Inhibition of melanoma cell proliferation by resveratrol is correlated with upregulation of quinone reductase 2 and p53

New insights into the anti-inflammatory and anti-melanoma mechanisms of action of azelaic acid and other Fusarium solani metabolites via in vitro and in silico studies

Metabolites exploration of the ethyl acetate extract of Fusarium solani culture broth that was isolated from Euphorbia tirucalli root afforded five compounds; 4-hydroxybenzaldehyde (1), 4-hydroxybenzoic acid (2), tyrosol (3), azelaic acid (4), malic acid (5), and fusaric acid (6). Fungal extract as well as its metabolites were evaluated for their anti-inflammatory and anti-hyperpigmentation potential via in vitro cyclooxygenases and tyrosinase inhibition assays, respectively. Azelaic acid (4) exhibited powerful and selective COX-2 inhibition followed by fusaric acid (6) with IC50 values (2.21 ± 0.06 and 4.81 ± 0.14 μM, respectively). As well, azelaic acid (4) had the most impressive tyrosinase inhibitory effect with IC50 value of 8.75 ± 0.18 μM compared to kojic acid (IC50 = 9.27 ± 0.19 μM). Exclusive computational studies of azelaic acid and fusaric acid with COX-2 were in good accord with the in vitro results. Interestingly, this is the first time to investigate and report the potential of compounds 3-6 to inhibit cyclooxygenase enzymes. One of the most invasive forms of skin cancer is melanoma, a molecular docking study using a set of enzymes related to melanoma suggested pirin to be therapeutic target for azelaic acid and fusaric acid as a plausible mechanism for their anti-melanoma activity.

Resveratrol improves postharvest quality of tomato fruists by enhancing the antioxidant defense system and inhibiting ethylene biosynthesis

Resveratrol, the most widely studied phytoalexin, derived from the skin of grapes and other fruits. Evidence from numerous studies have confirmed its extensive bioactivities, such as antioxidation, anti-inflammatory and anticancer, as well as to promote antiaging effects in organisms. However, the effect of resveratrol on prolonging the postharvest storage of tomato fruits is still unknown. Here, our data provide evidence that tomato fruits applied 200 μM resveratrol displayed a significant delay in changes of weight loss, titratable acidity, soluble solids concentration, soluble protein, vitamin C and lycopene content compared to control fruits during storage. In addition, resveratrol treatment could stimulate the antioxidant defense system to inhibit the production of ROS and down-regulate the expression of ethylene biosynthesis genes. Taken together, our results suggest that resveratrol could benefit in delaying senescence and preserving the postharvest quality of tomato fruits.

Natural substances in cancer—do they work?

Owing to anticancer properties of selected natural substances, it is assumed that they have potential to be used in oncological therapy. Here, the recently proven effects of the selected natural polyphenols, resveratrol and curcumin, are described. Secondly, the potential of probiotics and prebiotics in modulation of immunological response and/or enhancing the chemotherapeutic treatments is reported based on the recent clinical trials. Further, the chapter presents current knowledge regarding the targeted supplementation of the patient with probiotic bacteria and known efficacy of probiotics to support immunotherapy. The major clinical trials are listed, aiming to verify whether, and to which extent the manipulation of patient’s microbiome can improve the outcome of chemotherapies. In the end, a potential of natural substances and feed ingredients to pose epigenetic changes is highlighted. The chapter provides an insight into the scientific proofs about natural bioactive substances in relation to cancer treatment, leaded by the question – do they really work?

Unraveling the molecular mechanisms and the potential chemopreventive/therapeutic properties of natural compounds in melanoma

Melanoma is the most fatal form of skin cancer. Current therapeutic approaches include surgical resection, chemotherapy, targeted therapy and immunotherapy. However, these treatment strategies are associated with development of drug resistance and severe side effects. In recent years, natural compounds have also been extensively studied for their anti-melanoma effects, including tumor growth inhibition, apoptosis induction, angiogenesis and metastasis suppression and cancer stem cell elimination. Moreover, a considerable number of studies reported the synergistic activity of phytochemicals and standard anti-melanoma agents, as well as the enhanced effectiveness of their synthetic derivatives and novel formulations. However, clinical data confirming these promising effects in patients are still scanty. This review emphasizes the anti-tumor mechanisms and potential application of the most studied natural products for melanoma prevention and treatment.

Resveratrol inhibits the proliferation of melanoma cells by modulating cell cycle

The aim of this study was to evaluate the inhibitory effects of resveratrol (RSV) in A375 and A431 melanoma cells, by assessing cell viability (CCK-8 assay), apoptosis through flow cytometer and cell morphology, cell cycle assay by flow cytometer and western blot (Cyclin D1, Rac1 and PCDH9). Our results demonstrated that RSV strongly inhibited A375 cells proliferation, by decreasing cell viability, promoting apoptosis and arresting cell cycle. Besides, to clarify the main factor - duration or concentration of RSV, the double variance analysis of independent factors was operated after Bartlett's test for homogeneity by R project. According to the outcomes obtained from statistical analyses, Cyclin D1 and PCDH9 were strongly affected by RSV duration while Rac1 was not influenced. In conclusion, RSV can inhibit A375 proliferation and trigger apoptosis by influencing cell cycle proteins; for these effects, treatment duration of RSV played more important role than concentration.

Resveratrol induces p53 in colorectal cancer through SET7/9

Resveratrol is one of the most promising phytoalexins for use as an anti-cancer agent, which is present in the skin of red grapes and berries. Resveratrol has been demonstrated to modulate a number of signalling pathways that are involved in carcinogenesis. In the present study, the function of resveratrol as a pro-apoptotic agent in colorectal cancer cell lines, including HCT116, CO115 and SW48, was investigated. The results revealed that resveratrol supressed cell viability. Additionally, resveratrol enhanced the expression of tumour protein p53 (p53) and p53 target genes, including Bcl2 associated X, apoptosis regulator and Bcl2 binding component 3 that have a pivotal role in p53-dependent apoptosis. Furthermore, treating cells with resveratrol upregulated SET domain containing lysine methyltransferase 7/9 (SET7/9) expression, which positively regulates p53 through its mono-methylation at lysine 372, compared with untreated cells. Furthermore, treating cells with resveratrol induced the expression of apoptotic markers including cleaved caspase-3 and poly (ADP-ribose) polymerases (PARP) compared with untreated cells. However, the genetic knockdown of SET7/9 by short hairpin RNA attenuated the resveratrol-driven overexpression of p53, cleaved caspase-3 and PARP. Collectively, these results reveal the molecular mechanisms by which resveratrol induces p53 stability in colon cancer that results in the activation of p53-mediated apoptosis.

