Old wine in a new bottle: the Warburg effect and anticancer mechanisms of resveratrol.

Resveratrol found in fruits, vegetables and beverages such as red wine, has been extensively evaluated for its anticardiovascular disease and cancer preventive effects. Even though studies have demonstrated its anti-tumor effects, there is still no clear explanation for cancer cell selective mechanisms of action of resveratrol. Initial investigations were focused on its anti-oxidant and cytoprotective mechanism of action, yet, a large number of studies have demonstrated that resveratrol can behave either as anti-oxidant or pro-oxidant depending on the selective microenvironment. What makes resveratrol a protective agent in normal cells and a radical generator possessing cytotoxic activity against cancer cells is a widely debated topic. There must be certain conditions found in tumors that allow resveratrol to become a pro-oxidant that clearly differs from that found in normal cells. Results of studies from our group have established that many different dietary agents can mobilize intracellular copper ions and in the process, generate reactive oxygen species through Fenton type reactions leading to oxidative DNA breakage and consequently, cell death. More significantly, we demonstrated that such pro-oxidant-induced DNA damage and apoptotic activity are enhanced in low pH environments; characteristically observed in tumors due to preferential dependence on glycolysis or the "Warburg effect". This review discusses the recent advancements in understanding the pro-oxidant anti-cancer behavior of resveratrol as a dietary chemopreventive agent, explained in the light of the Warburg effect.

Resveratrol-induced apoptosis is enhanced in low pH environments associated with cancer.

Many critical factors such as hypoxia, nutrient deficiency, activation of glycolytic pathway/Warburg effect contribute to the observed low pH in tumors compared to normal tissue. Studies suggest that such tumor specific acidic environment can be exploited for the development of therapeutic strategies against cancer. Independent observations show reduction in pH of mammalian cells undergoing internucleosomal DNA fragmentation and apoptosis. As such, our group has extensively demonstrated that anticancer mechanisms of different plant polyphenols involve mobilization of endogenous copper and consequent internucleosomal DNA breakage. Copper is redox active metal, an essential component of chromatin and is sensitive to subtle pH changes in its microenvironment. Here we explored whether, acidic pH promotes growth inhibition, apoptosis, and DNA damaging capacity of chemopreventive agent resveratrol. Our results reveal that growth inhibition and internucleosomal DNA fragmentation induced apoptosis in Capan-2 and Panc-28 pancreatic cancer cell lines (and not in normal HPDE cells) by resveratrol is enhanced at lower pH. Using comet assay, we further demonstrate that DNA breakage by resveratrol is enhanced with acidification. Membrane permeable copper specific chelator neocuproine (and not iron chelator orthophenanthroline) abrogated growth inhibition and apoptosis by resveratrol. Western blot results show enhanced activation of DNA laddering marker H2.aX by resveratrol at acidic pH that was reversed by neocuproine and not by orthophenanthroline. Our findings provide irrevocable proof that low pH environment can be turned into tumor weakness and assist in eradication of cancer cells by resveratrol.

Aberrant epigenetic grooming of miRNAs in pancreatic cancer: a systems biology perspective.

Pancreatic cancer (PC) is a complex disease harboring a myriad of genetic and epigenetic changes. The dismal survival of patients diagnosed with PC is in part due to de novo and acquired resistance to conventional therapeutics, resulting from deregulated signaling including aberrant expression of small nc miRNAs. Emerging research in this area has lead to the identification and characterization of deregulated miRNAs, which have generated a renewed interest and hope in that novel targeting of miRNAs may lead to a better clinical outcome for patients diagnosed with PC. However, recent evidence suggests that miRNAs are also under a highly coordinated system of epigenetic regulation emphasizing the fact that the design of miRNAs as targeted therapy may not be as simple as originally anticipated. For a successful miRNA-based therapeutic regimen, a holistic integrated approach may be required to take into account because of these emerging epigenetic regulatory mechanisms. In this article, we will discuss miRNA epigenetics, it's significance in PC and the use of a systems science to identify these aberrant epigenetically groomed miRNAs, and we believe that such knowledge would likely benefit further research to realize the dream of miRNA-based targeted therapy for human malignancies.

