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Abstract
The chemistry of DNA and its repair selectivity control the influence of genomic oxidative stress on the development of serious disorders such as cancer and heart diseases. DNA is oxidized by endogenous reactive oxygen species (ROS) in vivo or in vitro as a result of high energy radiation, non-radiative metabolic processes, and other consequences of oxidative stress. Some oxidations of DNA and tumor suppressor gene p53 are thought to be mutagenic when not repaired. For example, site-specific oxidations of p53 tumor suppressor gene may lead to cancer-related mutations at the oxidation site codon. This review summarizes the research on the primary products of the most easily oxidized nucleobase guanine (G) when different oxidation methods are used. Guanine is by far the most oxidized DNA base. The primary initial oxidation product of guanine for most, but not all, pathways is 8-oxoguanine (8-oxoG). With an oxidation potential much lower than G, 8-oxoG is readily susceptible to further oxidation, and the products often depend on the oxidants. Specific products may control the types of subsequent mutations, but mediated by gene repair success. Site-specific oxidations of p53 tumor suppressor gene have been reported at known mutation hot spots, and the codon sites also depend on the type of oxidants. Modern methodologies using LC-MS/MS for codon specific detection and identification of oxidation sites are summarized. Future work aimed at understanding DNA oxidation in nucleosomes and interactions between DNA damage and repair is needed to provide a better picture of how cancer-related mutations arise.
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Affiliation(s)
- Di Jiang
- Department of ChemistryUniversity of ConnecticutStorrsCT 06269United States
| | - James F. Rusling
- Department of ChemistryUniversity of ConnecticutStorrsCT 06269United States
- Department of SurgeryNeag Cancer Center, UConn HealthFarmingtonCT 06032United States
- Institute of Material ScienceUniversity of ConnecticutStorrsCT 06269United States
- School of ChemistryNational University of Ireland at GalwayIreland
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Jiang D, Malla S, Fu YJ, Choudhary D, Rusling JF. Direct LC-MS/MS Detection of Guanine Oxidations in Exon 7 of the p53 Tumor Suppressor Gene. Anal Chem 2017; 89:12872-12879. [PMID: 29116749 PMCID: PMC5777150 DOI: 10.1021/acs.analchem.7b03487] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Oxidation of DNA by reactive oxygen species (ROS) yields 8-oxo-7,8-dihydroguanosine (8-oxodG) as primary oxidation product, which can lead to downstream G to T transversion mutations. DNA mutations are nonrandom, and mutations at specific codons are associated with specific cancers, as widely documented for the p53 tumor suppressor gene. Here, we present the first direct LC-MS/MS study (without isotopic labeling or hydrolysis) of primary oxidation sites of p53 exon 7. We oxidized a 32 base pair (bp) double-stranded (ds) oligonucleotide representing exon 7 of the p53 gene. Oxidized oligonucleotides were cut by a restriction endonuclease to provide small strands and enable positions and amounts of 8-oxodG to be determined directly by LC-MS/MS. Oxidation sites on the oligonucleotide generated by two oxidants, catechol/Cu2+/NADPH and Fenton's reagent, were located and compared. Guanines in codons 243, 244, 245, and 248 were most frequently oxidized by catechol/Cu2+/NADPH with relative oxidation of 5.6, 7.2, 2.6, and 10.7%, respectively. Fenton's reagent oxidations were more specific for guanines in codons 243 (20.3%) and 248 (10.4%). Modeling of docking of oxidizing species on the ds-oligonucleotide were consistent with the experimental codon oxidation sites. Significantly, codons 244 and 248 are mutational "hotspots" in nonsmall cell and small cell lung cancers, supporting a possible role of oxidation in p53 mutations leading to lung cancer.
