Resveratrol modifies the expression of apoptotic regulatory proteins and sensitizes non-Hodgkin's lymphoma and multiple myeloma cell lines to paclitaxel-induced apoptosis

Modulation of the PI3K/Akt signaling pathway by resveratrol in cancer: molecular mechanisms and therapeutic opportunity

The phosphatidylinositol 3-kinase (PI3K)/Akt pathway is a critical intracellular signaling pathway that is pivotal in various cellular functions. It is in senescence, survival, and growth under normal physiological and pathological conditions, including neoplasms. Additionally, this pathway has been recognized as essential for the regulation of the cell cycle. Several previous studies have indicated that the PI3K/Akt signaling pathway can be influenced by various natural products, with resveratrol (3,4',5-trihydroxy-trans-stilbene) being a particularly important phytoalexin polyphenol in this context. This review explores the impact of the PI3K/Akt signaling pathway on the initiation and advancement of various cancerous conditions and the potential of resveratrol to target this signaling mechanism. The review begins by summarizing the anti-tumor capabilities of resveratrol and then emphasizes the significant role of the PI3K/Akt signaling pathway in the progression of multiple malignancies. Finally, we discuss the therapeutic effects of resveratrol on human neoplasms, from brain cancers to gastrointestinal malignancies, through regulation of this signaling cascade.

Resveratrol and Physical Activity: A Successful Combination for the Maintenance of Health and Wellbeing?

Physical exercise is an essential component of human health. In recent years, scientific research has focused on identifying natural compounds and formulating new supplements aimed at enhancing athletic performance, accelerating muscle recovery, and minimizing the damage caused by physical exertion. The use of antioxidants to counteract the formation of reactive oxygen species (ROS) following physical activity (PA) is already a widely adopted practice. Resveratrol (RES), a polyphenol belonging to the stilbene class, is well known for its potent antioxidant activity and anti-inflammatory effects primarily attributed to the activation of sirtuins. RES possesses multiple nutraceutical properties used for the prevention and treatment of inflammatory, cardiovascular, neoplastic, and infectious diseases, thus attracting attention to study its use in combination with physical exercise to promote well-being. Animal trials combining RES and PA have mainly reported improvements in muscle, energy, and cardiovascular functions. The data presented and discussed in this narrative review are from Pubmed, Scopus, and the Human Gene Database (search limited to 2011 to 2025 with the keywords RES, sirtuins, and physical activity altogether or in combination with each other). This review gathers several studies on RES focusing on its nutraceutical properties, epigenetic activities via sirtuins, and the potential benefits of combining RES with PA in maintaining health and well-being based on trials performed first in animals and later in humans. Human studies have been conducted on various populations, including active adults, sedentary individuals, patients with diseases, and elderly individuals. Some studies have confirmed the benefits of RES observed in animal experiments. However, in some cases, no substantial differences were found between RES supplementation and the control group. In conclusion, the benefits of RES on PA reported in the literature are still not fully evident, given the contrasting studies and the still limited number of trials, but both RES and PA are successful tools for the maintenance of health and wellbeing.

Phytocompounds and Nanoformulations for Anticancer Therapy: A Review

Cancer is a complex disease that affects millions of people and remains a major public health problem worldwide. Conventional cancer treatments, including surgery, chemotherapy, immunotherapy, and radiotherapy, have limited achievements and multiple drawbacks, among which are healthy tissue damage and multidrug-resistant phenotype onset. Increasing evidence shows that many plants' natural products, as well as their bioactive compounds, have promising anticancer activity and exhibit minimal toxicity compared to conventional anticancer drugs. However, their widespread use in cancer therapy is severely restricted by limitations in terms of their water solubility, absorption, lack of stability, bioavailability, and selective targeting. The use of nanoformulations for plants' natural product transportation and delivery could be helpful in overcoming these limitations, thus enhancing their therapeutic efficacy and providing the basis for improved anticancer treatment strategies. The present review is aimed at providing an update on some phytocompounds (curcumin, resveratrol, quercetin, and cannabinoids, among others) and their main nanoformulations showing antitumor activities, both in vitro and in vivo, against such different human cancer types as breast and colorectal cancer, lymphomas, malignant melanoma, glioblastoma multiforme, and osteosarcoma. The intracellular pathways underlying phytocompound anticancer activity and the main advantages of nanoformulation employment are also examined. Finally, this review critically analyzes the research gaps and limitations causing the limited success of phytocompounds' and nanoformulations' clinical translation.

