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Dysregulation of iron metabolism in cancer stem cells.
Recalcati, S, Gammella, E, Cairo, G
Free radical biology & medicine. 2019;:216-220
Abstract
Cancer stem cells (CSCs) are a distinct subpopulation of tumor cells endowed with stem-like properties. Importantly, CSCs can survive current standard therapies, resulting in metastatic disease and tumor recurrence. Here we describe the alterations of iron homeostasis occurring in CSCs, which in general are characterized by high intracellular iron content. Importantly, abnormalities of iron metabolism correlate with faster tumor growth and adverse prognosis in cancer patients. In line with the dependence of cancer on iron, we also discuss iron-dependent mechanisms as druggable pathways, as iron chelators have been considered for tumor therapy and new molecules currently proposed and studied as antineoplastic drugs may impinge on iron and its capacity to promote oxidative stress to have therapeutic value in cancer.
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2.
Strategies for managing transfusional iron overload: conventional treatments and novel strategies.
Sheth, S
Current opinion in hematology. 2019;(3):139-144
Abstract
PURPOSE OF REVIEW For individuals who have transfusion-dependent anemia, iron overload is the long-term complication, which results in significant morbidity. Ameliorating this is now the biggest unmet need. This review specifically addresses this issue. RECENT FINDINGS Over the last decade or so, major advances in the treatment of these individuals, has resulted from novel strategies aimed at reducing transfusion requirement as well as optimizing chelation therapy. This review will summarize these advances and provide insights into some of the therapies in the pipeline. Strategies aimed at reducing transfusion requirement include modulation of erythropoietic regulation by reducing ineffective red cell production through activin trapping, as well as stem cell gene modification approaches, which aim for a cure, and transfusion independence. Refined means of assessing tissue iron and the introduction of oral chelators have facilitated tailoring chelation regimens with closer monitoring and improved compliance. Newer approaches to ameliorate iron toxicity have focused on the hepcidin pathway, all of which would result in increased hepcidin levels and reduction of iron absorption from the intestine, sequestration of iron in normal storage sites and reduced exposure of more susceptible organs, such as the heart and endocrine organs, to the toxic effects of increased iron. SUMMARY These advances offer the promise of improved management of transfusion-dependent individuals.
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3.
Management of the aging beta-thalassemia transfusion-dependent population - The Italian experience.
Pinto, VM, Poggi, M, Russo, R, Giusti, A, Forni, GL
Blood reviews. 2019;:100594
Abstract
Thalassemia is among the most common monogenic diseases worldwide. Stem cell transplantation can be curative but is reserved for young patients, as probably gene therapy will be in the future. Adult thalassemia patients are treated with transfusion therapy and iron chelation, and improvements in the safety of transfusion protocols, use of iron chelation, monitoring of iron overload, and management of comorbidities have substantially prolonged survival, increasing the proportion of adult patients in the thalassemic population. However, older patients are more likely to develop multiple disease-related morbidities, including osteoporosis, endocrine disorders, liver disease, renal dysfunction, and cancer. Thus, the main objective of this article is to describe new challenges posed by the increasing life expectancy of patients with thalassemia, focusing on data from Italy where there is a well-documented history of thalassemia management. It is hoped that the mortality and morbidity benefits already seen in patients with thalassemia will continue to improve with ongoing advances in the quality of treatment.
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4.
Hematologic improvement with iron chelation therapy in myelodysplastic syndromes: Clinical data, potential mechanisms, and outstanding questions.
Leitch, HA, Gattermann, N
Critical reviews in oncology/hematology. 2019;:54-72
Abstract
Myelodysplastic syndromes (MDS) are clonal hematopoietic stem cell disorders characterized by cytopenias and progression to acute myeloid leukemia (AML). Although several treatments for MDS are available, the mainstay of therapy for most patients remains supportive care. This includes red blood cell (RBC) transfusion to correct anemia, which leads to iron overload. RBC transfusion dependence and iron overload portend inferior overall survival. Some studies indicate that iron chelation therapy (ICT) may have beneficial effects on clinical endpoints in MDS; however, these data are from non-randomized trials and the validity of the results is vigorously debated. A consistent observation in clinical studies of ICT in MDS has been hematologic improvement (HI) in some patients, including a reduction in RBC transfusion requirements and even transfusion independence. Here, we review data on HI with ICT in lower risk MDS, preclinical data examining mechanisms by which HI may occur, and identify areas for future investigation.
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5.
Effect of different iron chelation regimens on bone mass in transfusion-dependent thalassemia patients.