Network modeling of MDM2 inhibitor-oxaliplatin combination reveals biological synergy in wt-p53 solid tumors.

Earlier we had shown that the MDM2 inhibitor (MI-219) belonging to the spiro-oxindole family can synergistically enhance the efficacy of platinum chemotherapeutics leading to 50% tumor free survival in a genetically complex pancreatic ductaladenocarcinoma (PDAC) xenograft model. In this report, we have taken a systems and network modeling approach in order to understand central mechanisms behind MI219-oxaliplatin synergy with validation in PDAC, colon and breast cancer cell lines. Microarray profiling of drug treatments (MI-219, oxaliplatin or their combination) in capan-2 cells reveal a similar unique set of gene alterations that is duplicated in other solid tumor cells. As single agent, MI-219 or oxaliplatin induced alterations in 48 and 761 genes respectively. The combination treatment resulted in 767 gene alterations with emergence of 286 synergy unique genes. Ingenuity network modeling of combination and synergy unique genes showed the crucial role of five key local networks CREB, CARF, EGR1, NF-kB and E-Cadherin. Compared to single agents the combination treatment super induced p53 and p21 confirming functional synergy. Further, the network signatures were validated at the protein level in all three cell lines. Individually silencing central nodes in these five hubsinterfered with MI-219-oxaliplatin activity confirming their critical role in aiding p53 mediated apoptotic response. We anticipate that our MI219-oxaliplatin network blueprints can be clinically translated in the rationale design and application of this unique therapeutic combination in a genetically pre-defined subset of patients.

Network perspectives on HDM2 inhibitor chemotherapy combinations.

The discovery of small molecule inhibitors of HDM2-p53 interaction is considered one of the most significant therapeutic developments in the area p53 research. Intensive work on different classes of HDM2 inhibitors has proven their therapeutic utility as activators of p53 in multiple tumor models. Many laboratories have shown that HDM2 inhibitors can synergize with chemotherapeutic agents resulting in enhanced efficacy through both p53-dependent and independent mechanisms. In our hands HDM2 inhibitor and platinum drug combination showed remarkable antitumor activity that led tumor free survival in one of the most resistant and complex pancreatic xenograft models. Although antitumor efficacy of such combinations has been studied in detail, not much is known on the molecular mechanisms governing this synergy. This is partly due to complexity of multiple pathways modulated by p53 and HDM2. We are of the view that in order to decode this complexity, an integrated approach is needed that considers both HDM2 and p53 as components of a network and not in isolation. This review highlights recent advancements in our understanding of HDM2 inhibitor combination therapy based on network modeling and systems biology driven science. Our recent findings support such a network view as integrated gene expression profiling and pathway network modeling on MI-219-oxaliplatin treated cells revealed activation of multiple and closely knit biological networks. We anticipate that in the near future such network-centric approaches will benefit clinical development of HDM2 inhibitors for genetically predefined subsets of cancer patients and this will be a step towards personalized medicine.

Intracellular free zinc up-regulates IFN-γ and T-bet essential for Th1 differentiation in Con-A stimulated HUT-78 cells.

