Biomedical subjects

R M Santella

Publications and source records attributed to R M Santella.

At least 19 recordsLinked to original sources

PubMed2006

Hint1 is a haplo-insufficient tumor suppressor in mice.

The HINT1 protein, a member of the histidine triad (HIT) family, is highly conserved in diverse species and ubiquitously expressed in mammalian tissues. However, its precise function in mammalian cells is not known. As a result of its structural similarity to the tumor-suppressor protein FHIT, we used homozygous-deleted Hint1 mice to study its role in tumorigenesis. We discovered that after 2 to 3 years of age the spontaneous tumor incidence in Hint1 -/- mice was significantly greater than that in wild-type Hint1 +/+ mice (P < 0.05). Using a well-established mouse model of 7,12-dimethylbenz[a]anthracene (DMBA)-induced mammary carcinogenesis we found a marked and significant (P < 0.05) increase in the incidence of mammary and ovarian tumors in both, Hint1 -/- and +/- mice versus +/+ mice. The Hint1 -/- and +/- mice had similar tumor incidence and similar tumor histologies. Therefore, deletion of Hint1 in mice enhances both spontaneous tumor development and susceptibility to tumor induction by DMBA. In addition, since the Hint1 +/- tumors retained expression of the unmutated wild-type allele, Hint1 is haplo-insufficient with respect to tumor suppression in this model system.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed2002

Determinants of formation of aflatoxin-albumin adducts: a seven-township study in Taiwan.

Dietary exposure to aflatoxins is one of the major risk factors for hepatocellular carcinoma. Individual susceptibility to aflatoxin-induced hepatocarcinogenesis may be modulated by both genetic and environmental factors affecting metabolism. A cross-sectional study was performed to evaluate determinants of the formation of aflatoxin covalently bound to albumin (AFB1-albumin adducts). A total of 474 subjects who were free of liver cancer and cirrhosis and were initially selected as controls for previous case-control studies of aflatoxin-induced hepatocarcinogenesis in Taiwan, were employed in this study. Aflatoxin-albumin adducts were determined by competitive enzyme-linked immunosorbent assay, hepatitis B surface antigen and antibodies to hepatitis C virus by enzyme immunoassay, as well as genotypes of glutathione S-transferase M1-1 and T1-1 by polymerase chain reaction. The detection rate of AFB1-albumin adducts was significantly higher in males (42.5%) than in females (21.6%) (multivariate-adjusted odds ratio=2.6, 95% confidence interval=1.4-5.0). The formation of detectable albumin adducts was moderately higher in hepatitis B surface antigen carriers (42.8%) than in non-carriers (36.6%) (multivariate-adjusted odds ratio=1.4, 95% confidence interval=1.0-2.1). In addition, the detection rate of AFB1-albumin adducts tended to increase with the increasing number of null genotypes of glutathione S-transferase M1-1 and glutathione S-transferase T1-1. In conclusion, this cross-sectional study has assessed the relative contributions of environmental exposure and host susceptibility factors in the formation of AFB1-albumin adducts in a well characterised Chinese adult population. This study further emphasises the necessity to reduce aflatoxin exposure in people living in an area endemic for chronic hepatitis B virus infection.

Adult↗

PubMed2001

Molecular epidemiologic studies within the Selenium and Vitamin E Cancer Prevention Trial (SELECT).

