摘要 :
Rationale. Tobacco smoking is responsible for 85% of all lung cancers. To further our understanding of the molecular pathogen-esis of lung cancer, we determined whether smoking history leads to the emergence of specific genomic al...
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Rationale. Tobacco smoking is responsible for 85% of all lung cancers. To further our understanding of the molecular pathogen-esis of lung cancer, we determined whether smoking history leads to the emergence of specific genomic alterations found in non-small cell lung cancer (NSCLC).
Objectives: To identify gene copy number alterations in NSCLCs associated with smoking history or DNA repair capacity. Methods: Seventy-five NSCLCs were selected for this study from patients with current, none, or past smoking history, including pack year information. Tissue sections were microdissected, and DNA was extracted, purified, and labeled by random priming before hybridization onto bacterial artificial chromosome (BAC) arrays. Normalized ratios were correlated with smoking history and DNA repair capacity was measured by an in vitro lymphocyte assay in the same patients.
Measurements and Main Results: We identified smoking-related genomic signatures in NSCLCs that could be predicted with an overall 74% accuracy. Lung tumors arising from current-smokers had the greatest number of copy number alterations. The genomic regions most significantly associated with smoking were located within 60 regions and were functionally associated with genes controlling the M phase of the cell cycle, the segregation of chromosomes, and the methylation of DNA. Verification of the data is provided from data in the public domain and by quantitative real-time polymerase chain reaction. The associations between genomic abnormalities and DNA repair capacity did not reach statistical significance. Conclusions: These findings indicate that smoking history leaves a specific genomic signature in the DNA of lung tumors and suggest that these alterations may reflect new molecular pathways to cancer development.
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DNA double-strand breaks (DSBs) may lead to genomic instability and cancer if unrepaired. Nijmegen breakage syndrome 1 (NBS1) protein is one of the key proteins that participates in recognition and repair of DSBs in humans. We hyp...
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DNA double-strand breaks (DSBs) may lead to genomic instability and cancer if unrepaired. Nijmegen breakage syndrome 1 (NBS1) protein is one of the key proteins that participates in recognition and repair of DSBs in humans. We hypothesized that polymorphisms of NBS1 are associated with breast cancer risk. We selected three NBS1 haplotype-tagging polymorphisms (i.e. 924T>C, 8360G>C and 30537G>C) to represent all common (≥5%) haplotypes reported in the National Institute of Environmental Health Sciences database and to reconstruct haplotypes. In a hospital-based case–control study of 421 non-Hispanic white patients with sporadic breast cancer (≤55 years) and 423 cancer-free controls who were frequency-matched with the cases by age (±5 years and ≤55), we tested our hypothesis and found that compared with 924TT homozygotes the variant homozygote 924CC carriers had a 4.55-fold increased risk of breast cancer [95% confidence interval (CI) = 1.51–13.7] and that compared with the 8360GG genotype the variant genotypes were also associated with a significantly increased risk [adjusted odds ratio (OR) = 1.33, 95% CI = 1.00–1.78 for 8360CG; adjusted OR = 1.83, 95% CI = 1.14–2.94 for 8360CC]. However, these effects were not observed for the 30537G>C polymorphism. Furthermore, the derived haplotypes were associated with risk in a dose–response manner as the number of variant (risk) alleles (i.e. 8360C, 924C or 30537C) increased (adjusted OR = 1.07, 95% CI = 0.78–1.46 for 1–2 variant alleles; adjusted OR = 2.47, 95% CI = 1.48–4.14 for 3–6 variant alleles; Ptrend = 0.006). These findings suggest that NBS1 polymorphisms and haplotypes may contribute to the etiology of sporadic breast cancer in young non-Hispanic white women. Large studies are warranted to confirm these findings.
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p53-binding protein 1 (P53BP1), a central transducer of DNA-damage signals to p53, is required for both intra-S-phase and G2-M checkpoints, suggesting that these two proteins may work together in the p53-mediated transcriptional a...
