In:
Cancer Research, American Association for Cancer Research (AACR), Vol. 66, No. 4 ( 2006-02-15), p. 2488-2494
Abstract:
Synthetic triterpenoid analogues of oleanolic acid are potent inducers of the phase 2 response as well as inhibitors of inflammation. We show that the triterpenoid, 1-[2-cyano-3-,12-dioxooleana-1,9(11)-dien-28-oyl]imidazole (CDDO-Im), is a highly potent chemopreventive agent that inhibits aflatoxin-induced tumorigenesis in rat liver. The chemopreventive potency of CDDO-Im was evaluated by measuring inhibition of formation of putative preneoplastic lesions (glutathione S-transferase P positive foci) in the liver of rats exposed to aflatoxin B1. CDDO-Im produces an 85% reduction in the hepatic focal burden of preneoplastic lesions at 1 μmol/kg body weight and a & gt;99% reduction at 100 μmol/kg body weight. CDDO-Im treatment reduces levels of aflatoxin-DNA adducts by ∼40% to 90% over the range of 1 to 100 μmol/kg body weight. Additionally, changes in mRNA levels of genes involved in aflatoxin metabolism were measured in rat liver following a single dose of CDDO-Im. GSTA2, GSTA5, AFAR, and EPHX1 transcripts are elevated 6 hours following a 1 μmol/kg body weight dose of CDDO-Im. Microarray analysis using wild-type and Nrf2 knockout mice confirms that many phase 2 and antioxidant genes are induced in an Nrf2-dependent manner in mouse liver following treatment with CDDO-Im. Thus, low-micromole doses of CDDO-Im induce cytoprotective genes, inhibit DNA adduct formation, and dramatically block hepatic tumorigenesis. As a point of reference, oltipraz, an established modulator of aflatoxin metabolism in humans, is 100-fold weaker than CDDO-Im in this rat antitumorigenesis model. The unparalleled potency of CDDO-Im in vivo highlights the chemopreventive promise of targeting Nrf2 pathways with triterpenoids. (Cancer Res 2006; 66(4): 2488-94)
Type of Medium:
Online Resource
ISSN:
0008-5472
,
1538-7445
DOI:
10.1158/0008-5472.CAN-05-3823
Language:
English
Publisher:
American Association for Cancer Research (AACR)
Publication Date:
2006
detail.hit.zdb_id:
2036785-5
detail.hit.zdb_id:
1432-1
detail.hit.zdb_id:
410466-3
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