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Query: UMLS:C0242379 (lung cancer)
 71,905 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

DNA base excision repair (BER) removes frequent DNA lesions of either endogenous or exogenous origin. Some indications point to BER defects in lung cancer patients. We have investigated the ability of ten lung cancer patients to repair natural AP sites, the most frequent genetic lesion, using an in vitro assay in which peripheral blood lymphocytes (PBL) extracts incise randomly depurinated plasmid DNA. The median value of repair activity in patients was lower than that of matched controls but the difference did not reach significance. Unlike other BER enzymatic steps, marked defects in incision of AP sites may not be associated with lung carcinogenesis.
Teratog Carcinog Mutagen 2002
PMID:Incision of AP sites in lung cancer patients: a pilot study. 1211 9

Bleomycin-induced chromosomal instability, generally referred to as mutagen sensitivity, is associated with an increased risk for the development of environmentally related cancer including head and neck squamous cell carcinoma and lung cancer. On average, the cultured lymphocytes of patients with these types of cancer show an increased number of chromatid breaks per cell after bleomycin exposure in the late S or G2 phase of the cell cycle as compared to lymphocytes from control persons. The aim of the present study was to investigate whether cell cycle regulation is involved in mutagen sensitivity. We determined cell cycle arrest after bleomycin-induced DNA damage in 21 lymphoblastoid cell lines that varied in mutagen sensitivity score. An ataxia telangiectasia (AT) cell line was included for comparison. Using a cut-off point of 0.70 breaks per cell, eight cell lines were classified as insensitive and 13 cell lines showed the hypersensitive phenotype. Compared to insensitive cell lines, bleomycin-treated hypersensitive cells remained at a relatively high level of DNA synthesis, as measured by thymidine incorporation, and showed a decreased accumulation of cells in G2 and M phase, as measured by flow cytometry. AT cells showed an extremely high mutagen sensitivity score, a high level of DNA synthesis, and a strong G2 block. In conclusion, mutagen sensitivity is associated with "damage-resistant growth," which is indicative of impaired cell cycle arrest. By which specific pathway(s) this checkpoint defect is explained has yet to be elucidated; however, it is probably distinct from the checkpoint defect in AT cells. Environ. Mol. Mutagen. 40:79-84, 2002.
Environ Mol Mutagen 2002
PMID:Involvement of cell cycle control in bleomycin-induced mutagen sensitivity. 1220 99

Atherosclerosis (AR) is the leading cause of morbidity and mortality in the US and cigarette smoking is a major contributing factor to the disease. Like cigarette smoking in lung cancer, genetic susceptibility may be an important factor in determining who is more likely to develop AR. However, the current emphasis has been on susceptibility based on altered cardiovascular homeostasis. In this investigation, we studied 120 AR patients and 90 matched controls to elucidate the association between polymorphisms in some metabolizing genes (GSTM1, GSTT1, CYP2E1, mEH, PON1, and MPO) and susceptibility to AR. We found that the GSTT1 null allele and the fast allele of mEH(*) (exon 4) are associated with risk for AR. Furthermore, the combined genotypes GSTM1 null/ CYP2E1(*)5B, GSTM1 null/mEH YY, and GSTT1 null/mEH YY are significantly associated with susceptibility to AR (OR = 15.42, 95% CI = 1.33-77.93, P = 0.021; OR = 3.48, 95% CI = 1.63-8.04, P = 0.0008; OR = 3.4; 95% CI = 0.99-17.38, P = 0.05; respectively). We have also conducted cytogenetic analysis to elucidate if induction of chromosome aberrations (CAs) is a biomarker of AR susceptibility. We found that among cigarette smokers (AR patients and smoker controls), individuals having the GSTM1 null allele had a significantly higher frequency of CAs compared to those with the normal allele (P < 0.05). This association was not found among nonsmokers. In addition, individuals who had inherited the CYP2E1(*)5B allele exhibited a significantly higher CA frequency (8.0 +/- 0.82) compared to those with the CYP2E1 wild-type genotype (4.31 +/- 0.35). Since the analysis of genetic susceptibility factors is still in its infancy, our study may stimulate additional investigations to understand the roles of genetic susceptibility and cigarette smoking in AR.
Environ Mol Mutagen 2002
PMID:Polymorphic metabolizing genes and susceptibility to atherosclerosis among cigarette smokers. 1235 48

