Deferasirox is a powerful NF-kappaB inhibitor in myelodysplastic cells and in leukemia cell lines acting independently from cell iron deprivation by chelation and reactive oxygen species scavenging

Fluvastatin suppresses hemin-induced cell death, reactive oxygen species generation, and elevated labile iron pool

BACKGROUND

In transfusion-related iron overload, macrophage/reticuloendothelial cells are the first site of haem-derived iron accumulation. The prevention of haem-induced cytotoxicity in macrophages may represent a target for iron overload treatment. Deferasirox, an oral iron chelator, has been used to treat transfusion-related iron overload however, low adherence to the therapy is an issue. Statins, which are widely used for the prevention of atherosclerotic cardiovascular diseases, also have anti-oxidative and anti-inflammatory effects independent of their lipid lowering ones. Whether statins can suppress hemin-induced cytotoxicity and enhance the cytoprotective effects of deferasirox are important considerations to improve transfusion-related iron overload treatment. This study also evaluated the effects of eltrombopag, a thrombopoietin receptor agonist.

MATERIALS AND METHODS

Human monocytic THP-1 cells were pretreated with statins, deferasirox, and/or eltrombopag, followed by treatment with hemin. Cell viability, reactive oxygen species generation, and the intracellular labile iron pool were measured using flow cytometry.

RESULTS

Fluvastatin and another four statins suppressed hemin-induced cell death, reactive oxygen species generation, and increases in the labile iron pool. Moreover, fluvastatin enhanced the suppressive effect of deferasirox on hemin-induced cell death. The effects of eltrombopag were similar to those of the statins.

CONCLUSION

The safety of statins is well established. When used in combination with fluvastatin or other statins, the suppressive effects of deferasirox on hemin-induced cytotoxicity in THP-1 cells were amplified. Further research is necessary to see whether statins will act in the same way in vivo or in human primary monocytes/macrophages.

Deferasirox, an iron chelator, impacts myeloid differentiation by modulating NF-kB activity via mitochondrial ROS

The iron chelator deferasirox (DFX) is effective in the treatment of iron overload. In certain patients with myelodysplastic syndrome, DFX can also provide a dramatic therapeutic benefit, improving red blood cell production and decreasing transfusion requirements. Nuclear Factor-kappa B (NF-kB) signalling has been implicated as a potential mechanism behind this phenomenon, with studies focusing on the effect of DFX on haematopoietic progenitors. Here, we examine the phenotypic and transcriptional effects of DFX throughout myeloid cell maturation in both murine and human model systems. The effect of DFX depends on the stage of differentiation, with effects on mitochondrial reactive oxygen species (ROS) production and NF-kB pathway regulation that vary between progenitors and neutrophils. DFX triggers a greater increase in mitochondrial ROS production in neutrophils and this phenomenon is mitigated when cells are cultured in hypoxic conditions. Single-cell transcriptomic profiling revealed that DFX decreases the expression of NF-kB and MYC (c-Myc) targets in progenitors and decreases the expression of PU.1 (SPI1) gene targets in neutrophils. Together, these data suggest a role of DFX in impairing terminal maturation of band neutrophils.

COVID-19 and β-thalassemia: in lieu of evidence and vague nexus

Coronavirus disease 19 (COVID-19) is an infectious disease caused by severe acute respiratory coronavirus 2 (SARS-CoV-2) causing acute systemic disorders and multi-organ damage. β-thalassemia (β-T) is an autosomal recessive disorder leading to the development of anemia. β-T may lead to complications such as immunological disorders, iron overload, oxidative stress, and endocrinopathy. β-T and associated complications may increase the risk of SARS-CoV-2, as inflammatory disturbances and oxidative stress disorders are linked with COVID-19. Therefore, the objective of the present review was to elucidate the potential link between β-T and COVID-19 regarding the underlying comorbidities. The present review showed that most of the β-T patients with COVID-19 revealed mild to moderate clinical features, and β-T may not be linked with Covid-19 severity. Though patients with transfusion-dependent β-T (TDT) develop less COVID-19 severity compared to non-transfusion-depend β-T(NTDT), preclinical and clinical studies are recommended in this regard.

Therapeutic potential of iron chelators in retinal vascular diseases

Iron is one of the necessary metal elements in the human body. There are numerous factors that control the balance of iron metabolism, and its storage and transportation mechanisms are intricate. As one of the most energy-intensive tissues in the body, the retina is susceptible to iron imbalance. The occurrence of iron overload in the retina leads to the generation of a significant quantity of reactive oxygen species. This will aggravate local oxidative stress and inflammatory reactions and even lead to ferroptosis, eventually resulting in retinal dysfunction. The blood-retina-retinal barrier is eventually harmed by oxidative stress and elevated inflammation, which are characteristics of retinal vascular disorders. The pathophysiology of retinal vascular disorders may be significantly influenced by iron. Recently, iron-chelating agents have been found to have antioxidative and anti-inflammatory actions in addition to iron chelating. Therefore, iron neutralization is considered to be a new and potentially useful therapeutic strategy. This article reviews the iron overload in retinal vascular diseases and discusses the therapeutic potential of iron-chelating agents.

Identification and overcoming rituximab resistance in diffuse large B-cell lymphoma using next-generation sequencing

BACKGROUND/AIMS

Although rituximab, an antiCD20 monoclonal antibody, has dramatically improved the clinical outcomes of diffuse large B-cell lymphoma, rituximab resistance remains a challenge.

METHODS

We developed a rituximab-resistant cell line (RRCL) by sequential exposure to gradually increasing concentrations of rituximab in a rituximab-sensitive cell line (RSCL). When the same dose of rituximab was administered, RRCL showed a smaller decrease in cell viability and apoptosis than RSCL. To determine the differences in gene expression between RSCL and RRCL, we performed next-generation sequencing.

RESULTS

In total, 1,879 differentially expressed genes were identified, and in the over-representation analysis of Consensus-PathDB, mitogen-activated protein kinase (MAPK) signaling pathway showed statistical significance. MAPK13, which encodes the p38δ protein, was expressed more than four-fold in RRCL. Western blot analysis revealed that phosphop38 expression mainwas increased in RRCL, and when p38 inhibitor was administered, phosphop38 expression was significantly decreased. Therefore, we hypothesized that p38 MAPK activation was associated with rituximab resistance. Previous studies have suggested that p38 is associated with NF-κB activation. Deferasirox has been reported to inhibit NF-κB activity and suppress phosphorylation of the MAPK pathway. Furthermore, it also has cytotoxic effects on various cancers and synergistic effects in overcoming drug resistance. In this study, we confirmed that deferasirox induced dose-dependent cytotoxicity in both RSCL and RRCL, and the combination of deferasirox and rituximab showed a synergistic effect in RRCL at all combination concentrations.

CONCLUSION

We suggest that p38 MAPK, especially p38δ, activation is associated with rituximab resistance, and deferasirox may be a candidate to overcome rituximab resistance.