OBJECTIVE: To conduct timely epidemiologic investigations of molecular/genetic markers that may contribute to the development of prostate, lung, colorectal, or other cancers within the Selenium and Vitamin E Cancer Prevention Trial (SELECT), and to evaluate interactions between these markers and the study interventions. METHODS: The epidemiologic studies within SELECT will be based on 32,400 men aged 55 years or older (age 50 or older for the African-American men) enrolled into an intergroup, randomized, placebo-controlled, double-blind, phase III prevention trial of supplemental selenium and vitamin E developed and funded by the National Cancer Institute, and coordinated by the Southwest Oncology Group. During the 12-year study period approximately 1500-2000 cases of prostate cancer, 800 lung cancers, and 500 colon cancers are estimated to be diagnosed, based on data from the ongoing Prostate Cancer Prevention Trial of finasteride. A modified fasting blood sample will be processed to collect plasma for analysis of micronutrients, hormones, cytokines, and other proteins. Buffy-coat derived white blood cells collected at baseline will be used for isolation of DNA and establishment of immortalized cell lines. Red blood cells will be stored for analysis of hemoglobin adducts and other components. RESULTS: Specific results anticipated from these molecular studies will provide information on factors hypothesized to contribute to prostate cancer risk and that may modify the efficacy of either trial supplement, including: steroid sex hormones and several polymorphic genes that encode proteins affecting androgenic stimulation of the prostate, including the androgen receptor, steroid 5alpha-reductase type II, CYP17, and beta-hydroxysteroid dehydrogenase; polymorphisms of DNA repair genes and carcinogen metabolism genes, including those involved in the activation of chemical carcinogens to reactive intermediates (e.g., CYP1A1) or the detoxification of reactive intermediates (e.g., glutathione S-transferase M1); DNA and protein adducts; and insulin-like growth factors and leptin. CONCLUSION: SELECT offers an excellent opportunity to conduct molecular epidemiologic investigations to assess gene-environment interactions and their role in prostate, lung, and colon carcinogenesis.

Colorectal Neoplasms↗

PubMed2001

Genetic polymorphisms of glutathione S-transferases M1 and T1 associated with susceptibility to aflatoxin-related hepatocarcinogenesis among chronic hepatitis B carriers: a nested case-control study in Taiwan.

This study was conducted to investigate the modifying effect of glutathione S-transferase (GST) M1 and T1 polymorphisms on aflatoxin-induced hepatocarcinogenesis among chronic hepatitis B virus surface antigen (HBsAg) carriers. A total of 79 HBsAg-positive cases of hepatocellular carcinoma (HCC) diagnosed between 1991 and 1997 were identified and individually matched to one or two HBsAg-positive controls on age, gender, residence and date of recruitment from the same cancer screening cohort in Taiwan. Blood samples were tested for hepatitis B and C viral markers by enzyme immunoassay and for aflatoxin B(1) (AFB(1))-albumin adducts by competitive enzyme-linked immunosorbent assay. GSTM1 and GSTT1 genotypes were determined by PCR. There was a statistically significant relationship between detectable levels of AFB(1)-albumin adducts in serum and risk of HCC among chronic HBsAg carriers, with an adjusted odds ratio (OR) of 2.0 [95% confidence interval (CI) 1.1-3.7]. In addition, the effect of aflatoxin exposure on HCC risk was more pronounced among chronic HBsAg carriers with the GSTT1 null genotype (OR 3.7, 95% CI 1.5-9.3) than those who were non-null (OR 0.9, 95% CI 0.3-2.4). The interaction between serum AFB(1)-albumin adduct level and GSTT1 genotype was statistically significant (P = 0.03). For GSTM1 the effect of aflatoxin exposure on HCC risk in those with the null genotype was also greater (adjusted OR 2.8, 95% CI 1.0-7.8) than in those with the gene present (adjusted OR 1.8, 95% CI 0.8-4.5), but the difference was not significant (P = 0.91). Notably, when the interaction between aflatoxin exposure and GSTT1 genotype was considered, aflatoxin exposure by itself was not a significant determinant of HCC risk among chronic HBsAg carriers. These results demonstrate the importance of gene-environment interactions in the multifactorial development of HCC.

Adult↗

PubMed2001

Variability in aflatoxin-albumin adduct levels and effects of hepatitis B and C virus infection and glutathione S-transferase M1 and T1 genotype.

