APE1 Asp148Glu Research Articles

Genetic polymorphisms of DNA repair genes and chromosomal damage in workers exposed to 1,3-butadiene

The base excision repair (BER) pathway is important in repairing DNA damage incurred from occupational exposure to 1,3-butadiene (BD). This study examines the relationship between inherited polymorphisms of the BER pathway (x-ray repair cross-complementing group 1 (XRCC1) Arg194Trp, Arg280His, Arg399Gln, T-77C, ADPRT Val762Ala, MGMT Leu84Phe and APE1 Asp148Glu) and chromosomal damage in BD-exposed workers, using the cytokinesis-blocked (CB) micronucleus (MN) assay in peripheral lymphocytes of 166 workers occupationally exposed to BD and 41 non-exposed healthy individuals. The MN frequency of exposed workers (3.39 +/- 2.42) per thousand was higher than that of the non-exposed groups (1.48 +/- 1.26) per thousand (P < 0.01). Workers receiving greater than median annual BD exposures had higher MN values than lower exposed workers: frequency ratio (FR) of 1.30, 95% confidence interval (CI) 1.14-1.53; P < 0.05. Workers who carried the following genotypes were associated with greater frequency of MN (P < 0.05 for each comparison, unless specified): XRCC1 -77 C/T genotype (FR = 1.28, 95% CI: 1.04-1.57; reference C/C), ADPRT 762 Ala/Ala (FR = 1.54, 95% CI: 1.17-2.03; P < 0.01), XRCC1 194 Arg/Trp (FR = 1.13, 95% CI: 0.87-1.27; reference, Arg/Arg), XRCC1 280 Arg/His (FR = 1.67, 95% CI: 1.10-2.42; reference, Arg/Arg), XRCC1 399 Arg/Gln and Gln/Gln genotypes (FR = 1.26, 95% CI: 1.03-1.53 and FR = 1.24, 95% CI 1.03-1.49; reference Arg/Arg, respectively). As XRCC1 polymorphisms were linked, workers carrying the XRCC1 (-77)-(194)-(280)-(399) diplotype, TCGA/TCGA, had a higher MN frequency compared with individuals carrying the wild-type CCGG/CCGG (FR = 1.57, 95% CI: 1.02-2.41; P < 0.05). In conclusion, CB-MN is a sensitive index of early damage among BD-exposed workers. In workers exposed to BD, multiple BER polymorphisms and a XRCC1 haplotype were associated with differential levels of chromosome damage.

DNA repair genes in endometriosis

Several polymorphisms in the DNA repair gene are thought to have significant effects on cancer risk. We investigated the association of polymorphisms in the DNA repair genes XRCC1 Arg399Gln, XRCC3 Thr241Met, XPD Lys751Gln, XPG Asp1104His, APE1 Asp148Glu, and HOGG1 Ser326Cys with endometriosis risk. Genotypes were determined by PCR-RFLP assays in 52 patients with endometriosis and 101 age-matched healthy controls. Although there were no significant (P > 0.05) differences in the frequencies of genotypes or alleles of APE1, XRCC1, XPD, XPG, and HOGG1 genes between patients and controls, the frequency of the XRCC3 Thr/Thr genotype was significantly greater in endometriosis patients compared with controls (P = 0.005). XRCC3 Thr/Met genotypes (P = 0.022), and the Met allele (P = 0.005) seem to have a protective role against endometriosis. The distributions of genotypes and alleles of the genes APE1, XRCC1, XRCC3, XPD, XPG, and HOGG1 were not significantly associated with the different stages of endometriosis (P > 0.05). We conclude that the XRCC3 Thr/Thr genotype is associated with endometriosis in Turkish women.

