Identification of carbonyl reductase 1 as a resveratrol-binding protein by affinity chromatography using 4'-amino-3,5-dihydroxy-trans-stilbene

Impact of hormesis to deepen our understanding of the mechanisms underlying the bioactivities of polyphenols

Cells, organs, and the whole body are continuously exposed to various types of stressors, including oxidative stress, protein denaturation, hypoxia, energy starvation, and pathogen insults. Hormesis is an adaptive phenomenon in which a stressor induces cellular stress responses at low or moderate doses, while catastrophic damage is manifested at high doses. Polyphenols, as xenobiotic phytochemicals, exhibit stress responses in animal cells, as demonstrated in cellular and rodent models. In this review article, the author highlighted several molecular mechanisms underlying different types of stress adaptation and hormetic phenomena induced by bioactive polyphenols to substantially understand how and why those phytochemicals function in biological systems.

Development of transgenic mice overexpressing mouse carbonyl reductase 1

BACKGROUND

Carbonyl reductase 1 (CBR1) is a nicotinamide adenine dinucleotide phosphate (NADPH)-dependent reductase with broad substrate specificity. CBR1 catalyzes the reduction of numerous carbonyl compounds, including quinones, prostaglandins, menadione, and multiple xenobiotics, while also participating in various cellular processes, such as carcinogenesis, apoptosis, signal transduction, and drug resistance. In this study, we aimed to generate transgenic mice overexpressing mouse Cbr1 (mCbr1), characterize the mCbr1 expression in different organs, and identify changes in protein expression patterns.

METHODS AND RESULTS

To facilitate a deeper understanding of the functions of CBR1, we generated transgenic mice overexpressing CBR1 throughout the body. These transgenic mice overexpress 3xFLAG-tagged mCbr1 (3xFLAG-mCbr1) under the CAG promoter. Two lines of transgenic mice were generated, one with 3xFLAG-mCbr1 expression in multiple tissues, and the other, with specific expression of 3xFLAG-mCbr1 in the heart. Pathway and network analysis using transgenic mouse hearts identified 73 proteins with levels of expression correlating with mCbr1 overexpression. The expression of voltage-gated anion channels, which may be directly related to calcium ion-related myocardial contraction, was also upregulated.

CONCLUSION

mCbr1 transgenic mice may be useful for further in vivo analyses of the molecular mechanisms regulated by Cbr1; such analyses will provide a better understanding of its effects on carcinogenesis and cardiotoxicity of certain cancer drugs.

Resveratrol loaded polymeric micelles for theranostic targeting of breast cancer cells

Treatment of breast cancer underwent extensive progress in recent years with molecularly targeted therapies. However, non-specific pharmaceutical approaches (chemotherapy) persist, inducing severe side-effects. Phytochemicals provide a promising alternative for breast cancer prevention and treatment. Specifically, resveratrol (res) is a plant-derived polyphenolic phytoalexin with potent biological activity but displays poor water solubility, limiting its clinical use. Here we have developed a strategy for delivering res using a newly synthesized nano-carrier with the potential for both diagnosis and treatment.

Methods: Res-loaded nanoparticles were synthesized by the emulsion method using Pluronic F127 block copolymer and Vitamin E-TPGS. Nanoparticle characterization was performed by SEM and tunable resistive pulse sensing. Encapsulation Efficiency (EE%) and Drug Loading (DL%) content were determined by analysis of the supernatant during synthesis. Nanoparticle uptake kinetics in breast cancer cell lines MCF-7 and MDA-MB-231 as well as in MCF-10A breast epithelial cells were evaluated by flow cytometry and the effects of res on cell viability via MTT assay.

Results: Res-loaded nanoparticles with spherical shape and a dominant size of 179±22 nm were produced. Res was loaded with high EE of 73±0.9% and DL content of 6.2±0.1%. Flow cytometry revealed higher uptake efficiency in breast cancer cells compared to the control. An MTT assay showed that res-loaded nanoparticles reduced the viability of breast cancer cells with no effect on the control cells.