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Affiliation(s)
- Di Jiang
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269, United States
| | - Spundana Malla
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269, United States
| | - You-jun Fu
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269, United States
| | - Dharamainder Choudhary
- Department of Surgery and Neag Cancer Center, UConn Health, Farmington, Connecticut 06032, United States
| | - James F. Rusling
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269, United States
- Department of Surgery and Neag Cancer Center, UConn Health, Farmington, Connecticut 06032, United States
- Institute of Material Science, University of Connecticut, Storrs, Connecticut 06269, United States
- School of Chemistry, National University of Ireland at Galway, Galway H91 TK33, Ireland
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Loeb KR, Asgari MM, Hawes SE, Feng Q, Stern JE, Jiang M, Argenyi ZB, de Villiers EM, Kiviat NB. Analysis of Tp53 codon 72 polymorphisms, Tp53 mutations, and HPV infection in cutaneous squamous cell carcinomas. PLoS One 2012; 7:e34422. [PMID: 22545084 PMCID: PMC3335843 DOI: 10.1371/journal.pone.0034422] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Accepted: 02/28/2012] [Indexed: 12/26/2022] Open
Abstract
Background Non-melanoma skin cancers are one of the most common human malignancies accounting for 2–3% of tumors in the US and represent a significant health burden. Epidemiology studies have implicated Tp53 mutations triggered by UV exposure, and human papilloma virus (HPV) infection to be significant causes of non-melanoma skin cancer. However, the relationship between Tp53 and cutaneous HPV infection is not well understood in skin cancers. In this study we assessed the association of HPV infection and Tp53 polymorphisms and mutations in lesional specimens with squamous cell carcinomas. Methods We studied 55 cases of histologically confirmed cutaneous squamous cell carcinoma and 41 controls for the presence of HPV infection and Tp53 genotype (mutations and polymorphism). Results We found an increased number of Tp53 mutations in the squamous cell carcinoma samples compared with perilesional or control samples. There was increased frequency of homozygous Tp53-72R polymorphism in cases with squamous cell carcinomas, while the Tp53-72P allele (Tp53-72R/P and Tp53-72P/P) was more frequent in normal control samples. Carcinoma samples positive for HPV showed a decreased frequency of Tp53 mutations compared to those without HPV infection. In addition, carcinoma samples with a Tp53-72P allele showed an increased incidence of Tp53 mutations in comparison carcinomas samples homozygous for Tp53-72R. Conclusions These studies suggest there are two separate pathways (HPV infection and Tp53 mutation) leading to cutaneous squamous cell carcinomas stratified by the Tp53 codon-72 polymorphism. The presence of a Tp53-72P allele is protective against cutaneous squamous cell carcinoma, and carcinoma specimens with Tp53-72P are more likely to have Tp53 mutations. In contrast Tp53-72R is a significant risk factor for cutaneous squamous cell carcinoma and is frequently associated with HPV infection instead of Tp53 mutations. Heterozygosity for Tp53-72R/P is protective against squamous cell carcinomas, possibly reflecting a requirement for both HPV infection and Tp53 mutations.
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Affiliation(s)
- Keith R. Loeb
- Divisions of Clinical Research, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
- Department of Pathology, University of Washington School of Medicine, Seattle, Washington, United States of America
| | - Maryam M. Asgari
- Department of Epidemiology, University of Washington School of Medicine, Seattle, Washington, United States of America
| | - Stephen E. Hawes
- Department of Epidemiology, University of Washington School of Medicine, Seattle, Washington, United States of America
| | - Qinghua Feng
- Department of Pathology, University of Washington School of Medicine, Seattle, Washington, United States of America
| | - Joshua E. Stern
- Department of Pathology, University of Washington School of Medicine, Seattle, Washington, United States of America
| | - Mingjun Jiang
- Institute of Dermatology, National Academy of Medical Sciences, Nanjing, People’s Republic of China
| | - Zsolt B. Argenyi
- Department of Pathology, University of Washington School of Medicine, Seattle, Washington, United States of America
- Division of Dermatology, University of Washington School of Medicine, Seattle, Washington, United States of America
| | - Ethel-Michele de Villiers
- Division for the Characterization of Tumorviruses, Deutsches Krebsforschungszentrum, Heidelberg, Germany
| | - Nancy B. Kiviat
- Department of Pathology, University of Washington School of Medicine, Seattle, Washington, United States of America
- Department of Medicine, University of Washington School of Medicine, Seattle, Washington, United States of America
- * E-mail:
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Worswick SD, Cockburn M, Peng D. Measurement of Ultraviolet Exposure in Epidemiological Studies of Skin and Skin Cancers. Photochem Photobiol 2008; 84:1462-72. [DOI: 10.1111/j.1751-1097.2008.00367.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Hanausek M, Walaszek Z, Slaga T. Redox Modulation in Tumor Initiation, Promotion, and Progression. OXIDATIVE STRESS AND DISEASE 2003. [DOI: 10.1201/9780203912874.ch9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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Abstract
Recent years have seen a steady rise in the incidence of cutaneous malignant melanoma worldwide. Although it is now appreciated that the key to understanding the process by which melanocytes are transformed into malignant melanoma lies in the interplay between genetic factors and the ultraviolet (UV) spectrum of sunlight, the nature of this relation has remained obscure. Recently, prospects for elucidating the molecular mechanisms underlying such gene-environment interactions have brightened considerably through the development of UV-responsive experimental animal models of melanoma. Genetically engineered mice and human skin xenografts constitute novel platforms upon which to build studies designed to elucidate the pathogenesis of UV-induced melanomagenesis. The future refinement of these in vivo models should provide a wealth of information on the cellular and genetic targets of UV, the pathways responsible for the repair of UV-induced DNA damage, and the molecular interactions between melanocytes and other skin cells in response to UV. It is anticipated that exploitation of these model systems will contribute significantly toward the development of effective approaches to the prevention and treatment of melanoma.
