IMR Press / FBL / Volume 12 / Issue 5 / DOI: 10.2741/2199

Frontiers in Bioscience-Landmark (FBL) is published by IMR Press from Volume 26 Issue 5 (2021). Previous articles were published by another publisher on a subscription basis, and they are hosted by IMR Press on imrpress.com as a courtesy and upon agreement with Frontiers in Bioscience.

Open Access Article
Structure-proteasome-inhibitory activity relationships of dietary flavonoids in human cancer cells
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1 The Prevention Program, Barbara Ann Karmanos Cancer Institute, and Department of Pathology, Wayne State University School of Medicine, Detroit, MI 48201, USA
Academic Editor:Q. Ping Dou
Front. Biosci. (Landmark Ed) 2007, 12(5), 1935–1945; https://doi.org/10.2741/2199
Published: 1 January 2007
(This article belongs to the Special Issue Metals and their regulatory roles in ubiquitin-proteasome pathway)
Abstract

Diet high in vegetables and fruits has been associated with reduced cancer risk. However, the involved mechanisms are unknown. Previously, we reported that the dietary flavonoid apigenin could inhibit the proteasome activity and induce apoptosis in tumor cells. To further investigate the structure-proteasome-inhibitory activity relationships, we chose and tested five dietary flavonoids, including luteolin, apigenin, chrysin, naringenin and eriodictyol. We found that the order of inhibitory potencies and apoptosis-inducing potencies of these five compounds in 20S purified proteasome and tumor cells was: (1) luteolin > apigenin > chrysin, and (2) apigenin >> naringenin, and luteolin >> eriodictyol. Therefore, flavonoids with hydroxylized B ring and/or unsaturated C ring are natural potent proteasome inhibitors and tumor cell apoptosis inducers. Furthermore, neither apigenin nor luteolin could inhibit the proteasome and induce apoptosis in non-transformed human natural killer cells. This finding may provide a molecular basis for the clinically observed cancer-preventive effects of fruits and vegetables.

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