Exposure to aflatoxin B1 (AFB1), an important cofactor in the etiology of hepatocellular carcinoma in Taiwan, is influenced by dietary and other factors. The present study examined the intraindividual variability in AFB1-albumin adducts, the most reliable long-term biomarker of AFB1 exposure, and whether the baseline or follow-up adduct levels and the intraindividual variability in adduct levels are modified by endogenous and environmental factors. The study measured AFB1-albumin adduct levels among 264 healthy male residents of three townships (Hu-Hsi, Ma-Kung, and Pai-Hsa) of Penghu Islets, Taiwan, at two different time points with a median interval of 1.68 years (range 1.00-3.17 years). There was a generalized reduction in the adduct levels, with the median values being 22.1 pmol/mg (range 5.0-355.8 pmol/mg) at time 1 and 14.3 pmol/mg (range 5.0-205.2 pmol/mg) at time 2. This intraindividual variability in adduct levels was inversely associated with the age of subjects and the time interval between the two blood draws. The variability in adduct levels was lower among subjects in Hu-Hsi and Pai-Hsa townships as compared to those in Ma-Kung. No significant association was observed for the intraindividual variability in AFB1-albumin adducts with regard to the season when blood was drawn. There was also no significant association between intraindividual variability and hepatitis B surface antigen, anti-hepatitis C virus (anti-HCV), glutathione S-transferase (GST) M1, or GSTT1 status. In conclusion, we found substantial intraindividual variability in the AFB1 exposure (as determined by AFB1-albumin adducts) in Taiwan, which was probably more likely related to dietary or other environmental influences rather than to endogenous factors (e.g., hepatitis B/C viral infection or GST M1/T1 genetic status).

Adult↗

PubMed2001

Biomarkers of polycyclic aromatic hydrocarbon-DNA damage and cigarette smoke exposures in paired maternal and newborn blood samples as a measure of differential susceptibility.

Human and experimental evidence indicates that the developing fetus may be more susceptible than the adult to the effects of certain carcinogens, including some polycyclic aromatic hydrocarbons (PAHs). Factors that can modulate susceptibility include proliferation rates, detoxification capabilities, and DNA repair capacity. Biomarkers can facilitate quantification of age-related susceptibility among human populations. In this study, we report on three biomarkers measured in paired blood samples collected at birth from 160 Polish mothers and newborns: 70 pairs from Krakow (a city with high air pollution including PAHs) and 90 pairs from Limanowa (an area with lower ambient pollution but greater indoor coal use). Biomarkers were: WBC aromatic-DNA adducts by (32)P-postlabeling and PAH-DNA adducts by ELISA (as indicators of DNA damage from PAHs and other aromatics) and plasma cotinine (as an internal dosimeter of cigarette smoke). Correlations were assessed by Spearman's rank test, and differences in biomarker levels were assessed by the Wilcoxon signed-ranks test. A significant correlation between paired newborn/maternal samples was seen for aromatic-DNA adduct levels (r = 0.3; P < 0.001) and plasma cotinine (r = 0.8; P < 0.001) but not PAH-DNA adduct levels (r = 0.14; P = 0.13). Among the total cohort, levels of the three biomarkers were higher in newborn samples compared with paired maternal samples. The difference was significant for aromatic-DNA adduct levels (16.6 +/- 12.5 versus 14.21 +/- 15.4/10(8) nucleotides; P = 0.002) and plasma cotinine (14.2 +/- 35.5 versus 8.3 +/- 24.5 ng/ml; P < 0.001) but not for PAH-DNA adduct levels (7.9 +/- 9.9 versus 5.9 +/- 8.2/10(8) nucleotides; P = 0.13). When analyses were restricted to the 80 mother/newborn pairs from whom the blood sample was drawn concurrently (within 1 h of each other), levels of all of the three biomarkers were significantly higher in the newborn compared with paired maternal blood samples (P < 0.05). Results suggest reduced detoxification capabilities and increased susceptibility of the fetus to DNA damage, especially in light of experimental evidence that transplacental exposures to PAHs are 10-fold lower than paired maternal exposures. The results have implications for risk assessment, which currently does not adequately account for sensitive subsets of the population.