Puzzling Out Iron Complications in Cancer Drug Resistance

Iron metabolism are frequently disrupted in cancer. Patients with cancer are prone to anemia and receive transfusions frequently; the condition which results in iron overload, contributing to serious therapeutic complications. Iron is introduced as a carcinogen that may increase tumor growth. However, investigations regarding its impact on response to chemotherapy, particularly the induction of drug resistance are still limited. Here, iron contribution to cell signaling and various molecular mechanisms underlying iron-mediated drug resistance are described. A dual role of this vital element in cancer treatment is also addressed. On one hand, the need to administer iron chelators to surmount iron overload and improve the sensitivity of tumor cells to chemotherapy is discussed. On the other hand, the necessary application of iron as a therapeutic option by iron-oxide nanoparticles or ferroptosis inducers is explained. Authors hope that this paper can help unravel the clinical complications related to iron in cancer therapy.

Iron chelator deferasirox inhibits NF-κB activity in hepatoma cells and changes sorafenib-induced programmed cell deaths

OBJECTIVE

The improvements of antitumor effects and tolerability on chemotherapy for advanced hepatocellular carcinoma (HCC) are warranted. Here, we aimed to elucidate the mechanism of the combining effect of tyrosine kinase inhibitor sorafenib (SOR) and iron chelator deferasirox (DFX) in human hepatoma cell lines, HepG2 and Huh-7.

METHODS

The types of programmed cell deaths (PCDs); necrosis/necroptosis and apoptosis, were evaluated by flow cytometry and fluorescent microscopy. Human cleaved caspase-3 was analyzed by ELISA for apoptosis. GSH assay was used for ferroptosis. PCDs inhibition was analyzed by adding apoptosis inhibitor Z-VAD-FMK, ferroptosis inhibitor ferrostatin-1, necroptosis inhibitor necrosulfonamide, respectively. The expression of NF-κB was quantified by Western blotting.

RESULTS

In SOR monotherapy, cleaved caspase-3 expression was increased in all concentrations, confirming the result that SOR induces apoptosis. In SOR monotherapy, GSH/GSSG ratio was decreased on concentration-dependent, showing that SOR also induced ferroptosis. Lipid Peroxidation caused by SOR, corresponding to ferroptosis, was suppressed by DFX. In fluorescence microscopy of SOR monotherapy, apoptosis was observed at a constant rate on all concentrations, while necroptosis and ferroptosis were increased on high concentration. In sorafenib and deferasirox combinations, sub G1 phase increased additively. In SOR and DFX combinations, the cytotoxic effects were not suppressed by ferrostatin-1, but suppressed by Z-VAD-FMK and necrosulfonamide. In each monotherapy, and SOR + DFX combinations, the expression of NF-κB in nucleus was suppressed. Regarding PCD by SOR and DFX combination, ferroptosis was suppressed and both apoptosis and necroptosis became dominant.

CONCLUSION

Suppression of NF-κB is possibly involved in the effect of DFX. As a result, SOR and DFX combination showed additive antitumor effects for HCC through the mechanism of programed cell deaths and NF-kB signal modification.

Iron Overload and Breast Cancer: Iron Chelation as a Potential Therapeutic Approach

Breast cancer has historically been one of the leading causes of death for women worldwide. As of 2020, breast cancer was reported to have overtaken lung cancer as the most common type of cancer globally, representing an estimated 11.3% of all cancer diagnoses. A multidisciplinary approach is taken for the diagnosis and treatment of breast cancer that includes conventional and targeted treatments. However, current therapeutic approaches to treating breast cancer have limitations, necessitating the search for new treatment options. Cancer cells require adequate iron for their continuous and rapid proliferation. Excess iron saturates the iron-binding capacity of transferrin, resulting in non-transferrin-bound iron (NTBI) that can catalyze free-radical reactions and may lead to oxidant-mediated breast carcinogenesis. Moreover, excess iron and the disruption of iron metabolism by local estrogen in the breast leads to the generation of reactive oxygen species (ROS). Therefore, iron concentration reduction using an iron chelator can be a novel therapeutic strategy for countering breast cancer development and progression. This review focuses on the use of iron chelators to deplete iron levels in tumor cells, specifically in the breast, thereby preventing the generation of free radicals. The inhibition of DNA synthesis and promotion of cancer cell apoptosis are the targets of breast cancer treatment, which can be achieved by restricting the iron environment in the body. We hypothesize that the usage of iron chelators has the therapeutic potential to control intracellular iron levels and inhibit the breast tumor growth. In clinical settings, iron chelators can be used to reduce cancer cell growth and thus reduce the morbidity and mortality in breast cancer patients.

Anti-Inflammatory Effects of the Iron Chelator, DIBI, in Experimental Acute Lung Injury

Iron plays a critical role in the immune response to inflammation and infection due to its role in the catalysis of reactive oxygen species (ROS) through the Haber-Weiss and Fenton reactions. However, ROS overproduction can be harmful and damage healthy cells. Therefore, iron chelation represents an innovative pharmacological approach to limit excess ROS formation and the related pro-inflammatory mediator cascades. The present study was designed to investigate the impact of the iron chelator, DIBI, in an experimental model of LPS-induced acute lung injury (ALI). DIBI was administered intraperitoneally in the early and later stages of lung inflammation as determined by histopathological evaluation. We found that lung tissues showed significant injury, as well as increased NF-κB p65 activation and significantly elevated levels of various inflammatory mediators (LIX, CXCL2, CCL5, CXCL10, IL-1𝛽, IL-6) 4 h post ALI induction by LPS. Mice treated with DIBI (80 mg/kg) in the early stages (0 to 2 h) after LPS administration demonstrated a significant reduction of the histopathological damage score, reduced levels of NF-κB p65 activation, and reduced levels of inflammatory mediators. Intravital microscopy of the pulmonary microcirculation also showed a reduced number of adhering leukocytes and improved capillary perfusion with DIBI administration. Our findings support the conclusion that the iron chelator, DIBI, has beneficial anti-inflammatory effects in experimental ALI.

Understanding the Potential and Risk of Bacterial Siderophores in Cancer

Siderophores are iron chelating molecules produced by nearly all organisms, most notably by bacteria, to efficiently sequester the limited iron that is available in the environment. Siderophores are an essential component of mammalian iron homeostasis and the ongoing interspecies competition for iron. Bacteria produce a broad repertoire of siderophores with a canonical role in iron chelation and the capacity to perform versatile functions such as interacting with other microbes and the host immune system. Siderophores are a vast area of untapped potential in the field of cancer research because cancer cells demand increased iron concentrations to sustain rapid proliferation. Studies investigating siderophores as therapeutics in cancer generally focused on the role of a few siderophores as iron chelators; however, these studies are limited and some show conflicting results. Moreover, siderophores are biologically conserved, structurally diverse molecules that perform additional functions related to iron chelation. Siderophores also have a role in inflammation due to their iron acquisition and chelation properties. These diverse functions may contribute to both risks and benefits as therapeutic agents in cancer. The potential of siderophore-mediated iron and bacterial modulation to be used in the treatment of cancer warrants further investigation. This review discusses the wide range of bacterial siderophore functions and their utilization in cancer treatment to further expand their functional relevance in cancer detection and treatment.

