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Yu W, Gargett T, Du Z. A Poisson distribution-based general model of cancer rates and a cancer risk-dependent theory of aging. Aging (Albany NY) 2023; 15:8537-8551. [PMID: 37659107 PMCID: PMC10522393 DOI: 10.18632/aging.205016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Accepted: 08/20/2023] [Indexed: 09/04/2023]
Abstract
This article presents a formula for modeling the lifetime incidence of cancer in humans. The formula utilizes a Poisson distribution-based "np" model to predict cancer incidence, with "n" representing the effective number of cell turnover and "p" representing the probability of single-cell transformation. The model accurately predicts the observed incidence of cancer in humans when a reduction in cell turnover due to aging is taken into account. The model also suggests that cancer development is ultimately inevitable. The article proposes a theory of aging based on this concept, called the "np" theory. According to this theory, an organism maintains its order by balancing cellular entropy through continuous proliferation. However, cellular "information entropy" in the form of accumulated DNA mutations increases irreversibly over time, restricting the total number of cells an organism can generate throughout its lifetime. When cell division slows down and fails to compensate for the increased entropy in the system, aging occurs. Essentially, aging is the phenomenon of running out of predetermined cell resources. Different species have evolved separate strategies to utilize their limited cell resources throughout their life cycle.
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Affiliation(s)
- Wenbo Yu
- Centre for Cancer Biology, SA Pathology and University of South Australia, Adelaide, SA, Australia
- Cancer Clinical Trials Unit, Royal Adelaide Hospital, Adelaide, SA, Australia
- School of Medicine, The University of Adelaide, Adelaide, SA, Australia
| | - Tessa Gargett
- Centre for Cancer Biology, SA Pathology and University of South Australia, Adelaide, SA, Australia
- Cancer Clinical Trials Unit, Royal Adelaide Hospital, Adelaide, SA, Australia
- School of Medicine, The University of Adelaide, Adelaide, SA, Australia
| | - Zhenglong Du
- Department of Molecular and Biomedical Science, School of Biological Sciences, The University of Adelaide, Adelaide, SA, Australia
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2
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Bieuville M, Tissot T, Robert A, Henry P, Pavard S. Modeling of senescent cell dynamics predicts a late‐life decrease in cancer incidence. Evol Appl 2023; 16:609-624. [PMID: 36969142 PMCID: PMC10033854 DOI: 10.1111/eva.13514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 10/31/2022] [Accepted: 11/07/2022] [Indexed: 03/05/2023] Open
Abstract
Current oncogenic theories state that tumors arise from cell lineages that sequentially accumulate (epi)mutations, progressively turning healthy cells into carcinogenic ones. While those models found some empirical support, they are little predictive of intraspecies age-specific cancer incidence and of interspecies cancer prevalence. Notably, in humans and lab rodents, a deceleration (and sometimes decline) of cancer incidence rate has been found at old ages. Additionally, dominant theoretical models of oncogenesis predict that cancer risk should increase in large and/or long-lived species, which is not supported by empirical data. Here, we explore the hypothesis that cellular senescence could explain those incongruent empirical patterns. More precisely, we hypothesize that there is a trade-off between dying of cancer and of (other) ageing-related causes. This trade-off between organismal mortality components would be mediated, at the cellular scale, by the accumulation of senescent cells. In this framework, damaged cells can either undergo apoptosis or enter senescence. Apoptotic cells lead to compensatory proliferation, associated with an excess risk of cancer, whereas senescent cell accumulation leads to ageing-related mortality. To test our framework, we build a deterministic model that first describes how cells get damaged, undergo apoptosis, or enter senescence. We then translate those cellular dynamics into a compound organismal survival metric also integrating life-history traits. We address four different questions linked to our framework: can cellular senescence be adaptive, do the predictions of our model reflect epidemiological patterns observed among mammal species, what is the effect of species sizes on those answers, and what happens when senescent cells are removed? Importantly, we find that cellular senescence can optimize lifetime reproductive success. Moreover, we find that life-history traits play an important role in shaping the cellular trade-offs. Overall, we demonstrate that integrating cellular biology knowledge with eco-evolutionary principles is crucial to solve parts of the cancer puzzle.
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Affiliation(s)
- Margaux Bieuville
- Eco‐Anthropologie (EA UMR 7206), MNHN, CNRS Université Paris‐Diderot Paris France
| | - Tazzio Tissot
- Agent, Interaction and complexity (AIC) research group Southampton University Southampton UK
| | - Alexandre Robert
- Centre d'Ecologie et des Sciences de la Conservation (CESCO UMR 7204), MNHN, CNRS Sorbonne Université Paris France
| | - Pierre‐Yves Henry
- Mécanismes Adaptatifs et Evolution (MECADEV UMR 7179), MNHN, CNRS Brunoy France
| | - Samuel Pavard
- Eco‐Anthropologie (EA UMR 7206), MNHN, CNRS Université Paris‐Diderot Paris France
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3
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Bentley MA, Yates CA, Hein J, Preston GM, Foster KR. Pleiotropic constraints promote the evolution of cooperation in cellular groups. PLoS Biol 2022; 20:e3001626. [PMID: 35658016 PMCID: PMC9166655 DOI: 10.1371/journal.pbio.3001626] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 04/11/2022] [Indexed: 12/12/2022] Open
Abstract
The evolution of cooperation in cellular groups is threatened by lineages of cheaters that proliferate at the expense of the group. These cell lineages occur within microbial communities, and multicellular organisms in the form of tumours and cancer. In contrast to an earlier study, here we show how the evolution of pleiotropic genetic architectures—which link the expression of cooperative and private traits—can protect against cheater lineages and allow cooperation to evolve. We develop an age-structured model of cellular groups and show that cooperation breaks down more slowly within groups that tie expression to a private trait than in groups that do not. We then show that this results in group selection for pleiotropy, which strongly promotes cooperation by limiting the emergence of cheater lineages. These results predict that pleiotropy will rapidly evolve, so long as groups persist long enough for cheater lineages to threaten cooperation. Our results hold when pleiotropic links can be undermined by mutations, when pleiotropy is itself costly, and in mixed-genotype groups such as those that occur in microbes. Finally, we consider features of multicellular organisms—a germ line and delayed reproductive maturity—and show that pleiotropy is again predicted to be important for maintaining cooperation. The study of cancer in multicellular organisms provides the best evidence for pleiotropic constraints, where abberant cell proliferation is linked to apoptosis, senescence, and terminal differentiation. Alongside development from a single cell, we propose that the evolution of pleiotropic constraints has been critical for cooperation in many cellular groups. The evolution of cooperation in cellular groups is threatened by lineages of cheaters that proliferate at the expense of the group. In this study, an age-structured model of cellular groups shows that pleiotropy promotes the evolution of cooperation and may have been important for the origins of multicellularity.
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Affiliation(s)
- Michael A. Bentley
- Department of Zoology, University of Oxford, Oxford, United Kingdom
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
- * E-mail: (MAB); (KRF)
| | - Christian A. Yates
- Department of Mathematical Sciences, University of Bath, Bath, United Kingdom
| | - Jotun Hein
- Department of Statistics, University of Oxford, Oxford, United Kingdom
| | - Gail M. Preston
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
| | - Kevin R. Foster
- Department of Zoology, University of Oxford, Oxford, United Kingdom
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
- * E-mail: (MAB); (KRF)
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4
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Matsuda Y, Yamashita T, Ye J, Yasukawa M, Yamakawa K, Mukai Y, Machitani M, Daigo Y, Miyagi Y, Yokose T, Oshima T, Ito H, Morinaga S, Kishida T, Minamoto T, Yamada S, Takei J, Kaneko MK, Kojima M, Kaneko S, Masaki T, Hirata M, Haba R, Kontani K, Kanaji N, Miyatake N, Okano K, Kato Y, Masutomi K. Phosphorylation of
hTERT
at threonine 249 is a novel tumor biomarker of aggressive cancer with poor prognosis in multiple organs. J Pathol 2022; 257:172-185. [PMID: 35094384 PMCID: PMC9315154 DOI: 10.1002/path.5876] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 01/21/2022] [Accepted: 01/25/2022] [Indexed: 11/07/2022]
Abstract
Recent evidence indicates that RNA‐dependent RNA polymerase (RdRP) activity of human telomerase reverse transcriptase (hTERT) regulates expression of target genes and is directly involved in tumor formation in a telomere‐independent manner. Non‐canonical function of hTERT has been considered as a therapeutic target for cancer therapy. We have previously shown that hTERT phosphorylation at threonine 249 (p‐hTERT), which promotes RdRP activity, is an indicator of an aggressive phenotype and poor prognosis in liver and pancreatic cancers, using two cohorts with small sample sizes with polyclonal p‐hTERT antibody. To clarify the clinical relevance of p‐hTERT, we developed a specific monoclonal antibody and determined the diagnostic and prognostic value of p‐hTERT in cancer specimens using a large cohort. A monoclonal antibody for phosphorylated hTERT (p‐hTERT) at threonine 249 was developed and validated. The antibody was used for the immunohistochemical staining of formalin‐fixed, paraffin‐embedded specimens from 1523 cases of lung, colon, stomach, pancreatic, liver, breast, and kidney cancers. We detected elevated p‐hTERT expression levels in cases with a high mitotic activity, high pathological grade, and high nuclear pleomorphism. Elevated p‐hTERT expression was an independent prognostic factor for lung, pancreatic, and liver cancers. Furthermore, p‐hTERT expression was associated with immature and aggressive features, such as adenosquamous carcinoma (lung and pancreas), invasive type of cancer (lung), high serum alpha‐fetoprotein level (liver), and triple‐negative status (breast). In conclusion, RdRP activity indicated by p‐hTERT expression predicts aggressive cancer phenotypes in various types of cancer. Thus, p‐hTERT is a novel biomarker for the diagnosis of aggressive cancers with a poor prognosis. © 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.
