ascorbic-acid and Leukemia

Topics: Administration, Oral; Aged; Antigen-Antibody Reactions; Ascorbic Acid; Aspirin; Child; Common Cold; Female; Fenfluramine; Humans; Hypersensitivity; Leukemia; Leukocytes; Lung Neoplasms; Male; Mouth Mucosa; Nutritional Requirements; Scurvy

Topics: Animals; Ascorbic Acid; Ascorbic Acid Deficiency; Carcinoma 256, Walker; Guinea Pigs; Leukemia; Neoplasms; Neoplasms, Experimental; Rats; Research; Sarcoma; Sarcoma, Experimental; Sarcoma, Yoshida

Arsenic trioxide (As(2)O(3)) has established clinical activity in acute promyelocytic leukaemia and has pre-clinical data suggesting activity in lymphoid malignancies. Cell death from As(2)O(3) may be the result of oxidative stress. Agents which deplete intracellular glutathione, such as ascorbic acid (AA), may potentiate arsenic-mediated apoptosis. This multi-institution phase II study investigated a novel dosing schedule of As(2)O(3) and AA in patients with relapsed or refractory lymphoid malignancies. Patients received As(2)O(3) 0.25 mg/kg iv and AA 1000 mg iv for five consecutive days during the first week of each cycle followed by twice weekly infusions during weeks 2-6. Cycles were repeated every 8 weeks. The primary end point was objective response. In a subset of patients, sequential levels of intracellular glutathione and measures of Bcl-2 and Bax gene expression were evaluated in peripheral blood mononuclear cells during treatment. Seventeen patients were enrolled between March 2002 and February 2004. The median age was 71, and the majority of enrolled patients had non-Hodgkin's lymphoma (12/17). Sixteen patients were evaluable, and one patient with mantle cell lymphoma achieved an unconfirmed complete response after five cycles of therapy for an overall response rate of 6%. The trial, which had been designed as a two-stage study, was closed after the first stage analysis due to lack of activity. Haematologic toxicities were the most commonly reported events in this heavily pre-treated population, and comprised the majority of grade 3 and 4 toxicities. Intracellular depletion of glutathione was not consistently observed during treatment. As(2)O(3) and AA in this novel dosing strategy was generally well tolerated but had limited activity in patients with relapsed and refractory lymphoid malignancies.

Topics: Adult; Aged; Aged, 80 and over; Arsenic Trioxide; Arsenicals; Ascorbic Acid; Female; Glutathione; Humans; Leukemia; Leukemia, Lymphocytic, Chronic, B-Cell; Lymphoma; Lymphoma, Non-Hodgkin; Male; Middle Aged; Oxides; Safety

Conditioning therapy preceding bone marrow transplantation (BMT) usually consists of high-dose chemotherapy and total body irradiation (TBI). It has acute and delayed toxic effects on several tissues, possibly related to peroxidation processes and exhaustion of antioxidants. Early studies indicated an increase of peroxide processes and a decrease of antioxidants during conditioning therapy. Hence, we investigated the effect of antioxidant supplementation on peroxidation processes and antioxidant status. We supplemented a patient group (N = 16) [BMT (+)], with oral 45 mg beta-carotene, 825 mg alpha-tocopherol and 450 mg ascorbic acid daily for three weeks before conditioning therapy. Another patient group (N = 10), BMT(-), was not supplemented with antioxidants before conditioning therapy. In order to investigate the physiologic effect of supplement antioxidants a healthy control group (N = 10) was supplemented with the same doses as BMT(+). Peroxide concentrations in plasma were measured by using the cholesterol oxidase (CHOD)-iodide method and antioxidants were measured by HPLC. Before supplementation the beta-carotene and alpha-tocopherol concentrations were comparable in both patient groups. After supplementation significantly higher beta-carotene and alpha-tocopherol concentrations were measured in the supplemented patients, BMT(+), than in the unsupplemented patients, BMT(-). After conditioning therapy, BMT(+) patients showed a significantly higher beta-carotene concentration (p < 0.05) than before supplementation. In BMT(-) patients the beta-carotene (p < 0.05) and alpha-tocopherol concentrations (p < 0.01) decreased significantly and the lipid peroxide concentration increased significantly following conditioning therapy. We conclude that antioxidant supplementation prior to conditioning therapy reduces peroxidation processes induced by conditioning therapy in bone marrow recipients.

Topics: Adolescent; Adult; Antioxidants; Ascorbic Acid; beta Carotene; Bone Marrow Purging; Bone Marrow Transplantation; Dose-Response Relationship, Drug; Drug Therapy, Combination; Feasibility Studies; Female; Humans; Leukemia; Lipid Peroxidation; Male; Middle Aged; Premedication; Reactive Oxygen Species; Vitamin E

TET2 haploinsufficiency is a driving event in myeloid cancers and is associated with a worse prognosis in patients with acute myeloid leukemia (AML). Enhancing residual TET2 activity using vitamin C increases oxidized 5-methylcytosine (mC) formation and promotes active DNA demethylation via base excision repair (BER), which slows leukemia progression. We utilize genetic and compound library screening approaches to identify rational combination treatment strategies to improve use of vitamin C as an adjuvant therapy for AML. In addition to increasing the efficacy of several US Food and Drug Administration (FDA)-approved drugs, vitamin C treatment with poly-ADP-ribosyl polymerase inhibitors (PARPis) elicits a strong synergistic effect to block AML self-renewal in murine and human AML models. Vitamin-C-mediated TET activation combined with PARPis causes enrichment of chromatin-bound PARP1 at oxidized mCs and γH2AX accumulation during mid-S phase, leading to cell cycle stalling and differentiation. Given that most AML subtypes maintain residual TET2 expression, vitamin C could elicit broad efficacy as a PARPi therapeutic adjuvant.

Topics: Animals; Ascorbic Acid; Humans; Leukemia; Mice; Poly(ADP-ribose) Polymerase Inhibitors; Synthetic Lethal Mutations; Vitamins

Perfluorooctanesulfonate (PFOS) is a persistent pollutant that can induce toxic effects, including leukemia, on blood cells. Vitamin C (VC), a functional nutrient, has been found to possess potent cytoprotective effects. However, there are currently no reports on its ability to treat PFOS-associated leukemia. This study used a molecular networking analysis to reveal the functional action and pharmacological mechanism of VC against PFOS-associated leukemia. The biological informatics findings revealed a total of 17 intersection targets against PFOS-associated leukemia. In addition, seven core-functional targets, including tumor protein p53 (TP53), mitogen-activated protein kinase 1 (MAPK1), estrogen receptor 1 (ESR1), sirtuin 1 (SIRT1), nitric oxide synthase 3 (NOS3), myeloid cell leukemia-1 (MCL1), and telomerase reverse transcriptase (TERT), were screened and identified. Notably, the molecular docking findings indicated that TP53, MAPK1, and ESR1 were potent pharmacological targets of VC against PFOS-associated leukemia. Moreover, the pharmacological functions including biological processes, cell components, and molecular pathways of VC against PFOS-associated leukemia were determined. According to the computational findings, we conclude that VC protects against PFOS-associated leukemia action by suppressing leukemia-associated cell proliferation and tumor growth. The validated genes of TP53, MAPK1, ESR1 may become potential biomarkers for monitoring and treating PFOS-associated leukemia.

Topics: Alkanesulfonic Acids; Ascorbic Acid; Fluorocarbons; Humans; Leukemia; Molecular Docking Simulation; Signal Transduction

Adoptive transfer of induced regulatory T cells (iTregs) can ameliorate graft-versus-host disease (GVHD) after allogeneic hematopoietic cell transplantation (allo-HCT). CD4+ iTregs can effectively prevent GVHD but impair the graft-versus-leukemia (GVL) effect, whereas CD8+ iTregs preserve the GVL effect but have limited efficacy in GVHD control because of their instability under inflammatory conditions. Thus, we aimed to stabilize CD8+ iTregs via treatment with vitamin C (Vit C) to improve their efficacy in controlling GVHD. We found that addition of Vit C significantly improved the stability of forkhead box P3 (Foxp3) expression in CD8+ iTregs. Moreover, Vit C-treated CD8+ iTregs exhibited high efficacy in attenuating acute and chronic GVHD. The mechanistic study revealed that addition of Vit C to CD8+ iTreg culture markedly increased DNA demethylation in the conserved noncoding sequence 2 region and, hence, maintained higher Foxp3 expression levels compared with untreated controls. In acute GVHD, Vit C-treated CD8+ iTregs were able to inhibit pathogenic T-cell expansion and differentiation while reducing thymus damage and B-cell activation in cGVHD. Importantly, in contrast to CD4+ iTregs, Vit C-treated CD8+ iTregs retained the ability to control tumor relapse. These results provide a strong rationale to use Vit C in the clinic to stabilize CD8+ iTregs for the control of GVHD and preservation of GVL after allo-HCT.