Zinc deficiency impairs cellular immunity. Up-regulation of mRNA levels of IFN-γ, IL-12Rß2, and T-bet are essential for Th(1) differentiation. We hypothesized that zinc increases Th(1) differentiation via up-regulation of IFN-γ and T-bet expression. To test this hypothesis, we used zinc-deficient and zinc-sufficient HUT-78 cells (a Th(0) cell line) under different condition of stimulation in this study. We also used TPEN, a zinc-specific chelator, to decrease the bioavailability of zinc in the cells. We measured intracellular free zinc, cytokines, and the mRNAs of T-bet, IFN-γ, and IL-12Rß2. In this study, we show that in zinc-sufficient HUT-78 cells, mRNA levels of IFN-γ, IL-12Rß2, and T-bet in PMA/PHA-stimulated cells were increased in comparison to zinc-deficient cells. Although intracellular free zinc was increased slightly in PMA/PHA-stimulated cells, Con-A-stimulated cells in 5µM zinc medium showed a greater sustained increase in intracellular free zinc in comparison to cells incubated in 1µM zinc. The cells pre-incubated with TPEN showed decreased mRNA levels of IFN-γ and T-bet mRNAs in comparison to cells without TPEN incubation. We conclude that stimulation of cells by Con-A via TCR, release intracellular free zinc which functions as a signal molecule for generation of IFN-γ and T-bet, and IL-12Rß2 mRNAs required for Th(1) cell differentiation. These results suggest that zinc increase Th(1) cell differentiation by up-regulation of IFN-γ and T-bet, and IL-12Rbß2 mRNAs.

Zinc-suppressed inflammatory cytokines by induction of A20-mediated inhibition of nuclear factor-κB.

OBJECTIVE: Chronic generation of inflammatory cytokines and reactive oxygen species are implicated in atherosclerosis, aging, cancers, and other chronic diseases. We hypothesized that zinc induces A20 in premonocytic, endothelial, and cancer cells, and A20 binds to tumor necrosis factor (TNF)-receptor associated factor, and inhibits Iκ kinase-α (IKK-α)/nuclear factor-κB (NF-κB), resulting in downregulation of TNF-α and interleukin-1ß (IL-1ß). METHODS: To test this hypothesis, we used HL-60, human umbilical vein endothelial cells, and SW480 cell lines under zinc-deficient and zinc-sufficient conditions in this study. We measured oxidative stress markers, inflammatory cytokines, A20 protein and mRNA, A20-FRAF-1 complex, and IKK-α/NF-κB signaling in stimulated zinc-deficient and zinc sufficient cells. We also conducted antisense A20 and siRNA studies to investigate the regulatory role of zinc in TNF-α and IL-1ß via A20. RESULTS: We found that zinc increased A20 and A20-tumor necrosis factor-receptor associated factor-1 complex, decreased the IKK-α/NF-κB signaling pathway, oxidative stress markers, and inflammatory cytokines in these cells compared with zinc-deficient cells. We confirmed that zinc-induced A20 contributes to downregulation of TNF-α and IL-1ß by antisense and short interfering RNA A20 studies. CONCLUSION: Our studies suggest that zinc suppresses generation of NF-κB-regulated inflammatory cytokines by induction of A20.

Zinc decreases C-reactive protein, lipid peroxidation, and inflammatory cytokines in elderly subjects: a potential implication of zinc as an atheroprotective agent.

BACKGROUND: Chronic inflammation and oxidative stress are common risk factors for atherosclerosis. Zinc is an essential micronutrient that can function as an antiinflammatory and antioxidative agent, and as such, it may have atheroprotective properties. OBJECTIVE: We hypothesized that zinc down-regulates the production of atherosclerosis-related cytokines/molecules in humans. DESIGN: To examine these effects, we conducted a randomized, double-blinded, placebo trial of zinc supplementation in elderly subjects. We recruited 40 healthy elderly subjects (aged 56-83 y) and randomly assigned them to 2 groups. One group was given an oral dose of 45 mg zinc/d as a gluconate for 6 mo. The other group was given a placebo. Cell culture models were conducted to study the mechanism of zinc as an atheroprotective agent. RESULTS: After 6 mo of supplementation, the intake of zinc, compared with intake of placebo, increased the concentrations of plasma zinc and decreased the concentrations of plasma high-sensitivity C-reactive protein (hsCRP), interleukin (IL)-6, macrophage chemoattractant protein 1 (MCP-1), vascular cell adhesion molecule 1 (VCAM-1), secretory phospholipase A2, and malondialdehyde and hydroxyalkenals (MDA+HAE) in elderly subjects. Regression analysis showed that changes in concentrations of plasma zinc were inversely associated with changes in concentrations of plasma hsCRP, MCP-1, VCAM-1, and MDA+HAE after 6 mo of supplementation. In cell culture studies, we showed that zinc decreased the generation of tumor necrosis factor-alpha, IL-1beta, VCAM-1, and MDA+HAE and the activation of nuclear transcription factor kappaB and increased antiinflammatory proteins A20 and peroxisome proliferator-activated receptor-alpha in human monocytic leukemia THP-1 cells and human aortic endothelial cells compared with zinc-deficient cells. CONCLUSION: These findings suggest that zinc may have a protective effect in atherosclerosis because of its antiinflammatory and antioxidant functions.

