Contribution of reactive oxygen species to the regulation of Glut1 in two hemopoietic cell lines differing in cytokine sensitivity

Modified citrus pectin inhibits breast cancer development in mice by targeting tumor-associated macrophage survival and polarization in hypoxic microenvironment

Large amounts of tumor-associated macrophages (TAM), which are predominately localized in hypoxia area of the tumor tissue, are associated with the malignant progression of the tumor. In the present study, we investigated the inhibitory effects of modified citrus pectin (MCP), a natural dietary polysaccharide, on the survival and polarization of TAM in relation to its inhibition on the growth and migration of breast cancer. M2 macrophages polarized from human monocyte THP-1 were chosen as a model for TAM. We showed that MCP (0.06%-1%) concentration-dependently suppressed the survival of TAM through inhibiting glucose uptake with a greater extent in hypoxia than in normoxia. Furthermore, MCP treatment decreased ROS level in TAM through its reducibility and inhibiting galectin-3 expression, leading to inhibition of glucose transporter-1 expression and glucose uptake. In addition, MCP suppressed M2-like polarization via inhibiting STAT3 phosphorylation. Moreover, the tumor-promoting effect of TAM could be restrained by MCP treatment as shown in human breast cancer MDA-MB-231 cells in vitro and in mouse breast cancer 4T1-luc orthotopic and metastasis models. In both tumor tissue and lung tissue of the mouse tumor models, the number of TAM was significantly decreased after MCP treatment. Taken together, MCP may be a promising agent for targeting TAM in tumor hypoxic microenvironment for breast cancer treatment.

Diagnostic and Predictive Values of 18F-FDG PET/CT Metabolic Parameters in EGFR-Mutated Advanced Lung Adenocarcinoma

Purpose

The clinical implications of the metabolic parameters of ¹⁸F-fluorodeoxyglucose positron emission tomography-computed tomography (¹⁸F-FDG PET/CT) in epidermal growth factor receptor (EGFR)-mutated lung cancer are not fully understood. The aim of this study was to evaluate the diagnostic and prognostic utility of the parameters in EGFR-mutated lung cancer patients.

Patients and Methods

We retrospectively enrolled 134 patients with advanced lung adenocarcinoma (72 EGFR-negative and 62 EGFR-positive). We evaluated the correlation between EGFR mutational status and the maximum standardized uptake value (SUVmax), as well as the associations between treatment outcomes in EGFR-mutated patients and various metabolic parameters of primary tumors. For the best predictive parameters, we calculated the metabolic tumor volume (MTV) and total lesion glycolysis (TLG) using two SUV cutoffs: 1.5 (MTV_1.5, TLG_1.5) and 2.5 (MTV_2.5, TLG_2.5).

Results

Mean SUVmax was lower for EGFR-mutated tumors compared with EGFR wild-type (6.11 vs 10.41, p < 0.001) tumors. Low SUVmax was significantly associated with positive EGFR mutation (odds ratio = 1.74). Multivariate analysis for survival demonstrated that high MTV_1.5, TLG_1.5, MTV_2.5, and TLG_2.5 were independently associated with shorter progression-free survival (PFS) and overall survival (OS), and the highest hazard ratios were found in TLG_1.5 (3.26 for PFS and 4.62 for OS).

Conclusion

SUVmax may be predictive for EGFR mutational status, and MTV and TLG of primary tumors may be promising prognostic parameters; ¹⁸F-FDG PET/CT has potential utility for the risk stratification of EGFR-mutated patients treated with targeted therapy.

Peroxiporins in Cancer

The transport of H₂O₂ across membranes by specific aquaporins (AQPs) has been considered the last milestone in the timeline of hydrogen peroxide discoveries in biochemistry. According to its concentration and localization, H₂O₂ can be dangerous or acts as a signaling molecule in various cellular processes as either a paracrine (intercellular) and/or an autocrine (intracellular) signal. In this review, we investigate and critically examine the available information on AQP isoforms able to facilitate H₂O₂ across biological membranes (“peroxiporins”), focusing in particular on their role in cancer. Moreover, the ability of natural compounds to modulate expression and/or activity of peroxiporins is schematically reported and discussed.

