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 μM caused a growth arrest at G2/M phase. An increase in Cr (VI) concentration enhanced the growth arrest. At a concentration of 25 μM, Cr (VI)-induced apoptosis became apparent. Superoxide dismutase (SOD) or sodium formate did not alter the Cr (VI)-induced cell growth arrest. While the 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.
|Number of pages||7|
|Journal||Molecular and Cellular Biochemistry|
|State||Published - 2001|
Bibliographical noteFunding Information:
Research funded under Interagency Agreement Number 98-18-00m2 between the Occupational Safety and Health Administration and the National Institute for Occupational Safety and Health. The views expressed in the paper are those of the authors and do not necessarily reflect the official positions of OSHA. The authors would like to thank Dr. Murali Rao for his critical review of the manuscript.
- Cell cycle
- Reactive oxygen species
ASJC Scopus subject areas
- Molecular Biology
- Clinical Biochemistry
- Cell Biology