Dietary zinc and prostate cancer in the TRAMP mouse model.

Circumstantial evidence indicates that zinc may have an important role in the prostate. Total zinc levels in the prostate are 10 times higher than in other soft tissues. Zinc concentrations in prostate epithethial cancer cells are decreased significantly. Zinc supplementation for prevention and treatment of prostate cancer in humans has yielded controversial results. No studies have been reported in animal models to show the effect of zinc supplementation on prevention of prostate cancer, thus far. In this study, we have examined the effect of zinc supplementation on development of prostate cancer in a TRAMP mouse model. Results from our study indicate that dietary zinc plays an important role in prostate carcinogenesis. Tumor weights were significantly higher when the dietary zinc intake was either deficient or high in comparison to normal zinc intake level, suggesting that an optimal dietary zinc intake may play a protective role against prostate cancer. Further, our studies also showed decreased insulin-like growth factor (IGF)-1 and IGF-1/IGF binding protein-3 ratio in normal zinc-supplemented animals, suggesting that zinc may modulate IGF-1 metabolism in relation to carcinogenesis. We conclude that optimal prostate zinc concentration has a protective role against cancer.

Zinc in cancer prevention.

Essentiality of zinc for humans was discovered 45 yr ago. Deficiency of zinc is prevalent world wide in developing countries and may affect nearly 2 billion subjects. The major manifestations of zinc deficiency include growth retardation, hypogonadism in males, cell-mediated immune dysfunctions, and cognitive impairment. Zinc not only improves cell mediated immune functions but also functions as an antioxidant and anti-inflammatory agent. Oxidative stress and chronic inflammation have been implicated in development of many cancers. In patients with head and neck cancer, we have shown that nearly 65% of these patients were zinc deficient based on their cellular zinc concentrations. Natural killer (NK) cell activity and IL-2 generation were also affected adversely. Th2 cytokines were not affected. In our patients, zinc status was a better indicator of tumor burden and stage of disease in comparison to the overall nutritional status. Zinc status also correlated with number of hospital admissions and incidences of infections. NF-kappa B is constitutively activated in many cancer cells, and this results in activation of antiapoptotic genes, VEGF, cyclin DI, EGFR, MMP-9 and inflammatory cytokines. Zinc inhibits NF-kappa B via induction of A-20. Thus, zinc supplementation should have beneficial effects on cancer by decreasing angiogenesis and induction of inflammatory cytokines while increasing apoptosis in cancer cells. Based on the above, we recommend further studies and propose that zinc should be utilized in the management and chemoprevention of cancer.

Zinc deficiency in Mexican American children: influence of zinc and other micronutrients on T cells, cytokines, and antiinflammatory plasma proteins.

