1
|
Bassett JK, MacInnis RJ, Yang Y, Hodge AM, Lynch BM, English DR, Giles GG, Milne RL, Jayasekara H. Alcohol intake trajectories during the life course and risk of alcohol-related cancer: A prospective cohort study. Int J Cancer 2022; 151:56-66. [PMID: 35182083 DOI: 10.1002/ijc.33973] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 01/26/2022] [Accepted: 01/28/2022] [Indexed: 11/10/2022]
Abstract
We examined associations between sex-specific alcohol intake trajectories and alcohol-related cancer risk using data from 22 756 women and 15 701 men aged 40 to 69 years at baseline in the Melbourne Collaborative Cohort Study. Alcohol intake for 10-year periods from age 20 until the decade encompassing recruitment, calculated using recalled beverage-specific frequency and quantity, was used to estimate group-based sex-specific intake trajectories. Hazard ratios (HR) and 95% confidence intervals (CI) were estimated for primary invasive alcohol-related cancer (upper aerodigestive tract, breast, liver and colorectum). Three distinct alcohol intake trajectories for women (lifetime abstention, stable light, increasing moderate) and six for men (lifetime abstention, stable light, stable moderate, increasing heavy, early decreasing heavy, late decreasing heavy) were identified. 2303 incident alcohol-related cancers were diagnosed during 485 525 person-years in women and 789 during 303 218 person-years in men. For men, compared with lifetime abstention, heavy intake (mean ≥ 60 g/day) at age 20 to 39 followed by either an early (from age 40 to 49) (early decreasing heavy; HR = 1.75, 95% CI: 1.25-2.44) or late decrease (from age 60 to 69) (late decreasing heavy; HR = 1.94, 95% CI: 1.28-2.93), and moderate intake (mean <60 g/day) at age 20 to 39 increasing to heavy intake in middle-age (increasing heavy; HR = 1.45, 95% CI: 1.06-1.97) were associated with increased risk of alcohol-related cancer. For women, compared with lifetime abstention, increasing intake from age 20 (increasing moderate) was associated with increased alcohol-related cancer risk (HR = 1.25, 95% CI: 1.06-1.48). Similar associations were observed for colorectal (men) and breast cancer. Heavy drinking during early adulthood might increase cancer risk later in life.
Collapse
Affiliation(s)
- Julie K Bassett
- Cancer Epidemiology Division, Cancer Council Victoria, Melbourne, Victoria, Australia
| | - Robert J MacInnis
- Cancer Epidemiology Division, Cancer Council Victoria, Melbourne, Victoria, Australia
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Victoria, Australia
| | - Yi Yang
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Victoria, Australia
| | - Allison M Hodge
- Cancer Epidemiology Division, Cancer Council Victoria, Melbourne, Victoria, Australia
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Victoria, Australia
| | - Brigid M Lynch
- Cancer Epidemiology Division, Cancer Council Victoria, Melbourne, Victoria, Australia
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Victoria, Australia
- Physical Activity Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Dallas R English
- Cancer Epidemiology Division, Cancer Council Victoria, Melbourne, Victoria, Australia
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Victoria, Australia
| | - Graham G Giles
- Cancer Epidemiology Division, Cancer Council Victoria, Melbourne, Victoria, Australia
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Victoria, Australia
- Precision Medicine, School of Clinical Sciences at Monash Health, Monash University, Clayton, Victoria, Australia
| | - Roger L Milne
- Cancer Epidemiology Division, Cancer Council Victoria, Melbourne, Victoria, Australia
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Victoria, Australia
- Precision Medicine, School of Clinical Sciences at Monash Health, Monash University, Clayton, Victoria, Australia
| | - Harindra Jayasekara
- Cancer Epidemiology Division, Cancer Council Victoria, Melbourne, Victoria, Australia
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Victoria, Australia
- School of Public Health and Preventive Medicine, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria, Australia
| |
Collapse
|
2
|
Nagah A, Amer A. Different Mechanisms of Cigarette Smoking-Induced Lung Cancer. Acta Biotheor 2021; 69:37-52. [PMID: 32979115 DOI: 10.1007/s10441-020-09394-9] [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: 10/11/2019] [Accepted: 09/14/2020] [Indexed: 10/23/2022]
Abstract
The risk of cigarette smoking plays a pivotal role in increasing the incidence rates of lung cancer. This paper sheds new light on modeling the impact of cigarette smoking on lung cancer evolution, especially genetic instability and the number of gene mutations in the genome of stem cells. To handle this issue, we have set up stochastic multi-stage models to fit the data set of the probabilities of current and former smokers from the Nurses' Health Study cohort of females (NHS) and the Health Professionals Follow up Study cohort of men (HPFS). Throughout this paper, we consider both mutation rates and clonal expansion rates as parameters in each compartment. For current and former smokers, three-driver mutations are most likely to take place in the progression of lung cancer under smoking risk. For current smokers, our findings reveal that two to sixteen gene mutations are required to obtain a cancerous cell among men and women in US. Moreover, two to six (eleven) cancer-mutations are available in the pathway to lung cancer among former smokers who have quit smoking for more (less) than ten years for both male and female patients. This highlights that cigarette smoking stimulates the number of driver mutations during lung tumorigenesis in both sexes. It is very crucial to examine the role of cigarette smoking in determining whether genomic instability is an early stage or late stage in the process of lung carcinogenesis.
Collapse
|
3
|
Alvarado-Cruz I, Meas R, Paluri SLA, Carufe KEW, Khan M, Sweasy JB. The double-edged sword of cancer mutations: exploiting neoepitopes for the fight against cancer. Mutagenesis 2021; 35:69-78. [PMID: 31880305 DOI: 10.1093/mutage/gez049] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Accepted: 11/18/2019] [Indexed: 12/20/2022] Open
Abstract
Defects in DNA repair have been linked to the accumulation of somatic mutations in tumours. These mutations can promote oncogenesis; however, recent developments have indicated that they may also lead to a targeted immune response against the tumour. This response is initiated by the development of new antigenic epitopes (neoepitopes) arising from mutations in protein-coding genes that are processed and then presented on the surface of tumour cells. These neoepitopes are unique to the tumour, thus enabling lymphocytes to launch an immune response against the cancer cells. Immunotherapies, such as checkpoint inhibitors (CPIs) and tumour-derived vaccines, have been shown to enhance the immunogenic response to cancers and have led to complete remission in some cancer patients. There are tumours that are not responsive to immunotherapy or conventional tumour therapeutics; therefore, there is a push for new treatments to combat these unresponsive cancers. Recently, combinatorial treatments have been developed to further utilise the immune system in the fight against cancer. These treatments have the potential to exploit the defects in DNA repair by inducing more DNA damage and mutations. This can potentially lead to the expression of high levels of neoepitopes on the surface of tumour cells that will stimulate an immunological response. Overall, exploiting DNA repair defects in tumours may provide an edge in this long fight against cancer.
Collapse
Affiliation(s)
| | - Rithy Meas
- Department of Therapeutic Radiology, Yale University, New Haven, CT, USA
| | | | | | - Mohammed Khan
- Department of Cellular and Molecular Medicine, UA College of Medicine, Tucson, AZ, USA
| | | |
Collapse
|
4
|
Anagnostou M, Chung C, McGann E, Verheijen B, Kou Y, Chen L, Vermulst M. Transcription errors in aging and disease. TRANSLATIONAL MEDICINE OF AGING 2021. [DOI: 10.1016/j.tma.2021.05.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
|
5
|
Nagah A, Amer A, Zhang X. Mathematical modeling of female breast cancer in Japan. INT J BIOMATH 2020. [DOI: 10.1142/s1793524520500230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Cancer incidence rates are significantly different all over the world. Breast cancer is affected by many factors, the most important being genetics and lifestyle. The aim of this paper is to study the mutation mechanisms of breast cancer for Japanese women by fitting the incidence data of three high-quality population areas in Japan from 1985 to 2010. To achieve this goal, we have set up multi-stage models within the mathematical model of Moolgavkar, Venzon, and Knudson. Such models take both mutation rates and clonal expansion rates as parameters in each compartment into consideration. Based on our simulation outcomes, two to twelve driver mutations are sufficient in the pathway to female breast cancer in Japan. On the other hand, a previous study demonstrated that breast cancer in American women requires two to fourteen gene mutations to get a cancerous cell. Moreover, the 3-stage mathematical model is the optimal model as it fits clinical data very nicely for all affected cases of females in Japan and the US. The genetic instability has a prominent effect on the tumorigenesis of Japanese females caused by the first four driver mutations. The calculated results for Japanese women are compared with previous works for American women.