Adult↗

PubMed2001

Immunoperoxidase detection of polycyclic aromatic hydrocarbon-DNA adducts in breast tissue sections.

Although the etiology of the majority of human breast cancers is unknown, environmental carcinogens are suspected to play a role. In this study, we investigated polycyclic aromatic hydrocarbon-DNA adducts in 78 breast cancer patients and benign breast disease patients with lifetime environmental exposure to polycyclic aromatic hydrocarbon (PAH) compounds. Adducts were detected in paraffin sections by immunoperoxidase method using polyclonal antiserum and were quantitated by the image-analyzing system. A significantly higher level of adducts was found in benign breast disease as compared to cancer patients (P < .001; Mann-Whitney U test). Neither smoking nor genetic polymorphisms in glutathione S-transferase and cytochrome P450 influenced the level of adducts. This exploratory study demonstrates the usefulness of the immunoperoxidase method to detect PAH-DNA adducts in stored breast tissue and suggests further research on a larger population, including patients from both high- and low-pollution environments.

Adult↗

PubMed2001

Association of aflatoxin B(1)-albumin adduct levels with hepatitis B surface antigen status among adolescents in Taiwan.

Chronic hepatitis B virus (HBV) infection and aflatoxin B(1) (AFB(1)) exposure interact synergetically to induce hepatocellular carcinoma. One suggested mechanism for this interaction is the enhanced activation of AFB(1) in chronically HBV-infected individuals. Whereas no associations between chronic HBV infection and AFB(1)-albumin adducts were observed in several studies in adults, hepatitis B surface antigen (HbsAg)-positive children were found to have elevated adducts in Gambia. To assess the association between chronic HBV infection and AFB(1)-albumin adduct level in Taiwan, 200 junior high school adolescents from 20 townships were assayed for HBsAg and AFB(1)-albumin adducts. The mean AFB(1)-albumin adduct level was higher in HBsAg-positive compared with HBsAg-negative subjects. The association between HBsAg status and AFB(1)-albumin adducts remained after multivariate adjustment. This finding additionally supports the synergetic interaction between HBV and AFB(1), but the mechanism remains to be elucidated.

Adolescent↗

PubMed2000

Antioxidant enzyme expression and reactive oxygen species damage in prostatic intraepithelial neoplasia and cancer.

BACKGROUND: Oxidative stress results in damage to cellular structures and has been linked to many diseases, including cancer. The authors sought to determine whether the expression of three major antioxidant enzymes, copper-zinc superoxide dismutase (SOD1), manganese superoxide dismutase (SOD2), and catalase, was altered in human prostate carcinoma and its likely precursor, high grade prostatic intraepithelial neoplasia (PIN). The level of reactive oxygen species damage was evaluated by measuring the expression of the DNA adduct 8-hydroxydeoxyguanosine. METHODS: The authors evaluated the tissue expression of the antioxidant enzymes in prostate carcinoma by immunohistochemistry, immunogold electron microscopy, and enzymatic assay. The polymerase chain reaction was used to amplify and screen tissue specimens for the genes of SOD1, SOD2, and extracellular SOD (SOD3). Matched paraffin embedded tissue sections were evaluated by RNA in situ hybridization for expression of SOD1 and immunohistochemically for the DNA adduct 8-hydroxydeoxyguanosine. RESULTS: All prostatic tissues, including cancer, displayed immunoreactivity for the three antioxidant enzymes in epithelial cells, with no staining of the stroma, inflammatory cells, or endothelial cells. The number of immunoreactive cells was greater in benign epithelium than in PIN and cancer for each enzyme. The mean percentage and intensity of immunoreactive cells was greatest for SOD2, intermediate for SOD1, and lower for catalase. Staining in cancer was heterogeneous. Immunogold ultrasound studies revealed strong mitochondrial labeling for SOD2, which was greater in benign epithelium than in cancer; SOD1 labeling was invariably weaker, with nuclear labeling in benign epithelium and cytoplasmic labeling in cancer cells. There was no difference in enzyme activity for the three antioxidant enzymes between benign epithelium and cancer. No mutations were found in the 5 exons of SOD1, 5 exons of SOD2, and 3 exons of SOD3, except for 3 of 20 cases with polymorphisms for exon 3 of SOD1. Intense nuclear immunoreactivity for 8-hydroxydeoxyguanosine was present in fewer than 3% of epithelial cells, with no apparent differences among benign epithelium, PIN, and cancer. CONCLUSIONS: SOD1, SOD2, and catalase had lower expression in PIN and prostate carcinoma than in benign epithelium. The number of immunoreactive cells in PIN was similar to cancer, indicating that these are closely related. Enzyme activities were variable, with no difference between benign epithelial cells and cancer, although this lack of change in enzyme activity could have been due to the presence of contaminating benign cells within the cancer specimens. The results of reactive oxygen species damage were found only in the epithelium and not in the stroma. Expression of the DNA adduct 8-hydroxydeoxyguanosine was present in fewer than 3% of cells, with no apparent differences among benign epithelium, PIN, and cancer. These findings suggest that oxidative stress is an early event in carcinogenesis.

