímica y Medicina Molecular, Facultad de
Medicina, Universidad Autónoma de Nuevo León, Monterrey, Nuevo León, Mexico
- Centro de Investigación y Desarrollo en Ciencias de la Salud,
Universidad Autónoma de Nuevo León, Monterrey, Nuevo León, Mexico
| | - Rocío Ortiz-López
- Departamento de Bioquímica y Medicina Molecular, Facultad de
Medicina, Universidad Autónoma de Nuevo León, Monterrey, Nuevo León, Mexico
- Centro de Investigación y Desarrollo en Ciencias de la Salud,
Universidad Autónoma de Nuevo León, Monterrey, Nuevo León, Mexico
| | - Augusto Rojas-Martínez
- Departamento de Bioquímica y Medicina Molecular, Facultad de
Medicina, Universidad Autónoma de Nuevo León, Monterrey, Nuevo León, Mexico
- Centro de Investigación y Desarrollo en Ciencias de la Salud,
Universidad Autónoma de Nuevo León, Monterrey, Nuevo León, Mexico
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Yao K, Jiang X, He L, Tang Y, Yin G, Zeng Q, Jiang Z, Tan J. Anacardic acid sensitizes prostate cancer cells to radiation therapy by regulating H2AX expression. INTERNATIONAL JOURNAL OF CLINICAL AND EXPERIMENTAL PATHOLOGY 2015; 8:15926-15932. [PMID: 26884865 PMCID: PMC4730078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 11/22/2015] [Indexed: 06/05/2023]
Abstract
Anacardic acid (6-pentadecylsalicylic acid, AA), a natural compound isolated from the traditional medicine Amphipterygiumadstringens, has been reported as potential antitumor agents in various cancers including prostate cancer (PC). However, the effects and mechanism of AA on the radiosensitivity of prostate cancer remains unknown. The results indicated that AA exhibited strong antitumor activity in PC cell lines, either as a single agentor in combination with radiation. AA significantly induced the downregulation of H2AX and p-H2AX expression, increase of cell apoptosis and decreasing of cell invasion, which were reversed by overexpressed H2AX. These results suggest that AA sensitize prostate cancer cells to radiation therapy by repressing H2AX expression.
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Affiliation(s)
- Kun Yao
- Department of Urology, The Third Hospital of Central South University Changsha 410013, China
| | - Xianzhen Jiang
- Department of Urology, The Third Hospital of Central South University Changsha 410013, China
| | - Leye He
- Department of Urology, The Third Hospital of Central South University Changsha 410013, China
| | - Yuxin Tang
- Department of Urology, The Third Hospital of Central South University Changsha 410013, China
| | - Guangming Yin
- Department of Urology, The Third Hospital of Central South University Changsha 410013, China
| | - Qing Zeng
- Department of Urology, The Third Hospital of Central South University Changsha 410013, China
| | - Zhiqiang Jiang
- Department of Urology, The Third Hospital of Central South University Changsha 410013, China
| | - Jing Tan
- Department of Urology, The Third Hospital of Central South University Changsha 410013, China
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119
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Groh IAM, Rudakovski O, Gründken M, Schroeter A, Marko D, Esselen M. Methyleugenol and oxidative metabolites induce DNA damage and interact with human topoisomerases. Arch Toxicol 2015; 90:2809-2823. [DOI: 10.1007/s00204-015-1625-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 10/22/2015] [Indexed: 11/25/2022]
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120
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Nachtergael A, Poivre M, Belayew A, Duez P. In vitro genotoxicity tests point to an unexpected and harmful effect of a Magnolia and Aristolochia association. JOURNAL OF ETHNOPHARMACOLOGY 2015; 174:178-186. [PMID: 26278811 DOI: 10.1016/j.jep.2015.07.045] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Revised: 07/09/2015] [Accepted: 07/29/2015] [Indexed: 06/04/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE in the 1990s, a Belgian cohort of more than 100 patients reported cases of Aristolochic Acid Nephropathy (AAN). This progressive renal and interstitial fibrosis, frequently associated with urothelial malignancies, was consecutive to the Chinese-herbs based slimming capsules intake where a plant Stephania tetrandra S. Moore was replaced by a highly genotoxic Aristolochia species. 70% of the Belgian patients evolved into end-stage renal disease, requiring dialysis or renal transplantation. Furthermore the prevalence of upper urinary tract carcinoma was found alarmingly high in these patients. The Aristolochia adulteration was blamed for the intoxication cases and, to the best of our knowledge, the prescription itself has not been further investigated. AIM OF THE STUDY This work proposes to evaluate the in vitro cytotoxicity and genotoxicity of Aristolochia and Magnolia traditional aqueous decoctions and their association. MATERIALS AND METHODS The cytotoxicity of extracts has been assessed by a MTT cell proliferation assay and the genotoxicity by measuring the presence of γ-H2AX, a phosphorylated histone associated with DNA damages. RESULTS Treating cells for 24h with a mixture 1:1 of Magnolia officinalis and Aristolochia baetica decoctions led to an increase in the production of γ-H2AX. CONCLUSIONS This genotoxic potentiation warrants further studies but may lead to an explanatory factor for the "Chinese herb nephropathy" cases.
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Affiliation(s)
- Amandine Nachtergael
- Laboratory of Therapeutic Chemistry and Pharmacognosy, Faculty of Medicine and Pharmacy, Research Institute for Health Sciences and Technology, University of Mons - UMONS, 20 Place du Paarc, 7000 Mons, Belgium
| | - Mélanie Poivre
- Laboratory of Therapeutic Chemistry and Pharmacognosy, Faculty of Medicine and Pharmacy, Research Institute for Health Sciences and Technology, University of Mons - UMONS, 20 Place du Paarc, 7000 Mons, Belgium
| | - Alexandra Belayew
- Laboratory of Molecular Biology, Faculty of Medicine and Pharmacy, Research Institute for Health Sciences and Technology, University of Mons - UMONS, 20 Place du Parc, 7000 Mons, Belgium
| | - Pierre Duez
- Laboratory of Therapeutic Chemistry and Pharmacognosy, Faculty of Medicine and Pharmacy, Research Institute for Health Sciences and Technology, University of Mons - UMONS, 20 Place du Paarc, 7000 Mons, Belgium.
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121
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Genome-wide redistribution of H3K27me3 is linked to genotoxic stress and defective growth. Proc Natl Acad Sci U S A 2015; 112:E6339-48. [PMID: 26578794 DOI: 10.1073/pnas.1511377112] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
H3K9 methylation directs heterochromatin formation by recruiting multiple heterochromatin protein 1 (HP1)-containing complexes that deacetylate histones and methylate cytosine bases in DNA. In Neurospora crassa, a single H3K9 methyltransferase complex, called the DIM-5,-7,-9, CUL4, DDB1 Complex (DCDC), is required for normal growth and development. DCDC-deficient mutants are hypersensitive to the genotoxic agent methyl methanesulfonate (MMS), but the molecular basis of genotoxic stress is unclear. We found that both the MMS sensitivity and growth phenotypes of DCDC-deficient strains are suppressed by mutation of embryonic ectoderm development or Su-(var)3-9; E(z); Trithorax (set)-7, encoding components of the H3K27 methyltransferase Polycomb repressive complex-2 (PRC2). Trimethylated histone H3K27 (H3K27me3) undergoes genome-wide redistribution to constitutive heterochromatin in DCDC- or HP1-deficient mutants, and introduction of an H3K27 missense mutation is sufficient to rescue phenotypes of DCDC-deficient strains. Accumulation of H3K27me3 in heterochromatin does not compensate for silencing; rather, strains deficient for both DCDC and PRC2 exhibit synthetic sensitivity to the topoisomerase I inhibitor Camptothecin and accumulate γH2A at heterochromatin. Together, these data suggest that PRC2 modulates the response to genotoxic stress.