Vimentin deficiency in macrophages induces increased oxidative stress and vascular inflammation but attenuates atherosclerosis in mice

The aim was to clarify the role of vimentin, an intermediate filament protein abundantly expressed in activated macrophages and foam cells, in macrophages during atherogenesis. Global gene expression, lipid uptake, ROS, and inflammation were analyzed in bone-marrow derived macrophages from vimentin-deficient (Vim-/-) and wild-type (Vim+/+) mice. Atherosclerosis was induced in Ldlr-/- mice transplanted with Vim-/- and Vim+/+ bone marrow, and in Vim-/- and Vim+/+ mice injected with a PCSK9 gain-of-function virus. The mice were fed an atherogenic diet for 12-15 weeks. We observed impaired uptake of native LDL but increased uptake of oxLDL in Vim-/- macrophages. FACS analysis revealed increased surface expression of the scavenger receptor CD36 on Vim-/- macrophages. Vim-/- macrophages also displayed increased markers of oxidative stress, activity of the transcription factor NF-κB, secretion of proinflammatory cytokines and GLUT1-mediated glucose uptake. Vim-/- mice displayed decreased atherogenesis despite increased vascular inflammation and increased CD36 expression on macrophages in two mouse models of atherosclerosis. We demonstrate that vimentin has a strong suppressive effect on oxidative stress and that Vim-/- mice display increased vascular inflammation with increased CD36 expression on macrophages despite decreased subendothelial lipid accumulation. Thus, vimentin has a key role in regulating inflammation in macrophages during atherogenesis.

EGFR mutation decreases FDG uptake in non‑small cell lung cancer via the NOX4/ROS/GLUT1 axis

[18F]fluoro‑2‑deoxyglucose (FDG) positron emission tomography (PET)‑computed tomography (CT) is a functional imaging modality based on glucose metabolism. The association between the maximum standardized uptake value (SUVmax) from 18F‑FDG PET‑CT scanning and epidermal growth factor receptor (EGFR) mutation status has, to the best of our knowledge, not previously been fully elucidated, and the potential mechanisms by which EGFR mutations alter FDG uptake are largely unknown. A total of 157 patients who were pathologically diagnosed with non‑small cell lung cancer (NSCLC) who underwent EGFR mutation testing and PET‑CT pretreatment between June 2015 and October 2017 were retrospectively analyzed. χ2 and univariate analyses were performed to identify the contributors to EGFR mutation. The receiver operating characteristic (ROC) curve was analyzed, and the area under the curve (AUC) was calculated. Glucose transporter 1 (GLUT1) and NADPH oxidase 4 (NOX4) expression, and reactive oxygen species (ROS) activity were detected in the A549 (wild‑type), PC‑9 (EGFR mutation‑positive, EGFR exon 19del) and NCI‑H1975 (EGFR mutation‑positive, combined with L858R and T790M substitution) cell lines. A total of 109 patients who met the criteria were enrolled, and 63 of those tested as EGFR mutation‑positive. The SUVmax values were significantly lower in patients with EGFR mutations (mean, 6.52±0.38) compared with in patients with wild‑type EGFR (mean, 9.37±0.31; P<0.001). Using univariate analysis, EGFR mutation status was significantly associated with sex, smoking status, tumor histology and SUVmax of the primary tumor. In the multivariate analysis, smoking status (never‑smoking), histopathology (adenocarcinoma) and SUVmax (≤9.91) were the statistically significant predictors of EGFR mutations. ROC curve analysis identified that the SUVmax cut‑off point was 9.92, for which the AUC was 0.75 (95% confidence interval, 0.68‑0.83). Reverse transcription‑polymerase chain reaction indicated that the GLUT1 mRNA decreased in the PC‑9 and NCI‑H1975 cell lines compared with the A549 cell line (0.82±0.07 and 0.72±0.04 vs. 0.98±0.04, respectively; P<0.05) and decreased ROS activity was observed in the PC‑9 cell line. Furthermore, the expression of NOX4 mRNA decreased by 20% in PC‑9 (P<0.01) and by 14% (P<0.05) in NCI‑H1975 cells. In addition, NOX4 protein expression decreased by 13% in PC‑9 and by 16% in NCI‑H1975 cells (both P<0.05) compared with the A549 cell line. The SUVmax could be considered to effectively predict EGFR mutation status of patients with NSCLC, and the EGFR mutation status may alter FDG uptake partially via the NOX4/ROS/GLUT1 axis.