Prognostic Factors and Clinical Considerations for Iron Chelation Therapy in Myelodysplastic Syndrome Patients

Iron chelation therapy (ICT) is an important tool in the treatment of transfusion-dependent lower-risk myelodysplastic syndrome (MDS) patients. ICT is effective in decreasing iron overload and consequently in limiting its detrimental effects on several organs, such as the heart, liver, and endocrine glands. Besides this effect, ICT also proved to be effective in improving peripheral cytopenia in a significant number of MDS patients, thus further increasing the clinical interest of this therapeutic tool. In the first part of the review, we will analyze the toxic effect of iron overload and its mechanism. Subsequently, we will revise the clinical role of ICT in various subsets of MDS patients (low, intermediate, and high risk MDS, patients who are candidates for allogeneic stem cell transplantation).

Iron and platelets: A subtle, under-recognized relationship

The role of iron in the formation and functioning of erythrocytes, and to a lesser degree of white blood cells, is well established, but the relationship between iron and platelets is less documented. Physiologically, iron plays an important role in hematopoiesis, including thrombopoiesis; iron levels direct, together with genetic factors, the lineage commitment of megakaryocytic/erythroid progenitors toward either megakaryocyte or erythroid progenitors. Megakaryocytic iron contributes to cellular machinery, especially energy production in platelet mitochondria. Thrombocytosis, possibly favoring vascular thrombosis, is a classical feature observed with abnormally low total body iron stores (mainly due to blood losses or decreased duodenal iron intake), but thrombocytopenia can also occur in severe iron deficiency anemia. Iron sequestration, as seen in inflammatory conditions, can be associated with early thrombocytopenia due to platelet consumption and followed by reactive replenishment of the platelet pool with possibility of thrombocytosis. Iron overload of genetic origin (hemochromatosis), despite expected mitochondrial damage related to ferroptosis, has not been reported to cause thrombocytopenia (except in case of high degree of hepatic fibrosis), and iron-related alteration of platelet function is still a matter of debate. In acquired iron overload (of transfusional and/or dyserythropoiesis origin), quantitative or qualitative platelet changes are difficult to attribute to iron alone due to the interference of the underlying hematological conditions; likewise, hematological improvement, including increased blood platelet counts, observed under iron oral chelation is likely to reflect mechanisms other than the sole beneficial impact of iron depletion.

Eltrombopag and its iron chelating properties in pediatric acute myeloid leukemia

Pediatric acute myeloid leukemia (AML) represents 20% of total childhood leukemia diagnoses and is characterized by poor prognosis with a long-term survival rate around the 50%, when patients are properly treated. The standard treatment for pediatric AML currently consists in a combination of cytarabine (Ara-C) and antracycline. Iron plays an important role in cancer development and progression. Targeting iron and its metabolism mediators could be a novel therapeutic strategy in cancer.Deferasirox (DFX) inhibits cancer cell proliferation and its use as an antiblastic drug could be suggested. Eltrombopag (ELT), a thrombopoietin receptor agonist used in immunethrombocytopenia, shows anticancer properties related to its emerging iron chelating properties. We compare the anticancer effect of classically used cytarabine with DFX and ELT effects in a pediatric AML cell line, THP-1, in order to identify innovative and more effective therapeutic strategies. ELT and DFX reduce intracellular iron concentration by inhibiting its uptake and by promoting its release. In particular, even though further investigations are needed to better understand the extact underlying action mechanisms, we demonstrated that ELT improves cytarabine antineoplastic activity in pediatric AML cell line.

On-demand treatment with the iron chelator deferasirox is ineffective in preventing blood-induced joint damage in haemophilic mice

INTRODUCTION

Early intervention in the devastating process of haemophilic arthropathy (HA) is highly desirable, but no disease-modifying therapy is currently available. Considering the pivotal role of iron in the development of HA, iron chelation is considered a promising therapeutic approach. A previous study in haemophilic mice demonstrated that treatment with the iron chelator deferasirox (DFX) 8 weeks before joint bleed induction, attenuated cartilage damage upon blood exposure. However, in haemophilia patients this approach is not opportune given the unpredictable occurrence of hemarthroses.

AIM

To evaluate the effectiveness of on-demand DFX treatment, initiated immediately after joint bleed induction.

METHODS

A joint bleed was induced in 66 factor VIII-deficient mice by infra-patellar needle puncture. Mice were randomly assigned to treatment with either placebo (drinking water) or DFX (dissolved in drinking water) throughout the study. Five weeks after joint bleed induction, inflammation and cartilage damage were assessed histologically. Joints of ten bleed naive haemophilic mice served as controls.

RESULTS

A joint bleed resulted in significant inflammation and cartilage damage in the blood-exposed joint compared with those of control animals, in both the placebo and DFX group (all p = <.05). No differences in tibiofemoral or patellar inflammation (p = .305 and p = .787, respectively) nor cartilage damage (p = .265 and p = .802, respectively) were found between the blood-exposed joints of both treatment groups.

CONCLUSION

On-demand treatment with DFX does not prevent joint damage following blood exposure in haemophilic mice. DFX seems unable to reach the joint in time to exert its effect before the irreversible harmful process is initiated.

Iron overload-induced oxidative stress in myelodysplastic syndromes and its cellular sequelae

The myelodysplastic syndromes (MDS) are clonal hematopoietic stem cell disorders. MDS patients often require red blood cell transfusions, resulting in iron overload (IOL). IOL increases production of reactive oxygen species (ROS), oxygen free radicals. We review and illustrate how IOL-induced ROS influence cellular activities relevant to MDS pathophysiology. ROS damage lipids, nucleic acids in mitochondrial and nuclear DNA, structural proteins, transcription factors and enzymes. Cellular consequences include decreased metabolism and tissue and organ dysfunction. In hematopoietic stem cells (HSC), consequences of ROS include decreased glycolysis, shifting the cell from anaerobic to aerobic metabolism and causing HSC to exit the quiescent state, leading to HSC exhaustion or senescence. ROS oxidizes DNA bases, resulting in accumulation of mutations. Membrane oxidation alters fluidity and permeability. In summary, evidence indicates that IOL-induced ROS alters cellular signaling pathways resulting in toxicity to organs and hematopoietic cells, in keeping with adverse clinical outcomes in MDS.

The effects of secondary iron overload and iron chelation on a radiation-induced acute myeloid leukemia mouse model

BACKGROUND

Patients with myelodysplastic syndrome (MDS) require chronic red blood cell (RBC) transfusion due to anemia. Multiple RBC transfusions cause secondary iron overload and subsequent excessive generation of reactive oxygen species (ROS), which leads to mutations, cell death, organ failure, and inferior disease outcomes. We hypothesize that iron loading promotes AML development by increasing oxidative stress and disrupting important signaling pathways in the bone marrow cells (BMCs). Conversely, iron chelation therapy (ICT) may reduce AML risk by lowering iron burden in the iron-loaded animals.