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122
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Brooks L, Lyons SM, Mahoney JM, Welch JD, Liu Z, Marzluff WF, Whitfield ML. A multiprotein occupancy map of the mRNP on the 3' end of histone mRNAs. RNA (NEW YORK, N.Y.) 2015; 21:1943-65. [PMID: 26377992 PMCID: PMC4604434 DOI: 10.1261/rna.053389.115] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Accepted: 07/23/2015] [Indexed: 05/20/2023]
Abstract
The animal replication-dependent (RD) histone mRNAs are coordinately regulated with chromosome replication. The RD-histone mRNAs are the only known cellular mRNAs that are not polyadenylated. Instead, the mature transcripts end in a conserved stem-loop (SL) structure. This SL structure interacts with the stem-loop binding protein (SLBP), which is involved in all aspects of RD-histone mRNA metabolism. We used several genomic methods, including high-throughput sequencing of cross-linked immunoprecipitate (HITS-CLIP) to analyze the RNA-binding landscape of SLBP. SLBP was not bound to any RNAs other than histone mRNAs. We performed bioinformatic analyses of the HITS-CLIP data that included (i) clustering genes by sequencing read coverage using CVCA, (ii) mapping the bound RNA fragment termini, and (iii) mapping cross-linking induced mutation sites (CIMS) using CLIP-PyL software. These analyses allowed us to identify specific sites of molecular contact between SLBP and its RD-histone mRNA ligands. We performed in vitro crosslinking assays to refine the CIMS mapping and found that uracils one and three in the loop of the histone mRNA SL preferentially crosslink to SLBP, whereas uracil two in the loop preferentially crosslinks to a separate component, likely the 3'hExo. We also performed a secondary analysis of an iCLIP data set to map UPF1 occupancy across the RD-histone mRNAs and found that UPF1 is bound adjacent to the SLBP-binding site. Multiple proteins likely bind the 3' end of RD-histone mRNAs together with SLBP.
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Affiliation(s)
- Lionel Brooks
- Department of Genetics, Dartmouth Geisel School of Medicine, Hanover, New Hampshire 03755, USA
| | - Shawn M Lyons
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - J Matthew Mahoney
- Department of Genetics, Dartmouth Geisel School of Medicine, Hanover, New Hampshire 03755, USA
| | - Joshua D Welch
- Department of Computer Science, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Zhongle Liu
- Department of Genetics, Dartmouth Geisel School of Medicine, Hanover, New Hampshire 03755, USA
| | - William F Marzluff
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Michael L Whitfield
- Department of Genetics, Dartmouth Geisel School of Medicine, Hanover, New Hampshire 03755, USA
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123
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Park SH, Noh SJ, Kim KM, Bae JS, Kwon KS, Jung SH, Kim JR, Lee H, Chung MJ, Moon WS, Kang MJ, Jang KY. Expression of DNA Damage Response Molecules PARP1, γH2AX, BRCA1, and BRCA2 Predicts Poor Survival of Breast Carcinoma Patients. Transl Oncol 2015; 8:239-49. [PMID: 26310369 PMCID: PMC4562981 DOI: 10.1016/j.tranon.2015.04.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Revised: 04/18/2015] [Accepted: 04/24/2015] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND: Poly(ADP-ribose) polymerase 1 (PARP1), γH2AX, BRCA1, and BRCA2 are conventional molecular indicators of DNA damage in cells and are often overexpressed in various cancers. In this study, we aimed, using immunohistochemical detection, whether the co-expression of PARP1, γH2AX, BRCA1, and BRCA2 in breast carcinoma (BCA) tissue can provide more reliable prediction of survival of BCA patients. MATERIALS AND METHODS: We investigated immunohistochemical expression and prognostic significance of the expression of PARP1, γH2AX, BRCA1, and BRCA2 in 192 cases of BCAs. RESULTS: The expression of these four molecules predicted earlier distant metastatic relapse, shorter overall survival (OS), and relapse-free survival (RFS) by univariate analysis. Multivariate analysis revealed the expression of PARP1, γH2AX, and BRCA2 as independent poor prognostic indicators of OS and RFS. In addition, the combined expressional pattern of BRCA1, BRCA2, PARP1, and γH2AX (CSbbph) was an additional independent prognostic predictor for OS (P < .001) and RFS (P < .001). The 10-year OS rate was 95% in the CSbbph-low (CSbbph scores 0 and 1) subgroup, but that was only 35% in the CSbbph-high (CSbbph score 4) subgroup. CONCLUSION: This study has demonstrated that the individual and combined expression patterns of PARP1, γH2AX, BRCA1, and BRCA2 could be helpful in determining an accurate prognosis for BCA patients and for the selection of BCA patients who could potentially benefit from anti-PARP1 therapy with a combination of genotoxic chemotherapeutic agents.
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Affiliation(s)
- See-Hyoung Park
- Division of Gynecologic Oncology, Department of Obstetrics and Gynecology, Stanford University School of Medicine, Stanford, CA, USA
| | - Sang Jae Noh
- Department of Pathology, Chonbuk National University Medical School, Research Institute of Clinical Medicine of Chonbuk National University, Biomedical Research Institute of Chonbuk National University Hospital and Research Institute for Endocrine Sciences, Jeonju, Republic of Korea
| | - Kyoung Min Kim
- Department of Pathology, Chonbuk National University Medical School, Research Institute of Clinical Medicine of Chonbuk National University, Biomedical Research Institute of Chonbuk National University Hospital and Research Institute for Endocrine Sciences, Jeonju, Republic of Korea
| | - Jun Sang Bae
- Department of Pathology, Chonbuk National University Medical School, Research Institute of Clinical Medicine of Chonbuk National University, Biomedical Research Institute of Chonbuk National University Hospital and Research Institute for Endocrine Sciences, Jeonju, Republic of Korea
| | - Keun Sang Kwon
- Department of Preventive Medicine, Chonbuk National University Medical School, Research Institute of Clinical Medicine of Chonbuk National University, Biomedical Research Institute of Chonbuk National University Hospital and Research Institute for Endocrine Sciences, Jeonju, Republic of Korea
| | - Sung Hoo Jung
- Department of Surgery, Chonbuk National University Medical School, Research Institute of Clinical Medicine of Chonbuk National University, Biomedical Research Institute of Chonbuk National University Hospital and Research Institute for Endocrine Sciences, Jeonju, Republic of Korea
| | - Jung Ryul Kim
- Department of Orthopaedic Surgery, Chonbuk National University Medical School, Research Institute of Clinical Medicine of Chonbuk National University, Biomedical Research Institute of Chonbuk National University Hospital and Research Institute for Endocrine Sciences, Jeonju, Republic of Korea
| | - Ho Lee
- Department of Forensic Medicine, Chonbuk National University Medical School, Research Institute of Clinical Medicine of Chonbuk National University, Biomedical Research Institute of Chonbuk National University Hospital and Research Institute for Endocrine Sciences, Jeonju, Republic of Korea
| | - Myoung Ja Chung
- Department of Pathology, Chonbuk National University Medical School, Research Institute of Clinical Medicine of Chonbuk National University, Biomedical Research Institute of Chonbuk National University Hospital and Research Institute for Endocrine Sciences, Jeonju, Republic of Korea
| | - Woo Sung Moon
- Department of Pathology, Chonbuk National University Medical School, Research Institute of Clinical Medicine of Chonbuk National University, Biomedical Research Institute of Chonbuk National University Hospital and Research Institute for Endocrine Sciences, Jeonju, Republic of Korea
| | - Myoung Jae Kang
- Department of Pathology, Chonbuk National University Medical School, Research Institute of Clinical Medicine of Chonbuk National University, Biomedical Research Institute of Chonbuk National University Hospital and Research Institute for Endocrine Sciences, Jeonju, Republic of Korea
| | - Kyu Yun Jang
- Department of Pathology, Chonbuk National University Medical School, Research Institute of Clinical Medicine of Chonbuk National University, Biomedical Research Institute of Chonbuk National University Hospital and Research Institute for Endocrine Sciences, Jeonju, Republic of Korea.
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124
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Johnston ML, Young EF, Shepard KL. Whole-blood immunoassay for γH2AX as a radiation biodosimetry assay with minimal sample preparation. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2015; 54:365-372. [PMID: 25935208 DOI: 10.1007/s00411-015-0595-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 04/16/2015] [Indexed: 06/04/2023]
Abstract
The current state of the art in high-throughput minimally invasive radiation biodosimetry involves the collection of samples in the field and analysis at a centralized facility. We have developed a simple biological immunoassay for radiation exposure that could extend this analysis out of the laboratory into the field. Such a forward placed assay would facilitate triage of a potentially exposed population. The phosphorylation and localization of the histone H2AX at double-stranded DNA breaks has already been proven to be an adequate surrogate assay for reporting DNA damage proportional to radiation dose. Here, we develop an assay for phosphorylated H2AX directed against minimally processed sample lysates. We conduct preliminary verification of H2AX phosphorylation using irradiated mouse embryo fibroblast cultures. Additional dosimetry is performed using human blood samples irradiated ex vivo. The assay reports H2AX phosphorylation in human blood samples in response to ionizing radiation over a range of 0-5 Gy in a linear fashion, without requiring filtering, enrichment, or purification of the blood sample.
