Resveratrol has been shown to have chemopreventive, cardioprotective, and antiaging properties. Here, we report that resveratrol is a potent inhibitor of quinone reductase 2 (QR2) activity in vitro with a dissociation constant of 35 nM and show that it specifically binds to the deep active-site cleft of QR2 using high-resolution structural analysis. All three resveratrol hydroxyl groups form hydrogen bonds with amino acids from QR2, anchoring a flat resveratrol molecule in parallel with the isoalloxazine ring of FAD. The unique active-site pocket in QR2 could potentially bind other natural polyphenols such as flavonoids, as proven by the high affinity exhibited by quercetin toward QR2. K562 cells with QR2 expression suppressed by RNAi showed similar properties as resveratrol-treated cells in their resistance to quinone toxicity. Furthermore, the QR2 knockdown K562 cells exhibit increased antioxidant and detoxification enzyme expression and reduced proliferation rates. These observations could imply that the chemopreventive and cardioprotective properties of resveratrol are possibly the results of QR2 activity inhibition, which in turn, upregulates the expression of cellular antioxidant enzymes and cellular resistance to oxidative stress.Resveratrol (trans-3,4′,5-trihydroxystilbene) is a phyto-polyphenol that occurs in grapes and a variety of medicinal plants. Because of its abundance in grapes, it is present in significant amount in grape products such as grape juice and wines, particularly red wine (1). The revealing of resveratrol as a cancer chemopreventive agent in 1997 (2) sparked extensive research on its chemopreventive properties (3). Resveratrol has been tested on a variety of cancers in animal model studies. As in the case of the 1997 study, Jang et al. (2) demonstrated in a mouse model that resveratrol is effective in prevention of DMBA-(dimethylbenzanthracene) and TPA-(tetradecanoylphorbol-13-acetate) induced skin cancer. Application of 1, 5, 10, or 25 µM of resveratrol with TPA twice a week for 18 weeks reduced the number of skin tumors per mouse by 68, 81, 76, or 98%, respectively, and the percentage of mice with tumors was lowered by 50, 63. 63, or 88%. In mouse models of colon cancer and small intestinal cancer, resveratrol prevents cancer formation with 100 and 70% efficacy, respectively (4, 5). † This work was supported in part by National Institute of Health Grant R21 CA104424. ‡ The atomic coordinates and structure factors (PDB code 1SG0) NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author ManuscriptResveratrol has been suggested to block the multistep process of carcinogenesis, namely, tumor initiation, promotion, and progression (3). Despite extensive investigation, no clear molecular basis for the actions of resveratrol has emerged. A variety of hypotheses have been proposed to explain its functions: antioxidant effects, proapoptotic effects, cell-cycle regulation, inhibition of protein kinases, regulation of NFκB and Iκ3, and modulation of estrogen effects (3, 6). ...

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Background The fluorochrome‐labeled inhibitors of caspases (FLICA) were recently used as markers of activation of these enzymes in live cells during apoptosis (Bedner et al.: Exp Cell Res 259:308–313, 2000). The aims of this study were to (a) explore if FLICA can be used to study intracellular localization of caspases; (b) combine the detection of caspase activation with analysis of the changes with cell morphology detected by microscopy and laser scanning cytometry (LSC); and (c) adapt the assay to fixed cells that would enable correlation, by multiparameter analysis, of caspase activation with the cell attributes that require cell permeabilization in order to be measured. Methods Apoptosis of human MCF‐7, U‐937, or HL‐60 cells was induced by camptothecin (CPT) or tumor necrosis factor‐α (TNF‐α) combined with cycloheximide (CHX). Binding of FLICA to apoptotic versus nonapoptotic cells was studied in live cells as well as following their fixation and counterstaining of DNA. Intensity of cell labeling with FLICA and DNA‐specific fluorochromes was measured by LSC. Results Exposure of live cells to FLICA led to selective labeling of cells that had morphological changes characteristic of apoptosis. The FLICA labeling withstood cell fixation and permeabilization, which made it possible to stain DNA and measure its content for identification of the cell cycle position of labeled cells. When fixed cells were treated with FLICA, both apoptotic and nonapoptotic cells became strongly labeled and the labeling pattern was consistent with the localization of caspases as reported in the literature. A translocation of the FLICA binding targets from mitochondria to cytosol was seen in the MCF‐7 cells treated with CPT. FLICA binding was largely (>90%) prevented by the substrates of the caspases or by the unlabeled caspase inhibitors having the same peptide moiety as the respective FLICA. Conclusions The detection of caspase activation combined with cell permeabilization requires exposure of live cells to FLICA followed by their fixation. Cell reactivity with the respective FLICA, under these conditions, identifies the activated caspases and makes it possible to correlate their activation with the cell cycle position and other cell attributes that can be measured only after cell fixation/permeabilization. FLICA can also be used to study intracellular localization of caspases, including their translocation. Cytometry 44:73–82, 2001. © 2001 Wiley‐Liss, Inc.

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Coronary heart disease (CHD) is a major and preventable cause of morbidity and death in the United States. Recently, significant research efforts have been directed at an epidemiological phenomenon known as the "French paradox." This observation refers to the coexistence of high risk factors with unanticipated low incidence of CHD, and is postulated to be associated with low-to-moderate consumption of red wine. In vivo studies have shown that red wine intake is more CHD-preventative in comparison to other alcoholic drinks; enhanced cardioprotection may be attributed to grape-derived polyphenols, e.g., resveratrol, in red wine. This review summarizes results of in vitro and animal studies showing that resveratrol exerts multifaceted cardioprotective activities, as well as evidence demonstrating the presence of proteins specifically targeted by resveratrol, as exemplified by N -ribosyldihydronicotinamide:quinone oxidoreductase, NQO2. A mechanism encompassing nongenomic and genomic effects and a research roadmap is proposed as a framework for uncovering further insights on cardioprotection by resveratrol.

Programmed cell death ligand 1 (PD-L1) expressed in cancer cells interacting with its receptor programmed cell death 1 (PD-1) expressed in immune cells represents a regulatory axis linked to the suppression and evasion of host immune functions. The blockade of PD-1/PD-L1 interaction using monoclonal antibodies has emerged as an effective therapy for several solid tumors; however, durable response has been observed in a subset of patients with PD-L1-positive tumors. Thus, the understanding of the mechanisms responsible for the expression of PD-L1 in tumor cells may help to improve the response to PD-L1 blockade therapies. In this study, we investigated whether resveratrol, a grape-derived stilbenoid with immunoregulatory activity, modulates the expression of PD-L1 in breast and colorectal cancer cells. The surface expression of PD-L1 was determined by flow cytometry in cancer cells treated with resveratrol and/or piceatannol. Each stilbenoid alone induced PD-L1 and when used in combination, elicited a synergistic upregulation of PD-L1 in some cell lines. The induction of PD-L1 by the combined use of stilbenoids was most pronounced in the Cal51 triple-negative breast cancer (TNBC) and SW620 colon cancer cells. The observed induction of PD-L1 was transcriptionally mediated by nuclear factor (NF)-κB, as shown by NF-κB reporter assays, the nuclear accumulation of the p65 subunit of NF-κB, inhibition by the IKK inhibitor, BMS-345541, and histone the modification inhibitors, resminostat, entinostat or anacardic acid. Combined treatment with resveratrol and piceatannol also decreased tumor cell survival as indicated by the upregulation of the DNA damaging marker, γH2AX, the cleavage of caspase 3, the downregulation of the survival markers, p38-MAPK/c-Myc, and G1-to-S cell cycle arrest.

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