METHODS

We utilized a radiation-induced acute myeloid leukemia (RI-AML) animal model. Iron overload was introduced via intraperitoneal injection of iron dextran, and iron chelation via oral gavage of deferasirox. A total of 86 irradiated B6D2F1 mice with various levels of iron burden were monitored for leukemia development over a period of 70 weeks. The Kaplan-Meier estimator was utilized to assess AML free survival. In addition, a second cohort of 30 mice was assigned for early analysis at 5 and 7 months post-irradiation. The BMCs of the early cohort were assessed for alterations of signaling pathways, DNA damage response and gene expression. Statistical significance was established using Student's t-test or ANOVA.

RESULTS

Iron loading in irradiated B6D2F1 mice accelerated RI-AML development. However, there was a progressive decrease in AML risk for irradiated mice with increase in iron burden from 7.5 to 15 to 30 mg. In addition, ICT decreased AML incidence in the 7.5 mg iron-loaded irradiated mice, while AML onset was earlier for the 30 mg iron-loaded irradiated mice that received ICT. Furthermore, analysis of BMCs from irradiated mice at earlier intervals revealed accelerated dysregulation of signaling pathways upon iron loading, while ICT partially mitigated the effects.

CONCLUSIONS

We concluded that iron is a promoter of leukemogenesis in vivo up to a peak iron dose, but further iron loading decreases AML risk by increasing cell death. ICT can partially mitigate the adverse effects of iron overload, and to maximize its benefit this intervention should be undertaken prior to the development of extreme iron overload.

Deferasirox, an iron-chelating agent, alleviates acute lung inflammation by inhibiting neutrophil activation and extracellular trap formation

OBJECTIVE

Reactive oxygen species (ROS) production by neutrophils induces pulmonary endothelial cell damage and results in acute lung injury (ALI). We previously reported that deferasirox (DFS), an iron-chelating agent, inhibits the ROS production and neutrophil extracellular trap (NET) formation induced by phorbol myristate acetate and formylmethionylleucylphenylalanine in vitro. In the present study, we investigated the effects of DFS in vivo using a mouse model of lipopolysaccharide (LPS)-induced ALI.

METHODS

After DFS administration for 7 days, ALI was induced in mice by LPS via intratracheal administration.

RESULTS

LPS treatment induced neutrophil invasion in the lung tissues, along with NET formation and a significant increase in the quantity of double-stranded DNA in the bronchoalveolar lavage fluid, while pre-administered DFS inhibited these phenomena. However, alteration of neutrophil morphology in the cytoplasm in terms of shape and vacuolization was not inhibited by the pre-administration of DFS, possibly through ROS production.

CONCLUSIONS

DFS suppressed neutrophil invasion into lung tissues and reduced the double-stranded DNA content released by the neutrophils. These results suggest that DFS can potentially be used to prevent diseases related to neutrophil activation including ALI, thrombosis, and vascular endothelial dysfunction.

Modulation of the Immune Response by Deferasirox in Myelodysplastic Syndrome Patients

Deferasirox (DFX) is an oral iron chelator used to reduce iron overload (IO) caused by frequent blood cell transfusions in anemic myelodysplastic syndrome (MDS) patients. To study the molecular mechanisms by which DFX improves outcome in MDS, we analyzed the global gene expression in untreated MDS patients and those who were given DFX treatment. The gene expression profiles of bone marrow CD34⁺ cells were assessed by whole-genome microarrays. Initially, differentially expressed genes (DEGs) were determined between patients with normal ferritin levels and those with IO to address the effect of excessive iron on cellular pathways. These DEGs were annotated to Gene Ontology terms associated with cell cycle, apoptosis, adaptive immune response and protein folding and were enriched in cancer-related pathways. The deregulation of multiple cancer pathways in iron-overloaded patients suggests that IO is a cofactor favoring the progression of MDS. The DEGs between patients with IO and those treated with DFX were involved predominantly in biological processes related to the immune response and inflammation. These data indicate DFX modulates the immune response mainly via neutrophil-related genes. Suppression of negative regulators of blood cell differentiation essential for cell maturation and upregulation of heme metabolism observed in DFX-treated patients may contribute to the hematopoietic improvement.

Effects of Iron Chelation in Osteosarcoma

BACKGROUND

Osteosarcoma is an aggressive bone tumor. It represents the principal cause of cancer-associated death in children. Considering the recent findings on the role of iron in cancer, iron chelation has been investigated for its antineoplastic properties in many tumors. Deferasirox is the most used iron chelator compound and in previous studies showed an anticancer effect in hematologic and solid malignancies. Eltrombopag is a Thrombopoietin receptor used in thrombocytopenia that also binds and mobilize iron. It demonstrated an effect on iron overload conditions and also in contrasting cancer cell proliferation.

OBJECTIVE

We analyzed the effects of deferasirox and eltrombopag in human osteosarcoma cells in an attempt to identify other therapeutic approaches for this tumor.

METHODS

We cultured and treated with deferasirox and Eltrombopag, alone and in combination, two human osteosarcoma cell lines, MG63 and 143B. After 72h exposure, we performed RTqPCR, Western Blotting, Iron Assay and cytofluorimetric assays to evaluate the effect on viability, apoptosis, cell cycle progression and ROS production.

RESULTS

The iron-chelating properties of the two compounds are also confirmed in osteosarcoma, but we did not observe any direct effect on tumor progression.

DISCUSSION

We tested deferasirox and eltrombopag, alone and in combination, in human osteosarcoma cells for the first time and demonstrated that their iron-chelating activity does not influence biochemical pathways related to cancer progression and maintenance.

CONCLUSION

Although further investigations on possible effects mediated by cells of the tumor microenvironment could be of great interest, in vitro iron chelation in osteosarcoma does not impair tumor progression.

Protein Carbonylation and Lipid Peroxidation in Hematological Malignancies

Among the different mechanisms involved in oxidative stress, protein carbonylation and lipid peroxidation are both important modifications associated with the pathogenesis of several diseases, including cancer. Hematopoietic cells are particularly vulnerable to oxidative damage, as the excessive production of reactive oxygen species and associated lipid peroxidation suppress self-renewal and induce DNA damage and genomic instability, which can trigger malignancy. A richer understanding of the clinical effects of oxidative stress might improve the prognosis of these diseases and inform therapeutic strategies. The most common protein carbonylation and lipid peroxidation compounds, including hydroxynonenal, malondialdehyde, and advanced oxidation protein products, have been investigated for their potential effect on hematopoietic cells in several studies. In this review, we focus on the most important protein carbonylation and lipid peroxidation biomarkers in hematological malignancies, their role in disease development, and potential treatment implications.