Aged↗

PubMed2000

Immunohistochemical analysis of polycyclic aromatic hydrocarbon-DNA adducts in breast tumor tissue.

Environmental carcinogens may play a role in the etiology of breast cancer, but the extent of their contribution is not yet defined. The aims of this study were to determine whether polycyclic aromatic hydrocarbon (PAH)-DNA adducts could be detected in stored paraffin blocks of breast tumor tissue (n=147) with an immunoperoxidase technique and whether they correlated with smoking history and/or mutant p53 protein expression. There was no significant difference in mean relative nuclear staining intensity in non-smokers (444+/-90, n=75), ever smokers (435+/-91, n=72), and current smokers (456+/-98, n=35). In either current or ever smokers, PAH-DNA adducts were non-significantly elevated in those with greater compared with lower exposure in relation to age at started smoking, years of smoking, cigarettes per day, and pack years. DNA damage levels were not elevated in tissues with compared with those without mutant p53 protein expression. These data demonstrate that immunohistochemical methods can be used to monitor DNA damage levels in archived breast tissues.

Adult↗

PubMed2000

Cloning and characterization of DIP1, a novel protein that is related to the Id family of proteins.

Using human cyclin D1 as the "bait" in a yeast two-hybrid system, together with a HL60 cDNA library, we identified a novel human nuclear protein designated DIP1. This protein is expressed in a variety of cell types, and in fibroblasts its level remains constant throughout the cell cycle. However, the level of this protein increases severalfold during the differentiation of HL60 cells. The DIP1 protein can be phosphorylated in vitro by a cellular kinase and this activity reaches its maximum in extracts obtained from cells in the G1 phase of the cell cycle. DIP1 contains a helix-loop-helix motif but lacks an adjacent basic DNA-binding domain, thus resembling the Id family of proteins. The dip1 gene is located on human chromosome 16p11.2-12, a locus that is amplified in several types of human cancer. These results suggest that DIP1 may be involved in the control of gene expression and differentiation, but its precise function remains to be determined.