Bordbar, M, Haghpanah, S, Zekavat, OR, Saki, F, Bazrafshan, A, Bozorgi, H
Expert review of hematology. 2019;(11):997-1003
Abstract
Objectives: Iron overload might lead to bone loss in transfusion-dependent beta-thalassemia (TDT) patients. To investigate the role of iron chelation therapy (ICT) on bone mineral density (BMD) of TDT patients suffering from iron overload, the authors compared the efficacy of five different iron chelation regimens through assessing serum ferritin and BMD.Methods: In 256 consecutive TDT patients, BMD was measured by dual-energy X-ray absorptiometry in lumbar spine and femoral neck regions. Treatment outcome of five iron chelation regimens including Deferoxamine (DFO), Deferiprone (DFP), Deferasirox (DFX), and combination therapy was evaluated to compare the mean differences of serum ferritin and BMD indices pre- and post-treatment during 12-months follow-up period.Results: No significant difference was observed in DXA characteristics and serum ferritin level changes between ICT groups, but combination of DFO and DFX had the best outcome in improving bone mass through assessing each group individually.Conclusion: Combination therapy with DFX and DFO had the highest impact on reducing serum ferritin, however insignificant, and improving bone loss in both lumbar spine and femoral neck in comparison with other regimens. A randomized prospective clinical trial is advised to accurately assess the efficacy of iron chelation regimens on BMD measurements of TDT patients.
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6.
Iron and liver fibrosis: Mechanistic and clinical aspects.
Mehta, KJ, Farnaud, SJ, Sharp, PA
World journal of gastroenterology. 2019;(5):521-538
Abstract
Liver fibrosis is characterised by excessive deposition of extracellular matrix that interrupts normal liver functionality. It is a pathological stage in several untreated chronic liver diseases such as the iron overload syndrome hereditary haemochromatosis, viral hepatitis, alcoholic liver disease, non-alcoholic fatty liver disease, non-alcoholic steatohepatitis and diabetes. Interestingly, regardless of the aetiology, iron-loading is frequently observed in chronic liver diseases. Excess iron can feed the Fenton reaction to generate unquenchable amounts of free radicals that cause grave cellular and tissue damage and thereby contribute to fibrosis. Moreover, excess iron can induce fibrosis-promoting signals in the parenchymal and non-parenchymal cells, which accelerate disease progression and exacerbate liver pathology. Fibrosis regression is achievable following treatment, but if untreated or unsuccessful, it can progress to the irreversible cirrhotic stage leading to organ failure and hepatocellular carcinoma, where resection or transplantation remain the only curative options. Therefore, understanding the role of iron in liver fibrosis is extremely essential as it can help in formulating iron-related diagnostic, prognostic and treatment strategies. These can be implemented in isolation or in combination with the current approaches to prepone detection, and halt or decelerate fibrosis progression before it reaches the irreparable stage. Thus, this review narrates the role of iron in liver fibrosis. It examines the underlying mechanisms by which excess iron can facilitate fibrotic responses. It describes the role of iron in various clinical pathologies and lastly, highlights the significance and potential of iron-related proteins in the diagnosis and therapeutics of liver fibrosis.
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7.
Pantoprazole reduces serum ferritin in patients with thalassemia major and intermedia: A randomized, controlled study.
Eghbali, A, Khalilpour, A, Taherahmadi, H, Bagheri, B
Therapie. 2019;(5):507-512
Abstract
AIM: Complications due to iron overload exert a problematic situation in patients with thalassemia. Proton pump inhibitors (PPIs) like pantoprazole are effective agents to reduce acid gastric acid secretion and perhaps to interrupt iron absorption in conditions with increased iron absorption. Our purpose was to study effects of pantoprazole addition to chelators on iron levels in patients with thalassemia major and intermedia. METHODS This randomized, controlled, and single center trial was performed on 60 patients with thalassemia major and intermedia in Amir Kabir hospital, Iran. Patients were randomized 1:1 to pantoprazole group (iron chelator plus pantoprazole) or control group (iron chelator) for 6 months. Serum ferritin was measured by ELISA. Iron content was measured by magnetic resonance imaging; heart T2*, and liver T2*. RESULTS After 6 months of treatment, a significant reduction was seen in serum ferritin levels in the pantoprazole group (1444±613μg/mL to 1197±956μg/mL; P<0.001). A further reduction was seen in patients with thalassmeia intermedia. There were no significant changes in myocardial T2* values in pantoprazole group compared to control group (23.6±7.3ms to 24.1±6.4ms). Compared to the control group, pantoprazole therapy had no effect on hepatic T2* value (9.7±2.3ms to 9.8±2.6ms). However, between-group difference was significant (P<0.05). CONCLUSION Pantoprazole therapy for 6 months has benefits for reducing serum ferritin in patients with thalassemia major and intermedia. Pantoprazole addition to iron chelators seems safe.
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8.
New Insights into Oxidative Damage and Iron Associated Impairment in Traumatic Brain Injury.