6100 S-1 enhances radiosensitivity in a mouse xenograft model of human colon cancer

Polymorphisms in DNA repair genes may be associated with differences in DNA repair capacity, thereby influencing the individual susceptibility to smoking-related cancer. We investigated the association of 10 base-excision and nucleotide-excision repair gene polymorphisms (XRCC1 −77 T/C, Arg194Trp, Arg280His and Arg399Gln; APE1 Asp148Glu; OGG1 Ser326Cys; XPA −4 G/A; XPC PAT; XPD Asp312Asn and Lys751Gln) with lung cancer risk in Caucasians. Genotypes were determined by PCR–RFLP and PCR-single base extension assays in 110 lung cancer patients and 110 age- and sex-matched controls, and the results were analyzed using logistic regression adjusted for relevant covariates. A significant association between the APE1 Asp148Glu polymorphism and lung cancer risk was found, with adjusted odds ratios (OR) of 3.38 (p = 0.001) for the Asp/Glu genotype and 2.39 (p = 0.038) for the Glu/Glu genotype. Gene–smoking interaction analyses revealed a statistically significant interaction between cumulative cigarette smoking and the XRCC1 Arg399Gln and XPD Lys751Gln polymorphisms: these polymorphisms were significantly associated with lung cancer in nonsmokers and light smokers (<25 PY; OR = 4.92, p = 0.021 for XRCC1 399 Gln/Gln; OR = 3.62, p = 0.049 for XPD 751 Gln/Gln), but not in heavy smokers (≥25 PY; OR = 0.68, p = 0.566 for XRCC1 399 Gln/Gln; OR = 0.46, p = 0.295 for XPD 751 Gln/Gln). Both the XRCC1 Arg194Trp and Arg280His as well as the OGG1 Ser326Cys heterozygous genotypes were associated with a significantly reduced risk for lung cancer (OR = 0.32, p = 0.024; OR = 0.25, p = 0.028; OR = 0.51, p = 0.033, respectively). No associations with lung cancer risk were found for the XRCC1 −77 T/C, the XPA −4 G/A and the XPC PAT polymorphisms. In conclusion, the APE1 Asp148Glu polymorphism is highly predictive for lung cancer, and cumulative cigarette smoking modifies the associations between the XRCC1 Arg399Gln and the XPD Lys751Gln polymorphisms and lung cancer risk.

Genetic polymorphisms in XRCC1, OGG1, APE1 and XRCC3 DNA repair genes, ionizing radiation exposure and chromosomal DNA damage in interventional cardiologists

Interventional cardiologists working in high-volume cardiac catheterization laboratory are exposed to significant occupational radiation risks. Common single-nucleotide polymorphisms (SNPs) in DNA repair genes are thought to modify the effects of low-dose radiation exposure on DNA damage, the main initiating event in the development of cancer and hereditary disease. The aim of this study was to determine the relationship between XRCC1 ( Arg194Trp and Arg399Gln), OGG1 ( Ser326Cys), APE1 ( Asp148Glu) and XRCC3 ( Thr241Met) SNPs and chromosomal DNA damage. We enrolled 77 subjects: 40 interventional cardiologists (27 male, 41.3 ± 9.4 years and 13 female, 37.8 ± 8.4 years) and 37 clinical cardiologists (26 male, 39.4 ± 9.5 years and 11 female, 35.0 ± 9.8 years) without radiation exposure as the control group. Micronucleus (MN) assay was performed as biomarker of chromosomal DNA damage and an early predictor of cancer. MN frequency was significantly higher in interventional cardiologists than in clinical physicians (19.7 ± 7.8‰ vs. 13.5 ± 6.3‰, p = 0.0003). Within the exposed group, individuals carrying a XRCC3 Met241 allele had higher frequency than homozygous XRCC3 Thr241 (21.2 ± 7.8‰ vs. 16.6 ± 7.1‰, p = 0.03). Individuals with two or more risk alleles showed a higher MN frequency when compared to subjects with one or no risk allele (18.4 ± 6.6‰ vs. 14.4 ± 6.1‰, p = 0.02). An interactive effect was found between smoking, exposure >10 years and the presence of the two or more risk alleles on the MN frequency ( F = 6.3, p = 0.02). XRCC3 241Met alleles, particularly in combination with multiple risk alleles of DNA repair genes, contribute to chromosomal DNA damage levels in interventional cardiologists.