Amino Acid Sequence↗

PubMed2000

Determination of r-7,t-8,9,c-10-tetrahydroxy-7,8,9, 10-tetrahydrobenzo[a]pyrene in human urine by gas chromatography/negative ion chemical ionization/mass spectrometry.

r-7,t-8,9,c-10-Tetrahydroxy-7,8,9,10-tetrahydrobenzo[a]pyrene (trans-anti-BaP-tetraol) is the major hydrolysis product of r-7, t-8-dihydroxy-t-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (anti-BPDE), the principal ultimate carcinogen of the environmental pollutant benzo[a]pyrene (BaP). As part of a program to establish activation/detoxification profiles of urinary metabolites of BaP in humans, we developed a method for quantifying trans-anti-BaP-tetraol. Urine was collected from three groups of individuals exposed to BaP: psoriasis patients treated with a coal tar-containing ointment, steel workers, and smokers. [(2)H(12)]-trans-anti-BaP-tetraol was added to the urine as an internal standard. The urine was treated with beta-glucuronidase and sulfatase, and then the BaP-tetraols were enriched by reverse-phase and phenylboronic acid solid-phase extraction. The resulting fraction was treated with sodium hydride and methylmethane sulfonate to convert BaP-tetraols to the corresponding tetramethyl ethers (BaP-TME). The mixture was purified by normal-phase HPLC and analyzed by gas chromatography/negative ion chemical ionization/mass spectrometry with selected ion monitoring. [(13)CH(3)](4)-trans-anti-BaP-TME was used as an external standard. Ions at m/z 376, 380, and 388 were monitored for quantitation of trans-anti-BaP-TME, [(13)CH(3)](4)-trans-anti-BaP-TME, and [(2)H(12)]-trans-anti-BaP-TME, respectively. The instrumental detection limit was approximately 1 fmol of trans-anti-BaP-TME. trans-anti-BaP-tetraol (as trans-anti-BaP-TME) was detected in 20 of 20 individuals receiving coal tar therapy (mean, 16 fmol/mL of urine), 13 of 13 exposed steel workers (mean, 4.1 fmol/mL of urine), and nine of 21 cigarette smokers (mean, 0.5 fmol/mL of urine). The means in these groups were significantly different (P < 0.0001). The urine of steel workers was also analyzed for cis-anti-BaP-tetraol and cys-syn-BaP-tetraol, but neither was found. The results of this study provide a quantitative method for determination of parts per trillion levels of trans-anti-BaP-tetraol in human urine. Ultimately, this method can be employed as part of a phenotyping approach for assessing BaP metabolites in human urine.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗

PubMed2000

Effects of carcinogen-induced transcription factors on the activation of hepatitis B virus expression in human hepatoblastoma HepG2 cells and its implication on hepatocellular carcinomas.

To elucidate the molecular mechanisms involved in the action of common carcinogens, which can act as important cofactors in modulating hepatitis B virus-mediated hepatocellular carcinogenesis, we have investigated the influence of aflatoxin B(1) (AFB), a potent liver carcinogen, as well as benzo[a]pyrene (BP) and 4-aminobiphenyl (4-ABP), carcinogens in cigarette smoke, on the induction of various transcription factors in human hepatoblastoma HepG2 cells. DNA electrophoretic mobility shift assays were performed with nuclear extracts from HepG2 cells treated with 10 micromol/L AFB, 40 micromol/L BP, or 300 micromol/L 4-ABP for 6 and 24 hours. Eight- and 6-fold increases in nuclear transcription factor kappaB (NF-kappaB), and 5- and 10-fold increases in activated protein (AP-1) transcription factor were observed with 24 hours AFB and BP treatments, respectively, whereas 4-ABP treatment resulted in an approximately 4-fold induction of both NF-kappaB and AP-1. Moreover, 4-ABP gave the strongest NF-kappaB activation in 6 hours of treatment. Four- and 10-fold activation of stress protein was detected by a consensus heat shock factor (HSF) sequence binding probe, with AFB and BP treatments, respectively. DNA adducts were observed by immunoassays in HepG2 cells treated with AFB and BP but not with 4-ABP. Increased human hepatitis B virus (HBV) surface antigen (HBsAg) synthesis was detected in AFB- and BP-treated HepG2 cells following transfection with recircularized HBV DNA. These data suggest that certain carcinogen-induced transcription factors may influence viral carcinogenesis and initiate hepatocellular carcinomas (HCC).

