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Final Report: Conformational Protein Effects of Environmental Mutagens
EPA Grant Number: R826685Title: Conformational Protein Effects of Environmental Mutagens
Investigators: Brandt-Rauf, Paul
Institution: Columbia University
EPA Project Officer: Deener, Kacee
Project Period: October 1, 1998 through September 30, 2001
Project Amount: $388,644
RFA: Exploratory Research - Human Health (1998)
Research Category: Health Effects
Description:
Objective:The objective of this research was to test the hypothesis that eight different environmentally induced mutations in the p53 tumor suppressor gene produce common conformational changes in the encoded p53 proteins. This was accomplished by conformational energy analysis and molecular dynamics simulations with confirmation by immunohistochemistry of tumor samples known to contain the given mutations, using monoclonal antibodies for epitopes of the p53 protein coincident with the predicted regions of common conformational change. Regions of common conformational change were investigated as potential biomarkers for the effects of exposure to environmental mutagens, based on identification of epitopes by monoclonal antibodies, which could be used in the refinement of environmental cancer risk assessment. Regions of common conformational change also were investigated as potential "effector domains" that could be targets for the development of preventive interventions, based on competitive inhibition with corresponding peptide sequences, to nullify the effects of environmental mutations. Summary/Accomplishments (Outputs/Outcomes):
Conformational energy analysis and molecular dynamics simulations of the structure of p53 with eight different environmentally induced mutations demonstrated that all of the mutants share areas of common conformational change consistent with prior results and with experimental results of tumor immunohistochemistry of conformationally altered epitopes. In addition, there are other areas of conformational change that are shared by some, but not all, mutants examined (Chen, et al., 1999, 2001).
The three different mutations in p53 produced by vinyl chloride were found to produce several different common conformational changes that could potentially serve as biomarkers of effect from the exposure. One of these common conformational changes was examined as such a biomarker in a cohort of workers exposed to vinyl chloride, and the occurrence of the biomarker was found to be highly statistically significantly correlated with the level of vinyl chloride exposure. This relationship remained significant even for the occurrence of combinations of different vinyl chloride-induced biomarkers in the same individual down to a cumulative level of exposure that would be the equivalent of one-quarter of the current permissible exposure limit, but not at exposures below that, suggesting that the current risk assessment for such exposures may be inadequate and may be improved by the incorporation of such biomarkers based on mutationally induced conformational change (Brandt-Rauf, et al., 2001).
In addition, regions of the mutant proteins that have been identified as undergoing common conformational changes have been investigated as potential "effector domains" of p53 function. Based on prior experience, such flexible regions are in many cases involved in critical interactions of the protein with other cellular elements through which the protein induces its functional effects. In this case, it has been possible to demonstrate through molecular dynamics modeling that one such region in p53 probably interacts with another region of p53, and that both regions act as regulatory domains for the protein's apoptotic function. Peptides corresponding to one of these regions have been synthesized and shown to induce apoptosis of cancer cells in culture that contain p53 mutants (but not in normal cells that contain wild-type p53) by disrupting the interaction between these regulatory domains (Kim, et al., 1999). A synthetic peptide designed by conformational energy analysis from another region of p53 also has been found to induce necrosis in cancer cells (but not in normal cells) independent of established mechanisms of p53 action, perhaps by interacting with and disrupting membrane proteins (Kanovsky, et al., 2001).
Different environmentally induced mutations in p53 can produce common conformational changes in the protein. Some of these identified regions of common change can serve as potential biomarkers of the effects of environmental mutagens in exposed humans, which can be used to refine the risk assessment for these exposures. In addition, peptides from various regions of p53 identified by molecular dynamics or conformational energy analysis can selectively kill cancer cells in culture and, thus, could serve as prototypes for chemotherapy and/or chemoprophylaxis in individuals at risk for cancer due to environmentally induced mutations.
Journal Articles on this Report: 4 Displayed | Download in RIS Format
| Other project views: | All 5 publications | 4 publications in selected types | All 4 journal articles |
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Brandt-Rauf PW, Luo JC,Cheng TJ, Du CL, Wang JD, Rosal R, Do T, Marion MJ. Molecular Biomarkers and Epidemiologic Risk Assessment. Human and Ecological Risk Assessment 2000;8(6):1295-1301. |
R826685 (Final) |
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Chen JM, et al. Common conformational effects in the p53 protein of vinyl chloride-induced mutations. Journal of Protein Chemistry 1999;18:467-472. |
R826685 (2000) R826685 (Final) |
not available |
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Chen JM, Rosal R, Smith S, Pincus MR, Brandt-Rauf PW. Common conformational effects of p53 mutations. Journal of Protein Chemistry 2001;20(2):101-105. |
R826685 (Final) |
not available |
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Kim AL, Raffo AJ, Brandt-Rauf PW, Pincus MR, Monaco R, Abarzua P, Fine RL. Conformational and molecular basis for induction of apoptosis by a p53 C-terminal peptide in human cancer cells. Journal of Biological Chemistry 1999;274(34):924-931. |
R826685 (2000) R826685 (Final) |
not available |
p53, tumor suppressor gene, protein, mutants, mutations, immunohistochemistry, antibodies. , Scientific Discipline, Health, RFA, Risk Assessments, Disease & Cumulative Effects, Health Risk Assessment, cancer risk, biomarkers, cancer risk assessment, health effects, multi-pollutant analyses, environmentally induced mutations, carcinogens, conformational protein, biological markers, immunohistochemistry, cell biology, indicators, molecular characterization, environmental stressors, human exposure
Progress and Final Reports:
2000 Progress Report
Original Abstract