Resveratrol analog, HS-1793 enhance anti-tumor immunity by reducing the CD4+CD25+ regulatory T cells in FM3A tumor bearing mice

Prevention and Co-Management of Breast Cancer-Related Osteoporosis Using Resveratrol

Breast cancer (BC) is currently one of the most common cancers in women worldwide with a rising tendency. Epigenetics, generally inherited variations in gene expression that occur independently of changes in DNA sequence, and their disruption could be one of the main causes of BC due to inflammatory processes often associated with different lifestyle habits. In particular, hormone therapies are often indicated for hormone-positive BC, which accounts for more than 50-80% of all BC subtypes. Although the cure rate in the early stage is more than 70%, serious negative side effects such as secondary osteoporosis (OP) due to induced estrogen deficiency and chemotherapy are increasingly reported. Approaches to the management of secondary OP in BC patients comprise adjunctive therapy with bisphosphonates, non-steroidal anti-inflammatory drugs (NSAIDs), and cortisone, which partially reduce bone resorption and musculoskeletal pain but which are not capable of stimulating the necessary intrinsic bone regeneration. Therefore, there is a great therapeutic need for novel multitarget treatment strategies for BC which hold back the risk of secondary OP. In this review, resveratrol, a multitargeting polyphenol that has been discussed as a phytoestrogen with anti-inflammatory and anti-tumor effects at the epigenetic level, is presented as a potential adjunct to both support BC therapy and prevent osteoporotic risks by positively promoting intrinsic regeneration. In this context, resveratrol is also known for its unique role as an epigenetic modifier in the regulation of essential signaling processes-both due to its catabolic effect on BC and its anabolic effect on bone tissue.

Comprehensive and critical view on the anti-inflammatory and immunomodulatory role of natural phenolic antioxidants

The immune response encompasses innate and adaptive immunity, each with distinct and specific activities. The innate immune system is constituted by phagocytic cells, macrophages, monocytes and neutrophils, the cascade system, and different classes of receptors such as toll-like receptors that are exploited by the innate immune cells. The adaptive immune system is antigen-specific, encompassing memory lymphocytes and the corresponding specific receptors. Inflammation is understood as an activation of different signaling pathways such as toll-like receptors or nuclear factor kappa-light-chain-enhancer of activated B cells, with an increase in nitric oxide, inflammatory cytokines and chemokines. Increased oxidative stress has been identified as main source of chronic inflammation. Phenolic antioxidants modulate the activities of lymphocytes and macrophages by impacting cytokines and nitric oxide release, exerting anti-inflammatory effect. The nuclear-factor kappa-light-chain-enhancer of activated B cells signaling pathway and the mitogen-activated protein kinase pathway are targeted, alongside an increase in nuclear factor erythroid 2-related factor mediated antioxidant response, triggering the activity of antioxidant enzymes. The inhibitive potential on phospholipase A2, cyclooxygenase and lipoxygenase in the arachidonic acid pathway, and the subsequent reduction in prostaglandin and leukotriene generation, reveals the potential of phenolics as inflammation antagonists. The immunomodulative potential encompasses the capacity to interfere with proinflammatory cytokine synthesis and with the expression of the corresponding genes. A diet rich in antioxidants can result in prevention of inflammation-related pathologies. More investigations are necessary to establish the role of these antioxidants in therapy. The appropriate delivery system and the prooxidant effects exhibited at large doses, or in the presence of heavy metal cations should be regarded.