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Affiliation(s)
- Matthew L Johnston
- Bialanx, Inc., 511 Avenue of the Americas, Suite 267, New York, NY, USA,
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125
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PKR inhibits the DNA damage response, and is associated with poor survival in AML and accelerated leukemia in NHD13 mice. Blood 2015. [PMID: 26202421 DOI: 10.1182/blood-2015-03-635227] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Increased expression of the interferon-inducible double-stranded RNA-activated protein kinase (PKR) has been reported in acute leukemia and solid tumors, but the role of PKR has been unclear. Now, our results indicate that high PKR expression in CD34(+) cells of acute myeloid leukemia (AML) patients correlates with worse survival and shortened remission duration. Significantly, we find that PKR has a novel and previously unrecognized nuclear function to inhibit DNA damage response signaling and double-strand break repair. Nuclear PKR antagonizes ataxia-telangiectasia mutated (ATM) activation by a mechanism dependent on protein phosphatase 2A activity. Thus, inhibition of PKR expression or activity promotes ATM activation, γ-H2AX formation, and phosphorylation of NBS1 following ionizing irradiation. PKR transgenic but not PKR null mice demonstrate a mutator phenotype characterized by radiation-induced and age-associated genomic instability that was partially reversed by short-term pharmacologic PKR inhibition. Furthermore, the age-associated accumulation of somatic mutations that occurs in the Nup98-HOXD13 (NHD13) mouse model of leukemia progression was significantly elevated by co-expression of a PKR transgene, whereas knockout of PKR expression or pharmacologic inhibition of PKR activity reduced the frequency of spontaneous mutations in vivo. Thus, PKR cooperated with the NHD13 transgene to accelerate leukemia progression and shorten survival. Taken together, these results indicate that increased nuclear PKR has an oncogenic function that promotes the accumulation of potentially deleterious mutations. Thus, PKR inhibition may be a therapeutically useful strategy to prevent leukemia progression or relapse, and improve clinical outcomes.
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126
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Wang T, Wang G, Hao D, Liu X, Wang D, Ning N, Li X. Aberrant regulation of the LIN28A/LIN28B and let-7 loop in human malignant tumors and its effects on the hallmarks of cancer. Mol Cancer 2015; 14:125. [PMID: 26123544 PMCID: PMC4512107 DOI: 10.1186/s12943-015-0402-5] [Citation(s) in RCA: 126] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2015] [Accepted: 06/24/2015] [Indexed: 12/13/2022] Open
Abstract
RNA binding proteins (RBPs) and microRNAs (miRNAs) are two of the most important post-transcriptional regulators of gene expression, and their aberrant expression contributes to the development of human malignancies. Let-7, one of the most well-known tumor suppressors, is frequently down-regulated in a variety of human cancers. The RBP LIN28A/LIN28B, a direct target of the let-7 family of miRNAs, is an inhibitor of let-7 biogenesis and is frequently up-regulated in cancers. Aberrant regulation of the LIN28A/LIN28B and let-7 loop in human malignant tumors is reportedly involved in cancer development, contributing to cellular proliferation, cell death resistance, angiogenesis, metastasis, metabolism reprogramming, tumor-associated inflammation, genome instability, acquiring immortality and evading immune destruction. In this review, we summarized the mechanisms of LIN28A/LIN28B and let-7 loop aberrant regulation in human cancer and discussed the roles and potential mechanisms of the LIN28A/LIN28B and let-7 loop in regulating the hallmarks of cancer. The crosstalk between LIN28A/LIN28B and let-7 loop and certain oncogenes (such as MYC, RAS, PI3K/AKT, NF-κB and β-catenin) in regulating hallmarks of cancer has also been discussed.
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Affiliation(s)
- Tianzhen Wang
- Department of Pathology, Harbin Medical University, Harbin, China.
| | - Guangyu Wang
- Department of Gastrointestinal Medical Oncology, The Affiliated Tumor Hospital of Harbin Medical University, Harbin, China.
| | - Dapeng Hao
- Faculty of Health Sciences, University of Macau, Taipa, Macau, China.
| | - Xi Liu
- Center of Cardiovascular, Inner Mongolia People's Hospital, Hohhot, Inner Mongolia, China.
| | - Dong Wang
- College of Bioinformatics Science and Technology, Harbin Medical University, Harbin, China.
| | - Ning Ning
- Department of Gastrointestinal Surgery, International Hospital of Pecking University, Beijing, China.
| | - Xiaobo Li
- Department of Pathology, Harbin Medical University, Harbin, China.
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127
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Salzano M, Sanz-García M, Monsalve DM, Moura DS, Lazo PA. VRK1 chromatin kinase phosphorylates H2AX and is required for foci formation induced by DNA damage. Epigenetics 2015; 10:373-83. [PMID: 25923214 PMCID: PMC4623420 DOI: 10.1080/15592294.2015.1028708] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
All types of DNA damage cause a local alteration and relaxation of chromatin structure. Sensing and reacting to this initial chromatin alteration is a necessary trigger for any type of DNA damage response (DDR). In this context, chromatin kinases are likely candidates to participate in detection and reaction to a locally altered chromatin as a consequence of DNA damage and, thus, initiate the appropriate cellular response. In this work, we demonstrate that VRK1 is a nucleosomal chromatin kinase and that its depletion causes loss of histones H3 and H4 acetylation, which are required for chromatin relaxation, both in basal conditions and after DNA damage, independently of ATM. Moreover, VRK1 directly and stably interacts with histones H2AX and H3 in basal conditions. In response to DNA damage induced by ionizing radiation, histone H2AX is phosphorylated in Ser139 by VRK1. The phosphorylation of H2AX and the formation of γH2AX foci induced by ionizing radiation (IR), are prevented by VRK1 depletion and are rescued by kinase-active, but not kinase-dead, VRK1. In conclusion, we found that VRK1 is a novel chromatin component that reacts to its alterations and participates very early in DDR, functioning by itself or in cooperation with ATM.
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Affiliation(s)
- Marcella Salzano
- a Experimental Therapeutics and Translational Oncology Program; Instituto de Biología Molecular y Celular del Cáncer; Consejo Superior de Investigaciones Científicas (CSIC)-Universidad de Salamanca; Campus Miguel de Unamuno ; Salamanca , Spain
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128
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Leifert WR, Siddiqui SM. γH2AX is a biomarker of modulated cytostatic drug resistance. Cytometry A 2015; 87:692-5. [PMID: 25902732 DOI: 10.1002/cyto.a.22672] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2015] [Accepted: 03/06/2015] [Indexed: 12/11/2022]
Affiliation(s)
- Wayne R Leifert
- CSIRO Food and Nutrition Flagship, Genome Health and Healthy Ageing, Adelaide, South Australia, 5000, Australia
| | - Sabbir Mohammad Siddiqui
- CSIRO Food and Nutrition Flagship, Genome Health and Healthy Ageing, Adelaide, South Australia, 5000, Australia.,School of Agriculture, Food and Wine, University of Adelaide, Urrbrae, South Australia, 5064, Australia
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129
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Reddig A, Lorenz S, Hiemann R, Guttek K, Hartig R, Heiserich L, Eberle C, Peters V, Schierack P, Sack U, Roggenbuck D, Reinhold D. Assessment of modulated cytostatic drug resistance by automated γH2AX analysis. Cytometry A 2015; 87:724-32. [DOI: 10.1002/cyto.a.22667] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Revised: 03/05/2015] [Accepted: 03/12/2015] [Indexed: 12/25/2022]
Affiliation(s)
- Annika Reddig
- Institute of Molecular and Clinical Immunology, Otto-von-Guericke-University Magdeburg; Magdeburg Germany
| | | | - Rico Hiemann
- Faculty of Natural Sciences; Brandenburg University of Technology Cottbus-Senftenberg; Senftenberg Germany
| | - Karina Guttek
- Institute of Molecular and Clinical Immunology, Otto-von-Guericke-University Magdeburg; Magdeburg Germany
| | - Roland Hartig
- Institute of Molecular and Clinical Immunology, Otto-von-Guericke-University Magdeburg; Magdeburg Germany
| | | | | | | | - Peter Schierack
- Faculty of Natural Sciences; Brandenburg University of Technology Cottbus-Senftenberg; Senftenberg Germany
| | - Ulrich Sack
- Institute of Clinical Immunology, Medical Faculty, University of Leipzig; Leipzig Germany
| | - Dirk Roggenbuck
- Medipan GmbH; Dahlewitz/Berlin Germany
- Faculty of Natural Sciences; Brandenburg University of Technology Cottbus-Senftenberg; Senftenberg Germany
| | - Dirk Reinhold
- Institute of Molecular and Clinical Immunology, Otto-von-Guericke-University Magdeburg; Magdeburg Germany
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130
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Vriet C, Hennig L, Laloi C. Stress-induced chromatin changes in plants: of memories, metabolites and crop improvement. Cell Mol Life Sci 2015; 72:1261-73. [PMID: 25578097 PMCID: PMC11113909 DOI: 10.1007/s00018-014-1792-z] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2014] [Revised: 11/19/2014] [Accepted: 11/20/2014] [Indexed: 01/18/2023]
Abstract
Exposure of plants to adverse environmental conditions leads to extensive transcriptional changes. Genome-wide approaches and gene function studies have revealed the importance of chromatin-level control in the regulation of stress-responsive gene expression. Advances in understanding chromatin modifications implicated in plant stress response and identifying proteins involved in chromatin-mediated transcriptional responses to stress are briefly presented in this review. We then highlight how chromatin-mediated gene expression changes can be coupled to the metabolic status of the cell, since many of the chromatin-modifying proteins involved in transcriptional regulation depend on cofactors and metabolites that are shared with enzymes in basic metabolism. Lastly, we discuss the stability and heritability of stress-induced chromatin changes and the potential of chromatin-based strategies for increasing stress tolerance of crops.