Topics: Adoptive Transfer; Animals; Ascorbic Acid; Biomarkers; CD8-Positive T-Lymphocytes; Disease Models, Animal; DNA Methylation; Forkhead Transcription Factors; Graft vs Host Disease; Heterografts; Interferon-gamma; Leukemia; Lymphocyte Activation; Mice; Mice, Knockout; Recurrence; T-Lymphocytes, Regulatory

Recent studies provided convincing evidence for the anticancer activity of combined application of vitamin C and pro-vitamin K3 (menadione). The molecular pathways underlying this process are still not well established. The present study aimed to investigate the effect of the combination of vitamin C plus pro-vitamin K3 on the redox status of leukemia and normal lymphocytes, as well as their sensitizing effect for a variety of anticancer drugs.. Cytotoxicity of the substances was analyzed by trypan blue staining and automated counting of live and dead cells. Apoptosis was analyzed by fluorescein isothiocyanate-annexin V test. Oxidative stress was evaluated by the intracellular levels of reactive oxygen and nitrogen species and protein-carbonyl products.. Combined administration of 300 μM vitamin C plus 3 μM pro-vitamin K3 reduced the viability of leukemia lymphocytes by ~20%, but did not influence the viability of normal lymphocytes. All combinations of anticancer drug plus vitamins C and K3 were characterized by synergistic cytotoxicity towards Jurkat cells, compared to cells treated with drug alone for 24 h. In the case of barasertib and everolimus, this synergistic cytotoxicity increased within 72 hours. It was accompanied by strong induction of apoptosis, but a reduction of level of hydroperoxides and moderately increased protein-carbonyl products in leukemia cells.. Leukemia lymphocytes were more sensitive to combined administration of anticancer drug (everolimus or barasertib) plus vitamins C and K3, compared to normal lymphocytes. The combination of vitamin C plus K3 seems to be a powerful redox system that could specifically influence redox homeostasis of leukemia cells and sensitize them to conventional chemotherapy.

Topics: Antineoplastic Agents; Apoptosis; Ascorbic Acid; Cell Survival; Cells, Cultured; Everolimus; Humans; Jurkat Cells; Leukemia; Lipid Peroxides; Lymphocytes; Organophosphates; Protein Kinase Inhibitors; Quinazolines; Reactive Oxygen Species; Vitamin K 3; Vitamins

Although vitamin C (VC) has recently garnered interest as an alternative cancer therapy, its clinical effects remain controversial. It was recently reported using in vitro prostate cancer cell lines that excess extracellular iron (EEI) diminishes anti-cancer effects of VC, promoting the decomposition of hydrogen peroxide (H

Topics: Apoptosis; Ascorbic Acid; Cell Line, Tumor; Cell Proliferation; Humans; Hydrogen Peroxide; Iron; K562 Cells; Leukemia

Stem-cell fate can be influenced by metabolite levels in culture, but it is not known whether physiological variations in metabolite levels in normal tissues regulate stem-cell function in vivo. Here we describe a metabolomics method for the analysis of rare cell populations isolated directly from tissues and use it to compare mouse haematopoietic stem cells (HSCs) to restricted haematopoietic progenitors. Each haematopoietic cell type had a distinct metabolic signature. Human and mouse HSCs had unusually high levels of ascorbate, which decreased with differentiation. Systemic ascorbate depletion in mice increased HSC frequency and function, in part by reducing the function of Tet2, a dioxygenase tumour suppressor. Ascorbate depletion cooperated with Flt3 internal tandem duplication (Flt3

Topics: Animals; Ascorbic Acid; Ascorbic Acid Deficiency; Carcinogenesis; Dioxygenases; DNA-Binding Proteins; Female; fms-Like Tyrosine Kinase 3; Hematopoietic Stem Cells; Humans; Leukemia; Male; Metabolomics; Mice; Myelopoiesis; Proto-Oncogene Proteins

Topics: Ascorbic Acid; Humans; Leukemia; Neoplasms; Neoplastic Stem Cells; Stem Cells; Vitamins

Metabolic cues and (epi-)genetic factors are emerging regulators of hematopoietic stem cell (HSC) potency. Two new studies in Nature and Cell, from Agathocleous et al. (2017) and Cimmino et al. (2017), respectively, show that vitamin C regulates HSC function and suppresses leukemogenesis by modulating Tet2 activity.

Topics: Ascorbic Acid; Dioxygenases; Disease Progression; DNA-Binding Proteins; Hematopoietic Stem Cells; Humans; Leukemia; Proto-Oncogene Proteins

Quercetin (Que) is an abundant flavonoid in the human diet and high-concentration food supplement with reported pro- and anti-carcinogenic activities. Topoisomerase II (TopoII) inhibition and subsequent DNA damage induction by Que was implicated in the mixed lineage leukemia gene (MLL) rearrangements that can induce infant and adult leukemias. This notion raised concerns regarding possible genotoxicities of Que in hematopoietic stem and progenitor cells (HSPCs). However, molecular targets mediating Que effects on DNA repair relevant to MLL translocations have not been defined. In this study we describe novel and potentially genotoxic Que activities in suppressing non-homologous end joining and homologous recombination pathways downstream of MLL cleavage. Using pharmacological dissection of DNA-PK, ATM and PI3K signalling we defined PI3K inhibition by Que with a concomitant decrease in the abundance of key DNA repair genes to be responsible for DNA repair inhibition. Evidence for the downstream TopoII-independent mutagenic potential of Que was obtained by documenting further increased frequencies of MLL rearrangements in human HSPCs concomitantly treated with Etoposide and Que versus single treatments. Importantly, by engaging a tissue engineered placental barrier, we have established the extent of Que transplacental transfer and hence provided the evidence for Que reaching fetal HSPCs. Thus, Que exhibits genotoxic effects in human HSPCs via different mechanisms when applied continuously and at high concentrations. In light of the demonstrated Que transfer to the fetal compartment our findings are key to understanding the mechanisms underlying infant leukemia and provide molecular markers for the development of safety values.

Topics: Adult; Ascorbic Acid; Cell Culture Techniques; Cell Transformation, Neoplastic; Cells, Cultured; Colony-Forming Units Assay; DNA Damage; DNA Repair; DNA Topoisomerases, Type II; Dose-Response Relationship, Drug; Etoposide; Female; Genistein; Hematopoietic Stem Cells; Histone-Lysine N-Methyltransferase; Histones; Humans; Infant; Leukemia; Maternal-Fetal Exchange; Myeloid-Lymphoid Leukemia Protein; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Pregnancy; Quercetin; Signal Transduction; Topoisomerase II Inhibitors

The objective of the present study was to investigate how oxidative status influences the effectiveness of cytotoxicity of artemisinin towards cancer cells. It is hypothesized that antioxidants would reduce, whereas pro-oxidants would enhance, cytotoxicity.. Molt-4 human leukemia cells were incubated with vitamins C, E, D3, dexamethasone, or hydrogen peroxide alone or in combination with dihydroartemisinin (DHA). Concentrations of these compounds studied were similar to those achievable by oral administration. Viable cell counts were performed before (0 h) and at, 24 and 48 h after treatment.. Vitamin C, vitamin D3, dexamethasone, and H2O2 caused significant Molt-4 cell death. Vitamin E caused an increase in Molt-4 cell growth. Vitamin C and vitamin D3 significantly interacted with DHA at the 48-h time point and with H2O2 at both 24-h and 48-h time points.. Cellular oxidative status could alter the potency of artemisinin in killing cancer cells.