Collapse
Affiliation(s)
- Ahmed Nagah
- School of Mathematics and Statistics, Central China Normal, University, Wuhan 430079, P. R. China
- Mathematics Department, Faculty of Science, Zagazig University, Zagazig, Egypt
| | - Asmaa Amer
- School of Mathematics and Statistics, Central China Normal, University, Wuhan 430079, P. R. China
- Mathematics Department, Faculty of Science, Menoufia University, Egypt
| | - Xinan Zhang
- School of Mathematics and Statistics, Central China Normal, University, Wuhan 430079, P. R. China
| |
Collapse
|
6
|
Al-Hashimi F, J. Diaz-Cano S. Multi-target analysis of neoplasms for the evaluation of tumor progression: stochastic approach of biologic processes. AIMS MOLECULAR SCIENCE 2018. [DOI: 10.3934/molsci.2018.1.14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
|
7
|
Davis A, Gao R, Navin N. Tumor evolution: Linear, branching, neutral or punctuated? Biochim Biophys Acta Rev Cancer 2017; 1867:151-161. [PMID: 28110020 DOI: 10.1016/j.bbcan.2017.01.003] [Citation(s) in RCA: 211] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 01/14/2017] [Accepted: 01/16/2017] [Indexed: 02/08/2023]
Abstract
Intratumor heterogeneity has been widely reported in human cancers, but our knowledge of how this genetic diversity emerges over time remains limited. A central challenge in studying tumor evolution is the difficulty in collecting longitudinal samples from cancer patients. Consequently, most studies have inferred tumor evolution from single time-point samples, providing very indirect information. These data have led to several competing models of tumor evolution: linear, branching, neutral and punctuated. Each model makes different assumptions regarding the timing of mutations and selection of clones, and therefore has different implications for the diagnosis and therapeutic treatment of cancer patients. Furthermore, emerging evidence suggests that models may change during tumor progression or operate concurrently for different classes of mutations. Finally, we discuss data that supports the theory that most human tumors evolve from a single cell in the normal tissue. This article is part of a Special Issue entitled: Evolutionary principles - heterogeneity in cancer?, edited by Dr. Robert A. Gatenby.
Collapse
Affiliation(s)
- Alexander Davis
- Department of Genetics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA; Graduate School of Biomedical Sciences, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Ruli Gao
- Department of Genetics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Nicholas Navin
- Department of Genetics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA; Graduate School of Biomedical Sciences, The University of Texas MD Anderson Cancer Center, Houston, TX, USA; Department of Bioinformatics and Computational Biology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
| |
Collapse
|
8
|
Abstract
Cancer has challenged researchers with its immense complexity, from initiation to progression and on to therapeutic resistance. The seventh Origins of Cancer Symposium, held on July 22, 2016, at Van Andel Research Institute, was organized around the theme “Exploring Tumor Complexity”, and the latest advances under that theme from seven leading cancer research laboratories were discussed. Here we summarize highlights from the meeting and their implications.
Collapse
|
9
|
Abstract
Single-cell sequencing (SCS) is a powerful new tool for investigating evolution and diversity in cancer and understanding the role of rare cells in tumor progression. These methods have begun to unravel key questions in cancer biology that have been difficult to address with bulk tumor measurements. Over the past five years, there has been extraordinary progress in technological developments and research applications, but these efforts represent only the tip of the iceberg. In the coming years, SCS will greatly improve our understanding of invasion, metastasis, and therapy resistance during cancer progression. These tools will also have direct translational applications in the clinic, in areas such as early detection, noninvasive monitoring, and guiding targeted therapy. In this perspective, I discuss the progress that has been made and the myriad of unexplored applications that still lie ahead in cancer research and medicine.
Collapse
Affiliation(s)
- Nicholas E Navin
- Department of Genetics, University of Texas, MD Anderson Cancer Center, Houston, Texas 77030, USA; Department of Bioinformatics and Computational Biology, University of Texas, MD Anderson Cancer Center, Houston, Texas 77030, USA; Graduate Program in Genes and Development, Graduate School of Biomedical Sciences, University of Texas Health Science Center at Houston, Houston, Texas 77030, USA
| |
Collapse
|
10
|
Vermulst M, Denney AS, Lang MJ, Hung CW, Moore S, Moseley MA, Mosely AM, Thompson JW, Thompson WJ, Madden V, Gauer J, Wolfe KJ, Summers DW, Schleit J, Sutphin GL, Haroon S, Holczbauer A, Caine J, Jorgenson J, Cyr D, Kaeberlein M, Strathern JN, Duncan MC, Erie DA. Transcription errors induce proteotoxic stress and shorten cellular lifespan. Nat Commun 2015; 6:8065. [PMID: 26304740 DOI: 10.1038/ncomms9065] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 07/14/2015] [Indexed: 11/09/2022] Open
Abstract
Transcription errors occur in all living cells; however, it is unknown how these errors affect cellular health. To answer this question, we monitor yeast cells that are genetically engineered to display error-prone transcription. We discover that these cells suffer from a profound loss in proteostasis, which sensitizes them to the expression of genes that are associated with protein-folding diseases in humans; thus, transcription errors represent a new molecular mechanism by which cells can acquire disease phenotypes. We further find that the error rate of transcription increases as cells age, suggesting that transcription errors affect proteostasis particularly in aging cells. Accordingly, transcription errors accelerate the aggregation of a peptide that is implicated in Alzheimer's disease, and shorten the lifespan of cells. These experiments reveal a previously unappreciated role for transcriptional fidelity in cellular health and aging.
Collapse
Affiliation(s)
- Marc Vermulst
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599, USA.,Center for Mitochondrial and Epigenomic Medicine, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, USA
| | - Ashley S Denney
- School of Medicine, University of Colorado, Denver, Colorado 80217, USA
| | - Michael J Lang
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Chao-Wei Hung
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Stephanie Moore
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - M Arthur Moseley
- Proteomics Core Facility, Duke University, Durham, North Carolina 27710, USA
| | - Arthur M Mosely
- Proteomics Core Facility, Duke University, Durham, North Carolina 27710, USA
| | - J Will Thompson
- Proteomics Core Facility, Duke University, Durham, North Carolina 27710, USA
| | - William J Thompson
- Proteomics Core Facility, Duke University, Durham, North Carolina 27710, USA
| | - Victoria Madden
- Microscopy Services Laboratory, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Jacob Gauer
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Katie J Wolfe
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Daniel W Summers
- Department of Developmental Biology, and Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri 63110, USA
| | - Jennifer Schleit
- Department of Pathology, University of Washington, Seattle, Washington 98195, USA
| | - George L Sutphin
- Department of Pathology, University of Washington, Seattle, Washington 98195, USA
| | - Suraiya Haroon
- Center for Mitochondrial and Epigenomic Medicine, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, USA
| | - Agnes Holczbauer
- Center for Mitochondrial and Epigenomic Medicine, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, USA
| | - Joanne Caine
- CSIRO, Department of Materials Science and Engineering, Parkville 3052, Australia
| | - James Jorgenson
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Douglas Cyr
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Matt Kaeberlein
- Department of Pathology, University of Washington, Seattle, Washington 98195, USA
| | - Jeffrey N Strathern
- Center for Cancer Research, National Cancer Institute, Frederick, Maryland 21702, USA
| | - Mara C Duncan
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Dorothy A Erie
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599, USA.,Department of Chemistry, Curriculum in Applied Sciences and Engineering, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| |
Collapse
|
11
|
Simpson DA, Lemonie N, Morgan DS, Gaddameedhi S, Kaufmann WK. Oncogenic BRAF(V600E) Induces Clastogenesis and UVB Hypersensitivity. Cancers (Basel) 2015; 7:1072-90. [PMID: 26091525 PMCID: PMC4491700 DOI: 10.3390/cancers7020825] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Revised: 06/03/2015] [Accepted: 06/11/2015] [Indexed: 12/20/2022] Open
Abstract
The oncogenic BRAF(V600E) mutation is common in melanomas as well as moles. The roles that this mutation plays in the early events in the development of melanoma are poorly understood. This study demonstrates that expression of BRAF(V600E) is not only clastogenic, but synergizes for clastogenesis caused by exposure to ultraviolet radiation in the 300 to 320 nM (UVB) range. Expression of BRAF(V600E) was associated with induction of Chk1 pS280 and a reduction in chromatin remodeling factors BRG1 and BAF180. These alterations in the Chk1 signaling pathway and SWI/SNF chromatin remodeling pathway may contribute to the clastogenesis and UVB sensitivity. These results emphasize the importance of preventing sunburns in children with developing moles.
Collapse
Affiliation(s)
- Dennis A Simpson
- Department of Pathology & Laboratory Medicine, University of North Carolina at Chapel Hill, CB7295, Chapel Hill, NC 27599, USA.
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, CB7295, Chapel Hill, NC 27599, USA.
| | - Nathalay Lemonie
- Department of Pathology & Laboratory Medicine, University of North Carolina at Chapel Hill, CB7295, Chapel Hill, NC 27599, USA.
| | - David S Morgan
- Department of Pathology & Laboratory Medicine, University of North Carolina at Chapel Hill, CB7295, Chapel Hill, NC 27599, USA.
| | - Shobhan Gaddameedhi
- Department of Experimental and Systems Pharmacology, College of Pharmacy, Washington State University, Spokane, WA 99210, USA.
| | - William K Kaufmann
- Department of Pathology & Laboratory Medicine, University of North Carolina at Chapel Hill, CB7295, Chapel Hill, NC 27599, USA.