Deferasirox-Dependent Iron Chelation Enhances Mitochondrial Dysfunction and Restores p53 Signaling by Stabilization of p53 Family Members in Leukemic Cells

Iron is crucial to satisfy several mitochondrial functions including energy metabolism and oxidative phosphorylation. Patients affected by Myelodysplastic Syndromes (MDS) and acute myeloid leukemia (AML) are frequently characterized by iron overload (IOL), due to continuous red blood cell (RBC) transfusions. This event impacts the overall survival (OS) and it is associated with increased mortality in lower-risk MDS patients. Accordingly, the oral iron chelator Deferasirox (DFX) has been reported to improve the OS and delay leukemic transformation. However, the molecular players and the biological mechanisms laying behind remain currently mostly undefined. The aim of this study has been to investigate the potential anti-leukemic effect of DFX, by functionally and molecularly analyzing its effects in three different leukemia cell lines, harboring or not p53 mutations, and in human primary cells derived from 15 MDS/AML patients. Our findings indicated that DFX can lead to apoptosis, impairment of cell growth only in a context of IOL, and can induce a significant alteration of mitochondria network, with a sharp reduction in mitochondrial activity. Moreover, through a remarkable reduction of Murine Double Minute 2 (MDM2), known to regulate the stability of p53 and p73 proteins, we observed an enhancement of p53 transcriptional activity after DFX. Interestingly, this iron depletion-triggered signaling is enabled by p73, in the absence of p53, or in the presence of a p53 mutant form. In conclusion, we propose a mechanism by which the increased p53 family transcriptional activity and protein stability could explain the potential benefits of iron chelation therapy in terms of improving OS and delaying leukemic transformation.

Iron Metabolism in Ferroptosis

Ferroptosis is a form of regulated cell death that is characterized by iron-dependent oxidative damage and subsequent plasma membrane ruptures and the release of damage-associated molecular patterns. Due to the role of iron in mediating the production of reactive oxygen species and enzyme activity in lipid peroxidation, ferroptosis is strictly controlled by regulators involved in many aspects of iron metabolism, such as iron uptake, storage, utilization, and efflux. Translational and transcriptional regulation of iron homeostasis provide an integrated network to determine the sensitivity of ferroptosis. Impaired ferroptosis is implicated in various iron-related pathological conditions or diseases, such as cancer, neurodegenerative diseases, and ischemia-reperfusion injury. Understanding the molecular mechanisms underlying the regulation of iron metabolism during ferroptosis may provide effective strategies for the treatment of ferroptosis-associated diseases. Indeed, iron chelators effectively prevent the occurrence of ferroptosis, which may provide new approaches for the treatment of iron-related disorders. In this review, we summarize recent advances in the theoretical modeling of iron-dependent ferroptosis, and highlight the therapeutic implications of iron chelators in diseases.

Phospholipase C beta1 (PI-PLCbeta1)/Cyclin D3/protein kinase C (PKC) alpha signaling modulation during iron-induced oxidative stress in myelodysplastic syndromes (MDS)

MDS are characterized by anemia and transfusion requirements. Transfused patients frequently show iron overload that negatively affects hematopoiesis. Iron chelation therapy can be effective in these MDS cases, but the molecular consequences of this treatment need to be further investigated. That is why we studied the molecular features of iron effect and Deferasirox therapy on PI-PLCbeta1 inositide signaling, using hematopoietic cells and MDS samples. At baseline, MDS patients showing a positive response after iron chelation therapy displayed higher levels of PI-PLCbeta1/Cyclin D3/PKCalpha expression. During treatment, these responder patients, as well as hematopoietic cells treated with FeCl₃ and Deferasirox, showed a specific reduction of PI-PLCbeta1/Cyclin D3/PKCalpha expression, indicating that this signaling pathway is targeted by Deferasirox. The treatment was also able to specifically decrease the production of ROS. This effect correlated with a reduction of IL-1A and IL-2, as well as Akt/mTOR phosphorylation. In contrast, cells exposed only to FeCl₃ and cells from MDS patients refractory to Deferasirox showed a specific increase of ROS and PI-PLCbeta1/Cyclin D3/PKCalpha expression. All in all, our data show that PI-PLCbeta1 signaling is a target for iron-induced oxidative stress and suggest that baseline PI-PLCbeta1 quantification could predict iron chelation therapy response in MDS.

From Iron Chelation to Overload as a Therapeutic Strategy to Induce Ferroptosis in Leukemic Cells

Despite its crucial importance in numerous physiological processes, iron also causes oxidative stress and damage which can promote the growth and proliferation of leukemic cells. Iron metabolism is strictly regulated and the related therapeutic approaches to date have been to restrict iron availability to tumor cells. However, since a new form of iron-catalyzed cell death has been described, termed ferroptosis, and subsequently better understood, iron excess is thought to represent an opportunity to selectively kill leukemic cells and spare normal hematopoietic cells, based on their differential iron needs. This review summarizes the physiology of iron metabolism and its deregulation in leukemia, the known ferrotoposis pathways, and therapeutic strategies to target the altered iron metabolism in leukemia for the purposes of initiating ferroptosis in these cancer cells.

Myelodysplastic syndromes: a review of therapeutic progress over the past 10 years

INTRODUCTION

Myelodysplastic syndromes (MDS) represent a range of bone marrow disorders, with patients affected by cytopenias and risk of progression to AML. There are limited therapeutic options available for patients, including hypomethylating agents (azacitidine/decitabine), growth factor support, lenalidomide, and allogeneic stem cell transplant.

AREAS COVERED

This review provides an overview of the progress made over the past decade for emerging therapies for lower- and higher-risk MDS (MDS-HR). We also cover advances in prognostication, supportive care, and use of allogeneic SCT in MDS.

EXPERT OPINION

While there have been no FDA-approved therapies for MDS in the past decade, we anticipate the approval of luspatercept based on results from the MEDALIST trial for patients with lower-risk MDS (MDS-LR) and ringed sideroblasts who have failed or are ineligible for erythropoiesis stimulating agents (ESAs). With growing knowledge of the biologic and molecular mechanisms underlying MDS, it is anticipated that new therapies will be approved in the coming years.

Controversies on the Consequences of Iron Overload and Chelation in MDS

Many patients with MDS are prone to develop systemic and tissue iron overload in part as a consequence of disease-immanent ineffective erythropoiesis. However, chronic red blood cell transfusions, which are part of the supportive care regimen to correct anemia, are the major source of iron overload in MDS. Increased systemic iron levels eventually lead to the saturation of the physiological systemic iron carrier transferrin and the occurrence of non-transferrin-bound iron (NTBI) together with its reactive fraction, the labile plasma iron (LPI). NTBI/LPI-mediated toxicity and tissue iron overload may exert multiple detrimental effects that contribute to the pathogenesis, complications and eventually evolution of MDS. Until recently, the evidence supporting the use of iron chelation in MDS was based on anecdotal reports, uncontrolled clinical trials or prospective registries. Despite not fully conclusive, these and more recent studies, including the TELESTO trial, unravel an overall adverse action of iron overload and therapeutic benefit of chelation, ranging from improved hematological outcome, reduced transfusion dependence and superior survival of iron-loaded MDS patients. The still limited and somehow controversial experimental and clinical data available from preclinical studies and randomized trials highlight the need for further investigation to fully elucidate the mechanisms underlying the pathological impact of iron overload-mediated toxicity as well as the effect of classic and novel iron restriction approaches in MDS. This review aims at providing an overview of the current clinical and translational debated landscape about the consequences of iron overload and chelation in the setting of MDS.