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Affiliation(s)
- Yoko Matsuda
- Oncology Pathology, Department of Pathology and Host‐Defense, Faculty of Medicine Kagawa University, 1750‐1 Ikenobe, Miki‐cho Kita‐gun Kagawa 761‐0793 Japan
| | - Taro Yamashita
- Department of Gastroenterology Kanazawa University Graduate School of Medical Sciences 13‐1 Takara‐machi Kanazawa Ishikawa 920‐8641 Japan
| | - Juanjuan Ye
- Oncology Pathology, Department of Pathology and Host‐Defense, Faculty of Medicine Kagawa University, 1750‐1 Ikenobe, Miki‐cho Kita‐gun Kagawa 761‐0793 Japan
| | - Mami Yasukawa
- Division of Cancer Stem Cell National Cancer Center Research Institute 5‐1‐1 Tsukiji, Chuo‐ku Tokyo 104‐0045 Japan
| | - Keiko Yamakawa
- Oncology Pathology, Department of Pathology and Host‐Defense, Faculty of Medicine Kagawa University, 1750‐1 Ikenobe, Miki‐cho Kita‐gun Kagawa 761‐0793 Japan
| | - Yuri Mukai
- Oncology Pathology, Department of Pathology and Host‐Defense, Faculty of Medicine Kagawa University, 1750‐1 Ikenobe, Miki‐cho Kita‐gun Kagawa 761‐0793 Japan
| | - Mitsuhiro Machitani
- Division of Cancer Stem Cell National Cancer Center Research Institute 5‐1‐1 Tsukiji, Chuo‐ku Tokyo 104‐0045 Japan
| | - Yataro Daigo
- Department of Medical Oncology and Cancer Center
- Center for Advanced Medicine against Cancer, Shiga University of Medical Science Otsu Shiga 520‐2192 Japan
- Center for Antibody and Vaccine Therapy, Research Hospital, Institute of Medical Science Hospital, The University of Tokyo Tokyo 108‐8639 Japan
| | - Yohei Miyagi
- Kanagawa Cancer Center Research Institute, 2‐3‐2 Nakao, Asahi‐ku Yokohama 241‐8515 Japan
| | | | | | | | | | - Takeshi Kishida
- Department of Urology, Kanagawa Cancer Center, 2‐3‐2 Nakao, Asahi‐ku Yokohama 241‐8515 Japan
| | - Toshinari Minamoto
- Divison of Translational and Clinical Oncology, Cancer Research Institute, Kanazawa University, 13‐1 Takara‐machi Kanazawa 920‐0934 Japan
| | - Shinji Yamada
- Department of Antibody Drug Development Tohoku University Graduate School of Medicine, 2‐1 Seiryo‐machi, Aoba‐ku Sendai Miyagi 980‐8575 Japan
| | - Junko Takei
- Department of Antibody Drug Development Tohoku University Graduate School of Medicine, 2‐1 Seiryo‐machi, Aoba‐ku Sendai Miyagi 980‐8575 Japan
| | - Mika K. Kaneko
- Department of Antibody Drug Development Tohoku University Graduate School of Medicine, 2‐1 Seiryo‐machi, Aoba‐ku Sendai Miyagi 980‐8575 Japan
| | - Motohiro Kojima
- Division of Pathology, Exploratory Oncology Research and Clinical Trial Center, National Cancer Center, 6‐5‐1 Kashiwanoha, Kashiwa‐shi Chiba 277‐0882 Japan
| | - Shuichi Kaneko
- Department of Gastroenterology Kanazawa University Graduate School of Medical Sciences 13‐1 Takara‐machi Kanazawa Ishikawa 920‐8641 Japan
| | | | | | | | | | - Nobuhiro Kanaji
- Department of Internal Medicine, Division of Hematology Rheumatology and Respiratory Medicine
| | | | - Keiichi Okano
- Department of Gastroenterological Surgery, Faculty of Medicine Kagawa University, 1750‐1 Ikenobe, Miki‐cho Kita‐gun Kagawa 761‐0793 Japan
| | - Yukinari Kato
- Department of Antibody Drug Development Tohoku University Graduate School of Medicine, 2‐1 Seiryo‐machi, Aoba‐ku Sendai Miyagi 980‐8575 Japan
- Department of Molecular Pharmacology Tohoku University Graduate School of Medicine, 2‐1 Seiryo‐machi, Aoba‐ku Sendai Miyagi 980‐8575 Japan
| | - Kenkichi Masutomi
- Division of Cancer Stem Cell National Cancer Center Research Institute 5‐1‐1 Tsukiji, Chuo‐ku Tokyo 104‐0045 Japan
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Gatenby RA, Avdieiev S, Tsai KY, Brown JS. Integrating genetic and nongenetic drivers of somatic evolution during carcinogenesis: The biplane model. Evol Appl 2020; 13:1651-1659. [PMID: 32952610 PMCID: PMC7484850 DOI: 10.1111/eva.12973] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Revised: 03/26/2020] [Accepted: 03/30/2020] [Indexed: 12/12/2022] Open
Abstract
The multistep transition from a normal to a malignant cellular phenotype is often termed "somatic evolution" caused by accumulating random mutations. Here, we propose an alternative model in which the initial genetic state of a cancer cell is the result of mutations that occurred throughout the lifetime of the host. However, these mutations are not carcinogenic because normal cells in multicellular organism cannot ordinarily evolve. That is, proliferation and death of normal cells are controlled by local tissue constraints typically governed by nongenomic information dynamics in the cell membrane. As a result, the cells of a multicellular organism have a fitness that is identical to the host, which is then the unit of natural selection. Somatic evolution of a cell can occur only when its fate becomes independent of host constraints. Now, survival, proliferation, and death of individual cells are dependent on Darwinian dynamics. This cellular transition from host-defined fitness to self-defined fitness may, consistent with the conventional view of carcinogenesis, result from mutations that render the cell insensitive to host controls. However, an identical state will result when surrounding tissue cannot exert control because of injury, inflammation, aging, or infection. Here, all surviving cells within the site of tissue damage default to self-defined fitness functions allowing them to evolve so that the mutations accumulated over the lifetime of the host now serve as the genetic heritage of an evolutionary unit of selection. Furthermore, tissue injury generates a new ecology cytokines and growth factors that might promote proliferation in cells with prior receptor mutations. This model integrates genetic and nongenetic dynamics into cancer development and is consistent with both clinical observations and prior experiments that divided carcinogenesis to initiation, promotion, and progression steps.
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Affiliation(s)
| | | | - Kenneth Y. Tsai
- Cancer Biology and Evolution ProgramMoffitt Cancer CenterTampaFLUSA
| | - Joel S. Brown
- Cancer Biology and Evolution ProgramMoffitt Cancer CenterTampaFLUSA
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7
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Suárez Fernández JP. The downfall of the linear non-threshold model. Rev Esp Med Nucl Imagen Mol 2020; 39:303-315. [PMID: 32693978 DOI: 10.1016/j.remn.2020.05.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 05/24/2020] [Accepted: 05/25/2020] [Indexed: 12/19/2022]
Abstract
The linear non-threshold model (LNTM) is a theoretical dose-response function as a result of extrapolating the late effects of high-dose exposure to ionizing radiation to the low-dose range, but there is great uncertainty about its validity. The acceptance of LNTM as the dominant probabilistic model have survived to the present day and it is actually the cornerstone of current radiation protection policies. In the last decades, advances in molecular and evolutive biology, cancer immunology, and many epidemiological and animal studies have cast serious doubts about the reliability of the NLTM, as well as suggesting alternative models, like the hormetic theory. Considering the given evidences, a discussion between the involved scientific societies and the regulatory commissions is promtly required in order to to reach a redefiniton of theradiation protection basis, as it would be specially crucial in the medical field.
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Affiliation(s)
- J P Suárez Fernández
- Servicio de Medicina Nuclear, Hospital Universitario Central de Asturias, Oviedo, Asturias, España.
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8
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Age-Related and Gender-Related Increases in Colorectal Cancer Mortality Rates in Brazil Between 1979 and 2015: Projections for Continuing Rises in Disease. J Gastrointest Cancer 2020; 52:280-288. [PMID: 32248507 PMCID: PMC7900022 DOI: 10.1007/s12029-020-00399-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Purpose Brazil is the largest country in South America. Although a developing nation, birth rates have been decreasing in the last few decades, while its overall population is undergoing lifestyle changes and ageing significantly. Moreover, Brazil has had increasingly high mortality rates related to colorectal cancer (CRC). Herein, we investigated whether the Brazilian population is exhibiting increasing mortality rates related to colon cancer (CC) or rectal cancer (RC) in recent years. Methods We examined data from the Brazilian Federal Government from 1979 to 2015 to determine whether CRC mortality and the population ageing process may be associated. Results Our mathematical modelling suggests that mortality rates related to CC and RC events in the Brazilian population may increase by 79% and 66% in the next 24 years, respectively. This finding led us to explore the mortality rates for both diseases in the country, and we observed that the highest levels were in the south and southeast regions from the year 2000 onwards. CC events appear to decrease life expectancy among people during their second decade of life in recent years, whereas RC events induced decreases in life expectancy in those aged >30 years. Additionally, both CC and RC events seem to promote significant mortality rates in the male population aged > 60 years and living in the southern states. Conclusion Our dataset suggests that both CC and RC events may lead to a significantly increasing number of deaths in the Brazilian male population in coming years.
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Kattner P, Strobel H, Khoshnevis N, Grunert M, Bartholomae S, Pruss M, Fitzel R, Halatsch ME, Schilberg K, Siegelin MD, Peraud A, Karpel-Massler G, Westhoff MA, Debatin KM. Compare and contrast: pediatric cancer versus adult malignancies. Cancer Metastasis Rev 2020; 38:673-682. [PMID: 31832830 DOI: 10.1007/s10555-019-09836-y] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Cancer is a leading cause of death in both adults and children, but in terms of absolute numbers, pediatric cancer is a relatively rare disease. The rarity of pediatric cancer is consistent with our current understanding of how adult malignancies form, emphasizing the view of cancer as a genetic disease caused by the accumulation and selection of unrepaired mutations over time. However, considering those children who develop cancer merely as stochastically "unlucky" does not fully explain the underlying aetiology, which is distinct from that observed in adults. Here, we discuss the differences in cancer genetics, distribution, and microenvironment between adult and pediatric cancers and argue that pediatric tumours need to be seen as a distinct subset with their own distinct therapeutic challenges. While in adults, the benefit of any treatment should outweigh mostly short-term complications, potential long-term effects have a much stronger impact in children. In addition, clinical trials must cope with low participant numbers when evaluating novel treatment strategies, which need to address the specific requirements of children.
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Affiliation(s)
- Patricia Kattner
- Department of Pediatrics and Adolescent Medicine, University Medical Center Ulm, Eythstrasse 24, 89075, Ulm, Germany
| | - Hannah Strobel
- Department of Pediatrics and Adolescent Medicine, University Medical Center Ulm, Eythstrasse 24, 89075, Ulm, Germany
| | - Nika Khoshnevis
- Department of Pediatrics and Adolescent Medicine, University Medical Center Ulm, Eythstrasse 24, 89075, Ulm, Germany
| | - Michael Grunert
- Department of Radiology, German Armed Forces Hospital of Ulm, Ulm, Germany
| | - Stephan Bartholomae
- Department of Pediatrics and Adolescent Medicine, University Medical Center Ulm, Eythstrasse 24, 89075, Ulm, Germany
| | - Maximilian Pruss
- Department of Neurosurgery, University Medical Center Ulm, Ulm, Germany
| | - Rahel Fitzel
- Department of Pediatrics and Adolescent Medicine, University Medical Center Ulm, Eythstrasse 24, 89075, Ulm, Germany
| | | | | | - Markus D Siegelin
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY, USA
| | - Aurelia Peraud
- Pediatric Neurosurgery Section, Department of Neurosurgery, University Medical Center Ulm, Ulm, Germany
| | | | - Mike-Andrew Westhoff
- Department of Pediatrics and Adolescent Medicine, University Medical Center Ulm, Eythstrasse 24, 89075, Ulm, Germany.
| | - Klaus-Michael Debatin
- Department of Pediatrics and Adolescent Medicine, University Medical Center Ulm, Eythstrasse 24, 89075, Ulm, Germany
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10
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Laconi E, Marongiu F, DeGregori J. Cancer as a disease of old age: changing mutational and microenvironmental landscapes. Br J Cancer 2020; 122:943-952. [PMID: 32042067 PMCID: PMC7109142 DOI: 10.1038/s41416-019-0721-1] [Citation(s) in RCA: 134] [Impact Index Per Article: 33.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 12/09/2019] [Accepted: 12/19/2019] [Indexed: 01/27/2023] Open
Abstract
Why do we get cancer mostly when we are old? According to current paradigms, the answer is simple: mutations accumulate in our tissues throughout life, and some of these mutations contribute to cancers. Although mutations are necessary for cancer development, a number of studies shed light on roles for ageing and exposure-dependent changes in tissue landscapes that determine the impact of oncogenic mutations on cellular fitness, placing carcinogenesis into an evolutionary framework. Natural selection has invested in somatic maintenance to maximise reproductive success. Tissue maintenance not only ensures functional robustness but also prevents the occurrence of cancer through periods of likely reproduction by limiting selection for oncogenic events in our cells. Indeed, studies in organisms ranging from flies to humans are revealing conserved mechanisms to eliminate damaged or oncogenically initiated cells from tissues. Reports of the existence of striking numbers of oncogenically initiated clones in normal tissues and of how this clonal architecture changes with age or external exposure to noxious substances provide critical insight into the early stages of cancer development. A major challenge for cancer biology will be the integration of these studies with epidemiology data into an evolutionary theory of carcinogenesis, which could have a large impact on addressing cancer risk and treatment.
