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

K. Liu, J. HuslerSurname, J. Ye, S. S. Leonard, D. Cutler, F. Chen, S. Wang, Z. Zhang, M. Ding, L. Wang, X. Shi

Research output: Contribution to journalArticlepeer-review

61 Scopus citations

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 μM) 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-κB, 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.

Original languageEnglish
Pages (from-to)221-229
Number of pages9
JournalMolecular and Cellular Biochemistry
Volume222
Issue number1-2
DOIs
StatePublished - 2001

Bibliographical note

Funding 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 are not necessarily the official position of OSHA. We appreciate the suggestions and comments from Dr. Val Schaeffer, Jeff Snyder, Caroline Freeman, William G. Perry, Health Standards Programs, Occupational Safety and Health Administration, Washington, DC, on the present work. We thank Drs. Vince Castranova, Murali Rao, and Val Val-lyathan for critical review of the manuscript.

Keywords

  • Carcinogenesis
  • Cellular responses
  • Cr (VI)
  • Reactive oxygen species
  • Uptake

ASJC Scopus subject areas

  • Molecular Biology
  • Clinical Biochemistry
  • Cell Biology

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