The Combination of Bioavailable Concentrations of Curcumin and Resveratrol Shapes Immune Responses While Retaining the Ability to Reduce Cancer Cell Survival

The polyphenols Curcumin (CUR) and Resveratrol (RES) are widely described for their antitumoral effects. However, their low bioavailability is a drawback for their use in therapy. The aim of this study was to explore whether CUR and RES, used at a bioavailable concentration, could modulate immune responses while retaining antitumor activity and to determine whether CUR and RES effects on the immune responses of peripheral blood mononuclear cells (PBMCs) and tumor growth inhibition could be improved by their combination. We demonstrate that the low-dose combination of CUR and RES reduced the survival of cancer cell lines but had no effect on the viability of PBMCs. Although following CUR + RES treatment T lymphocytes showed an enhanced activated state, RES counteracted the increased IFN-γ expression induced by CUR in T cells and the polyphenol combination increased IL-10 production by T regulatory cells. On the other hand, the combined treatment enhanced NK cell activity through the up- and downregulation of activating and inhibitory receptors and increased CD68 expression levels on monocytes/macrophages. Overall, our results indicate that the combination of CUR and RES at low doses differentially shapes immune cells while retaining antitumor activity, support the use of this polyphenol combinations in anticancer therapy and suggest its possible application as adjuvant for NK cell-based immunotherapies.

Natural Products and their Derivatives as Immune Check Point Inhibitors: Targeting Cytokine/Chemokine Signalling in Cancer

Cancer immunotherapy is the new generation and widely accepted form of tumour treatment. It is, however, associated with exclusive challenges which include organ-specific inflammation, and single-target strategies. Therefore, approaches that can enhance the efficiency of existing immunotherapies and expand their indications are required for the further development of immunotherapy. Natural products and medicines are stated to have this desired effect on cancer immunotherapy (adoptive immune-cells therapy, cancer vaccines, and immune-check point inhibitors). They refurbish the immunosuppressed tumour microenvironment, which is the primary location of interaction of tumour cells with the host immune system. Various immune cell subsets, via interaction with cytokine/chemokine receptors, are recruited into this microenvironment, and these subsets have roles in tumour progression and treatment responsiveness. This review summarises cytokine/chemokine signalling, types of cancer immunotherapy and the herbal medicine-derived natural products targeting cytokine/chemokines and immune checkpoints. These natural compounds possess immunomodulatory activities and exert their anti-tumour effect by either blocking the interaction or modulating the expression of the proteins linked with immune checkpoint signaling pathways. Some compounds also show a synergistic effect in combination with existing monoclonal antibody drugs to reverse the tumour microenvironment. Additionally, we have also reported some studies about the derivatives and formulations used to overcome the limitations of natural forms. This review can provide important insights for directing future research.

Resveratrol analogue, HS-1793, inhibits inflammatory mediator release from macrophages by interfering with the TLR4 mediated NF-κB activation

Resveratrol is known to have anti-inflammatory properties. However, high-dose resveratrol is required for optimal anti-inflammatory effects. HS-1793 is a derivative designed to be metabolically stable and more effective than resveratrol. We tested whether HS-1793 also has anti-inflammatory activity. HS-1793 effectively inhibited the mRNA and protein expression of lipopolysaccharide (LPS)-induced inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in macrophages. Therefore, the production of nitric oxide (NO) and prostaglandin E₂ (PGE₂) was significantly attenuated. In addition, HS-1793 completely suppressed the production of inflammatory cytokines enhanced by LPS treatment along with a decrease in Toll-like receptor 4 (TLR4) expression. At the same time, the expression of myeloid differentiation factor 88 (MyD88), IL-1 receptor-associated kinase 1 (IRAK1), and TNF receptor-associated factor 6 (TRAF6) signaling molecules and the nuclear translocation of nuclear factor kappa B (NF-κB)/p65 were also downregulated. We conclusively suggest that HS-1793 also exhibits anti-inflammatory properties by effectively inhibiting TLR4-mediated NF-κB activation.