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p53-binding protein 1 (P53BP1), a central transducer of DNA-damage signals to p53, is required for both intra-S-phase and G2-M checkpoints, suggesting that these two proteins may work together in the p53-mediated transcriptional activation and DNA damage-repair signaling pathways. Because the p53-binding region of 53BP1 maps to the C-terminal BRCT domains, which are homologous to those found in the breast cancer protein BRCA1, we hypothesized that genetic variation in P53BP1 and p53 may contribute to breast cancer predisposition. To test this hypothesis, we simultaneously genotyped single nucleotide polymorphisms of T-885G, Glu353Asp, and Gln1136Lys in P53BP1 and Arg72Pro in p53 in a case–control study of 404 breast cancer cases and 472 cancer-free controls. We found that the P53BP1 variant genotypes (alleles) of T-885G and Gln1136Lys were associated with a significantly increased risk of breast cancer among p53 Pro/Pro carriers (OR = 2.36, 95% CI 1.16–4.83 for −885TG/GG; OR = 2.24, 95% CI 1.15–4.37 for 1136Gln/Lys + Lys/Lys and OR = 2.82, 95% CI 1.15–6.94 for >4 variant alleles of these 3 loci). In addition, the variant genotypes of above 3 loci of P53BP1 were significantly associated with elevated risk of progesterone receptor (PR) negative breast cancer, and the T-885G and Gln1136Lys with estrogen receptor (ER) negative breast cancer. Furthermore, we found a significant gene-gene interaction between P53BP1 Gln1136Lys and p53 Arg72Pro variants in relation to breast cancer, and the OR of interaction for the presence of both P53BP1 1136Gln/Lys + Lys/Lys and p53 72Arg/Pro + Pro/Pro genotypes was 1.93 (95% CI 1.06–3.52) (P = 0.031 for interaction). These findings indicate that the SNPs in P53BP1 and p53 jointly contribute to breast cancer risk, particularly ER (−) or PR (−) breast cancer, and the p53 Arg72Pro polymorphism may serve as a risk modifier. Further functional studies are needed to confirm our findings.
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DNA damage binding protein 2 (DDB2) is one of the major DNA repair proteins involved in the nucleotide excision repair (NER) pathway. Mutations in the DDB2 gene can cause a repair-deficiency syndrome xeroderma pigmentosum group E....
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DNA damage binding protein 2 (DDB2) is one of the major DNA repair proteins involved in the nucleotide excision repair (NER) pathway. Mutations in the DDB2 gene can cause a repair-deficiency syndrome xeroderma pigmentosum group E. Because tobacco carcinogens can cause DNA damage that is repaired by NER and suboptimal NER capacity is reported to be associated with lung cancer risk, we hypothesized that common variants in the DDB2 gene are associated with lung cancer risk. To test this hypothesis, we conducted a case–control study of 1010 patients with incident lung cancer and 1011 cancer-free controls and genotyped two DDB2 single nucleotide polymorphisms (SNPs) (rs830083 and rs3781620) that are in linkage disequilibrium with other untyped SNPs. We found that compared with the rs830083CC, subjects carrying the heterozygous rs830083CG genotype had a significantly 1.31-fold increased risk of lung cancer [95% confidence interval (CI) 1.08–1.60] and those carrying the homozygous rs830083GG genotype had a non-significantly 1.22-fold elevated risk (95% CI 0.89–1.67). In addition, effects of the combined rs830083CG/GG variant genotypes were more evident in young subjects, heavy smokers and subjects with a positive family history of cancer. These findings indicate, for the first time, that the DDB2 rs830083 polymorphism may contribute to the etiology of lung cancer. Further functional studies on this SNP and/or related variants are warranted to elucidate the underlying molecular mechanisms of the association.
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摘要 :
Mutagen sensitivity is regarded as a genetic susceptibility phenotype for various cancers; it is cytogenetically based and probably involves a number of genes from different DNA repair pathways. This assay has been used in a numbe...
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Mutagen sensitivity is regarded as a genetic susceptibility phenotype for various cancers; it is cytogenetically based and probably involves a number of genes from different DNA repair pathways. This assay has been used in a number of laboratories in the field of epidemiology, where it has been investigated and appears to be a useful susceptibility biomarker for epidemiological studies assessing cancer risks at the population level. One concern about phenotypic assays, such as the mutagen sensitivity assay, has been that there could be wide variation in results depending on the timing of the assay (within individual variation), the individual performing the assay (within observer variation) and the laboratory where the assay has been performed (inter-laboratory variation). We conducted an inter-laboratory comparison study between the Memorial Sloan-Kettering Cancer Center and M. D. Anderson, in which we assessed all these concerns. We did not find any significant variation in any of the assays. The correlation was high for all tests. The good concordance rate between laboratories supports the continued use of the mutagen sensitivity assay by different laboratories, and demonstrates its potential to identify at-risk subgroups among normal individuals and cancer patients alike.
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