Single nucleotide polymorphisms in base-excision repair genes hOGG1, APE1 and XRCC1 do not alter risk of Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder with a poorly understood etiology. There is considerable evidence that oxidative stress occurs in AD and increased DNA damage has been found in brain tissues and leukocytes of AD patients. Base excision repair (BER) is the major pathway responsible for removing oxidative DNA damage. Polymorphisms in DNA-repair genes have been associated with the increased risk of several age-related disorders including various types of cancer and could also be related to the etiology of AD. We conducted a case-control study including 91 patients with AD and age- and sex-matched 93 control subjects to examine the role of single nucleotide polymorphisms of BER genes, hOGG1 (Ser326Cys), APE1 (Asp148Glu) and XRCC1 (Arg280His and Arg399Gln) as a risk factor for AD. The frequencies of the hOGG1-Ser326Cys, APE1-Asp148Glu and XRCC1-Arg280His and XRCC1-Arg399Gln variant alleles in our control group were 0.23, 0.31, 0.10 and 0.33, respectively. No significant association was observed between the variant alleles of hOGG1-Ser326Cys (OR=1.32, 95% CI=0.83-2.11), APE1-Asp148Glu (OR=1.08, 95% CI=0.70-1.68), XRCC1-Arg280His (OR=0.53, 95% CI=0.24-1.14) and XRCC1-Arg399Gln (OR=1.05, 95% CI=0.68-1.63) and AD. Our results suggest that the polymorphic variants of these BER genes are not independent risk factors for AD.

Polymorphisms of the NER pathway genes, ERCC1 and XPD are associated with esophageal adenocarcinoma risk

Functional variation in DNA repair capacity through single nucleotide polymorphisms (SNPs) of key repair genes is associated with a higher risk of developing various types of cancer. Studies have focused on the nucleotide excision repair (NER) and base excision repair (BER) pathways. We investigated whether variant alleles in seven SNPs within these pathways increased the risk of esophageal adenocarcinoma. DNA was extracted from prospectively collected blood specimens. The samples were genotyped for SNPs in NER genes (XPD Lys751Gln, XPD Asp312Asn, ERCC1 8092C/A, and ERCC1 118C/T), and BER genes (XRCC1 Arg399Gln, APE1 Asp148Glu, and hOGG1 Ser326Cys). The presence of variant alleles was correlated with risk of esophageal adenocarcinoma both individually and jointly. Variant alleles in NER SNPs XPD Lys751Gln (AOR = 1.50, 95% CI 1.1-2.0), ERCC1 8092 C/A (AOR = 1.44, 95% CI 1.1-1.9), and ERCC1 118C/T (AOR = 1.42, 95% CI 1.0-1.9) were individually associated with esophageal adenocarcinoma risk. An increasing number of variant alleles in NER SNPs showed a significant trend with esophageal adenocarcinoma risk (p = 0.007). The presence of variant alleles in NER genes increases risk of esophageal adenocarcinoma. There is evidence of an additive role for SNPs along a common DNA repair pathway. Future larger studies of esophageal adenocarcinoma etiology should evaluate entire biological pathways.

Prognostic significance of nuclear excision (NER) and base excision (BER) DNA repair gene polymorphisms in esophageal cancer