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Affiliation(s)
- Ezio Laconi
- Department of Biomedical Sciences, Section of Pathology, University of Cagliari School of Medicine, 09126, Cagliari, Italy.
| | - Fabio Marongiu
- Department of Biomedical Sciences, Section of Pathology, University of Cagliari School of Medicine, 09126, Cagliari, Italy
| | - James DeGregori
- Department of Biochemistry and Molecular Genetics, Integrated Department of Immunology, Department of Pediatrics, Department of Medicine (Section of Hematology), University of Colorado Anschutz Medical Campus, Aurora, CO, 80045, USA.
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11
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Vidal P. Interferon α in cancer immunoediting: From elimination to escape. Scand J Immunol 2020; 91:e12863. [PMID: 31909839 DOI: 10.1111/sji.12863] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 11/11/2019] [Accepted: 01/03/2020] [Indexed: 12/25/2022]
Abstract
Interferon α (IFNα) is a cytokine that mediates diverse immune responses to tumours. It is the oldest immune-based oncologic drug and has been widely used to treat various malignancies in humans. Yet, the use of IFNα in cancer therapy has only resulted in limited success and even led to worse clinical outcomes under certain instances. The emergence of the cancer immunoediting concept-which implicates the host immune system in promoting tumour growth-recapitulates the need to evaluate the immune functions of IFNα. This review proposes that IFNα has dual opposing roles in cancer development based on the mutational status of its signalling components, which determines the expression of anti- or pro-tumorigenic IFN-stimulated genes (ISGs). This duality may translate into new applications of IFNα in cancer immunotherapy.
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Affiliation(s)
- Paolo Vidal
- Department of Medical Microbiology, College of Public Health, University of the Philippines Manila, Philippines
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12
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Chen B, Shi Z, Chen Q, Shen X, Shibata D, Wen H, Wu CI. Tumorigenesis as the Paradigm of Quasi-neutral Molecular Evolution. Mol Biol Evol 2020; 36:1430-1441. [PMID: 30912799 DOI: 10.1093/molbev/msz075] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
In the absence of both positive and negative selections, coding sequences evolve at a neutral rate (R = 1). Such a high genomic rate is generally not achievable due to the prevalence of negative selection against codon substitutions. Remarkably, somatic evolution exhibits the seemingly neutral rate R ∼ 1 across normal and cancerous tissues. Nevertheless, R ∼ 1 may also mean that positive and negative selections are both strong, but equal in intensity. We refer to this regime as quasi-neutral. Indeed, individual genes in cancer cells often evolve at a much higher, or lower, rate than R ∼ 1. Here, we show that 1) quasi-neutrality is much more likely when populations are small (N < 50); 2) stem-cell populations in single normal tissue niches, from which tumors likely emerge, have a small N (usually <50) but selection at this stage is measurable and strong; 3) when N dips below 50, selection efficacy decreases precipitously; and 4) notably, N is smaller in the stem-cell niche of the small intestine than in the colon. Hence, the ∼70-fold higher rate of phenotypic evolution (observed as cancer risk) in the latter can be explained by the greater efficacy of selection, which then leads to the fixation of more advantageous and fewer deleterious mutations in colon cancers. In conclusion, quasi-neutral evolution sheds a new light on a general evolutionary principle that helps to explain aspects of cancer evolution.
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Affiliation(s)
- Bingjie Chen
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Zongkun Shi
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Qingjian Chen
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Xu Shen
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Darryl Shibata
- Department of Pathology, Keck School of Medicine of the University of Southern California, Los Angeles, CA
| | - Haijun Wen
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Chung-I Wu
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China.,CAS Key Laboratory of Genomic and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, China.,Department of Ecology and Evolution, University of Chicago, Chicago, IL
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Evans JJ, Alkaisi MM, Sykes PH. Tumour Initiation: a Discussion on Evidence for a "Load-Trigger" Mechanism. Cell Biochem Biophys 2019; 77:293-308. [PMID: 31598831 PMCID: PMC6841748 DOI: 10.1007/s12013-019-00888-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Accepted: 09/23/2019] [Indexed: 12/18/2022]
Abstract
Appropriate mechanical forces on cells are vital for normal cell behaviour and this review discusses the possibility that tumour initiation depends partly on the disruption of the normal physical architecture of the extracellular matrix (ECM) around a cell. The alterations that occur thence promote oncogene expression. Some questions, that are not answered with certainty by current consensus mechanisms of tumourigenesis, are elegantly explained by the triggering of tumours being a property of the physical characteristics of the ECM, which is operative following loading of the tumour initiation process with a relevant gene variant. Clinical observations are consistent with this alternative hypothesis which is derived from studies that have, together, accumulated an extensive variety of data incorporating biochemical, genetic and clinical findings. Thus, this review provides support for the view that the ECM may have an executive function in induction of a tumour. Overall, reported observations suggest that either restoring an ECM associated with homeostasis or targeting the related signal transduction mechanisms may possibly be utilised to modify or control the early progression of cancers. The review provides a coherent template for discussing the notion, in the context of contemporary knowledge, that tumourigenesis is an alliance of biochemistry, genetics and biophysics, in which the physical architecture of the ECM may be a fundamental component. For more definitive clarification of the concept there needs to be a phalanx of experiments conceived around direct questions that are raised by this paper.
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Affiliation(s)
- John J Evans
- Department of Obstetrics and Gynaecology, University of Otago Christchurch, Christchurch, New Zealand.
- MacDiarmid Institute of Advanced Materials and Nanotechnology, Christchurch, New Zealand.
| | - Maan M Alkaisi
- MacDiarmid Institute of Advanced Materials and Nanotechnology, Christchurch, New Zealand
- Department of Electrical and Computer Engineering, University of Canterbury, Christchurch, New Zealand
| | - Peter H Sykes
- Department of Obstetrics and Gynaecology, University of Otago Christchurch, Christchurch, New Zealand
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14
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Golubev AG, Anisimov VN. Aging and cancer: Is glucose a mediator between them? Oncotarget 2019; 10:6758-6767. [PMID: 31827719 PMCID: PMC6887572 DOI: 10.18632/oncotarget.27344] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 11/07/2019] [Indexed: 02/07/2023] Open
Abstract
Aging can increase cancer incidence because of accumulated mutations that initiate cancer and via compromised body control of premalignant lesions development into cancer. Relative contributions of these two factors are debated. Recent evidence suggests that the latter is rate limiting. In particular, hyperglycemia caused by compromised body control of blood glucose may be a factor of selection of somatic mutation-bearing cells for the ability to use glucose for proliferation. High glucose utilization in aerobic glycolysis is a long known characteristic of cancer. The new evidence adds to the concepts that have been being developed starting from mid-1970ies to suggest that age-related shifts in glucose and lipid metabolism increase the risk of cancer and compromise prognoses for cancer patients and to propose antidiabetic biguanides, including metformin, for cancer prevention and as an adjuvant means of cancer treatment aimed at the metabolic rehabilitation of patients. The new evidence is consistent with several effects of glucose contributing to aging and acting synergistically to enhance carcinogenesis. Glucose can affect (i) separate cells (via promoting somatic mutagenesis and epigenetic instability), (ii) cell populations (via being a factor of selection of phenotypic variants in cell populations for higher glucose consumption and, ultimately, for high aerobic glycolysis); (iii) cell microenvironment (via modification of extracellular matrix proteins), and (iv) the systemic levels (via shifting the endocrine regulation of metabolism toward increasing blood lipids and body fat, which compromise immunological surveillance and promote inflammation). Thus, maintenance of youthful metabolic characteristics must be important for cancer prevention and treatment.
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Affiliation(s)
- Alexey G. Golubev
- Department of Carcinogenesis and Oncogerontology, N.N. Petrov National Medical Research Center of Oncology, Saint Petersburg 197758, Russia
| | - Vladimir N. Anisimov
- Department of Carcinogenesis and Oncogerontology, N.N. Petrov National Medical Research Center of Oncology, Saint Petersburg 197758, Russia
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15
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A Critical Assessment of the Linear No-Threshold Hypothesis: Its Validity and Applicability for Use in Risk Assessment and Radiation Protection. Clin Nucl Med 2019; 44:521-525. [PMID: 31107746 DOI: 10.1097/rlu.0000000000002613] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The Society of Nuclear Medicine and Molecular Imaging convened a task group to examine the evidence for the risk of carcinogenesis from low-dose radiation exposure and to assess evidence in the scientific literature related to the overall validity of the linear no-threshold (LNT) hypothesis and its applicability for use in risk assessment and radiation protection. In the low-dose and dose-rate region, the group concluded that the LNT hypothesis is invalid as it is not supported by the available scientific evidence and, instead, is actually refuted by published epidemiology and radiation biology. The task group concluded that the evidence does not support the use of LNT either for risk assessment or radiation protection in the low-dose and dose-rate region.
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16
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Matsuda Y. Age-related morphological changes in the pancreas and their association with pancreatic carcinogenesis. Pathol Int 2019; 69:450-462. [PMID: 31339204 DOI: 10.1111/pin.12837] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2019] [Accepted: 06/26/2019] [Indexed: 12/14/2022]
Abstract
Age-related pathological changes in the pancreas have been unclear because they are often minor and nonspecific. However, recent studies have shown that they are closely related to various pathological conditions such as pancreatic cancer and diabetes mellitus. Knowledge of age-related changes is important to determine appropriate prevention, detection, and treatment strategies for various diseases observed in elderly patients. We present a review of the pathological age-related non-neoplastic changes in the exocrine pancreas such as pancreatic fatty replacement, lobulocentric pancreatic atrophy, pancreatic duct ectasia, and metaplasia of exocrine pancreas, as well as changes in islet cells. We have discussed common pancreatic neoplasms in elderly patients, such as pancreatic intraepithelial neoplasia (PanIN), intraductal papillary mucinous neoplasms (IPMNs), and pancreatic ductal adenocarcinoma (PDAC). Age-related pathological changes play a key role in pancreatic carcinogenesis via telomere dysfunction. Further studies are warranted to clarify molecular mechanisms of pancreatic carcinogenesis in elderly patients.
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Affiliation(s)
- Yoko Matsuda
- Department of Pathology and Host-Defense, Faculty of Medicine, Kagawa University, Kagawa, Japan
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17
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Enforcement is central to the evolution of cooperation. Nat Ecol Evol 2019; 3:1018-1029. [PMID: 31239554 DOI: 10.1038/s41559-019-0907-1] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Accepted: 04/26/2019] [Indexed: 01/21/2023]
Abstract
Cooperation occurs at all levels of life, from genomes, complex cells and multicellular organisms to societies and mutualisms between species. A major question for evolutionary biology is what these diverse systems have in common. Here, we review the full breadth of cooperative systems and find that they frequently rely on enforcement mechanisms that suppress selfish behaviour. We discuss many examples, including the suppression of transposable elements, uniparental inheritance of mitochondria and plastids, anti-cancer mechanisms, reciprocation and punishment in humans and other vertebrates, policing in eusocial insects and partner choice in mutualisms between species. To address a lack of accompanying theory, we develop a series of evolutionary models that show that the enforcement of cooperation is widely predicted. We argue that enforcement is an underappreciated, and often critical, ingredient for cooperation across all scales of biological organization.
