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Strobl MAR, West J, Viossat Y, Damaghi M, Robertson-Tessi M, Brown JS, Gatenby RA, Maini PK, Anderson ARA. Turnover Modulates the Need for a Cost of Resistance in Adaptive Therapy. Cancer Res 2021; 81:1135-1147. [PMID: 33172930 PMCID: PMC8455086 DOI: 10.1158/0008-5472.can-20-0806] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 08/06/2020] [Accepted: 11/06/2020] [Indexed: 11/16/2022]
Abstract
Adaptive therapy seeks to exploit intratumoral competition to avoid, or at least delay, the emergence of therapy resistance in cancer. Motivated by promising results in prostate cancer, there is growing interest in extending this approach to other neoplasms. As such, it is urgent to understand the characteristics of a cancer that determine whether or not it will respond well to adaptive therapy. A plausible candidate for such a selection criterion is the fitness cost of resistance. In this article, we study a general, but simple, mathematical model to investigate whether the presence of a cost is necessary for adaptive therapy to extend the time to progression beyond that of a standard-of-care continuous therapy. Tumor cells were divided into sensitive and resistant populations and we model their competition using a system of two ordinary differential equations based on the Lotka-Volterra model. For tumors close to their environmental carrying capacity, a cost was not required. However, for tumors growing far from carrying capacity, a cost may be required to see meaningful gains. Notably, it is important to consider cell turnover in the tumor, and we discuss its role in modulating the impact of a resistance cost. To conclude, we present evidence for the predicted cost-turnover interplay in data from 67 patients with prostate cancer undergoing intermittent androgen deprivation therapy. Our work helps to clarify under which circumstances adaptive therapy may be beneficial and suggests that turnover may play an unexpectedly important role in the decision-making process. SIGNIFICANCE: Tumor cell turnover modulates the speed of selection against drug resistance by amplifying the effects of competition and resistance costs; as such, turnover is an important factor in resistance management via adaptive therapy.See related commentary by Strobl et al., p. 811.
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Affiliation(s)
- Maximilian A R Strobl
- Department of Integrated Mathematical Oncology, H. Lee Moffitt Cancer Center, Tampa, Florida.
- Wolfson Centre for Mathematical Biology, University of Oxford, Oxford, Oxfordshire, United Kingdom
| | - Jeffrey West
- Department of Integrated Mathematical Oncology, H. Lee Moffitt Cancer Center, Tampa, Florida
| | - Yannick Viossat
- Ceremade, Université Paris-Dauphine, Université PSL, Paris, France
| | - Mehdi Damaghi
- Department of Cancer Physiology, H. Lee Moffitt Cancer Center, Tampa, Florida
| | - Mark Robertson-Tessi
- Department of Integrated Mathematical Oncology, H. Lee Moffitt Cancer Center, Tampa, Florida
| | - Joel S Brown
- Department of Integrated Mathematical Oncology, H. Lee Moffitt Cancer Center, Tampa, Florida
| | - Robert A Gatenby
- Department of Integrated Mathematical Oncology, H. Lee Moffitt Cancer Center, Tampa, Florida
- Cancer Biology and Evolution Program, H. Lee Moffitt Cancer Center, Tampa, Florida
| | - Philip K Maini
- Wolfson Centre for Mathematical Biology, University of Oxford, Oxford, Oxfordshire, United Kingdom
| | - Alexander R A Anderson
- Department of Integrated Mathematical Oncology, H. Lee Moffitt Cancer Center, Tampa, Florida.
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2
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Hosny S, Sahyon H, Youssef M, Negm A. Oleanolic Acid Suppressed DMBA-Induced Liver Carcinogenesis through Induction of Mitochondrial-Mediated Apoptosis and Autophagy. Nutr Cancer 2020; 73:968-982. [PMID: 32519911 DOI: 10.1080/01635581.2020.1776887] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Phytochemicals appeared as a rich source of efficient and safe agents against many diseases like cancer. Various herbal sources are rich in oleanolic acid (OA). The scope of this study was to assess the biochemical and molecular mechanisms implicated in the ameliorative potency of OA against DMBA-induced liver carcinogenesis. Forty-eight male albino mice were assigned randomly to five groups (eight mice each) as follows: control healthy group, olive oil group, OA group, DMBA group, and DMBA with OA. Apoptosis, autophagy, inflammation, proliferation, and angiogenesis were investigated in the tissue samples. Histopathological examination was carried out as well as liver enzymes activity and other hepatic antioxidant and inflammatory biomarkers. The treatment with OA effectively suppressed the DMBA-initiated liver carcinogenesis via modulation of antioxidant status, induction of apoptosis and autophagy through modulating the expression of Caspase-3, Bcl-2 and Beclin-1, inhibiting angiogenesis (VEGF), proliferation (PCNA), and improved liver function and histological picture with a reduction in AFP level. Additionally, OA applies its antitumor effects by inhibition of proinflammatory transcription factor NF-κB and inflammatory markers (TNF-α and Cox-2) associated with DMBA administration. The present study shows that OA treatment efficiently suppressed the DMBA-initiated liver carcinogenesis through induction of mitochondrial-mediated apoptosis and autophagy and modulating inflammation.