Steviol glycosides modulate glucose transport in different cell types

Extracts from Stevia rebaudiana Bertoni, a plant native to Central and South America, have been used as a sweetener since ancient times. Currently, Stevia extracts are largely used as a noncaloric high-potency biosweetener alternative to sugar, due to the growing incidence of type 2 diabetes mellitus, obesity, and metabolic disorders worldwide. Despite the large number of studies on Stevia and steviol glycosides in vivo, little is reported concerning the cellular and molecular mechanisms underpinning the beneficial effects on human health. The effect of four commercial Stevia extracts on glucose transport activity was evaluated in HL-60 human leukaemia and in SH-SY5Y human neuroblastoma cells. The extracts were able to enhance glucose uptake in both cellular lines, as efficiently as insulin. Our data suggest that steviol glycosides could act by modulating GLUT translocation through the PI3K/Akt pathway since treatments with both insulin and Stevia extracts increased the phosphorylation of PI3K and Akt. Furthermore, Stevia extracts were able to revert the effect of the reduction of glucose uptake caused by methylglyoxal, an inhibitor of the insulin receptor/PI3K/Akt pathway. These results corroborate the hypothesis that Stevia extracts could mimic insulin effects modulating PI3K/Akt pathway.

Redox regulation of stem/progenitor cells and bone marrow niche

Bone marrow (BM)-derived stem and progenitor cell functions including self-renewal, differentiation, survival, migration, proliferation, and mobilization are regulated by unique cell-intrinsic and -extrinsic signals provided by their microenvironment, also termed the "niche." Reactive oxygen species (ROS), especially hydrogen peroxide (H(2)O(2)), play important roles in regulating stem and progenitor cell functions in various physiologic and pathologic responses. The low level of H(2)O(2) in quiescent hematopoietic stem cells (HSCs) contributes to maintaining their "stemness," whereas a higher level of H(2)O(2) within HSCs or their niche promotes differentiation, proliferation, migration, and survival of HSCs or stem/progenitor cells. Major sources of ROS are NADPH oxidase and mitochondria. In response to ischemic injury, ROS derived from NADPH oxidase are increased in the BM microenvironment, which is required for hypoxia and hypoxia-inducible factor-1α expression and expansion throughout the BM. This, in turn, promotes progenitor cell expansion and mobilization from BM, leading to reparative neovascularization and tissue repair. In pathophysiological states such as aging, atherosclerosis, heart failure, hypertension, and diabetes, excess amounts of ROS create an inflammatory and oxidative microenvironment, which induces cell damage and apoptosis of stem and progenitor cells. Understanding the molecular mechanisms of how ROS regulate the functions of stem and progenitor cells and their niche in physiological and pathological conditions will lead to the development of novel therapeutic strategies.

Stem Cell Factor Receptor/c-Kit: From Basic Science to Clinical Implications

Stem cell factor (SCF) is a dimeric molecule that exerts its biological functions by binding to and activating the receptor tyrosine kinase c-Kit. Activation of c-Kit leads to its autophosphorylation and initiation of signal transduction. Signaling proteins are recruited to activated c-Kit by certain interaction domains (e.g., SH2 and PTB) that specifically bind to phosphorylated tyrosine residues in the intracellular region of c-Kit. Activation of c-Kit signaling has been found to mediate cell survival, migration, and proliferation depending on the cell type. Signaling from c-Kit is crucial for normal hematopoiesis, pigmentation, fertility, gut movement, and some aspects of the nervous system. Deregulated c-Kit kinase activity has been found in a number of pathological conditions, including cancer and allergy. The observation that gain-of-function mutations in c-Kit can promote tumor formation and progression has stimulated the development of therapeutics agents targeting this receptor, e.g., the clinically used inhibitor imatinib mesylate. Also other clinically used multiselective kinase inhibitors, for instance, sorafenib and sunitinib, have c-Kit included in their range of targets. Furthermore, loss-of-function mutations in c-Kit have been observed and shown to give rise to a condition called piebaldism. This review provides a summary of our current knowledge regarding structural and functional aspects of c-Kit signaling both under normal and pathological conditions, as well as advances in the development of low-molecular-weight molecules inhibiting c-Kit function.