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18
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Ujvari B, Klaassen M, Raven N, Russell T, Vittecoq M, Hamede R, Thomas F, Madsen T. Genetic diversity, inbreeding and cancer. Proc Biol Sci 2019; 285:rspb.2017.2589. [PMID: 29563261 DOI: 10.1098/rspb.2017.2589] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 02/28/2018] [Indexed: 12/13/2022] Open
Abstract
Genetic diversity is essential for adaptive capacities, providing organisms with the potential of successfully responding to intrinsic and extrinsic challenges. Although a clear reciprocal link between genetic diversity and resistance to parasites and pathogens has been established across taxa, the impact of loss of genetic diversity by inbreeding on the emergence and progression of non-communicable diseases, such as cancer, has been overlooked. Here we provide an overview of such associations and show that low genetic diversity and inbreeding associate with an increased risk of cancer in both humans and animals. Cancer being a multifaceted disease, loss of genetic diversity can directly (via accumulation of oncogenic homozygous mutations) and indirectly (via increased susceptibility to oncogenic pathogens) impact abnormal cell emergence and escape of immune surveillance. The observed link between reduced genetic diversity and cancer in wildlife may further imperil the long-term survival of numerous endangered species, highlighting the need to consider the impact of cancer in conservation biology. Finally, the somewhat incongruent data originating from human studies suggest that the association between genetic diversity and cancer development is multifactorial and may be tumour specific. Further studies are therefore crucial in order to elucidate the underpinnings of the interactions between genetic diversity, inbreeding and cancer.
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Affiliation(s)
- Beata Ujvari
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Waurn Ponds, Victoria 3216, Australia.,School of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, Tasmania 7001, Australia
| | - Marcel Klaassen
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Waurn Ponds, Victoria 3216, Australia
| | - Nynke Raven
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Waurn Ponds, Victoria 3216, Australia
| | - Tracey Russell
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Marion Vittecoq
- Institut de Recherche de la Tour du Valat, le Sambuc, 13200 Arles, France
| | - Rodrigo Hamede
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Waurn Ponds, Victoria 3216, Australia.,School of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, Tasmania 7001, Australia
| | - Frédéric Thomas
- CREEC/MIVEGEC, UMR IRD/CNRS/UM 5290, 911 Avenue Agropolis, BP 64501, 34394 Montpellier Cedex 5, France
| | - Thomas Madsen
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Waurn Ponds, Victoria 3216, Australia .,School of Biological Sciences, University of Wollongong, Wollongong, New South Wales 2522, Australia
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19
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Higa KC, DeGregori J. Decoy fitness peaks, tumor suppression, and aging. Aging Cell 2019; 18:e12938. [PMID: 30848555 PMCID: PMC6516171 DOI: 10.1111/acel.12938] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2019] [Accepted: 02/05/2019] [Indexed: 12/24/2022] Open
Abstract
Recent reports by Martincorena et al and Yokoyama et al reveal unanticipated dynamics of somatic evolution in the esophageal epithelium, with clonal expansions apparently driven by mutations in Notch1 dominating the epithelium even in middle-aged individuals, far outpacing the prevalence of these mutations in esophageal cancers. We propose a model whereby the promotion of clonal expansions by mutations such as in Notch1 can limit more malignant somatic evolutionary trajectories until old ages.
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Affiliation(s)
- Kelly C. Higa
- Department of Biochemistry and Molecular GeneticsUniversity of Colorado School of MedicineAuroraColorado
- Integrated Department of ImmunologyUniversity of Colorado School of MedicineAuroraColorado
| | - James DeGregori
- Department of Biochemistry and Molecular GeneticsUniversity of Colorado School of MedicineAuroraColorado
- Integrated Department of ImmunologyUniversity of Colorado School of MedicineAuroraColorado
- Department of PediatricsUniversity of Colorado School of MedicineAuroraColorado
- Department of Medicine, Section of HematologyUniversity of Colorado School of MedicineAuroraColorado
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20
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Rozhok A, DeGregori J. A generalized theory of age-dependent carcinogenesis. eLife 2019; 8:39950. [PMID: 31034356 PMCID: PMC6488293 DOI: 10.7554/elife.39950] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 04/08/2019] [Indexed: 12/22/2022] Open
Abstract
The Multi-Stage Model of Carcinogenesis (MMC), developed in the 1950 s-70s, postulated carcinogenesis as a Darwinian somatic selection process. The cellular organization of tissues was then poorly understood, with almost nothing known about cancer drivers and stem cells. The MMC paradigm was later confirmed, and cancer incidence was explained as a function of mutation occurrence. However, the MMC has never been tested for its ability to account for the discrepancies in the number of driver mutations and the organization of the stem cell compartments underlying different cancers that still demonstrate nearly universal age-dependent incidence patterns. Here we demonstrate by Monte Carlo modeling the impact of key somatic evolutionary parameters on the MMC performance, revealing that two additional major mechanisms, aging-dependent somatic selection and life history-dependent evolution of species-specific tumor suppressor mechanisms, need to be incorporated into the MMC to make it capable of generalizing cancer incidence across tissues and species. Editorial note This article has been through an editorial process in which the authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that all the issues have been addressed (see decision letter).
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Affiliation(s)
- Andrii Rozhok
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, United States
| | - James DeGregori
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, United States.,Department of Immunology and Microbiology, University of Colorado Anschutz Medical Campus, Aurora, United States.,Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, United States.,Department of Medicine, Section of Hematology, University of Colorado Anschutz Medical Campus, Aurora, United States
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21
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Harbour JW, Paez-Escamilla M, Cai L, Walter SD, Augsburger JJ, Correa ZM. Are Risk Factors for Growth of Choroidal Nevi Associated With Malignant Transformation? Assessment With a Validated Genomic Biomarker. Am J Ophthalmol 2019; 197:168-179. [PMID: 30195895 PMCID: PMC6291343 DOI: 10.1016/j.ajo.2018.08.045] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 08/23/2018] [Accepted: 08/23/2018] [Indexed: 12/21/2022]
Abstract
PURPOSE To test the hypothesis that widely used clinical risk factors for growth of choroidal nevi are associated with malignant transformation. METHODS Fine needle biopsy for assignment of gene expression profile (class 1 or class 2) was performed in 207 choroidal melanocytic tumors < 3.5 mm in thickness. The class 2 profile was employed as a validated biomarker for malignant transformation. The following data were collected: patient age and sex, tumor diameter and thickness, distance of posterior tumor margin from the optic disc, and the presence or absence of serous retinal detachment, orange lipofuscin pigment, drusen, retinal pigment epithelial fibrosis, retinal pigment epithelial atrophy, visual symptoms, and documented tumor growth. RESULTS Clinical features associated with the class 2 profile included patient age > 60 years and tumor thickness > 2.25 mm (Fisher exact test, P = .002 for both). Documented growth was not associated with the class 2 profile (P = .5). The odds ratio of a tumor having the class 2 profile was 2.8 (95% confidence interval 1.3-5.9) for patient age > 60 years and 3.5 (95% confidence interval 1.4-8.8) for tumor thickness > 2.25 mm. For patients with both risk factors, the "number needed to treat" to identify 1 patient with a class 2 tumor was 4.3 (P = .0002). No other clinical feature or combination of features was associated with the class 2 profile. CONCLUSIONS None of the widely used choroidal nevus risk factors for tumor growth, nor documented growth itself, is pathognomonic of malignant transformation as defined by class 2 gene expression profile. Patient age and tumor thickness may be helpful for identifying small choroidal melanocytic tumors that are more likely to have the class 2 profile. Observation for growth prior to treatment continues to be reasonable for most patients with suspicious choroidal nevi. NOTE: Publication of this article is sponsored by the American Ophthalmological Society.
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Affiliation(s)
- J William Harbour
- Ocular Oncology Service, Bascom Palmer Eye Institute and Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, Florida, USA.
| | - Manuel Paez-Escamilla
- Ocular Oncology Service, Bascom Palmer Eye Institute and Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Louis Cai
- Ocular Oncology Service, Bascom Palmer Eye Institute and Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Scott D Walter
- Ocular Oncology Service, Bascom Palmer Eye Institute and Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - James J Augsburger
- Department of Ophthalmology, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | - Zelia M Correa
- Wilmer Eye Institute, Johns Hopkins University, Baltimore, Maryland, USA
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22
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Doss M. Are We Approaching the End of the Linear No-Threshold Era? J Nucl Med 2018; 59:1786-1793. [PMID: 30262515 DOI: 10.2967/jnumed.118.217182] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Accepted: 09/24/2018] [Indexed: 12/12/2022] Open
Abstract
The linear no-threshold (LNT) model for radiation-induced cancer was adopted by national and international advisory bodies in the 1950s and has guided radiation protection policies worldwide since then. The resulting strict regulations have increased the compliance costs for the various uses of radiation, including nuclear medicine. The concerns about low levels of radiation due to the absence of a threshold have also resulted in adverse consequences. Justification of the LNT model was based on the concept that low levels of radiation increase mutations and that increased mutations imply increased cancers. This concept may not be valid. Low-dose radiation boosts defenses such as antioxidants and DNA repair enzymes. The boosted defenses would reduce the endogenous DNA damage that would have occurred in the subsequent period, and so the result would be reduced DNA damage and mutations. Whereas mutations are necessary for causing cancer, they are not sufficient since the immune system eliminates cancer cells or keeps them under control. The immune system plays an extremely important role in preventing cancer, as indicated by the substantially increased cancer risk in immune-suppressed patients. Hence, since low-dose radiation enhances the immune system, it would reduce cancers, resulting in a phenomenon known as radiation hormesis. There is considerable evidence for radiation hormesis and against the LNT model, including studies of atomic bomb survivors, background radiation, environmental radiation, cancer patients, medical radiation, and occupational exposures. Though Commentary 27 published by the National Council on Radiation Protection and Measurements concluded that recent epidemiologic studies broadly support the LNT model, a critical examination of the studies has shown that they do not. Another deficiency of Commentary 27 is that it did not consider the vast available evidence for radiation hormesis. Other advisory body reports that have supported the LNT model have similar deficiencies. Advisory bodies are urged to critically evaluate the evidence supporting both sides and arrive at an objective conclusion on the validity of the LNT model. Considering the strength of the evidence against the LNT model and the weakness of the evidence for it, the present analysis indicates that advisory bodies would be compelled to reject the LNT model. Hence, we may be approaching the end of the LNT model era.