Dangerous plants in dermatology: Legal and controlled

The plant and mushroom kingdoms have species used for intoxication, inebriation, or recreation. Some of these species are toxic. Given that many of these plants or substances are illegal and have histories of abuse, much of the research regarding therapeutic application is based on basic science, animal studies, and traditional use. This review examines Cannabis, Euphorbia, Ricinus, Podophyllum, Veratrum, mushrooms, and nightshades, along with resveratrol and cocaine as they relate to dermatology.

Reduction and Scavenging of Chemically Reactive Drug Metabolites by NAD(P)H:Quinone Oxidoreductase 1 and NRH:Quinone Oxidoreductase 2 and Variability in Hepatic Concentrations

Detoxicating enzymes NAD(P)H:quinone oxidoreductase 1 (NQO1) and NRH:quinone oxidoreductase 2 (NQO2) catalyze the two-electron reduction of quinone-like compounds. The protective role of the polymorphic NQO1 and NQO2 enzymes is especially of interest in the liver as the major site of drug bioactivation to chemically reactive drug metabolites. In the current study, we quantified the concentrations of NQO1 and NQO2 in 20 human liver donors and NQO1 and NQO2 activities with quinone-like drug metabolites. Hepatic NQO1 concentrations ranged from 8 to 213 nM. Using recombinant NQO1, we showed that low nM concentrations of NQO1 are sufficient to reduce synthetic amodiaquine and carbamazepine quinone-like metabolites in vitro. Hepatic NQO2 concentrations ranged from 2 to 31 μM. NQO2 catalyzed the reduction of quinone-like metabolites derived from acetaminophen, clozapine, 4′-hydroxydiclofenac, mefenamic acid, amodiaquine, and carbamazepine. The reduction of the clozapine nitrenium ion supports association studies showing that NQO2 is a genetic risk factor for clozapine-induced agranulocytosis. The 5-hydroxydiclofenac quinone imine, which was previously shown to be reduced by NQO1, was not reduced by NQO2. Tacrine was identified as a potent NQO2 inhibitor and was applied to further confirm the catalytic activity of NQO2 in these assays. While the in vivo relevance of NQO2-catalyzed reduction of quinone-like metabolites remains to be established by identification of the physiologically relevant co-substrates, our results suggest an additional protective role of the NQO2 protein by non-enzymatic scavenging of quinone-like metabolites. Hepatic NQO1 activity in detoxication of quinone-like metabolites becomes especially important when other detoxication pathways are exhausted and NQO1 levels are induced.

Comprehensive review on the antimicrobial potency of the plant polyphenol Resveratrol

Treatment of some infectious diseases are becoming more complicated because of increasing drug resistance rate and lack of proper antibiotics. Because of the rapid increase in drug-resistance trend, there is an urgent need for alternative microbicides to control infectious diseases. Resveratrol (RSV) is a small plant polyphenol that is naturally produced and distributed in 72 particular families of plants. The usage of natural derivatives such as RSV, have become popular among researchers for curing acute and chronic diseases. The purpose of the preset study was to comprehensively review and survey the antimicrobial potency of RSV. The present study demonstrates RSV as a natural antimicrobial agent.

Inhibitory Effects of Oligostilbenoids from the Bark of Shorea roxburghii on Malignant Melanoma Cell Growth: Implications for Novel Topical Anticancer Candidates

Human malignant melanomas remain associated with dismal prognosis due to their resistance to apoptosis and chemotherapy. There is growing interest in plant oligostilbenoids owing to their pleiotropic biological activities, including anti-inflammatory, antioxidant, and anticancer effects. Recent studies have demonstrated that resveratrol, a well-known stilbenoid from red wine, exhibits cell cycle-disrupting and apoptosis-inducing activities on melanoma cells. The objective of our study was to evaluate the anti-melanoma effect of oligostilbenoids isolated from the bark of Shorea roxburghii. Among the isolates, four resveratrol oligomers, i.e., (-)-hopeaphenol, vaticanol B, hemsleyanol D, and (+)-α-viniferin, possessed more potent antiproliferative action than did resveratrol against SK-MEL-28 melanoma cells. Cell cycle analysis revealed that (-)-hopeaphenol, hemsleyanol D, and (+)-α-viniferin arrested cell division cycle at the G1 phase, whereas vaticanol B had little effect on the cell cycle. In addition, cell proliferation assay also revealed that (+)-α-viniferin induced DNA damage followed by induction of apoptosis in SK-MEL-28 cells, which was confirmed by an increased expression of γ-H2AX and cleaved caspase-3, respectively. The compounds vaticanol B, hemsleyanol D, and resveratrol significantly increased the expression of p21, suggesting that they are able to block cell cycle progression. Moreover, these oligostilbenoids downmodulated cylin D1 expression and extracellular signal-regulated kinase (ERK) activation. Furthermore, hemsleyanol D, (+)-α-viniferin, and resveratrol significantly decreased the expression of cyclin B1, which could also suppress cell cycle progression. The present study thus suggests that these plant oligostilbenoids are effective as therapeutic or chemopreventive agents against melanoma.