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, CB7295, Chapel Hill, NC 27599, USA.
- Center for Environmental Health and Susceptibility, University of North Carolina at Chapel Hill, CB7295, Chapel Hill, NC 27599, USA.
| |
Collapse
|
12
|
|
13
|
Diaz-Cano SJ. Pathological bases for a robust application of cancer molecular classification. Int J Mol Sci 2015; 16:8655-75. [PMID: 25898411 PMCID: PMC4425102 DOI: 10.3390/ijms16048655] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 04/07/2015] [Indexed: 12/12/2022] Open
Abstract
Any robust classification system depends on its purpose and must refer to accepted standards, its strength relying on predictive values and a careful consideration of known factors that can affect its reliability. In this context, a molecular classification of human cancer must refer to the current gold standard (histological classification) and try to improve it with key prognosticators for metastatic potential, staging and grading. Although organ-specific examples have been published based on proteomics, transcriptomics and genomics evaluations, the most popular approach uses gene expression analysis as a direct correlate of cellular differentiation, which represents the key feature of the histological classification. RNA is a labile molecule that varies significantly according with the preservation protocol, its transcription reflect the adaptation of the tumor cells to the microenvironment, it can be passed through mechanisms of intercellular transference of genetic information (exosomes), and it is exposed to epigenetic modifications. More robust classifications should be based on stable molecules, at the genetic level represented by DNA to improve reliability, and its analysis must deal with the concept of intratumoral heterogeneity, which is at the origin of tumor progression and is the byproduct of the selection process during the clonal expansion and progression of neoplasms. The simultaneous analysis of multiple DNA targets and next generation sequencing offer the best practical approach for an analytical genomic classification of tumors.
Collapse
Affiliation(s)
- Salvador J Diaz-Cano
- King's Health Partners, Cancer Studies, King's College Hospital-Viapath, Denmark Hill, London SE5-9RS, UK.
| |
Collapse
|
14
|
Huang S. Genetic and non-genetic instability in tumor progression: link between the fitness landscape and the epigenetic landscape of cancer cells. Cancer Metastasis Rev 2014; 32:423-48. [PMID: 23640024 DOI: 10.1007/s10555-013-9435-7] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Genetic instability is invoked in explaining the cell phenotype changes that take place during cancer progression. However, the coexistence of a vast diversity of distinct clones, most prominently visible in the form of non-clonal chromosomal aberrations, suggests that Darwinian selection of mutant cells is not operating at maximal efficacy. Conversely, non-genetic instability of cancer cells must also be considered. Such mutation-independent instability of cell states is most prosaically manifest in the phenotypic heterogeneity within clonal cell populations or in the reversible switching between immature "cancer stem cell-like" and more differentiated states. How are genetic and non-genetic instability related to each other? Here, we review basic theoretical foundations and offer a dynamical systems perspective in which cancer is the inevitable pathological manifestation of modes of malfunction that are immanent to the complex gene regulatory network of the genome. We explain in an accessible, qualitative, and permissively simplified manner the mathematical basis for the "epigenetic landscape" and how the latter relates to the better known "fitness landscape." We show that these two classical metaphors have a formal basis. By combining these two landscape concepts, we unite development and somatic evolution as the drivers of the relentless increase in malignancy. Herein, the cancer cells are pushed toward cancer attractors in the evolutionarily unused regions of the epigenetic landscape that encode more and more "dedifferentiated" states as a consequence of both genetic (mutagenic) and non-genetic (regulatory) perturbations-including therapy. This would explain why for the cancer cell, the principle of "What does not kill me makes me stronger" is as much a driving force in tumor progression and development of drug resistance as the simple principle of "survival of the fittest."
Collapse
Affiliation(s)
- Sui Huang
- Institute for Systems Biology, Seattle, WA, USA,
| |
Collapse
|
15
|
Abstract
The study of single cancer cells has transformed from qualitative microscopic images to quantitative genomic datasets. This paradigm shift has been fueled by the development of single-cell sequencing technologies, which provide a powerful new approach to study complex biological processes in human cancers.
Collapse
|
16
|
Huang Q, Suzuki M, Zeng Y, Zhang H, Yang D, Lin H. Downregulation of POLD4 in Calu6 cells results in G1-S blockage through suppression of the Akt-Skp2-p27 pathway. Bioorg Med Chem Lett 2014; 24:1780-3. [PMID: 24618301 DOI: 10.1016/j.bmcl.2014.02.033] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Revised: 01/27/2014] [Accepted: 02/11/2014] [Indexed: 12/23/2022]
Abstract
Previously, we have shown that downregulation of POLD4 in lung cancer cells delays progression through the G1-S cell cycle transition and leads to increased genomic instability. To date however, detailed molecular mechanisms have not been elucidated to explain how this occurs. In the present study, we found that reduction in POLD4 by siRNA knockdown promoted downregulation of both p-Akt Ser473 and Skp2 as well as upregulation of p27. Furthermore, these protein expression levels were rescued when siRNA-resistant POLD4 was ectopically expressed in the knockdown cells. These data suggest that the POLD4 downregulation is associated with impaired Akt-Skp2-p27 pathway in lung cancer.
Collapse
Affiliation(s)
- Qinmiao Huang
- Department of Pulmonary Medicine, Second Affiliated Hospital of Fujian Medical University, Fujian, China.
| | - Motoshi Suzuki
- Division of Molecular Carcinogenesis, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Yiming Zeng
- Department of Pulmonary Medicine, Second Affiliated Hospital of Fujian Medical University, Fujian, China
| | - Huaping Zhang
- Department of Pulmonary Medicine, Second Affiliated Hospital of Fujian Medical University, Fujian, China
| | - Dongyong Yang
- Department of Pulmonary Medicine, Second Affiliated Hospital of Fujian Medical University, Fujian, China
| | - Huihuang Lin
- Department of Pulmonary Medicine, Second Affiliated Hospital of Fujian Medical University, Fujian, China
| |
Collapse
|
17
|
Brooks PJ, Zakhari S. Moderate alcohol consumption and breast cancer in women: from epidemiology to mechanisms and interventions. Alcohol Clin Exp Res 2012; 37:23-30. [PMID: 23072454 DOI: 10.1111/j.1530-0277.2012.01888.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Accepted: 04/19/2012] [Indexed: 12/26/2022]
Abstract
Epidemiologic studies indicate that moderate alcohol consumption increases breast cancer risk in women. Understanding the mechanistic basis of this relationship has important implications for women's health and breast cancer prevention. In this commentary, we focus on some recent epidemiologic studies linking moderate alcohol consumption to breast cancer risk and place the results of those studies within the framework of our current understanding of the temporal and mechanistic basis of human carcinogenesis. This analysis supports the hypothesis that alcohol acts as a weak cumulative breast carcinogen and may also be a tumor promoter. We discuss the implications of these mechanisms for the prevention and treatment of alcohol-related breast cancer and present some considerations for future studies. Moderate alcohol consumption has been shown to benefit cardiovascular health and recently been associated with healthy aging. Therefore, a better understanding of how moderate alcohol consumption impacts breast cancer risk will allow women to make better informed decisions about the risks and benefits of alcohol consumption in the context of their overall health and at different stages of their life. Such mechanistic information is also important for the development of rational clinical interventions to reduce ethanol-related breast cancer mortality.
Collapse
Affiliation(s)
- Philip J Brooks
- Division of Metabolism and Health Effects, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD 20892-9304, USA.
| | | |
Collapse
|
18
|
Huang S. Tumor progression: Chance and necessity in Darwinian and Lamarckian somatic (mutationless) evolution. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2012; 110:69-86. [DOI: 10.1016/j.pbiomolbio.2012.05.001] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2012] [Revised: 04/29/2012] [Accepted: 05/02/2012] [Indexed: 02/05/2023]
|
19
|
Decreased mitochondrial DNA mutagenesis in human colorectal cancer. PLoS Genet 2012; 8:e1002689. [PMID: 22685414 PMCID: PMC3369930 DOI: 10.1371/journal.pgen.1002689] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Accepted: 03/20/2012] [Indexed: 01/05/2023] Open
Abstract
Genome instability is regarded as a hallmark of cancer. Human tumors frequently carry clonally expanded mutations in their mitochondrial DNA (mtDNA), some of which may drive cancer progression and metastasis. The high prevalence of clonal mutations in tumor mtDNA has commonly led to the assumption that the mitochondrial genome in cancer is genetically unstable, yet this hypothesis has not been experimentally tested. In this study, we directly measured the frequency of non-clonal (random) de novo single base substitutions in the mtDNA of human colorectal cancers. Remarkably, tumor tissue exhibited a decreased prevalence of these mutations relative to adjacent non-tumor tissue. The difference in mutation burden was attributable to a reduction in C:G to T:A transitions, which are associated with oxidative damage. We demonstrate that the lower random mutation frequency in tumor tissue was also coupled with a shift in glucose metabolism from oxidative phosphorylation to anaerobic glycolysis, as compared to non-neoplastic colon. Together these findings raise the intriguing possibility that fidelity of mitochondrial genome is, in fact, increased in cancer as a result of a decrease in reactive oxygen species-mediated mtDNA damage.