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Affiliation(s)
- Cécile Vriet
- BVME UMR 7265, Lab Genet Biophys Plantes, Aix Marseille Université, Marseille, 13284, France,
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131
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Yang H, Luo J, Liu Z, Zhou R, Luo H. MicroRNA-138 Regulates DNA Damage Response in Small Cell Lung Cancer Cells by Directly Targeting H2AX. Cancer Invest 2015; 33:126-36. [DOI: 10.3109/07357907.2015.1006329] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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132
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Chemical “Diversity” of Chromatin Through Histone Variants and Histone Modifications. ACTA ACUST UNITED AC 2015. [DOI: 10.1007/s40610-015-0005-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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133
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Distinct increased outliers among 136 rectal cancer patients assessed by γH2AX. Radiat Oncol 2015; 10:36. [PMID: 25889915 PMCID: PMC4330982 DOI: 10.1186/s13014-015-0344-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Accepted: 02/01/2015] [Indexed: 11/10/2022] Open
Abstract
Background In recent years attention has focused on γH2AX as a very sensitive double strand break indicator. It has been suggested that γH2AX might be able to predict individual radiosensitivity. Our aim was to study the induction and repair of DNA double strand breaks labelled by γH2AX in a large cohort. Methods In a prospective study lymphocytes of 136 rectal cancer (RC) patients and 59 healthy individuals were ex vivo irradiated (IR) and initial DNA damage was compared to remaining DNA damage after 2 Gy and 24 hours repair time and preexisting DNA damage in unirradiated lymphocytes. Lymphocytes were immunostained with anti-γH2AX antibodies and microscopic images with an extended depth of field were acquired. γH2AX foci counting was performed using a semi-automatic image analysis software. Results Distinct increased values of preexisting and remaining γH2AX foci in the group of RC patients were found compared to the healthy individuals. Additionally there are clear differences within the groups and there are outliers in about 12% of the RC patients after ex vivo IR. Conclusions The γH2AX assay has the capability to identify a group of outliers which are most probably patients with increased radiosensitivity having the highest risk of suffering radiotherapy-related late sequelae.
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134
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Kinders R, Ferry-Galow K, Wang L, Srivastava AK, Ji JJ, Parchment RE. Implementation of validated pharmacodynamic assays in multiple laboratories: challenges, successes, and limitations. Clin Cancer Res 2015; 20:2578-86. [PMID: 24831280 DOI: 10.1158/1078-0432.ccr-14-0476] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
There is a "life cycle" of pharmacodynamic (PD) biomarker assays that guides the development and clinical implementation in our laboratories. The well-recognized elements of analytical assay validation and demonstration of fitness-for-purpose of the biomarker, specimen collection, handling, and assay methods are only a part of the required activities. Assay transfer across laboratories and testing on actual human clinical specimens are vital for understanding assay performance and robustness. In our experience, this patient specimen-centered approach has required assay method modifications, some unexpected, but which were critical to successful implementation in clinical trials. In addition, dispersing assays throughout the National Cancer Institute's clinical trials network has required the development of calibrator and control materials as well as formal training courses for smooth implementation. One measure of success of this approach has been that a number of the assays developed at NCI's Frederick National Laboratory have ultimately reached the stage of commercialization, enabling wide accessibility of the PD biomarker assays by the research community. See all articles in this ccr focus section, "Progress in pharmacodynamic endpoints."
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Affiliation(s)
- Robert Kinders
- Authors' Affiliations: Laboratory of Human Toxicology and Pharmacology; National Cancer Target Validation Laboratory, Applied/Developmental Research Directorate, Frederick National Laboratory for Cancer Research and Leidos Biomedical Research, Inc., Frederick, Maryland
| | - Kate Ferry-Galow
- Authors' Affiliations: Laboratory of Human Toxicology and Pharmacology; National Cancer Target Validation Laboratory, Applied/Developmental Research Directorate, Frederick National Laboratory for Cancer Research and Leidos Biomedical Research, Inc., Frederick, Maryland
| | - Lihua Wang
- Authors' Affiliations: Laboratory of Human Toxicology and Pharmacology; National Cancer Target Validation Laboratory, Applied/Developmental Research Directorate, Frederick National Laboratory for Cancer Research and Leidos Biomedical Research, Inc., Frederick, Maryland
| | - Apurva K Srivastava
- Authors' Affiliations: Laboratory of Human Toxicology and Pharmacology; National Cancer Target Validation Laboratory, Applied/Developmental Research Directorate, Frederick National Laboratory for Cancer Research and Leidos Biomedical Research, Inc., Frederick, Maryland
| | - Jiuping Jay Ji
- Authors' Affiliations: Laboratory of Human Toxicology and Pharmacology; National Cancer Target Validation Laboratory, Applied/Developmental Research Directorate, Frederick National Laboratory for Cancer Research and Leidos Biomedical Research, Inc., Frederick, Maryland
| | - Ralph E Parchment
- Authors' Affiliations: Laboratory of Human Toxicology and Pharmacology; National Cancer Target Validation Laboratory, Applied/Developmental Research Directorate, Frederick National Laboratory for Cancer Research and Leidos Biomedical Research, Inc., Frederick, Maryland
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135
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H2AX phosphorylation regulated by p38 is involved in Bim expression and apoptosis in chronic myelogenous leukemia cells induced by imatinib. Apoptosis 2015; 19:1281-92. [PMID: 24830786 DOI: 10.1007/s10495-014-0997-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Increasing evidence suggests that histone H2AX plays a critical role in regulation of tumor cell apoptosis and acts as a novel human tumor suppressor protein. However, the action of H2AX in chronic myelogenous leukemia (CML) cells is unknown. The detailed mechanism and epigenetic regulation by H2AX remain elusive in cancer cells. Here, we report that H2AX was involved in apoptosis of CML cells. Overexpression of H2AX increased apoptotic sensitivity of CML cells (K562) induced by imatinib. However, overexpression of Ser139-mutated H2AX (blocking phosphorylation) decreased sensitivity of K562 cells to apoptosis. Similarly, knockdown of H2AX made K562 cells resistant to apoptotic induction. These results revealed that the function of H2AX involved in apoptosis is strictly related to its phosphorylation (Ser139). Our data further indicated that imatinib may stimulate mitogen-activated protein kinase (MAPK) family member p38, and H2AX phosphorylation followed a similar time course, suggesting a parallel response. H2AX phosphorylation can be blocked by p38 siRNA or its inhibitor. These data demonstrated that H2AX phosphorylation was regulated by p38 MAPK pathway in K562 cells. However, the p38 MAPK downstream, mitogen- and stress-activated protein kinase-1 and -2, which phosphorylated histone H3, were not required for H2AX phosphorylation during apoptosis. Finally, we provided epigenetic evidence that H2AX phosphorylation regulated apoptosis-related gene Bim expression. Blocking of H2AX phosphorylation inhibited Bim gene expression. Taken together, these data demonstrated that H2AX phosphorylation regulated by p38 is involved in Bim expression and apoptosis in CML cells induced by imatinib.
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136
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Wu Z, Ji J, Tang D, Wang H, Shen Y, Shi W, Li Y, Tan X, Cheng Z, Luo Q. OsSDS is essential for DSB formation in rice meiosis. FRONTIERS IN PLANT SCIENCE 2015; 6:21. [PMID: 25691887 PMCID: PMC4315026 DOI: 10.3389/fpls.2015.00021] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Accepted: 01/10/2015] [Indexed: 05/18/2023]
Abstract
SDS is a meiosis specific cyclin-like protein and required for DMC1 mediated double-strand break (DSB) repairing in Arabidopsis. Here, we found its rice homolog, OsSDS, is essential for meiotic DSB formation. The Ossds mutant is normal in vegetative growth but both male and female gametes are inviable. The Ossds meiocytes exhibit severe defects in homologous pairing and synapsis. No γH2AX immunosignals in Ossds meiocytes together with the suppression of chromosome fragmentation in Ossds-1 Osrad51c, both provide strong evidences that OsSDS is essential for meiotic DSB formation. Immunostaining investigations revealed that meiotic chromosome axes are normally formed but both SC installation and localization of recombination elements are failed in Ossds. We suspected that this cyclin protein has been differentiated pretty much between monocots and dicots on its function in meiosis.