Phytostilbenes in lymphoma: Focuses on the mechanistic and clinical prospects of resveratrol, pterostilbene, piceatannol, and pinosylvin

Lymphoma is a cancer affecting the lymphatic system that fights infections and diseases. In addition to surgery, radiotherapy, and chemotherapy, novel approaches have recently been investigated, such as phytostilbenes in treating lymphoma. Phytostilbenes are natural compounds present in various plants and have been shown to have different therapeutic effects, including anticancer properties. Resveratrol is a main phytostilbene with various derivates followed by pterostilbene and piceatannol. Studies have revealed that phytostilbenes can suppress the growth and proliferation of lymphoma cells by inducing apoptosis and inhibiting specific enzyme activity in cancer cell survival. The compounds also have antiinflammatory effects contributing to reducing lymphoma-associated inflammation. Additionally, phytostilbenes have been shown to increase the immune system's ability to fight cancer cells by activating immune cells (T-cells and natural killer cells). This review investigates the potential therapeutic effects of phytostilbenes, including resveratrol, pterostilbene, piceatannol, and pinosylvin, against lymphoma.

Determination of In Vitro and In Vivo Effects of Taxifolin and Epirubicin on Epithelial-Mesenchymal Transition in Mouse Breast Cancer Cells

Background: One of the most significant characteristics of cancer is epithelial-mesenchymal transition and research on the relationship between phenolic compounds and anticancer medications and epithelial-mesenchymal transition is widespread. Methods: In order to investigate the potential effects of Taxifolin on enhancing the effectiveness of Epirubicin in treating breast cancer, specifically in 4T1 cells and an allograft BALB/c model, the effects of Taxifolin and Epirubicin, both individually and in combination, were examined. Cell viability assays and cytotoxicity assays in 4T1 cells were performed. In addition, 4T1 cells were implanted into female BALB/c mice to conduct in vivo studies and evaluate the therapeutic efficacy of Taxifolin and Epirubicin alone or in combination. Tumor volumes and histological analysis were also assessed in mice. To further understand the mechanisms involved, we examined the messenger RNA and protein levels of epithelial-mesenchymal transition-related genes, as well as active Caspase-3/7 levels, using quantitative real-time polymerase chain reaction, western blot, and enzyme-linked immunosorbent assays, respectively. Results: In vitro results demonstrated that the coadministration of Taxifolin and Epirubicin reduced cell viability and cytotoxicity in 4T1 cell lines. In vivo, coadministration of Taxifolin and Epirubicin suppressed tumor growth in BALB/c mice with 4T1 breast cancer cells. Additionally, this combination treatment significantly increased the levels of active caspase-3/7 and downregulated the messenger RNA and protein levels of N-cadherin, β-catenin, vimentin, snail, and slug, but upregulated the E-cadherin gene. It significantly decreased the messenger RNA levels of the Zeb1 and Zeb2 genes. Conclusion: The in vitro and in vivo results of our study indicate that the concurrent use of Epirubicin with Taxifolin has supportive effects on breast cancer treatment.

Molecular mechanisms of resveratrol as chemo and radiosensitizer in cancer

One of the primary diseases that cause death worldwide is cancer. Cancer cells can be intrinsically resistant or acquire resistance to therapies and drugs used for cancer treatment through multiple mechanisms of action that favor cell survival and proliferation, becoming one of the leading causes of treatment failure against cancer. A promising strategy to overcome chemoresistance and radioresistance is the co-administration of anticancer agents and natural compounds with anticancer properties, such as the polyphenolic compound resveratrol (RSV). RSV has been reported to be able to sensitize cancer cells to chemotherapeutic agents and radiotherapy, promoting cancer cell death. This review describes the reported molecular mechanisms by which RSV sensitizes tumor cells to radiotherapy and chemotherapy treatment.