Use of Polyphenolic Compounds in Dermatologic Oncology

Polyphenols are a widely used class of compounds in dermatology. While phenol itself, the most basic member of the phenol family, is chemically synthesized, most polyphenolic compounds are found in plants and form part of their defense mechanism against decomposition. Polyphenolic compounds, which include phenolic acids, flavonoids, stilbenes, and lignans, play an integral role in preventing the attack on plants by bacteria and fungi, as well as serving as cross-links in plant polymers. There is also mounting evidence that polyphenolic compounds play an important role in human health as well. One of the most important benefits, which puts them in the spotlight of current studies, is their antitumor profile. Some of these polyphenolic compounds have already presented promising results in either in vitro or in vivo studies for non-melanoma skin cancer and melanoma. These compounds act on several biomolecular pathways including cell division cycle arrest, autophagy, and apoptosis. Indeed, such natural compounds may be of potential for both preventive and therapeutic fields of cancer. This review evaluates the existing scientific literature in order to provide support for new research opportunities using polyphenolic compounds in oncodermatology.

Genome-wide analysis of long noncoding RNA (lncRNA) expression in colorectal cancer tissues from patients with liver metastasis

The liver is the most frequent site of metastasis in colorectal cancer (CRC), in which long noncoding RNAs (lncRNAs) may play a crucial role. In this study, we performed a genome-wide analysis of lncRNA expression to identify novel targets for the further study of liver metastasis in CRC. Samples obtained from CRC patients were analyzed using Arraystar human 8 × 60K lncRNA/mRNA v3.0 microarrays chips to find differentially expressed lncRNAs and mRNAs. The results were confirmed by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). The differentially expressed lncRNAs and mRNAs were identified through fold change filtering. Gene ontology (GO) and pathway analyses were performed using standard enrichment computational methods. In the CRC tissues from patients with liver metastasis, 2636 lncRNAs were differentially expressed, including 1600 up-regulated and 1036 down-regulated over two-fold compared with the CRC tissues without metastasis. Among the 1584 differentially expressed mRNAs, 548 were up-regulated and 1036 down-regulated. GO and pathway analysis of the up-regulated and down-regulated mRNAs yielded different results. The up-regulated mRNAs were associated with single-organism process (biological process), membrane part (cellular component), and transporter activity (molecular function), whereas the down-regulated mRNAs were associated with cellular process, membrane, and binding, respectively. In the pathway analysis, 27 gene pathways associated with the up-regulated mRNAs and 51 gene pathways associated with the down-regulated mRNAs were targeted. The significant changes in NQO2 (NM_000904) mRNA and six associated lncRNAs were selected for validation by qRT-PCR. Aberrantly expressed lncRNAs may play an important role in the liver metastasis of CRC. The further study can provide useful insights into the biology and, ultimately, the prevention of liver metastasis.

Targeting drivers of melanoma with synthetic small molecules and phytochemicals

Melanoma is the least common form of skin cancer, but it is responsible for the majority of skin cancer deaths. Traditional therapeutics and immunomodulatory agents have not shown much efficacy against metastatic melanoma. Agents that target the RAS/RAF/MEK/ERK (MAPK) signaling pathway - the BRAF inhibitors vemurafenib and dabrafenib, and the MEK1/2 inhibitor trametinib - have increased survival in patients with metastatic melanoma. Further, the combination of dabrafenib and trametinib has been shown to be superior to single agent therapy for the treatment of metastatic melanoma. However, resistance to these agents develops rapidly. Studies of additional agents and combinations targeting the MAPK, PI3K/AKT/mTOR (PI3K), c-kit, and other signaling pathways are currently underway. Furthermore, studies of phytochemicals have yielded promising results against proliferation, survival, invasion, and metastasis by targeting signaling pathways with established roles in melanomagenesis. The relatively low toxicities of phytochemicals make their adjuvant use an attractive treatment option. The need for improved efficacy of current melanoma treatments calls for further investigation of each of these strategies. In this review, we will discuss synthetic small molecule inhibitors, combined therapies and current progress in the development of phytochemical therapies.

The emerging immunological role of post-translational modifications by reactive nitrogen species in cancer microenvironment

Under many inflammatory contexts, such as tumor progression, systemic and peripheral immune response is tailored by reactive nitrogen species (RNS)-dependent post-translational modifications, suggesting a biological function for these chemical alterations. RNS modify both soluble factors and receptors essential to induce and maintain a tumor-specific immune response, creating a “chemical barrier” that impairs effector T cell infiltration and functionality in tumor microenvironment and supports the escape phase of cancer. RNS generation during tumor growth mainly depends on nitric oxide production by both tumor cells and tumor-infiltrating myeloid cells that constitutively activate essential metabolic pathways of l-arginine catabolism. This review provides an overview of the potential immunological and biological role of RNS-induced modifications and addresses new approaches targeting RNS either in search of novel biomarkers or to improve anti-cancer treatment.

Chemoprevention of skin melanoma: facts and myths

Melanoma is the most dangerous type of skin cancer. Despite the rise of public awareness, the incidence rate among the white population has been rising constantly for several decades. Systematic improvement in knowledge about the biology of pigment cells and molecular mechanisms of their neoplastic transformation has enhanced the possibility of melanoma chemoprevention. Hence, chemopreventive agents that prevent, inhibit, or reverse melanoma development are being investigated intensively. Among synthetic compounds, especially well studied are lipid-lowering drugs and cyclooxygenase inhibitors. Substances found in everyday diet, such as genistein, apigenin, quercetin, resveratrol, and curcumin may also have potential chemopreventive qualities. However, studies examining the chemopreventive activity of these compounds have shown widely varying results. Early reports on the possible chemopreventive activity of statins and fibrates were not proved by the results of randomized clinical trials. Similarly, case-control studies examining the influence of NSAIDs on the risk of melanoma do not confirm the antitumor activity of cyclooxygenase inhibitors. Further clinical trials involving carefully selected target populations as well as the identification of specific biomarkers of prognostic and predictive value seem to be essential for the evaluation of the chemopreventive activity of the studied substances.