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Affiliation(s)
- Samar Hosny
- Chemistry Department, Biochemistry Division, Faculty of Science, Mansoura University, Mansoura, Egypt
| | - Heba Sahyon
- Chemistry Department, Faculty of Science, Kafrelsheikh University, Kafrelsheikh, Egypt
| | - Magdy Youssef
- Chemistry Department, Biochemistry Division, Faculty of Science, Mansoura University, Mansoura, Egypt
| | - Amr Negm
- Chemistry Department, Biochemistry Division, Faculty of Science, Mansoura University, Mansoura, Egypt.,Department of Chemistry, College of Science, King Faisal University, Al-Ahasa, Saudi Arabia
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3
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Paglia S, Sollazzo M, Di Giacomo S, Strocchi S, Grifoni D. Exploring MYC relevance to cancer biology from the perspective of cell competition. Semin Cancer Biol 2019; 63:49-59. [PMID: 31102666 DOI: 10.1016/j.semcancer.2019.05.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 05/08/2019] [Accepted: 05/14/2019] [Indexed: 12/13/2022]
Abstract
Cancer has long been regarded and treated as a foreign body appearing by mistake inside a living organism. However, now we know that cancer cells communicate with neighbours, thereby creating modified environments able to support their unusual need for nutrients and space. Understanding the molecular basis of these bi-directional interactions is thus mandatory to approach the complex nature of cancer. Since their discovery, MYC proteins have been showing to regulate a steadily increasing number of processes impacting cell fitness, and are consistently found upregulated in almost all human tumours. Of interest, MYC takes part in cell competition, an evolutionarily conserved fitness comparison strategy aimed at detecting weakened cells, which are then committed to death, removed from the tissue and replaced by fitter neighbours. During physiological development, MYC-mediated cell competition is engaged to eliminate cells with suboptimal MYC levels, so as to guarantee selective growth of the fittest and proper homeostasis, while transformed cells expressing high levels of MYC coopt cell competition to subvert tissue constraints, ultimately disrupting homeostasis. Therefore, the interplay between cells with different MYC levels may result in opposite functional outcomes, depending on the nature of the players. In the present review, we describe the most recent findings on the role of MYC-mediated cell competition in different contexts, with a special emphasis on its impact on cancer initiation and progression. We also discuss the relevance of competition-associated cell death to cancer disease.
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Affiliation(s)
- Simona Paglia
- CanceЯEvolutionLab, University of Bologna, Department of Pharmacy and Biotechnology, Via Selmi 3, 40126, Bologna, Italy.
| | - Manuela Sollazzo
- CanceЯEvolutionLab, University of Bologna, Department of Pharmacy and Biotechnology, Via Selmi 3, 40126, Bologna, Italy.
| | - Simone Di Giacomo
- CanceЯEvolutionLab, University of Bologna, Department of Pharmacy and Biotechnology, Via Selmi 3, 40126, Bologna, Italy.
| | - Silvia Strocchi
- CanceЯEvolutionLab, University of Bologna, Department of Pharmacy and Biotechnology, Via Selmi 3, 40126, Bologna, Italy.
| | - Daniela Grifoni
- CanceЯEvolutionLab, University of Bologna, Department of Pharmacy and Biotechnology, Via Selmi 3, 40126, Bologna, Italy.
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4
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Hochberg ME. An ecosystem framework for understanding and treating disease. EVOLUTION MEDICINE AND PUBLIC HEALTH 2018; 2018:270-286. [PMID: 30487969 PMCID: PMC6252061 DOI: 10.1093/emph/eoy032] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Accepted: 10/02/2018] [Indexed: 12/28/2022]
Abstract
Pathogens and cancers are pervasive health risks in the human population. I argue that if we are to better understand disease and its treatment, then we need to take an ecological perspective of disease itself. I generalize and extend an emerging framework that views disease as an ecosystem and many of its components as interacting in a community. I develop the framework for biological etiological agents (BEAs) that multiply within humans—focusing on bacterial pathogens and cancers—but the framework could be extended to include other host and parasite species. I begin by describing why we need an ecosystem framework to understand disease, and the main components and interactions in bacterial and cancer disease ecosystems. Focus is then given to the BEA and how it may proceed through characteristic states, including emergence, growth, spread and regression. The framework is then applied to therapeutic interventions. Central to success is preventing BEA evasion, the best known being antibiotic resistance and chemotherapeutic resistance in cancers. With risks of evasion in mind, I propose six measures that either introduce new components into the disease ecosystem or manipulate existing ones. An ecosystem framework promises to enhance our understanding of disease, BEA and host (co)evolution, and how we can improve therapeutic outcomes.
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Affiliation(s)
- Michael E Hochberg
- Institut des Sciences de l'Evolution, Université de Montpellier, 34095 Montpellier, France.,Santa Fe Institute, Santa Fe, NM 87501, USA.,Institute for Advanced Study in Toulouse, 31015 Toulouse, France
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5
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Buetti-Dinh A, Friedman R. Computer simulations of the signalling network in FLT3 +-acute myeloid leukaemia - indications for an optimal dosage of inhibitors against FLT3 and CDK6. BMC Bioinformatics 2018; 19:155. [PMID: 29699481 PMCID: PMC5921566 DOI: 10.1186/s12859-018-2145-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 04/03/2018] [Indexed: 12/31/2022] Open
Abstract
Background Mutations in the FMS-like tyrosine kinase 3 (FLT3) are associated with uncontrolled cellular functions that contribute to the development of acute myeloid leukaemia (AML). We performed computer simulations of the FLT3-dependent signalling network in order to study the pathways that are involved in AML development and resistance to targeted therapies. Results Analysis of the simulations revealed the presence of alternative pathways through phosphoinositide 3 kinase (PI3K) and SH2-containing sequence proteins (SHC), that could overcome inhibition of FLT3. Inhibition of cyclin dependent kinase 6 (CDK6), a related molecular target, was also tested in the simulation but was not found to yield sufficient benefits alone. Conclusions The PI3K pathway provided a basis for resistance to treatments. Alternative signalling pathways could not, however, restore cancer growth signals (proliferation and loss of apoptosis) to the same levels as prior to treatment, which may explain why FLT3 resistance mutations are the most common resistance mechanism. Finally, sensitivity analysis suggested the existence of optimal doses of FLT3 and CDK6 inhibitors in terms of efficacy and toxicity. Electronic supplementary material The online version of this article (10.1186/s12859-018-2145-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Antoine Buetti-Dinh
- Department of Chemistry and Biomedical Sciences, Linnæus University, Norra vägen 49, Kalmar, SE-391 82, Sweden.,Linnæus University Centre for Biomaterials Chemistry, Linnæus University, Norra vägen 49, Kalmar, SE-391 82, Sweden.,Centre for Ecology and Evolution in Microbial Model Systems, Linnæus University, Landgången 3, Kalmar, SE-391 82, Sweden.,Institute of Computational Science, Faculty of Informatics, Università della Svizzera Italiana, Via Giuseppe Buffi 13, Lugano, CH-6900, Switzerland.,Swiss Institute of Bioinformatics, Quartier Sorge - Batiment Genopode, Lausanne, CH-1015, Switzerland
| | - Ran Friedman
- Department of Chemistry and Biomedical Sciences, Linnæus University, Norra vägen 49, Kalmar, SE-391 82, Sweden. .,Linnæus University Centre for Biomaterials Chemistry, Linnæus University, Norra vägen 49, Kalmar, SE-391 82, Sweden.