Targeting Glucose Metabolism to Enhance Immunotherapy: Emerging Evidence on Intermittent Fasting and Calorie Restriction Mimetics

There is growing interest in harnessing lifestyle and pharmaceutical interventions to boost immune function, reduce tumor growth, and improve cancer treatment efficacy while reducing treatment toxicity. Interventions targeting glucose metabolism are particularly promising, as they have the potential to directly inhibit tumor cell proliferation. However, because anti-tumor immune effector cells also rely on glycolysis to sustain their clonal expansion and function, it remains unclear whether glucose-modulating therapies will support or hinder anti-tumor immunity. In this perspective, we summarize a growing body of literature that evaluates the effects of intermittent fasting, calorie restriction mimetics, and anti-hyperglycemic agents on anti-tumor immunity and immunotherapy outcomes. Based on the limited data currently available, we contend that additional pre-clinical studies and clinical trials are warranted to address the effects of co-administration of anti-hyperglycemic agents or glucose-lowering lifestyle modifications on anti-tumor immunity and cancer treatment outcomes. We stress that there is currently insufficient evidence to provide recommendations regarding these interventions to cancer patients undergoing immunotherapy. However, if found to be safe and effective in clinical trials, interventions targeting glucose metabolism could act as low-cost combinatorial adjuvants for cancer patients receiving immune checkpoint blockade or other immunotherapies.

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.

Rationale for assessing the therapeutic potential of resveratrol in hematological malignancies

Promising results from pre-clinical studies on the naturally-occurring polyphenol resveratrol have generated considerable interest and somewhat excessive expectations regarding the therapeutic potential of this compound for treating or preventing various diseases, including cardiovascular and neurodegenerative disorders and cancer. Resveratrol has potent inhibitory activity in vitro against various tumor types, including cell lines derived from virtually all blood malignancies. Pharmacological studies have shown that resveratrol is safe for humans but has poor bioavailability, due to its extensive hepatic metabolism. Curiously, a substantial proportion of the orally administered resveratrol can reach the bone marrow compartment. Notably, various pathways dysregulated in blood cancers are known to be molecular targets of resveratrol, thus substantiating the potential utility of this agent in blood malignancies. In this review, we primarily focus on the scientific evidence that supports the potential utility of resveratrol for the management of select hematological malignancies. In addition, potential clinical trials with resveratrol are suggested.

The Effect of Resveratrol on Cell Viability in the Burkitt's Lymphoma Cell Line Ramos

Resveratrol is a polyphenolic natural compound produced by a variety of crops. Currently, resveratrol is considered a multi-target anti-cancer agent with pleiotropic activity, including the ability to prevent the proliferation of malignant cells by inhibiting angiogenesis and curtailing invasive and metastatic factors in many cancer models. However, the molecular mechanisms mediating resveratrol-specific effects on lymphoma cells remain unknown. To begin tackling this question, we treated the Burkitt's lymphoma cell line Ramos with resveratrol and assessed cell survival and gene expression. Our results suggest that resveratrol shows a significant anti-proliferative and pro-apoptotic activity on Ramos cells, inducing the DNA damage response, DNA repairing, and modulating the expression of several genes that regulate the apoptotic process and their proliferative activity.