Topics: Antioxidants; Apoptosis; Artemisinins; Ascorbic Acid; Cell Line, Tumor; Cholecalciferol; Chromans; Dexamethasone; Humans; Hydrogen Peroxide; Leukemia; Oxidation-Reduction; Reactive Oxygen Species

Epidemiologic studies on diet and leukemia risk have shown inconsistent results. This study examined the associations between dietary factors and the risk of adult leukemia in Chinese populations.. A multicenter case-control study was conducted in southeast and northeast China between 2008 and 2013. It included 442 incident cases with hematologically confirmed leukemia and 442 controls, individually match to cases by gender, birth quinquennium, and study site. Information on diet was sought from face-to-face interviews using a validated and reliable 103-item food frequency questionnaire. Odds ratios (ORs) and confidence intervals (CIs) were estimated by conditional logistic regression.. Vegetables intake was associated with decreased risk of adult leukemia, with a significant dose-response relationship and adjusted OR of 0.30 (95 % CI 0.18-0.50) for the highest versus the lowest quartiles intake. Compared with non-consumers, the adjusted OR was 0.51 (95 % CI 0.29-0.93) for those who consumed milk at the highest tertile. Intakes of fruits, red meat, poultry, and fish were not associated with the risk. Dietary nutrients, including dietary fiber, carotenoids, vitamins B1, B2, and C, niacin, and folate, were significantly associated with reduced risks. Elevated risk was related to dietary intake animal fat and dietary habits with frequent intakes of fat, deep-fried, and smoked foods ( p for trend <0.05).. Our findings suggest that diets rich in vegetables and adequate amount of milk reduce the risk of adult leukemia, whereas diets preferring fat, deep-fried, and smoked foods increase the risk in Chinese populations.

Topics: Adult; Aged; Animals; Ascorbic Acid; Carotenoids; Case-Control Studies; China; Diet; Dietary Fiber; Feeding Behavior; Female; Folic Acid; Food; Humans; Leukemia; Logistic Models; Male; Middle Aged; Niacin; Odds Ratio; Riboflavin; Risk Factors; Surveys and Questionnaires; Thiamine; Vitamins

Potential risk of high-dose vitamin C consumption is often ignored. Recently, gram-dose vitamin C is being intravenously injected for the treatment of cancer, which can expose circulating blood cells to extremely high concentrations of vitamin C. As well as platelets, red blood cells (RBCs) can actively participate in thrombosis through procoagulant activation. Here, we examined the procoagulant and prothrombotic risks associated with the intravenous injection of gram-dose vitamin C. Vitamin C (0.5-5 mM) increased procoagulant activity of freshly isolated human RBCs via the externalization of phosphatidylserine (PS) to outer cellular membrane and the formation of PS-bearing microvesicles. PS exposure was induced by the dysregulation of key enzymes for the maintenance of membrane phospholipid asymmetry, which was from vitamin C-induced oxidative stress, and resultant disruption of calcium and thiol homeostasis. Indeed, the intravenous injection of vitamin C (0.5-1.0 g/kg) in rats in vivo significantly increased thrombosis. Notably, the prothrombotic effects of vitamin C were more prominent in RBCs isolated from cancer patients, who are at increased risks of thrombotic events. Vitamin C-induced procoagulant and prothrombotic activation of RBCs, and increased thrombosis in vivo. RBCs from cancer patients exhibited increased sensitivity to the prothrombotic effects of vitamin C, reflecting that intravenous gram-dose vitamin C therapy needs to be carefully revisited.

Topics: Adenosine Triphosphate; Animals; Ascorbic Acid; Blood Coagulation; Calcium; Erythrocytes; Flow Cytometry; Glutathione; Hemolysis; Humans; Injections, Intravenous; Leukemia; Male; Microscopy, Electron, Scanning; Neoplasms; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Thrombosis; Vitamins

In this work, a photoelectrochemical (PEC) biosensor was fabricated for sensitive and specific detection of microRNA based on Bi2S3 nanorods and enzymatic signal amplification. Using the catalytic effect of alkaline phosphatase on l-ascorbic acid 2-phosphate trisodium salt (AAP), ascorbic acid (AA) was in situ generated and used as electron donor. Based on this, a signal-on protocol was successively achieved for microRNAs detection due to the dependence of photocurrent response on the concentration of electron donor of AA. The results demonstrated that the photocurrent response enhanced with increasing the hybridized concentration of microRNA. Under the amplification of the immunogold labeled streptavidin (SA-AuNPs), a low detection limit of 1.67 fM was obtained. The fabricated biosensor showed good detection stability and specificity, and it could discriminate only one-base mismatched microRNA sequence. Moreover, the down-regulated expression of microRNA-21 in DF-1 chicken fibroblast cells infected with subgroup J avian leukemia virus (ALVs) was confirmed by the developed method, indicating that microRNA-21 might be a new biomarker for avian leukemia. This work opens a different perspective for microRNAs detection and early diagnose of avian leukemia.

Topics: Alkaline Phosphatase; Animals; Ascorbic Acid; Biosensing Techniques; Chickens; Electrons; Leukemia; Limit of Detection; MicroRNAs; Nanotubes

We examined the antileukemic effects of high concentrations of L-ascorbic acid (high AA) on human leukemic cells. In vitro, high AA markedly induced apoptosis in various leukemic cell lines by generating hydrogen peroxide (H2O2) but not in normal hematopoietic stem/progenitor cells. High AA significantly repressed leukemic cell proliferation as well as neoangiogenesis in immunodeficient mice. We then noted that in leukemic cells, HIF-1α transcription was strongly suppressed by high AA and correlated with the transcription of VEGF. Our data indicate that exposure to high AA markedly increased the intracellular AA content of leukemic cells and inhibited the nuclear translocation of NF-κB, which mediates expression of HIF-1α. We next generated K562 cells that overexpressed HIF-1α (K562-HIF1α cells) and assessed the mechanistic relationship between inhibition of HIF-1α transcription and the antileukemic effect of high AA. The ability of high AA to induce apoptosis was significantly lower in K562-HIF1α cells than in K562 cells in vitro. We found that expression of HIF-1α-regulated antiapoptotic proteins of the Bcl-2 family, such as Mcl-1, Bcl-xL, and Bcl-2, was significantly suppressed by high AA in K562 cells, but was sustained at higher levels in K562-HIF1α cells, regardless of high AA exposure. Moreover, repression of cell proliferation and neoangiogenesis by high AA was completely abrogated in mice receiving transplants of K562-HIF1α cells. These results indicate that, along with H2O2 generation, downregulation of HIF-1α transcription plays a crucial role in growth inhibition of human leukemic cells by high AA.

Topics: Animals; Antineoplastic Agents; Ascorbic Acid; Cell Line, Tumor; Cell Proliferation; Disease Models, Animal; Disease Progression; Gene Expression Regulation, Leukemic; Hematopoietic Stem Cells; Humans; Hypoxia-Inducible Factor 1, alpha Subunit; K562 Cells; Leukemia; Mice; Transcription, Genetic; Tumor Burden; Xenograft Model Antitumor Assays

Silver nanoparticles (AgNPs) have anti-cancer effect. However, whether and how these particles could inhibit the growth of acute myeloid leukemia (AML) cells is unclear. In the present study, we prepared AgNPs with various sizes and investigated their cytotoxic effect on AML cells. We found that AgNPs could inhibit the viability of AML cells including the isolates from AML patients. AgNPs caused the production of reactive oxygen species (ROS), losses of mitochondrial membrane potential (MMP), DNA damage and apoptosis. Both vitamin C (Vit C) and N-acetyl-L-cysteine (NAC) could completely reverse the generation of ROS upon AgNPs, however only NAC but not Vit C could protect the cells from losses of MMP, DNA damage and apoptosis thoroughly. Similar results were obtained when cells were treated with silver ions alone. As NAC was not only an antioxidant to scavenge ROS but also a silver ion chelator, these data supported the model that both generation of ROS and release of silver ions played critical roles in the AgNPs-induced cytotoxic effect against AML cells. Taken together, this work elucidated the cytotoxic effect of AgNPs on AML cells and their underlying mechanism and might have significant impact on AML treatment.

Topics: Acetylcysteine; Adolescent; Adult; Aged; Antineoplastic Agents; Antioxidants; Apoptosis; Ascorbic Acid; Cell Line, Tumor; DNA Damage; Female; HL-60 Cells; Humans; Ions; Leukemia; Male; Membrane Potential, Mitochondrial; Metal Nanoparticles; Middle Aged; Reactive Oxygen Species; Silver

Ascorbic acid (AsA) treatment is expected to be a potential cancer therapy strategy with few side-effects that can be used alone or in combination with chemotherapy. However, the combination of AsA, a free radical scavenger, with radiation is not clearly understood; conflicting data are reported for cancer cell death. We conducted this study to determine the effect of AsA treatment combined with X-irradiation and the role of reactive oxygen species (ROS) in HL-60 human promyelocytic leukemia cells. Additive cytotoxic effects were observed when the cells were exposed to 2 Gy X-irradiation after 2.5 mM AsA treatment. When catalase was added to the culture with AsA alone, the cytotoxic effects of AsA disappeared. X-irradiation increased intercellular ROS levels and mitochondrial superoxide levels. By contrast, AsA alone and in combination with X-irradiation decreased ROS levels. However, in the presence of catalase neutralizing H2O2, AsA alone or in combination with X-irradiation only slightly decreased the intercellular ROS. Moreover, AsA decreased the mitochondrial membrane potential, which is commonly associated with apoptosis. These results suggest that the reduction of ROS did not result from ROS scavenging by AsA, and AsA induced apoptosis through a ROS-independent pathway. This study reports that a combination of AsA with radiation treatment is effective in cancer therapy when considering ROS in cancer cells.