Boosting immune system against cancer by resveratrol

Modulation of the immune system is a critical part of anticancer therapies including immunotherapy, chemotherapy, and radiotherapy. The aim of immunomodulation in cancer therapy is boosting immune system cells including CD8+ T lymphocytes and natural killer (NK) cells, as well as suppression of immunosuppressive responses by macrophages and regulatory T cells (Tregs). Usually, using single or dual modality can induce immune system responses against cancer. However, immunosuppressive responses attenuate antitumor immunity following cancer therapy. Using some agents to boost immune system's function against cancer can increase therapeutic efficiency of anticancer therapy. Resveratrol, as a natural agent, has shown ability to modulate the immune system to potentiate antitumor immunity. Resveratrol has been shown to induce the release of anticancer cytokines such as IFN-γ and TNF-α and also inhibits the release of TGF-β. It also can stimulate the polarization of CD4+ T cells and macrophages toward anticancer cells and reduce infiltration and polarization of immunosuppressive cells. Furthermore, resveratrol can sensitize cancer cells to the released dead signals by anticancer immune cells. This review explains how resveratrol can boost the immune system against cancer via modulation of immune cell responses within tumor.

Recent Advancements on Immunomodulatory Mechanisms of Resveratrol in Tumor Microenvironment

Immunomodulation of the tumor microenvironment is emerging as an important area of research for the treatment of cancer patients. Several synthetic and natural agents are being investigated for their ability to enhance the immunogenic responses of immune cells present in the tumor microenvironment to impede tumor cell growth and dissemination. Among them, resveratrol, a stilbenoid found in red grapes and many other natural sources, has been studied extensively. Importantly, resveratrol has been shown to possess activity against various human diseases, including cancer. Mechanistically, resveratrol has been shown to regulate an array of signaling pathways and processes involving oxidative stress, inflammation, apoptosis, and several anticancer effects. Furthermore, recent research suggests that resveratrol can regulate various cellular signaling events including immune cell regulation, cytokines/chemokines secretion, and the expression of several other immune-related genes. In this review, we have summarized recent findings on resveratrol’s effects on immune regulatory cells and associated signaling in various cancer types. Numerous immunomodulatory effects of resveratrol suggest it may be useful in combination with other cancer therapies including immunotherapy for effective cancer management.

Antioxidants for the Treatment of Breast Cancer: Are We There Yet?

Breast cancer is the most frequent cancer and the leading cause of cancer death in women. Oxidative stress and the generation of reactive oxygen species (ROS) have been related to cancer progression. Compared to their normal counterparts, tumor cells show higher ROS levels and tight regulation of REDOX homeostasis to maintain a low degree of oxidative stress. Traditionally antioxidants have been extensively investigated to counteract breast carcinogenesis and tumor progression as chemopreventive agents; however, there is growing evidence indicating their potential as adjuvants for the treatment of breast cancer. Aimed to elucidate whether antioxidants could be a reality in the management of breast cancer patients, this review focuses on the latest investigations regarding the ambivalent role of antioxidants in the development of breast cancer, with special attention to the results derived from clinical trials, as well as their potential use as plausible agents in combination therapy and their power to ameliorate the side effects attributed to standard therapeutics. Data retrieved herein suggest that antioxidants play an important role in breast cancer prevention and the improvement of therapeutic efficacy; nevertheless, appropriate patient stratification based on "redoxidomics" or tumor subtype is mandatory in order to define the dosage for future standardized and personalized treatments of patients.

Preparation of resveratrol dry suspension and its immunomodulatory and anti-inflammatory activity in mice