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6
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Sadeeshkumar V, Duraikannu A, Ravichandran S, Kodisundaram P, Fredrick WS, Gobalakrishnan R. Modulatory efficacy of dieckol on xenobiotic-metabolizing enzymes, cell proliferation, apoptosis, invasion and angiogenesis during NDEA-induced rat hepatocarcinogenesis. Mol Cell Biochem 2017; 433:195-204. [PMID: 28397013 DOI: 10.1007/s11010-017-3027-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 04/01/2017] [Indexed: 12/25/2022]
Abstract
Dieckol (DEK) is a major polyphenol of marine brown seaweed Ecklonia cava which is a potential candidate for cancer therapy. However, the underlying mechanism of DEK as an anticancer drug remains to be elucidated. In this study, we evaluated the molecular mechanisms involved in the chemopreventive efficacy of DEK in N-nitrosodiethylamine (NDEA)-induced hepatocarcinogenesis rats by analyzing markers of xenobiotic-metabolizing enzymes (XMEs), apoptosis, invasion, and angiogenesis. Rats administered NDEA developed hepatocarcinogenesis that displayed apoptosis avoidance coupled to upregulation of pro-inflammatory, invasion, and angiogenesis markers. Treatment of DEK effectively suppressed the NDEA-initiated hepatocarcinogenesis by modulation of XMEs, inducing of apoptosis via the mitochondrial pathway as revealed by modulating the Bcl-2 family proteins, cytochrome C, caspases, and inhibiting invasion, and angiogenesis as evidenced by changes in the activities of MMPs (MMP2/9) and the expression of VEGF. In addition, DEK exerts its anticancer effects via inhibition of pro-inflammatory transcription factor NF-κB (nuclear factor κB) and COX2 in NDEA-induced hepatocarcinogenesis. Taken together, this study demonstrates that DEK modulates the expression of key molecules that regulate apoptosis, inflammation, invasion, and angiogenesis. These results strongly indicate that DEK from E. cava is an attractive candidate for chemoprevention.
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Affiliation(s)
- Velayutham Sadeeshkumar
- Centre of Advanced Study in Marine Biology, Faculty of Marine Sciences, Annamalai University, Parangipettai, Chidambaram, Tamil Nadu, 608 502, India.
- Department of Biochemistry and Biotechnology, Faculty of Science, Annamalai University, Chidambaram, Tamil Nadu, 608 002, India.
| | - Arul Duraikannu
- Department of Biochemistry and Biotechnology, Faculty of Science, Annamalai University, Chidambaram, Tamil Nadu, 608 002, India
- Division of Neurology, Department of Medicine, University of Alberta, Edmonton, AB, T6G 2G3, Canada
| | - Samuthrapandian Ravichandran
- Centre of Advanced Study in Marine Biology, Faculty of Marine Sciences, Annamalai University, Parangipettai, Chidambaram, Tamil Nadu, 608 502, India
| | - Paulrasu Kodisundaram
- Department of Chemistry, Faculty of Science, Annamalai University, Chidambaram, Tamil Nadu, 608 002, India
| | - Wilson Sylvester Fredrick
- Centre of Advanced Study in Marine Biology, Faculty of Marine Sciences, Annamalai University, Parangipettai, Chidambaram, Tamil Nadu, 608 502, India
| | - Rajagopal Gobalakrishnan
- Centre of Advanced Study in Marine Biology, Faculty of Marine Sciences, Annamalai University, Parangipettai, Chidambaram, Tamil Nadu, 608 502, India
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7
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Akhmetzhanov AR, Hochberg ME. Dynamics of preventive vs post-diagnostic cancer control using low-impact measures. eLife 2015; 4:e06266. [PMID: 26111339 PMCID: PMC4524440 DOI: 10.7554/elife.06266] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2014] [Accepted: 06/24/2015] [Indexed: 01/23/2023] Open
Abstract
Cancer poses danger because of its unregulated growth, development of resistance, and metastatic spread to vital organs. We currently lack quantitative theory for how preventive measures and post-diagnostic interventions are predicted to affect risks of a life threatening cancer. Here we evaluate how continuous measures, such as life style changes and traditional treatments, affect both neoplastic growth and the frequency of resistant clones. We then compare and contrast preventive and post-diagnostic interventions assuming that only a single lesion progresses to invasive carcinoma during the life of an individual, and resection either leaves residual cells or metastases are undetected. Whereas prevention generally results in more positive therapeutic outcomes than post-diagnostic interventions, this advantage is substantially lowered should prevention initially fail to arrest tumour growth. We discuss these results and other important mitigating factors that should be taken into consideration in a comparative understanding of preventive and post-diagnostic interventions. DOI:http://dx.doi.org/10.7554/eLife.06266.001 About one person in every two will get cancer during their lives. Surgery and chemotherapy have long been mainstays of cancer treatment. Both, however, have substantial downsides. Surgery may leave behind undetected cancer cells that can grow into new tumours. Furthermore, in response to chemotherapy drugs, some cancer cells may emerge that resist further treatment. There is therefore interest in whether preventive strategies—including lifestyle changes and medications—could reduce the likelihood of confronting a life-threatening cancer. Now, Akhmetzhanov and Hochberg have developed a mathematical model to help compare the effectiveness of preventive strategies and traditional cancer treatments. The model—which assumes that a person can only develop a single cancer from a single region of pre-cancerous cells—suggests that long-term cancer prevention strategies reduce the risk of a life-threatening cancer by more than traditional treatment that begins after a tumour is discovered. The preventive measures