Topics: Apoptosis; Ascorbic Acid; Free Radical Scavengers; HL-60 Cells; Humans; Hydrogen Peroxide; Kinetics; Leukemia; Membrane Potential, Mitochondrial; Mitochondria; Reactive Oxygen Species; Superoxide Dismutase; X-Rays

Bioactivity-guided fractionation of extracts of Aglaia loheri Blanco (Meliaceae) yielded a cytotoxic isolate, termed Maldi 531.2[M + H]+. This phenolic ester was further investigated for its in vitro cytotoxicity toward human CCRF-CEM leukemia cells and their multi-drug resistant (MDR) subline, CEM/ADR5000. The intrinsic mitochondrial membrane potential (ΔΨm) and induction of apoptosis by this isolate were evaluated.. Chromatography techniques, mass spectrometry and proton NMR were employed to isolate Maldi 531.2[M + H]+. XTT cell proliferation and viability assay was used for cytotoxic test, and JC-1[5',5',6,6',-tetrachloro-1,1',3,3'-tetraethylbenzimidazoyl carbocyanine iodide was used to assess ΔΨm and initiation of apoptosis; Annexin V/FITC-PI staining was employed to analyse apoptosis.. Maldi 531.2[M + H]+ was cytotoxic towards both CCRF-CEM and CEM/ADR5000 cells with IC50 values of 0.02 and 0.03 μM, respectively. The mitochondrial membrane potential (ΔΨm) of MDR cells was significantly reduced in a dose-dependent manner leading to apoptosis as detected by flow cytometric Annexin V-FITC/ PI staining.. Maldi 531.2[M + H]+ may be a potential anti-cancer drug candidate whose mode of action include reduction of the mitochondrial membrane potential and induction of apoptosis.

Topics: Aglaia; Antineoplastic Agents; Apoptosis; Ascorbic Acid; Cell Line, Tumor; Cell Proliferation; Drug Resistance, Neoplasm; Humans; Leukemia; Membrane Potential, Mitochondrial; Phenols; Plant Extracts

4-(Hydroxyphenyl)retinamide (4-HPR) is a synthetic retinoid with a strong apoptotic effect towards different cancer cell lines in vitro, and it is currently tested in clinical trials. Increases of reactive oxygen species (ROS) and modulation of endogenous sphingolipid levels are well-described events observed upon 4-HPR treatment, but there is still a lack of understanding of their relationship and their contribution to cell death. LC-MS analysis of sphingolipids revealed that in human leukemia CCRF-CEM and Jurkat cells, 4-HPR induced dihydroceramide but not ceramide accumulation even at sublethal concentrations. Myriocin prevented the 4-HPR-induced dihydroceramide accumulation, but it did not prevent the loss of viability and increase of intracellular ROS production. On the other hand, ascorbic acid, Trolox, and vitamin E reversed 4-HPR effects on cell death but not dihydroceramide accumulation. NDGA, described as a lipoxygenase inhibitor, exerted a significantly higher antioxidant activity than vitamin E and abrogated 4-HPR-mediated ROS. It did not however rescue cellular viability. Taken together, this study demonstrates that early changes observed upon 4-HPR treatment, i.e., sphingolipid modulation and ROS production, are mechanistically independent events. Furthermore, the results indicate that 4-HPR-driven cell death may occur even in the absence of dihydroceramide or ROS accumulation. These observations should be taken into account for an improved design of drug combinations.

Topics: Antineoplastic Agents; Antioxidants; Apoptosis; Ascorbic Acid; Cell Line, Tumor; Cell Survival; Ceramides; Fenretinide; Flavanones; Humans; Leukemia; Lipid Peroxidation; Lipoxygenase Inhibitors; Masoprocol; Mitochondria; Oxidative Stress; Oxidoreductases; Reactive Oxygen Species; Sphingolipids; Vitamin E

This study was conducted to examine the utility of the combined use of ascorbic acid (AsA) and radiation in clinical applications. We investigated cell survival, DNA fragmentation, and caspase activation after X-ray irradiation and AsA treatment of human leukemia HL60 cells. The number of living cells decreased after combined X-ray irradiation and AsA treatment (2 Gy + 5 mM) in comparison with that after X-ray irradiation (2 Gy) or AsA treatment (5 mM) alone. DNA fragmentation was more in the cells subjected to combined X-ray irradiation and AsA treatment than in those subjected to X-ray irradiation alone. Caspase-3, caspase-8, and caspase-9 were highly activated following combined X-ray irradiation and AsA treatment, but caspase-8 activity was not markedly increased after X-ray irradiation alone. Bax levels in the mitochondrial membrane fractions were increased after AsA treatment alone and after combined X-ray irradiation and AsA treatment. However, there was no apparent increase in the Bax levels after X-ray irradiation treatment alone. Thus, this study confirmed that supplementing X-ray irradiation with AsA treatment results in increased apoptosis in HL60 cells. With regard to the apoptosis-inducing factors, we hypothesized that Bax and caspase-8 were activated after combined X-ray irradiation and AsA treatment compared with either treatment alone.

Topics: Apoptosis; Ascorbic Acid; bcl-2-Associated X Protein; Caspase 3; Caspase 8; Caspase 9; Cell Line, Tumor; Cell Survival; DNA Fragmentation; HL-60 Cells; Humans; Leukemia; Mitochondria; Time Factors; X-Rays

Leukemia is characterized by uncontrolled marrow cell proliferation and metastatic foci. We investigated the antitumor potential of a nutrient mixture on malignant leukemia P-388 cells.. The nutrient mixture containing lysine, proline, ascorbic acid, green tea extract and other nutrients is formulated to target key pathways in cancer progression. The cells were treated with the mixture, and tested at doses 0, 10, 50, 100, 500 and 1000 μg/ml in triplicates. The effects were evaluated by cell proliferation, Matrigel invasion, cell morphology and apoptosis. The in vivo effect was measured in male nude mice (n = 12) inoculated with P-388 cells. After randomly dividing in two groups, each group was fed regular and the nutrient mixture supplemented diet and the mice were sacrificed after four weeks.. The nutrient mixture decreased P-388 cell proliferation at 500 and 1000 μg/ml. Only 10% cells were viable at 1000 μg/ml. Matrigel invasion was significantly inhibited in a dose dependent manner with virtually total inhibition at 1000 μg/ml. Cell morphological features notably changed with dose increase to 1000 μg/ml. Analysis of apoptotic cells on live green caspase kit exhibited gradual increase with the increasing dose of the nutrient mixture, and at 1000 μg/ ml 92% of P-388 cells were in late apoptosis. Tumors in the group of mice supplemented with the nutrient mixture had 50% lower weight compared to the tumors in control group (p = 0.0105). Histopathologically, both the groups of tumors were similar, yet size of tumors in the group treated with the nutrient mixture was considerably smaller.. These results indicate that the nutrient mixture exhibited significant action against multiple targets in P-388 leukemia and may have potential in human leukemia.

Topics: Animals; Antioxidants; Apoptosis; Ascorbic Acid; Camellia sinensis; Cell Line, Tumor; Cell Proliferation; Collagen; Drug Combinations; Food; Laminin; Leukemia; Lysine; Mice; Mice, Nude; Neoplasm Invasiveness; Plant Extracts; Proline; Proteoglycans

We isolated the 4 kinds of flavonoids from strawberry 'Nohime' and examined the effect of these flavonoids on the degranulation in RBL-2H3 cells. The flavonoids were found to suppress the degranulation from Ag-stimulated RBL-2H3 cells to different extents. To disclose the inhibitory mechanism of degranulation by flavonoids, we examined their effects on the intracellular free Ca(2+) concentration ([Ca(2+)]i) and the intracellular signaling pathway such as Lyn, Syk, and PLCgammas. The intracellular free Ca(2+) concentration ([Ca(2+)]i) was elevated by Fc epsilonRI activation, but these flavonoid treatments reduced the elevation of [Ca(2+)]i by suppressing Ca(2+) influx. Kaempferol strongly suppressed the activation of Syk and PLCgammas. It was thus suggested that suppression of Ag-stimulated degranulation by the flavonoids is mainly due to suppression of [Ca(2+)]i elevation and Syk activation. These results suggested that strawberry would be of some ameliorative benefit for the allergic symptoms.