Molecular pathways: inflammation-associated nitric-oxide production as a cancer-supporting redox mechanism and a potential therapeutic target

It is widely accepted that many cancers express features of inflammation, driven by both microenvironmental cells and factors, and the intrinsic production of inflammation-associated mediators from malignant cells themselves. Inflammation results in intracellular oxidative stress with the ultimate biochemical oxidants composed of reactive nitrogens and oxygens. Although the role of inflammation in carcinogensis is well accepted, we now present data showing that inflammatory processes are also active in the maintenance phase of many aggressive forms of cancer. The oxidative stress of inflammation is proposed to drive a continuous process of DNA adducts and crosslinks, as well as posttranslational modifications to lipids and proteins that we argue support growth and survival. In this perspective, we introduce data on the emerging science of inflammation-driven posttranslational modifications on proteins responsible for driving growth, angiogenesis, immunosuppression, and inhibition of apoptosis. Examples include data from human melanoma, breast, head and neck, lung, and colon cancers. Fortunately, numerous antioxidant agents are clinically available, and we further propose that the pharmacologic attenuation of these inflammatory processes, particularly the reactive nitrogen species, will restore the cancer cells to an apoptosis-permissive and growth-inhibitory state. Our mouse model data using an arginine antagonist that prevents enzymatic production of nitric oxide directly supports this view. We contend that selected antioxidants be considered as part of the cancer treatment approach, as they are likely to provide a novel and mechanistically justified addition for therapeutic benefit.

Melatonin induces transcriptional regulation of Bim by FoxO3a in HepG2 cells

Background:

Melatonin induces apoptosis in many different cancer cell lines, including hepatocellular carcinoma cells. However, the responsible pathways have not been clearly elucidated. A member of the forkhead transcription factors' family, FoxO3a, has been implicated in the expression of the proapoptotic protein Bim (a Bcl-2-interacting mediator of cell death). In this study, we used human HepG2 liver cancer cells as an in vitro model to investigate whether melatonin treatment induces Bim through regulation by the transcription factor FoxO3a.

Methods:

Cytotoxicity of melatonin was compared in HepG2 hepatoblastoma cells and primary human hepatocytes. Proapoptotic Bim expression was analysed by reverse transcriptase–polymerase chain reaction and western blot. Reporter gene assays and chromatin immunoprecipitation assays were performed to analyse whether FoxO3a transactivates the Bim promoter. Small interfering RNA (siRNA) was used to study the role of FoxO3a in Bim expression. Immunofluorescence was performed to analyse FoxO3a localisation in HepG2 cells.

Results:

Melatonin treatment induces apoptosis in HepG2 cells, but not in primary human hepatocytes. The proapoptotic effect was mediated by increased expression of the BH3-only protein Bim. During melatonin treatment, we observed increased transcriptional activity of the forkhead-responsive element and could demonstrate that FoxO3a binds to a specific sequence within the Bim promoter. Furthermore, melatonin reduced phosphorylation of FoxO3a at Thr³² and Ser²⁵³, and induced its increased nuclear localisation. Moreover, silencing experiments with FoxO3a siRNA prevented Bim upregulation.

Conclusion:

This study shows that melatonin can induce apoptosis in HepG2 hepatocarcinoma cells through the upregulation of proapoptotic Bim mediated by nuclear translocation and activation of the transcription factor FoxO3a.

Transient transfection of a wild-type p53 gene triggers resveratrol-induced apoptosis in cancer cells

Resveratrol is a promising chemopreventive agent that mediates many cellular targets involved in cancer signaling pathways. p53 has been suggested to play a role in the anticancer properties of resveratrol. We investigated resveratrol-induced cytotoxicity in H1299 cells, which are non-small lung cancer cells that have a partial deletion of the gene that encodes the p53 protein. The results for H1299 cells were compared with those for three cell lines that constitutively express wild-type p53: breast cancer MCF-7, adenocarcinomic alveolar basal epithelia A549 and non-small lung cancer H460. Cell viability assays revealed that resveratrol reduced the viability of all four of these cell lines in a dose- and time-dependent manner. MCF-7, A549 and H460 cells were more sensitive to resveratrol than were H1299 cells when exposed to the drug for 24 h at concentrations above 100 µM. Resveratrol also increased the p53 protein levels in MCF-7 cells without altering the p53 mRNA levels, suggesting a post-translational modulation of the protein. The resveratrol-induced cytotoxicity in these cells was partially mediated by p53 and involved the activation of caspases 9 and 7 and the cleavage of PARP. In H1299 cells, resveratrol-induced cytotoxicity was less pronounced and (in contrast to MCF-7 cells) cell death was not accompanied by caspase activation. These findings are consistent with the observation that MCF-7 cells were positively labeled by TUNEL following exposure to 100 µM resveratrol whereas H1299 cells under similar conditions were not labeled by TUNEL. The transient transfection of a wild-type p53-GFP gene caused H1299 cells to become more responsive to the pro-apoptotic properties of resveratrol, similarly to findings in the p53-positive MCF-7 cells. Our results suggest a possible therapeutic strategy based on the use of resveratrol for the treatment of tumors that are typically unresponsive to conventional therapies because of the loss of normal p53 function.

Melatonin modulation of intracellular signaling pathways in hepatocarcinoma HepG2 cell line: role of the MT1 receptor

Melatonin reduces proliferation in many different cancer cell lines. However, studies on the oncostatic effects of melatonin in hepatocarcinoma are limited. We have previously demonstrated that melatonin administration induces cycle arrest, apoptosis, and changes in the expression of its specific receptors in HepG2 human hepatocarcinoma cells. In this study, we used the receptor antagonist luzindole to assess the contribution of MT1 melatonin membrane receptor to melatonin effects on cell viability, mitogen-activated protein kinase (MAPKs) activation, and cAMP levels. Additionally, effects of MT1 inhibition on mRNA levels of cytosolic quinone reductase type-2 (NQO2) receptor and nuclear retinoic acid-related orphan receptor alpha (RORα) were tested. Melatonin, at 1000 and 2500 μm, significantly reduced cell viability. Pre-incubation with luzindole partially inhibited the effects of melatonin on cell viability. Melatonin at 2500 μm significantly reduced cAMP levels, and this effect was partially blocked by luzindole. Both melatonin concentrations increased the expression of phosphorylated p38, ERK, and JNK. ERK activation was completely abolished in the presence of luzindole. NQO2 but not RORα mRNA level significantly increased in luzindole-treated cells. Results obtained provide evidence that the melatonin effects on cell viability and proliferation in HepG2 cells are partially mediated through the MT1 membrane receptor, which seems to be related also with melatonin modulation of cAMP and ERK activation. This study also highlights a possible interplay between MT1 and NQO2 melatonin receptors in liver cancer cells.