may be less effective in some cases compared to traditional treatments if they initially fail to stop a tumour growing, although on average they still work better than treating the cancer after detection. According to Akhmetzhanov and Hochberg's model, surgical removal followed by chemotherapy is less likely to be successful than prevention, and when successful, requires larger impacts on the cancer (and therefore creates more side-effects for the patient) to achieve the same level of control as prevention. The model also suggests that even at very low levels of impact on residual cancer cells, chemotherapies are likely to be counterproductive by boosting the subsequent emergence of treatment-resistant tumours. Akhmetzhanov and Hochberg's model predicts how effective preventive measures need to be in terms of slowing the growth of cancer cells to result in given reductions in the future risk of a life-threatening cancer. Future work should test this model by measuring the effects on tumour growth of prevention and of traditional therapies. DOI:http://dx.doi.org/10.7554/eLife.06266.002
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Affiliation(s)
- Andrei R Akhmetzhanov
- Institut des Sciences de l'Evolution de Montpellier, University of Montpellier, Montpellier, France
| | - Michael E Hochberg
- Institut des Sciences de l'Evolution de Montpellier, University of Montpellier, Montpellier, France
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8
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Labi V, Erlacher M. How cell death shapes cancer. Cell Death Dis 2015; 6:e1675. [PMID: 25741600 PMCID: PMC4385913 DOI: 10.1038/cddis.2015.20] [Citation(s) in RCA: 181] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 12/28/2014] [Accepted: 01/02/2015] [Indexed: 12/20/2022]
Abstract
Apoptosis has been established as a mechanism of anti-cancer defense. Members of the BCL-2 family are critical mediators of apoptotic cell death in health and disease, often found to be deregulated in cancer and believed to lead to the survival of malignant clones. However, over the years, a number of studies pointed out that a model in which cell death resistance unambiguously acts as a barrier against malignant disease might be too simple. This is based on paradoxical observations made in tumor patients as well as mouse models indicating that apoptosis can indeed drive tumor formation, at least under certain circumstances. One possible explanation for this phenomenon is that apoptosis can promote proliferation critically needed to compensate for cell loss, for example, upon therapy, and to restore tissue homeostasis. However, this, at the same time, can promote tumor development by allowing expansion of selected clones. Usually, tissue resident stem/progenitor cells are a major source for repopulation, some of them potentially carrying (age-, injury- or therapy-induced) genetic aberrations deleterious for the host. Thereby, apoptosis might drive genomic instability by facilitating the emergence of pathologic clones during phases of proliferation and subsequent replication stress-associated DNA damage. Tumorigenesis initiated by repeated cell attrition and repopulation, as confirmed in different genetic models, has parallels in human cancers, exemplified in therapy-induced secondary malignancies and myelodysplastic syndromes in patients with congenital bone marrow failure syndromes. Here, we aim to review evidence in support of the oncogenic role of stress-induced apoptosis.
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Affiliation(s)
- V Labi
- Max-Delbrück-Center for Molecular Medicine (MDC), Berlin 13125, Germany
- Immune Regulation and Cancer, Max-Delbrück-Center for Molecular Medicine, Robert Rössle-Strasse 10, 13125 Berlin, Germany. Tel: +49 30 9406 3462; Fax: +49 30 9406 2390; E-mail:
| | - M Erlacher
- Department of Pediatrics and Adolescent Medicine, Division of Pediatric Hematology and Oncology, University Medical Center of Freiburg, Freiburg 79106, Germany
- Freiburg Institute for Advanced Studies, University of Freiburg, Freiburg 79104, Germany
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9
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Foo J, Leder K, Ryser MD. Multifocality and recurrence risk: a quantitative model of field cancerization. J Theor Biol 2014; 355:170-84. [PMID: 24735903 PMCID: PMC4589890 DOI: 10.1016/j.jtbi.2014.02.042] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Revised: 02/13/2014] [Accepted: 02/24/2014] [Indexed: 10/25/2022]
Abstract
Primary tumors often emerge within genetically altered fields of premalignant cells that appear histologically normal but have a high chance of progression to malignancy. Clinical observations have suggested that these premalignant fields pose high risks for emergence of recurrent tumors if left behind after surgical removal of the primary tumor. In this work, we develop a spatio-temporal stochastic model of epithelial carcinogenesis, combining cellular dynamics with a general framework for multi-stage genetic progression to cancer. Using the model, we investigate how various properties of the premalignant fields depend on microscopic cellular properties of the tissue. In particular, we provide analytic results for the size-distribution of the histologically undetectable premalignant fields at the time of diagnosis, and investigate how the extent and the geometry of these fields depend upon key groups of parameters associated with the tissue and genetic pathways. We also derive analytical results for the relative risks of local vs. distant secondary tumors for different parameter regimes, a critical aspect for the optimal choice of post-operative therapy in carcinoma patients. This study contributes to a growing literature seeking to obtain a quantitative understanding of the spatial dynamics in cancer initiation.
