Grantee Research Project Results
2005 Progress Report: Analysis of Genotoxic Biomarkers in Children Associated with a Pediatric Cancer Cluster and Exposure to Two Superfund Sites
EPA Grant Number: CR830757Title: Analysis of Genotoxic Biomarkers in Children Associated with a Pediatric Cancer Cluster and Exposure to Two Superfund Sites
Investigators: Finette, Barry A. , O'Neill, J. Patrick , Vacek, Pamela
Current Investigators: Finette, Barry A.
Institution: University of Vermont
EPA Project Officer: Aja, Hayley
Project Period: March 1, 2003 through February 28, 2006 (Extended to December 31, 2007)
Project Period Covered by this Report: March 1, 2005 through February 28, 2006
Project Amount: $775,141
RFA: Children's Vulnerability to Toxic Substances in the Environment (2002) RFA Text | Recipients Lists
Research Category: Children's Health , Human Health
Objective:
The objective of this research project is to evaluate the utility of specific biomarkers of effect and susceptibility for studying cancer risk in children following genotoxic exposures. We are determining if children from an exposed population with elevated cancer incidence have an increase in chromosome aberrations or changes in hypoxanthine-guanine phosphoribosyl transferase (HPRT) mutational spectrum, such as: (1) an increase in frameshift mutations reflective of exposure to anthraquinone-based dyes and styrene-acrylonitrile trimers; (2) an increase in point mutations reflective of exposure to benzidine-based dyes, epichlorohydrin and trichloropropane; and (3) an increase in V(D)J recombinase-mediated deletions reflective of exposure to aromatic hydrocarbons. We also are determining if specific DNA polymorphisms in 11 carcinogen metabolizing and DNA repair enzymes are associated with increased mutagenic susceptibility to genotoxic exposure.
Progress Summary:
Our approach is to analyze biomarkers of effect and susceptibility in exposed siblings of children in a Centers for Disease Control and Prevention-defined pediatric cancer cluster that has been linked to transplacental and childhood exposure to contaminated groundwater from two U.S. Environmental Protection Agency-designated Superfund sites in Dover Township, New Jersey. Exposure studies are focusing on the siblings of children with cancer rather than the children with cancer because of the genotoxic effects of cancer treatment. Biomarkers of susceptibility, however, are being measured in children with cancer. Biomarkers of effect (chromosomal aberrations and HPRT mutations) in the exposed siblings are being compared to measurements in unexposed children from neighboring communities. Biomarkers of susceptibility (DNA polymorphisms for carcinogen metabolizing enzymes) in the exposed siblings and unexposed children are being compared to children with cancer to determine if the latter have a higher prevalence of specific metabolic genotypes. In addition, the relationships between biomarkers of effect and susceptibility in exposed siblings and unexposed children are being examined to see if the effects of exposure are modified by any of these metabolic polymorphisms. Exposures in all subjects will be evaluated from their residential and personal histories, using a computer model developed by the Agency for Toxic Substances and Disease Registry (ATSDR) to estimate exposure to different water sources over time.
We have completed and published our HPRT cloning assay analysis that measured the frequency of somatic mutations (MFs) in 49 exposed siblings and 43 age/gender matched unexposed children (Vacek, et al., 2005). These studies demonstrated that the frequency of MFs in peripheral T-cells from these children were not significantly different regardless of whether results were adjusted or unadjusted for age and CE (Residual lnMF). The fact that HPRT lnMF and residual lnMF were not significantly different does not preclude that significant genotoxic differences exist at the genomic level that would be reflected in a change in the mutational spectrum.
To date, we have completed the mutational analysis of 225/376 (60%) mutant T-cell isolates from 89 of the 91 individuals. The remaining 151 mutant isolates are at various stages of completion. Although this analysis is blinded, we are not able to perform our comparative spectrum analysis between our test groups until the spectra analysis has been completed and the identification numbers are decoded. We do continue to observe a significant number of deletions and transversion at splice site locations. There also continues to be evidence of an increased clonality of mutational events in this group as well. We are making good progress in our chromosomal aberration studies in exposed and unexposed children as a determinant of widespread genomic damage following genotoxic exposure and cancer risk. Based on better than predicted metaphase spreads, we elected to increase the number of metaphases analyzed per subject to 1,500 from our original goal of 1,000 per subject. This will increase significantly the sensitivity of this analysis.