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Affiliation(s)
- Chamelli Jhappan
- Molecular Genetics Section, Laboratory of Molecular Biology, National Cancer Institute, Bethesda, MD 20892-4264, USA
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Short Interspersed DNA Element-mediated detection of UVB-induced DNA damage and repair in the mouse genome, in vitro, and in vivo in skin. ACTA ACUST UNITED AC 1999. [DOI: 10.1016/s0921-8777(99)00007-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Abstract
Genotypic selection enriches a particular DNA sequence relative to another closely-related DNA sequence based only on a change of one or a few bases. This review is a survey of the genotypic selection methods that have the sensitivity to detect rare point mutations. These methods are primarily being used to study mutations caused by environmental mutagens; however, the ability to detect and measure very minor DNA sequence populations is likely to further research efforts in many fields. The approaches for allele-selection have intrinsic strengths and weaknesses, and vary greatly in sensitivity. The most sensitive method is Restriction Fragment Length Polymorphism/Polymerase Chain Reaction (RFLP/PCR) by which mutant fractions as low as 1 mutant allele in 10(8) wild-type alleles can be detected. The RFLP/PCR approach is presented as a prototype genotypic selection method. Genotypic selection methods are categorized in terms of those that (1) selectively destroy the abundant or wild-type allele, (2) selectively amplify the rare or mutant allele, or (3) spatially separate the alleles. Issues relevant to the further development of genotypic selection methods include initial DNA pool size, strategies to eliminate the bulk of extraneous DNA, the use of an internal copy number standard in quantitative PCR, the fidelity of thermostable DNA polymerases, and the effective use of PCR in linking two or more genotypic selection techniques. We conclude that proficient genotypic selection requires more than one allele-enrichment technique with at least one of these preceding a high-fidelity PCR amplification step.
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Affiliation(s)
- B L Parsons
- Division of Genetic Toxicology, HFT-120, National Center for Toxicological Research, Jefferson, AR 72079, USA.
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Moshinsky DJ, Wogan GN. UV-induced mutagenesis of human p53 in a vector replicated in Saccharomyces cerevisiae. Proc Natl Acad Sci U S A 1997; 94:2266-71. [PMID: 9122183 PMCID: PMC20076 DOI: 10.1073/pnas.94.6.2266] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Mutation of the p53 tumor suppressor gene is the most common genetic alteration identified to date in human cancers. Similarities of p53 mutations found in human cancers with those induced in experimental systems have been interpreted as evidence supporting a causative role for environmental carcinogens in certain tumor types. We have developed and validated a method for generation of mutation spectra and measurement of mutation frequency directly on human p53 cDNA in a vector following treatment with mutagens and replication in yeast. Mutants that had lost the DNA binding/transcription activation function of p53 were detected by yeast colony color, isolated, and sequenced. UV light was used to characterize and validate the system, and a dose-dependent increase in mutation frequency was seen following exposure of the plasmid to increasing doses of UV, resulting in an 18-fold increase over the spontaneous frequency (3.2 x 10(-4)) at the highest level tested (300 J/m2). Sequence analysis of p53 in the mutants revealed that the types of mutations induced were similar to those obtained in previous studies of UV mutagenesis in other model systems, and the types and positions of mutations were also similar to those found in human skin tumors. This experimental system will be useful in further evaluation of the importance of environmental agents as risk factors for cancer.
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Affiliation(s)
- D J Moshinsky
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge 02139, USA
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Amstad PA, Cerutti PA. Ultraviolet-B-light-induced mutagenesis of C-H-ras codons 11 and 12 in human skin fibroblasts. Int J Cancer 1995; 63:136-9. [PMID: 7558442 DOI: 10.1002/ijc.2910630124] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Mutations in the ras oncogene are detected with a high frequency in non-melanoma skin cancer. Approximately half of the squamous-cell carcinomas (SCC) and one third of the basal-cell carcinomas (BCC) carry mutations at the second position of Ha-ras codon 12 (GGC to GTC), whereas mutations in Ki-ras codon 12 occur less frequently. Since the mutations in the Ha-ras and Ki-ras oncogenes are located opposite potential pyrimidine dimer sites (C-C), it is likely that the mutations are induced by ultraviolet radiation present in sunlight. We studied the capacity of ultraviolet B (UVB) light to induce base-pair changes in Ha-ras codons 11 and 12 in human skin fibroblasts. UVB induced mostly C to T and G to A transitions and C to A and G to T transversions. The base-pair change with the highest relative abundance was C to T in the middle position of codon 11 followed by (in diminishing relative abundance) C to A in the middle position of codon 11, G to A and G to T in the middle position of codon 12. The C to T and G to A transitions are compatible with pyrimidine photodimers as pre-mutagenic lesions, whereas the C to A and G to T transversions could be generated due to the formation of 8-hydroxyguanine, which is the major oxidation product of guanine. The relative abundance of mutations induced by UVB in Ha-ras codons 11 and 12 does not correlate with mutations observed in the DNA from non-melanoma skin cancer, where the G to T transversion in the middle position of codon 12 is selected.
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Affiliation(s)
- P A Amstad
- Department of Pathology, University of Maryland, Baltimore 21201-1192, USA
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11
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Affiliation(s)
- C Götz
- Department of Medical Biochemistry, University of the Saarland, Homburg, Germany
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12
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