The DNA repair proteins XPD and XRCC1 are involved in the nucleotide and base excision repair of DNA lesions induced by many tobacco and environmental carcinogens. Common variant alleles at the XPD (312Asn, 751Gln) and XRCC1 (399Gln) loci have been identified and associated with increased risk for lung cancer. We therefore investigated a possible effect of these variant alleles on the frequency and spectrum of p53 mutations in the tumors of 97 Swedish lung cancer patients (56 never-smokers and 41 age-, gender-, and hospital-matched ever-smokers). The p53 gene was mutated in 4 never-smokers (7%) and 11 ever-smokers (27%). Smoking-related transversion-type mutations predominated over transitions among smokers (8:3), but not among never-smokers (1:3). None of the variant alleles altered the overall frequency of p53 mutation. Transversions, however, were marginally increased among patients with at least one XPD variant allele compared with patients who were wild-type homozygotes (73% vs. 25% for the Asp312Asn polymorphism, P = 0.095; 78% vs. 33% for Lys751Gln, P = 0.085). Five of six women or six of seven smokers who carried at least one XPD 751Gln allele had p53 transversion. The XRCC1 variant allele did not show any effect on the p53 mutation. We conclude that the XPD variant alleles may be associated with an increased frequency of smoking-related p53 mutations in lung tumors, presumably due to reduced DNA repair proficiency.
Environ Mol Mutagen 2003
PMID:Influence of common XPD and XRCC1 variant alleles on p53 mutations in lung tumors. 1255 90

Environmental exposure to carcinogens and individual susceptibility play significant roles in cancer risk. Suboptimal DNA repair capability, measured by quantifying mutagen-induced chromosome breaks, might explain variable host susceptibility to environmental carcinogens. In an ongoing lung cancer case-control study, we compared individual sensitivity to bleomycin-induced chromosome breaks in 152 non-small cell lung cancer patients with 94 population controls and 85 hospital controls with no history of cancer. Mutagen sensitivity was measured by mean number of chromatid breaks per cell in cultured peripheral blood lymphocytes treated with bleomycin. Non-parametric tests and chi(2) tests were used to determine the statistical significance of the crude case-control comparisons, followed by logistic regression to adjust for important covariates. The mean number of bleomycin-induced breaks per cell was 1.01 for the cases compared with 0.86 for hospital controls (P < 0.01) and 0.89 for population controls (P < 0.01). The mean number of breaks per cell was 1.01 for those >65 years old and 0.81 for those < or = 65 years old (P < 0.01) among population controls. Defining bleomycin sensitive as >0.84 break/cell (the median level in population controls), 67% of the cases were bleomycin sensitive compared with 49% of the hospital controls [adjusted odds ratio (OR) = 2.69, 95% confidence interval (CI) = 1.44, 5.04], and 51% of the population controls (adjusted OR = 2.18, 95% CI = 1.13, 4.21). Our data indicate that the increased number of bleomycin-induced chromosome breaks was significantly associated with an increased risk of lung cancer in the first 331 subjects.
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PMID:Bleomycin-induced chromosome breaks as a risk marker for lung cancer: a case-control study with population and hospital controls. 1258 77