We were able to obtain high quality metaphase spreads and performed fluorescence in situ hybridization (FISH) on 88 of 91 (97%) subjects. To date we have completed our FISH chromosome aberration analysis on 35 of 88 (40%) subjects. We are not able to perform our comparative analysis until the FISH analysis has been completed and the identification numbers are decoded as this analysis also is double-blinded.
During Year 3, we continued the recruitment of peripheral blood samples from affected siblings with cancer of those subjects outlined in specific aims 1-3. This recruitment was done in cooperation with members of the group Toxic Environment Affects Children’s Health from Toms River, New Jersey. We have recruited a total of 33 peripheral blood samples from this cohort for the comparative polymorphism frequency analysis of 26 polymorphisms in 13 metabolic genes. To date, we have analyzed 7 polymorphisms from 121 subjects. Analysis at the epoxide hydrolase 1 (T/C: Tyr113His) locus revealed a statistically significant association with the number of copies of the C-allele in the exposed Toms River cancer cases. Although the remaining polymorphisms analyzed to date showed no statistically significant difference in prevalence, likely caused by limited power, there are a number of potentially important observations. The Neg/Neg genotype for the glutathione S-transferase theta 1 (GSTT1) deletion polymorphism occurred in 27.6 percent of the exposed cancer cases, compared to 18.4 percent in the siblings and 16.3 percent in healthy controls. The Pos/Pos GSTT1 genotype occurred in 34.5 percent of the exposed cancer cases, compared to 46.9 percent of siblings. N-acetyltransferase 2 polymorphisms (T341C C/C; A803G G/G; G857A G/A) were all higher in the exposed cancer cases compared to exposed noncancer siblings. Continued analysis will determine the utility of metabolic polymorphisms as biomarkers for pediatric cancer risk following genotoxic exposure.
We hope to be able to recruit an additional 10 subjects for this analysis to increase our sensitivity to these polymorphisms. In addition, we have developed and tested our questionnaire for obtaining information about all residences and schools attended by the study participants, to enable us to estimate potential exposure to contaminated drinking water for individual subjects. The questionnaire also contains questions regarding other potential exposures to genotoxic substances by both the participant and his/her mother during pregnancy. We obtained final Institutional Review Board approval of the questionnaire and have compiled all the necessary contact information (addresses and telephone numbers) for study subjects with the assistance of members of the Citizens Action Committee on the Childhood Cancer Cluster of Toms River.
Future Activities:
During our unfunded extension, we should complete the double blind mutational spectra analysis of five mutants from each subject as outlined for Objective 2. We also should complete the FISH analysis for chromosomal aberrations as described for Objective 3. We anticipate the completion of the polymorphism and all the statistical analysis for these studies as well. We will perform our analysis with the ATSDR Historical Reconstruction of the Water-Distribution System Serving the Dover Township Area, New Jersey, in preparation for determining exposures to differing water sources based on subjects residential history. These findings will be analyzed with those obtained from our other biomarker studies and appropriate manuscripts will be prepared.
Journal Articles on this Report : 1 Displayed | Download in RIS Format
Other project views: | All 12 publications | 1 publications in selected types | All 1 journal articles |
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Type | Citation | ||
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Vacek PM, Messier T, Rivers J, Sullivan L, O'Neill JP, Finette BA. Somatic mutant frequency at the HPRT locus in children associated with a pediatric cancer cluster linked to exposure to two Superfund sites. Environmental and Molecular Mutagenesis 2005;45(4):339-345. |
CR830757 (2004) CR830757 (2005) CR830757 (2006) CR830757 (Final) |
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Supplemental Keywords:
biomarkers, drinking water, risk assessment, human health, infants, children, genetic pre-disposition, hydro-geology, northeast, industry, vulnerability, sensitive population, genetics,, RFA, Health, Scientific Discipline, ENVIRONMENTAL MANAGEMENT, Health Risk Assessment, Risk Assessments, Susceptibility/Sensitive Population/Genetic Susceptibility, Children's Health, genetic susceptability, Risk Assessment, developmental neurotoxicology, neurotoxic, sensitive populations, pediactric cancer, childhood cancer, biomarkers, computer models, developmental effects, genotoxic biomarkers, Human Health Risk Assessment, children, assessment of exposure, children's vulnerablity, residential populations, neurodevelopmental toxicity, human exposure, neurobehavioral effects, contaminated groundwater, biological markers, toxicsProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.