Effect of plasma membrane cholesterol depletion on glucose transport regulation in leukemia cells

GLUT1 is the predominant glucose transporter in leukemia cells, and the modulation of glucose transport activity by cytokines, oncogenes or metabolic stresses is essential for their survival and proliferation. However, the molecular mechanisms allowing to control GLUT1 trafficking and degradation are still under debate. In this study we investigated whether plasma membrane cholesterol depletion plays a role in glucose transport activity in M07e cells, a human megakaryocytic leukemia line. To this purpose, the effect of cholesterol depletion by methyl-β-cyclodextrin (MBCD) on both GLUT1 activity and trafficking was compared to that of the cytokine Stem Cell Factor (SCF). Results show that, like SCF, MBCD led to an increased glucose transport rate and caused a subcellular redistribution of GLUT1, recruiting intracellular transporter molecules to the plasma membrane. Due to the role of caveolae/lipid rafts in GLUT1 stimulation in response to many stimuli, we have also investigated the GLUT1 distribution along the fractions obtained after non ionic detergent treatment and density gradient centrifugation, which was only slightly changed upon MBCD treatment. The data suggest that MBCD exerts its action via a cholesterol-dependent mechanism that ultimately results in augmented GLUT1 translocation. Moreover, cholesterol depletion triggers GLUT1 translocation without the involvement of c-kit signalling pathway, in fact MBCD effect does not involve Akt and PLCγ phosphorylation. These data, together with the observation that the combined MBCD/SCF cell treatment caused an additive effect on glucose uptake, suggest that the action of SCF and MBCD may proceed through two distinct mechanisms, the former following a signalling pathway, and the latter possibly involving a novel cholesterol dependent mechanism.

Dietary phenolic acids act as effective antioxidants in membrane models and in cultured cells, exhibiting proapoptotic effects in leukaemia cells

Caffeic, syringic, and protocatechuic acids are phenolic acids derived directly from food intake or come from the gut metabolism of polyphenols. In this study, the antioxidant activity of these compounds was at first evaluated in membrane models, where caffeic acid behaved as a very effective chain-breaking antioxidant, whereas syringic and protocatechuic acids were only retardants of lipid peroxidation. However, all three compounds acted as good scavengers of reactive species in cultured cells subjected to exogenous oxidative stress produced by low level of H(2)O(2). Many tumour cells are characterised by increased ROS levels compared with their noncancerous counterparts. Therefore, we investigated whether phenolic acids, at low concentrations, comparable to those present in human plasma, were able to decrease basal reactive species. Results show that phenolic acids reduced ROS in a leukaemia cell line (HEL), whereas no effect was observed in normal cells, such as HUVEC. The compounds exhibited no toxicity to normal cells while they decreased proliferation in leukaemia cells, inducing apoptosis. In the debate on optimal ROS-manipulating strategies in cancer therapy, our work in leukaemia cells supports the antioxidant ROS-depleting approach.

NAD(P)H oxidase isoform Nox2 plays a prosurvival role in human leukaemia cells

The mechanism involved in the prosurvival effect of interleukin-3 on the human acute myeloid leukaemia cell line M07e is investigated. A decrease in intracellular reactive oxygen species (ROS) content, glucose transport activity and cell survival was observed in the presence of inhibitors of plasma membrane ROS sources, such as diphenylene iodonium and apocynin, and by small interference RNA for Nox2. Moreover, IL-3 incubation stimulated the synthesis of Nox2 cytosolic sub-unit p47phox and glucose transporter Glut1. Thus, the inhibition of ROS generation by Nox inhibitors stimulated apoptosis showing that ROS production, induced by IL-3 via Nox2, protects leukaemic cells from cell death. Also incubation with receptor tyrosine kinase inhibitors, such as anti-leukaemic drugs blocking the stem cell factor receptor (c-kit), showed similar effects, hinting that IL-3 transmodulates c-kit phosphorylation. These mechanisms may play an important role in acute myeloid leukaemia treatment, representing a novel therapeutic target.

Inhibition of trans-plasma membrane electron transport: a potential anti-leukemic strategy

The recently demonstrated reliance of glycolytic cancer cells on trans-plasma membrane electron transport (tPMET) for survival raises the question of its suitability as a target for anticancer drug development. In this study, the effects of several new and known compounds on proliferation, tPMET activity and NAD(P)H intrinsic fluorescence in human myelogenous leukemic cell lines were investigated. The whole data confirm the importance of tPMET in leukemic cell survival and suggest this activity as a new potential anti-leukemic target.