BACKGROUND: The Third National Health and Nutrition Examination Survey suggested some Mexican American children are at risk of zinc deficiency. OBJECTIVE: We measured the effects of zinc and micronutrients or of micronutrients alone on indexes of cell-mediated immunity and antiinflammatory plasma proteins. DESIGN: Subjects (n = 54) aged 6-7 y were randomly assigned and treated in double-blind fashion in equal numbers with 20 mg Zn (as sulfate) and micronutrients or with micronutrients alone 5 d/wk for 10 wk. RESULTS: Before treatment the mean +/- SD plasma zinc was 14.9 +/- 1.7 micromol/dL and the range was within the reference; hair zinc was 1.78 +/- 0.52 micromol/g and 41.6% were < or =1.68 micromol/g; serum ferritin was 25.7 +/- 18.6 microg/L and 50.0% were < or =20 microg/L. The zinc and micronutrients treatment increased the lymphocyte ratios of CD4(+) to CD8(+) and of CD4(+)CD45RA(+) to CD4(+)CD45RO(+), increased the ex vivo generation of interleukin-2 (IL-2) and interferon-gamma (IFN-gamma), decreased the generation of interleukin-10 (IL-10), and increased plasma interleukin-1 receptor antagonist (sIL-1ra) and soluble tumor necrosis factor receptor 1 (sTNF-R1). Micronutrients alone increased the ratio of CD4(+) to CD8(+) but not of CD4(+)CD45RA(+) to CD4(+)CD45RO(+), increased IFN-gamma but had no effect on IL-2 or IL-10, and increased sIL-1ra but not sTNF-R1. Efficacy of zinc and micronutrients was greater than micronutrients alone for all indexes except the ratio of CD4(+) to CD8(+), which was affected similarly. CONCLUSIONS: Before treatment, concentrations of hair zinc in 41.6% of subjects and serum ferritin in 50% were consistent with the presence of zinc deficiency. The greater efficacy of the zinc and micronutrients treatment compared with micronutrients alone supports this interpretation.

Zinc supplementation decreases oxidative stress, incidence of infection, and generation of inflammatory cytokines in sickle cell disease patients.

Zinc deficiency is common in adult sickle-cell disease (SCD) patients. We previously demonstrated that zinc supplementation to adult SCD patients decreased the incidences of infections and hospital admissions. We hypothesize that zinc supplementation improves T-helper cell function and decreases vascular endothelial cell activation, oxidative stress, and nuclear factor-kappa B (NF-kappaB)-DNA binding in mononuclear cells (MNCs) in SCD patients. To test this hypothesis, 36 SCD patients were recruited and randomly divided into 2 groups. One group (n = 18) received 25-mg zinc orally thrice a day for 3 months. The other group (n = 18) received placebo. The results indicate that the zinc-supplemented group had decreased incidence of infections compared with the placebo group. After zinc supplementation, red blood cell, hemoglobin (Hb), hematocrit, (Hct), plasma zinc, and antioxidant power increased; plasma nitrite and nitrate (NOx), lipid peroxidation products, DNA oxidation products, and soluble vascular cell adhesion molecule-1 decreased in the zinc-supplemented group, compared with the placebo group. Zinc-supplemented patients exhibited significant decreases in lipopolysaccharide-induced tumor necrosis factor-alpha (TNF-alpha) and IL-1beta mRNAs, and TNF-induced nuclear factor of kappaB-DNA binding in MNCs, compared with the placebo group. Ex vivo addition of zinc to MNCs isolated from the placebo subjects decreased TNF-alpha and IL-1beta mRNAs. Zinc supplementation also increased relative levels of IL-2 and IL-2Ralpha mRNAs in phytohemagglutinin-p-stimulated MNCs. These results suggest that zinc supplementation may be beneficial to SCD patients.

Duration and severity of symptoms and levels of plasma interleukin-1 receptor antagonist, soluble tumor necrosis factor receptor, and adhesion molecules in patients with common cold treated with zinc acetate.

