Abstract |
DNA double-strand breaks (DSBs) induced by exposure to genotoxic agents are known to cause genome instability and cancer development. To evaluate the applicability of γ-H2AX, a sensitive marker of DSBs, in the early detection of genotoxicity and carcinogenicity of chemicals using animal models, we examined γ-H2AX expression in urinary bladders of rats. Six-week-old male F344 rats were orally treated for 4 weeks with a total of 12 chemicals divided into 4 categories based on genotoxicity and carcinogenicity in the urinary bladder. Animals were sacrificed at the end of administration or after 2 weeks of recovery, and immunohistochemistry for γ-H2AX was performed. At week 4, γ-H2AX expression in bladder epithelial cells was significantly increased by all 4 genotoxic bladder carcinogens as compared with the controls, whereas the 3 chemicals that were genotoxic but not carcinogenic in the bladders did not cause upregulation of γ-H2AX. After the recovery period, γ-H2AX expression was markedly reduced in all groups but remained significantly elevated in rats treated with 3 of the 4 genotoxic bladder carcinogens. Although slight increases in γ-H2AX expression were induced by a weak bladder carcinogen with equivocal genotoxicity ( phenethyl isothiocyanate) and 2 nongenotoxic bladder carcinogens ( melamine and uracil) at week 4, these differences were not significant and were thought to be associated with activated proliferation by urothelial hyperplasia, as demonstrated by increased Ki67-positive cells. These results suggested that γ-H2AX may be a potential biomarker for the early detection of genotoxic bladder carcinogens.
|
Authors | Takeshi Toyoda, Young-Man Cho, Jun-Ichi Akagi, Yasuko Mizuta, Tadashi Hirata, Akiyoshi Nishikawa, Kumiko Ogawa |
Journal | Toxicological sciences : an official journal of the Society of Toxicology
(Toxicol Sci)
Vol. 148
Issue 2
Pg. 400-8
(Dec 2015)
ISSN: 1096-0929 [Electronic] United States |
PMID | 26338220
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
|
Copyright | © The Author 2015. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For Permissions, please e-mail: [email protected]. |
Chemical References |
- Biomarkers, Tumor
- Histones
- Ki-67 Antigen
- Phosphoproteins
- gamma-H2AX protein, rat
|
Topics |
- Animals
- Biomarkers, Tumor
(metabolism)
- Cell Differentiation
(drug effects)
- Cell Proliferation
(drug effects)
- Early Detection of Cancer
(methods)
- Histones
(metabolism)
- Hyperplasia
- Immunohistochemistry
- Ki-67 Antigen
(metabolism)
- Male
- Mutagenicity Tests
(methods)
- Phosphoproteins
(metabolism)
- Predictive Value of Tests
- Rats, Inbred F344
- Time Factors
- Up-Regulation
- Urinary Bladder
(drug effects, metabolism, pathology)
- Urinary Bladder Neoplasms
(chemically induced, metabolism, pathology)
|