Fragile sites are nonrandomly located gaps and/or breaks and their expres-sion can be induced by specific culture conditions. There are many reports in the literature that indicate that these sites can act as factors that predispose to specific chromosome aberrations and other complex rearrangement in the chromosome and their association with cancers. In the present study, the expression of the fragile sites induced by aphidicolin was evaluated on prometaphase chromosomes from peripheral blood lymphocytes of 55 patients with breast cancer patients belonging to different stages of the cancer, 25 patients with epithelial ovarian cancer, and 13 with non-small-cell lung cancer, 100 of their first-degree clinically healthy female relatives, and 100 normal age-matched healthy persons without a familial history of cancer. The frequency of expression of the fragile sites in cancer patients and their first-degree relatives was found to be statistically significant (P<0.05) than those of the controls. In different stages of breast cancer patients, 6q26 is the best-defined fragile site whereas 13q13 is confined to stage II and stage III patients only. The chromosomal aberration rate/cell in breast cancer patients was found to be 0.29+/-0.13, in epithelial ovarian cancer patients 0.38+/-0.14, and in non-small-cell lung cancer 0.29+/-0.11 as compared to 0.07+/-0.03 in controls, and was found to be statistically significant. Therefore, our results indicate that these fragile sites may be the unstable sites in the genome and, hence, can be used as suitable and reliable markers for genetic predisposition to breast cancer, epithelial ovarian cancer, and in non-small-cell lung cancer.
Teratog Carcinog Mutagen 2003
PMID:Expression of aphidicolin-induced fragile sites and their relationship between genetic susceptibility in breast cancer, ovarian cancer, and non-small-cell lung cancer patients. 1261 95

We have previously investigated the role of polymorphic chemical metabolizing genes in the susceptibility to the development of lung cancer using 110 primary lung cancer patients and 119 matched smoker controls. Together with data from the present study on DNA repair genes, we did not observe significant associations between any single variant genotype for several DNA-repair and chemical-metabolizing genes (XPD [or ERCC2], XRCC1, XRCC3, GSTM1, GSTT1, MPO, and mEH [or EPHX1]) and lung cancer. In the present study, we have further evaluated a nested group of 79 patients and 69 matched controls, and observed that increased chromosome aberrations (CAs) were associated with variant DNA-repair genotypes among both the patient and the control groups, with a significant increase for individuals having the XPD Lys/Gln + Gln/Gln genotypes (P = 0.046). Patients often had significantly increased CAs compared with controls with the same DNA-repair genotype and with similar cigarette smoking habits (< or =40 pack-years or >40 pack-years). Analyses of interactions between the DNA-repair and chemical-metabolizing genes indicated that the most significant interactions were between the repair genotypes and the GSTM1/T1 null genotypes. Significant increases in CA from the interactions were often observed among patients with < or =40 pack-years, but not among those with >40 pack-years. Since some variant DNA-repair genotypes have functional deficits for DNA repair, the association between variant DNA-repair genotypes and increased CAs suggests a risk mechanism for the development of lung cancer, with the DNA-repair genotypes interacting with variant chemical metabolizing genotypes to further increase the risk. The observation that patients had significantly increased CA frequencies compared with controls, irrespective of genotype, suggests that patients have additional factors that contribute to the development of lung cancer.
Environ Mol Mutagen 2004
PMID:Polymorphisms in DNA repair genes, chromosome aberrations, and lung cancer. 1519 49

The MDM2 gene is overexpressed in several human tumors and its product may be processed into various isoforms. Recently, alternative splicing forms of MDM2 mRNA have been detected in various types of tumors. In this study, lung tissue from human non small cell lung cancers was examined for MDM2 mRNA splicing variants by nested RT-PCR. Of the 117 lung cancer tissue samples analyzed, a total of 31 (26.5%) had splice variants for the MDM2 gene, while 59 (50.4%) had undetectable levels of MDM2 transcript. Further analysis indicated that the predominant variant for 26 of the 31 samples with alternative MDM2 splicing products was MDM2-657, a splice variant lacking exons 3-11. Significant associations were found between the frequency of alternative splicing and the gender and smoking habits of the patients. Approximately 36% of male patients had alternative splicing of MDM2 compared with only 9.5% of female patients (P = 0.008); 44.2% of the smoker patients had alternative MDM2 splice forms versus 16.2% of nonsmokers (P = 0.003). Furthermore, most normal lung cell lines examined possessed only full-length MDM2 mRNA, while among several lung cancer cell lines, only H1355 and CaLu-1 cells lacked alternatively spliced MDM2 transcripts. When H1355 cells were treated in vitro with the cigarette smoke carcinogen benzo[a]pyrene (B[a]P) or the B[a]P metabolite benzo[a]pyrene diolepoxide (BPDE), three MDM2 splicing products were detected by nested RT-PCR. Finally, with the use of several specific inhibitors, we found that BPDE-induced MDM2 mRNA alternative splicing in H1355 cells may occur through the PI3K or MAPK pathway. Overall, our results suggest that carcinogens present in cigarette smoke increase the risk of alternative MDM2 splicing, which is highly associated with lung cancer.
Environ Mol Mutagen 2005 Jul
PMID:Alternative splicing of MDM2 mRNA in lung carcinomas and lung cell lines. 1571 38