Topics: Animals; Anti-Allergic Agents; Basophil Degranulation Test; Basophils; beta-N-Acetylhexosaminidases; Calcium; Cell Degranulation; Cell Line, Tumor; Flavonoids; Fragaria; Fruit; Immunoglobulin E; Intracellular Signaling Peptides and Proteins; Leukemia; Molecular Structure; Protein-Tyrosine Kinases; Rats; Reactive Oxygen Species; Receptors, IgE; Signal Transduction; Syk Kinase

4-Hydroxy-2(E)-nonenal (HNE), a reactive aldehyde derived from oxidized lipids, has been implicated in the pathogenesis of cardiovascular and neurological diseases, in part by its ability to induce oxidative stress and by protein carbonylation in target cells. The effects of intracellular ascorbic acid (vitamin C) on HNE-induced cytotoxicity and protein carbonylation were investigated in human THP-1 monocytic leukemia cells. HNE treatment of these cells resulted in apoptosis, necrosis, and protein carbonylation. Ascorbic acid accumulated in the cells at concentrations of 6.4 or 8.9 mM after treatment with 0.1 or 1 mM ascorbate in the medium for 18 h. Pretreatment of cells with 1.0 mM ascorbate decreased HNE-induced formation of reactive oxygen species and formation of protein carbonyls. The protective effects of ascorbate were associated with an increase in the formation of GSH-HNE conjugate and its phase 1 metabolites, measured by LC-MS/MS, and with increased transport of GSH conjugates from the cells into the medium. Ascorbate pretreatment enhanced the efflux of the multidrug resistant protein (MRP) substrate, carboxy-2',7'-dichlorofluorescein (CDF), and it prevented the HNE-induced inhibition of CDF export from THP-1 cells, suggesting that the protective effect of ascorbate against HNE cytotoxicity is through modulation of MRP-mediated transport of GSH-HNE conjugate metabolites. The formation of ascorbate adducts of HNE was observed in the cell exposure experiments, but it represented a minor pathway contributing to the elimination of HNE and to the protective effects of ascorbate.

Topics: Aldehydes; Apoptosis; Ascorbic Acid; Biological Transport; Caspase 3; Fluoresceins; Glutathione; Humans; Inactivation, Metabolic; Leukemia; Protein Carbonylation; Tumor Cells, Cultured

The proliferation and/or survival of a variety of cells is dependent on cellular hydrogen peroxide (H(2)O(2)) production. We tested whether this was true of leukemic cells, using cell lines from leukemic patients (CEM, 697, Mn-60, and Tanoue). We found that addition of catalase inhibited proliferation of all cell lines and induced death in two. However, this turned out to be due to arginase contamination of the catalase. Pure arginase inhibited cell proliferation and survival, which was reversible by adding L-arginine, demonstrating the L-arginine dependency of these cells. The glutathione peroxidase mimetic ebselen killed the cells by a novel, rapid form of death, preceded by cell blebbing and prevented by N-acetylcysteine, suggesting toxicity is not due to ebselen's antioxidant activity. Addition of N-acetylcysteine to remove endogenous H(2)O(2) stimulated survival and proliferation, suggesting that basal levels of H(2)O(2) promoted cell death. Consistent with this, leukemic cell death was induced by adding as little as 5 microM H(2)O(2). Ascorbic acid, even at 100 microM, induced death through H(2)O(2) production. Thus H(2)O(2) does not promote proliferation and survival, rather the opposite, and previous literature may have misinterpreted the effects of antioxidants. Arginase, H(2)O(2), ascorbic acid, and ebselen might be useful in the treatment of leukemia.

Topics: Acetylcysteine; Antioxidants; Arginase; Arginine; Ascorbic Acid; Azoles; Catalase; Cell Death; Cell Line, Tumor; Cell Proliferation; Humans; Hydrogen Peroxide; Isoindoles; Leukemia; Organoselenium Compounds

The pro-oxidant effect of L-ascorbic acid (LAA) is toxic to leukemia cells. LAA induces the oxidation of glutathione to its oxidized form (GSSG) and this is followed by a concentration-dependent H(2)O(2) accumulation, which occurs in parallel to the induction of apoptosis. To identify early protein targets of LAA in leukemia cells, we used a differential proteomics approach in NB4 human leukemia cells treated with 0.5 mM of LAA for 30 min. This exposure was determined to efficiently block cellular proliferation and to activate oxidative stress-inducible apoptosis. We identified nine proteins that sensitively reacted to LAA treatment by using two-dimensional (2-D) gel electrophoresis and matrix-assisted laser desorption ionization time-of-flight-MS. A subunit of protein-disulfide isomerase (a thiol/disulfide exchange catalyst) and immunoglobulin-heavy-chain binding protein (BiP, identical to Hsp70 chaperone) showed quantitative expression profile differences. A myeloid leukemia associated antigen protein (a tropomyosin isoform) showed changes in pI as a result of phosphorylation. Our studies demonstrate for the first time that the addition of LAA to cells results in an immediate change in the intracellular thiol/disulfide condition and that this includes an increase in the GSH oxidation with changes in the superfamily of thiol/disulfide exchange catalysts. These results suggest that LAA oxidizes intracellular reduced glutathione and modulates disulfide bond formation in proteins.

Topics: Apoptosis; Ascorbic Acid; Cell Line, Tumor; Cell Proliferation; Humans; Leukemia; Oxidation-Reduction; Protein Disulfide-Isomerases; Proteome; Proteomics; Tropomyosin

Curcumin (Cur) is a promising antioxidant and anticancer drug, but several recent studies indicate that Cur exerts its anticancer activity through promoting reactive oxygen species (ROS) generation. In the present study, concentration-dependent regulation of Cur on cell proliferation, viability and ROS generation, and effect of water-soluble antioxidants ascorbic acid (ASA), N-acetyl-cysteine (NAC) and reduced glutathione (GSH) on the antioxidant and anticancer activity of Cur were investigated in human myeloid leukemia cells (HL-60 cells). We found that although Cur concentration- and time-dependently decreased the proliferation and viability of cells, its effect on ROS generation (as indicated by the level of malondialdehyde, MDA) varied with its concentrations. I.e., low concentrations of Cur diminished the ROS generation, while high Cur promoted it. Combined with the opposite effect of 50 microM H2O2 on low or high Cur-induced MDA alteration, cell proliferation arrest and cell death, these results proved that low Cur exerted its anticancer activity through diminishing ROS generation in HL-60 cells, while high Cur through promoting ROS generation. Further studies showed that all water-soluble antioxidants ASA, NAC and GSH significantly enhanced both the antioxidant and the anticancer activity of low Cur. Considering that the extra accumulation of ROS is harmful to normal cells, the data presented here indicate that instead of using high doses, combining low doses of Cur with water-soluble antioxidants is a better strategy for us to improve the anticancer activity of Cur.

Topics: Acetylcysteine; Antineoplastic Agents; Antioxidants; Ascorbic Acid; Cell Proliferation; Cell Survival; Curcumin; Glutathione; HL-60 Cells; Humans; Hydrogen Peroxide; Indicators and Reagents; Leukemia; Lipid Peroxidation; Malondialdehyde; Oxidants; Reactive Oxygen Species

Since the higher redox potential of quinone molecules has been correlated with enhanced cellular deleterious effects, we studied the ability of the association of ascorbate with several quinones derivatives (having different redox potentials) to cause cell death in K562 human leukaemia cell line. The rationale is that the reduction of quinone by ascorbate should be dependent of the quinone half-redox potential thus determining if reactive oxygen species (ROS) are formed or not, leading ultimately to cell death or cell survival. Among different ROS that may be formed during redox cycling between ascorbate and the quinone, the use of different antioxidant compounds (mannitol, desferal, N-acetylcysteine, catalase and superoxide dismutase) led to support H2O2 as the main oxidizing agent. We observed that standard redox potentials, oxygen uptake, free ascorbyl radical formation and cell survival were linked. The oxidative stress induced by the mixture of ascorbate and the different quinones decreases cellular contents of ATP and GSH while caspase-3-like activity remains unchanged. Again, we observed that quinones having higher values of half-redox potential provoke a severe depletion of ATP and GSH when they were associated with ascorbate. Such a drop in ATP content may explain the lack of activation of caspase-3. In conclusion, our results indicate that the cytotoxicity of the association quinone/ascorbate on K562 cancer cells may be predicted on the basis of half-redox potentials of quinones.