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Affiliation(s)
- Mohan Doss
- Diagnostic Imaging, Fox Chase Cancer Center, Philadelphia, Pennsylvania
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23
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A matched cohort study of radio-chemotherapy versus radiotherapy alone in soft tissue sarcoma patients. Radiol Med 2018; 124:301-308. [PMID: 30209796 DOI: 10.1007/s11547-018-0939-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Accepted: 08/29/2018] [Indexed: 12/23/2022]
Abstract
PURPOSE Adjuvant radiotherapy is the standard postoperative treatment after conservative surgery in high risk soft tissue sarcoma. The role of adjuvant chemotherapy is still debated. Therefore, a matched cohort analysis was performed in high risk soft tissue patients to analyse differences in terms of clinical outcome and toxicity between patients treated with concomitant radio-chemotherapy (RTCT) and radiotherapy (RT) alone. MATERIALS AND METHODS For each patient in RT group was selected a patient in the RTCT group matching for age, T stage and grading. Acute and late toxicity were recorded, overall survival, recurrence free survival and distant metastases free survival were analysed and compared between the two groups. RESULTS Ninety patients were selected, half of patients underwent radio-chemotherapy and half received radiotherapy alone. During the treatment Grade 3 dermatitis was recorded in 15 (16.7%) patients, 6 (6.7%) patients associated chemotherapy and during follow up 12 (13.3%) patients developed grade 2 late fibrosis, 3 (3.3%) joint stiffness and 1 (1.1%) patient experienced a bone fracture. There were no differences in the rate of acute and late toxicity between RTCT and RT alone group. Nineteen (21.1%) patients developed local recurrence, overall 5-year local relapse free survival was 83%. There were no differences between the two groups. 29 patients developed distant metastases, 14 (15.6%) patients in the RTCT group and 15 (16.7%) patients in the RT group. The 5-year distant metastases free survival was 67%. Age > 65 years was the only independent factor affecting distant recurrence (HR = 5.7, 95% CI 2.7-11.9; p = 0.001). At the time of analysis 15 (16.7%) patients were dead, 6 (6.7%) patients in the RTCT group and 9 (10%) patients in the RT group. 5-years overall survival was: 88%. At multivariate analysis age > 65 years was an independent prognostic factor of overall survival (HR = 3.7, 95% CI 1.2-12.1, p = 0.037). CONCLUSIONS Prospective randomized studies with large size population and with subgroup analysis for histological subtypes are necessary to clarify the role of adjuvant chemotherapy in soft tissue sarcoma patients. Tailored treatment has to be considered in elderly soft tissue patients to guarantee a better outcome in this high risk and fragile population.
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24
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Candon D. The effect of cancer on the labor supply of employed men over the age of 65. ECONOMICS AND HUMAN BIOLOGY 2018; 31:184-199. [PMID: 30292988 DOI: 10.1016/j.ehb.2018.08.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Revised: 07/21/2018] [Accepted: 08/24/2018] [Indexed: 06/08/2023]
Abstract
This paper investigates the relationship between cancer diagnosis and the labor supply of employed men over the age of 65. While almost 60% of male cancers are diagnosed in men over the age of 65, no previous research has examined the effect that cancer has on this age group, which is surprising given the relevance of this group to public policy. With data from the Health and Retirement Study, I show that cancer has a significant negative effect on the labor supply of these workers. Using a combination of linear regression models and propensity score matching, I find that respondents who are diagnosed with cancer work 3 fewer hours per week than their non-cancer counterparts. They are also 10 percentage points more likely to stop working. This reduction seems to be driven by a deterioration in physical and mental health.
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Affiliation(s)
- David Candon
- School of Economics, University of Edinburgh, 30 Buccleuch Place, Edinburgh EH8 9JT, UK.
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25
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Abstract
Any therapy that aims at eradicating a cancerous growth will have at its core a cell death-inducing component. Here we argue that paediatric oncology presents with its unique set of considerations and problems, which—while taking the lead from oncological research experiences obtained from the adult population—need to be clinically evaluated independently. This is particularly true when considering long-term side effects. Precision medicine offers a promising new approach in therapy, but given as a monotherapy and in a limited combination, as found in an apoptosis inducer/sensitiser combination, it will most likely lead to mutation escape of the target cell population and the emergence of resistance. However, using the increasing amount of the molecular data as the basis for a complex combination therapy combining several key components such as cell death-inducing agents, kinase inhibitors and BH3 mimetics, holds great promise.
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26
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Cooper JN, Young NS. Clonality in context: hematopoietic clones in their marrow environment. Blood 2017; 130:2363-2372. [PMID: 29046282 PMCID: PMC5709788 DOI: 10.1182/blood-2017-07-794362] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 10/04/2017] [Indexed: 11/20/2022] Open
Abstract
Clonal hematopoiesis occurs normally, especially with aging, and in the setting of disease, not only in myeloid cancers but in bone marrow failure as well. In cancer, malignant clones are characterized by recurrent somatic mutations in specific sets of genes, but the direct relationship of such mutations to leukemogenesis, when they occur in cells of an apparently healthy older individual or after recovery from immune aplastic anemia, is uncertain. Here we emphasize a view of clonal evolution that stresses natural selection over deterministic ontogeny, and we stress the selective role of the environment of the marrow and organism. Clonal hematopoieses after chemotherapy, in marrow failure, and with aging serve as models. We caution against the overinterpretation of clinical results of genomic testing in the absence of a better understanding of clonal selection and evolution.
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Affiliation(s)
- James N Cooper
- Hematology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
| | - Neal S Young
- Hematology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
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27
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Bertolaso M, Dieli AM. Cancer and intercellular cooperation. ROYAL SOCIETY OPEN SCIENCE 2017; 4:170470. [PMID: 29134064 PMCID: PMC5666247 DOI: 10.1098/rsos.170470] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Accepted: 09/05/2017] [Indexed: 06/07/2023]
Abstract
The major transitions approach in evolutionary biology has shown that the intercellular cooperation that characterizes multicellular organisms would never have emerged without some kind of multilevel selection. Relying on this view, the Evolutionary Somatic view of cancer considers cancer as a breakdown of intercellular cooperation and as a loss of the balance between selection processes that take place at different levels of organization (particularly single cell and individual organism). This seems an elegant unifying framework for healthy organism, carcinogenesis, tumour proliferation, metastasis and other phenomena such as ageing. However, the gene-centric version of Darwinian evolution, which is often adopted in cancer research, runs into empirical problems: proto-tumoural and tumoural features in precancerous cells that would undergo 'natural selection' have proved hard to demonstrate; cells are radically context-dependent, and some stages of cancer are poorly related to genetic change. Recent perspectives propose that breakdown of intercellular cooperation could depend on 'fields' and other higher-level phenomena, and could be even mutations independent. Indeed, the field would be the context, allowing (or preventing) genetic mutations to undergo an intra-organism process analogous to natural selection. The complexities surrounding somatic evolution call for integration between multiple incomplete frameworks for interpreting intercellular cooperation and its pathologies.
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Affiliation(s)
- Marta Bertolaso
- Departmental Faculty of Engineering and FAST Institute for Philosophy of Scientific and Technological Practice, Università Campus Bio-Medico di Roma, Roma, Italy
| | - Anna Maria Dieli
- Department of Literature, Philosophy, and the Arts, University of Rome Tor Vergata, Roma, Italy
- Institute for the History and Philosophy of Science and Technology (IHPST), Paris 1 Panthéon-Sorbonne University, Paris, France
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28
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Matsuda Y, Seki A, Nonaka K, Kakizaki M, Wang T, Aida J, Ishikawa N, Nakano Y, Kaneda D, Takata T, Takahashi-Fujigasaki J, Murayama S, Takubo K, Ishiwata T, Sawabe M, Arai T. Clinicopathological characteristics of distant metastases of adenocarcinoma, squamous cell carcinoma and urothelial carcinoma: An autopsy study of older Japanese patients. Geriatr Gerontol Int 2017; 18:211-215. [DOI: 10.1111/ggi.13165] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Revised: 07/09/2017] [Accepted: 07/17/2017] [Indexed: 01/06/2023]
Affiliation(s)
- Yoko Matsuda
- Department of Pathology; Tokyo Metropolitan Geriatric Hospital; Tokyo Japan
| | - Atsuko Seki
- Department of Pathology; Tokyo Metropolitan Geriatric Hospital; Tokyo Japan
| | - Keisuke Nonaka
- Department of Pathology; Tokyo Metropolitan Geriatric Hospital; Tokyo Japan
| | - Mototsune Kakizaki
- Department of Pathology; Tokyo Metropolitan Geriatric Hospital; Tokyo Japan
| | - Tan Wang
- Department of Pathology; Tokyo Metropolitan Geriatric Hospital; Tokyo Japan
| | - Junko Aida
- Research Team for Geriatric Pathology; Tokyo Metropolitan Institute of Gerontology; Tokyo Japan
| | - Naoshi Ishikawa
- Research Team for Geriatric Pathology; Tokyo Metropolitan Institute of Gerontology; Tokyo Japan
| | - Yuta Nakano
- Department of Neuropathology (Brain Bank for Aging Research); Tokyo Metropolitan Institute of Gerontology; Tokyo Japan
| | - Daita Kaneda
- Department of Neuropathology (Brain Bank for Aging Research); Tokyo Metropolitan Institute of Gerontology; Tokyo Japan
| | - Tadayuki Takata
- Department of Neuropathology (Brain Bank for Aging Research); Tokyo Metropolitan Institute of Gerontology; Tokyo Japan
| | - Junko Takahashi-Fujigasaki
- Department of Neuropathology (Brain Bank for Aging Research); Tokyo Metropolitan Institute of Gerontology; Tokyo Japan
| | - Shigeo Murayama
- Department of Neuropathology (Brain Bank for Aging Research); Tokyo Metropolitan Institute of Gerontology; Tokyo Japan
| | - Kaiyo Takubo
- Research Team for Geriatric Pathology; Tokyo Metropolitan Institute of Gerontology; Tokyo Japan
| | - Toshiyuki Ishiwata
- Research Team for Geriatric Pathology; Tokyo Metropolitan Institute of Gerontology; Tokyo Japan
| | - Motoji Sawabe
- Graduate School of Health Care Sciences; Tokyo Medical and Dental University; Tokyo Japan
| | - Tomio Arai
- Department of Pathology; Tokyo Metropolitan Geriatric Hospital; Tokyo Japan
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29
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Chung JF, Lee SJ, Sood AK. Immunological consequences of ageing microvascular hemodynamic changes in view of cancer development and treatment. Oncotarget 2017; 8:69047-69061. [PMID: 28978180 PMCID: PMC5620320 DOI: 10.18632/oncotarget.17749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Accepted: 04/24/2017] [Indexed: 11/25/2022] Open
Abstract
Risk factors of cardiovascular diseases have long been implicated as risk factors for carcinogenesis, but clear explanations for their association have not been presented. In this article, fundamental concepts from carcinogenesis, microvascular hemodynamics, and immunity are collectively reviewed and analyzed in context of the known features of vascular ageing effects, in formulating a theory that suggests reduced microvascular immunity as an important driving factor for carcinogenesis. Furthermore, scientific, preclinical, and clinical evidence that support this new theory are presented in an interdisciplinary manner, offering new explanations to previously unanswered factors that impact cancer risks and its treatment outcome such as chronic drug use, temperature, stress and exercise effects among others. Forward-looking topics discussing the implications of this new idea to cancer immunotherapeutics are also discussed.