Heavy ion beam irradiation regulates the mRNA expression in megakaryocytopoiesis from human hematopoietic stem/progenitor cells

Heavy ion beams are a high-LET radiation that has greater biological effect than electron beams or X-rays. However, little is known about the effect of heavy ion beams on the proliferation and differentiation of human hematopoietic stem/progenitor cells (HSPCs). The present study examined the effect of heavy ion beams on gene expression in human HSPCs, especially during early stage of megakaryocytopoiesis. Human CD34+ cells were exposed to monoenergetic carbon-ion beams (290 MeV/nucleon, LET = 50 KeV/m) that were generated by an accelerator (Heavy Ion Medical Accelerator in Chiba). The expression of various genes related to early hematopoiesis, megakaryocytopoiesis/erythropoiesis, cytokine receptors and oxidative stress were analyzed by real-time RT-PCR. Friend leukemia virus integration 1, an early hematopoiesis-related gene, showed significantly higher mRNA expression than the control at 6 hr after irradiation. In contrast, no significant differences were observed in almost all of the other early hematopoiesis-related genes, cytokine receptor-coded genes and megakaryocytopoiesis/erythropoiesis-differentiation pathway-related genes, respectively. An analysis of the response of the genes to oxidative stress revealed the expression of heme oxygenase 1 to show a 1.5-fold and 11.9-fold increase from the day 0 control at 24 hr after 0.5 Gy and 2 Gy irradiation, respectively. Similarly, the NAD(P)H dehydrogenase-quinone 1 expression also showed a 22.0-fold and a 21.8-fold increase at 6 hr in comparison to the initial control. These results showed that the heavy ion beams affect megakaryocytopoiesis/ erythropoiesis differentiation of human HSPCs on the gene expression level.

Differential expression of NADPH oxidases in megakaryocytes and their role in polyploidy

Megakaryocytes (MKs) undergo an endomitotic cell cycle, leading to polyploidy. We examined the expression of the flavoproteins and oxidative stress-promoting enzymes, NADPH oxidases (Nox's), in MKs because of their known role in promoting the cell cycle. Although the expression of Nox isoforms varies between cell types, they are induced at the mRNA level by mitogenic stimuli. Western blotting or reverse transcription-polymerase chain reaction of purified mouse MKs isolated from thrombopoietin (TPO)-treated bone marrow (BM) cultures indicated high expression of Nox1, a weak expression of Nox4, and no significant expression of Nox2. Immunofluorescence of freshly isolated MKs confirmed strong expression of Nox1 in one-third of MKs, whereas Nox1 staining was detected in nearly all MKs in TPO-stimulated BM cultures. Treatment of mouse BM cultures with Nox inhibitors resulted in accumulation of MKs with low DNA content levels and significant reduction of higher ploidy MKs. Purified, Nox-inhibited MKs showed a notable decrease in the level of the G(1) phase cyclin E, a cyclin associated with MK polyploidy, and its up-regulation restored most of the effect of Nox inhibitors. Hence, this study shows the expression of Nox isoforms in MKs and highlights a potential role of flavoproteins in promoting polyploidization in this lineage.

Induction of apoptosis in a human leukemic cell line via reactive oxygen species modulation by antioxidants

In the human acute myeloid leukemia cell line M07e, the growth factor interleukin-3 (IL-3) induces ROS formation, positively affecting Glut1-mediated glucose uptake and cell survival. The effect of IL-3 and exogenous hydrogen peroxide on cell viability seems to be mediated through inhibition of the cell death commitment, as shown by apoptotic markers such as caspase activities, apoptotic nuclei, and changes in the amount of proteins belonging to the Bcl-2 family. The pivotal role of ROS is confirmed using various antioxidants, such as EUK-134, ebselen, TEMPO, and hydroxylamine probe. In fact, these antioxidants, acting through different mechanisms, decrease glucose transport activity and cell proliferation activated by IL-3 or by low concentrations of hydrogen peroxide. Moreover, antioxidants foster programmed cell death commitment, as shown by the cited apoptotic parameters. EUK-134, a combined superoxide dismutase/catalase mimetic, opposes the effects of IL-3 and H(2)O(2), decreasing phosphorylation levels of signaling enzymes such as Akt, Src tyrosine kinase, and ERK. Results show that ROS production induced by IL-3 can protect leukemic cells from apoptosis, the effect being counteracted by antioxidants. This mechanism may play an important role in supporting acute myeloid leukemia treatment, thus representing a novel therapeutic strategy.