Design and synthesis of resveratrol-based nitrovinylstilbenes as antimitotic agents

A new series of resveratrol analogues was designed, synthesized, and demonstrated to be tubulin polymerization inhibitors. Most of these compounds exhibited antiproliferative activity and inhibited in vitro tubulin polymerization effectively at concentrations of 4.4-68.1 and 17-62 μM, respectively. Flow cytometry studies showed that compounds 7c, 7e, and 7g arrested cells in the G2/M phase of the cell cycle. Immunocytochemistry revealed loss of intact microtubule structure in cells treated with 7c and 7e. Docking of compounds 7c and 7e with tubulin suggested that the A-ring of the compounds occupies the colchicine binding site of tubulin, which coordinates with Cys241, Leu242, Ala250, Val318, Val328, and I378, and that the nitrovinyl side chain forms two hydrogen bonds with the main loop of the β-chain at Asn249 and Ala250.

Anti-tumor and immunomodulatory activity of resveratrol in vitro and its potential for combining with cancer immunotherapy

We evaluated the anti-tumor effect of Resveratrol (RV) on M21 and NXS2 tumor cell lines and its immunosuppressive activity on human and murine immune cells to determine the potential for combining RV and immunotherapy. In vitro, concentrations of RV≥25 mcM, inhibited cell proliferation, blocked DNA synthesis and induced G1 phase arrest in tumor and immune cells. RV at 12-50 mcM inhibited antibody dependent cell mediated cytotoxicity (ADCC) of tumor cells facilitated by the hu14.18-IL2 immunocytokine (IC). The in vivo anti-tumor and immunomodulating activity of RV given systemically were assessed in mice. Results showed that this RV regimen inhibited the growth of NXS2 tumors in vivo but did not appear to interfere with blood cell count, splenocyte or macrophage function. Thus, RV may be a candidate for combining with immunotherapy.

Botanicals for the prevention and treatment of cutaneous melanoma

Cutaneous melanoma, a cancer of melanocytes, when detected at later stages is arguably one of the most lethal cancers and the cause of more years of lost life than any other cancer among young adults. There is no standard therapy for advanced-stage melanoma and the median survival time for patients with metastatic melanoma is <1 yr. An urgent need for novel strategies against melanoma has directed research towards the development of new chemotherapeutic and biologic agents that can target the tumor by several different mechanisms. Recently, several dietary agents are being investigated for their role in the prevention and treatment of various forms of cancer and may represent the future modality of the treatment. Here, we have reviewed emerging data on botanicals that are showing promise for their potential inhibitory effect against cutaneous melanoma.

X-ray structural studies of quinone reductase 2 nanomolar range inhibitors

Quinone reductase 2 (QR2) is one of two members comprising the mammalian quinone reductase family of enzymes responsible for performing FAD mediated reductions of quinone substrates. In contrast to quinone reductase 1 (QR1) which uses NAD(P)H as its co-substrate, QR2 utilizes a rare group of hydride donors, N-methyl or N-ribosyl nicotinamide. Several studies have linked QR2 to the generation of quinone free radicals, several neuronal degenerative diseases, and cancer. QR2 has been also identified as the third melatonin receptor (MT3) through in cellulo and in vitro inhibition of QR2 by traditional MT3 ligands, and through recent X-ray structures of human QR2 (hQR2) in complex with melatonin and 2-iodomelatonin. Several MT3 specific ligands have been developed that exhibit both potent in cellulo inhibition of hQR2 nanomolar, affinity for MT3. The potency of these ligands suggest their use as molecular probes for hQR2. However, no definitive correlation between traditionally obtained MT3 ligand affinity and hQR2 inhibition exists limiting our understanding of how these ligands are accommodated in the hQR2 active site. To obtain a clearer relationship between the structures of developed MT3 ligands and their inhibitory properties, in cellulo and in vitro IC₅₀ values were determined for a representative set of MT3 ligands (MCA-NAT, 2-I-MCANAT, prazosin, S26695, S32797, and S29434). Furthermore, X-ray structures for each of these ligands in complex with hQR2 were determined allowing for a structural evaluation of the binding modes of these ligands in relation to the potency of MT3 ligands.

Resveratrol: a cardioprotective substance

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.

Nutrition and melanoma prevention

Melanoma has continued to rise in incidence despite public efforts to promote sun protection behaviors. Because sunscreen use does not completely prevent skin cancer induced by ultraviolet radiation, additional chemopreventive methods for protecting against and reversing the effects of ultraviolet photodamage need evaluation. Recent years have brought increased interest in dietary factors, such as natural botanicals and vitamins, for the prevention of melanoma. This contribution provides a narrative review of the relevant, nutrition-related literature found by searching the keywords "melanoma chemoprevention," "nutrition and melanoma," "dietary botanicals and melanoma prevention," "green tea and melanoma," "vitamin D and melanoma," and "vitamin E and melanoma" in the PubMed database. Although randomized controlled trials of humans are lacking, basic science and epidemiologic studies show promising benefits of many natural products in chemoprevention for melanoma. Future studies, hopefully, will yield concrete answers and clarify the role of commonly available dietary nutrients in melanoma chemoprevention.

Screening natural products for inhibitors of quinone reductase-2 using ultrafiltration LC-MS

Inhibitors of quinone reductase-2 (NQO2; QR-2) can have antimalarial activity and antitumor activities or can function as chemoprevention agents by preventing the metabolic activation of toxic quinones such as menadione. To expedite the search for new natural product inhibitors of QR-2, we developed a screening assay based on ultrafiltration liquid chromatography-mass spectrometry that is compatible with complex samples such as bacterial or botanical extracts. Human QR-2 was prepared recombinantly, and the known QR-2 inhibitor, resveratrol, was used as a positive control and as a competitive ligand to eliminate false positives. Ultrafiltration LC-MS screening of extracts of marine sediment bacteria resulted in the discovery of tetrangulol methyl ether as an inhibitor of QR-2. When applied to the screening of hop extracts from the botanical, Humulus lupulus L., xanthohumol and xanthohumol D were identified as ligands of QR-2. Inhibition of QR-2 by these ligands was confirmed using a functional enzyme assay. Furthermore, binding of xanthohumol and xanthohumol D to the active site of QR-2 was confirmed using X-ray crystallography. Ultrafiltration LC-MS was shown to be a useful assay for the discovery of inhibitors of QR-2 in complex matrixes such as extracts of bacteria and botanicals.