Evaluation of Resveratrol in Cancer Patients and Experimental Models

Cancer is one of the top three causes of death in the United States. The treatment regimen for controlling cancer includes a number of approaches depending on the classification of the tumor. Treatment may include radiation, surgery, and cancer chemotherapy agents as well as other interventions. Natural products have been identified for centuries to contain active pharmacologic activity and have been a starting point for numerous drugs which are currently on the market. Resveratrol (RES) is a natural product generated in plants in response to environmental stress and growing conditions. RES has been recognized since 1997 to possess anticancer activity. This review discusses the dietary sources of RES and the relative amounts present in the various food sources. A few limited clinical studies have explored RES effects in patients with prostate and colorectal cancer and have suggested some beneficial results. Future studies need to expand the sample size for clinical examination of RES in order to provide a better profile for the potential benefit of RES in cancer patients. This review also describes the potential mechanisms of RES as an antioxidant and in alteration of cell signaling. Another aspect for the role of RES in cancer may be in the interaction with cancer chemotherapy agents. Cisplatin is a cancer chemotherapy agent used for the treatment of bladder, testicular, ovarian, and many other cancers. Cisplatin usage is associated with a high risk of nephrotoxicity. Experimental studies suggest that RES may reduce cisplatin renal toxicity. The proposed mechanisms of protection are reviewed.

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.

Activation of mutated TRPA1 ion channel by resveratrol in human prostate cancer associated fibroblasts (CAF)

Previous studies showed the effects of resveratrol (RES) on several cancer cells, including prostate cancer (PCa) cell apoptosis without taking into consideration the impact of the tumor microenvironment (TME). The TME is composed of cancer cells, endothelial cells, blood cells, and cancer-associated fibroblasts (CAF), the main source of growth factors. The latter cells might modify in the TME the impact of RES on tumor cells via secreted factors. Recent data clearly show the impact of CAF on cancer cells apoptosis resistance via secreted factors. However, the effects of RES on PCa CAF have not been studied so far. We have investigated here for the first time the effects of RES on the physiology of PCa CAF in the context of TME. Using a prostate cancer CAF cell line and primary cultures of CAF from prostate cancers, we show that RES activates the N-terminal mutated Transient Receptor Potential Ankyrin 1 (TRPA1) channel leading to an increase in intracellular calcium concentration and the expression and secretion of growth factors (HGF and VEGF) without inducing apoptosis in these cells. Interestingly, in the present work, we also show that when the prostate cancer cells were co-cultured with CAF, the RES-induced cancer cell apoptosis was reduced by 40%, an apoptosis reduction canceled in the presence of the TRPA1 channel inhibitors. The present work highlights CAF TRPA1 ion channels as a target for RES and the importance of the channel in the epithelial-stromal crosstalk in the TME leading to resistance to the RES-induced apoptosis.

South Asian Medicinal Compounds as Modulators of Resistance to Chemotherapy and Radiotherapy

Cancer is a hyperproliferative disorder that involves transformation, dysregulation of apoptosis, proliferation, invasion, angiogenesis and metastasis. During the last 30 years, extensive research has revealed much about the biology of cancer. Chemotherapy and radiotherapy are the mainstays of cancer treatment, particularly for patients who do not respond to surgical resection. However, cancer treatment with drugs or radiation is seriously limited by chemoresistance and radioresistance. Various approaches and strategies are employed to overcome resistance to chemotherapy and radiation treatment. Many plant-derived phytochemicals have been investigated for their chemo- and radio-sensitizing properties. The peoples of South Asian countries such as India, Pakistan, Sri Lanka, Nepal, Bangladesh and Bhutan have a large number of medicinal plants from which they produce various pharmacologically potent secondary metabolites. The medicinal properties of these compounds have been extensively investigated and many of them have been found to sensitize cancer cells to chemo- and radio-therapy. This review focuses on the role of South Asian medicinal compounds in chemo- and radio-sensitizing properties in drug- and radio-resistant cancer cells. Also discussed is the role of South Asian medicinal plants in protecting normal cells from radiation, which may be useful during radiotherapy of tumors to spare surrounding normal cells.

