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On the mechanism of Cr (VI)-induced carcinogenesis: dose dependence of uptake and cellular responses.

Authors
Liu-K; Husler-J; Ye-J; Leonard-SS; Cutler-D; Chen-F; Wang-S; Zhang-Z; Ding-M; Wang-L; Shi-X
Source
Mol Cell Biochem 2001 Jun; 222(1-2):221-229
NIOSHTIC No.
20021794
Abstract
Cr (VI) compounds are widely used industrial chemicals and are recognized human carcinogens. The mechanisms of carcinogenesis associated with these compounds remain to be investigated. The present study focused on dose-dependence of Cr (VI)-induced uptake and cellular responses. The results show that Cr (VI) is able to enter the cells (human lung epithelial cell line A549) at low concentration (< 10 microM) and that the Cr (VI) uptake appears to be a combination of saturable transport and passive diffusion. Electron spin resonance (ESR) trapping measurements showed that upon stimulation with Cr (VI), A549 cells were able to generate reactive oxygen species (ROS). The amount of ROS generated depended on the Cr (VI) concentration. ROS generation involved NADPH-dependent flavoenzymes. Cr (VI) affected the following cellular parameters in a dose-dependent manner, (a) activation of nuclear transcription factors NF-kappaB, and p53, (b) DNA damage, (c) induction of cell apoptosis, and (d) inhibition of cell proliferation. The activation of transcription factors was assessed by electrophoretic mobility shift assay and western blot analysis, DNA damage by single cell gel electrophoresis assay, cell apoptosis by DNA fragmentation assay, and cell proliferation by a non-radioactive ELISA kit. At the concentration range used in the present study, no thresholds were found in all of these cell responses to Cr (VI). The results may guide further research to better understand and evaluate the risk of Cr (VI)-induced carcinogenesis at low levels of exposure.
Keywords
Cellular-reactions; Carcinogenesis; Tumors; Laboratory-animals; Animal-studies; Cancer; Carcinogens; Carcinogenicity; DNA-damage; Risk-factors; Risk-analysis; Exposure-levels; Dose-response; Dosimetry; Antioxidants; Antioxidation
Contact
X. Shi, Pathology and Physiology Research Branch, National Institute for Occupational Safety and Health, 1095 Willowdale Road, Morgantown, WV 26505, USA
CODEN
MCBIB8
CAS No.
18540-29-9
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
NM; WV
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