Collapse
|
20
|
Donigan KA, Hile SE, Eckert KA, Sweasy JB. The human gastric cancer-associated DNA polymerase β variant D160N is a mutator that induces cellular transformation. DNA Repair (Amst) 2012; 11:381-90. [PMID: 22341651 DOI: 10.1016/j.dnarep.2012.01.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Revised: 01/04/2012] [Accepted: 01/05/2012] [Indexed: 10/28/2022]
Abstract
Approximately 30% of human tumors sequenced to date harbor mutations in the POLB gene that are not present in matched normal tissue. Many mutations give rise to enzymes that contain non-synonymous single amino acid substitutions, several of which have been found to have aberrant activity or fidelity and transform cells when expressed. The DNA Polymerase β (Pol β) variant Asp160Asn (D160N) was first identified in a gastric tumor. Expression of D160N in cells induces cellular transformation as measured by hyperproliferation, focus formation, anchorage-independent growth and invasion. Here, we show that D160N is an active mutator polymerase that induces complex mutations. Our data support the interpretation that complex mutagenesis is the underlying mechanism of the observed cellular phenotypes, all of which are linked to tumorigenesis or tumor progression.
Collapse
Affiliation(s)
- Katherine A Donigan
- Department of Therapeutic Radiology, Yale School of Medicine, New Haven, CT 06520, United States
| | | | | | | |
Collapse
|
21
|
Diaz-Cano SJ. Tumor heterogeneity: mechanisms and bases for a reliable application of molecular marker design. Int J Mol Sci 2012; 13:1951-2011. [PMID: 22408433 PMCID: PMC3292002 DOI: 10.3390/ijms13021951] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Revised: 01/23/2012] [Accepted: 02/01/2012] [Indexed: 12/22/2022] Open
Abstract
Tumor heterogeneity is a confusing finding in the assessment of neoplasms, potentially resulting in inaccurate diagnostic, prognostic and predictive tests. This tumor heterogeneity is not always a random and unpredictable phenomenon, whose knowledge helps designing better tests. The biologic reasons for this intratumoral heterogeneity would then be important to understand both the natural history of neoplasms and the selection of test samples for reliable analysis. The main factors contributing to intratumoral heterogeneity inducing gene abnormalities or modifying its expression include: the gradient ischemic level within neoplasms, the action of tumor microenvironment (bidirectional interaction between tumor cells and stroma), mechanisms of intercellular transference of genetic information (exosomes), and differential mechanisms of sequence-independent modifications of genetic material and proteins. The intratumoral heterogeneity is at the origin of tumor progression and it is also the byproduct of the selection process during progression. Any analysis of heterogeneity mechanisms must be integrated within the process of segregation of genetic changes in tumor cells during the clonal expansion and progression of neoplasms. The evaluation of these mechanisms must also consider the redundancy and pleiotropism of molecular pathways, for which appropriate surrogate markers would support the presence or not of heterogeneous genetics and the main mechanisms responsible. This knowledge would constitute a solid scientific background for future therapeutic planning.
Collapse
Affiliation(s)
- Salvador J. Diaz-Cano
- Department Histopathology, King’s College Hospital and King’s Health Partners, Denmark Hill, London SE5 9RS, UK; E-Mail: ; Tel.: +44-20-3299-3041; Fax: +44-20-3299-3670
| |
Collapse
|
22
|
Linos K, Slominski A, Ross JS, Carlson JA. Melanoma update: diagnostic and prognostic factors that can effectively shape and personalize management. Biomark Med 2011; 5:333-60. [PMID: 21657842 DOI: 10.2217/bmm.11.39] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Routine light microscopy remains a powerful tool to diagnose, stage and prognose melanoma. Although it is very economical and efficient, it requires a significant level of expertise and, in difficult cases the final diagnosis is affected by subjective interpretation. Fortunately, new insights into the genomic aberrations characteristic of melanoma, coupled with ancillary studies, are further refining evaluation and management allowing for more confident diagnosis, more accurate staging and the selection of targeted therapy. In this article, we review the standard of care and new updates including four probe FISH, the 2009 American Joint Commission on Cancer staging of melanoma and mutant testing of melanoma, which will be crucial for targeted therapy of metastatic melanoma.
Collapse
|
23
|
Parsons BL, Myers MB, Meng F, Wang Y, McKinzie PB. Oncomutations as biomarkers of cancer risk. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2010; 51:836-850. [PMID: 20740637 DOI: 10.1002/em.20600] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Cancer risk assessment impacts a range of societal needs, from the regulation of chemicals to achieving the best possible human health outcomes. Because oncogene and tumor suppressor gene mutations are necessary for the development of cancer, such mutations are ideal biomarkers to use in cancer risk assessment. Consequently, DNA-based methods to quantify particular tumor-associated hotspot point mutations (i.e., oncomutations) have been developed, including allele-specific competitive blocker-PCR (ACB-PCR). Several studies using ACB-PCR and model mutagens have demonstrated that significant induction of tumor-associated oncomutations are measureable at earlier time points than are used to score tumors in a bioassay. In the particular case of benzo[a]pyrene induction of K-Ras codon 12 TGT mutation in the A/J mouse lung, measurement of tumor-associated oncomutation was shown to be an earlier and more sensitive endpoint than tumor response. The measurement of oncomutation by ACB-PCR led to two unexpected findings. First, oncomutations are present in various tissues of control rodents and "normal" human colonic mucosa samples at relatively high frequencies. Approximately 60% of such samples (88/146) have mutant fractions (MFs) >10(-5), and some have MFs as high as 10(-3) or 10(-4). Second, preliminary data indicate that oncomutations are present frequently as subpopulations in tumors. These findings are integrated into a hypothesis that the predominant preexisting mutations in particular tissues may be useful as generic reporters of carcinogenesis. Future research opportunities using oncomutation as an endpoint are described, including rodent to human extrapolation, dose-response assessment, and personalized medicine.
Collapse
Affiliation(s)
- Barbara L Parsons
- Division of Genetic and Reproductive Toxicology, National Center for Toxicological Research, Jefferson, Arkansas 72079, USA.
| | | | | | | | | |
Collapse
|
24
|
Genomic instability at both the base pair level and the chromosomal level is detectable in earliest PanIN lesions in tissues of chronic pancreatitis. Pancreas 2010; 39:1093-103. [PMID: 20531246 DOI: 10.1097/mpa.0b013e3181dc62f6] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
OBJECTIVE Chronic pancreatitis (CP) is a predisposing disease for pancreatic carcinoma (PC), however, precise molecular mechanisms of cancer development in the background of CP are ill defined. METHODS A total of 443 laser-microdissected pancreatic intraepithelial neoplasias (PanINs), acinar-ductal metaplasia (ADM), and normal ducts from 21 patients with CP were analyzed for loss of heterozygosity (LOH) and immunohistochemical protein expression of p53, p16, and DPC4. Pancreatic intraepithelial neoplasias were analyzed for mutations in p53, p16, and Ki-ras genes by ABI sequencing. Aneuploidy was determined by fluorescence in situ hybridization with probes for chromosomes 3, 7, 8, and 17. RESULTS Loss of heterozygosity rate in PanIN-1 and ADM was between 1.7% (p53) and 5.8% (p16). In PanIN-3, p53 protein overexpression and loss of expression for p16 and DPC4 protein were seen. Heterozygous mutations of p53 and p16 without LOH were found in PanIN-1A and ADM, whereas homozygous mutations were found in PanIN-3. Aneuploidy increased from PanIN-1A to PanIN-3. Ki-ras mutations were discovered first in PanIN-1. CONCLUSIONS Heterozygous mutations of p53- and p16 genes together with chromosomal instability occur early in CP and are clonally expanded, but final inactivation mostly by LOH happens later in pancreatic carcinogenesis. Determination of aneuploidy in pancreatic juice may be of value for early detection and risk assessment in patients with long-standing CP.
