US EPA

198766 

Journal Article 

Review 

Promotion of hepatocarcinogenesis in humans and animal models 

Köhle, C; Schwarz, M; Bock, KW 

2008 

Yes 

Archives of Toxicology
ISSN: 0340-5761
EISSN: 1432-0738 

82 

9 

623-631 

English 

18204979 

10.1007/s00204-007-0273-7 

WOS:000258757800007 

Risk assessment based on rodent carcinogenicity data depends on the assumption of similarity between rodents and humans. While this assumption is conceivable in the case of genotoxic initiating carcinogens, considerable species differences have been observed with nongenotoxic tumor promoters. This heterogeneous group of agents increases the probability of cancer by stimulating selection and clonal expansion of cells transformed during tumor initiation. Since tumor promoters differentially affect normal tissue and preneoplastic cell clones, their action cannot be discussed without knowledge of persistent genomic and epigenetic alterations occurring during initiation and formation of preneoplastic cells. Chemical carcinogenesis, and in particular, tumor promotion, is known to be tissue specific. We focus on hepatocarcinogenesis in humans and in animal models and emphasize two different modes of action: (1) chronic cytotoxicity leading to promotion of liver carcinogenesis in both humans and animal models; (2) sustained activation of orphan receptors such as CAR, PPARalpha and Ah receptor leading to promotion of rodent but probably not human hepatocarcinogenesis. Further studies on the different modes of action may help to avoid overestimation of the risk of liver tumor promotion. 

Hepatocarcinogenesis; Tumor promoters; Ethanol; Phenobarbital; TCDD