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Affiliation(s)
- Jasmine Foo
- School of Mathematics, University of Minnesota, Minneapolis, MN, United States.
| | - Kevin Leder
- Industrial and Systems Engineering, University of Minnesota, Minneapolis, MN, United States
| | - Marc D Ryser
- Department of Mathematics, Duke University, Durham, NC, United States
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10
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Monteagudo Á, Santos J. Studying the capability of different cancer hallmarks to initiate tumor growth using a cellular automaton simulation. Application in a cancer stem cell context. Biosystems 2013; 115:46-58. [PMID: 24262634 DOI: 10.1016/j.biosystems.2013.11.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Revised: 10/29/2013] [Accepted: 11/03/2013] [Indexed: 02/06/2023]
Abstract
We used a cellular automaton model for cancer growth simulation at cellular level, based on the presence of different cancer hallmarks acquired by the cells. The presence of the hallmarks in each of the cells determines cell mitotic and apoptotic behaviors. Depending on the presence of the different hallmarks and some associated parameters of the hallmarks, the system can evolve to different dynamics. We used the cellular automaton model to inspect the capability of different hallmarks to generate tumor growth in different conditions, using this study in a cancer stem cell context to analyze the capability of the hallmarks to tumor regrowth in different circumstances.
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Affiliation(s)
- Ángel Monteagudo
- University of A Coruña, Department of Computer Science, Campus de Elviña s/n, 15071 A Coruña, Spain
| | - José Santos
- University of A Coruña, Department of Computer Science, Campus de Elviña s/n, 15071 A Coruña, Spain.
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11
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Enderling H, Hlatky L, Hahnfeldt P. Immunoediting: evidence of the multifaceted role of the immune system in self-metastatic tumor growth. Theor Biol Med Model 2012; 9:31. [PMID: 22838395 PMCID: PMC3499182 DOI: 10.1186/1742-4682-9-31] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Accepted: 05/16/2012] [Indexed: 02/07/2023] Open
Abstract
Background The role of the immune system in tumor progression has been a subject for discussion for many decades. Numerous studies suggest that a low immune response might be beneficial, if not necessary, for tumor growth, and only a strong immune response can counter tumor growth and thus inhibit progression. Methods We implement a cellular automaton model previously described that captures the dynamical interactions between the cancer stem and non-stem cell populations of a tumor through a process of self-metastasis. By overlaying on this model the diffusion of immune reactants into the tumor from a peripheral source to target cells, we simulate the process of immune-system-induced cell kill on tumor progression. Results A low cytotoxic immune reaction continuously kills cancer cells and, although at a low rate, thereby causes the liberation of space-constrained cancer stem cells to drive self-metastatic progression and continued tumor growth. With increasing immune system strength, however, tumor growth peaks, and then eventually falls below the intrinsic tumor sizes observed without an immune response. With this increasing immune response the number and proportion of cancer stem cells monotonically increases, implicating an additional unexpected consequence, that of cancer stem cell selection, to the immune response. Conclusions Cancer stem cells and immune cytotoxicity alone are sufficient to explain the three-step “immunoediting” concept – the modulation of tumor growth through inhibition, selection and promotion.
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Affiliation(s)
- Heiko Enderling
- Center of Cancer Systems Biology, Steward St, Elizabeth's Medical Center, Tufts University School of Medicine, 736 Cambridge Street, Boston, MA 02135, USA
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12
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Qiu W, Wang X, Leibowitz B, Yang W, Zhang L, Yu J. PUMA-mediated apoptosis drives chemical hepatocarcinogenesis in mice. Hepatology 2011; 54:1249-58. [PMID: 21725994 PMCID: PMC3184207 DOI: 10.1002/hep.24516] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
UNLABELLED Hepatocyte death and proliferation contribute to hepatocellular carcinoma development after carcinogen exposure or chronic liver inflammation. However, the role and the molecular targets of hepatocyte death in relation to compensatory proliferation have not been fully characterized. In this study, we investigated the role of p53 up-regulated modulator of apoptosis (PUMA), a BH3-only protein important for both p53-dependent and -independent apoptosis, in a diethylnitrosamine (DEN)-induced liver carcinogenesis model. PUMA deficiency significantly decreased the multiplicity and size of liver tumors. DEN treatment induced p53-independent PUMA expression, PUMA-dependent hepatocyte death, and compensatory proliferation. Furthermore, inhibition or deletion of c-jun N-terminal kinase 1 (JNK1) abrogated PUMA induction, hepatocyte death, and compensatory proliferation. CONCLUSION These results provide direct evidence that JNK1/PUMA-dependent apoptosis promotes chemical hepatocarcinogenesis through compensatory proliferation, and suggest apoptotic inducers as potential therapeutic targets in liver injury and cancer.
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Affiliation(s)
- Wei Qiu
- Department of Pathology, University of Pittsburgh School of Medicine, University of Pittsburgh Cancer Institute, 5117 Centre Ave., Pittsburgh, PA 15213, USA
| | - Xinwei Wang
- Department of Pathology, University of Pittsburgh School of Medicine, University of Pittsburgh Cancer Institute, 5117 Centre Ave., Pittsburgh, PA 15213, USA
| | - Brian Leibowitz
- Department of Pathology, University of Pittsburgh School of Medicine, University of Pittsburgh Cancer Institute, 5117 Centre Ave., Pittsburgh, PA 15213, USA
| | - Wancai Yang
- University of Illinois at Chicago, Department of Pathology, 840 S. Wood Street, Chicago, IL 60612
| | - Lin Zhang
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, University of Pittsburgh Cancer Institute, 5117 Centre Ave., Pittsburgh, PA 15213, USA
| | - Jian Yu
- Department of Pathology, University of Pittsburgh School of Medicine, University of Pittsburgh Cancer Institute, 5117 Centre Ave., Pittsburgh, PA 15213, USA,Correspondence: Jian Yu, Ph.D., Hillman Cancer Center Research Pavilion, Suite 2.26h, 5117 Centre Ave, Pittsburgh, PA 15213. ; Phone: 412-623-7786; Fax: 412-623-7778
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13
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Cancer stem cells in solid tumors: is 'evading apoptosis' a hallmark of cancer? PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2011; 106:391-9. [PMID: 21473880 DOI: 10.1016/j.pbiomolbio.2011.03.007] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Conventional wisdom has long held that once a cancer cell has developed it will inevitably progress to clinical disease. Updating this paradigm, it has more recently become apparent that the tumor interacts with its microenvironment and that some environmental bottlenecks, such as the angiogenic switch, must be overcome for the tumor to progress. In parallel, attraction has been drawn to the concept that there is a minority population of cells - the cancer stem cells - bestowed with the exclusive ability to self-renew and regenerate the tumor. With therapeutic targeting issues at stake, much attention has shifted to the identification of cancer stem cells, the thinking being that the remaining non-stem population, already fated to die, will play a negligible role in tumor development. In fact, the newly appreciated importance of intercellular interactions in cancer development also extends in a unique and unexpected way to interactions between the stem and non-stem compartments of the tumor. Here we discuss recent findings drawn from a hybrid mathematical-cellular automaton model that simulates growth of a heterogeneous solid tumor comprised of cancer stem cells and non-stem cancer cells. The model shows how the introduction of cell fate heterogeneity paradoxically influences the tumor growth dynamic in response to apoptosis, to reveal yet another bottleneck to tumor progression potentially exploitable for disease control.