Carcinogens↗

PubMed2000

Carcinogen macromolecular adducts and their measurement.

Damage to DNA induced by carcinogenic chemicals reflects exposure and is directly related to tumor formation, whereas modification of protein provides relatively precise dosimetry for stable adducts of proteins with a known half-life. Sophisticated methods for the detection and quantitation of DNA and protein adducts have been developed during the last approximately 25 years. For DNA adducts the most widely used methods include electrochemical detection, mass spectrometry, fluorescence and phosphorescence spectroscopy, immunoassays and immunohistochemistry and (32)P-post-labeling. Detection limits for quantitative assays are typically in the range of 1 adduct in 10(7) or 10(9) nucleotides. However, accelerator mass spectrometry, which is highly sophisticated but less accessible, has a detection limit of approximately 1 adduct in 10(12) nucleotides. Methods for the determination of protein adducts include immunoassay and a variety of elegant high-resolution mass spectrometry approaches. The detection limit of approximately 0.1 fmol for protein adducts, is based primarily on method specificity and the availability of large quantities of sample material. Using these highly sensitive methods a major achievement has been the biomonitoring of chemically exposed human populations. Validation of macromolecular adduct formation in humans has been predicated on studies in animal models. Adduct formation in humans appears to be indicative of molecular dosimetry and suggestive of increased human cancer risk. However, despite the large body of literature documenting DNA and protein adduct molecular dosimetry for many carcinogen exposures, the relationship between adduct formation and human cancer risk has been defined for only a few carcinogens. Thus, elucidation of this association remains a compelling challenge. For the future, integration of DNA and protein adduct measurements together with documentation of correlative and subsequent events, and host susceptibility factors, within the context of valid molecular epidemiologic study designs, will further our understanding of human disease mechanisms.

Biotransformation↗

PubMed2000

Associations of plasma aflatoxin B1-albumin adduct level with plasma selenium level and genetic polymorphisms of glutathione S-transferase M1 and T1.

Mortality from hepatocellular carcinoma (HCC) is extraordinarily high in Matzu, an island off the coast of Southeastern China. To investigate factors associated with plasma aflatoxin B1 (AFB1)-albumin adduct level, we studied 304 healthy adult residents from Matzu. AFB1-albumin adducts were determined by competitive enzyme-linked immunosorbent assay, hepatitis B surface antigen status by enzyme immunoassay, genotypes of glutathione S-transferase (GST) M1 and T1 by polymerase chain reaction, plasma selenium by atomic absorption spectrometry, and plasma retinol, alpha-tocopherol, alpha-carotene, and beta-carotene levels by high-performance liquid chromatography. Men had higher AFB1-albumin adduct levels than women. GSTM1-nonnull and GSTT1-null genotypes and low plasma selenium level were significantly associated with an increased level of AFB1-albumin adducts among men, whereas age was significantly correlated with adduct level among women. High intake of fermented beans was associated with an increased adduct level among men and women. The inverse associations between plasma selenium level and AFB1-albumin adducts were statistically significant among those with null genotypes of GSTM1 and GSTT1, but not among the nonnull genotypes. This study provides insight into the dietary and genetic factors influencing AFB1-albumin adduct formation in an isolated population with high liver cancer mortality.

Adult↗

PubMed2000

Association between polycyclic aromatic hydrocarbon-DNA adduct levels in maternal and newborn white blood cells and glutathione S-transferase P1 and CYP1A1 polymorphisms.