Cell cycle regulation by oncogenic tyrosine kinases in myeloid neoplasias: from molecular redox mechanisms to health implications

Neoplastic expansion of myeloid cells is associated with specific genetic changes that lead to chronic activation of signaling pathways, as well as altered metabolism. It has become increasingly evident that transformation relies on the interdependency of both events. Among the various genetic changes, the oncogenic BCR-ABL tyrosine kinase in patients with Philadelphia chromosome positive chronic myeloid leukemia (CML) has been a focus of extensive research. Transformation by this oncogene is associated with elevated levels of intracellular reactive oxygen species (ROS). ROS have been implicated in processes that promote viability, cell growth, and regulation of other biological functions such as migration of cells or gene expression. Currently, the BCR-ABL inhibitor imatinib mesylate (Gleevec) is being used as a first-line therapy for the treatment of CML. However, BCR-ABL transformation is associated with genomic instability, and disease progression or resistance to imatinib can occur. Imatinib resistance is not known to cause or significantly alter signaling requirements in transformed cells. Elevated ROS are crucial for transformation, making them an ideal additional target for therapeutic intervention. The underlying mechanisms leading to elevated oxidative stress are reviewed, and signaling mechanisms that may serve as novel targeted approaches to overcome ROS-dependent cell growth are discussed.

Lipotoxic effects of triacylglycerols in J774.2 macrophages

OBJECTIVE

Triacylglycerols (TGs) are being considered as an independent risk factor in atherosclerosis and metabolic syndrome, acting by dysregulation of the TG/high-density lipoprotein axis. Accumulation of lipids in subendothelial space attracts macrophages, leading to atherosclerotic plaque formation and increased plaque instability due to formation of foam cells and macrophage death. The aim of this study was to evaluate lipotoxic effects in macrophages caused by TG uptake.

METHODS

J774.2 macrophages were exposed to soybean or olive oil-based lipid emulsions as a source of TGs (1 mg/mL) in a presence or absence of lipase inhibitor paraoxon (20 microM) or to bovine serum albumin-complexed palmitic (150 microM), linoleic (600 microM), and oleic (600 microM) fatty acids.

RESULTS

The results demonstrated accumulation of TGs, G1/S arrest, and cell death with necrotic morphologic features after exposure to TG emulsions. These effects were prevented by treatment with an antioxidant N-acetyl-cysteine (0.5 mM). Paraoxon inhibited intracellular TG degradation but did not prevent lipotoxicity and cell death. Olive oil TG triggered macrophage death in a manner similar to soybean oil. Treatment of the macrophages with free fatty acid, mainly with palmitic acid, showed a reactive oxygen species-independent cell death pathway, which was different from that of TG and was not prevented by N-acetyl-cysteine.

CONCLUSION

This study shows a direct lipotoxic pathway for TG molecules in macrophages, which is not associated with degradation of TG molecule to free fatty acids. This study for the first time can explain at a cellular level how TGs as an independent risk factor aggravate atherosclerotic outcomes.

Glucose-transport regulation in leukemic cells: how can H2O2 mimic stem cell factor effects?

In leukemic cells, glucose transport is activated by SCF and H2O2 through a common signal cascade involving Akt, PLCgamma, Syk, and the Src family, in this order. An explanation can be provided by the phosphorylation of c-kit, the SCF receptor, elicited by either SCF or H2O2. Moreover, antioxidants prevent the SCF effect on glucose transport, confirming the involvement of H2O2 in the pathway leading to glucose-transport activation and suggesting a potential role for reactive oxygen species in leukemia proliferation.

Glucose transport activation in human hematopoietic cells M07e is modulated by cytosolic calcium and calmodulin

The aim of this work was to investigate the role of cytosolic calcium and calmodulin-dependent systems in the activation of glucose uptake in the human megakaryocytic cell line M07e. Glucose uptake was significantly raised by elevation of cytosolic Ca(2+) concentration ([Ca(2+)](c)) with thapsigargin, this effect being additive to the activation induced by cytokines (SCF, GM-CSF and TPO) and hydrogen peroxide. Intracellular Ca(2+) chelation by BAPTA decreased basal and activated glucose uptake in a dose-dependent manner. BAPTA reduced the GLUT1 translocation induced by SCF and H(2)O(2), suggesting a major role for Ca(2+) in GLUT1 intracellular trafficking. In the absence of extracellular Ca(2+), 2-aminoethoxydiphenyl-borate (2-APB) abolished the activation of glucose uptake induced by cytokines and H(2)O(2) suggesting an involvement in GLUT1 regulation in responses related to InsP(3)-induced Ca(2+) release. Under our experimental conditions, all the stimuli inducing glucose uptake activation failed to increase [Ca(2+)](c) suggesting that cytosolic Ca(2+) plays a permissive role in the regulation of GLUT1. The calmodulin antagonist W-7 and the inhibitor of Ca(2+)-calmodulin dependent protein kinase II (CAMK II) KN-62 removed the glucose transport activation by all the tested stimuli. These results suggest that in M07e cells calmodulin and CAMKII are involved in GLUT1 stimulation by cytokines and ROS.