Context: Resveratrol is a natural polyphenol compound. It exhibits antitumor, immunostimulatory, and antiviral activities. However, poor water solubility and structural instability limit its administration and storage.Objective: A resveratrol dry suspension (RDS) was prepared and immunomodulatory effect in immunosuppressive mice induced by cyclophosphamide and anti-inflammatory activities in mice were evaluated.Materials and methods: The preparation of RDS was optimized by the orthogonal design method. To evaluate the immunomodulatory effects, SPF Kunming mice were divided into seven groups comprising of nine males and nine females for each group. The RDS supplemented group was administrated doses of 3.33, 1.67, and 0.83 g/kg/d. Then visceral index, lymphocyte proliferation, the ratio of CD3⁺ CD4⁺/CD3⁺ CD8⁺, and the contents of cytokines in serum were tested. To ameliorate effects of acetic acid induced capillary permeability, xylene-based ear oedema, and cotton pellet granuloma, RDS as anti-inflammatory agent was administered at doses of 1, 0.33, and 0.1 g/kg/d as compared to indomethacin (IM) provided as a positive control at 10 mg/kg.Results: RDS inhibited the degradation of resveratrol and enhanced the CD3⁺ CD4⁺/CD3⁺ CD8⁺ ratio, spleen index, IL-2 level, and splenic lymphocytes in immunosuppressive mice. RDS (0.1 g/kg/d) significantly inhibited the acetic acid-induced capillary permeability, and at doses of 0.33 and 1 g/kg/d repressed the ear swelling and granuloma formation in immunocompromised mice.Discussion and Conclusion: RDS is a stable, cheaper, and suitable preparation with potent immunoregulatory and anti-inflammatory activities. Keeping in view these remarkable properties, RDS could be an appropriate preparation for clinic use of resveratrol.

Targeting the tumor immune microenvironment with "nutraceuticals": From bench to clinical trials

The occurrence of immune effector cells in the tissue microenvironment during neoplastic progression is critical in determining tumor growth outcomes. On the other hand, tumors may also avoid immune system-mediated elimination by recruiting immunosuppressive leukocytes and soluble factors, which coordinate a tumor microenvironment that counteracts the efficiency of the antitumor immune response. Checkpoint inhibitor therapy results have indicated a way forward via activation of the immune system against cancer. Widespread evidence has shown that different compounds in foods, when administered as purified substances, can act as immunomodulators in humans and animals. Although there is no universally accepted definition of nutraceuticals, the term identifies a wide category of natural compounds that may impact health and disease statuses and includes purified substances from natural sources, plant extracts, dietary supplements, vitamins, phytonutrients, and various products with combinations of functional ingredients. In this review, we summarize the current knowledge on the immunomodulatory effects of nutraceuticals with a special focus on the cancer microenvironment, highlighting the conceptual benefits or drawbacks and subtle cell-specific effects of nutraceuticals for envisioning future therapies employing nutraceuticals as chemoadjuvants.

Natural products and their derivatives: Promising modulators of tumor immunotherapy

A wealth of evidence supports the role of tumor immunotherapy as a vital therapeutic option in cancer. In recent decades, accumulated studies have revealed the anticancer activities of natural products and their derivatives. Increasing interest has been driven toward finding novel potential modulators of tumor immunotherapy from natural products, a hot research topic worldwide. These works of research mainly focused on natural products, including polyphenols (e.g., curcumin, resveratrol), cardiotonic steroids (e.g., bufalin and digoxin), terpenoids (e.g., paclitaxel and artemisinins), and polysaccharide extracts (e.g., lentinan). Compelling data highlight that natural products have a promising future in tumor immunotherapy. Considering the importance and significance of this topic, we initially discussed the integrated research progress of natural products and their derivatives, including target T cells, macrophages, B cells, NKs, regulatory T cells, myeloid‐derived suppressor cells, inflammatory cytokines and chemokines, immunogenic cell death, and immune checkpoints. Furthermore, these natural compounds inactivate several key pathways, including NF‐κB, PI3K/Akt, MAPK, and JAK/STAT pathways. Here, we performed a deep generalization, analysis, and summarization of the previous achievements, recent progress, and the bottlenecks in the development of natural products as tumor immunotherapy. We expect this review to provide some insight for guiding future research.