Topics: Adenosine Triphosphate; Apoptosis; Ascorbic Acid; Caspase 3; Caspases; Cell Line, Tumor; Free Radicals; Glutathione; Humans; Leukemia; Oxidation-Reduction; Oxygen; Quinones; Vitamin K 3

While accumulation of reactive oxygen species (ROS) is believed to be harmful to organisms, recent studies show that quercetin (QU), a promising antioxidant and anticancer drug, exerts its anticancer role through either diminishing or promoting ROS generation under different conditions. In the present study, it was investigated whether the water-soluble antioxidants ascorbic acid (ASA), N-acetyl-cysteine (NAC) and reduced glutathione (GSH) can enhance both the antioxidant and anticancer activity of quercetin in human myeloid leukemia cells (HL-60 cells). Proliferation, viability and ROS accumulation (indicated by the level of malondialdehyde, MDA) was significantly decreased by QU in HL-60 cells. 50 microM H2O2 markedly attenuated the antioxidant and anticancer activity of QU, proving that diminution of ROS accumulation considerably contributes to the QU-induced decrease of HL-60 cells proliferation and viability. When the effects of water-soluble antioxidants were tested, ASA at 1 mM, NAC at 500 microM, or GSH at 250 microM significantly enhanced QU-mediated proliferation arrest, cell death and ROS diminution. These results indicate that certain amounts of ROS are critical for the proliferation and viability of HL-60 cells, while water-soluble antioxidants enhance the anticancer activity of QU through scavenging ROS. Combing QU with water-soluble antioxidants could be a useful strategy to improve the anticancer activity of QU by increasing its antioxidant activity.

Topics: Acetylcysteine; Antineoplastic Agents; Antioxidants; Ascorbic Acid; Cell Proliferation; Cell Survival; Glutathione; HL-60 Cells; Humans; Hydrogen Peroxide; Indicators and Reagents; Leukemia; Lipid Peroxidation; Malondialdehyde; Quercetin; Reactive Oxygen Species; Solubility

We investigated peroxide and superoxide accumulation, cytochrome c nature and release from mitochondria, as well as caspase activation during exposure of HL-60 cells to H(2)O(2) and the protective effect of ascorbic acid. Exposure of the cells to 100 microM H(2)O(2) resulted in intracellular accumulation of peroxides, denaturation of cytochrome c that was identified in the mitochondria and cytosol, release of native cytochrome c to the cytosol and fall in mitochondrial membrane potential (DeltaPsi(m)). Loading of cells with ascorbic acid before exposure to H(2)O(2) resulted in a dose-dependent protective effect against: intracellular accumulation of peroxides, DeltaPsi(m) alteration, cytochrome c denaturation and release. The accumulation of peroxides induced processings and activations of procaspase-8, -9 and -3. Double staining with antiserum which recognizes the p18 subunit of cleaved caspase-3 and with Hoechst had shown that a high percentage of cells exposed to 100 microM H(2)O(2) stained positively with the antibody and showed features of apoptosis. Ascorbic acid loading prevented caspase activation induced by H(2)O(2). We conclude that ascorbic acid protects against activation of apoptotic cascades in HL-60 cells exposed to H(2)O(2) and against apoptosis.

Topics: Apoptosis; Ascorbic Acid; Caspase 3; Caspases; Cytochrome c Group; Drug Interactions; Enzyme Activation; HL-60 Cells; Humans; Hydrogen Peroxide; Immunoblotting; Leukemia; Membrane Potentials; Mitochondria; Protective Agents; Protein Denaturation; Superoxides; Tumor Cells, Cultured

Ascorbate is an important cofactor in many cellular metabolic reactions and is intimately linked to iron homeostasis. Continuously cultured cells are ascorbate deficient due to the lability of the vitamin in solution and to the fact that daily supplementation of media with ascorbate is unusual. We found that ascorbate repletion alone did not alter ferritin synthesis. However, ascorbate-replete human hepatoma cells, Hep3B and HepG2, as well as K562 human leukemia cells achieved a substantially higher cellular ferritin content in response to a challenge with iron than did their ascorbate-deficient counterparts grown under standard culture conditions. Most of the elevation in ferritin content was due to an increase in de novo ferritin synthesis of greater than 50-fold, as shown by in vivo labeling with [35S]methionine and immunoprecipitation. RNA-blot analysis showed only minor changes in steady state levels of ferritin mRNA, suggesting that ascorbate enhances iron-induced ferritin synthesis primarily by post-transcriptional events. Transient gene expression experiments using chloramphenicol acetyltransferase reporter gene constructs showed that the ascorbate effect on ferritin translation is not mediated through the stem-loop near the translational start site that transduces ferritin synthesis in response to cytokines. The data suggest that ascorbate possibly modifies the action of the iron-responsive element on ferritin translation, although more precise structure-function studies are needed to clarify this issue. These data demonstrate a novel role of ascorbate as a signaling molecule in post-transcriptional gene regulation. The mechanism by which ascorbate modulates cellular iron metabolism is complex and requires additional detailed investigation.

Topics: Ascorbic Acid; Carcinoma, Hepatocellular; Ferritins; Humans; Iron; Leukemia; Protein Biosynthesis; RNA, Messenger; Tumor Cells, Cultured

The relation between the intake of certain food items thought to be precursors or inhibitors of N-nitroso compounds (NOC) and risk of leukemia was investigated in a case-control study among children from birth to age 10 years in Los Angeles County, California (United States). Cases were ascertained through a population-based tumor registry from 1980 to 1987. Controls were drawn from friends and by random-digit dialing. Interviews were obtained from 232 cases and 232 controls. Food items of principal interest were: breakfast meats (bacon, sausage, ham); luncheon meats (salami, pastrami, lunch meat, corned beef, bologna); hot dogs; oranges and orange juice; and grapefruit and grapefruit juice. We also asked about intake of apples and apple juice, regular and charcoal broiled meats, milk, coffee, and coke or cola drinks. Usual consumption frequencies were determined for both parents and the child. When the risks were adjusted for each other and other risk factors, the only persistent significant associations were for children's intake of hot dogs (odds ratio [OR] = 9.5, 95 percent confidence interval [CI] = 1.6-57.6 for 12 or more hot dogs per month, trend P = 0.01), and fathers' intake of hot dogs (OR = 11.0, CI = 1.2-98.7 for highest intake category, trend P = 0.01). There was no evidence that fruit intake provided protection. While these results are compatible with the experimental animal literature and the hypothesis that human NOC intake is associated with leukemia risk, given potential biases in the data, further study of this hypothesis with more focused and comprehensive epidemiologic studies is warranted.

Topics: Animals; Ascorbic Acid; Carbonated Beverages; Case-Control Studies; Cattle; Child; Child, Preschool; Fathers; Feeding Behavior; Female; Humans; Infant; Infant, Newborn; Leukemia; Los Angeles; Male; Meat; Meat Products; Nitroso Compounds; Risk Factors; Swine

Etoposide (VP-16) is an antitumor drug currently in use for the treatment of a number of human cancers. Mechanisms of VP-16 cytotoxicity involve DNA breakage secondary to inhibition of DNA topoisomerase II and/or direct drug-induced DNA strand cleavage. The VP-16 molecule contains a hindered phenolic group which is crucial for its antitumor activity because its oxidation yields reactive metabolites (quinones) capable of irreversible binding to macromolecular targets. VP-16 phenoxyl radical is an essential intermediate in VP-16 oxidative activation and can be either converted to oxidation products or reduced by intracellular reductants to its initial phenolic form. In the present paper we demonstrate that the tyrosinase-induced VP-16 phenoxyl radical could be reduced by ascorbate, glutathione (GSH) and dihydrolipoic acid. These reductants caused a transient disappearance of a characteristic VP-16 phenoxyl radical ESR signal which reappeared after depletion of the reductant. The reductants completely prevented VP-16 oxidation by tyrosinase during the lag-period as measured by high performance liquid chromatography; after the lag-period VP-16 oxidation proceeded with the rate observed in the absence of reductants. In homogenates of human K562 leukemic cells, the tyrosinase-induced VP-16 phenoxyl radical ESR signal could be observed only after a lag-period whose duration was dependent on cell concentration; VP-16 oxidation proceeded in cell homogenates after this lag-period. In homogenates of isolated nuclei, the VP-16 phenoxyl radical and VP-16 oxidation were also detected after a lag-period, which was significantly shorter than that observed for an equivalent amount of cells. In both cell homogenates and in nuclear homogenates, the duration of the lag period could be increased by exogenously added reductants. The duration of the lag-period for the appearance of the VP-16 phenoxyl radical signal in the ESR spectrum can be used as a convenient measure of cellular reductive capacity. Interaction of the VP-16 phenoxyl radical with intracellular reductants may be critical for its metabolic activation and cytotoxic effects.

