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Published on: December 21, 2011
Frenolicin B Targets Peroxiredoxin 1 and Glutaredoxin 3 to Trigger ROS/4E-BP1-Mediated Antitumor Effects
Qing Ye1, Yinan Zhang2, Yanan Cao1
1Department of Pharmacology and Nutritional Sciences, College of Medicine, University of Kentucky, Lexington, KY 40536, USA; Markey Cancer Center, University of Kentucky, Lexington, KY 40536, USA.
Abstract:
Peroxiredoxin 1 (Prx1) and glutaredoxin 3 (Grx3) are two major antioxidant proteins that play a critical role in maintaining redox homeostasis for tumor progression. Here, we identify the prototypical pyranonaphthoquinone natural product frenolicin B (FB) as a selective inhibitor of Prx1 and Grx3 through covalent modification of active-site cysteines. FB-targeted inhibition of Prx1 and Grx3 results in a decrease in cellular glutathione levels, an increase of reactive oxygen species (ROS), and concomitant inhibition of cancer cell growth, largely by activating the peroxisome-bound tuberous sclerosis complex to inhibit mTORC1/4E-BP1 signaling axis. FB structure-activity relationship studies reveal a positive correlation between inhibition of 4E-BP1 phosphorylation, ROS-mediated cancer cell cytotoxicity, and suppression of tumor growth in vivo. These findings establish FB as the most potent Prx1/Grx3 inhibitor reported to date and also notably highlight 4E-BP1 phosphorylation status as a potential predictive marker in response to ROS-based therapies in cancer.
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