The resveratrol analogue, HS‑1793, enhances the effects of radiation therapy through the induction of anti‑tumor immunity in mammary tumor growth

Radiotherapy can induce the infiltration of immune suppressive cells which are involved in promoting tumor progression and recurrence. A number of natural products with immunomodulating abilities have been gaining attention as complementary cancer treatments. This attention is partly due to therapeutic strategies which have proven to be ineffective as a result of tumor-induced immunosuppressive cells found in the tumor microenvironment. The present study investigated whether HS-1793, a resveratrol analogue, can enhance the anti-tumor effects by inhibiting lymphocyte damage and immune suppression by regulatory T cells (Tregs) and tumor-associated macrophages (TAMs), during radiation therapy. FM3A cells were used to determine the role of HS-1793 in the radiation-induced tumor immunity of murine breast cancer. HS-1793 treatment with radiation significantly increased lymphocyte proliferation with concanavalin A (Con A) stimulation and reduced the DNA damage of lymphocytes in irradiated tumor-bearing mice. The administration of HS-1793 also decreased the number of Tregs, and reduced interleukin (IL)-10 and transforming growth factor (TGF)-β secretion in irradiated tumor-bearing mice. In addition, HS-1793 treatment inhibited CD206⁺ TAM infiltration in tumor tissue when compared to the controls or irradiation alone. Mechanistically, HS-1793 suppressed tumor growth via the activation of effector T cells in irradiated mice. On the whole, the findings of the present study reveal that HS-1793 treatment improves the outcome of radiation therapy by enhancing antitumor immunity. Indeed, HS-1793 appears to be a good therapeutic candidate for use in combination with radiotherapy in breast cancer.

Influence of Resveratrol on the Immune Response

Resveratrol is the most well-known polyphenolic stilbenoid, present in grapes, mulberries, peanuts, rhubarb, and in several other plants. Resveratrol can play a beneficial role in the prevention and in the progression of chronic diseases related to inflammation such as diabetes, obesity, cardiovascular diseases, neurodegeneration, and cancers among other conditions. Moreover, resveratrol regulates immunity by interfering with immune cell regulation, proinflammatory cytokines’ synthesis, and gene expression. At the molecular level, it targets sirtuin, adenosine monophosphate kinase, nuclear factor-κB, inflammatory cytokines, anti-oxidant enzymes along with cellular processes such as gluconeogenesis, lipid metabolism, mitochondrial biogenesis, angiogenesis, and apoptosis. Resveratrol can suppress the toll-like receptor (TLR) and pro-inflammatory genes’ expression. The antioxidant activity of resveratrol and the ability to inhibit enzymes involved in the production of eicosanoids contribute to its anti-inflammation properties. The effects of this biologically active compound on the immune system are associated with widespread health benefits for different autoimmune and chronic inflammatory diseases. This review offers a systematic understanding of how resveratrol targets multiple inflammatory components and exerts immune-regulatory effects on immune cells.

Cancer Chemoprevention by Phytochemicals: Nature's Healing Touch

Phytochemicals are an important part of traditional medicine and have been investigated in detail for possible inclusion in modern medicine as well. These compounds often serve as the backbone for the synthesis of novel therapeutic agents. For many years, phytochemicals have demonstrated encouraging activity against various human cancer models in pre-clinical assays. Here, we discuss select phytochemicals—curcumin, epigallocatechin-3-gallate (EGCG), resveratrol, plumbagin and honokiol—in the context of their reported effects on the processes of inflammation and oxidative stress, which play a key role in tumorigenesis. We also discuss the emerging evidence on modulation of tumor microenvironment by these phytochemicals which can possibly define their cancer-specific action. Finally, we provide recent updates on how low bioavailability, a major concern with phytochemicals, is being circumvented and the general efficacy being improved, by synthesis of novel chemical analogs and nanoformulations.

