Carcinogenesis Advance Access first published online on April 13, 2007
This version published online on April 17, 2007
Carcinogenesis, doi:10.1093/carcin/bgm080
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Chemopreventive effects of lupulone, a hop ß-acid, on human colon cancer-derived metastatic SW620 cells and in a rat model of colon carcinogenesis
1 Inserm U682, Laboratoire de Prévention Nutritionnelle du Cancer, Strasbourg, F-67000 France
2 Université Louis Pasteur EA3430, Faculté de Médecine, Strasbourg, F-67000 France
3 IRCAD, Strasbourg, F-67000 France
4 CNRS UMR7081, Laboratoire de Pharmacognosie, Illkirch, F-67400
5 Université Louis Pasteur, Faculté de Pharmacie, Illkirch, F-67400 France
* To whom correspondence should be addressed at: IRCAD, 1, place de l'Hôpital, BP 426, 67091 Strasbourg-Cedex, France. Tel: +33(0)388119023; Fax: +33(0)388119097; E-mail: francis.raul{at}ircad.u-strasbg.fr
The bitter acids of hops (Humulus lupulus L.) mainly consist of humulones or
-acids and lupulones or ß-acids. We aimed to evaluate the antiproliferative mechanisms of lupulones on a human metastatic colon carcinoma-derived cell line (SW620 cells) and to assess their chemopreventive effects in a model of colon carcinogenesis. SW620 cell growth was inhibited by 70% after a 48 h exposure to lupulones (40 µg/ml). Lupulones up-regulated the expression of Fas receptor and Fas ligand as well as TRAIL-R1 (DR4) and R2 (DR5) receptor proteins, suggesting the involvement of Fas and TRAIL receptors-mediated pathways in lupulone-induced apoptosis. Lupulones increased also mitochondrial membrane permeability. Colon carcinogenesis was initiated in Wistar rats by intraperitoneal injections of azoxymethane (AOM), once a week for 2 weeks. One week after the last injection, rats received lupulones (0.001% or 0.005%) in drinking water, AOM-control rats received the excipient. After 7 months of treatment, the colon of rats receiving 0.001% and 0.005% lupulones showed respectively a 30% and a 50% reduction (P<0.05) of the number of preneoplastic lesions (aberrant crypt foci). In addition, we observed a drastic reduction (70-80%) of the total number of tumors in the colon of rats treated with lupulones when compared with the AOM-control group. Lupulones induced apoptosis in SW620 colon-derived metastatic cells by activating both Fas and TRAIL death receptor signalling pathways, and antagonize at a low dose (4 mg/kg/day) colon cancer development. These observations suggest the use of lupulones for colon cancer chemoprevention trials.
The figures have been added in this version.
Received February 12, 2007; revised March 29, 2007; accepted April 2, 2007.