A transplacental carcinogenicity study was conducted by exposing pregnant Swiss (CD-1) mice to 0, 50, 100, 200, or 300 mg of 3'-azido-3'-deoxythymidine (AZT)/kg bw/day, through a 18 to 19-day gestation [National Toxicology Program, NIH Pub. No. 04-4458, 2004]. The incidences of alveolar/bronchiolar adenomas and carcinomas, in the 200 and 300 mg/kg male treatment groups, were significantly greater than that of the controls. In the present study, we evaluated the benign and malignant lung neoplasms from this bioassay for point mutations, in the K-ras and p53 cancer genes that are often mutated in human lung tumors. K-ras and p53 mutations were detected by cycle sequencing of polymerase chain reaction-amplified DNA, isolated from formalin-fixed, paraffin-embedded neoplasms. K-ras mutations were detected in 25 of 38 (66%) of the AZT-induced lung tumors, and the predominant mutations were codon 12 G-->T transversions. p53 mutations were detected in 32 of 38 (84%) of the AZT-induced lung tumors, with the predominant mutations being exon 8, codon 285 A-->T transversions, and exon 6, codon 198 T-->A transversions. No K-ras or p53 mutations were detected in five tumors, examined from control mice. The patterns of mutations identified in the lung tumors suggest that incorporation of AZT or its metabolites into DNA, oxidative stress, and genomic instability may be the contributing factors to the mutation profile and development of lung cancer in these mice.
Environ Mol Mutagen
PMID:Genetic alterations in K-ras and p53 cancer genes in lung neoplasms from Swiss (CD-1) male mice exposed transplacentally to AZT. 1639 94

Epidemiological studies indicate that there is a gender difference in the susceptibility to tobacco and environmental carcinogens, and this gender difference is suspected to result in a higher risk for lung cancer among women. However, the molecular mechanisms underlying this sexual dimorphism remain unclear. In the present study, we have evaluated the roles of CYP1A1 and dihydrodiol dehydrogenase (DDH) in the formation of benzo[a]pyrene (BaP) DNA adducts in various lung cancer cell lines. Among six lung cancer cell lines tested, higher adduct levels were observed in CL-3 and CL1-1 cells, which had relatively high expression of both CYP1A1 and DDH isoform 1 (DHH1). To determine whether a reduction in DDH expression changed the adduct levels, an siRNA was used to knock down DDH1 expression in CL-3 cells. The BaP adduct levels in siDDH-CL-3 cells increased 1.4-2.2-fold relative to that of the parental CL-3 cells. We also examined BaP-like DNA adducts, and CYP1A1 and DDH1 expression by immunohistochemistry in 120 lung tumors. Detection of DNA adducts correlated with CYP1A1-positive tumors (P = 0.023), but not with DDH1-positive tumors. In addition, 28 of 33 tumors (85%) that were CYP1A1-positive and DDH1-negative contained detectable levels of DNA adducts, a proportion that was higher than for tumors from the other three categories of CYP1A1 and DDH1 expression (P = 0.012). Finally, a greater proportion of adduct-positive tumors from females were CYP1A1-positive/DDH1-negative (45.3%) than were tumors from males (27.3%). These results suggest that the reduction of DDH expression in lung tumors may contribute to an increase in DNA adduct levels, which may be partly responsible for the higher susceptibility of female lung cancer patients to DNA damage.
Environ Mol Mutagen 2007 Jan
PMID:A possible role for dihydrodiol dehydrogenase in the formation of benzo[a]pyrene-DNA adducts in lung cancer cells and tumor tissues. 1716 6


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