CD4+CD25+ regulatory T cells in tumor immunity

Regulatory T cells (Tregs) are essential for maintaining peripheral tolerance, preventing autoimmune diseases and limiting chronic inflammatory diseases. Depletion of Tregs results in the onset of a variety of autoimmune diseases. Tregs are defined based on expression of CD4, CD25, and the transcription factor, FoxP3. It is now clear that three inhibitory cytokines, IL-10, IL-35 and TGF-β, are key mediators of Tregs function. Tregs have been shown to be important contributors to the development of immune tolerance toward tumors and play a critical role in the induction of tolerance to tumor associated antigens and suppression of anti-tumor immunity. Increasing researches support the existence of elevated numbers of regulatory T cells in cancer patients. Poor prognosis and decreased survival rates are closely correlated with higher Treg cell frequencies. Depletion of Tregs or blockade of their immune inhibitory role can enhance anti-tumor effects. Recent evidence suggests that Tregs may be responsible for the failure of host anti-tumor immunity by suppressing cytotoxic T-cells. In this review, we discuss cellular and molecular mechanisms in the differentiation and function of Tregs in tumor immunity.

Tumor associated macrophages provide the survival resistance of tumor cells to hypoxic microenvironmental condition through IL-6 receptor-mediated signals

Hypoxia and infiltration of tumor-associated macrophages (TAM) are intrinsic features of the tumor microenvironment. Tumor cells that remain viable in hypoxic conditions often possess an increased survival potential and tend to grow aggressively. TAM also respond to a variety of signals in the hypoxic tumor microenvironment and express a more M2-like phenotype. In this study, the established mouse tumor tissues showed a dense infiltration of CD206⁺ macrophages at the junctions between the normoxic and hypoxic regions and an increased IL-6 receptor (IL-6R) expression of tumor cells in the areas of CD206⁺ TAM accumulation, which indicates a role of M2 phenotype TAM in survival adaptation of tumor cells preparing for an impending hypoxic injury before changes in oxygen availability. Cocultured mouse FM3A or human MCF-7 tumor cells with tumor infiltrating macrophages isolated from mouse tumor tissues and M2-polarized macrophages generated from human THP-1 cells, respectively, showed significantly decreased rate of cell death in cultures exposed to hypoxia. The acquisition of survival resistance was attributed to increased IL-6 production by M2 TAM and increased expression of IL-6R in tumor cells in the coculture system. MCF-7 cells cocultured with M2 TAM showed activated JAK1/STAT3 and Raf/MEK/JNK pathways contributing to tyrosine and serine phophorylation of STAT3, respectively. However, only tyrosine phosphorylated STAT3 was detected in the nucleus, which induced upregulation of Bcl-2 and downregulation of Bax and Bak. Finally, knockdown of IL-6R by small interfering RNA significantly counteracted coculture-induced signals and completely abolished the survival resistance to hypoxic injury. Thus, we present evidence for the role of M2 phenotype TAM in IL-6 receptor-mediated signals, particularly tyrosine phosphorylation of STAT3, responsible for the prosurvival adaptation of tumor cells to hypoxia.

In Vitro Genotoxicity Assessment of a Novel Resveratrol Analogue, HS-1793

Resveratrol has received considerable attention as a polyphenol with various biological effects such as anti-inflammatory, anti-oxidant, anti-mutagenic, anti-carcinogenic, and cardioprotective properties. As part of the overall safety assessment of HS-1793, a novel resveratrol analogue free from the restriction of metabolic instability and the high dose requirement of resveratrol, we assessed genotoxicity in three in vitro assays: a bacterial mutation assay, a comet assay, and a chromosomal aberration assay. In the bacterial reverse mutation assay, HS-1793 did not increase revertant colony numbers in S. typhimurium strains (TA98, TA100, TA1535 and TA1537) or an E. coli strain (WP2 uvrA) regardless of metabolic activation. HS-1793 showed no evidence of genotoxic activity such as DNA damage on L5178Y Tk^+/− mouse lymphoma cells with or without the S9 mix in the in vitro comet assay. No statistically significant differences in the incidence of chromosomal aberrations following HS-1793 treatment was observed on Chinese hamster lung cells exposed with or without the S9 mix. These results provide additional evidence that HS-1793 is non-genotoxic at the dose tested in three standard tests and further supports the generally recognized as safe determination of HS-1793 during early drug development.