Iron protects childhood acute lymphoblastic leukemia cells from methotrexate cytotoxicity

Drug resistance is a fundamental clinical concern in pediatric acute lymphoblastic leukemia (pALL), and methotrexate (MTX) is an essential chemotherapy drug administered for the treatment. In the current study, the effect of iron in response to methotrexate and its underlying mechanisms were investigated in pALL cells. CCRF-CEM and Nalm6 cell lines were selected as T and B-ALL subtypes. Cells were pretreated with ferric ammonium citrate, exposed to the IC50 concentration of MTX and cell viability was assessed using MTT, colony formation, and flow cytometry assays. Iron-loaded cells were strongly resistant to MTX cytotoxicity. The inhibitory effect of N-acetyl cysteine to reverse the acquired MTX resistance was greater than that of the iron chelator, deferasirox, highlighting the importance of iron-mediated ROS in MTX resistance. Subsequently, the upregulation of BCL2, SOD2, NRF2, and MRP1 was confirmed using quantitative RT-PCR. Moreover, a positive correlation was demonstrated between the MRP1 expression levels and bone marrow iron storage in pALL patients. Further supporting our findings were the hematoxylin and eosin-stained histological sections showing that iron-treated nude mice xenografts demonstrated significantly more liver damage than those unexposed to iron. Overall, iron is introduced as a player with a novel role contributing to methotrexate resistance in pALL. Our findings suggest that the patients' bone marrow iron stores are necessary to be assessed during the chemotherapy, and transfusions should be carefully administrated.

Efficacy and safety of iron chelator for transfusion-dependent patients with myelodysplastic syndrome: a meta-analysis

To systematically evaluate the efficacy and safety of iron chelators for transfusion-dependent patients with MDS. Thirteen cohort studies with 12,990 patients diagnosed with MDS were included in this study. According to m eta-analysis results transfusion-dependent MDS patients with secondary iron overload had a longer (HR = 0.52, 95%CI = 0.43-0.62, P < 0.001). Further subgroup analysis revealed a longer LFS (HR = 0.84, 95%CI = 0.76-0.93, P = 0.001) in MDS patients receiving iron chelators than in MDS patients not receiving iron chelators (HR = 0.52, 95%CI = 0.43-0.62, P < 0.001) and in patients with lower-risk MDS (HR = 0.50, 95%CI = 0.43-0.59, P < 0.001). Subgroup analysis of DFX showed that compared with patients not treated with iron chelators, the group receiving DFX monotherapy had significantly increased OS (HR = 0.43, 95%CI = 0.27-0.69, P < 0.001). In terms of tolerance, meta-analysis of binary variables in CAEs indicated that the occurrence of CAEs was significantly reduced by ICT (RR = 0.64, 95%CI = 0.57-0.71, P < 0.001).

Iron and leukemia: new insights for future treatments

Iron, an indispensable element for life, is involved in all kinds of important physiological activities. Iron promotes cell growth and proliferation, but it also causes oxidative stress damage. The body has a strict regulation mechanism of iron metabolism due to its potential toxicity. As a cancer of the bone marrow and blood cells, leukemia threatens human health seriously. Current studies suggest that dysregulation of iron metabolism and subsequent accumulation of excess iron are closely associated with the occurrence and progress of leukemia. Specifically, excess iron promotes the development of leukemia due to the pro-oxidative nature of iron and its damaging effects on DNA. On the other hand, leukemia cells acquire large amounts of iron to maintain rapid growth and proliferation. Therefore, targeting iron metabolism may provide new insights for approaches to the treatment of leukemia. This review summarizes physiologic iron metabolism, alternations of iron metabolism in leukemia and therapeutic opportunities of targeting the altered iron metabolism in leukemia, with a focus on acute leukemia.

Iron chelation by deferasirox confers protection against concanavalin A-induced liver fibrosis: A mechanistic approach

Hepatic iron overload is one of the causative factors for chronic liver injury and fibrosis. The present study aimed to investigate the potential antifibrotic effect of the iron chelator; deferasirox (DFX) in experimentally-induced liver fibrosis in rats. Male Sprague-Dawley rats were administered concanavalin A (Con A) and/or DFX for 6 consecutive weeks. Con A injection induced significant hepatotoxicity as was evident by the elevated transaminases activity, and decreased albumin level. Also, it disturbed the iron homeostasis through increasing C/EBP homologous protein (CHOP), decreasing phosphorylated cAMP responsive element binding protein(P-CREB) and hepcidin levels leading to significant serum and hepatic iron overload. In addition, it induced an imbalance in the oxidative status of the liver via upregulating NADPH oxidase 4 (NOX4), together with a marked decrease in anti-oxidant enzymes' activities. As a consequence, upregulation of nuclear factor-kappa b (NF-κB) and the downstream inflammatory mediators was observed. Those events all together precipitated in initiation of liver fibrosis as confirmed by the elevation of alpha-smooth muscle actin (α-SMA) and liver collagen content. Co-treatment with DFX protected against experimentally-induced liver fibrosis in rats via its iron chelating, anti-oxidant, and anti-inflammatory properties. These findings imply that DFX can attenuate the progression of liver fibrosis.

Iron Compounds as Anticancer Agents

Many ferrocene complexes have been prepared for their oncological potential. Some derive from molecules with known biological effects (taxanes, podophyllotoxine, artemisine, SAHA, etc.) while others are synthetic molecules selected for their cytotoxic effects (N-alkylaminoferrocenes and ferrocenyl alkylpyridinium). Although these complexes have received a great deal of attention, the field of iron metallodrugs is not limited to them. A number of inorganic complexes of iron(ii) and iron(iii) with possible anticancer effects have also been published, although research into their biological effects is often only at an early stage. This chapter also includes iron chelators, molecules that are administered in non-metallic form but whose cytotoxic species are their coordination complexes of iron generated in vivo. The most emblematic molecule of this family is bleomycin, used as an anticancer agent in many chemotherapies. To these can be added the iron chelates originally synthesized to treat iron overload, some of which have been shown to possess interesting anticancer properties. They have been, and continue to be, the subject of many clinical trials, whether alone or in combination. Thus, the area of iron metallodrugs includes molecules with very different structures and reactivity, studied from a number of different perspectives, but focused on increasing the number of molecules at our disposal for combatting cancer.

Iron removal enhances vitamin C-induced apoptosis and growth inhibition of K-562 leukemic cells

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 (H₂O₂) generated by VC. Here we demonstrated that EEI diminished the inhibitory effect of VC on the survival of K562 human leukemic cells in vitro, by reducing the amount of H₂O₂ and abrogating the apoptosis pathways induced by VC. In vivo, in the presence of EEI, the growth inhibitory effect of VC on K562 cells was completely abrogated; in fact, VC enhanced K562 cell growth. Reduction of EEI restored the apoptosis-inducing effect of VC in vitro and enhanced the growth inhibitory effect of VC in vivo. Further studies are warranted to investigate whether the combination of VC and iron depletion has similar effects in various other leukemic or cancer cells against which VC has been effective in previous experimental studies.