Toro-Urrego, N, Turner, LF, Avila-Rodriguez, MF
Current pharmaceutical design. 2019;(45):4737-4746
Abstract
Traumatic Brain Injury is considered one of the most prevalent causes of death around the world; more than seventy millions of individuals sustain the condition per year. The consequences of traumatic brain injury on brain tissue are complex and multifactorial, hence, the current palliative treatments are limited to improve patients' quality of life. The subsequent hemorrhage caused by trauma and the ongoing oxidative process generated by biochemical disturbances in the in the brain tissue may increase iron levels and reactive oxygen species. The relationship between oxidative damage and the traumatic brain injury is well known, for that reason, diminishing factors that potentiate the production of reactive oxygen species have a promissory therapeutic use. Iron chelators are molecules capable of scavenging the oxidative damage from the brain tissue and are currently in use for ironoverload- derived diseases. Here, we show an updated overview of the underlying mechanisms of the oxidative damage after traumatic brain injury. Later, we introduced the potential use of iron chelators as neuroprotective compounds for traumatic brain injury, highlighting the action mechanisms of iron chelators and their current clinical applications.
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Ironing out the role of the cyclin-dependent kinase inhibitor, p21 in cancer: Novel iron chelating agents to target p21 expression and activity.
Moussa, RS, Park, KC, Kovacevic, Z, Richardson, DR
Free radical biology & medicine. 2019;:276-294
Abstract
Iron (Fe) has become an important target for the development of anti-cancer therapeutics with a number of Fe chelators entering human clinical trials for advanced and resistant cancer. An important aspect of the activity of these compounds is their multiple molecular targets, including those that play roles in arresting the cell cycle, such as the cyclin-dependent kinase inhibitor, p21. At present, the exact mechanism by which Fe chelators regulate p21 expression remains unclear. However, recent studies indicate the ability of chelators to up-regulate p21 at the mRNA level was dependent on the chelator and cell-type investigated. Analysis of the p21 promoter identified that the Sp1-3-binding site played a significant role in the activation of p21 transcription by Fe chelators. Furthermore, there was increased Sp1/ER-α and Sp1/c-Jun complex formation in melanoma cells, suggesting these complexes were involved in p21 promoter activation. Elucidating the mechanisms involved in the regulation of p21 expression in response to Fe chelator treatment in neoplastic cells will further clarify how these agents achieve their anti-tumor activity. It will also enhance our understanding of the complex roles p21 may play in neoplastic cells and lead to the development of more effective and specific anti-cancer therapies.
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An experimental investigation of a novel iron chelating protoporphyrin IX prodrug for the enhancement of photodynamic therapy.
Anayo, L, Magnussen, A, Perry, A, Wood, M, Curnow, A
Lasers in surgery and medicine. 2018;(5):552-565
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Abstract
OBJECTIVES Non-melanoma skin cancers are the most frequently occurring type of cancer worldwide. They can be effectively treated using topical dermatological photodynamic therapy (PDT) employing protoporphyrin IX (PpIX) as the active photosensitising agent as long as the disease remains superficial. Novel iron chelating agents are being investigated to enhance the effectiveness and extend the applications of this treatment modality, as limiting free iron increases the accumulation of PpIX available for light activation and thus cell kill. METHODS Human lung fibroblasts (MRC-5) and epithelial squamous carcinoma (A431) cells were treated with PpIX precursors (aminolaevulinic acid [ALA] or methyl-aminolevulinate [MAL]) with or without the separate hydroxypyridinone iron chelating agent (CP94) or alternatively, the new combined iron chelator and PpIX producing agent, AP2-18. PpIX fluorescence was monitored hourly for 6 hours prior to irradiation. PDT effectiveness was then assessed the following day using the lactate dehydrogenase and neutral red assays. RESULTS Generally, iron chelation achieved via CP94 or AP2-18 administration significantly increased PpIX fluorescence. ALA was more effective as a PpIX-prodrug than MAL in A431 cells, corresponding with the lower PpIX accumulation observed with the latter congener in this cell type. Addition of either iron chelating agent consistently increased PpIX accumulation but did not always convey an extra beneficial effect on PpIX-PDT cell kill when using the already highly effective higher dose of ALA. However, these adjuvants were highly beneficial in the skin cancer cells when compared with MAL administration alone. AP2-18 was also at least as effective as CP94 + ALA/MAL co-administration throughout and significantly better than CP94 supplementation at increasing PpIX fluorescence in MRC5 cells as well as at lower doses where PpIX accumulation was observed to be more limited. CONCLUSIONS PpIX fluorescence levels, as well as PDT cell kill effects on irradiation can be significantly increased by pyridinone iron chelation, either via the addition of CP94 to the administration of a PpIX precursor or alternatively via the newly synthesized combined PpIX prodrug and siderophore, AP2-18. The effect of the latter compound appears to be at least equivalent to, if not better than, the separate administration of its constituent parts, particularly when employing MAL to destroy skin cancer cells. AP2-18 therefore warrants further detailed analysis, as it may have the potential to improve dermatological PDT outcomes in applications currently requiring enhancement. Lasers Surg. Med. 50:552-565, 2018. © 2018 The Authors. Lasers in Surgery and Medicine Published by Wiley Periodicals, Inc.