2511 Background: DNA repair pathways are involved in cisplatin-induced damage (NER pathway) &amp; radiation damage (BER pathway). Some single nucleotide polymorphisms (SNPs) of DNA repair genes are associated with DNA repair capacity, cancer risk &amp; outcomes. We investigated the prognostic significance of 7 NER/BER SNPs on disease free (DFS) &amp; overall survival (OS) in esophageal cancer. Methods: 150 patients with esophageal cancer treated with cisplatin-based chemoradiation &amp; surgery were genotyped for BER (XRCC1 Arg399Gln; APE1 Asp148Glu; hOGG1 Ser326Cys) &amp; NER (ERCC1 8092C/A; ERCC1 codon 118 C/T; XPD Asp312Asn; XPD Lys751Gln) SNPs. Analysis involved Kaplan-Meier curves, log-rank tests, and Cox proportional hazards models. Results: Median age: 63 years (range 28–80); 91% male; 100% ECOG performance status (PS) 0–1; adenocarcinoma 79%; stages IIA 22%, IIB 30%, III 33%, and IVA 15%. No SNPs were associated with stage or PS. Multiple NER SNP was independently prognostic for OS and DFS (see Table ). When compared to individuals who were wildtype in all four studied NER SNPs, individuals with variants in all four NER SNPs were associated with substantial improvement in OS (Adjusted Hazard Ratio (AHR) = 0.40, 95% confidence interval (CI) = 0.2–0.7) and DFS (AHR = 0.44, 95%CI = 0.2–0.8). Furthermore, increasing numbers of variant genotypes were associated with a progressive increase in OS &amp; DFS when all seven NER/BER pathway SNPs were analysed together ( Table ). There was a 3.8- fold increase in OS (75 vs. 20 months) and five-fold increase in DFS (51 vs. 10 months) when comparing individuals with 6–7 SNPs with variant alleles to individuals with 0–1 SNPs with variant alleles. Conclusions: The ERCC1 8092 C/A, XPD Asp312Asn &amp; XPD Lys751Gln SNPs in the NER pathway are associated individually with prognosis in esophageal cancer patients treated with cisplatin-based trimodality regimens. In addition, as the number of NER and BER SNPs carrying variant alleles increased, OS and DFS improved dramatically. [Table: see text] No significant financial relationships to disclose.

Polymorphisms in base-excision repair and nucleotide-excision repair genes in relation to lung cancer risk

Polymorphisms in DNA repair genes may be associated with differences in DNA repair capacity, thereby influencing the individual susceptibility to smoking-related cancer. We investigated the association of 10 base-excision and nucleotide-excision repair gene polymorphisms ( XRCC1 −77 T/C, Arg194Trp, Arg280His and Arg399Gln; APE1 Asp148Glu; OGG1 Ser326Cys; XPA −4 G/A; XPC PAT; XPD Asp312Asn and Lys751Gln) with lung cancer risk in Caucasians. Genotypes were determined by PCR–RFLP and PCR-single base extension assays in 110 lung cancer patients and 110 age- and sex-matched controls, and the results were analyzed using logistic regression adjusted for relevant covariates. A significant association between the APE1 Asp148Glu polymorphism and lung cancer risk was found, with adjusted odds ratios (OR) of 3.38 ( p = 0.001) for the Asp/Glu genotype and 2.39 ( p = 0.038) for the Glu/Glu genotype. Gene–smoking interaction analyses revealed a statistically significant interaction between cumulative cigarette smoking and the XRCC1 Arg399Gln and XPD Lys751Gln polymorphisms: these polymorphisms were significantly associated with lung cancer in nonsmokers and light smokers (<25 PY; OR = 4.92, p = 0.021 for XRCC1 399 Gln/Gln; OR = 3.62, p = 0.049 for XPD 751 Gln/Gln), but not in heavy smokers (≥25 PY; OR = 0.68, p = 0.566 for XRCC1 399 Gln/Gln; OR = 0.46, p = 0.295 for XPD 751 Gln/Gln). Both the XRCC1 Arg194Trp and Arg280His as well as the OGG1 Ser326Cys heterozygous genotypes were associated with a significantly reduced risk for lung cancer (OR = 0.32, p = 0.024; OR = 0.25, p = 0.028; OR = 0.51, p = 0.033, respectively). No associations with lung cancer risk were found for the XRCC1 −77 T/C, the XPA −4 G/A and the XPC PAT polymorphisms. In conclusion, the APE1 Asp148Glu polymorphism is highly predictive for lung cancer, and cumulative cigarette smoking modifies the associations between the XRCC1 Arg399Gln and the XPD Lys751Gln polymorphisms and lung cancer risk.