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Wang C, Tai Y, Lisanti MP, Liao DJ. c-Myc induction of programmed cell death may contribute to carcinogenesis: a perspective inspired by several concepts of chemical carcinogenesis. Cancer Biol Ther 2011; 11:615-26. [PMID: 21278493 DOI: 10.4161/cbt.11.7.14688] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The c-Myc protein, encoded by c-myc gene, in its wild-type form can induce tumors with a high frequency and can induce massive programmed cell death (PCD) in most transgenic mouse models, with greater efficiency than other oncogenes. Evidence also indicates that c-Myc can cause proliferative inhibition, i.e. mitoinhibition. The c-Myc-induced PCD and mitoinhibition, which may be attributable to its inhibition of cyclin D1 and induction of p53, may impose a pressure of compensatory proliferation, i.e. regeneration, onto the initiated cells (cancer progenitor cells) that occur sporadically and are resistant to the mitoinhibition. The initiated cells can thus proliferate robustly and progress to a malignancy. This hypothetical thinking, i.e. the concurrent PCD and mitoinhibition induced by c-Myc can promote carcinogenesis, predicts that an optimal balance is achieved between cell death and ensuing regeneration during oncogenic transformation by c-Myc, which can better promote carcinogenesis. In this perspective, we summarize accumulating evidence and challenge the current model that oncoprotein induces carcinogenesis by promoting cellular proliferation and/or inhibiting PCD. Inspired by c-myc oncogene, we surmise that many tumor-suppressive or growth-inhibitory genes may also be able to promote carcinogenesis in a similar way, i.e. by inducing PCD and/or mitoinhibition of normal cells to create a need for compensatory proliferation that drives a robust replication of initiating cells.
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Affiliation(s)
- Chenguang Wang
- Department of Stem Cell and Regenerative Medicine, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, USA
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Abstract
Most human cancer types result from the accumulation of multiple genetic and epigenetic alterations in a single cell. Once the first change (or changes) have arisen, tumorigenesis is initiated and the subsequent emergence of additional alterations drives progression to more aggressive and ultimately invasive phenotypes. Elucidation of the dynamics of cancer initiation is of importance for an understanding of tumor evolution and cancer incidence data. In this paper, we develop a novel mathematical framework to study the processes of cancer initiation. Cells at risk of accumulating oncogenic mutations are organized into small compartments of cells and proliferate according to a stochastic process. During each cell division, an (epi)genetic alteration may arise which leads to a random fitness change, drawn from a probability distribution. Cancer is initiated when a cell gains a fitness sufficiently high to escape from the homeostatic mechanisms of the cell compartment. To investigate cancer initiation during a human lifetime, a 'race' between this fitness process and the aging process of the patient is considered; the latter is modeled as a second stochastic Markov process in an aging dimension. This model allows us to investigate the dynamics of cancer initiation and its dependence on the mutational fitness distribution. Our framework also provides a methodology to assess the effects of different life expectancy distributions on lifetime cancer incidence. We apply this methodology to colorectal tumorigenesis while considering life expectancy data of the US population to inform the dynamics of the aging process. We study how the probability of cancer initiation prior to death, the time until cancer initiation, and the mutational profile of the cancer-initiating cell depends on the shape of the mutational fitness distribution and life expectancy of the population.
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Affiliation(s)
- Jasmine Foo
- Department of Biostatistics and Computational Biology, Dana-Farber Cancer Institute, Boston, MA 02115, USA
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The enigmatic roles of caspases in tumor development. Cancers (Basel) 2010; 2:1952-79. [PMID: 24281211 PMCID: PMC3840446 DOI: 10.3390/cancers2041952] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Revised: 11/16/2010] [Accepted: 11/23/2010] [Indexed: 12/25/2022] Open
Abstract
One function ascribed to apoptosis is the suicidal destruction of potentially harmful cells, such as cancerous cells. Hence, their growth depends on evasion of apoptosis, which is considered as one of the hallmarks of cancer. Apoptosis is ultimately carried out by the sequential activation of initiator and executioner caspases, which constitute a family of intracellular proteases involved in dismantling the cell in an ordered fashion. In cancer, therefore, one would anticipate caspases to be frequently rendered inactive, either by gene silencing or by somatic mutations. From clinical data, however, there is little evidence that caspase genes are impaired in cancer. Executioner caspases have only rarely been found mutated or silenced, and also initiator caspases are only affected in particular types of cancer. There is experimental evidence from transgenic mice that certain initiator caspases, such as caspase-8 and -2, might act as tumor suppressors. Loss of the initiator caspase of the intrinsic apoptotic pathway, caspase-9, however, did not promote cellular transformation. These data seem to question a general tumor-suppressive role of caspases. We discuss several possible ways how tumor cells might evade the need for alterations of caspase genes. First, alternative splicing in tumor cells might generate caspase variants that counteract apoptosis. Second, in tumor cells caspases might be kept in check by cellular caspase inhibitors such as c-FLIP or XIAP. Third, pathways upstream of caspase activation might be disrupted in tumor cells. Finally, caspase-independent cell death mechanisms might abrogate the selection pressure for caspase inactivation during tumor development. These scenarios, however, are hardly compatible with the considerable frequency of spontaneous apoptosis occurring in several cancer types. Therefore, alternative concepts might come into play, such as compensatory proliferation. Herein, apoptosis and/or non-apoptotic functions of caspases may even promote tumor development. Moreover, experimental evidence suggests that caspases might play non-apoptotic roles in processes that are crucial for tumorigenesis, such as cell proliferation, migration, or invasion. We thus propose a model wherein caspases are preserved in tumor cells due to their functional contributions to development and progression of tumors.