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Affiliation(s)
| | - Sang Joon Lee
- Division of Integrative Biosciences and Biotechnology (IBB), Pohang University of Science and Technology (POSTECH), Pohang, South Korea.,Center for Biofluid and Biomimic Research, Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, South Korea
| | - Anil K Sood
- Departments of Gynecologic Oncology and Reproductive Medicine and Cancer Biology, The University of Texas, MD Anderson Cancer Center, Houston, TX, USA.,Center for RNA Interference and Non-Coding RNAs, The University of Texas, MD Anderson Cancer Center, Houston, TX, USA
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30
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Mori H, Chen JQ, Cardiff RD, Pénzváltó Z, Hubbard NE, Schuetter L, Hovey RC, Trott JF, Borowsky AD. Pathobiology of the 129:Stat1 -/- mouse model of human age-related ER-positive breast cancer with an immune infiltrate-excluded phenotype. Breast Cancer Res 2017; 19:102. [PMID: 28865492 PMCID: PMC5581425 DOI: 10.1186/s13058-017-0892-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Accepted: 08/07/2017] [Indexed: 01/05/2023] Open
Abstract
Background Stat1 gene-targeted knockout mice (129S6/SvEvTac-Stat1tm1Rds) develop estrogen receptor-positive (ER+), luminal-type mammary carcinomas at an advanced age. There is evidence for both host environment as well as tumor cell-intrinsic mechanisms to initiate tumorigenesis in this model. In this report, we summarize details of the systemic and mammary pathology at preneoplastic and tumor-bearing time points. In addition, we investigate tumor progression in the 129:Stat1−/− host compared with wild-type 129/SvEv, and we describe the immune cell reaction to the tumors. Methods Mice housed and treated according to National Institutes of Health guidelines and Institutional Animal Care and Use Committee-approved methods were evaluated by histopathology, and their tissues were subjected to immunohistochemistry with computer-assisted quantitative image analysis. Tumor cell culture and conditioned media from cell culture were used to perform macrophage (RAW264.7) cell migration assays, including the 129:Stat1−/−-derived SSM2 cells as well as control Met1 and NDL tumor cells and EpH4 normal cells. Results Tumorigenesis in 129:Stat1−/− originates from a population of FoxA1+ large oval pale cells that initially appear and accumulate along the mammary ducts in segments or regions of the gland prior to giving rise to mammary intraepithelial neoplasias. Progression to invasive carcinoma is accompanied by a marked local stromal and immune cell response composed predominantly of T cells and macrophages. In conditioned media experiments, cells derived from 129:Stat1−/− tumors secrete both chemoattractant and chemoinhibitory factors, with greater attraction in the extracellular vesicular fraction and inhibition in the soluble fraction. The result appears to be recruitment of the immune reaction to the periphery of the tumor, with exclusion of immune cell infiltration into the tumor. Conclusions 129:Stat1−/− is a unique model for studying the critical origins and risk reduction strategies in age-related ER+ breast cancer. In addition, it can be used in preclinical trials of hormonal and targeted therapies as well as immunotherapies. Electronic supplementary material The online version of this article (doi:10.1186/s13058-017-0892-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Hidetoshi Mori
- Center for Comparative Medicine, University of California at Davis, Davis, CA, USA
| | - Jane Q Chen
- Center for Comparative Medicine, University of California at Davis, Davis, CA, USA
| | - Robert D Cardiff
- Center for Comparative Medicine, University of California at Davis, Davis, CA, USA.,Department of Pathology and Laboratory Medicine, School of Medicine, University of California at Davis, Sacramento, CA, USA
| | - Zsófia Pénzváltó
- Center for Comparative Medicine, University of California at Davis, Davis, CA, USA
| | - Neil E Hubbard
- Center for Comparative Medicine, University of California at Davis, Davis, CA, USA
| | - Louis Schuetter
- Center for Comparative Medicine, University of California at Davis, Davis, CA, USA
| | - Russell C Hovey
- Department of Animal Science, University of California at Davis, Davis, CA, USA
| | - Josephine F Trott
- Department of Animal Science, University of California at Davis, Davis, CA, USA
| | - Alexander D Borowsky
- Center for Comparative Medicine, University of California at Davis, Davis, CA, USA. .,Department of Pathology and Laboratory Medicine, School of Medicine, University of California at Davis, Sacramento, CA, USA.
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31
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DeGregori J. Connecting Cancer to Its Causes Requires Incorporation of Effects on Tissue Microenvironments. Cancer Res 2017; 77:6065-6068. [PMID: 28754675 DOI: 10.1158/0008-5472.can-17-1207] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Revised: 05/29/2017] [Accepted: 07/13/2017] [Indexed: 11/16/2022]
Abstract
In a recent article in Science, Tomasetti and colleagues present an expanded model for cancer risk, which they claim demonstrates the relative contribution of mutations caused by replication errors, environment, and heredity. The foundation of this model is the theory that the overwhelming driver of cancer risk is mutations. This perspective will present experimental evidence and evolutionary theory to challenge the basis of this underlying theory. An argument will be presented that the mutation-centric model of cancer suggests unrealistic solutions to cancer and distracts the research community from more promising approaches that consider tissue context. Cancer Res; 77(22); 6065-8. ©2017 AACR.
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Affiliation(s)
- James DeGregori
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, Colorado.
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32
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Scott J, Marusyk A. Somatic clonal evolution: A selection-centric perspective. Biochim Biophys Acta Rev Cancer 2017; 1867:139-150. [DOI: 10.1016/j.bbcan.2017.01.006] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 01/29/2017] [Accepted: 01/30/2017] [Indexed: 12/31/2022]
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Kwok CL, Lee CK, Lo WT, Yip PS. The Contribution of Ageing to Hospitalisation Days in Hong Kong: A Decomposition Analysis. Int J Health Policy Manag 2017; 6:155-164. [PMID: 28812795 PMCID: PMC5337253 DOI: 10.15171/ijhpm.2016.108] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 08/06/2016] [Indexed: 01/22/2023] Open
Abstract
Background: Ageing has become a serious challenge in Hong Kong and globally. It has serious implications for health expenditure, which accounts for nearly 20% of overall government expenditure. Here we assess the contribution of ageing and related factors to hospitalisation days in Hong Kong. We used hospital discharge data from all publicly funded hospitals in Hong Kong between 2001 and 2012.
Methods: A decomposition method was used to examine the factors that account for the change of total hospitalisation days during the two periods, 2001-2004 and 2004-2012. The five factors include two demographic factors – population size and age-gender composition – and three service components – hospital discharge rate, number of discharge episodes per patient, and average length of stay (LOS) – which are all measured at age-gender group level. In order to assess the health cost burden in the future, we also project the total hospitalisation days up to 2041, for a range of scenarios.
Results: During the decreasing period of hospitalisation days (2001-2004), the reduction of LOS contributed to about 60% of the reduction. For the period of increase (2004-2012), ageing is associated with an increase in total hospitalisation days of 1.03 million, followed by an increase in hospital discharge rates (0.67 million), an increase in the number of discharge episodes per patient (0.62 million), and population growth (0.43 million). The reduction of LOS has greatly offset these increases (-2.19 million days), and has become one of the most significant factors in containing the increasing number of hospitalisation days. Projected increases in total hospitalisation days under different scenarios have highlighted that the contribution of ageing will become even more prominent after 2022.
Conclusion: Hong Kong is facing increasing healthcare burden caused by the rapid increase in demand for inpatient services due to ageing. Better management of inpatient services with the aim of increasing efficiency and reducing LOS, avoidable hospitalisation and readmission, without compromising patient satisfaction and quality of service, are crucial for containing the rapid and enormous increases in total hospitalisation days for Hong Kong. The results would be relevant to many rapidly ageing societies in this region.
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Affiliation(s)
- Chi Leung Kwok
- HKJC Centre for Suicide Research and Prevention, The University of Hong Kong, Pokfulam, Hong Kong
| | - Carmen Km Lee
- Department of Social Work and Social Administration, The University of Hong Kong, Pokfulam, Hong Kong
| | - William Tl Lo
- Kwai Chung Hospital, Hospital Authority, Kwai Chung, Hong Kong
| | - Paul Sf Yip
- HKJC Centre for Suicide Research and Prevention, The University of Hong Kong, Pokfulam, Hong Kong.,Department of Social Work and Social Administration, The University of Hong Kong, Pokfulam, Hong Kong
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34
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Liggett LA, DeGregori J. Changing mutational and adaptive landscapes and the genesis of cancer. Biochim Biophys Acta Rev Cancer 2017; 1867:84-94. [PMID: 28167050 DOI: 10.1016/j.bbcan.2017.01.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2016] [Revised: 01/27/2017] [Accepted: 01/28/2017] [Indexed: 12/31/2022]
Abstract
By the time the process of oncogenesis has produced an advanced cancer, tumor cells have undergone extensive evolution. The cellular phenotypes resulting from this evolution have been well studied, and include accelerated growth rates, apoptosis resistance, immortality, invasiveness, and immune evasion. Yet with all of our current knowledge of tumor biology, the details of early oncogenesis have been difficult to observe and understand. Where different oncogenic mutations may work together to enhance the survival of a tumor cell, in isolation they are often pro-apoptotic, pro-differentiative or pro-senescent, and therefore often, somewhat paradoxically, disadvantageous to a cell. It is also becoming clear that somatic mutations, including those in known oncogenic drivers, are common in tissues starting at a young age. These observations raise the question: how do we largely avoid cancer for most of our lives? Here we propose that evolutionary forces can help explain this paradox. As humans and other organisms age or experience external insults such as radiation or smoking, the structure and function of tissues progressively degrade, resulting in altered stem cell niche microenvironments. As tissue integrity declines, it becomes less capable of supporting and maintaining resident stem cells. These stem cells then find themselves in a microenvironment to which they are poorly adapted, providing a competitive advantage to those cells that can restore their functionality and fitness through mutations or epigenetic changes. The resulting oncogenic clonal expansions then increase the odds of further cancer progression. Understanding how the causes of cancer, such as aging or smoking, affect tissue microenvironments to control the impact of mutations on somatic cell fitness can help reconcile the discrepancy between marked mutation accumulation starting early in life and the somatic evolution that leads to cancer at advanced ages or following carcinogenic insults. This article is part of a Special Issue entitled: Evolutionary principles - heterogeneity in cancer?, edited by Dr. Robert A. Gatenby.
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Affiliation(s)
- L Alexander Liggett
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, United States
| | - James DeGregori
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, United States; Integrated Department of Immunology, University of Colorado School of Medicine, Aurora, CO 80045, United States; Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045, United States; Department of Medicine, Section of Hematology, University of Colorado School of Medicine, Aurora, CO 80045, United States.
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35
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Hochberg ME, Noble RJ. A framework for how environment contributes to cancer risk. Ecol Lett 2017; 20:117-134. [DOI: 10.1111/ele.12726] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2016] [Revised: 10/03/2016] [Accepted: 12/01/2016] [Indexed: 12/22/2022]
Affiliation(s)
- Michael E. Hochberg
- Intstitut des Sciences de l'Evolution de Montpellier; Université de Montpellier; Place E. Bataillon, CC065 34095 Montpellier Cedex 5 France
- Santa Fe Institute; 1399 Hyde Park Rd. Santa Fe NM 87501 USA
| | - Robert J. Noble
- Intstitut des Sciences de l'Evolution de Montpellier; Université de Montpellier; Place E. Bataillon, CC065 34095 Montpellier Cedex 5 France
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36
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Lideikaitė A, Mozūraitienė J, Letautienė S. Analysis of prognostic factors for melanoma patients. Acta Med Litu 2017; 24:25-34. [PMID: 28630590 PMCID: PMC5467960 DOI: 10.6001/actamedica.v24i1.3460] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 03/14/2017] [Indexed: 11/27/2022] Open
Abstract
Introduction. Melanoma is the most dangerous form of skin cancer. Morbidity from melanoma is increasing every year. Previous studies have revealed that there are some demographic and clinical factors having effect on melanoma survival prognosis. Aim of the study. Purpose of our study was to assess melanoma survival depending on prognostic factors, such as age, sex, stage, depth, histology and anatomical site. Materials and methods. We investigated melanoma-specific survival up to 10 years in 85 primary cases of melanoma from diagnosis at the National Cancer Institute in 2006. Analysis was performed for one-, five-, and ten-year survival. The data were processed with Microsoft Excel, data analysis was conducted using SPSS® software. Results. Melanomas diagnosed at stage IV or thicker than 4.00 mm had lower survival (five-year survival: 12.5% and 26.66%, respectively). A significant survival difference was observed among the different stages (p = 0.003) and different depths (p = 0.049) of melanoma. Ten-year survival was 32% for men and 61% for women, but melanoma-specific survival dependent on sex did not have a statistically significant difference (p = 0.121). In persons diagnosed at the age of 65 or older, ten-year survival was lower than in those of 40-64 years of age and in the age group of 15-39 years (44.44% and 26.66%, respectively), but melanoma-specific survival in different age groups did not have a statistically significant difference (p = 0.455). Back/breast skin melanoma had lower ten-year survival (37.03%) than other anatomic sites. Nodular melanoma had the poorest five-year and ten-year melanoma-specific survival among histological subtypes (51.67% and 38.75%). The differences between melanoma localizations (p = 0.457) and histological types (p = 0.364) were not statistically significant. Conclusions. Lower melanoma-specific survival rates were observed among patients diagnosed at a late stage, older age, and when melanomas were thicker than 4.00 mm. Female and younger patients had better melanoma-specific survival than men and older people, and these differences were statistically significant. Melanoma diagnosed at an early stage and of a small depth had higher survival rates. Back/breast skin melanoma had poorer prognosis than other anatomic sites. Nodular melanoma had the lowest melanoma-specific survival, while superficial spreading or lentigo maligna had the best prognosis among histological subtypes. However, differences in melanoma survival in different sex and age groups, localizations and histological types were not statistically significant.