Neuroprotection of resveratrol against neurotoxicity induced by methamphetamine in mouse mesencephalic dopaminergic neurons

Resveratrol is originally extracted from huzhang, a Chinese herbal medicine. Recently, resveratrol has attracted a great of attention due to its antioxidant and antiapoptotic properties. Although the neuroprotection of resveratrol on neural damages in various models has been well characterized, little is known about the role of resveratrol in methamphetamine (MA) induced neurotoxicity in mesencephalic dopaminergic neurons. Dopaminergic neurons were isolated from midbrain of mouse embryos at embryonic day 15 and cultured in the presence of MA and resveratrol. Cell viability was examined by MTT assay and the apoptosis was assessed using Hoechst33342/PI double staining. To evaluate the Oxidative damage, ROS assay was performed. Moreover, the changes of time course of intracellular free calcium concentration ([Ca(2+) ]i) were analyzed with Fluo-3/AM tracing. The data showed that MA induced the neurotoxicity of cultured cells in a dose-dependent manner. Resveratrol significantly increased cellular viability and retarded cell apoptosis. Furthermore, resveratrol also attenuated MA induced ROS production and intracellular free calcium overload. Our results suggest that resveratrol protects dopaminergic neurons from MA-induced neuronal cytotoxicity, which, at least partly, is mediated by inhibition of [Ca(2+) ]i and oxidative stress. © 2015 BioFactors 41(4):252-260, 2015.

Concentration-dependent biphasic effects of resveratrol on human natural killer cells in vitro

Resveratrol (RES) is a polyphenol phytoalexin from plants, which has been reported to possess a variety of biological effects. The properties of RES on human natural killer (NK) cells were assessed in this study. Results showed that RES has concentration-dependent biphasic effects on NK cells. In high concentration (50 μM), RES can inhibit viability and promoted apoptosis of NK cells and human lymphoblastoid T (Jurkat) cells, which may affect the caspase signaling pathway. The Jurkat cells were more sensitive than NK cells on the RES caused cell death. However, when the concentration range reduced from 3.13 to 1.56 μM, RES showed the positive effects on NK cells by increasing the NK cells cytotoxicity via up-regulating the expression of NKG2D and IFN-γ (in mRNA and protein levels). These results indicated that one needs to pay more attention to the dosage and biphasic effects when RES was applied as antitumor drugs or health products.

Combinatorial chemotherapeutic efficacy in non-Hodgkin lymphoma can be predicted by a signaling model of CD20 pharmacodynamics

Combination chemotherapy represents the standard-of-care for non-Hodgkin lymphoma. However, the development of new therapeutic regimens is empirical and this approach cannot be used prospectively to identify novel or optimal drug combinations. Quantitative system pharmacodynamic models could promote the discovery and development of combination regimens based upon first principles. In this study, we developed a mathematical model that integrates temporal patterns of drug exposure, receptor occupancy, and signal transduction to predict the effects of the CD20 agonist rituximab in combination with rhApo2L/TNF-related apoptosis inducing ligand or fenretinide, a cytotoxic retinoid, upon growth kinetics in non-Hodgkin lymphoma xenografts. The model recapitulated major regulatory mechanisms, including target-mediated disposition of rituximab, modulation of proapoptotic intracellular signaling induced by CD20 occupancy, and the relative efficacy of death receptor isoforms. The multiscale model coupled tumor responses to individual anticancer agents with their mechanisms of action in vivo, and the changes in Bcl-xL and Fas induced by CD20 occupancy were linked to explain the synergy of these drugs. Tumor growth profiles predicted by the model agreed with cell and xenograft data, capturing the apparent pharmacologic synergy of these agents with fidelity. Together, our findings provide a mechanism-based platform for exploring new regimens with CD20 agonists.

Resveratrol triggers the pro-apoptotic endoplasmic reticulum stress response and represses pro-survival XBP1 signaling in human multiple myeloma cells

OBJECTIVE

Resveratrol, trans-3, 4', 5,-trihydroxystilbene, suppresses multiple myeloma (MM). The endoplasmic reticulum (ER) stress response component inositol-requiring enzyme 1α (IRE1α)/X-box binding protein 1 (XBP1) axis is essential for MM pathogenesis. We investigated the molecular action of resveratrol on IRE1α/XBP1 axis in human MM cells.

MATERIALS AND METHODS

Human MM cell lines ANBL-6, OPM2, and MM.1S were utilized to determine the molecular signaling events following treatment with resveratrol. The stimulation of IRE1α/XBP1 axis was analyzed by Western blot and reverse transcription polymerase chain reaction. The effect of resveratrol on the transcriptional activity of spliced XBP1 was assessed by luciferase assays. Chromatin immunoprecipitation was performed to determine the effects of resveratrol on the DNA binding activity of XBP1 in MM cells.