BACKGROUND: Zinc lozenges have been used for treatment of the common cold; however, the results remain controversial. METHODS: Fifty ambulatory volunteers were recruited within 24 h of developing symptoms of the common cold for a randomized, double-blind, placebo-controlled trial of zinc. Participants took 1 lozenge containing 13.3 mg of zinc (as zinc acetate) or placebo every 2-3 h while awake. The subjective scores for common cold symptoms were recorded daily. Plasma zinc, soluble interleukin (IL)-1 receptor antagonist (sIL-1ra), soluble tumor necrosis factor receptor 1, soluble vascular endothelial cell adhesion molecule, and soluble intercellular adhesion molecule (sICAM)-1 were assayed on days 1 and 5. RESULTS: Compared with the placebo group, the zinc group had a shorter mean overall duration of cold (4.0 vs. 7.1 days; P < .0001) and shorter durations of cough (2.1 vs. 5.0 days; P < .0001) and nasal discharge (3.0 vs. 4.5 days, P = .02) Blinding of subjects was adequate, and adverse effects were comparable in the 2 groups. Symptom severity scores were decreased significantly in the zinc group. Mean changes in plasma levels of zinc, sIL-1ra, and ICAM-1 differed significantly between groups. CONCLUSION: Administration of zinc lozenges was associated with reduced duration and severity of cold symptoms. We related the improvement in cold symptoms to the antioxidant and anti-inflammatory properties of zinc.

Zinc up-regulates NF-kappaB activation via phosphorylation of IkappaB in HUT-78 (Th0) cells.

Nuclear factor of kappaB (NF-kappaB) is a major transcription factor regulating the expression of interleukin-2 (IL-2) and interleukin-2 receptor-alpha (IL-2Ralpha) in Th(1) cells. We previously demonstrated that zinc increased IL-2 and IL-2Ralpha production via NF-kappaB activation in HUT-78 (Th(0)) cells. However, the molecular mechanism is not well understood. In this study, we found that zinc increased phosphorylated IkappaB-alpha, NF-kappaB translocation and activation, as well as the production of IL-2 and IL-2Ralpha in wild type IkappaB gene transfected zinc-sufficient HUT-78 cells, compared to zinc-deficient HUT-78 cells. However, dominant negative IkappaB gene expression decreased these parameters in zinc-sufficient cells, suggesting that zinc increased NF-kappaB activation via IkappaB pathway.

Zinc supplementation decreases incidence of infections in the elderly: effect of zinc on generation of cytokines and oxidative stress.

BACKGROUND: Zinc deficiency, cell-mediated immune dysfunction, susceptibility to infections, and increased oxidative stress have been observed in elderly subjects (ie, those >55 y old). Zinc is an effective antiinflammatory and antioxidant agent. OBJECTIVES: The primary objective was to determine the effect of zinc on the incidence of total infections in healthy elderly subjects. The secondary objective was to determine the effect of zinc on cytokines and oxidative stress markers. DESIGN: A randomized, double-blind, placebo-controlled trial of zinc supplementation was conducted in elderly subjects. Fifty healthy subjects of both sexes aged 55-87 y and inclusive of all ethnic groups were recruited for this study from a senior center. The zinc-supplemented group received zinc gluconate (45 mg elemental Zn/d) orally for 12 mo. Incidence of infections during the supplementation period was documented. The generation of inflammatory cytokines, T helper 1 and T helper 2 cytokines, and oxidative stress markers and the plasma concentrations of zinc were measured at baseline and after supplementation. RESULTS: Compared with a group of younger adults, at baseline the older subjects had significantly lower plasma zinc, higher ex vivo generation of inflammatory cytokines and interleukin 10, and higher plasma oxidative stress markers and endothelial cell adhesion molecules. The incidence of infections and ex vivo generation of tumor necrosis factor alpha and plasma oxidative stress markers were significantly lower in the zinc-supplemented than in the placebo group. Plasma zinc and phytohemagglutin-induced interleukin 2 mRNA in isolated mononuclear cells were significantly higher in the zinc-supplemented than in the placebo group. CONCLUSIONS: After zinc supplementation, the incidence of infections was significantly lower, plasma zinc was significantly higher, and generation of tumor necrosis factor alpha and oxidative stress markers was significantly lower in the zinc-supplemented than in the placebo group.