Conclusions: These results demonstrate that the newly synthesized nanoparticle is a good model for the encapsulation of hydrophobic drugs. Additionally, the nanoparticle delivers a natural compound and is highly effective and selective against breast cancer cells rendering this type of nanoparticle an excellent candidate for diagnosis and therapy of difficult to treat mammary malignancies.

(E)-1-(Furan-2-yl)-(substituted phenyl)prop-2-en-1-one Derivatives as Tyrosinase Inhibitors and Melanogenesis Inhibition: An In Vitro and In Silico Study

A series of (E)-1-(furan-2-yl)prop-2-en-1-one derivatives (compounds 1–8) were synthesized and evaluated for their mushroom tyrosinase inhibitory activity. Among these series, compound 8 (2,4-dihydroxy group bearing benzylidene) showed potent tyrosinase inhibitory activity, with respective IC₅₀ values of 0.0433 µM and 0.28 µM for the monophenolase and diphenolase as substrates in comparison to kojic acid as standard compound 19.97 µM and 33.47 µM. Moreover, the enzyme kinetics of compound 8 were determined to be of the mixed inhibition type and inhibition constant (K_i) values of 0.012 µM and 0.165 µM using the Lineweaver-Burk plot. Molecular docking results indicated that compound 8 can bind to the catalytic and allosteric sites 1 and 2 of tyrosinase to inhibit enzyme activity. The computational molecular dynamics analysis further revealed that compound 8 interacted with two residues in the tyrosinase active site pocket, such as ASN260 and MET280. In addition, compound 8 attenuated melanin synthesis and cellular tyrosinase activity, simulated by α-melanocyte-stimulating hormone and 1-methyl-3-isobutylxanthine. Compound 8 also decreased tyrosinase expressions in B16F10 cells. Based on in vitro and computational studies, we propose that compound 8 might be a worthy candidate for the development of an antipigmentation agent.

Control of DNA structure and function by phytochemicals/DNA interaction: Resveratrol/piceatannol induces Cu2+-independent, cleavage of supercoiled plasmid DNA

Topoisomerases are enzymes that catalyze DNA unwinding and scissions to resolve topological entanglements possibly arising during DNA replication/transcription. Chemicals which disrupt or inhibit topoisomerase-mediated DNA unwinding can induce breaks that subsequently lead to programmed cell death. Herein we perform experiments guided by the following considerations. First, topoisomerase 1 initiates DNA cleavage utilizing the hydroxyl group of tyrosine 723 on its catalytic site as a nucleophile to attack the electrophilic phosphate on the DNA sugar-phosphate backbone. Secondly, the grape polyphenol resveratrol displays both topoisomerase inhibitory and Cu²⁺-dependent DNA-cutting activities, which contribute to its DNA replication/transcription inhibitory/anti-tumorigenic effects. Lastly, resveratrol contains a tyrosine-like phenolic ring; thus, upon binding to DNA whether resveratrol could act as a tyrosine mimetic to unwind and cut DNA via its hydroxyl groups warrants investigation. Polyphenol-DNA interactions (PDIs) were investigated using UV-visible spectral analysis; additionally, PDI mediated DNA changes were further analyzed by agarose gel electrophoresis using 3 supercoiled plasmid DNAs (pBR322, pSJ3, pHOT-1) as substrates. Resveratrol mediates time- and temperature-dependent, Cu²⁺-independent, non-enzymatic cleavage of supercoiled plasmid DNA into open, circular DNA products. Varying degree of unwinding of supercoiled DNA nucleolytic activity was also observed with other polyphenols including, piceatannol, quercetin, myricetin and EGCG. Interestingly, we found that piceatannol mediated Cu²⁺-independent DNA-cleavage activity was abolished by EDTA. The PDI-mediated nucleolytic cleavage of supercoiled DNA reported herein shows that polyphenolic phytochemicals display genome-active, nuclear effects by directly targeting the DNA topology which in turn could impact macromolecular processes associated with faithful replication and transmission of genetic information.