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Vinothini G, Murugan RS, Nagini S. Mitochondria-mediated apoptosis in patients with adenocarcinoma of the breast: Correlation with histological grade and menopausal status. Breast 2010; 20:86-92. [PMID: 20829044 DOI: 10.1016/j.breast.2010.08.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2010] [Revised: 08/05/2010] [Accepted: 08/11/2010] [Indexed: 01/13/2023] Open
Abstract
The present study was designed to investigate the abnormalities in the expression of apoptosis-associated proteins that lead to the progression of breast cancer. Sixty breast cancer patients histologically categorized as grade I, II and III, and as pre- and post-menopausal were chosen for the study. We analyzed the expression of the anti-apoptotic and pro-apoptotic Bcl-2 family proteins as well as cytochrome C, Apaf-1 and caspases in tumour and adjacent tissues by immunohistochemical and Western blot analyses. The breast tumours analyzed in the present study were characterized by increased expression of Bcl-2, Bcl-xL and Mcl-1, associated with downregulation in the expression of Bax, cytosolic cytochrome C, Apaf-1 and caspases. The magnitude of the changes was however more pronounced in premenopausal patients and in grade III tumours. The results of the present study confirm that differential expression patterns of Bcl-2 family proteins and caspases are involved in evasion of apoptosis and in the progression of breast cancer.
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Affiliation(s)
- Govindarajah Vinothini
- Department of Biochemistry and Biotechnology, Faculty of Science, Annamalai University, Annamalainagar, Tamil Nadu, India
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Durrett R, Foo J, Leder K, Mayberry J, Michor F. Evolutionary dynamics of tumor progression with random fitness values. Theor Popul Biol 2010; 78:54-66. [PMID: 20488197 DOI: 10.1016/j.tpb.2010.05.001] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2010] [Revised: 05/10/2010] [Accepted: 05/10/2010] [Indexed: 11/19/2022]
Abstract
Most human tumors result from the accumulation of multiple genetic and epigenetic alterations in a single cell. Mutations that confer a fitness advantage to the cell are known as driver mutations and are causally related to tumorigenesis. Other mutations, however, do not change the phenotype of the cell or even decrease cellular fitness. While much experimental effort is being devoted to the identification of the functional effects of individual mutations, mathematical modeling of tumor progression generally considers constant fitness increments as mutations are accumulated. In this paper we study a mathematical model of tumor progression with random fitness increments. We analyze a multi-type branching process in which cells accumulate mutations whose fitness effects are chosen from a distribution. We determine the effect of the fitness distribution on the growth kinetics of the tumor. This work contributes to a quantitative understanding of the accumulation of mutations leading to cancer.
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Affiliation(s)
- Rick Durrett
- Department of Mathematics, Cornell University, Ithaca, NY 14853, United States
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Manikandan P, Murugan RS, Priyadarsini RV, Vinothini G, Nagini S. Eugenol induces apoptosis and inhibits invasion and angiogenesis in a rat model of gastric carcinogenesis induced by MNNG. Life Sci 2010; 86:936-41. [PMID: 20434464 DOI: 10.1016/j.lfs.2010.04.010] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2009] [Revised: 04/15/2010] [Accepted: 04/21/2010] [Indexed: 12/12/2022]
Abstract
AIMS Combining apoptosis induction with anti-invasive and anti-angiogenic treatment is gaining increasing attention as a promising strategy for cancer chemoprevention. In the present study, eugenol (4-allyl-2-methoxyphenol) was evaluated for its chemopreventive effects on N-methyl-N(')-nitro-N-nitrosoguanidine (MNNG)-induced gastric carcinogenesis in Wistar rats by analyzing markers of apoptosis, invasion and angiogenesis. MAIN METHODS The expressions of markers of apoptosis (Bcl-2, Bcl-xL, Bax, Apaf-1, cytochrome C, caspase-9, caspase-3 and poly(ADP-ribose)polymerase; PARP), invasion (matrix metalloproteinase-2; MMP-2, matrix metalloproteinase-9; MMP-9, reversion-inducing cysteine rich protein with Kazal motifs; RECK and tissue inhibitors of metalloproteinase-2; TIMP-2) and angiogenesis (vascular endothelial growth factor; VEGF and VEGF receptor1; VEGFR1) in stomach tissue of experimental and control animals were measured by gelatin zymogram, immunohistochemical, Western blot and RT-PCR analysis. KEY FINDINGS Rats administered MNNG developed gastric carcinomas that displayed apoptosis avoidance coupled to upregulation of pro-invasive and angiogenic factors. Administration of eugenol induced apoptosis via the mitochondrial pathway by modulating the Bcl-2 family proteins, Apaf-1, cytochrome C, and caspases and inhibiting invasion, and angiogenesis as evidenced by changes in the activities of MMPs and the expression of MMP-2 and -9, VEGF, VEGFR1, TIMP-2 and RECK. SIGNIFICANCE Phytochemicals such as eugenol that are capable of manipulating the equilibrium between pro- and anti-apoptotic proteins as well as the delicate balance between stimulators and inhibitors of invasion and angiogenesis are attractive candidates for preventing tumour progression.