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants; a number are carcinogenic. Metabolic polymorphisms may modulate susceptibility to PAH-induced DNA damage and carcinogenesis. This study investigates the relationship between PAH-DNA adduct levels (in maternal and newborn WBCs) and two polymorphisms: (a) an MspI RFLP in the 3' noncoding region of cytochrome P4501A1 (CYP1A1); and (b) an A-->G transition in nucleotide 313 of glutathione S-transferase P1 (GSTP1), resulting in an ile105val substitution. CYP1A1 catalyzes the bioactivation of PAH; the CYP1A1 MspI RFLP has been associated with cancer of the lung. GSTP1 catalyzes the detoxification of PAH; the val allele has greater catalytic efficiency toward PAH diol epoxides. The study involves 160 mothers and their newborns from Poland. Regression models controlled for maternal smoking and other confounders. No association was seen between maternal adduct levels and either polymorphism, separately or combined. However, adduct levels were higher among newborns with the CYP1A1 MspI restriction site (heterozygotes and homozygotes combined) compared with newborns lacking the restriction site (P = 0.06). Adducts were higher among GSTP1 ile/val and ile/ile newborns compared with GSTP1 val/val newborns (P = 0.08). Adduct levels were 4-fold higher among GSTP1 ile/ile newborns having the CYP1A1 restriction site compared with GSTP1 val/val newborns who lacked the CYP1A1 restriction site (P = 0.04). This study demonstrates a significant combined effect of phase I and phase II polymorphisms on DNA damage from PAHs in fetal tissues. It illustrates the importance of considering interindividual variation in assessing risks of transplacental exposure to PAHs.

Adult↗

PubMed2000

Effects of a 6-month vitamin intervention on DNA damage in heavy smokers.

Because their formation is associated with tumor development in specific tissues, DNA adducts have potential usefulness as intermediate end points in chemoprevention studies. To determine the efficacy of a combination of antioxidant vitamins (vitamins C and E and beta-carotene), a randomized clinical trial was conducted among heavy smokers using DNA damage as the end point. Immunological methods were used to measure polycyclic aromatic hydrocarbon-DNA adducts and oxidative DNA damage (8-oxo or hydroxydeoxyguanosine) in mononuclear and oral cells. A total of 121 subjects were randomized to the 6-month intervention and received either vitamins or placebo. Dropout rates were higher in the placebo than in the vitamin group; 65% of subjects in the vitamin group, but only 47% in the placebo group, provided specimens at 6 months. Plasma levels of all three antioxidants rose significantly in the vitamin group but not in the placebo group. All four measures of DNA damage decreased in both groups; the between-group differences were not statistically significant. These data do not provide clear evidence that antioxidant vitamin intake prevents DNA damage. However, the study demonstrates that DNA damage is a useful end point in chemoprevention trials.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed1999

Role of oxyradicals in mutagenicity and DNA damage induced by crocidolite asbestos in mammalian cells.

Crocidolite, one of the most carcinogenic forms of asbestos, is mutagenic in cultured mammalian cells when assayed using a system that can detect multilocus deletions. In the present study, we examined the effect of buthionine sulfoximine (BSO) on mutation frequency and the formation of 8-hydroxydeoxyguanosine (8-OHdG) in human-hamster hybrid (A(L)) cells induced by crocidolite fibers in an attempt to determine the role of oxyradicals in mediating fiber mutagenesis. BSO, a competitive inhibitor of the enzyme gamma-glutamyl cysteine synthetase, depleted nonprotein sulfhydryls to <5% of control within 24 h at a nonmutagenic dose of 25 microM. In cells pretreated with BSO for 24 h, the mutation yield at the CD59 locus induced by a 4 microg/cm2 dose of crocidolite fibers was increased by more than 3-fold (P < 0.05). Using immunoperoxidase staining with a monoclonal antibody specific for 8-OHdG, we demonstrated that crocidolite fibers induced a dose-dependent increase in oxidative DNA damage in A(L) cells. Furthermore, addition of DMSO, a well-established hydroxyl radical (OH*) scavenger, dramatically suppressed 8-OHdG induction (P < 0.005). Our results definitely demonstrate that reactive oxygen species mediate fiber-induced DNA damage mutagenesis in A(L) cells in a concentration-dependent manner.

8-Hydroxy-2'-Deoxyguanosine↗