The inhibition effect of 2,3,7,8-tetrachlorinated dibenzo-p-dioxin-induced aryl hydrocarbon receptor activation in human hepatoma cells with the treatment of cadmium chloride.

Abstract

Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), considered as endocrine disruptors, tend to accumulate in fatty tissues. Dioxin-responsive element chemical activated luciferase gene expression assay (DRE-luciferase assay) has been recognized as a semi-quantitative method for screening dioxins for its fast and low-cost as compared with HRGC/HRMS. However, some problems with the bioassay, including specificity, detection variation resulted from different cleanup strategies, and uncertainty of false-negative or false-positive results, remain to be overcome. Cadmium is a prevalent environmental contaminant around the world. This study was aimed to examine the effects of cadmium on the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced activation of aryl hydrocarbon receptor (AhR)-mediated gene expression in human hepatoma cells (Huh7-DRE-Luc cells and Huh7 cells). Ethoxyresorufin-O-deethylase (EROD) and DRE-luciferase assay were employed to determine the enzyme activity of cytochrome P450 1A1 (CYP1A1) and activation of AhR, respectively. The results showed that Cd(2+) levels significantly inhibited the induction of TCDD-induced CYP1A1 and DRE luciferase activation in hepatoma cells. The 50% inhibited concentrations (IC(50)) of CdCl(2) were 0.414 microM (95% confidence interval (C.I.): 0.230-0.602 microM) in Huh7-DRE-Luc cells and 23.2 microM (95% C.I.: 21.7-25.4 microM) in Huh7 cells. Accordingly, prevention of interference with non-dioxin-like compounds in a DRE-luciferase assay is of great importance in an extensive cleanup procedure.

• Authors: How-Ran Chao, Tsui-Chun Tsou, Hung-Ta Chen, Eddy Essen Chang, Feng-Yuan Tsai, Ding-Yan Lin, Fu-An Chen, Ya-Fen Wang
• Journal: Journal of hazardous materials (J Hazard Mater) Vol. 170 Issue 1 Pg. 351-6 (Oct 15 2009) ISSN: 1873-3336 [Electronic] Netherlands
• PMID: 19477068 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Endocrine Disruptors
• Environmental Pollutants
• Polychlorinated Dibenzodioxins
• Receptors, Aryl Hydrocarbon
• Cytochrome P-450 CYP1A1
• Cadmium Chloride

Topics

• Cadmium Chloride (pharmacology)
• Carcinoma, Hepatocellular (pathology)
• Cytochrome P-450 CYP1A1 (analysis, metabolism)
• Drug Evaluation, Preclinical (methods)
• Endocrine Disruptors (pharmacology)
• Environmental Pollutants
• Humans
• Inhibitory Concentration 50
• Polychlorinated Dibenzodioxins (pharmacology)
• Receptors, Aryl Hydrocarbon (antagonists & inhibitors, metabolism)
• Transcriptional Activation (drug effects)
• Tumor Cells, Cultured