Collapse
|
25
|
Huang QM, Tomida S, Masuda Y, Arima C, Cao K, Kasahara TA, Osada H, Yatabe Y, Akashi T, Kamiya K, Takahashi T, Suzuki M. Regulation of DNA polymerase POLD4 influences genomic instability in lung cancer. Cancer Res 2010; 70:8407-16. [PMID: 20861182 DOI: 10.1158/0008-5472.can-10-0784] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Genomic instability is an important factor in cancer susceptibility, but a mechanistic understanding of how it arises remains unclear. We examined hypothesized contributions of the replicative DNA polymerase δ (pol δ) subunit POLD4 to the generation of genomic instability in lung cancer. In examinations of 158 lung cancers and 5 mixtures of 10 normal lungs, cell cycle- and checkpoint-related genes generally showed mRNA expression increases in cancer, whereas POLD4 showed reduced mRNA in small cell lung cancer (SCLC). A fraction of non-small cell lung cancer patients also showed low expression comparable with that in SCLC, which was associated with poor prognosis. The lung cancer cell line ACC-LC-48 was found to have low POLD4 expression, with higher histone H3K9 methylation and lower acetylation in the POLD4 promoter, as compared with the A549 cell line with high POLD4 expression. In the absence of POLD4, pol δ exhibited impaired in vitro DNA synthesis activity. Augmenting POLD4 expression in cells where it was attenuated altered the sensitivity to the chemical carcinogen 4-nitroquinoline-1-oxide. Conversely, siRNA-mediated reduction of POLD4 in cells with abundant expression resulted in a cell cycle delay, checkpoint activation, and an elevated frequency of chromosomal gap/break formation. Overexpression of an engineered POLD4 carrying silent mutations at the siRNA target site rescued these phenotypes, firmly establishing the role of POLD4 in these effects. Furthermore, POLD4 overexpression reduced intrinsically high induction of γ-H2AX, a well-accepted marker of double-stranded DNA breaks. Together, our findings suggest that reduced expression of POLD4 plays a role in genomic instability in lung cancer.
Collapse
Affiliation(s)
- Qin Miao Huang
- Division of Molecular Carcinogenesis, Nagoya University Graduate School of Medicine, Aichi Cancer Center Research Institute, Nagoya, Japan
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
26
|
Krutyakov VM, Kravetskaya TP. DNA polymerases and carcinogenesis. BIOCHEMISTRY (MOSCOW) 2010; 75:959-64. [DOI: 10.1134/s000629791008002x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
27
|
Abstract
Defining the pathways through which tumors progress is critical to our understanding and treatment of cancer. We do not routinely sample patients at multiple time points during the progression of their disease, and thus our research is limited to inferring progression a posteriori from the examination of a single tumor sample. Despite this limitation, inferring progression is possible because the tumor genome contains a natural history of the mutations that occur during the formation of the tumor mass. There are two approaches to reconstructing a lineage of progression: (1) inter-tumor comparisons, and (2) intra-tumor comparisons. The inter-tumor approach consists of taking single samples from large collections of tumors and comparing the complexity of the genomes to identify early and late mutations. The intra-tumor approach involves taking multiple samples from individual heterogeneous tumors to compare divergent clones and reconstruct a phylogenetic lineage. Here we discuss how these approaches can be used to interpret the current models for tumor progression. We also compare data from primary and metastatic copy number profiles to shed light on the final steps of breast cancer progression. Finally, we discuss how recent technical advances in single cell genomics will herald a new era in understanding the fundamental basis of tumor heterogeneity and progression.
Collapse
Affiliation(s)
- Nicholas E Navin
- Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA.
| | | |
Collapse
|
28
|
Davis BR, Yan Q, Bui JH, Felix K, Moratto D, Muul LM, Prokopishyn NL, Blaese RM, Candotti F. Somatic mosaicism in the Wiskott–Aldrich syndrome: Molecular and functional characterization of genotypic revertants. Clin Immunol 2010; 135:72-83. [DOI: 10.1016/j.clim.2009.12.011] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2009] [Revised: 12/18/2009] [Accepted: 12/21/2009] [Indexed: 12/22/2022]
|
29
|
Mastrocola AS, Heinen CD. Nuclear reorganization of DNA mismatch repair proteins in response to DNA damage. DNA Repair (Amst) 2010; 9:120-33. [PMID: 20004149 PMCID: PMC2819642 DOI: 10.1016/j.dnarep.2009.11.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2009] [Revised: 10/16/2009] [Accepted: 11/04/2009] [Indexed: 12/16/2022]
Abstract
The DNA mismatch repair (MMR) system is highly conserved and vital for preserving genomic integrity. Current mechanistic models for MMR are mainly derived from in vitro assays including reconstitution of strand-specific MMR and DNA binding assays using short oligonucleotides. However, fundamental questions regarding the mechanism and regulation in the context of cellular DNA replication remain. Using synchronized populations of HeLa cells we demonstrated that hMSH2, hMLH1 and PCNA localize to the chromatin during S-phase, and accumulate to a greater extent in cells treated with a DNA alkylating agent. In addition, using small interfering RNA to deplete hMSH2, we demonstrated that hMLH1 localization to the chromatin is hMSH2-dependent. hMSH2/hMLH1/PCNA proteins, when associated with the chromatin, form a complex that is greatly enhanced by DNA damage. The DNA damage caused by high doses of alkylating agents leads to a G(2) arrest after only one round of replication. In these G(2)-arrested cells, an hMSH2/hMLH1 complex persists on chromatin, however, PCNA is no longer in the complex. Cells treated with a lower dose of alkylating agent require two rounds of replication before cells arrest in G(2). In the first S-phase, the MMR proteins form a complex with PCNA, however, during the second S-phase PCNA is missing from that complex. The distinction between these complexes may suggest separate functions for the MMR proteins in damage repair and signaling. Additionally, using confocal immunofluorescence, we observed a population of hMSH6 that localized to the nucleolus. This population is significantly reduced after DNA damage suggesting that the protein is shuttled out of the nucleolus in response to damage. In contrast, hMLH1 is excluded from the nucleolus at all times. Thus, the nucleolus may act to segregate a population of hMSH2-hMSH6 from hMLH1-hPMS2 such that, in the absence of DNA damage, an inappropriate response is not invoked.
Collapse
Affiliation(s)
- Adam S. Mastrocola
- Neag Comprehensive Cancer Center and Center for Molecular Medicine, University of Connecticut Health Center, Farmington, Connecticut 06030, USA
| | - Christopher D. Heinen
- Neag Comprehensive Cancer Center and Center for Molecular Medicine, University of Connecticut Health Center, Farmington, Connecticut 06030, USA
| |
Collapse
|
30
|
Polyploidy: Mechanisms and Cancer Promotion in Hematopoietic and Other Cells. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 676:105-22. [DOI: 10.1007/978-1-4419-6199-0_7] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
31
|
Kensler TW, Groopman JD. Is it time to advance the chemoprevention of environmental carcinogenesis with microdosing trials? Cancer Prev Res (Phila) 2009; 2:1003-7. [PMID: 19952364 DOI: 10.1158/1940-6207.capr-09-0232] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
This perspective on Jubert et al. (beginning on page [1015] in this issue of the journal) discusses the use of microdosing with environmental carcinogens to accelerate the evaluation and optimization of chemopreventive interventions. The need for chemoprevention of environmental carcinogenesis is considered, as are the structure of microdosing, or phase 0, trials, technologies required to conduct microdose studies in this context, and ethical concerns. We also reflect on what microdosing studies have taught us to date.
Collapse
Affiliation(s)
- Thomas W Kensler
- Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore, MD 21205, USA.
| | | |
Collapse
|
32
|
Shen C, Zhou Y, Zhan J, Reske SN, Buck AK. Chromosome instability and tumor lethality suppression in carcinogenesis. J Cell Biochem 2008; 105:1327-41. [DOI: 10.1002/jcb.21937] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
33
|
Chen Z, Feng J, Buzin CH, Sommer SS. Epidemiology of doublet/multiplet mutations in lung cancers: evidence that a subset arises by chronocoordinate events. PLoS One 2008; 3:e3714. [PMID: 19005564 PMCID: PMC2579325 DOI: 10.1371/journal.pone.0003714] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2008] [Accepted: 10/10/2008] [Indexed: 01/01/2023] Open
Abstract
Background Evidence strongly suggests that spontaneous doublet mutations in normal mouse tissues generally arise from chronocoordinate events. These chronocoordinate mutations sometimes reflect “mutation showers”, which are multiple chronocoordinate mutations spanning many kilobases. However, little is known about mutagenesis of doublet and multiplet mutations (domuplets) in human cancer. Lung cancer accounts for about 25% of all cancer deaths. Herein, we analyze the epidemiology of domuplets in the EGFR and TP53 genes in lung cancer. The EGFR gene is an oncogene in which doublets are generally driver plus driver mutations, while the TP53 gene is a tumor suppressor gene with a more typical situation in which doublets derive from a driver and passenger mutation. Methodology/Principal Findings EGFR mutations identified by sequencing were collected from 66 published papers and our updated EGFR mutation database (www.egfr.org). TP53 mutations were collected from IARC version 12 (www-p53.iarc.fr). For EGFR and TP53 doublets, no clearly significant differences in race, ethnicity, gender and smoking status were observed. Doublets in the EGFR and TP53 genes in human lung cancer are elevated about eight- and three-fold, respectively, relative to spontaneous doublets in mouse (6% and 2.3% versus 0.7%). Conclusions/Significance Although no one characteristic is definitive, the aggregate properties of doublet and multiplet mutations in lung cancer are consistent with a subset derived from chronocoordinate events in the EGFR gene: i) the eight frameshift doublets (present in 0.5% of all patients with EGFR mutations) are clustered and produce a net in-frame change; ii) about 32% of doublets are very closely spaced (≤30 nt); and iii) multiplets contain two or more closely spaced mutations. TP53 mutations in lung cancer are very closely spaced (≤30 nt) in 33% of doublets, and multiplets generally contain two or more very closely spaced mutations. Work in model systems is necessary to confirm the significance of chronocoordinate events in lung and other cancers.