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Affiliation(s)
- Zhigang Wu
- Ministry of Education Key Laboratory of Agriculture Biodiversity for Plant Disease Management, Yunnan Agricultural UniversityKunming, China
| | - Jianhui Ji
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of SciencesBeijing, China
- School of Life Sciences, Huaiyin Normal UniversityHuaian, China
| | - Ding Tang
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of SciencesBeijing, China
| | - Hongjun Wang
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of SciencesBeijing, China
| | - Yi Shen
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of SciencesBeijing, China
| | - Wenqing Shi
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of SciencesBeijing, China
| | - Yafei Li
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of SciencesBeijing, China
| | - Xuelin Tan
- Ministry of Education Key Laboratory of Agriculture Biodiversity for Plant Disease Management, Yunnan Agricultural UniversityKunming, China
| | - Zhukuan Cheng
- State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of SciencesBeijing, China
- *Correspondence: Zhukuan Cheng, State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, No.1 West Beichen Road, Chaoyang District, Beijing 100101, China e-mail:
| | - Qiong Luo
- Ministry of Education Key Laboratory of Agriculture Biodiversity for Plant Disease Management, Yunnan Agricultural UniversityKunming, China
- Qiong Luo, Ministry of Education Key Laboratory of Agriculture Biodiversity for Plant Disease Management, Yunnan Agricultural University, Heilongtan, Guandu District, Kunming 650201, China e-mail:
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137
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Sone K, Piao L, Nakakido M, Ueda K, Jenuwein T, Nakamura Y, Hamamoto R. Critical role of lysine 134 methylation on histone H2AX for γ-H2AX production and DNA repair. Nat Commun 2014; 5:5691. [PMID: 25487737 PMCID: PMC4268694 DOI: 10.1038/ncomms6691] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Accepted: 10/29/2014] [Indexed: 12/19/2022] Open
Abstract
The presence of phosphorylated histone H2AX (γ-H2AX) is associated with the local activation of DNA-damage repair pathways. Although γ-H2AX deregulation in cancer has previously been reported, the molecular mechanism involved and its relationship with other histone modifications remain largely unknown. Here we find that the histone methyltransferase SUV39H2 methylates histone H2AX on lysine 134. When H2AX was mutated to abolish K134 methylation, the level of γ-H2AX became significantly reduced. We also found lower γ-H2AX activity following the introduction of double-strand breaks in Suv39h2 knockout cells or on SUV39H2 knockdown. Tissue microarray analyses of clinical lung and bladder tissues also revealed a positive correlation between H2AX K134 methylation and γ-H2AX levels. Furthermore, introduction of K134-substituted histone H2AX enhanced radio- and chemosensitivity of cancer cells. Overall, our results suggest that H2AX methylation plays a role in the regulation of γ-H2AX abundance in cancer. γ-H2AX The Ser139 phosphorylated form of H2AX, γ-H2AX, is generated in response to DNA double-strand breaks and is involved in the repair process. Here, Sone et al. show that H2AX K134 methylation by SUV39H2 is crucial for the production of γ-H2AX, and that loss of methylation correlates with radio- and chemosensitivity.
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Affiliation(s)
- Kenbun Sone
- Section of Hematology/Oncology, Department of Medicine, University of Chicago, 5841 South Maryland Avenue, MC2115, Chicago, Illinois 60637, USA
| | - Lianhua Piao
- Section of Hematology/Oncology, Department of Medicine, University of Chicago, 5841 South Maryland Avenue, MC2115, Chicago, Illinois 60637, USA
| | - Makoto Nakakido
- Section of Hematology/Oncology, Department of Medicine, University of Chicago, 5841 South Maryland Avenue, MC2115, Chicago, Illinois 60637, USA
| | - Koji Ueda
- Graduate School of Frontier Sciences, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan
| | - Thomas Jenuwein
- Max Planck Institute of Immunobiology and Epigenetics, Stübeweg 51, D-79108 Freiburg, Germany
| | - Yusuke Nakamura
- Section of Hematology/Oncology, Department of Medicine, University of Chicago, 5841 South Maryland Avenue, MC2115, Chicago, Illinois 60637, USA
| | - Ryuji Hamamoto
- 1] Section of Hematology/Oncology, Department of Medicine, University of Chicago, 5841 South Maryland Avenue, MC2115, Chicago, Illinois 60637, USA [2] Laboratory of Molecular Medicine, Human Genome Center, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan
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138
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Herbert AD, Carr AM, Hoffmann E. FindFoci: a focus detection algorithm with automated parameter training that closely matches human assignments, reduces human inconsistencies and increases speed of analysis. PLoS One 2014; 9:e114749. [PMID: 25478967 PMCID: PMC4257716 DOI: 10.1371/journal.pone.0114749] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Accepted: 11/13/2014] [Indexed: 11/19/2022] Open
Abstract
Accurate and reproducible quantification of the accumulation of proteins into foci in cells is essential for data interpretation and for biological inferences. To improve reproducibility, much emphasis has been placed on the preparation of samples, but less attention has been given to reporting and standardizing the quantification of foci. The current standard to quantitate foci in open-source software is to manually determine a range of parameters based on the outcome of one or a few representative images and then apply the parameter combination to the analysis of a larger dataset. Here, we demonstrate the power and utility of using machine learning to train a new algorithm (FindFoci) to determine optimal parameters. FindFoci closely matches human assignments and allows rapid automated exploration of parameter space. Thus, individuals can train the algorithm to mirror their own assignments and then automate focus counting using the same parameters across a large number of images. Using the training algorithm to match human assignments of foci, we demonstrate that applying an optimal parameter combination from a single image is not broadly applicable to analysis of other images scored by the same experimenter or by other experimenters. Our analysis thus reveals wide variation in human assignment of foci and their quantification. To overcome this, we developed training on multiple images, which reduces the inconsistency of using a single or a few images to set parameters for focus detection. FindFoci is provided as an open-source plugin for ImageJ.
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Affiliation(s)
- Alex D. Herbert
- MRC Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, BN1 9RQ, United Kingdom
- * E-mail:
| | - Antony M. Carr
- MRC Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, BN1 9RQ, United Kingdom
| | - Eva Hoffmann
- MRC Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, BN1 9RQ, United Kingdom
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139
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Kim J, Lee JS, Jung J, Lim I, Lee JY, Park MJ. Emodin suppresses maintenance of stemness by augmenting proteosomal degradation of epidermal growth factor receptor/epidermal growth factor receptor variant III in glioma stem cells. Stem Cells Dev 2014; 24:284-95. [PMID: 25229646 DOI: 10.1089/scd.2014.0210] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
There is a growing body of evidence that small subpopulations of cells with stem cell-like characteristics within most solid tumors are responsible for the malignancy of aggressive cancer cells and that targeting these cells might be a good therapeutic strategy to reduce the risk of tumor relapse after therapy. Here, we examined the effects of emodin (1,3,8-trihydroxy-6-methylanthraquinone), an active component of the root and rhizome of Rheum palmatum that has several biological activities, including antitumor effects, on primary cultured glioma stem cells (GSCs). Emodin inhibited the self-renewal activity of GSCs in vitro as evidenced by neurosphere formation, limiting dilution, and soft agar clonogenic assays. Emodin inhibited the maintenance of stemness by suppressing the expression of Notch intracellular domain, nonphosphorylated β-catenin, and phosphorylated STAT3 proteins. In addition, treatment with emodin partially induced apoptosis, reduced cell invasiveness, and sensitized GSCs to ionizing radiation. Intriguingly, emodin induced proteosomal degradation of epidermal growth factor receptor (EGFR)/EGFR variant III (EGFRvIII) by interfering with the association of EGFR/EGFRvIII with heat shock protein 90, resulting in the suppression of stemness pathways. Based on these data, we propose that emodin could be considered as a potent therapeutic adjuvant that targets GSCs.