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Affiliation(s)
- Palrasu Manikandan
- Department of Biochemistry and Biotechnology, Faculty of Science, Annamalai University, Annamalainagar-608 002, Tamil Nadu, India
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Kreeger PK, Lauffenburger DA. Cancer systems biology: a network modeling perspective. Carcinogenesis 2010; 31:2-8. [PMID: 19861649 PMCID: PMC2802670 DOI: 10.1093/carcin/bgp261] [Citation(s) in RCA: 232] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2009] [Revised: 10/17/2009] [Accepted: 10/18/2009] [Indexed: 12/28/2022] Open
Abstract
Cancer is now appreciated as not only a highly heterogenous pathology with respect to cell type and tissue origin but also as a disease involving dysregulation of multiple pathways governing fundamental cell processes such as death, proliferation, differentiation and migration. Thus, the activities of molecular networks that execute metabolic or cytoskeletal processes, or regulate these by signal transduction, are altered in a complex manner by diverse genetic mutations in concert with the environmental context. A major challenge therefore is how to develop actionable understanding of this multivariate dysregulation, with respect both to how it arises from diverse genetic mutations and to how it may be ameliorated by prospective treatments. While high-throughput experimental platform technologies ranging from genomic sequencing to transcriptomic, proteomic and metabolomic profiling are now commonly used for molecular-level characterization of tumor cells and surrounding tissues, the resulting data sets defy straightforward intuitive interpretation with respect to potential therapeutic targets or the effects of perturbation. In this review article, we will discuss how significant advances can be obtained by applying computational modeling approaches to elucidate the pathways most critically involved in tumor formation and progression, impact of particular mutations on pathway operation, consequences of altered cell behavior in tissue environments and effects of molecular therapeutics.
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Affiliation(s)
| | - Douglas A. Lauffenburger
- Department of Biological Engineering, Massachusetts Institute of Technology, Building 16, Room 343, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
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Enderling H, Anderson AR, Chaplain MA, Beheshti A, Hlatky L, Hahnfeldt P. Paradoxical Dependencies of Tumor Dormancy and Progression on Basic Cell Kinetics. Cancer Res 2009; 69:8814-21. [DOI: 10.1158/0008-5472.can-09-2115] [Citation(s) in RCA: 136] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Abstract
As Theodosius Dobzhansky famously noted in 1973, "Nothing in biology makes sense except in the light of evolution," and cancer is no exception to this rule. Our understanding of cancer initiation, progression, treatment, and resistance has advanced considerably by regarding cancer as the product of evolutionary processes. Here we review the literature of mathematical models of cancer evolution and provide a synthesis and discussion of the field.
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Intracellular redox status and oxidative stress: implications for cell proliferation, apoptosis, and carcinogenesis. Arch Toxicol 2008; 82:273-99. [PMID: 18443763 DOI: 10.1007/s00204-008-0304-z] [Citation(s) in RCA: 303] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2008] [Accepted: 04/03/2008] [Indexed: 02/06/2023]
Abstract
Oxidative stress can be defined as the imbalance between cellular oxidant species production and antioxidant capability. Reactive oxygen species (ROS) are involved in a variety of different cellular processes ranging from apoptosis and necrosis to cell proliferation and carcinogenesis. In fact, molecular events, such as induction of cell proliferation, decreased apoptosis, and oxidative DNA damage have been proposed to be critically involved in carcinogenesis. Carcinogenicity and aging are characterized by a set of complex endpoints, which appear as a series of molecular reactions. ROS can modify many intracellular signaling pathways including protein phosphatases, protein kinases, and transcription factors, suggesting that the majority of the effects of ROS are through their actions on signaling pathways rather than via non-specific damage of macromolecules; however, exact mechanisms by which redox status induces cells to proliferate or to die, and how oxidative stress can lead to processes evoking tumor formation are still under investigation.
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Jäger R. Targeting the death machinery in mammary epithelial cells: Implications for breast cancer from transgenic and tissue culture experiments. Crit Rev Oncol Hematol 2007; 63:231-40. [PMID: 17604639 DOI: 10.1016/j.critrevonc.2007.05.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2006] [Revised: 05/08/2007] [Accepted: 05/23/2007] [Indexed: 12/11/2022] Open
Abstract
Apoptosis plays important roles in the development of the mammary gland, and its impairment has been speculated to promote breast cancer. In mammary epithelial cells apoptosis is triggered via the intrinsic pathway which is controlled by interactions between pro- and anti-apoptotic members of the Bcl-2 protein family. The impact of impairing this pathway on the development of breast cancer has been addressed experimentally using transgenic mouse models. Neither overexpression of anti-apoptotic Bcl-2 nor a deficiency of pro-apoptotic Bax were tumorigenic on their own in mammary glands of transgenic mice. Both ways of impairing apoptosis, however, promoted mammary tumorigenesis elicited by c-myc or SV40 T antigen. Likewise, inhibition of the intrinsic pathway in a three-dimensional mammary tissue culture model was insufficient to generate solid aggregates resembling early breast cancer stages but required the concomitant activity of proliferation-stimulating oncogenes. These two experimental approaches have thus substantiated the concept of apoptosis acting as a tumor suppressor mechanism, however point towards a complex picture in which alternative routes to cell death may be involved.
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Affiliation(s)
- Richard Jäger
- Department of Developmental Pathology, Institute for Pathology, Bonn Medical School, Sigmund-Freud-Strasse 25, 53127 Bonn, Germany.
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