Collapse
Affiliation(s)
- Zhenbin Chen
- Department of Molecular Genetics, City of Hope National Medical Center, Duarte, California, United States of America
| | - Jinong Feng
- Department of Molecular Genetics, City of Hope National Medical Center, Duarte, California, United States of America
| | - Carolyn H. Buzin
- Department of Molecular Genetics, City of Hope National Medical Center, Duarte, California, United States of America
| | - Steve S. Sommer
- Department of Molecular Genetics, City of Hope National Medical Center, Duarte, California, United States of America
- * E-mail:
| |
Collapse
|
34
|
Méndez-Gómez J, García-Vargas GG, López-Carrillo L, Calderón-Aranda ES, Gómez A, Vera E, Valverde M, Cebrián ME, Rojas E. Genotoxic Effects of Environmental Exposure to Arsenic and Lead on Children in Region Lagunera, Mexico. Ann N Y Acad Sci 2008; 1140:358-67. [DOI: 10.1196/annals.1454.027] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
|
35
|
Human T-cell leukemia virus type 1 tax attenuates the ATM-mediated cellular DNA damage response. J Virol 2008; 82:6952-61. [PMID: 18434398 DOI: 10.1128/jvi.02331-07] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Genomic instability, a hallmark of leukemic cells, is associated with malfunctioning cellular responses to DNA damage caused by defective cell cycle checkpoints and/or DNA repair. Adult T-cell leukemia, which can result from infection with human T-cell leukemia virus type 1 (HTLV-1), is associated with extensive genomic instability that has been attributed to the viral oncoprotein Tax. How Tax influences cellular responses to DNA damage to mediate genomic instability, however, remains unclear. Therefore, we investigated the effect of Tax on cellular pathways involved in recognition and repair of DNA double-strand breaks. Premature attenuation of ATM kinase activity and reduced association of MDC1 with repair foci were observed in Tax-expressing cells. Following ionizing radiation-induced S-phase checkpoint activation, Tax-expressing cells progressed more rapidly than non-Tax-expressing cells toward DNA replication. These results demonstrate that Tax expression may allow premature DNA replication in the presence of genomic lesions. Attempts to replicate in the presence of these lesions would result in gradual accumulation of mutations, leading to genome instability and cellular transformation.
Collapse
|
36
|
Laconi E, Doratiotto S, Vineis P. The microenvironments of multistage carcinogenesis. Semin Cancer Biol 2008; 18:322-9. [PMID: 18456510 DOI: 10.1016/j.semcancer.2008.03.019] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2008] [Accepted: 03/25/2008] [Indexed: 12/19/2022]
Abstract
Overt neoplasia is often the result of a chronic disease process encompassing an extended segment of the lifespan of any species. A common pathway in the natural history of the disease is the appearance of focal proliferative lesions that are known to act as precursors for cancer development. It is becoming increasingly apparent that the emergence of such lesions is not a cell-autonomous phenomenon, but is heavily dependent on microenvironmental cues derived from the surrounding tissue. Specific alterations in the tissue microenvironment that can foster the selective growth of focal lesions are discussed herein. Furthermore, we argue that a fundamental property of focal lesions as it relates to their precancerous nature lies in their altered growth pattern as compared to the tissue where they reside. The resulting altered tissue architecture translates into the emergence of a unique tumor microenvironment inside these lesions, associated with altered blood vessels and/or blood supply which in turn can trigger biochemical and metabolic changes fueling tumor progression. A deeper understanding of the role(s) of tissue and tumor microenvironments in the pathogenesis of cancer is essential to design more effective strategies for the management of this disease.
Collapse
Affiliation(s)
- Ezio Laconi
- Dipartimento di Scienze e Tecnologie Biomediche, Sezione di Patologia Sperimentale, Università di Cagliari, 09125 Cagliari, Italy.
| | | | | |
Collapse
|
37
|
Abstract
Cancer stem cells have been variously defined as cells within a cancer that have the exclusive ability to self-renew and to differentiate into the heterogeneous lineages of cancer cells that comprise the tumor. Interest in cancer stem cells is currently high, arising from recent reports identifying cell surface markers that can be used to sort such cells from primary human tumors. However, use of the term cancer stem cell may be misleading. A better term might be cancer-initiating cells because it remains to be demonstrated that cancer stem cells have the properties that define normal stem cells, including multipotency and the ability to undergo asymmetric and symmetric divisions. Many properties of cancer stem cells remain unclear, particularly the stability of their phenotype. These uncertainties must be considered in the development and testing of compounds targeted against putative cancer stem cells. Tumors apparently contain very few cancer stem cells, so that when tests of compounds targeted to such cells are designed, short-term response trials may not be informative and long-term trials must be planned, particularly if the drugs could also kill normal stem cells.
Collapse
Affiliation(s)
- Richard P Hill
- Ontario Cancer Institute/Princess Margaret Hospital, University Health Network, and Department of Medical Biophysics, University of Toronto, 610 University Ave, Toronto, Canada M5G2M9.
| | | |
Collapse
|
38
|
Vickers MA. JAK2 617V>F–positive polycythemia rubra vera maintained by approximately 18 stochastic stem-cell divisions per year, explaining age of onset by a single rate-limiting mutation. Blood 2007; 110:1675-80. [PMID: 17452518 DOI: 10.1182/blood-2006-12-061911] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
AbstractAs the rates of most cancers are proportional to the fourth to fifth power of age (“log-log” behavior), it is widely believed that 5 to 6 independent mutations are necessary for malignant transformation. Conversely, the peak incidences of most cancers are similar to stem-cell mutation rates at single loci, implying only one rate-limiting mutation. Here, flow cytometrically measured red blood cells mutated at a selectively neutral locus, glycophorin A, allow observation of individual stem-cell differentiation events in a log-log malignancy, polycythemia rubra vera. Contrary to predictions from multistep models, the clone is driven by infrequent (< annual) and rare (∼ 18 per year) differentiation events. These parameters imply that malignant stem cells have a modest selective advantage. Correspondingly minor, typically less than 20%, increases in stochastic self-renewal ratios are modeled to show that single mutations can result in the observed fourth power relationship with age. The conundrum between log-log behavior and mutation rate is thereby reconcilable, with the age of onset arising not from the requirement for multiple, independent mutations but from infrequent, stochastic stem-cell division rates and single mutations causing initially minor effects, but initiating a clone whose expected number increases successively with age—an “exponential phenotype.”
Collapse
Affiliation(s)
- Mark A Vickers
- Department of Medicine and Therapeutics, Aberdeen University Medical School, Aberdeen, United Kingdom.
| |
Collapse
|
39
|
Huang CS, Shen CY, Wang HW, Wu PE, Cheng CW. Increased expression of SRp40 affecting CD44 splicing is associated with the clinical outcome of lymph node metastasis in human breast cancer. Clin Chim Acta 2007; 384:69-74. [PMID: 17651715 DOI: 10.1016/j.cca.2007.06.001] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2007] [Revised: 06/06/2007] [Accepted: 06/06/2007] [Indexed: 12/26/2022]
Abstract
BACKGROUND During the malignant transformation of breast tissues, the pre-mRNA precursor splicing of specific genes can be flexibly regulated, leading to the formation of different forms or amounts of mRNA in response to the cellular microenvironment, and is frequently associated with cell tumorigenesis and may even cause tumor metastasis. Regulation of pre-mRNA splicing by serine-arginine (SR)-rich phosphoprotein is hypothesized to be associated with tumor cell metastasis. METHODS We enrolled 55 breast cancer patients (32 with lymph node metastasis; LNM) with paired tissue samples consisting of cancerous and tumor-adjacent normal portions and assayed these tissues for gene expression of the SR family using quantitative real-time RT-PCR (qRT-PCR), then evaluated an association with LNM of breast cancer. Furthermore, we examined whether increased expression of a specific SR gene was associated with the presence of specific CD44 spliced variants using qualitative reverse-transcription PCR (RT-PCR). RESULTS Support for our hypothesis came from the observations that breast tumor tissues displayed higher level of SRp40 expression as compared with the paired non-cancerous tissues, which manifested the significant association between increased SRp40 expression and LNM (OR=4.48, 95% CI, 1.08-19.50, P=0.018). In addition, the primary tumors of breast with increased expression of SRp40 gene were associated with the presence of the large CD44 inclusion variants, CD44v2, CD44v3, CD44v5, and CD44v6 (P<0.05). CONCLUSION Increased expression of SRp40 can be detected in breast tumor tissues with a high degree of sensitivity, and that higher expression of SRp40 closely correlates with alternative pre-mRNA splicing of CD44, which may serve as an earlier marker in predicting the risk to breast cancer patients of developing LNM.
