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Cr(VI) induces cell growth arrest through hydrogen peroxide-mediated reactions.

Authors
Zhang-Z; Leonard-SS; Wang-S; Vallyathan-V; Castranova-V; Shi-X
Source
Mol Cell Biochem 2001 Jun; 222(1-2):77-83
NIOSHTIC No.
20021940
Abstract
Cr (VI) compounds are widely used in industries and are recognized human carcinogens. The mechanism of carcinogenesis associated with these compounds is not well understood. The present study focused on Cr (VI)-induced cell growth arrest in human lung epithelial A549 cells, using flow cytometric analysis of DNA content. Treatment of the cells with Cr (VI) at 1 microM caused a growth arrest at G2/M phase. An increase in Cr (VI) concentration enhanced the growth arrest. At a concentration of 25 microM, Cr (VI)-induced apoptosis became apparent. Superoxide dismutase (SOD) or sodium formate did not alter the Cr (VI)-induced cell growth arrest. While catalase inhibited growth, indicating H2O2 is an important mediator in Cr (VI)-induced G2/M phase arrest. Electron spin resonance (ESR) spin trapping measurements showed that incubation of cells with Cr (VI) generated hydroxyl radical (OH). Catalase inhibited the OH radical generation, indicating that H2O2 was generated from cells stimulated by Cr (VI), and that H2O2 functioned as a precursor for OH radical generation. The formation of H2O2 from Cr (VI)-stimulated cells was also measured by the change in fluorescence of scopoletin in the presence of horseradish peroxidase. The mechanism of reactive oxygen species generation involved the reduction of molecular oxygen as shown by oxygen consumption assay. These results support the following conclusions: (a) Reactive oxygen species are generated in Cr (VI)-stimulated A549 cells through reduction of molecular oxygen, (b) Among the reactive oxygen species generated, H2O2 played a major role in causing G2/M phase arrest in human lung epithelial cells.
Keywords
Cell-growth; Chromium-compounds; Carcinogens; Lung-cells; Humans; Cell-cultures; Cell-biology; Cell-function; Cell-division; Cellular-function
CODEN
MCBIB8
CAS No.
7440-47-3
Publication Date
20010601
Document Type
Journal Article
Email Address
xshi@cdc.gov
Fiscal Year
2001
NTIS Accession No.
NTIS Price
Issue of Publication
1-2
ISSN
0300-8177
NIOSH Division
HELD
Source Name
Molecular and Cellular Biochemistry
State
WV
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