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Affiliation(s)
- Jeongyub Kim
- 1 Divisions of Radiation Cancer Research, Research Center for Radio-Senescence , Korea Institute of Radiological and Medical Sciences, Seoul, Korea
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140
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Browning CL, The T, Mason MD, Wise JP. Titanium Dioxide Nanoparticles are not Cytotoxic or Clastogenic in Human Skin Cells. ACTA ACUST UNITED AC 2014; 4. [PMID: 26568896 PMCID: PMC4643289 DOI: 10.4172/2161-0525.1000239] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The application of nanoparticle technology is rapidly expanding. The reduced dimensionality of nanoparticles can give rise to changes in chemical and physical properties, often resulting in altered toxicity. People are exposed dermally to titanium dioxide (TiO2) nanoparticles in industrial and residential settings. The general public is increasingly exposed to these nanoparticles as their use in cosmetics, sunscreens and lotions expands. The toxicity of TiO2 nanoparticles towards human skin cells is unclear and understudied. We used a human skin fibroblast cell line to investigate the cytotoxicity and clastogenicity of TiO2 nanoparticles after 24 h exposure. In a clonogenic survival assay, treatments of 10, 50 and 100 μg/cm2 induced 97.8, 88.8 and 84.7% relative survival, respectively. Clastogenicity was assessed using a chromosomal aberration assay in order to determine whether TiO2 nanoparticles induced serious forms of DNA damage such as chromatid breaks, isochromatid lesions or chromatid exchanges. Treatments of 0, 10, 50 and 100 μg/cm2 induced 3.3, 3.0, 3.0 and 2.7% metaphases with damage, respectively. No isochromatid lesions or chromatid exchanges were detected. These data show that TiO2 nanoparticles are not cytotoxic or clastogenic to human skin cells.
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Affiliation(s)
- Cynthia L Browning
- Wise Laboratory of Environmental and Genetic Toxicology, University of Southern Maine, Portland ME 04103, USA ; Maine Center for Toxicology and Environmental Health, University of Southern Maine, Portland ME 04103, USA ; Graduate School of Biomedical Science and Engineering, University of Maine, Orono ME 04469, USA
| | - Therry The
- Wise Laboratory of Environmental and Genetic Toxicology, University of Southern Maine, Portland ME 04103, USA ; Maine Center for Toxicology and Environmental Health, University of Southern Maine, Portland ME 04103, USA
| | - Michael D Mason
- Graduate School of Biomedical Science and Engineering, University of Maine, Orono ME 04469, USA
| | - John Pierce Wise
- Wise Laboratory of Environmental and Genetic Toxicology, University of Southern Maine, Portland ME 04103, USA ; Maine Center for Toxicology and Environmental Health, University of Southern Maine, Portland ME 04103, USA ; Graduate School of Biomedical Science and Engineering, University of Maine, Orono ME 04469, USA
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Mo N, Lu YK, Xie WM, Liu Y, Zhou WX, Wang HX, Nong L, Jia YX, Tan AH, Chen Y, Li SS, Luo BH. Inhibition of autophagy enhances the radiosensitivity of nasopharyngeal carcinoma by reducing Rad51 expression. Oncol Rep 2014; 32:1905-12. [PMID: 25175062 DOI: 10.3892/or.2014.3427] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Accepted: 07/20/2014] [Indexed: 11/06/2022] Open
Abstract
Radiotherapy has long been considered as the mainstay of treatment for nasopharyngeal carcinoma (NPC). However, locoregional recurrence or distant metastasis may occur in some patients due to the radiation resistance of cancer cells. Autophagy plays a vital role in protecting cells against radiation. However, the mechanism of autophagy in radiation therapy remains obscure. In the present study, we demonstrated that suppression of autophagy related 5 (Atg5) aggravated ionizing radiation (IR)-induced DNA damage and apoptosis in human NPC cells without accelerating the cell cycle, whereas regulation of the cell cycle has been widely regarded as the most important determinant of IR sensitivity. Further study showed that inhibition of autophagy suppressed the mRNA expression of Rad51, a key protein of homologous recombination that has been demonstrated to play a critical role in the repair of DNA double-strand breaks induced by radiation. Moreover, suppression of Atg5 had no impact on the radiosensitivity when cells were pre-treated by the Rad51 inhibitor, and the enhanced radiosensitivity by Atg5 suppression was reversed by overexpression of Rad51 in human NPC cells. Our results suggest that inhibition of autophagy enhances the susceptibility of NPC cells to radiation by reducing Rad51 expression. Therefore, Rad51 targeted therapy may be investigated as a potential novel agent for the adjuvant treatment of traditional radiation of NPC.
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Affiliation(s)
- Ning Mo
- The Fifth Department of Chemotherapy, Affiliated Tumor Hospital of Guangxi Medical University, Nanning 530021, P.R. China
| | - Yong-Kui Lu
- The Fifth Department of Chemotherapy, Affiliated Tumor Hospital of Guangxi Medical University, Nanning 530021, P.R. China
| | - Wei-Min Xie
- The Fifth Department of Chemotherapy, Affiliated Tumor Hospital of Guangxi Medical University, Nanning 530021, P.R. China
| | - Yan Liu
- The Fifth Department of Chemotherapy, Affiliated Tumor Hospital of Guangxi Medical University, Nanning 530021, P.R. China
| | - Wen-Xian Zhou
- The Fifth Department of Chemotherapy, Affiliated Tumor Hospital of Guangxi Medical University, Nanning 530021, P.R. China
| | - Hong-Xue Wang
- The Fifth Department of Chemotherapy, Affiliated Tumor Hospital of Guangxi Medical University, Nanning 530021, P.R. China
| | - Li Nong
- The Fifth Department of Chemotherapy, Affiliated Tumor Hospital of Guangxi Medical University, Nanning 530021, P.R. China
| | - Yu-Xian Jia
- The Fifth Department of Chemotherapy, Affiliated Tumor Hospital of Guangxi Medical University, Nanning 530021, P.R. China
| | - Ai-Hua Tan
- The Fifth Department of Chemotherapy, Affiliated Tumor Hospital of Guangxi Medical University, Nanning 530021, P.R. China
| | - Ying Chen
- The Fifth Department of Chemotherapy, Affiliated Tumor Hospital of Guangxi Medical University, Nanning 530021, P.R. China
| | - Shan-Shan Li
- The Fifth Department of Chemotherapy, Affiliated Tumor Hospital of Guangxi Medical University, Nanning 530021, P.R. China
| | - Bao-Hua Luo
- The Fifth Department of Chemotherapy, Affiliated Tumor Hospital of Guangxi Medical University, Nanning 530021, P.R. China
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Holme JA, Nyvold HE, Tat V, Arlt VM, Bhargava A, Gutzkow KB, Solhaug A, Låg M, Becher R, Schwarze PE, Ask K, Ekeren L, Øvrevik J. Mechanisms linked to differences in the mutagenic potential of 1,3-dinitropyrene and 1,8-dinitropyrene. Toxicol Rep 2014; 1:459-473. [PMID: 28962260 PMCID: PMC4547165 DOI: 10.1016/j.toxrep.2014.07.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Revised: 07/07/2014] [Accepted: 07/08/2014] [Indexed: 11/22/2022] Open
Abstract
This study explores and characterizes the toxicity of two closely related carcinogenic dinitro-pyrenes (DNPs), 1,3-DNP and 1,8-DNP, in human bronchial epithelial BEAS-2B cells and mouse hepatoma Hepa1c1c7 cells. Neither 1,3-DNP nor 1,8-DNP (3–30 μM) induced cell death in BEAS-2B cells. In Hepa1c1c7 cells only 1,3-DNP (10–30 μM) induced a mixture of apoptotic and necrotic cell death after 24 h. Both compounds increased the level of reactive oxygen species (ROS) in BEAS-2B as measured by CM-H2DCFDA-fluorescence. A corresponding increase in oxidative damage to DNA was revealed by the formamidopyrimidine-DNA glycosylase (fpg)-modified comet assay. Without fpg, DNP-induced DNA damage detected by the comet assay was only found in Hepa1c1c7 cells. Only 1,8-DNP formed DNA adduct measured by 32P-postlabelling. In Hepa1c1c cells, 1,8-DNP induced phosphorylation of H2AX (γH2AX) and p53 at a lower concentration than 1,3-DNP and there was no direct correlation between DNA damage/DNA damage response (DR) and induced cytotoxicity. On the other hand, 1,3-DNP-induced apoptosis was inhibited by pifithrin-α, an inhibitor of p53 transcriptional activity. Furthermore, 1,3-DNP triggered an unfolded protein response (UPR), as measured by an increased expression of CHOP, ATF4 and XBP1. Thus, other types of damage possibly linked to endoplasmic reticulum (ER)-stress and/or UPR could be involved in the induced apoptosis. Our results suggest that the stronger carcinogenic potency of 1,8-DNP compared to 1,3-DNP is linked to its higher genotoxic effects. This in combination with its lower potency to induce cell death may increase the probability of causing mutations.