Interferon gamma induced by resveratrol analog, HS-1793, reverses the properties of tumor associated macrophages

Macrophages are capable of both inhibiting and promoting the growth and spread of cancers, depending on their activation state. Tumor-associated macrophages (TAM) are a kind of alternatively activated M2 macrophage, which may contribute to tumor progression. Following our previous study to evaluate the anti-tumor effect of a synthetic resveratrol analog HS-1793, the current study demonstrated that HS-1793 treatment significantly increased IFN-γ secreting cells in splenocytes and decreased CD206+ macrophage infiltration compared to CD68+ cells in the tumor site with a higher expression of IFN-γ. As these results suggested that IFN-γ increased locally at the tumor sites could modulate the status of TAM, we designed an in vitro model to study macrophage morphology and functions in relation to the tumor microenvironment. Human monocytic cell line THP-1 cells stimulated with phorbol-12-myristate-13-acetate (PMA) differentiated to macrophages with M2-like phenotypes. TAM-like properties of CD206(high), CD204(high), IL-10(high), TGF-β(high), IL-6(low), IL-12(low), VEGF(high), and MMP-9(high) and promotion of tumor cell invasion were more pronounced in M-2-polarized THP-1 macrophages generated by differentiating THP-1 cells with PMA and subsequently polarizing them with Th2 cytokines (IL-4/IL-13). Upon IFN-γ exposure, THP-1-derived TAM changed their phenotypes to the M-1-like morphology and intracellular granular pattern with an expression of an increased level of proinflammatory and immunostimulatory cytokines and a reduced level of immunosuppressive and tumor progressive mediators. These results explain the underlying mechanism of the anti-tumor activity of HS-1793. The elevated level of IFN-γ production after HS-1793 treatment evoked reprogramming of M-2 phenotype TAM, which efficiently countered the immunosuppressive and tumor progressive influences of TAM.

Protective activity of a novel resveratrol analogue, HS-1793, against DNA damage in 137Cs-irradiated CHO-K1 cells

Resveratrol has received considerable attention as a polyphenol with anti-oxidant, anti-carcinogenic, and anti-inflammatory effects. Radiation is an important component of therapy for a wide range of malignant conditions. However, it causes damage to normal cells and, hence, can result in adverse side effects. This study was conducted to examine whether HS-1793, a novel resveratrol analogue free from the restriction of metabolic instability and the high dose requirement of resveratrol, induces a protective effect against radiation-induced DNA damage. HS-1793 effectively scavenged free radicals and inhibited radiation-induced plasmid DNA strand breaks in an in vitro assay. HS-1793 significantly decreased reactive oxygen species and cellular DNA damage in 2 Gy-irradiated Chinese hamster ovary (CHO)-K1 cells. In addition, HS-1793 dose-dependently reduced the levels of phosphorylated H2AX in irradiated CHO-K1 cells. These results indicate that HS-1793 has chemical radioprotective activity. Glutathione levels and superoxide dismutase activity in irradiated CHO-K1 cells increased significantly following HS-1793 treatment. The enhanced biological anti-oxidant activity and chemical radioprotective activity of HS-1793 maintained survival of irradiated CHO-K1 cells in a clonogenic assay. Therefore, HS-1793 may be of value as a radioprotector to protect healthy tissue surrounding tumor cells during radiotherapy to obtain better tumor control with a higher dose.

HS-1793, a resveratrol analogue, induces cell cycle arrest and apoptotic cell death in human breast cancer cells