Collapse
Affiliation(s)
- Chiun-Sheng Huang
- Department of Surgery, National Taiwan University Hospital, Taipei, Taiwan
| | | | | | | | | |
Collapse
|
40
|
Tapp RA, Feng J, Jones JW, Carlson JA, Wilson VL. Single base instability is promoted in vulvar lichen sclerosus. J Invest Dermatol 2007; 127:2563-76. [PMID: 17554370 DOI: 10.1038/sj.jid.5700889] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Single base substitution mutations in codons 248 and 273 of TP53 and codon 12 Kirsten-ras (KRAS) are commonly found in human carcinomas. To determine whether these mutations also occur in normal and inflamed tissues from which carcinomas arise, we utilized the ultra-sensitive polymerase chain reaction/restriction endonuclease/ligase chain reaction mutation assay. Ninety samples of genital skin, including lichen sclerosus (LS) affected skin, adjacent normal and non-adjacent normal, were assayed. Mutations were detected in 103 of 349 assays and consisted of KRAS G34A, G34T, G35A, and TP53 C742T, G818C, C817T, and G818A mutations. Mutant prevalence varied from 1 to 20 per 10(6) wild-type cells. Mutations occurred significantly more frequently in LS (78/224 (35%)) than adjacent normal (20/88 (23%)) and non-adjacent normal genital skin (5/38 (13%)). KRAS G34A mutation was relatively common to all classes of specimen, whereas TP53 gene C742T and G818C mutations were significantly more frequent in LS than normal genital skin. In matched samples, immunohistochemistry evaluation of p53 protein expression revealed the presence of epidermal p53 clones in LS whose presence and number significantly correlated with the presence of TP53 C742T and G818C mutations. Based on these results, it appears oncogenic point mutations occur in normal genital skin, and are selected for in LS.
Collapse
Affiliation(s)
- Ronald A Tapp
- Department of Veterinary Comparative Biomedical Sciences, Louisiana State University, Baton Rouge, Louisiana, USA
| | | | | | | | | |
Collapse
|
41
|
Lang T, Dalal S, Chikova A, DiMaio D, Sweasy JB. The E295K DNA polymerase beta gastric cancer-associated variant interferes with base excision repair and induces cellular transformation. Mol Cell Biol 2007; 27:5587-96. [PMID: 17526740 PMCID: PMC1952088 DOI: 10.1128/mcb.01883-06] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Approximately 30% of human tumors examined for mutations in polymerase beta (pol beta) appear to express pol beta variant proteins (D. Starcevic, S. Dalal, and J. B. Sweasy, Cell Cycle 3:998-1001, 2004). Many of these variants result from a single amino acid substitution. We have previously shown that the K289M and I260M colon and prostate cancer variants, respectively, induce cellular transformation most likely due to sequence-specific mutator activity (S. Dalal et al., Biochemistry 44:15664-15673, 2005; T. Lang et al., Proc. Natl. Acad. Sci. USA 101:6074-6079, 2004; J. B. Sweasy et al., Proc. Natl. Acad. Sci. USA 102:14350-14355, 2005). In the work described here, we show that the E295K gastric carcinoma pol beta variant acts in a dominant-negative manner by interfering with base excision repair. This leads to an increase in sister chromatid exchanges. Expression of the E295K variant also induces cellular transformation. Our data suggest that unfilled gaps are channeled into a homology-directed repair pathway that could lead to genomic instability. The results indicate that base excision repair is critical for maintaining genome stability and could therefore be a tumor suppressor mechanism.
Collapse
Affiliation(s)
- Tieming Lang
- Department of Therapeutic Radiology, Yale University School of Medicine, 15 York Street, P.O. Box 20840, New Haven, CT 06520, USA
| | | | | | | | | |
Collapse
|
42
|
Bielas JH, Venkatesan RN, Loeb LA. LOH-proficient embryonic stem cells: a model of cancer progenitor cells? Trends Genet 2007; 23:154-7. [PMID: 17328987 DOI: 10.1016/j.tig.2007.02.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2006] [Revised: 12/07/2006] [Accepted: 02/13/2007] [Indexed: 11/15/2022]
Abstract
Cancers are thought to originate in stem cells through the accumulation of multiple mutations. Some of these mutations result in a loss of heterozygosity (LOH). A recent report demonstrates that exposure of mouse embryonic stem cells to nontoxic amounts of mutagens triggers a marked increase in the frequency of LOH. Thus, mutagen induction of LOH in embryonic stem cells suggests a new pathway to account for the multiple homozygous mutations in human tumors. This induction could mimic early mutagenic events that generate cancers in human tissue stem cells.
Collapse
Affiliation(s)
- Jason H Bielas
- Gottstein Memorial Cancer Research Laboratory, Department of Pathology, University of Washington School of Medicine, Seattle, WA 98195-7705, USA
| | | | | |
Collapse
|
43
|
Bacher JM, Schimmel P. An editing-defective aminoacyl-tRNA synthetase is mutagenic in aging bacteria via the SOS response. Proc Natl Acad Sci U S A 2007; 104:1907-12. [PMID: 17264207 PMCID: PMC1794292 DOI: 10.1073/pnas.0610835104] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Mistranslation in bacterial and mammalian cells leads to production of statistical proteins that are, in turn, associated with specific cell or animal pathologies, including death of bacterial cells, apoptosis of mammalian cells in culture, and neurodegeneration in the mouse. A major source of mistranslation comes from heritable defects in the editing activities of aminoacyl-tRNA synthetases. These activities clear errors of aminoacylation by deacylation of mischarged tRNAs. We hypothesized that, in addition to previously reported phenotypes in bacterial and mammalian systems, errors of aminoacylation could be mutagenic and lead to disease. As a first step in testing this hypothesis, the effect of an editing defect in a single tRNA synthetase on the accumulation of mutations in aging bacteria was investigated. A striking, statistically significant, enhancement of the mutation rate in aging bacteria was found. This enhancement comes from an increase in error-prone DNA repair through induction of the bacterial SOS response. Thus, mistranslation, as caused by an editing-defective tRNA synthetase, can lead to heritable genetic changes that could, in principle, be linked to disease.
Collapse
Affiliation(s)
- Jamie M. Bacher
- The Skaggs Institute for Chemical Biology, and Departments of Molecular Biology and Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, BCC-379, La Jolla, CA 92037
| | - Paul Schimmel
- The Skaggs Institute for Chemical Biology, and Departments of Molecular Biology and Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, BCC-379, La Jolla, CA 92037
- *To whom correspondence should be addressed. E-mail:
| |
Collapse
|
44
|
Nguyen HG, Ravid K. Tetraploidy/aneuploidy and stem cells in cancer promotion: The role of chromosome passenger proteins. J Cell Physiol 2006; 208:12-22. [PMID: 16331679 DOI: 10.1002/jcp.20565] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
While polyploidy, a state of having fully duplicated sets of chromosomes per cell, has been described in normally developing bone marrow megakaryocytes or as an adaptive response in other cell types, aneuploidy is never detected in normal cells. Tetraploidy or aneuploidy can be induced by several signals and it is highly prevalent in different forms of cancers, suggesting a role for this cell cycle state in promoting cellular transformation. Investigations suggested that loss of heterozygosity of cancer-related genes in stem cells might contribute to genetic instability in progeny cells and to subsequent cancer development. Deregulated expression of chromosome passenger proteins, such as Aurora kinases or Survivin, is a hallmark of various cancers, and experimentally induced changes in these regulators can promote tetraploidy or aneuploidy and loss of heterozygosity. Our studies described an induction of tetraploidy/aneuploidy by a stable form of Aurora-B, leading to acquisition of transformation properties. It is intriguing to speculate that in some cancers, tetraploidy/aneuploidy induced by deregulated expression of a mitotic regulator represents a primary event that leads to unbalanced expression of a cluster of crucial genes and to cellular transformation.
Collapse
Affiliation(s)
- Hao G Nguyen
- Department of Biochemistry and Medicine, Cancer Center, Boston University School of Medicine, Boston, Massachusetts, USA
| | | |
Collapse
|
45
|
Masramon L, Vendrell E, Tarafa G, Capellà G, Miró R, Ribas M, Peinado MA. Genetic instability and divergence of clonal populations in colon cancer cells in vitro. J Cell Sci 2006; 119:1477-82. [PMID: 16551697 DOI: 10.1242/jcs.02871] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The accumulation of multiple chromosomal abnormalities is a characteristic of the majority of colorectal cancers and has been attributed to an underlying chromosomal instability. Genetic instability is considered to have a key role in the generation of genetic and phenotypic heterogeneity in cancer cells. To shed light on the dynamics of chromosomal instability in colon cancer cells, we have analyzed genetic divergence in clonal and subclonal derivates of chromosomally unstable (SW480) and stable (HCT116, LoVo) cell lines. Conventional G-banding karyotyping and arbitrarily primed PCR (AP-PCR) fingerprinting were used to calculate genetic distances among clones and parental cells, and to trace tree-type phylogenies among individual cells and clonal cell populations. SW480 cells showed enhanced karyotypic heterogeneity in clones as compared with parental cells. Moreover, genetic clonal divergence was also increased after two consecutive episodes of single-cell cloning, demonstrating that the homogeneity induced by the bottleneck of cloning is disrupted by genetic instability during clonal expansion and, as a consequence, heterogeneity is restored. These results demonstrate genetic drift in clonal populations originated from isolated cells. The generated cell heterogeneity coupled with selection provides the grounds for the reported feasibility of pre-neoplastic and neoplastic cells to generate new phenotypic variants with increased evolutionary potential.