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Key Words
- 1,3-DNP, 1,3-dinitropyrene
- 1,3-Dinitropyrene
- 1,8-DNP, 1,8-dinitropyrene
- 1,8-Dinitropyrene
- 1-NP, 1-nitropyrene
- 3-NBA, 3-nitrobenzanthrone
- AhR, aromatic hydrocarbon receptor
- Apoptosis
- B[a]P, benzo[a]pyrene
- CM-H2DCFDA or H2DCFDA, 5-(and 6-)chloromethyl-2,7-dichlorodihydrofluorescein diacetate
- CYP, cytochrome P450
- Chk, checkpoint kinases
- DDR, DNA damage response
- DHE, dihydroethidium
- DMSO, dimethyl sulfoxide
- DNA damage
- ER, endoplasmic reticulum
- Hoechst 33258, 2(2-(4-hydroxyphenyl)-6-benzimidazole-6-(1-methyl-4-piperazyl)benzimidazole hydrochloride)
- Hoechst 33342, 2′-(4-ethoxyphenyl)-2′,5′-bis-1H-benzimidazole hydrochloride)
- NR, nitro-reductasesnitro-PAHnitro substituted-polycyclic aromatic hydrocarbon
- Nitro-PAHs
- PAH, polycyclic aromatic hydrocarbon
- PARP, poly(ADP-ribose) polymerase
- PFT, pifithrin
- PI, propidium iodide
- PM, particular matter
- RNS, reactive nitrogen species
- ROS, reactive oxygen species
- SSB, single strand breaks
- UPR, unfolded protein response
- fpg, formamidopyrimidine-DNA glycosylase
- zVAD-FMK, benzyolcarbonayl-Val-Ala-Asp-fluoromethyl ketone
- γH2AX, phosphorylated H2AX
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Affiliation(s)
- J A Holme
- Division of Environmental Medicine, Norwegian Institute of Public Health, N-0403 Oslo, Norway
| | - H E Nyvold
- Division of Environmental Medicine, Norwegian Institute of Public Health, N-0403 Oslo, Norway
| | - V Tat
- Department of Medicine, McMaster University, Hamilton, ON, Canada
| | - V M Arlt
- Analytical and Environmental Sciences Division, MRC-PHE Centre for Environment and Health, King's College London, London, United Kingdom
| | - A Bhargava
- Department of Medicine, McMaster University, Hamilton, ON, Canada
| | - K B Gutzkow
- Division of Environmental Medicine, Norwegian Institute of Public Health, N-0403 Oslo, Norway
| | - A Solhaug
- Norwegian Veterinary Institute, Oslo, Norway
| | - M Låg
- Division of Environmental Medicine, Norwegian Institute of Public Health, N-0403 Oslo, Norway
| | - R Becher
- Division of Environmental Medicine, Norwegian Institute of Public Health, N-0403 Oslo, Norway
| | - P E Schwarze
- Division of Environmental Medicine, Norwegian Institute of Public Health, N-0403 Oslo, Norway
| | - K Ask
- Department of Medicine, McMaster University, Hamilton, ON, Canada
| | - L Ekeren
- Division of Environmental Medicine, Norwegian Institute of Public Health, N-0403 Oslo, Norway
| | - J Øvrevik
- Division of Environmental Medicine, Norwegian Institute of Public Health, N-0403 Oslo, Norway
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143
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Systemic DNA damage accumulation under in vivo tumor growth can be inhibited by the antioxidant Tempol. Cancer Lett 2014; 353:248-57. [PMID: 25069035 DOI: 10.1016/j.canlet.2014.07.030] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 07/16/2014] [Accepted: 07/16/2014] [Indexed: 12/18/2022]
Abstract
Recently we found that mice bearing subcutaneous non-metastatic tumors exhibited elevated levels of two types of complex DNA damage, i.e., double-strand breaks and oxidatively-induced clustered DNA lesions in various tissues throughout the body, both adjacent to and distant from the tumor site. This DNA damage was dependent on CCL2, a cytokine involved in the recruitment and activation of macrophages, suggesting that this systemic DNA damage was mediated via tumor-induced chronic inflammatory responses involving cytokines, activation of macrophages, and consequent free radical production. If free radicals are involved, then a diet containing an antioxidant may decrease the distant DNA damage. Here we repeated our standard protocol in cohorts of two syngeneic tumor-bearing C57BL/6NCr mice that were on a Tempol-supplemented diet. We show that double-strand break and oxidatively-induced clustered DNA lesion levels were considerably decreased, about two- to three fold, in the majority of tissues studied from the tumor-bearing mice fed the antioxidant Tempol compared to the control tumor-bearing mice. Similar results were also observed in nude mice suggesting that the Tempol effects are independent of functioning adaptive immunity. This is the first in vivo study demonstrating the effect of a dietary antioxidant on abscopal DNA damage in tissues distant from a localized source of genotoxic stress. These findings may be important for understanding the mechanisms of genomic instability and carcinogenesis caused by chronic stress-induced systemic DNA damage and for developing preventative strategies.
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144
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Garcia-Canton C, Errington G, Anadon A, Meredith C. Characterisation of an aerosol exposure system to evaluate the genotoxicity of whole mainstream cigarette smoke using the in vitro γH2AX assay by high content screening. BMC Pharmacol Toxicol 2014; 15:41. [PMID: 25056295 PMCID: PMC4122049 DOI: 10.1186/2050-6511-15-41] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 07/16/2014] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND The genotoxic effect of cigarette smoke is routinely measured by treating cells with cigarette Particulate Matter (PM) at different dose levels in submerged cell cultures. However, PM exposure cannot be considered as a complete exposure as it does not contain the gas phase component of the cigarette smoke. The in vitro γH2AX assay by High Content Screening (HCS) has been suggested as a complementary tool to the standard battery of genotoxicity assays as it detects DNA double strand breaks in a high-throughput fashion. The aim of this study was to further optimise the in vitro γH2AX assay by HCS to enable aerosol exposure of human bronchial epithelial BEAS-2B cells at the air-liquid interface (ALI). METHODS Whole mainstream cigarette smoke (WMCS) from two reference cigarettes (3R4F and M4A) were assessed for their genotoxic potential. During the study, a further characterisation of the Borgwaldt RM20S® aerosol exposure system to include single dilution assessment with a reference gas was also carried out. RESULTS The results of the optimisation showed that both reference cigarettes produced a positive genotoxic response at all dilutions tested. However, the correlation between dose and response was low for both 3R4F and M4A (Pearson coefficient, r = -0.53 and -0.44 respectively). During the additional characterisation of the exposure system, it was observed that several pre-programmed dilutions did not perform as expected. CONCLUSIONS Overall, the in vitro γH2AX assay by HCS could be used to evaluate WMCS in cell cultures at the ALI. Additionally, the extended characterisation of the exposure system indicates that assessing the performance of the dilutions could improve the existing routine QC checks.
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Affiliation(s)
- Carolina Garcia-Canton
- British American Tobacco, Group Research and Development, Regents Park Road, Southampton, Hampshire SO15 8TL, UK
- Department of Toxicology and Pharmacology, Universidad Complutense de Madrid, Madrid, Spain
| | - Graham Errington
- British American Tobacco, Group Research and Development, Regents Park Road, Southampton, Hampshire SO15 8TL, UK
| | - Arturo Anadon
- Department of Toxicology and Pharmacology, Universidad Complutense de Madrid, Madrid, Spain
| | - Clive Meredith
- British American Tobacco, Group Research and Development, Regents Park Road, Southampton, Hampshire SO15 8TL, UK
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145
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Gerić M, Gajski G, Garaj-Vrhovac V. γ-H2AX as a biomarker for DNA double-strand breaks in ecotoxicology. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2014; 105:13-21. [PMID: 24780228 DOI: 10.1016/j.ecoenv.2014.03.035] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Revised: 03/27/2014] [Accepted: 03/29/2014] [Indexed: 06/03/2023]
Abstract
The visualisation of DNA damage response proteins enables the indirect measurement of DNA damage. Soon after the occurrence of a DNA double-strand break (DSB), the formation of γ-H2AX histone variants is to be expected. This review is focused on the potential use of the γ-H2AX foci assay in assessing the genotoxicity of environmental contaminants including cytostatic pharmaceuticals, since standard methods may not be sensitive enough to detect the damaging effect of low environmental concentrations of such drugs. These compounds are constantly released into the environment, potentially representing a threat to water quality, aquatic organisms, and, ultimately, human health. Our review of the literature revealed that this method could be used in the biomonitoring and risk assessment of aquatic systems affected by wastewater from the production, usage, and disposal of cytostatic pharmaceuticals.
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Affiliation(s)
- Marko Gerić
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, 10000 Zagreb, Croatia
| | - Goran Gajski
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, 10000 Zagreb, Croatia
| | - Vera Garaj-Vrhovac
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, 10000 Zagreb, Croatia.