A Review of Resveratrol as a Potent Chemoprotective and Synergistic Agent in Cancer Chemotherapy

Background: Cancer has become a major disease endangering human health around the world. Conventional chemotherapy suffers from many side effects including pain, cardiotoxicity, hepatotoxicity, and renal toxicity. This review aims to describe a natural product of resveratrol as a chemoprotective and synergistic agent in the modulation of cancer chemotherapy.

Methods: The publications were identified by comprehensive searching of SciFinder, PubMed, Web of Science, and our own reference library. Search terms included combinations of “resveratrol,” “cancer,” “natural products,” “chemotherapy,” and “side effects.” Selection of material focused on resveratrol reducing the side effects on cancer chemotherapy.

Results: Thirty one references were referred in this review to outline resveratrol as a potent chemoprotective and synergistic agent in cancer chemotherapy, including 22 papers for describing the chemoprotective effects, and 9 papers for illustrating the synergistic effects.

Conclusion: This study provides a systematic summary of resveratrol serving as a potent chemoprotective and synergistic agent to reduce the associated-side effects and enhance the therapeutic outcomes in cancer chemotherapy. Further studies in terms of resveratrol on a large amount of preclinical tests and clinical trials are highly demanded.

Upregulation of PD‑L1 expression by resveratrol and piceatannol in breast and colorectal cancer cells occurs via HDAC3/p300‑mediated NF‑κB signaling

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.

Functional/activity network (FAN) analysis of gene-phenotype connectivity liaised by grape polyphenol resveratrol

Resveratrol is a polyphenol that has witnessed an unprecedented yearly growth in PubMed citations since the late 1990s. Based on the diversity of cellular processes and diseases resveratrol reportedly affects and benefits, it is likely that the interest in resveratrol will continue, although uncertainty regarding its mechanism in different biological systems remains.

We hypothesize that insights on disease-modulatory activities of resveratrol might be gleaned by systematically dissecting the publicly available published data on chemicals and drugs. In this study, we tested our hypothesis by querying DTome (Drug-Target Interactome), a web-based tool containing data compiled from open-source databases including DrugBank, PharmGSK, and Protein Interaction Network Analysis (PINA). Four direct protein targets (DPT) and 219 DPT-associated genes were identified for resveratrol. The DPT-associated genes were scrutinized by WebGestalt (WEB-based Gene SeT Analysis Toolkit). This enrichment analysis resulted in 10 identified KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways. Refined analysis of KEGG pathways showed that 2 — one linked to p53 and a second to prostate cancer — have functional connectivity to resveratrol and its four direct protein targets. These results suggest that a functional activity network (FAN) approach may be considered as a new paradigm for guiding future studies of resveratrol. FAN analysis resembles a BioGPS, with capability for mapping a Web-based scientific track that can productively and cost effectively connect resveratrol to its primary and secondary target proteins and to its biological functions.

Metabolic carbonyl reduction of anthracyclines - role in cardiotoxicity and cancer resistance. Reducing enzymes as putative targets for novel cardioprotective and chemosensitizing agents