Resveratrol, a polyphenolic compound, is a naturally occurring phytochemical and is found in a variety of plants, including food such as grapes, berries and peanuts. It has gained much attention for its potential anticancer activity against various types of human cancer. However, the usefulness of resveratrol as a chemotherapeutic agent is limited by its photosensitivity and metabolic instability. In this study the effects of a synthetic analogue of resveratrol, HS-1793, on the proliferation and apoptotic cell death were investigated using MCF-7 (wild-type p53) and MDA-MB-231 (mutant p53) human breast cancer cells. HS-1793 inhibited cell growth and induced apoptotic cell death in a concentration-dependent manner. The induction of apoptosis was determined by morphological changes, cleavage of poly(ADP-ribose) poly-merase, alteration of Bax/Bcl-2 expression ratio and caspase activities. Flow cytometric analysis revealed that HS-1793 induced G2/M arrest in the cell cycle progression in both types of cells. Of note, HS-1793 induced p53/p21WAF1/CIP1-dependent apoptosis in MCF-7 cells, whereas it exhibited p53-independent apoptosis in MDA-MB-231 cells. Furthermore, HS-1793 showed more potent anticancer effects in several aspects compared to resveratrol in MCF-7 and MDA-MB-231 cells. Thus, these findings suggest that HS-1793 has potential as a candidate chemotherapeutic agent against human breast cancer.

Inhibition of breast cancer metastasis by resveratrol-mediated inactivation of tumor-evoked regulatory B cells

We reported previously that tumor-evoked regulatory B cells (tBregs) play an essential role in breast cancer lung metastasis by inducing TGF-β-dependent conversion of metastasis-promoting Foxp3(+) regulatory T cells (Tregs). In this article, we show that resveratrol (RSV), a plant-derived polyphenol, at low and noncytotoxic doses for immune cells, can efficiently inhibit lung metastasis in mice. The mechanism of this process is that RSV inactivates Stat3, preventing the generation and function of tBregs, including expression of TGF-β. As a result, it frees antitumor effector immune responses by disabling tBreg-induced conversion of Foxp3(+) Tregs. We propose that low doses of RSV may also benefit humans by controlling cancer escape-promoting tBregs/Tregs without nonspecific inactivation of effector immune cells.

A novel resveratrol analogue, HS-1793, inhibits hypoxia-induced HIF-1α and VEGF expression, and migration in human prostate cancer cells

In many studies, resveratrol has been shown to have a chemopreventive effect in various types of cancer cells. However, the biological activity of resveratrol is limited by its photosensitivity and metabolic instability. This study investigated the effects of a novel analogue of resveratrol, HS-1793, on the expression of HIF-1α and vascular endothelial growth factor (VEGF) in PC-3 human prostate cancer cells. Hypoxic condition induced HIF-1α protein level in PC-3 cells in a time-dependent manner, and treatment with HS-1793 markedly decreased HIF-1α expression levels. HS-1793 also inhibited VEGF level. Mechanistically, HS-1793 inhibited HIF-1α and VEGF expression through multiple mechanisms. Firstly, HS-1793 inhibited phosphorylation of PI3K and Akt in PC-3 cells. Furthermore, HS-1793 substantially induced HIF-1α protein degradation through the proteasome pathway. Finally, HS-1793 inhibited hypoxia-induced PC-3 cell migration. These data suggest that HS-1793 may inhibit human prostate cancer progression and angiogenesis by inhibiting the expression of HIF-1α and VEGF. Moreover, HS-1793 showed more potent effects than resveratrol on the cytotoxic effects on PC-3 cells. Taken together, these results implied that HS-1793, a novel analogue of resveratrol, may be a new potent chemopreventive agent against human prostate cancer cells.

Resveratrol Inhibits CD4+ T cell activation by enhancing the expression and activity of Sirt1

Resveratrol, a natural polyphenol compound, has broad effects on critical events, including inflammation, oxidation, cancer and aging. However, the function and molecular mechanisms of resveratrol on T cell activation are controversial. In the present study, we found that resveratrol significantly inhibits the activation and cytokine production of T cells in vitro and in vivo. Sirt1 expression was up-regulated in resveratrol-treated T cells. Once Sirt1 was down-regulated in the T cells, the resveratrol-induced inhibition of T cell activation noticeably diminished. The acetylation of c-Jun decreased and its translocation was impeded in the resveratrol-treated T cells. The incidence and severity of collagen-induced arthritis in the resveratrol-treated mice were considerably reduced.