Topics: Ascorbic Acid; Cell Nucleus; Chromatography, High Pressure Liquid; Deferoxamine; Electron Spin Resonance Spectroscopy; Etoposide; Free Radicals; Glutathione; Humans; Leukemia; Monophenol Monooxygenase; Oxidation-Reduction; Phenols; Thioctic Acid; Tumor Cells, Cultured

A transmembrane monodehydroascorbate reductase activity with a high affinity in the subpicomolar concentration range of the free radical can be measured at the surface of erythroleukemic cells using a ferricyanide-driven redox cycle. The activity is dependent on the membrane potential and can therefore only be found in intact cells. It is independent of the glutathione content of the cells. Thenoyltrifluoroacetone is an efficient inhibitor of the activity, whereas ouabain, monensin and tetraethylammonium show no effect. Cells are able to generate ascorbate from dehydroascorbic acid. This explains why both forms of vitamin C show practically the same affinity for the redox cycle but why it does not drive the redox cycle by itself because it is much slower and is not inhibited by thenoyltrifluoroacetone. The reductase activity is independent of the degree of differentiation of the leukemic cells.

Topics: Animals; Ascorbic Acid; Cell Differentiation; Cell Membrane; Dehydroascorbic Acid; Ferricyanides; Hemin; Leukemia; Membrane Potentials; Monensin; Ouabain; Oxidation-Reduction; Oxidoreductases; Tetraethylammonium; Tetraethylammonium Compounds; Tumor Cells, Cultured

L-Ascorbic acid (LAA) was shown to modulate the in vitro growth of colonies of human and mouse myeloma progenitor-stem cells through use of a unique cell-culture assay. LAA was also shown to modulate the in vitro growth of leukemic colony-forming cells (L-CFC) from bone marrow of patients with acute myelocytic leukemia. LAA enhanced the growth of L-CFC in 35% of patients and suppressed the growth of L-CFC in 15% of patients. The minimum effective concentration was 0.03 mmol/L. The modulating effect is specific to LAA because other redox compounds are without effect. From the cell kinetic standpoint, the LAA effect is cytostatic rather than cytocidal. Similar LAA effects have prognostic value in patients with myelodysplastic syndromes (MDS), with LAA-sensitive patients displaying shorter survival than LAA-insensitive patients. MDS appears to be the ideal disease for clinical trials involving in vivo LAA manipulation to control the disease process.

Topics: Adult; Ascorbic Acid; Bone Marrow; Cell Division; Humans; Leukemia; Multiple Myeloma; Myelodysplastic Syndromes; Osmolar Concentration; Preleukemia; Prognosis; Stem Cells

The effect of methylglyoxal (MG), ascorbic acid and lactaldehyde has been tested on the in vitro respiration of Ehrlich ascites carcinoma (EAC) cells and several normal and malignant human tissues. Methylglyoxal inhibited the respiration of each type of malignant cell and tissue tested, but it had practically no inhibitory effect on the respiration of any of the normal cells and tissues. Ascorbic acid exhibited a synergistic effect with MG in inhibiting the respiration of all the neoplastic cells. In the presence of lactaldehyde, a catabolite of MG, the inhibitory effect of MG on the respiration of tumor cells was significantly reduced. Lactaldehyde can exert a similar protective effect on the loss of viability and transplantability of MG-treated EAC cells.

Topics: Aldehydes; Animals; Ascorbic Acid; Carcinoma, Ehrlich Tumor; Cell Survival; Female; Humans; In Vitro Techniques; Leukemia; Mice; Neoplasms; Oxygen Consumption; Pyruvaldehyde; Uterus

Vitamin C was shown to be an essential requirement for the growth of mouse myeloma cells in an in vitro colony assay. Human leukemia (acute nonlymphocytic leukemia) cell colonies grow well in a similar in vitro culture system, and vitamin C has been shown to enhance the growth of leukemic cell colonies in 77 (35%) of 219 leukemic patients while none of 34 normal bone marrows tested simultaneously shows growth enhancement by this vitamin. This vitamin C effect is reproducible in repeated experiments in same patients, specific to this vitamin, selective for leukemic cells, and is proven to be biological in nature. Further, leukemic cells are mobilized back and forth between cycling and resting states with vitamin C supplementation/depletion. Our more recent study indicates that the preleukemia (myelodysplastic syndrome), generally known to be related to acute nonlymphocytic leukemia, has similar pattern in terms of vitamin C sensitivity, with 8 of 25 patients (32%) showing the growth enhancement with this vitamin.

Topics: Ascorbic Acid; Bone Marrow; Cell Division; Humans; Leukemia; Myelodysplastic Syndromes; Tumor Cells, Cultured

The effects of L-ascorbic acid (LAA) on the in vitro growth of human leukemic colony-forming cells (L-CFC) were analyzed for all acute nonlymphocytic leukemia patients from whom bone marrow aspirates were received by this laboratory for cell culture study. Among 259 cases, 163 could be directly evaluated for LAA effect. L-CFC growth enhancement was noted in 53 (33%) and suppression in 28 (17%), with overall 50% of patients affected by LAA. Among 34 normal bone marrows tested, none were enhanced by LAA while 8 (24%) were suppressed. While caution is needed in interpreting L-CFC suppression by LAA, L-CFC enhancement is clearly significant. Two isomers of LAA, D-isoascorbic acid and D-ascorbic acid, which have weaker antiscorbutic activity than that of LAA, also produced the L-CFC growth-enhancing effect, but to a lesser degree than that of LAA. A dose-response study also substantiated that D-ascorbic acid was definitely less effective than was LAA. Since D-ascorbic acid is the true optical isomer of LAA and has identical physicochemical properties as does LAA, this differential effect is clearly of biological nature. This study indicates that L-CFC growth suppression by LAA is observed in one-sixth of leukemic patients, L-CFC enhancement in one-third of patients, and that L-CFC growth enhancement is a clearly significant finding with a biological mechanism as the basis.

Topics: Ascorbic Acid; Bone Marrow; Cells, Cultured; Humans; Leukemia; Neoplastic Stem Cells; Stem Cells; Stereoisomerism

The effect of L-ascorbic acid (LAA) on the in vitro colony growth of leukemic cells from the marrows of patients with acute nonlymphocytic leukemia was studied using a modified agar culture method featuring daily feeding. In 10 of 31 patients (32%) the growth was enhanced with supplementation of LAA in culture. The average number of colonies was reduced to 26% if LAA was deleted from culture. This growth enhancing effect appears to be specific to LAA: neither glutathione which has redox potential similar to LAA nor the acidification of culture medium with HCI to the pH of medium containing LAA is effective. This effect is also selective for leukemic marrows, and normal marrow colonies are not affected over wide range of LAA concentrations (0 to 300 microM) which are achievable in human in vivo.

Topics: Ascorbic Acid; Cell Culture Techniques; Cell Proliferation; Glutathione; Humans; Leukemia; Oxidation-Reduction; Tumor Cells, Cultured; Vitamins

The suppressive effect of L-ascorbic acid on the growth of bone marrow cells from patients with acute nonlymphocytic leukemia was studied using a modified agar culture method featuring daily feeding to allow the growth of leukemic cell colonies. In seven of 28 patients (25%), the numbers of leukemic cell colonies grown in culture were reduced to 21% of control by the addition of L-ascorbic acid (0.3 mM) to the culture medium. Glutathione did not suppress leukemic cell colonies although it has a similar oxidation-reduction potential to that of L-ascorbic acid. The addition of L-ascorbic acid reduced the pH of the medium. However, a comparable reduction of pH by the addition of HCl did not suppress leukemic cell colonies. In simultaneous cultures for leukemic and normal marrow cells, the suppression of leukemic cell colony was noted with a concentration of L-ascorbic acid as low as 0.1 mM (a concentration achievable in vivo), but normal myeloid colonies were not suppressed until the concentration of L-ascorbic acid reached an extremely high level (1 mM). In conclusion, growth of leukemic cells in culture was suppressed by L-ascorbic acid in a substantial proportion of patients with acute nonlymphocytic leukemia. This suppression was a specific effect of L-ascorbic acid and was not due to its oxidation-reduction potential or pH change. Leukemic cells were selectively affected at an L-ascorbic acid concentration attainable in vivo while normal hemopoietic cells were not suppressed.

