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Ding S, Li S, Zhang S, Li Y. Genetic Alterations and Checkpoint Expression: Mechanisms and Models for Drug Discovery. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1248:227-250. [PMID: 32185713 DOI: 10.1007/978-981-15-3266-5_10] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
In this chapter, we will sketch a story that begins with the breakdown of chromosome homeostasis and genomic stability. Genomic alterations may render tumor cells eternal life at the expense of immunogenicity. Although antitumor immunity can be primed through neoantigens or inflammatory signals, tumor cells have evolved countermeasures to evade immune surveillance and strike back by modulating immune checkpoint related pathways. At present, monoclonal antibody drugs targeting checkpoints like PD-1 and CTLA-4 have significantly prolonged the survival of a variety of cancer patients, and thus have marked a great achievement in the history of antitumor therapy. Nevertheless, this is not the end of the story. As the relationship between genomic alteration and checkpoint expression is being delineated though the advances of preclinical animal models and emerging technologies, novel checkpoint targets are on the way to be discovered.
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Affiliation(s)
- Shuai Ding
- The State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Department of Rheumatology and Immunology, the Affiliated Drum Tower Hospital of Nanjing University Medical School, Model Animal Research Center of Nanjing University, Nanjing, Jiangsu, 210061, China
| | - Siqi Li
- The State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Department of Rheumatology and Immunology, the Affiliated Drum Tower Hospital of Nanjing University Medical School, Model Animal Research Center of Nanjing University, Nanjing, Jiangsu, 210061, China
| | - Shujie Zhang
- The State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Department of Rheumatology and Immunology, the Affiliated Drum Tower Hospital of Nanjing University Medical School, Model Animal Research Center of Nanjing University, Nanjing, Jiangsu, 210061, China
| | - Yan Li
- The State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Department of Rheumatology and Immunology, the Affiliated Drum Tower Hospital of Nanjing University Medical School, Model Animal Research Center of Nanjing University, Nanjing, Jiangsu, 210061, China.
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Meng X, Qi X, Guo H, Cai M, Li C, Zhu J, Chen F, Guo H, Li J, Zhao Y, Liu P, Jia X, Yu J, Zhang C, Sun W, Yu Y, Jin Y, Bai J, Wang M, Rosales J, Lee KY, Fu S. Novel role for non-homologous end joining in the formation of double minutes in methotrexate-resistant colon cancer cells. J Med Genet 2014; 52:135-44. [PMID: 25537274 PMCID: PMC4316941 DOI: 10.1136/jmedgenet-2014-102703] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Background Gene amplification is a frequent manifestation of genomic instability that plays a role in tumour progression and development of drug resistance. It is manifested cytogenetically as extrachromosomal double minutes (DMs) or intrachromosomal homogeneously staining regions (HSRs). To better understand the molecular mechanism by which HSRs and DMs are formed and how they relate to the development of methotrexate (MTX) resistance, we used two model systems of MTX-resistant HT-29 colon cancer cell lines harbouring amplified DHFR primarily in (i) HSRs and (ii) DMs. Results In DM-containing cells, we found increased expression of non-homologous end joining (NHEJ) proteins. Depletion or inhibition of DNA-PKcs, a key NHEJ protein, caused decreased DHFR amplification, disappearance of DMs, increased formation of micronuclei or nuclear buds, which correlated with the elimination of DHFR, and increased sensitivity to MTX. These findings indicate for the first time that NHEJ plays a specific role in DM formation, and that increased MTX sensitivity of DM-containing cells depleted of DNA-PKcs results from DHFR elimination. Conversely, in HSR-containing cells, we found no significant change in the expression of NHEJ proteins. Depletion of DNA-PKcs had no effect on DHFR amplification and resulted in only a modest increase in sensitivity to MTX. Interestingly, both DM-containing and HSR-containing cells exhibited decreased proliferation upon DNA-PKcs depletion. Conclusions We demonstrate a novel specific role for NHEJ in the formation of DMs, but not HSRs, in MTX-resistant cells, and that NHEJ may be targeted for the treatment of MTX-resistant colon cancer.