Collapse
Affiliation(s)
- Laia Masramon
- IDIBELL-Institut de Recerca Oncològica, L'Hospitalet, 08907 Barcelona, Spain
| | | | | | | | | | | | | |
Collapse
|
46
|
Abstract
Stem cells, one of the progenitors of cancer, exist predominately in a quiescent state. Thus, understanding the mechanisms of DNA repair and mutagenesis in such arrested cells may help unravel the complex process of tumorigenesis. Two major nucleotide excision repair (NER) pathways are known to remove bulky physical or chemical lesions from DNA. Transcription-coupled repair (TCR) acts solely on the transcribed strand of expressed genes, while global genomic repair (GGR) is responsible for the ubiquitous repair of the genome. Indirectly, it has been shown that while TCR functions in quiescent cells GGR does not. To explicitly elucidate this phenomenon, we adapted a quantitative PCR (QPCR) assay to study UV-damage repair via TCR and GGR in quiescent and proliferating cells. We present evidence that repair of untranscribed silent regions of the genome and repair of the non-transcribed strand of active genes proceeds by two discrete mechanisms in quiescent cells; rather than by GGR, which was believed to encompass both. Thus, our findings suggest the existence of an alternate NER pathway in quiescent cells. The proposed subcategories of NER are as follows: (i) TCR, responsible for maintenance of transcribed strands; (ii) GGR, responsible for ubiquitous genome repair; and (iii) non-transcribed strand repair (NTSR), predominantly responsible for the repair of the NTS in arrested cells. In quiescent cells, it is evident that TCR and NTSR function and GGR are arrested. As a consequence, mutation accumulation at temporally silent genes and incomplete or imperfect repair of transcribed genes, in quiescent stem cells, may provide a source of cancer causing mutations.
Collapse
Affiliation(s)
- Jason H Bielas
- Department of Biology, York University, 4700 Keele Street, Toronto, ON, Canada M3J 1P3.
| |
Collapse
|
47
|
Pavlov YI, Shcherbakova PV, Rogozin IB. Roles of DNA Polymerases in Replication, Repair, and Recombination in Eukaryotes. INTERNATIONAL REVIEW OF CYTOLOGY 2006; 255:41-132. [PMID: 17178465 DOI: 10.1016/s0074-7696(06)55002-8] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The functioning of the eukaryotic genome depends on efficient and accurate DNA replication and repair. The process of replication is complicated by the ongoing decomposition of DNA and damage of the genome by endogenous and exogenous factors. DNA damage can alter base coding potential resulting in mutations, or block DNA replication, which can lead to double-strand breaks (DSB) and to subsequent chromosome loss. Replication is coordinated with DNA repair systems that operate in cells to remove or tolerate DNA lesions. DNA polymerases can serve as sensors in the cell cycle checkpoint pathways that delay cell division until damaged DNA is repaired and replication is completed. Eukaryotic DNA template-dependent DNA polymerases have different properties adapted to perform an amazingly wide spectrum of DNA transactions. In this review, we discuss the structure, the mechanism, and the evolutionary relationships of DNA polymerases and their possible functions in the replication of intact and damaged chromosomes, DNA damage repair, and recombination.
Collapse
Affiliation(s)
- Youri I Pavlov
- Eppley Institute for Research in Cancer and Allied Diseases, Departments of Biochemistry and Molecular Biology, and Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska 68198-6805, USA
| | | | | |
Collapse
|
48
|
Kou T, Marusawa H, Kinoshita K, Endo Y, Okazaki IM, Ueda Y, Kodama Y, Haga H, Ikai I, Chiba T. Expression of activation-induced cytidine deaminase in human hepatocytes during hepatocarcinogenesis. Int J Cancer 2006; 120:469-76. [PMID: 17066440 DOI: 10.1002/ijc.22292] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Activation-induced cytidine deaminase (AID) plays a role as a genome mutator in activated B cells, and inappropriate expression of AID has been implicated in the immunopathological phenotype of human B-cell malignancies. Notably, we found that the transgenic mice overexpressing AID developed lung adenocarcinoma and hepatocellular carcinoma (HCC), suggesting that ectopic expression of AID can lead to tumorigenesis in epithelial tissues as well. To examine the involvement of AID in the development of human HCC, we analyzed the AID expression and its correlation with mutation frequencies of the p53 gene in liver tissues from 51 patients who underwent resection of primary HCCs. The specific expression, inducibility by cytokine stimulation and mutagenic activity of AID were investigated in cultured human hepatocytes. Only trace amounts of AID transcripts were detected in the normal liver; however, endogenous AID was significantly upregulated in both HCC and surrounding noncancerous liver tissues with underlying chronic hepatitis or liver cirrhosis (p < 0.05). Most liver tissues with underlying chronic inflammation with endogenous AID upregulation already contained multiple genetic changes in the p53 gene. In both hepatoma cell lines and cultured human primary hepatocytes, the expression of AID was substantially induced by TGF-beta stimulation. Aberrant activation of AID in hepatocytes resulted in accumulation of multiple genetic alterations in the p53 gene. Our findings suggest that the aberrant expression of AID is observed in human hepatocytes with several pathological settings, including chronic liver disease and HCC, which might enhance the genetic susceptibility to mutagenesis leading to hepatocarcinogenesis.
Collapse
MESH Headings
- Adult
- Aged
- Aged, 80 and over
- Amino Acid Sequence
- Base Sequence
- Carcinoma, Hepatocellular/genetics
- Carcinoma, Hepatocellular/metabolism
- Carcinoma, Hepatocellular/pathology
- Cell Line, Tumor
- Cells, Cultured
- Cytidine Deaminase/genetics
- Cytidine Deaminase/metabolism
- Enzyme Activation
- Female
- Gene Expression Regulation, Enzymologic/drug effects
- Gene Expression Regulation, Neoplastic/drug effects
- Hepatitis, Viral, Human/physiopathology
- Hepatocytes/enzymology
- Hepatocytes/metabolism
- Hepatocytes/virology
- Humans
- Immunoblotting
- Liver Neoplasms/genetics
- Liver Neoplasms/metabolism
- Liver Neoplasms/pathology
- Male
- Middle Aged
- Mutation/genetics
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Transforming Growth Factor beta/pharmacology
- Tumor Suppressor Protein p53/genetics
Collapse
Affiliation(s)
- Tadayuki Kou
- Department of Gastroenterology and Hepatology, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | | | | | | | | | | | | | | | | | | |
Collapse
|
49
|
Emily M, François O. Conditional coalescent trees with two mutation rates and their application to genomic instability. Genetics 2005; 172:1809-20. [PMID: 16387889 PMCID: PMC1456266 DOI: 10.1534/genetics.105.044099] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Humans have invested several genes in DNA repair and fidelity replication. To account for the disparity between the rarity of mutations in normal cells and the large number of mutations present in cancer, an hypothesis is that cancer cells must exhibit a mutator phenotype (genomic instability) during tumor progression, with the initiation of abnormal mutation rates caused by the loss of mismatch repair. In this study we introduce a stochastic model of mutation in tumor cells with the aim of estimating the amount of genomic instability due to the alteration of DNA repair genes. Our approach took into account the difficulties generated by sampling within tumoral clones and the fact that these clones must be difficult to isolate. We provide corrections to two classical statistics to obtain unbiased estimators of the raised mutation rate, and we show that large statistical errors may be associated with such estimators. The power of these new statistics to reject genomic instability is assessed and proved to increase with the intensity of mutation rates. In addition, we show that genomic instability cannot be detected unless the raised mutation rates exceed the normal rates by a factor of at least 1000.
Collapse
Affiliation(s)
- Mathieu Emily
- TIMC-TIMB Department, Faculty of Medicine, Institut de l'Ingénierie de l'Information de Santé, 38706 La Tronche, France
| | | |
Collapse
|
50
|
Tumor development: haploinsufficiency and local network assembly. Cancer Lett 2005; 240:17-28. [PMID: 16223564 DOI: 10.1016/j.canlet.2005.08.015] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2005] [Accepted: 08/15/2005] [Indexed: 01/11/2023]
Abstract
According to the current models, tumor development is a continuous process of mutation accumulation, leading to several intermediate phenotypes and final phases of autonomy, unlimited growth and metastasis. One of the most important events in that process is the initial destabilization of cellular pathways that subsequently allow mutations to accumulate. The mechanisms involved in that stage are not clear. In principle, the estimated very low mutation frequency in human or mouse cells would suggest that accumulating the required number of mutations for tumor development should be a statistically unlikely event. However, this theory is contradicted by the high incidence of cancers. Here we discuss the role of protein haploinsufficiency as a contributor to the initial phases of tumor development, and suggest possible mechanisms that might be involved in that process.
Collapse
|