Anti-inflammatory effects of resveratrol: possible role in prevention of age-related cardiovascular disease

Cardiovascular diseases are the most common cause of death among the elderly in the Western world. Resveratrol (3,5,4'-trihydroxystilbene) is a plant-derived polyphenol that was shown to exert diverse anti-aging activity mimicking some of the molecular and functional effects of caloric restriction. This mini-review focuses on the molecular and cellular mechanisms activated by resveratrol in the vascular system, and explores the links between its anti-oxidative and anti-inflammatory effects, which could be exploited for the prevention or amelioration of vascular aging in the elderly.

Resveratrol induces cell-cycle disruption and apoptosis in chemoresistant B16 melanoma

Resveratrol, a naturally occurring polyphenol, has been shown to possess chemopreventive activities. In this study, we show that resveratrol (0-500 microM) inhibits the growth of a doxorubicin-resistant B16 melanoma cell subline (B16/DOX) (IC(50) = 25 microM after 72 h, P < 0.05). This was accomplished by imposing an artificial checkpoint at the G(1)-S phase transition, as demonstrated by cell-cycle analysis and down-regulation of cyclin D1/cdk4 and increased of p53 expression level. The G(1)-phase arrest of cell cycle in resveratrol-treated (10-100 microM) B16/DOX cells was followed by the induction of apoptosis, which was revealed by pyknotic nuclei and fragmented DNA. Resveratrol also potentiated at subtoxic dose (25 microM for 24 h) doxorubicin cytotoxicity in the chemoresistant B16 melanoma (P < 0.01). When administered to mice, resveratrol (12.5 mg/kg) reduced the growth of an established B16/DOX melanoma and prolonged survival (32% compared to untreated mice). All these data support a potential use of resveratrol alone or in combination with other chemotherapeutic agents in the management of chemoresistant tumors.

Resveratrol regulates human adipocyte number and function in a Sirt1-dependent manner

BACKGROUND

Caloric restriction leads to retardation of the aging processes and to longer life in many organisms. This effect of caloric restriction can be mimicked by resveratrol, a natural plant product present in grapes and red wine, which is known as a potent activator of sirtuin 1 [silent mating type information regulation 2 homolog 1 (Sirt1)].

OBJECTIVES

One main effect of caloric restriction in mammals is a reduction of body fat from white adipose tissue. We sought to identify the effects of resveratrol on fat cell biology and to elucidate whether Sirt1 is involved in resveratrol-mediated changes.

DESIGN

Human Simpson-Golabi-Behmel syndrome preadipocytes and adipocytes were used to study proliferation, adipogenic differentiation, glucose uptake, de novo lipogenesis, and adipokine secretion. Sirt1-deficient human preadipocytes were generated by using a lentiviral small hairpin RNA system to study the role of Sirt1 in resveratrol-mediated changes.

RESULTS

Resveratrol inhibited preadipocyte proliferation and adipogenic differentiation in a Sirt1-dependent manner. In human adipocytes, resveratrol stimulated basal and insulin-stimulated glucose uptake. De novo lipogenesis was inhibited in parallel with a down-regulation of lipogenic gene expression. Furthermore, resveratrol down-regulated the expression and secretion of interleukin-6 and interleukin-8. Sirt1 was only partially responsible for the regulation of resveratrol-mediated changes in adipokine secretion.

CONCLUSIONS

Taken together, our data suggest that resveratrol influences adipose tissue mass and function in a way that may positively interfere with the development of obesity-related comorbidities. Thus, our findings open up the new perspective that resveratrol-induced intracellular pathways could be a target for prevention or treatment of obesity-associated endocrine and metabolic adverse effects.

Current research and development of chemotherapeutic agents for melanoma

Cutaneous malignant melanoma is the most lethal form of skin cancer and an increasingly common disease worldwide. It remains one of the most treatment-refractory malignancies. The current treatment options for patients with metastatic melanoma are limited and in most cases non-curative. This review focuses on conventional chemotherapeutic drugs for melanoma treatment, by a single or combinational agent approach, but also summarizes some potential novel phytoagents discovered from dietary vegetables or traditional herbal medicines as alternative options or future medicine for melanoma prevention. We explore the mode of actions of these natural phytoagents against metastatic melanoma.

3,3',4,4',5,5'-hexahydroxystilbene impairs melanoma progression in a metastatic mouse model

Stilbenes comprise a group of polyphenolic compounds, which exert inhibitory effects on various malignancies. The aim of this study was to evaluate the antitumor effects of a previously unreported stilbene derivative-3,3',4,4',5,5'-hexahydroxystilbene, termed M8-on human melanoma cells. Cell-cycle analysis of the metastatic melanoma cell line M24met showed that M8 treatment induces G(2)/M arrest accompanied with a dose- and time-dependent upregulation of p21 and downregulation of CDK-2 and leads to apoptosis. M8 induces the expression of phosphorylated p53, proteins involved in the mismatch repair machinery (MSH6, MSH2, and MLH1) and a robust tail moment in a comet assay. In addition, M8 inhibited cell migration in Matrigel assays. Shotgun proteomics and western analysis showed the regulation among others of paxillin, integrin-linked protein kinase, p21-activated kinase, and ROCK-1 indicating that M8 inhibits mesenchymal and amoeboid cell migration. These in vitro data were confirmed in vivo in a metastatic human melanoma severe combined immunodeficient (SCID) mouse model. We showed that M8 significantly impairs tumor growth. M8 also interfered with the metastatic process, as M8 treatment prevented the metastatic spread of melanoma cells to distant lymph nodes in vivo. In summary, M8 exerts strong antitumor effects with the potential to become a new drug for the treatment of metastatic melanoma.