Topics: Adult; Aged; Ascorbic Acid; Bone Marrow; Cell Division; Colony-Forming Units Assay; Female; Hematopoietic Stem Cells; Humans; In Vitro Techniques; Leukemia; Leukemia, Erythroblastic, Acute; Leukemia, Myeloid, Acute; Male; Middle Aged

Despite similar levels and duration of benzene exposure, toxicological responses of workers are highly variable. Given a similar degree of exposure, why do some workers remain apparently unaffected, while others develop alterations of the hemopoietic system? It is hypothesized that inadequate nutritional status of possibly several nutrients including iron, selenium, methionine and ascorbic acid may enhance susceptibility to adverse effects caused by benzene.

Topics: Animals; Ascorbic Acid; Benzene; Dietary Fats; Dietary Proteins; Dogs; Energy Metabolism; Humans; Iron; Leukemia; Methionine; Nutritional Physiological Phenomena; Selenium; Vitamin B Complex

The interaction between lyophilized samples of ascorbic acid and Cu2+, Fe3+ or Mn2+ has been investigated by means of ESR spectroscopy. All of the three transition metal ions form complexes with vitamin C, but only in the case of Cu2+ and Fe3+ the interaction results in a reduction of the metal ions. Cu2+ and ascorbic acid seem to form 2 : 1 complexes with an equilibrium constant of about K = 1 X 10(7) mol-1. None of these metal ion complexes exhibits, however, the ESR spectrum obtained with leukemic blood.

Topics: Ascorbic Acid; Copper; Electron Spin Resonance Spectroscopy; Erythrocyte Membrane; Humans; Iron; Leukemia; Manganese; Metalloproteins; Molecular Conformation

The interaction between lyophilized samples of ascorbic acid and some copper proteins (ceruloplasmin, cytochrome-c-oxidase, ascorbate-oxidase) has been investigated by means of ESR spectroscopy. The spectra obtained are identical to the one obtained with leukemic blood. The consequences of this for the molecular events occurring in cancer are discussed. The model proposed can explain the experimental findings reported thus far (such as change in spin concentration with the development of cancer, the presence of a high concentration of antioxidants etc.) as well as reconsile the two existing and seemingly contradictory hypothesis. Possible implications for lipid peroxidation and for the respiratory process are discussed.

Topics: Ascorbate Oxidase; Ascorbic Acid; Ceruloplasmin; Copper; Electron Spin Resonance Spectroscopy; Electron Transport Complex IV; Erythrocytes; Humans; Leukemia; Metalloproteins; Oxidation-Reduction

Topics: Ascorbic Acid; Copper; Electron Spin Resonance Spectroscopy; Erythrocytes; Humans; Leukemia; Leukocytes

The effect of ascorbic acid on white ghosts of erythrocytes and plasma has been investigated by means of ESR spectroscopy. Since the spectra obtained are identical to the one obtained with leukemic blood it is concluded that the receptor for vitamin C has to be searched for in membrane and plasma as well. Determination of Cu and Fe by means of atomic absorption spectroscopy revealed that both of the metals are also present in the membrane. In the case of copper, it must exist there as a protein which has not been identified yet. Oxidizing substances, such as KMnO4, reverse the effect produced by ascorbic acid.

Topics: Ascorbic Acid; Copper; Electron Spin Resonance Spectroscopy; Erythrocyte Membrane; Erythrocytes; Humans; Iron; Leukemia; Spectrophotometry, Atomic

Thirty five cows and heifers, all positive reactors on ID test and all showing persistent lymphocytosis (15 with markedly enlarged lymphatic glands) were divided in 4 experimental groups and treated with P-2, a new antiviral agent, previously shown to be effective for several RNA type viruses. In table are indicated groups, range of dosages of P-2, and variability in WBC and lymphocyte. White blood cells found to be at the lowest level (P less than 0.02) one month after treatment with P-2, a less marked reduction (P less than 0.05) was found when the experiments ended at 7 months. A significant (P less than 0.05) fall in lymphocytes was found one month after treatment but this was not significant at the end of experiment. In 12 animals with lymphosarcomatous disease significant retraction of lymphatic glands. It is not clear whether the sudden drop in WBC and lymphocytes is due to the virostatic effect of drug or an effect of drug per se. New series of experiments will be made to treat BLV with two agents: one virostatic and other cytostatic.

Topics: Animals; Antiviral Agents; Ascorbic Acid; Cattle; Cattle Diseases; Female; Formaldehyde; Leukemia; Leukemia Virus, Bovine; Polymers

Topics: Ascorbic Acid; Humans; Leukemia; Leukocytes

Topics: Adolescent; Adult; Alcohol Oxidoreductases; Ascorbic Acid; Busulfan; Carboxy-Lyases; Child, Preschool; Esterases; Female; Glucuronates; Humans; Ketones; Leukemia; Leukemia, Myeloid; Leukocytes; Male; Middle Aged; Pyrophosphatases; Sugar Acids; Uridine Diphosphate Sugars; Uronic Acids; Xylitol

The platelet ascorbic acid concentration was measured in 26 normal subjects and found to be 20 times as high as in plasma. This is in agreement with previous reports in the literature. The platelets of patients with uraemia, leukaemia, and megaloblastic anaemia had a lower than normal platelet ascorbic acid content. In uraemia and megaloblastic anaemia the plasma ascorbic acid concentration was normal suggesting that a platelet defect may be responsible for the low platelet ascorbic acid content. In leukaemia the low platelet ascorbic acid content is probably secondary to a low plasma level.

Topics: Acute Disease; Adolescent; Adult; Anemia, Macrocytic; Ascorbic Acid; Blood Platelet Disorders; Blood Platelets; Female; Humans; Leukemia; Leukemia, Lymphoid; Leukemia, Myeloid; Male; Plasma; Uremia

Topics: Animals; Ascorbic Acid; Aspartate Aminotransferases; Cattle; Cattle Diseases; Diagnosis, Differential; Leukemia; Magnesium

Topics: Absorption; Animals; Ascorbic Acid; Bone Marrow; Histocytochemistry; Leukemia; Leukocytes; Liver; Microscopy, Electron; Rats; Spleen

Topics: Adrenocorticotropic Hormone; Anemia; Anemia, Myelophthisic; Anti-Bacterial Agents; Ascorbic Acid; Benzene; Biopsy; Blood Transfusion; Cortisone; Female; Hematologic Diseases; Hematology; Leukemia; Liver Extracts; Mortality; Occupational Diseases; Pathology; Poisoning; Prednisolone; Prednisone; Pregnancy; Pregnancy Complications; Pregnancy Complications, Hematologic; Tetracycline; Toxicology; Vasopressins; Vitamin B 12

Topics: Ascorbic Acid; Blood Platelets; Humans; Leukemia; Leukocytes; Plasma

Topics: Animals; Ascorbic Acid; Folic Acid Antagonists; Leukemia; Leukemia, Experimental; Methotrexate; Mice; Vitamins

Topics: Ascorbic Acid; Leukemia; Mechlorethamine; Neoplasms; Nitrogen Mustard Compounds; Vitamin A

Topics: Ascorbic Acid; Humans; Leukemia; Vitamins

Topics: Administration, Oral; Aniline Compounds; Ascorbic Acid; Chalcones; Coloring Agents; Flavonoids; Hemophilia A; Hesperidin; Hypoprothrombinemias; Leukemia; Prothrombin; Purpura; Purpura, Thrombocytopenic; Tolonium Chloride; Vitamins

Topics: Arylsulfonates; Ascorbic Acid; Blood; Humans; Leukemia; Vitamins

Topics: Animals; Ascorbic Acid; Leukemia; Leukemia, Experimental; Leukemia, Lymphoid; Lymphatic Vessels; Organic Chemicals; Vitamins

Topics: Ascorbic Acid; Humans; Leukemia; Leukemia, Myeloid; Liver Cirrhosis; Liver Cirrhosis, Alcoholic; Polycythemia Vera; Vitamin A; Vitamins

Topics: Adrenal Cortex Hormones; Ascorbic Acid; Chronic Disease; Desoxycorticosterone Acetate; Leukemia; Vitamins