TOXI 105 |
| Arsenic in drinking water is associated with skin and other cancers. Arsenic in drinking water does not cause skin cancers in mice, but enhances the skin tumorigenicity of solar UV irradiation. Arsenic compounds do not react with DNA and are not directly mutagenic, but arsenite is a comutagen and causes genomic instability (delayed mutagenesis). Other cocarcinogenic mechanisms might include effects on DNA repair, DNA methylation, aneuploidy, and signaling changes. Arsenic and selenium are mutually antagonistic. Low selenium levels may exacerbate effects of arsenic in some parts of the world. Selenium enhances the biliary excretion of arsenic through formation of a diglutathione compound [(GS)2AsSe]-. Organoselenium compounds blocked arsenite-induced delayed mutagenesis. A synthetic selenium compound p-XSC prevented arsenite's cocarcinogenesis. Selenium may protect via the antioxidant action of selenoproteins, increasing biliary excretion of arsenic or other affects on arsenic metabolism. Our results suggest that arsenic needs a carcinogenic partner. |
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Metal Carcinogenesis: New Concepts
2:00 PM-5:00 PM, Wednesday, 13 September 2006 Moscone Center -- Room 308, Oral
Division of Chemical Toxicology |