Hexavalent chromium (CrVI) is a toxic DNA-damaging agent with a well-documented exposure in a large number of occupations, and it is a common environmental contaminant. Cr(VI) is listed by the ATSDR and EPA as one of the top 20 high priority toxic agents. The final oxidative form of Cr in biological systems is Cr(lll) that produces several stable DNA adducts. We have recently found that Cr(III)-DNA adducts are one of the major causes of mutagenicity of Cr(VI). Our new data indicate that Cr-DNA adducts also play an important role in toxicity of Cr(VI). Toxic responses to Cr-DNA adducts were strongly dependent on the presence of a small group of proteins that bind to Cr-damaged chromatin. This proposal is designed to test our working hypothesis that cytotoxic effects of Cr-DNA adducts are caused by the formation of secondary DNA lesions generated as a result of the recognition and processing of adducts by damage sensory proteins. Biochemical approaches and cellular models with downregulated levels of damage-processing proteins will be used to gain evidence supporting the proposed hypothesis. We constructed a series of the retroviral siRNA-encoding vectors, which will allow us to examine the role of various proteins in the cytotoxic responses in the target primary human bronchial epithelial cells that have not been previously amenable to the mechanistic studies. The results of this work are expected to advance molecular understanding of Cr(VI) injury in the major target cells and to identify damage processing proteins that enhance toxicity of Cr-DNA modifications. ? ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute of Environmental Health Sciences (NIEHS)
Type
Research Project (R01)
Project #
5R01ES012915-04
Application #
7237826
Study Section
Alcohol and Toxicology Subcommittee 4 (ALTX)
Program Officer
Thompson, Claudia L
Project Start
2004-07-01
Project End
2009-05-31
Budget Start
2007-06-01
Budget End
2008-05-31
Support Year
4
Fiscal Year
2007
Total Cost
$309,365
Indirect Cost
Name
Brown University
Department
Pathology
Type
Schools of Medicine
DUNS #
001785542
City
Providence
State
RI
Country
United States
Zip Code
02912
Reynolds, Mindy F; Peterson-Roth, Elizabeth C; Bespalov, Ivan A et al. (2009) Rapid DNA double-strand breaks resulting from processing of Cr-DNA cross-links by both MutS dimers. Cancer Res 69:1071-9
Guttmann, David; Poage, Graham; Johnston, Tatiana et al. (2008) Reduction with glutathione is a weakly mutagenic pathway in chromium(VI) metabolism. Chem Res Toxicol 21:2188-94
Salnikow, Konstantin; Zhitkovich, Anatoly (2008) Genetic and epigenetic mechanisms in metal carcinogenesis and cocarcinogenesis: nickel, arsenic, and chromium. Chem Res Toxicol 21:28-44
Reynolds, Mindy; Zhitkovich, Anatoly (2007) Cellular vitamin C increases chromate toxicity via a death program requiring mismatch repair but not p53. Carcinogenesis 28:1613-20
Reynolds, Mindy; Stoddard, Lauren; Bespalov, Ivan et al. (2007) Ascorbate acts as a highly potent inducer of chromate mutagenesis and clastogenesis: linkage to DNA breaks in G2 phase by mismatch repair. Nucleic Acids Res 35:465-76
Messer, Joseph; Reynolds, Mindy; Stoddard, Lauren et al. (2006) Causes of DNA single-strand breaks during reduction of chromate by glutathione in vitro and in cells. Free Radic Biol Med 40:1981-92
Karaczyn, Aldona; Ivanov, Sergey; Reynolds, Mindy et al. (2006) Ascorbate depletion mediates up-regulation of hypoxia-associated proteins by cell density and nickel. J Cell Biochem 97:1025-35
Zhitkovich, Anatoly; Peterson-Roth, Elizabeth; Reynolds, Mindy (2005) Killing of chromium-damaged cells by mismatch repair and its relevance to carcinogenesis. Cell Cycle 4:1050-2
Zhitkovich, Anatoly (2005) Importance of chromium-DNA adducts in mutagenicity and toxicity of chromium(VI). Chem Res Toxicol 18:3-11
Peterson-Roth, Elizabeth; Reynolds, Mindy; Quievryn, George et al. (2005) Mismatch repair proteins are activators of toxic responses to chromium-DNA damage. Mol Cell Biol 25:3596-607