Iron in the Tumor Microenvironment-Connecting the Dots

Iron metabolism and tumor biology are intimately linked. Iron facilitates the production of oxygen radicals, which may either result in iron-induced cell death, ferroptosis, or contribute to mutagenicity and malignant transformation. Once transformed, malignant cells require high amounts of iron for proliferation. In addition, iron has multiple regulatory effects on the immune system, thus affecting tumor surveillance by immune cells. For these reasons, inconsiderate iron supplementation in cancer patients has the potential of worsening disease course and outcome. On the other hand, chronic immune activation in the setting of malignancy alters systemic iron homeostasis and directs iron fluxes into myeloid cells. While this response aims at withdrawing iron from tumor cells, it may impair the effector functions of tumor-associated macrophages and will result in iron-restricted erythropoiesis and the development of anemia, subsequently. This review summarizes our current knowledge of the interconnections of iron homeostasis with cancer biology, discusses current clinical controversies in the treatment of anemia of cancer and focuses on the potential roles of iron in the solid tumor microenvironment, also speculating on yet unknown molecular mechanisms.

Deferasirox selectively induces cell death in the clinically relevant population of leukemic CD34+CD38- cells through iron chelation, induction of ROS, and inhibition of HIF1α expression

Despite a high remission rate after therapy, only 40-50% of acute myeloid leukemia (AML) patients survive 5 years after diagnosis. The main cause of treatment failure is thought to be insufficient eradication of CD34⁺CD38^- AML cells. In order to induce preferential cell death in CD34⁺CD38^- AML cells, two separate events may be necessary: (1) inhibition of survival signals such as nuclear factor kappa-beta (NF-κB) and (2) induction of stress responses such as the oxidative stress response. Therefore, regimens that mediate both effects may be favorable. Deferasirox is a rationally designed oral iron chelator mainly used to reduce chronic iron overload in patients who receive long-term blood transfusions. Our study revealed that clinically relevant concentrations of deferasirox are cytotoxic in vitro to AML progenitor cells, but even more potent against the more primitive CD34⁺CD38^- cell population. In addition, we found that deferasirox exerts its effect, at least in part, by inhibiting the NF-κB/hypoxia-induced factor 1-alpha (HIF1α) pathway and by elevating reactive oxygen species levels. We believe that, pending further characterization, deferasirox can be considered as a potential therapeutic agent for eradicating CD34⁺CD38^- AML cells.

Iron overload in myelodysplastic syndromes: Evidence based guidelines from the Canadian consortium on MDS

In 2008 the first evidence-based Canadian consensus guideline addressing the diagnosis, monitoring and management of transfusional iron overload in patients with myelodysplastic syndromes (MDS) was published. The Canadian Consortium on MDS, comprised of hematologists from across Canada with a clinical and academic interest in MDS, reconvened to update these guidelines. A literature search was updated in 2017; topics reviewed include mechanisms of iron overload induced cellular damage, evidence for clinical endpoints impacted by iron overload including organ dysfunction, infections, marrow failure, overall survival, acute myeloid leukemia progression, and endpoints around hematopoietic stem-cell transplant. Evidence for an impact of iron reduction on the same endpoints is discussed, guidelines are updated, and areas identified where evidence is suboptimal. The guidelines address common questions around the diagnosis, workup and management of iron overload in clinical practice, and take the approach of who, when, why and how to treat iron overload in MDS. Practical recommendations for treatment and monitoring are made. Evidence levels and grading of recommendations are provided for all clinical endpoints examined.

Ferritin level changes and erythroid improvement in a group of adult polytransfused patients treated with Deferasirox

Background and aims

Chelating agents therapy is recommended for polytransfused patients that have evidence of iron overload (an elevated serum ferritin or received over 20 units of red blood cell transfusions). Deferasirox showed efficacy and safety in maintaining or reducing body iron. Iron chelation therapy was associated with hematopoiesis improvement in transfusion-dependent patients.Our objectives were to analyze differences in ferritin level in adult polytransfused patients treated with Deferasirox, to estimate the erythroid improvement and variation of the number of red blood cell transfusion after introducing Deferasirox, to evaluate the side effects of the treatment.

Methods

Retrospective study including all the adult polytransfused patients treated with Deferasirox in Hematology Departments of three county hospitals in the North-West of Romania.

Results

We included 40 polytransfused patients treated with Deferasirox in standard doses. There was a significant reduction in serum ferritine from baseline for all the patients (Friedman test, χ2(2)=26.82, p<0.001). Safety profile of Deferasirox was good (three digestive side effects). RBCT were administered before (mean 2.43±1.09 units/month) and after starting Deferasirox (mean 1.40±0.97 units/month), the difference is statistically significant (Student Test, t(39)=6.98, p<0.001).

Conclusions

Deferasirox proves to be an effective iron chelator, the serum level of ferritine decreased for all the patients during the treatment and 22.5 % of the patients developed an erythroid improvement. Safety and compliance were good.

The iron chelator deferasirox synergises with chemotherapy to treat triple-negative breast cancers

To ensure their high proliferation rate, tumor cells have an iron metabolic disorder causing them to have increased iron needs, making them more susceptible to iron deprivation. This vulnerability could be a therapeutic target. In breast cancers, the development of new therapeutic approaches is urgently needed for patients with triple-negative tumors, which frequently relapse after chemotherapy and suffer from a lack of targeted therapies. In this study, we demonstrated that deferasirox (DFX) synergises with standard chemotherapeutic agents such as doxorubicin, cisplatin and carboplatin to inhibit cell proliferation and induce apoptosis and autophagy in triple-negative breast cancer (TNBC) cells. Moreover, the combination of DFX with doxorubicin and cyclophosphamide delayed recurrences in breast cancer patient-derived xenografts without increasing the side-effects of chemotherapies alone or altering the global iron storage of mice. Antitumor synergy of DFX and doxorubicin seems to involve downregulation of the phosphoinositide 3-kinase and nuclear factor-κB pathways. Iron deprivation in combination with chemotherapy could thus help to improve the effectiveness of chemotherapy in TNBC patients without increasing toxicity. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Prospective evaluation of the effect of deferasirox on hematologic response in transfusion-dependent patients with low-risk MDS and iron overload

OBJECTIVES

To assess the reduction of transfusions rate in transfusion-dependent patients with low-risk myelodysplastic syndrome (MDS) with iron overload treated with deferasirox.

METHODS

Prospective observational study. Primary endpoint was reduction in transfusion requirements (RTR) at 3 months, (assessed on 8-week period). Secondary endpoints were hematologic improvement according to International Working Group (IWG) 2006 criteria at 3, 6, and 12 months.

