Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9018407 | Toxicology and Applied Pharmacology | 2005 | 8 Pages |
Abstract
1,1-Bis(4-chlorophenyl)-2,2,2-trichloroethane (DDT) is an organochlorine pesticide. Its metabolite, 1,1-dichloro-2,2-bis(p-chlorophenyl)-ethene (p,pâ²-DDE) is a persistent environmental contaminant and both compounds accumulate in animals. Because multidrug resistance transporters, such as p-glycoprotein, function as a defense against xenobiotic exposure, we analyzed the ability of DDT and p,pâ²-DDE to act as efflux modulators. Using a competitive intact cell assay based on the efflux of the fluorescent dye rhodamine 123, we found that DDT, but not p,pâ²-DDE, stimulated dye retention. Subsequent studies using verapamil as competitor suggested that DDT is a weak p-glycoprotein inhibitor. Further studies addressed the ability of DDT and p,pâ²-DDE to induce MDR1, the gene encoding p-glycoprotein. In HepG2 cells, we found that both compounds induced MDR1 by twofold to threefold. Similar results were observed in mouse liver after a single dose of p,pâ²-DDE, although some gender-specific induction differences were noted. By contrast, p,pâ²-DDE failed to induce MDR1 in HeLa cells, indicating some cell-specific effects for induction. Further expression studies demonstrated increased levels of the endoplasmic reticulum molecular chaperone, Bip, in response to DDT, but not p,pâ²-DDE. These results suggest that DDT, but not p,pâ²-DDE, induces an endoplasmic reticulum stress response.
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Authors
Arsalan Shabbir, Susan DiStasio, Jingbo Zhao, Christopher P. Cardozo, Mary S. Wolff, Avrom J. Caplan,