RESULTS

Resveratrol activated IRE1α as evidenced by XBP1 messenger RNA splicing and phosphorylation of both IRE1α and its downstream kinase c-Jun N-terminal kinase in MM cells. These responses were associated with resveratrol-induced cytotoxicity of MM cells. Resveratrol selectively suppressed the transcriptional activity of XBP1s while it stimulated gene expression of the molecules that are regulated by the non-IRE1/XBP1 axis of the ER stress response. Luciferase assays indicated that resveratrol suppressed the transcriptional activity of XBP1s through sirtuin 1, a downstream molecular target of resveratrol. Chromatin immunoprecipitation studies revealed that resveratrol decreased the DNA binding capacity of XBP1 and increased the enrichment of sirtuin 1 at the XBP1 binding region in the XBP1 promoter.

CONCLUSIONS

Resveratrol exerts its chemotherapeutic effect on human MM cells through mechanisms involving the impairment of the pro-survival XBP1 signaling and the activation of pro-apoptotic ER stress response.

Resveratrol regulates the expression of NHE-1 by repressing its promoter activity: critical involvement of intracellular H2O2 and caspases 3 and 6 in the absence of cell death

Na(+)/H(+) exchanger-1 (NHE-1) overexpression is associated with carcinogenesis and is an attractive target for intervention. We report that the chemopreventive agent resveratrol (RSV) downregulates NHE-1 in a caspase-dependent manner without inducing cell death. Resveratrol triggered early activation of caspase 3 and late activation of caspase 6, which were not inter-dependent. Whereas, caspase 3 activation appeared to be a direct effect of resveratrol, caspase 6 activation was mediated via intracellular hydrogen peroxide production and iron. Moreover, downregulation of NHE-1 expression was a function of resveratrol-induced repression of NHE-1 gene promoter activity. RNAi-mediated silencing of caspase 3 or 6 blocked the effect of resveratrol on NHE-1 expression, however the effect on NHE-1 promoter was observed at different phases of promoter repression with caspase 3 controlling the early phase (4-12 h) and caspase 6 regulating the late phase (12-24 h). Scavenging hydrogen peroxide or iron only reversed the late phase of resveratrol-induced NHE-1 promoter repression. Finally, an AP2 binding region within NHE-1 gene promoter was identified as the target of resveratrol. Collectively, these data could explain the anti-cancer activity of resveratrol in the light of the association of increased NHE-1 expression with carcinogenesis.

Anti-metastatic action of non-steroidal anti-inflammatory drugs

Epidemiological studies suggest that nonsteroidal anti-inflammatory drugs (NSAIDs) reduce the incidence and mortality of several types of human cancer. However, the molecular mechanisms by which NSAIDs exert their chemopreventive and anticancer effects are not fully understood. Cyclooxygenase 1 (COX-1) and COX-2 are the main targets for NSAIDs. Recent studies demonstrate that COX-2 is overexpressed in many human cancers and may promote tumorigenesis via: (1) stimulation of cancer cell proliferation; (2) increase of tumor angiogenesis; (3) prevention of cancer cell apoptosis; (4) modulation of immunoregulatory reactions; and (5) enhancement of tumor metastasis. NSAIDs may target the signaling molecules (from upstream activators to downstream effectors) involved in these mechanisms to attenuate the development and progression of cancer. In this review, we discuss the recent findings with regard to the mechanisms by which NSAIDs inhibit tumorigenesis and will specifically focus on the elucidation of NSAID-induced inhibition of tumor metastasis.

Resveratrol engages selective apoptotic signals in gastric adenocarcinoma cells

AIM: To investigate the intracellular apoptotic signals engaged by resveratrol in three gastric adenocarcinoma cancer cell lines, two of which (AGS and SNU-1) express p53 and one (KATO-III) with deleted p53.