Resveratrol: its biologic targets and functional activity

The polyphenolic phytoalexin resveratrol (RSV) and its analogues have received tremendous attention over the past couple of decades because of a number of reports highlighting their benefits in vitro and in vivo in a variety of human disease models, including cardio- and neuroprotection, immune regulation, and cancer chemoprevention. These studies have underscored the high degree of diversity in terms of the signaling networks and cellular effector mechanisms that are affected by RSV. The activity of RSV has been linked to cell-surface receptors, membrane signaling pathways, intracellular signal-transduction machinery, nuclear receptors, gene transcription, and metabolic pathways. The promise shown by RSV has prompted heightened interest in studies aimed at translating these observations to clinical settings. In this review, we present a comprehensive account of the basic chemistry of RSV, its bioavailability, and its multiple intracellular target proteins and signaling pathways.

Changes in the expression of melatonin receptors induced by melatonin treatment in hepatocarcinoma HepG2 cells

Hepatocellular carcinoma (HCC) is one of the most common cancers and its incidence is increasing worldwide. Melatonin, an indoleamine hormone, exerts anti-oxidant, immunomodulatory, anti-aging, and antitumor effects. Previous studies have shown that melatonin can act through specific receptors, including MT(1), MT(2), MT(3) receptors as well as a nuclear receptor belonging to the orphan nuclear receptor family. Recently, we have described their role in the oncostatic and pro-apoptotic effects of melatonin on HepG2 human HCC cells. However, the potential role of the different melatonin cellular receptors on its antiproliferative effects remains unknown. In the present study, we examined the effect of melatonin treatment on HepG2 human HCC cells, analyzing cell cycle arrest and melatonin receptor expression. Melatonin was administered for 2, 4, and 6 days at 1000 or 2500 microm. Melatonin induced a dose- and time-dependent inhibition on cell proliferation. This treatment caused an alteration in the cell cycle, with an increase in the number of cells in G(2)/M phase at both 1000 and 2500 microm melatonin concentrations, and a significant increase on S phase cell percentage by the highest dose. Furthermore, increases in protein expression of MT(1), MT(3), and retinoic acid-related orphan receptor-alpha were found after melatonin treatments. These increases were coincident with a significant induction in the expression of p21 protein, which negatively regulates cell cycle progression. Our results confirm the antitumor effect of melatonin in HCC cells, suggesting that its oncostatic properties are related, at least in part, to changes on the expression of their different subtypes of receptors.

Resveratrol analog trans 3,4,5,4'-tetramethoxystilbene (DMU-212) mediates anti-tumor effects via mechanism different from that of resveratrol

PURPOSE

Resveratrol is a well-known chemopreventive and chemotherapeutic agent. Among all of the resveratrol analogs synthesized, 3,4,5,4'-tetramethoxystilbene (DMU-212) shows high activity and selectivity against various cancer cell types. The objective of this study is to investigate why DMU-212 has higher anti-tumor activity than resveratrol.

METHODS

The effects of DMU-212 and resveratrol on cell viability, cell cycle, Stat3 activation, and microtubule dynamic were investigated and compared using MTT assay, cell cycle analysis, Western blot, tubulin polymerization assay, respectively, in MDA-MB-435 and MCF-7 human breast cancer cells.

RESULTS

Compared to resveratrol, DMU-212 exerted a significantly higher growth inhibition in both cell lines. Further studies demonstrated that DMU-212 acted via different mechanisms from resveratrol. First, DMU-212 induced predominantly G2/M arrest whereas resveratrol induced G0/G1 arrest in both cell lines. Correlating with these findings, resveratrol induced more dramatic changes in the expression of Cyclin D1 compared to DMU-212. Second, DMU-212 induced apoptosis and reduced the expression of multiple anti-apoptotic proteins more appreciably than resveratrol. Third, while both agents inhibited Stat3 phosphorylation, treatments of DMU-212 but not resveratrol led to a significant increase in tubulin polymerization. The higher sensitivity to DMU-122 in MDA-MB-435 correlated with the more prominent effects seen in these parameters in this cell line, as compared to MCF7.

CONCLUSION

Compared to resveratrol, the novel stilbene derivative, DMU-212, had higher anti-tumor effects, which are likely owing to its modulation of multiple cellular targets.

Synthesis of α-Aminoalkyl Phosphonate Derivatives of Resveratrol as Potential Antitumour Agents

Several α-aminoalkyl phosphonate derivatives of resveratrol were first prepared by partial synthesis from resveratrol. Antitumour activities of the synthesized compounds were determined against a human nasopharyngeal epidermoid tumour cell line KB and a human normal cell line L02 in vitro. The results indicated that these compounds showed good cytotoxic activity against KB but weak cytotoxic activity against L02. Compounds 5c and 5d showed significant cytotoxic activity against KB, with median inhibition concentration (IC50) values of 0.4 μM and 0.9 μM, respectively. On the basis of the biological results, the structure–activity relationship is discussed concisely. The potent antitumour activities shown by 5c and 5d make these resveratrol phosphonate derivatives of great interest for further investigations.

Deficiency of NRH:quinone oxidoreductase 2 differentially regulates TNF signaling in keratinocytes: up-regulation of apoptosis correlates with down-regulation of cell survival kinases

NRH:quinone oxidoreductase 2 (NQO2) is a cytosolic flavoprotein that catalyzes the two-electron reduction of quinones and quinoid compounds to hydroquinones. Although the role of a homologue, NAD(P)H:quinone oxidoreductase 1 (NQO1), is well defined in oxidative stress, neoplasia, and carcinogenesis, little is known about the mechanism of actions of NQO2 in these cellular responses. Whether NQO2 has any role in tumor necrosis factor (TNF) signaling was investigated using keratinocytes derived from wild-type and NQO2 knockout (NQO2-/-) mice. Although exposure of wild-type cells to TNF led to activation of nuclear factor-kappaB (NF-kappaB) and IkappaBalpha kinase, IkappaBalpha degradation, p65 phosphorylation, and p65 nuclear translocation, this cytokine had no effect on NQO2-/- cells. Deletion of NQO2 also abolished TNF-induced c-Jun NH2-terminal kinase, Akt, p38, and p44/p42 mitogen-activated protein kinase activation. The induction of various antiapoptotic gene products (MMP-9, cyclin D1, COX-2, IAP1, IAP2, Bcl-2, cFLIP, and XIAP) by TNF was also abolished in NQO2-/- cells. This correlated with potentiation of TNF-induced apoptosis as indicated by cell viability, Annexin V staining, and caspase activation. In agreement with this, we also found that TNF activated NQO2, and NQO2-specific small interfering RNA abrogated the TNF-induced NQO2 activity and NF-kappaB activation. Overall, our results indicate that deletion of NQO2 plays a differential role in TNF signaling pathway: by suppressing cell survival signals and potentiating TNF-induced apoptosis.