RESULTS

Fifty-seven patients were evaluable. After 3 months of chelation, no effect was seen on transfusion requirement (5.9 packed red blood cells (PRBC) vs 5.8 before chelation). According to the Kaplan-Meier analysis, the probability of RTR at 3, 6, and 12 months was assessed as 3.5%, 9.1%, and 18.7%, respectively. Median duration of RTR was 182 days. However, during the 12-month follow-up after deferasirox initiation, 17 patients (31.5%) achieved minor erythroid response [HI-E] according to IWG criteria, 10 of whom having achieved Hb improvement at month 12.

CONCLUSION

After 3 months of treatment, deferasirox had no impact on transfusion requirement in regularly transfused patients with low-risk MDS. However, deferasirox could induce 31% of erythroid response during the 12-month follow-up period thus suggesting that iron chelation therapy with deferasirox may induce an effect on hematopoiesis in a subset of patients with MDS and iron overload.

Hepcidin is an endogenous protective factor for osteoporosis by reducing iron levels

Postmenopausal osteoporosis is a global health issue. Although a lack of estrogen is considered the major reason for postmenopausal osteoporosis, other factors might also contribute the etiology of the disease. In previous reports, we and others proposed that iron accumulation after menopause accelerates osteoporosis, and here, we genetically modified the expression of an endogenous hormone, hepcidin, to modulate iron status in a mouse model. Our results show that hepcidin levels negatively correlate with bone loss in both knockout and overexpression (with ovariectomy) murine models. In addition, iron overload enhances reactive oxygen species (ROS) activity and attenuates the functions of primary osteoblasts, while iron depletion could reverse this phenomenon through inhibiting the functions of primary osteoclasts. Therefore, our results provide more evidence of the 'iron accumulation' hypothesis, which suggests that high iron levels are risk factors for osteoporosis, and the 'Huang's hypothesis' that hepcidin is a potential drug target for the prevention of postmenopausal osteoporosis.

Discovery of nicoyamycin A, an inhibitor of uropathogenic Escherichia coli growth in low iron environments

High-throughput screening and activity-guided purification identified nicoyamycin A, a natural product comprised of an uncommon 3-methyl-1,4-dioxane ring incorporated into a desferrioxamine-like backbone via a spiroaminal linkage. Nicoyamycin A potently inhibits uropathogenic Escherichia coli growth in low iron medium, a promising step toward developing novel antibiotics to treat recalcitrant bacterial infections.

Synergistic inhibitory effects of deferasirox in combination with decitabine on leukemia cell lines SKM-1, THP-1, and K-562

A multi-center study from the French Myelodysplastic Syndrome (MDS) Group confirmed that iron chelation therapy is an independent prognostic factor that can increase the survival rate of patients who are suffering from transfusion-dependent low-risk MDS. In this study, we aimed to explore this clinical phenomena in vitro, by exploring the synergistic effect of the iron chelator Deferasirox (DFX) and the DNA methyl transferase inhibitor Decitabine (DAC) in the leukemia cell lines SKM-1, THP-1, and K-562. Treatment with both DFX or DAC promoted apoptosis, induced cell cycle arrest, and inhibited proliferation in all three of these cell lines. The combination of DFX and DAC was much greater than the effect of using either drug alone. DFX showed a synergistic effect with DAC on cell apoptosis in all three cell lines and on cell cycle arrest at the G0/G1 phase in K-562 cells. DFX decreased the ROS levels to varying degrees. In contrast, DAC increased ROS levels and an increase in ROS was also noted when the two drugs were used in combination. Treatment of cells with DAC induced re-expression of ABAT, APAF-1, FADD, HJV, and SMPD3, presumably through demethylation. However the combination of DAC and DFX just had strong synergistic effect on the re-expression of HJV.

To chelate or not to chelate in MDS: That is the question!

Myelodysplastic syndromes (MDS) are a heterogeneous group of hemopathies that exhibit physical manifestations with clinical consequences of bone marrow failure and inherent risk of progression to acute myeloid leukemia. Iron overload (IO) is common in MDS due to chronic transfusion support and disease-related alterations in iron metabolism. IO has been conclusively associated with inferior outcomes among MDS patients. Despite lack of randomized trials showing a survival impact of iron chelation therapy (ICT), ICT is recommended by experts and guidelines for select MDS patients with IO and is often used. The availability of effective oral ICT agents has reignited the controversy regarding ICT use in patients with MDS and IO. Here we summarize the studies evaluating the value of ICT in MDS and suggest a practical approach for use of these therapies. We also highlight controversies regarding use of ICT in MDS and discuss some ongoing efforts to answer these questions.

The iron chelator deferasirox induces apoptosis by targeting oncogenic Pyk2/β-catenin signaling in human multiple myeloma

Deregulated iron metabolism underlies the pathogenesis of many human cancers. Recently, low expression of ferroportin, which is the only identified non-heme iron exporter, has been associated with significantly reduced overall survival in multiple myeloma (MM); however, the altered iron metabolism in MM biology remains unclear. In this study we demonstrated, by live cell imaging, that MM cells have increased intracellular iron levels as compared with normal cells. In experiments to test the effect of iron chelation on the growth of MM cells, we found that deferasirox (DFX), an oral iron chelator used to treat iron overload in clinical practice, inhibits MM cell growth both in vivo and in vitro. Mechanistically, DFX was found to induce apoptosis of MM cells via the inhibition of proline-rich tyrosine kinase 2 (Pyk2), which is known to promote tumor growth in MM. Inhibition of Pyk2 is caused by the suppression of reactive oxygen species, and leads to downregulation of the Wnt/β-catenin signaling pathway. Taken together, our findings indicate that high levels of intracellular iron, which might be due to low ferroportin expression, play a role in MM pathophysiology. Therefore, DFX may provide a therapeutic option for MM that is driven by deregulated iron homeostasis and/or Pyk2/Wnt signaling.

Reactive oxygen species levels control NF-κB activation by low dose deferasirox in erythroid progenitors of low risk myelodysplastic syndromes

Anemia is a frequent cytopenia in myelodysplastic syndromes (MDS) and most patients require red blood cell transfusion resulting in iron overload (IO). Deferasirox (DFX) has become the standard treatment of IO in MDS and it displays positive effects on erythropoiesis. In low risk MDS samples, mechanisms improving erythropoiesis after DFX treatment remain unclear. Herein, we addressed this question by using liquid cultures with iron overload of erythroid precursors treated with low dose of DFX (3μM), which corresponds to DFX 5 mg/kg/day, an unusual dose used for iron chelation. We highlight a decreased apoptosis rate and an increased proportion of cycling cells, both leading to higher proliferation rates. The iron chelation properties of low dose DFX failed to activate the Iron Regulatory Proteins and to support iron depletion, but low dose DFX dampers intracellular reactive oxygen species. Furthermore low concentrations of DFX activate the NF-κB pathway in erythroid precursors triggering anti-apoptotic and anti-inflammatory signals. Establishing stable gene silencing of the Thioredoxin (TRX) 1 genes, a NF-κB modulator, showed that fine-tuning of reactive oxygen species (ROS) levels regulates NF-κB. These results justify a clinical trial proposing low dose DFX in MDS patients refractory to erythropoiesis stimulating agents.