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Affiliation(s)
| | | | - Simona Letautienė
- Faculty of Medicine, Vilnius University
- National Cancer Institute, Vilnius, Lithuania
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37
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Sippey M, Spaniolas K, Kasten KR. Elucidating Trainee Effect on Outcomes for General, Gynecologic, and Urologic Oncology Procedures. J INVEST SURG 2016; 30:359-367. [PMID: 27929699 DOI: 10.1080/08941939.2016.1255805] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BACKGROUND AND OBJECTIVES Surgical complications delay adjuvant therapy in oncology patients. Current literature remains unclear regarding resident effect on postoperative outcomes, with inappropriate coverage possibly endangering patients in spite of attending oversight. We assessed resident postgraduate year (PGY) effect on 30-day overall morbidity in cancer patients undergoing major intra-abdominal and non-abdominal surgery. METHODS Patients undergoing non-emergent major intra- and extra-abdominal operations from 2005-2012 were queried using the American College of Surgeons' National Surgical Quality Improvement Program. Attending alone and resident PGY cohorts were compared for demographics, 30-day overall morbidity, mortality, and relevant outcomes. RESULTS A total of 156,941 cancer patients undergoing major intra-abdominal (n = 76,385) or major non-abdominal (n = 80,556) procedures were captured. Demographics were clinically similar across attending and PGY levels. Rates of overall morbidity increased significantly with PGY level, along with operative time and length of stay. For major intra-abdominal procedures, all resident levels except PGY2 level adversely affected overall morbidity. Above PGY4 level, resident involvement had a stronger association with adverse outcome than preoperative comorbidities and preoperative chemotherapy. Interestingly, gastric, gall bladder, liver, pancreas, esophageal, and thyroid procedures demonstrated no effect of resident involvement on overall morbidity. CONCLUSIONS Resident PGY is independently associated with increased overall morbidity in patients undergoing selected major surgical procedures. Understanding surgical procedures affected by resident involvement will maximize outcomes.
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Affiliation(s)
- Megan Sippey
- a Department of Surgery , Brody School of Medicine at East Carolina University , Greenville , North Carolina , USA
| | - Konstantinos Spaniolas
- a Department of Surgery , Brody School of Medicine at East Carolina University , Greenville , North Carolina , USA
| | - Kevin R Kasten
- b Department of Surgery , Carolinas Health Care System , Charlotte , North Carolina , USA
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Abstract
The war on cancer has been fought during the past several decades primarily based on the somatic mutation model of cancer. This has resulted in the emphasis on cancer screening and elimination of any detected cancerous/precancerous cells as the primary method of cancer prevention. This approach has reduced mortality from some cancers, but age-adjusted cancer mortality rates continue to be high. The lack of significant progress in reducing cancer mortality rates may be indicative of a fundamental flaw in the cancer model used. An alternative model of cancer is the immune suppression model of cancer based on the tremendous increase in cancers when the immune system is suppressed. According to this model, the key carcinogenic event is the suppression of the immune system which enables the already existing covert cancers to grow uncontrollably, causing cancer. Hence, cancer screening would consist of identifying those with weak immune system response. The primary mode of cancer prevention and treatment would be boosting of the immune system, for example, through exercise, infection, and low-dose radiation, as they are all known to enhance immune system response and reduce cancers. There is sufficient evidence to justify clinical trials of this approach for cancer screening, prevention, and treatment.
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Affiliation(s)
- Mohan Doss
- Diagnostic Imaging, Fox Chase Cancer Center, Philadelphia, PA, USA
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39
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Abstract
The Armitage-Doll multi-stage model of carcinogenesis tremendously refocused cancer science by postulating that carcinogenesis is driven by a sequence of genetic changes in cells. Age-dependent cancer incidence thus has been explained in terms of the time necessary for oncogenic mutations to occur. While the multi-step nature of cancer evolution is well-supported by evidence, the mutation-centric theory is unable to explain a number of phenomena, such as the disproportion between cancer frequency and animal body size or the scaling of cancer incidence to animal lifespan. In this paper, we present a theoretical review of the current paradigm and discuss some fundamental evolutionary theory postulates that explain why cancer incidence is a function of lifespan and physiological, not chronological, aging.
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Affiliation(s)
- Andrii I. Rozhok
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045
| | - James DeGregori
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045
- Integrated Department of Immunology, University of Colorado School of Medicine, Aurora, CO 80045
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045
- Department of Medicine, Section of Hematology, University of Colorado School of Medicine, Aurora, CO 80045
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40
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Abstract
Studies of body size evolution, and life-history theory in general, are conducted without taking into account cancer as a factor that can end an organism's reproductive lifespan. This reflects a tacit assumption that predation, parasitism and starvation are of overriding importance in the wild. We argue here that even if deaths directly attributable to cancer are a rarity in studies of natural populations, it remains incorrect to infer that cancer has not been of importance in shaping observed life histories. We present first steps towards a cancer-aware life-history theory, by quantifying the decrease in the length of the expected reproductively active lifespan that follows from an attempt to grow larger than conspecific competitors. If all else is equal, a larger organism is more likely to develop cancer, but, importantly, many factors are unlikely to be equal. Variations in extrinsic mortality as well as in the pace of life—larger organisms are often near the slow end of the fast–slow life-history continuum—can make realized cancer incidences more equal across species than what would be observed in the absence of adaptive responses to cancer risk (alleviating the so-called Peto's paradox). We also discuss reasons why patterns across species can differ from within-species predictions. Even if natural selection diminishes cancer susceptibility differences between species, within-species differences can remain. In many sexually dimorphic cases, we predict males to be more cancer-prone than females, forming an understudied component of sexual conflict.
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Affiliation(s)
- Hanna Kokko
- Wissenschaftskolleg zu Berlin, Institute for Advanced Study, Wallotstrasse 19, Berlin 14193, Germany Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, Zurich 8057, Switzerland
| | - Michael E Hochberg
- Wissenschaftskolleg zu Berlin, Institute for Advanced Study, Wallotstrasse 19, Berlin 14193, Germany Institut des Sciences de l'Evolution, Université Montpellier, UMR5554 du CNRS, Montpellier 34095, France Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, NM 87501, USA
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Variation in KRAS driver substitution distributions between tumor types is determined by both mutation and natural selection. Sci Rep 2016; 6:21927. [PMID: 26902163 PMCID: PMC4763303 DOI: 10.1038/srep21927] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Accepted: 02/02/2016] [Indexed: 02/06/2023] Open
Abstract
Different tumor types vary greatly in their distribution of driver substitutions. Here, we analyzed how mutation and natural selection contribute to differences in the distribution of KRAS driver substitutions between lung, colon and pancreatic adenocarcinomas. We were able to demonstrate that both differences in mutation and differences in selection drive variation in the distribution of KRAS driver substitutions between tumor types. By accounting for the effects of mutation on the distribution of KRAS driver substitutions, we could identify specific KRAS driver substitutions that are more favored by selection in specific tumor types. Such driver substitutions likely improve fitness most when they occur within the context of the tumor type in which they are preferentially favored. Fitting with this, we found that driver substitutions that are more favored by natural selection in a specific type of tumor tend to associate with worse clinical outcomes specifically in that type of tumor.
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Yadav VK, DeGregori J, De S. The landscape of somatic mutations in protein coding genes in apparently benign human tissues carries signatures of relaxed purifying selection. Nucleic Acids Res 2016; 44:2075-84. [PMID: 26883632 PMCID: PMC4797307 DOI: 10.1093/nar/gkw086] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Accepted: 01/31/2016] [Indexed: 11/23/2022] Open
Abstract
Mutations acquired during development and aging lead to inter- and intra-tissue genetic variations. Evidence linking such mutations to complex traits and diseases is rising. We detected somatic mutations in protein-coding regions in 140 benign tissue samples representing nine tissue-types (bladder, breast, liver, lung, prostate, stomach, thyroid, head and neck) and paired blood from 70 donors. A total of 80% of the samples had 2–39 mutations detectable at tissue-level resolution. Factors such as age and smoking were associated with increased burden of detectable mutations, and tissues carried signatures of distinct mutagenic processes such as oxidative DNA damage and transcription-coupled repair. Using mutational signatures, we predicted that majority of the mutations in blood originated in hematopoietic stem and early progenitor cells. Missense to silent mutations ratio and the persistence of potentially damaging mutations in expressed genes carried signatures of relaxed purifying selection. Our findings have relevance for etiology, diagnosis and treatment of diseases including cancer.
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Affiliation(s)
- Vinod Kumar Yadav
- Department of Medicine, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - James DeGregori
- Department of Biochemistry and Molecular Genetics. University of Colorado School of Medicine, Aurora, CO 80045, USA Molecular Oncology Program, University of Colorado Cancer Center, Aurora, CO 80045, USA
| | - Subhajyoti De
- Department of Medicine, University of Colorado School of Medicine, Aurora, CO 80045, USA Molecular Oncology Program, University of Colorado Cancer Center, Aurora, CO 80045, USA Department of Biostatistics and Informatics, Colorado School of Public Health, Aurora, CO 80045, USA
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43
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Fleenor CJ, Rozhok AI, Zaberezhnyy V, Mathew D, Kim J, Tan AC, Bernstein ID, DeGregori J. Contrasting roles for C/EBPα and Notch in irradiation-induced multipotent hematopoietic progenitor cell defects. Stem Cells 2016; 33:1345-58. [PMID: 25546133 DOI: 10.1002/stem.1936] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Revised: 11/14/2014] [Accepted: 11/21/2014] [Indexed: 12/17/2022]
Abstract
Ionizing radiation (IR) is associated with reduced hematopoietic function and increased risk of hematopoietic malignancies, although the mechanisms behind these relationships remain poorly understood. Both effects of IR have been commonly attributed to the direct induction of DNA mutations, but evidence supporting these hypotheses is largely lacking. Here we demonstrate that IR causes long-term, somatically heritable, cell-intrinsic reductions in hematopoietic stem cell (HSC) and multipotent hematopoietic progenitor cell (mHPC) self-renewal that are mediated by C/EBPα and reversed by Notch. mHPC from previously irradiated (>9 weeks prior), homeostatically restored mice exhibit gene expression profiles consistent with their precocious differentiation phenotype, including decreased expression of HSC-specific genes and increased expression of myeloid program genes (including C/EBPα). These gene expression changes are reversed by ligand-mediated activation of Notch. Loss of C/EBPα expression is selected for within previously irradiated HSC and mHPC pools and is associated with reversal of IR-dependent precocious differentiation and restoration of self-renewal. Remarkably, restoration of mHPC self-renewal by ligand-mediated activation of Notch prevents selection for C/EBPα loss of function in previously irradiated mHPC pools. We propose that environmental insults prompt HSC to initiate a program limiting their self-renewal, leading to loss of the damaged HSC from the pool while allowing this HSC to temporarily contribute to differentiated cell pools. This "programmed mediocrity" is advantageous for the sporadic genotoxic insults animals have evolved to deal with but becomes tumor promoting when the entire HSC compartment is damaged, such as during total body irradiation, by increasing selective pressure for adaptive oncogenic mutations.