METHODS: Nuclear fragmentation was used to quanti-tate apoptotic cells; caspase activity was determined by photometric detection of cleaved substrates; formation of oxidized cytochrome C was used to measure cytochrome C activity, and Western blot analysis was used to determine protein expression.

RESULTS: Gastric cancer cells, irrespective of their p53 status, responded to resveratrol with fragmentation of DNA and cleavage of nuclear lamins A and B and PARP. Resveratrol, however, has no effect on mitochondria-associated apoptotic proteins Bcl-2, Bcl-xl, Bax, Bid or Smac/Diablo, and did not promote sub-cellular redistribution of cytochrome C, indicating that resveratrol-induced apoptosis of gastric carcinoma cells does not require breakdown of mitochondrial membrane integrity. Resveratrol up-regulated p53 protein in SNU-1 and AGS cells but there was a difference in response of intracellular apoptotic signals between these cell lines. SNU-1 cells responded to resveratrol treatment with down-regulation of survivin, whereas in AGS and KATO-III cells resveratrol stimulated caspase 3 and cytochrome C oxidase activities.

CONCLUSION: These findings indicate that even within a specific cancer the intracellular apoptotic signals engaged by resveratrol are cell type dependent and suggest that such differences may be related to differentiation or lack of differentiation of these cells.

Using chemopreventive agents to enhance the efficacy of cancer therapy

Emerging evidence suggests that cancer preventative agents might be combined with chemotherapy or radiotherapy for the more effective treatment of cancer. Recent studies suggest that genistein and other dietary compounds that prevent cancer may enhance the efficacy of cancer therapeutics by modifying the activity of key cell proliferation and survival pathways, such as those controlled by Akt, nuclear factor-kappaB, and cyclooxygenase-2. In this article, we summarize the findings of recent investigations of chemopreventive agents in combination with cancer treatment regimens.

Resveratrol Inhibits Myeloma Cell Growth, Prevents Osteoclast Formation, and Promotes Osteoblast Differentiation

Multiple myeloma is characterized by the accumulation of clonal malignant plasma cells in the bone marrow, which stimulates bone destruction by osteoclasts and reduces bone formation by osteoblasts. In turn, the changed bone microenvironment sustains survival of myeloma cells. Therefore, a challenge for treating multiple myeloma is discovering drugs targeting not only myeloma cells but also osteoclasts and osteoblasts. Because resveratrol (trans-3,4',5-trihydroxystilbene) is reported to display antitumor activities on a variety of human cancer cells, we investigated the effects of this natural compound on myeloma and bone cells. We found that resveratrol reduces dose-dependently the growth of myeloma cell lines (RPMI 8226 and OPM-2) by a mechanism involving cell apoptosis. In cultures of human primary monocytes, resveratrol inhibits dose-dependently receptor activator of nuclear factor-kappaB (NF-kappaB) ligand-induced formation of tartrate-resistant acid phosphatase (TRACP)-positive multinucleated cells, TRACP activity in the medium, up-regulation of cathepsin K gene expression, and bone resorption. These inhibitions are associated with a down-regulation of RANK expression at both mRNA and cell surface protein levels and a decrease of NFATc1 stimulation and NF-kappaB nuclear translocation, whereas the gene expression of c-fms, CD14, and CD11a is up-regulated. Finally, resveratrol promotes dose-dependently the expression of osteoblast markers like osteocalcin and osteopontin in human bone marrow mesenchymal stem cells (hMSC-TERT) and stimulates their response to 1,25(OH)2 vitamin D3 [1,25(OH)2D3]. Moreover, resveratrol up-regulates dose-dependently the expression of 1,25(OH)2D3 nuclear receptor. Taken together, these results suggest that resveratrol or its derivatives deserve attention as potential drugs for treating multiple myeloma.