Correction of interleukin-2 gene expression by in vitro zinc addition to mononuclear cells from zinc-deficient human subjects: a specific test for zinc deficiency in humans.

A nutritional deficiency of zinc in humans is widespread in the developing world, and a conditioned zinc deficiency is observed in many diseased states, the elderly population, and pregnant women of both developed and developing nations. It was recently reported that zinc is required for Nuclear Factor-kappaB (NF-kappaB) activation and gene expressions of both interleukin-2 (IL-2) and interleukin-2 receptor alpha (IL-2Ralpha) and beta in HUT-78, a Th0 human malignant lymphoblastoid cell line. In this study, it has been reported for the first time that zinc is also required for gene expression of IL-2 and IL-2Ralpha in primary cells. Isolated peripheral blood mononuclear cells (MNCs) from zinc-deficient elderly subjects was used for this study. NF-kappaB activation was shown to have decreased in the MNCs from zinc-deficient subjects, which was corrected by in vivo zinc supplementation. It was further shown that either in vivo zinc supplementation or the addition of zinc in vitro to MNCs from zinc-deficient subjects results in correction of the gene expression of IL-2 and IL-2Ralpha. Therefore, it was proposed that in vitro addition of zinc to MNCs for correction of gene expression of IL-2 in humans may be used as a specific test for zinc deficiency. Although currently no known specific laboratory test exists for the diagnosis of zinc deficiency in humans, the use of correction of IL-2 messenger RNA (mRNA) with in vitro zinc addition to MNCs from zinc-deficient subjects may be very useful.

Evidence for reprogramming global gene expression during zinc deficiency in the HUT-78 cell line.

OBJECTIVE: Investigations using cell lines, primary cells, animal models, and human subjects have provided data to indicate that zinc-deficient conditions affect immune functioning of myeloid and lymphoid cells. We hypothesized that zinc-deficient conditions alone may induce the expression of genes in lymphoid cells, which favor enhanced responses to myeloid molecules even in the absence of myeloid cells or myeloid factors. Our objective was to investigate the effects of low zinc-induced alterations in gene expression in a single lymphoid cell line in the absence of influences from growth factors and/or cytokines generated by other cell types also being affected by low zinc status. METHODS: Microarray analysis of non-stimulated and phytohemagglutinin-p/phorbol 12-myristate 13-acetate-stimulated zinc-deficient and zinc-adequate human-derived HUT-78 (TH(0)) lymphoblasts was used to identify changes in gene expressions associated solely with zinc-deficient status in these cells. RESULTS: Overall, gene expression for molecules that would increase T-lymphocyte response to signals from myeloid cells such as cytokine receptors and selected adhesion molecules were upregulated, whereas those associated with T-lymphocyte-directed immune functions, interleukin-2 and interleukin-6 receptors, the cytokine interleukin-4, and zinc finger transcription factors were downregulated. Analysis of selected data obtained from healthy, but mildly zinc-deficient human subjects corroborated observations obtained from low zinc-altered gene expression in HUT-78 cells. CONCLUSION: These data provide evidence for a shift in gene expression of molecules that would increase lymphoid responses to myeloid driven pathways during periods of zinc deficiency even in the absence of myeloid-derived stimuli.

Toxic effect of zinc on NF-kappaB, IL-2, IL-2 receptor alpha, and TNF-alpha in HUT-78 (Th(0)) cells.