Anthracycline antibiotics (ANT), such as doxorubicin or daunorubicin, are a class of anticancer drugs that are widely used in oncology. Although highly effective in cancer therapy, their usefulness is greatly limited by their cardiotoxicity. Possible mechanisms of ANT cardiotoxicity include their conversion to secondary alcohol metabolites (i.e. doxorubicinol, daunorubicinol) catalyzed by carbonyl reductases (CBR) and aldo-keto reductases (AKR). These metabolites are suspected to be more cardiotoxic than their parent compounds. Moreover, overexpression of ANT-reducing enzymes (CBR and AKR) are found in many ANT-resistant cancers. The secondary metabolites show decreased cytotoxic properties and are more susceptible to ABC-mediated efflux than their parent compounds; thus, metabolite formation is considered one of the mechanisms of cancer resistance. Inhibitors of CBR and AKR were found to reduce the cardiotoxicity of ANT and the resistance of cancer cells, and therefore are being investigated as prospective cardioprotective and chemosensitizing drug candidates. In this review, the significance of a two-electron reduction of ANT, including daunorubicin, epirubicin, idarubicin, valrubicin, amrubicin, aclarubicin, and especially doxorubicin, is described with respect to toxicity and efficacy of therapy. Additionally, CBR and AKR inhibitors, including monoHER, curcumin, (−)-epigallocatechin gallate, resveratrol, berberine or pixantrone, and their modulating effect on the activity of ANT is characterized and discussed as potential mechanism of action for novel therapeutics in cancer treatment.

Resveratrol for breast cancer prevention and therapy: Preclinical evidence and molecular mechanisms

Globally, breast cancer is the most frequently diagnosed cancer among women. The major unresolved problems with metastatic breast cancer is recurrence after receiving objective response to chemotherapy, drug-induced side effects of first line chemotherapy and delayed response to second line of treatment. Unfortunately, very few options are available as third line treatment. It is clear that under such circumstances there is an urgent need for new and effective drugs. Phytochemicals are among the most promising chemopreventive treatment options for the management of cancer. Resveratrol (3,5,4'-trihydroxy-trans-stilbene), a non-flavonoid polyphenol present in several dietary sources, including grapes, berries, soy beans, pomegranate and peanuts, has been shown to possess a wide range of health benefits through its effect on a plethora of molecular targets.The present review encompasses the role of resveratrol and its natural/synthetic analogue in the light of their efficacy against tumor cell proliferation, metastasis, epigenetic alterations and for induction of apoptosis as well as sensitization toward chemotherapeutic drugs in various in vitro and in vivo models of breast cancer. The roles of resveratrol as a phytoestrogen, an aromatase inhibitor and in stem cell therapy as well as adjuvent treatment are also discussed. This review explores the full potential of resveratrol in breast cancer prevention and treatment with current limitations, challenges and future directions of research.

Resveratrol: challenges in analyzing its biological effects

Testing the biological activities of a dietary compound like resveratrol presents various challenges, which are highlighted in this commentary, with some suggested direction for future research, focusing on five challenges: (1) many different cellular effects are observed for resveratrol, but it is not known whether they arise from one point of action (or a few) or whether resveratrol is non-specific in its action; (2) the health-promotion effect of dietary resveratrol is likely a combinatory effect of various bioactive components in the mixture (diet); (3) the known cell biological response to resveratrol is presently based on exposure to short-term high levels, and better in vitro analyses have to be developed; (4) the actual level of resveratrol and resveratrol metabolites present in vitro and in vivo during experiments may be over- and underestimated, respectively, because resveratrol is not very soluble in water; and (5) only a few small clinical studies have been published to date, focusing on the therapeutic effects of resveratrol. Further, clinical trials addressing the disease-preventive effects are especially challenging.

Direct molecular targets of resveratrol: identifying key interactions to unlock complex mechanisms

To truly understand the mechanisms through which resveratrol exerts its biological effects, the key direct interactions between resveratrol and its target biomolecules must be identified. With an increasing number of biochemical tools to measure and quantify direct physical interactions between biomolecules, there have been around 20 proteins identified as having a specific affinity to resveratrol to date. Resveratrol has been described as a promiscuous molecule, and one would expect it to bind with numerous proteins, which would help explain why resveratrol appears to have so many health benefits and has been shown to act upon various different pathways related to a diverse range of conditions. The aim of this review is to present the direct protein targets of resveratrol that are currently known and highlight the consequences of direct binding and the methods used to identify the nature of these interactions.