Susceptibility to arsenic-induced skin lesions from polymorphisms in base excision repair genes

Genetic polymorphisms in the base excision DNA repair pathway may influence individual susceptibility to arsenic and the development of arsenic-induced skin lesions. Data from a case-control study of 792 cases and 792 matched controls conducted in Bangladesh from 2001 to 2003 were analyzed using conditional logistic regression to assess the associations between four common base excision repair (BER) genetic polymorphisms X-ray repair cross-complementing group 1 (XRCC1) Arg399Gln, XRCC1 Arg194Trp, human 8-oxoguanine DNA glycosylase (hOGG1) Ser326Cys and apurinic/apyrimidinic endonuclease (APE1) Asp148Glu and arsenic-induced skin lesions including melanosis and keratosis. Adjusted for toenail arsenic, body mass index, education, smoking and betel nut use, individuals with the APE1 148Glu/Glu polymorphism had a 2-fold increased odds of skin lesions compared with individuals with the 148Asp/Asp genotype (1.93; 95% confidence interval 1.15, 3.19). Gene-environment interactions between toenail arsenic and XRCC1 Arg194Trp and APE1 Asp148Glu were observed. Within the lowest arsenic tertile, APE1 148Glu/Glu had 2.5 times the odds ratio compared with wild-type, whereas within the highest tertile of arsenic the odds ratios for skin lesions did not differ. In contrast, at low arsenic levels, the odds ratios for skin lesions did not differ much by XRCC1 Arg194Trp genotype. However, at the highest tertile of arsenic, the XRCC1 194Arg/Arg polymorphism conferred a 3-fold larger odds ratio for skin lesions compared with XRCC1 194Trp/Trp. Individuals may have different odds for developing skin lesions based in part on their genetic profile for BER and their arsenic exposure history. Future research on arsenic-induced skin lesions should consider the impact of genetic variation to individual susceptibility to arsenic toxicity.

Association between Polymorphisms in the DNA Repair Genes, XRCC1, APE1, and XPD and Acute Side Effects of Radiotherapy in Breast Cancer Patients

Several DNA repair gene polymorphisms have been described, which affect DNA repair capacity and modulate cancer susceptibility. We evaluated the association of six polymorphisms in the DNA repair genes: XRCC1 (Arg194Trp, Arg280His, and Arg399Gln), APE1 (Asp148Glu), and XPD (Lys751Gln and Asp312Asn), with the risk of acute skin reactions following radiotherapy. We conducted a prospective study of 446 female patients with breast cancer who received radiotherapy after breast-conserving surgery. Individual genetic polymorphisms were determined using melting point analysis of sequence-specific hybridization probes. The development of acute skin reactions (moist desquamation) associated with DNA repair gene polymorphisms was modeled using Cox proportional hazards, accounting for cumulative biologically effective radiation dose. Overall, the development of acute toxicity, which presented in 77 patients, was not associated with the genetic variants studied, although the hazard ratios (HR) were generally below 1. Risks were however differential by body mass index. Among normal-weight patients only, both carriers of the APE1 148Glu and the XRCC1 399Gln alleles had decreased risk of acute skin reactions after radiotherapy (HR, 0.49 and 0.51, respectively). The results for XRCC1 were confirmed by haplotype analysis. When considering joint effects, we observed that compared with homozygote carriers of the wild-type allele in both genes, the risk was most strongly reduced in carriers of both APE1 148Glu and XRCC1 399Gln alleles with normal weight [HR, 0.19; 95% confidence interval (95% CI), 0.06-0.56] but not in those with overweight (HR, 1.39; 95% CI, 0.56-3.45; Pinteraction = 0.009). The XRCC1 399Gln or APE1 148Glu alleles may be protective against the development of acute side effects after radiotherapy in patients with normal weight.