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Affiliation(s)
- Xiangning Meng
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China
| | - Xiuying Qi
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China
| | - Huanhuan Guo
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China
| | - Mengdi Cai
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China
| | - Chunxiang Li
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China
| | - Jing Zhu
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China
| | - Feng Chen
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China
| | - Huan Guo
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China
| | - Jie Li
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China
| | - Yuzhen Zhao
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China
| | - Peng Liu
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China
| | - Xueyuan Jia
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China
| | - Jingcui Yu
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China
| | - Chunyu Zhang
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China
| | - Wenjing Sun
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China
| | - Yang Yu
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China
| | - Yan Jin
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China Key Laboratory of Medical Genetics (Harbin Medical University), Heilongjiang Higher Education Institutions, Harbin, China
| | - Jing Bai
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China
| | - Mingrong Wang
- State Key Laboratory of Molecular Oncology, Cancer Institute (Hospital), Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China
| | - Jesusa Rosales
- Departments of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta, Canada
| | - Ki-Young Lee
- Cell Biology & Anatomy, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Songbin Fu
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, China Key Laboratory of Medical Genetics (Harbin Medical University), Heilongjiang Higher Education Institutions, Harbin, China
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Chronic myelogenous leukemia stem and progenitor cells demonstrate chromosomal instability related to repeated breakage-fusion-bridge cycles mediated by increased nonhomologous end joining. Blood 2012; 119:6187-97. [PMID: 22493298 DOI: 10.1182/blood-2011-05-352252] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Chromosomal aberrations are an important consequence of genotoxic exposure and contribute to pathogenesis and progression of several malignancies. We investigated the susceptibility to chromosomal aberrations in chronic myelogenous leukemia (CML) progenitors after exposure to ionizing radiation. In normal progenitors, ionizing radiation induced both stable and unstable chromosomal lesions, but only stable aberrations persisted after multiple divisions. In contrast, radiation of chronic phase CML progenitors resulted in enhanced generation of unstable lesions that persisted after multiple divisions. CML progenitors demonstrated active cell cycle checkpoints and increased nonhomologous end joining DNA repair, suggesting that persistence of unstable aberrations was the result of continued generation of these lesions. CML progenitors demonstrated enhanced susceptibility to repeated cycles of chromosome damage, repair, and damage through a breakage-fusion-bridge mechanism. Perpetuation of breakage-fusion-bridge cycles in CML progenitors was mediated by classic nonhomologous end joining repair. These studies reveal a previously unrecognized mechanism of chromosomal instability in leukemia progenitors because of continued generation of unstable chromosomal lesions through repeated cycles of breakage and repair of such lesions.
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Johannes C, Horstmann M, Durante M, Chudoba I, Obe G. Chromosome intrachanges and interchanges detected by multicolor banding in lymphocytes: searching for clastogen signatures in the human genome. Radiat Res 2004; 161:540-8. [PMID: 15161369 DOI: 10.1667/rr3157] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Genomic fingerprints of mutagenic agents would have wide applications in the field of cancer biology, epidemiology and prevention. The differential spectra of chromosomal aberrations induced by different clastogens suggest that ratios of specific aberrations can be exploited as biomarkers of carcinogen exposure. We have tested this hypothesis using the novel technique of multicolor banding in situ hybridization (mBAND) in human peripheral blood lymphocytes exposed in vitro to X rays, neutrons, heavy ions, or the restriction endonuclease AluI. In the heavy-ion-irradiated cells, we further analyzed aberrations in chromosome 5 using multicolor FISH (mFISH). Contrary to the expectations of biophysical models, our results do not support the use of the ratios of inter-/intrachromosomal exchanges or intra-/interarm intrachanges as fingerprints of exposure to densely ionizing radiation. However, our data point to measurable differences in the ratio of complex/simple interchanges after exposure to different clastogens. These data should be considered in current biophysical models of radiation action in living cells.
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Affiliation(s)
- C Johannes
- Department of Genetics, University of Duisburg-Essen, 45117 Essen, Germany
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