Resveratrol: a review of preclinical studies for human cancer prevention

The search for novel and effective cancer chemopreventive agents has led to the identification of various naturally occurring compounds one of which is resveratrol (trans-3,4',5-trihydroxystilbene), a phytoalexin derived from the skin of grapes and other fruits. Resveratrol is known to have potent anti-inflammatory and antioxidant effects and to inhibit platelet aggregation and the growth of a variety of cancer cells. Its potential chemopreventive and chemotherapeutic activities have been demonstrated in all three stages of carcinogenesis (initiation, promotion, and progression), in both chemically and UVB-induced skin carcinogenesis in mice, as well as in various murine models of human cancers. Evidence from numerous in vitro and in vivo studies has confirmed its ability to modulate various targets and signaling pathways. This review discusses the current preclinical and mechanistic data available and assesses resveratrol's anticancer effects to support its potential as an anticancer agent in human populations.

Predicting the physiological relevance of in vitro cancer preventive activities of phytochemicals

There is growing interest in the ability of phytochemicals to prevent chronic diseases, such as cancer and heart disease. However, some of these agents have poor bioavailability and many of the in-depth studies into their mechanisms of action have been carried out in vitro using doses which are unachievable in humans. In order to optimize the design of chemopreventive treatment, it is important to determine which of the many reported mechanisms of action are clinically relevant. In this review we consider the physiologically achievable doses for a few of the best studied agents (indole-3-carbinol, diindolylmethane, curcumin, epigallocatechin-3-gallate and resveratrol) and summarize the data derived from studies using these low concentrations in cell culture. We then cite examples of in vitro effects which have been observed in vivo. Finally, the ability of agent combinations to act synergistically or antagonistically is considered. We conclude that each of the compounds shows an encouraging range of activities in vitro at concentrations which are likely to be physiologically relevant. There are also many examples of in vivo studies which validate in vitro observations. An important consideration is that combinations of agents can result in significant activity at concentrations where any single agent is inactive. Thus, for each of the compounds reviewed here, in vitro studies have provided useful insights into their mechanisms of action in humans. However, data are lacking on the full range of activities at low doses in vitro and the benefits or otherwise of combinations in vivo.

Toxicogenomics of A375 human malignant melanoma cells

Toxicogenomics applications are increasingly applied to the evaluation of preclinical drug safety, and to explain toxicities associated with compounds at the mechanism level. In this review, we aim to describe the application of toxicogenomics tools for studying the genotoxic effect of active compounds on the gene-expression profile of A375 human malignant melanoma cells, through the other molecular functions of target genes, regulatory pathways and mechanisms of malignant melanomas. It also includes the current systems biology approaches, which are very useful for analyzing the biological system and understanding the entire mechanisms of malignant melanomas. We believe that this review would be very potent and useful for studying the toxicogenomics of A375 melanoma cells, and for further diagnostic and therapeutic applications.

Resveratrol modulates mRNA transcripts of genes related to redox metabolism and cell proliferation in non-small-cell lung carcinoma cells

Resveratrol is a polyphenolic chemopreventive agent that has been shown to influence cellular redox reactions. As a systematic approach to elucidating the complex effects of resveratrol on eukaryotic cells, we studied its dose-dependent effects on the transcript levels of genes and activities of enzymes related to redox metabolism, cell cycle regulation, and apoptotic cascades in the cancer cell line A549. Glutathione peroxidase (GPx)1 mRNA levels, as well as GPx and thioredoxin reductase (TrxR) activities, were significantly increased after resveratrol treatment, whereas total glutathione concentrations decreased. Increased transcript levels were also detected for selenophosphate synthetase 2 and superoxide dismutase 2. However, mRNA levels of thioredoxin, TrxR, glutathione reductase, glutathione S-transferase, superoxide dismutase 1, and catalase were not altered. Among the 12 genes studied that are related to the cell cycle, differentiation and apoptosis, mRNA levels of six genes, including P53, FAS, and BCL2, were upregulated, while the mRNA level of survivin was reduced. The results suggest that GPx and other selenoproteins are important targets of resveratrol. Furthermore, genes supporting cell survival and differentiation, as well as genes involved in proliferation inhibition and apoptosis, are induced by resveratrol, resulting in a delicate balance that is likely to contribute to the chemopreventive effects of resveratrol.

Bifunctional effect of resveratrol on the expression of ErbB2 in human breast cancer cell

This study evaluated the effect of resveratrol on the expression of ErbB2 in a human breast cancer cell line, MCF-7. Low concentrations of resveratrol (1-10microM) reduced the basal expression level of ErbB2 in MCF-7 cells cultured in an estrogen-free medium. When cells were cultured in a medium containing estrogen, resveratrol increased the ErbB2 protein levels in a dose-dependent manner. Resveratrol increased the luciferase reporter gene activity in cells transfected with the -756bp flanking region of the human erbB2 gene. Resveratrol increased the nuclear levels of AP-2alpha and AP-2gamma, and the induction of the luciferase reporter gene by resveratrol was inhibited by a mutation of two AP-2 binding sites in the promoter region of the human erbB2 gene. Blocking the ERK, p38 kinase or PI3-kinase activity had no effect on the resveratrol-inducible transactivation of the erbB2 gene and the ErbB2 expression level.