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Henry CJ, Casás-Selves M, Kim J, Zaberezhnyy V, Aghili L, Daniel AE, Jimenez L, Azam T, McNamee EN, Clambey ET, Klawitter J, Serkova NJ, Tan AC, Dinarello CA, DeGregori J. Aging-associated inflammation promotes selection for adaptive oncogenic events in B cell progenitors. J Clin Invest 2015; 125:4666-80. [PMID: 26551682 DOI: 10.1172/jci83024] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 10/01/2015] [Indexed: 12/21/2022] Open
Abstract
The incidence of cancer is higher in the elderly; however, many of the underlying mechanisms for this association remain unexplored. Here, we have shown that B cell progenitors in old mice exhibit marked signaling, gene expression, and metabolic defects. Moreover, B cell progenitors that developed from hematopoietic stem cells (HSCs) transferred from young mice into aged animals exhibited similar fitness defects. We further demonstrated that ectopic expression of the oncogenes BCR-ABL, NRAS(V12), or Myc restored B cell progenitor fitness, leading to selection for oncogenically initiated cells and leukemogenesis specifically in the context of an aged hematopoietic system. Aging was associated with increased inflammation in the BM microenvironment, and induction of inflammation in young mice phenocopied aging-associated B lymphopoiesis. Conversely, a reduction of inflammation in aged mice via transgenic expression of α-1-antitrypsin or IL-37 preserved the function of B cell progenitors and prevented NRAS(V12)-mediated oncogenesis. We conclude that chronic inflammatory microenvironments in old age lead to reductions in the fitness of B cell progenitor populations. This reduced progenitor pool fitness engenders selection for cells harboring oncogenic mutations, in part due to their ability to correct aging-associated functional defects. Thus, modulation of inflammation--a common feature of aging--has the potential to limit aging-associated oncogenesis.
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Toward an evolutionary model of cancer: Considering the mechanisms that govern the fate of somatic mutations. Proc Natl Acad Sci U S A 2015. [PMID: 26195756 DOI: 10.1073/pnas.1501713112] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Our understanding of cancer has greatly advanced since Nordling [Nordling CO (1953) Br J Cancer 7(1):68-72] and Armitage and Doll [Armitage P, Doll R (1954) Br J Cancer 8(1):1-12] put forth the multistage model of carcinogenesis. However, a number of observations remain poorly understood from the standpoint of this paradigm in its contemporary state. These observations include the similar age-dependent exponential rise in incidence of cancers originating from stem/progenitor pools differing drastically in size, age-dependent cell division profiles, and compartmentalization. This common incidence pattern is characteristic of cancers requiring different numbers of oncogenic mutations, and it scales to very divergent life spans of mammalian species. Also, bigger mammals with larger underlying stem cell pools are not proportionally more prone to cancer, an observation known as Peto's paradox. Here, we present a number of factors beyond the occurrence of oncogenic mutations that are unaccounted for in the current model of cancer development but should have significant impacts on cancer incidence. Furthermore, we propose a revision of the current understanding for how oncogenic and other functional somatic mutations affect cellular fitness. We present evidence, substantiated by evolutionary theory, demonstrating that fitness is a dynamic environment-dependent property of a phenotype and that oncogenic mutations should have vastly different fitness effects on somatic cells dependent on the tissue microenvironment in an age-dependent manner. Combined, this evidence provides a firm basis for understanding the age-dependent incidence of cancers as driven by age-altered systemic processes regulated above the cell level.
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Fleenor CJ, Higa K, Weil MM, DeGregori J. Evolved Cellular Mechanisms to Respond to Genotoxic Insults: Implications for Radiation-Induced Hematologic Malignancies. Radiat Res 2015; 184:341-51. [PMID: 26414506 DOI: 10.1667/rr14147.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Human exposure to ionizing radiation is highly associated with adverse health effects, including reduced hematopoietic cell function and increased risk of carcinogenesis. The hematopoietic deficits manifest across blood cell types and persist for years after radiation exposure, suggesting a long-lived and multi-potent cellular reservoir for radiation-induced effects. As such, research has focused on identifying both the immediate and latent hematopoietic stem cell responses to radiation exposure. Radiation-associated effects on hematopoietic function and malignancy development have generally been attributed to the direct induction of mutations resulting from radiation-induced DNA damage. Other studies have illuminated the role of cellular programs that both limit and enhance radiation-induced tissue phenotypes and carcinogenesis. In this review, distinct but collaborative cellular responses to genotoxic insults are highlighted, with an emphasis on how these programmed responses impact hematopoietic cellular fitness and competition. These radiation-induced cellular programs include apoptosis, senescence and impaired self-renewal within the hematopoietic stem cell (HSC) pool. In the context of sporadic DNA damage to a cell, these cellular responses act in concert to restore tissue function and prevent selection for adaptive oncogenic mutations. But in the contexts of whole-tissue exposure or whole-body exposure to genotoxins, such as radiotherapy or chemotherapy, we propose that these programs can contribute to long-lasting tissue impairment and increased carcinogenesis.
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Affiliation(s)
| | | | - Michael M Weil
- d Department of Environmental and Radiological Health Sciences, Colorado State University; Fort Collins, Colorado
| | - James DeGregori
- Departments of a Immunology.,b Biochemistry and Molecular Genetics and.,c Medicine, School of Medicine, University of Colorado, Aurora, Colorado; and
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Burkhalter MD, Rudolph KL, Sperka T. Genome instability of ageing stem cells--Induction and defence mechanisms. Ageing Res Rev 2015; 23:29-36. [PMID: 25668152 PMCID: PMC4504031 DOI: 10.1016/j.arr.2015.01.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 01/28/2015] [Accepted: 01/30/2015] [Indexed: 01/25/2023]
Abstract
Stem cell function is declining with increasing age. DNA lesions and mutations accumulate in ageing stem cells. Inability to repair DNA can lead to premature depletion of stem cell pools. Checkpoint function preserves genomic integrity at young age. Enforced checkpoint induction contributes to stem cell ageing.
The mammalian organism is comprised of tissue types with varying degrees of self-renewal and regenerative capacity. In most organs self-renewing tissue-specific stem and progenitor cells contribute to organ maintenance, and it is vital to maintain a functional stem cell pool to preserve organ homeostasis. Various conditions like tissue injury, stress responses, and regeneration challenge the stem cell pool to re-establish homeostasis (Fig. 1). However, with increasing age the functionality of adult stem cells declines and genomic mutations accumulate. These defects affect different cellular response pathways and lead to impairments in regeneration, stress tolerance, and organ function as well as to an increased risk for the development of ageing associated diseases and cancer. Maintenance of the genome appears to be of utmost importance to preserve stem cell function and to reduce the risk of ageing associated dysfunctions and pathologies. In this review, we discuss the causal link between stem cell dysfunction and DNA damage accrual, different strategies how stem cells maintain genome integrity, and how these processes are affected during ageing.
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Rozhok AI, Salstrom JL, DeGregori J. Stochastic modeling indicates that aging and somatic evolution in the hematopoetic system are driven by non-cell-autonomous processes. Aging (Albany NY) 2015; 6:1033-48. [PMID: 25564763 PMCID: PMC4298364 DOI: 10.18632/aging.100707] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Age-dependent tissue decline and increased cancer incidence are widely accepted to be rate-limited by the accumulation of somatic mutations over time. Current models of carcinogenesis are dominated by the assumption that oncogenic mutations have defined advantageous fitness effects on recipient stem and progenitor cells, promoting and rate-limiting somatic evolution. However, this assumption is markedly discrepant with evolutionary theory, whereby fitness is a dynamic property of a phenotype imposed upon and widely modulated by environment. We computationally modeled dynamic microenvironment-dependent fitness alterations in hematopoietic stem cells (HSC) within the Sprengel-Liebig system known to govern evolution at the population level. Our model for the first time integrates real data on age-dependent dynamics of HSC division rates, pool size, and accumulation of genetic changes and demonstrates that somatic evolution is not rate-limited by the occurrence of mutations, but instead results from aged microenvironment-driven alterations in the selective/fitness value of previously accumulated genetic changes. Our results are also consistent with evolutionary models of aging and thus oppose both somatic mutation-centric paradigms of carcinogenesis and tissue functional decline. In total, we demonstrate that aging directly promotes HSC fitness decline and somatic evolution via non-cell-autonomous mechanisms.
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Affiliation(s)
- Andrii I Rozhok
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Jennifer L Salstrom
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA. Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - James DeGregori
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA. Integrated Department of Immunology, University of Colorado School of Medicine, Aurora, CO 80045, USA. Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045, USA. Department of Medicine, Section of Hematology, University of Colorado School of Medicine, Aurora, CO 80045,USA
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Noble R, Kaltz O, Hochberg ME. Peto's paradox and human cancers. Philos Trans R Soc Lond B Biol Sci 2015; 370:20150104. [PMID: 26056357 PMCID: PMC4581036 DOI: 10.1098/rstb.2015.0104] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/27/2015] [Indexed: 12/26/2022] Open
Abstract
Peto's paradox is the lack of the expected trend in cancer incidence as a function of body size and lifespan across species. The leading hypothesis to explain this pattern is natural selection for differential cancer prevention in larger, longer lived species. We evaluate whether a similar effect exists within species, specifically humans. We begin by reanalysing a recently published dataset to separate the effects of stem cell number and replication rate, and show that each has an independent effect on cancer risk. When considering the lifetime number of stem cell divisions in an extended dataset, and removing cases associated with other diseases or carcinogens, we find that lifetime cancer risk per tissue saturates at approximately 0.3-1.3% for the types considered. We further demonstrate that grouping by anatomical site explains most of the remaining variation. Our results indicate that cancer risk depends not only on the number of stem cell divisions but varies enormously (approx. 10 000 times) depending on anatomical site. We conclude that variation in risk of human cancer types is analogous to the paradoxical lack of variation in cancer incidence among animal species and may likewise be understood as a result of evolution by natural selection.
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Affiliation(s)
- Robert Noble
- Institut des Sciences de l'Evolution, Université de Montpellier, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France
| | - Oliver Kaltz
- Institut des Sciences de l'Evolution, Université de Montpellier, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France
| | - Michael E Hochberg
- Institut des Sciences de l'Evolution, Université de Montpellier, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, NM 87501, USA
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Rozhok AI, Wahl GM, DeGregori J. A Critical Examination of the "Bad Luck" Explanation of Cancer Risk. Cancer Prev Res (Phila) 2015; 8:762-4. [PMID: 26122457 DOI: 10.1158/1940-6207.capr-15-0229] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 06/05/2015] [Indexed: 02/01/2023]
Abstract
Tomasetti and Vogelstein (1) argue that lifetime cancer risk for particular tissues is mostly determined by the total number of stem cell (SC) divisions within the tissue, whereby most cancers arise due to "bad luck"—mutations occurring during DNA replication. We argue that the poorly substantiated estimations of SC division parameters and assumptions that oversimplify somatic evolution prevent such a conclusion from being drawn.
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Affiliation(s)
- Andrii I Rozhok
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, Colorado
| | - Geoffrey M Wahl
- Gene Expression Laboratory, The Salk Institute, La Jolla, CA
| | - James DeGregori
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, Colorado.
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