Polymorphisms in DNA repair genes as risk factors for spina bifida and orofacial clefts

Repairing DNA damage is critical during embryogenesis because development involves sensitive periods of cell proliferation, and abnormal cell growth or death can result in malformations. Knockout mouse experiments have demonstrated that disruption of DNA repair genes results in embryolethality and structural defects. Studies using mid-organogenesis rat embryos showed that DNA repair genes were variably expressed. It is hypothesized that polymorphisms that alter the functionality of DNA repair enzymes may modify the risk of malformations. We conducted a case-control analysis to investigate the relationship between DNA repair gene polymorphisms and the risk of spina bifida and oral clefts. Newborn screening blood spot DNA was obtained for 250 cases (125 spina bifida, 125 oral clefts) identified by the California Birth Defects Monitoring Program, and 350 non-malformation controls identified from birth records. Six single nucleotide polymorphisms of five DNA repair genes representing three distinct repair pathways were interrogated including: XRCC1 (Arg399Gln), APE1 (Asp148Glu), XRCC3 (Thr241Met), hOGG1(Ser326Cys), XPD (Asp312Asn, Lys751Gln). Elevated or decreased odds ratios (OR, adjusted for race/ethnicity) for spina bifida were found for genotypes containing at least one copy of the variant allele for XPD [751Gln, OR = 1.62; 95% confidence interval (CI) = 1.05-2.50] and APE 148 (OR = 0.58; CI = 0.37-0.90). A decreased risk of oral clefts was found for XRCC3 (OR = 0.62; CI = 0.39-0.99) and hOGG1 (326 Cys/Cys, OR = 0.22; CI = 0.06-0.78). This study suggested that polymorphisms of DNA repair genes, representing different major repair pathways, may affect risk of two major birth defects. Future, larger studies, examining additional repair genes, birth defects, and interaction with exposures are recommended.

Amino acid substitution variants of APE1 and XRCC1 genes associated with ionizing radiation sensitivity.

Although several variants of DNA repair genes have been identified, their functional significance has not been determined. Using samples collected from 135 cancer-free women, this study evaluated whether amino acid substitution variants of DNA repair genes contribute to ionizing radiation (IR) susceptibility as measured by prolonged cell cycle G2 delay. PCR-restriction fragment length polymorphism (RFLP) assays were used to determine four genotypes: X-ray repair cross complementing group 1 (XRCC1, exon 6, C/T, 194 Arg/Trp and exon 10, G/A, 399 Arg/Gln), XRCC group 3 (XRCC3, exon 7, C/T, 241 Thr/Met) and apurinic/apyrimidinic endonuclease 1 (APE1, exon 5, T/G, 148 Asp/Glu). Fluorescence-activated cell sorter (FACS) analysis was used to measure cell cycle delay. APE1 (exon 5) genotype was significantly associated with mitotic delay (P = 0.01), with the Glu/Glu genotype having prolonged delay compared with the other two genotypes. The mitotic delay index (mean +/- SD) in women with the APE1 codon 148 Asp/Asp, Asp/Glu and Glu/Glu genotypes was 30.95 +/- 10.15 (n = 49), 30.65 +/- 10.4 (n = 60) and 39.56 +/- 13.12 (n = 21), respectively. There was a significant interaction between family history (FH) and APE1 (exon 5) genotype (P = 0.007) as well as FH and XRCC1 (exon 10) genotype (P = 0.005) in mitotic delay. Lastly, prolonged cell cycle delay was significantly associated with number of variant alleles when APE1 Asp148Glu and XRCC1 Arg399Gln genotypes were evaluated in a four-level model (chi(2) for linear trend = 10.9; P = 0.001). These results suggest that amino acid substitution variants of XRCC1 and APE1 may contribute to IR hypersensitivity.