Rituximab (Chimeric Anti-CD20 Monoclonal Antibody) Inhibits the Constitutive Nuclear Factor-κB Signaling Pathway in Non-Hodgkin's Lymphoma B-Cell Lines: Role in Sensitization to Chemotherapeutic Drug-induced Apoptosis

The chimeric anti-CD20 antibody rituximab (Rituxan, IDEC-C2B8) is widely used in the clinical treatment of patients with non-Hodgkin's lymphoma (NHL). Rituximab sensitizes NHL B-cell lines to drug-induced apoptosis via down-regulation of Bcl-xL expression. We hypothesized that the mechanism by which rituximab down-regulates Bcl-xL may be, in part, due to inhibition of constitutive nuclear factor-κB (NF-κB) activity that regulates Bcl-xL expression. This hypothesis was tested in CD20+ drug-resistant Ramos (Bcl-2−/Bcl-xL+) and Daudi (Bcl-2+/Bcl-xL+) cell lines. Rituximab decreased the phosphorylation of NF-κB-inducing kinase, IκB kinase, and IκB-α, diminished IKK kinase activity, and decreased NF-κB DNA binding activity. These events occurred with similar kinetics and were observed 3 to 6 hours post-rituximab treatment. Rituximab significantly up-regulated Raf-1 kinase inhibitor protein expression, thus interrupting the NF-κB signaling pathway concomitant with Bcl-xL and Bfl-1/A1 down-regulation. The role of NF-κB in the regulation of Bcl-xL transcription was shown using promoter reporter assays in which deletion of the two-tandem NF-κB binding sites in the upstream promoter region significantly reduced the luciferase activity. This was further corroborated by using IκB superrepressor cells and by NF-κB–specific inhibitors. The direct role of Bcl-xL in drug resistance was assessed by using Bcl-xL–overexpressing cells, which exhibited higher drug resistance that was partially reversed by rituximab. Rituximab-mediated inhibition of the NF-κB signaling pathway and chemosensitization was corroborated by the use of specific inhibitors. These findings reveal a novel pathway mediated by rituximab through Raf-1 kinase inhibitor protein induction that negatively regulates the constitutive NF-κB pathway and chemosensitization of the NHL B-cells.

Inhibition of the Raf-MEK1/2-ERK1/2 signaling pathway, Bcl-xL down-regulation, and chemosensitization of non-Hodgkin's lymphoma B cells by Rituximab

Rituximab (Rituxan, IDEC-C2B8) has been shown to sensitize non-Hodgkin's lymphoma (NHL) cell lines to chemotherapeutic drug-induced apoptosis. Rituximab treatment of Bcl-2-deficient Ramos cells and Bcl-2-expressing Daudi cells selectively decreases Bcl-(xL) expression and sensitizes the cells to paclitaxel-induced apoptosis. This study delineates the signaling pathway involved in rituximab-mediated Bcl-(xL) down-regulation in Ramos and Daudi NHL B cells. We hypothesized that rituximab may interfere with the extracellular signal-regulated kinase (ERK) 1/2 pathway, leading to decreased Bcl-(xL) expression. Rituximab (20 microg/mL) inhibited the kinase activity of mitogen-activated protein kinase kinase (MEK) 1/2 and reduced the phosphorylation of the components of the ERK1/2 pathway (Raf-1, MEK1/2, and ERK1/2) and decreased activator protein-1 DNA binding activity and Bcl-(xL) gene expression. These events occurred with similar kinetics and were observed 3 to 6 hours after rituximab treatment. Rituximab-mediated effects were corroborated by using specific inhibitors of the ERK1/2 pathway, which also reduced Bcl-(xL) levels and sensitized the NHL B cells to paclitaxel-induced apoptosis. Previous findings implicated a negative regulatory role of the Raf-1 kinase inhibitor protein (RKIP) on the ERK1/2 pathway. Rituximab treatment of NHL B cells significantly up-regulated RKIP expression, thus interrupting the ERK1/2 signaling pathway through the physical association between Raf-1 and RKIP, which was concomitant with Bcl-(xL) down-regulation. These novel findings reveal a signaling pathway triggered by rituximab, whereby rituximab-mediated up-regulation of RKIP adversely regulates the activity of the ERK1/2 pathway, Bcl-(xL) expression, and subsequent chemosensitization of drug-refractory NHL B cells. The significance of these findings is discussed.