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146
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Heterochromatin controls γH2A localization in Neurospora crassa. EUKARYOTIC CELL 2014; 13:990-1000. [PMID: 24879124 DOI: 10.1128/ec.00117-14] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In response to genotoxic stress, ATR and ATM kinases phosphorylate H2A in fungi and H2AX in animals on a C-terminal serine. The resulting modified histone, called γH2A, recruits chromatin-binding proteins that stabilize stalled replication forks or promote DNA double-strand-break repair. To identify genomic loci that might be prone to replication fork stalling or DNA breakage in Neurospora crassa, we performed chromatin immunoprecipitation (ChIP) of γH2A followed by next-generation sequencing (ChIP-seq). γH2A-containing nucleosomes are enriched in Neurospora heterochromatin domains. These domains are comprised of A·T-rich repetitive DNA sequences associated with histone H3 methylated at lysine-9 (H3K9me), the H3K9me-binding protein heterochromatin protein 1 (HP1), and DNA cytosine methylation. H3K9 methylation, catalyzed by DIM-5, is required for normal γH2A localization. In contrast, γH2A is not required for H3K9 methylation or DNA methylation. Normal γH2A localization also depends on HP1 and a histone deacetylase, HDA-1, but is independent of the DNA methyltransferase DIM-2. γH2A is globally induced in dim-5 mutants under normal growth conditions, suggesting that the DNA damage response is activated in these mutants in the absence of exogenous DNA damage. Together, these data suggest that heterochromatin formation is essential for normal DNA replication or repair.
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147
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Shapiro JA. Epigenetic control of mobile DNA as an interface between experience and genome change. Front Genet 2014; 5:87. [PMID: 24795749 PMCID: PMC4007016 DOI: 10.3389/fgene.2014.00087] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Accepted: 04/01/2014] [Indexed: 12/29/2022] Open
Abstract
Mobile DNA in the genome is subject to RNA-targeted epigenetic control. This control regulates the activity of transposons, retrotransposons and genomic proviruses. Many different life history experiences alter the activities of mobile DNA and the expression of genetic loci regulated by nearby insertions. The same experiences induce alterations in epigenetic formatting and lead to trans-generational modifications of genome expression and stability. These observations lead to the hypothesis that epigenetic formatting directed by non-coding RNA provides a molecular interface between life history events and genome alteration.
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Affiliation(s)
- James A. Shapiro
- Department of Biochemistry and Molecular Biology, University of ChicagoChicago, IL, USA
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148
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Gao R, Singh R, Kaul Z, Kaul SC, Wadhwa R. Targeting of DNA Damage Signaling Pathway Induced Senescence and Reduced Migration of Cancer cells. J Gerontol A Biol Sci Med Sci 2014; 70:701-13. [PMID: 24747666 DOI: 10.1093/gerona/glu019] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Accepted: 01/22/2014] [Indexed: 01/20/2023] Open
Abstract
The heat shock 70 family protein, mortalin, has pancytoplasmic distribution pattern in normal and perinuclear in cancer human cells. Cancer cells when induced to senesce by either chemicals or stress showed shift in mortalin staining pattern from perinuclear to pancytoplasmic type. Using such shift in mortalin staining as a reporter, we screened human shRNA library and identified nine senescence-inducing siRNA candidates. An independent Comparative Genomic Hybridization analysis of 35 breast cancer cell lines revealed that five (NBS1, BRCA1, TIN2, MRE11A, and KPNA2) of the nine genes located on chromosome regions identified as the gain of locus in more than 80% cell lines. By gene-specific PCR, these five genes were found to be frequently amplified in cancer cell lines. Bioinformatics revealed that the identified targets were connected to MRN (MRE11-RAD50-NBS1) complex, the DNA damage-sensing complex. We demonstrate that the identified shRNAs triggered DNA damage response and induced the expression of tumor suppressor protein p16(INK4A) causing growth arrest of cancer cells. Furthermore, cells showed decreased migration, mediated by decrease in matrix metalloproteases. Taken together, we demonstrate that the MRN complex is a potential target of cancer cell proliferation and migration, and staining pattern of mortalin could serve as an assay to identify senescence-inducing/anticancer reagents.
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Affiliation(s)
- Ran Gao
- Cell Proliferation Research Group and DBT-AIST International Laboratory for Advanced Biomedicine, National Institute of Advanced Industrial Science & Technology (AIST), Tsukuba, Ibaraki, Japan
| | - Rumani Singh
- Cell Proliferation Research Group and DBT-AIST International Laboratory for Advanced Biomedicine, National Institute of Advanced Industrial Science & Technology (AIST), Tsukuba, Ibaraki, Japan
| | - Zeenia Kaul
- Cell Proliferation Research Group and Department of Molecular Virology, Immunology and Medical Genetics, Wexner Cancer Center, College of Medicine, The Ohio State University, Columbus
| | - Sunil C Kaul
- Cell Proliferation Research Group and DBT-AIST International Laboratory for Advanced Biomedicine, National Institute of Advanced Industrial Science & Technology (AIST), Tsukuba, Ibaraki, Japan
| | - Renu Wadhwa
- Cell Proliferation Research Group and DBT-AIST International Laboratory for Advanced Biomedicine, National Institute of Advanced Industrial Science & Technology (AIST), Tsukuba, Ibaraki, Japan.
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149
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Leskovac A, Petrovic S, Guc-Scekic M, Vujic D, Joksic G. Radiation-induced mitotic catastrophe in FANCD2 primary fibroblasts. Int J Radiat Biol 2014; 90:373-81. [PMID: 24512567 DOI: 10.3109/09553002.2014.892224] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
PURPOSE As the Fanconi anemia (FA) pathway is required for appropriate cell cycle progression through mitosis and the completion of cell division, the aim of the present study was to determine the destiny of FA cells after irradiation in vitro and to elucidate any difference in radiosensitivity between FA and control cells. MATERIALS AND METHODS Analyses of phosphorylated histone H2AX (γ-H2AX) foci, micronuclei formation and cell cycle analysis were performed in unirradiated (0 min) and irradiated primary FA fibroblasts and in a control group at different post-irradiation times (30 min, 2 h, 5 h and 24 h). RESULTS The accumulation of γ-H2AX foci in irradiated FA fibroblasts was observed. At 24 h post-irradiation, 57% of FA cells were γ-H2AX foci-positive, significantly higher than in the control (p < 0.01). The cell cycle analysis has shown the transient G2/M arrest in irradiated FA fibroblasts. The portion of cells in the G2/M phase showed initial increase at 30 min post-irradiation and afterwards decreased over time reaching the pretreatment level 24 h after irradiation. Irradiated FA fibroblasts progressed to abnormal mitosis, as is shown by the production of cells with different nuclear morphologies from binucleated to multinucleated surrounded with micronuclei, and also by a high percentage of foci-positive micronuclei. The majority of radiation-induced micronuclei were γ-H2AX foci-positive, indicating that radiation-induced micronuclei contain fragments of damaged chromosomes. In contrast, in the control group, most of the micronuclei were classified as γ-H2AX foci-negative, which indicates that cells with unrepaired damage were blocked before entering mitosis. CONCLUSION The results clearly indicate that mitotic catastrophe might be an important cell-death mechanism involved in the response of FA fibroblasts to ionizing radiation.
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Affiliation(s)
- Andreja Leskovac
- Vinca Institute of Nuclear Sciences, University of Belgrade , Belgrade , Serbia
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150
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T-oligo as an anticancer agent in colorectal cancer. Biochem Biophys Res Commun 2014; 446:596-601. [PMID: 24632202 DOI: 10.1016/j.bbrc.2014.03.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Accepted: 03/04/2014] [Indexed: 11/22/2022]
Abstract
In the United States, there will be an estimated 96,830 new cases of colorectal cancer (CRC) and 50,310 deaths in 2014. CRC is often detected at late stages of the disease, at which point there is no effective chemotherapy. Thus, there is an urgent need for effective novel therapies that have minimal effects on normal cells. T-oligo, an oligonucleotide homologous to the 3'-telomere overhang, induces potent DNA damage responses in multiple malignant cell types, however, its efficacy in CRC has not been studied. This is the first investigation demonstrating T-oligo-induced anticancer effects in two CRC cell lines, HT-29 and LoVo, which are highly resistant to conventional chemotherapies. In this investigation, we show that T-oligo may mediate its DNA damage responses through the p53/p73 pathway, thereby inhibiting cellular proliferation and inducing apoptosis or senescence. Additionally, upregulation of downstream DNA damage response proteins, including E2F1, p53 or p73, was observed. In LoVo cells, T-oligo induced senescence, decreased clonogenicity, and increased expression of senescence associated proteins p21, p27, and p53. In addition, downregulation of POT1 and TRF2, two components of the shelterin protein complex which protects telomeric ends, was observed. Moreover, we studied the antiproliferative effects of T-oligo in combination with an EGFR tyrosine kinase inhibitor, Gefitinib, which resulted in an additive inhibitory effect on cellular proliferation. Collectively, these data provide evidence that T-oligo alone, or in combination with other molecularly targeted therapies, has potential as an anti-cancer agent in CRC.
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