Carcinogenesis Advance Access originally published online on June 23, 2005
Carcinogenesis 2005 26(11):1835-1845; doi:10.1093/carcin/bgi160
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Carcinogenesis vol.26 no.11 © Oxford University Press 2005; all rights reserved.
REVIEW |
Hormesis and doseresponse-mediated mechanisms in carcinogenesis: evidence for a threshold in carcinogenicity of non-genotoxic carcinogens
Department of Pathology, Osaka City University Medical School, 1-4-3 Asahi-machi Abeno-ku, Osaka 545-8585, Japan
* To whom correspondence should be addressed. Email: fukuchan{at}med.osaka-cu.ac.jp
Recently the idea of hormesis, a biphasic doseresponse relationship in which a chemical exerts opposite effects dependent on the dose, has attracted interest in the field of carcinogenesis. With non-genotoxic agents there is considerable experimental evidence in support of hormesis and the present review highlights current knowledge of doseresponse effects. In particular, several in vivo studies have provided support for the idea that non-genotoxic carcinogens may inhibit hepatocarcinogenesis at low doses. Here, we survey the examples and discuss possible mechanisms of hormesis using phenobarbital, 1,1-bis(p-chlorophenyl)-2,2,2-trichloroethane (DDT),
-benzene hexachloride (
-BHC) and other non-genotoxins. Furthermore, the effects of low and high doses of non-genotoxic and genotoxic compounds on carcinogenesis are compared, with especial attention to differences in mechanisms of action in animals and possible application of the doseresponse concept to cancer risk assessment in humans. Epigenetic processes differentially can be affected by agents that impinge on oxidative stress, DNA repair, cell proliferation, apoptosis, intracellular communication and cell signaling. Non-genotoxic carcinogens may target nuclear receptors, cause aberrant DNA methylation at the genomic level and induce post-translational modifications at the protein level, thereby impacting on the stability or activity of key regulatory proteins, including oncoproteins and tumor suppressor proteins. Genotoxic agents, in contrast, cause genetic change by directly attacking DNA and inducing mutations, in addition to temporarily modulating the gene activity. Carcinogens can elicit a variety of changes via multiple genetic and epigenetic lesions, contributing to cellular carcinogenesis.
![]()
CiteULike
Connotea
Del.icio.us What's this?
This article has been cited by other articles:
![]() |
W J Waddell Critique of dose response in carcinogenesis Human and Experimental Toxicology, July 1, 2006; 25(7): 413 - 436. [Abstract] [PDF] |
||||