Zinc deficiency decreased cellular immune response. Zinc supplementation reverses this response. High concentration of zinc intake is reported to alter immune response. We hypothesize that higher concentration of zinc adversely affects T-cell immune response. In this study, we examined whether higher concentration of zinc affects expression of IL-2, IL-2Ralpha, and TNF-alpha, and NF-kappaB activation in HUT-78 (Th(0)) cells. The results show that HUT-78 cells incubated in 15, 50, and 100 microM zinc medium had significantly higher intracellular zinc contents and faster growth after 4 days of incubation, compared to the cells incubated in 1 microM zinc medium. After PMA/PHA stimulation, 1 microM zinc showed significant decreases in NF-kappaB activation, and in the levels of IL-2, IL-2Ralpha, and TNF-alpha production and mRNAs compared to 15 microM zinc. The cells incubated in higher concentrations of zinc (50 and 100 microM zinc) showed mild to moderate decreases in the levels of IL-2, IL-2Ralpha, and TNF-alpha production and mRNAs, and in NF-kappaB activation compared to those incubated in 15 microM zinc medium. These data indicate that not only low level of zinc, but also high levels of zinc decrease Th1 function.

Antioxidant effect of zinc in humans.

Oxidative stress is known to be an important contributing factor in many chronic diseases. We tested the hypothesis that in healthy normal volunteers zinc acts as an effective anti-inflammatory and antioxidant agent. Ten normal volunteers were administered daily oral zinc supplementation (45 mg zinc as gluconate) and 10 volunteers received placebo for 8 weeks. Plasma zinc, MDA, HAE, and 8-OHdG levels; LPS-induced TNF-alpha and IL-1beta mRNA; and ex vivo TNF-alpha-induced NF-kappaB activity in mononuclear cells (MNC) were determined before and after supplementation. In subjects receiving zinc, plasma levels of lipid peroxidation products and DNA adducts were decreased, whereas no change was observed in the placebo group. LPS-stimulated MNC isolated from zinc-supplemented subjects showed reduced mRNA for TNF-alpha and IL-1beta compared to placebo. Ex vivo, zinc protected MNC from TNF-alpha-induced NF-kappaB activation. In parallel studies using HL-60, a promyelocytic cell line, we observed that zinc enhances the upregulation of mRNA and DNA-specific binding for A20, a transactivating factor which inhibits the activation of NF-kappaB. Our results suggest that zinc supplementation may lead to downregulation of the inflammatory cytokines through upregulation of the negative feedback loop A20 to inhibit induced NF-kappaB activation. Zinc administration to human subjects with conditions associated with increased oxidative stress should be explored.

Factors affecting bryostatin 1-enhanced 2-CdA cytotoxicity in resistant B-cell chronic lymphocytic leukemia.

Pre-treatment with bryostatin 1 (bryo) has been shown to potentiate the efficacy of (2-chloro-2-deoxyadenosine, cladribine, 2-CdA) in B-cell chronic lymphocytic leukemia (B-CLL) by increasing the ratio of deoxycytidine kinase (dCK) to 5'-nucleotidase (5'-NT) activity. The bryo-induced increase in dCK/5'-NT activity alone has not been a conclusive indication of final clinical outcome. Therefore, we used an ex vivo assay to investigate factors which may affect the bryo-induced enhancement of 2-CdA efficacy in B-CLL patient-derived samples. Bryo-induced increase in dCK/5'-NT was inversely associated with Rai stage CLL (r=-0.86). Increased dCK/5'-NT activity was not correlated with increased efficacy (cell death) or percentage of cellular [8-3H]-2-CdA converted to [8-3H]-2-CdATP ex vivo. Bryo pre-treatment increased the cellular uptake of [8-3H]-2-CdA and incorporation of [8-3H]-2-CdA metabolites into the DNA fraction. Cell death from 2-CdA was inversely correlated with bryo-induced activity of the DNA repair enzyme, DNA-PKcs, (r=-0.77). Thus, the ability of B-CLL to repair damaged DNA may be a more important predictor of the response to bryo/2-CdA and eventual clinical outcome than dCK/5'-NT activity. Additional CLL patients under bryo-2-CdA therapy are needed to verify these important observations.