Aromatic amines in experimental cancer research: tissue-specific effects, an old problem and new solutions.
Carcinogenic aromatic amines usually produce tumors in specific target tissue, such as 2-acetylaminofluorene (AAF) producing liver tumors in rats, in contrast to some other structurally related arylamines. A hypothesis is presented that explains the mode of action in this rat liver model. Genotoxic and nongenotoxic effects work together and make AAF a complete rat liver carcinogen. The cytotoxic, promoting effects are particularly important. N-Hydroxy-2-aminofluorene and 2-nitrosofluorene, two metabolites of AAF, are able to uncouple the mitochondrial respiratory chain. They entertain a redox cycle that removes electrons from the respiratory chain and impairs ATP production. The dose-dependent opening of the mitochondrial permeability transition pore signals the viability of the cell. If the pore is opened to a certain extent, the cell is eliminated by apoptosis. As a consequence, oval cells proliferate, and as this process is overloaded, the liver transforms into a cirrhosis-like situation and thus provides the conditions under which initiated liver cells develop tumors. Such an interpretation is based on assumptions that have been debated for a long time. Some of these often forgotten developments are reviewed in support of the hypothesis, which allows a more comprehensive view of the complex in vivo situation at a time when in vitro models prevail.
Neumann
H-G
HG
Department of Toxicology, University of Würzburg, Germany. hg-neumann@t-online.de
D000588:Amines / Q000633:toxicity*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002273:Carcinogens / Q000633:toxicity*; D049109:Cell Proliferation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008113:Liver Neoplasms / Q000139:chemically induced / Q000473:pathology; D008928:Mitochondria / Q000187:drug effects / Q000502:physiology; D009374:Neoplasms, Experimental / Q000139:chemically induced* / Q000473:pathology*; D009928:Organ Specificity; D010100:Oxygen / Q000502:physiology; D051381:Rats
D000588:Amines; D002273:Carcinogens; D010100:Oxygen