Erythropoietin and cancer: the unintended consequences of anemia correction

Basic leucine zipper transcription activators - tools to improve production and quality of human erythropoietin in Nicotiana benthamiana

Human erythropoietin (hEPO) is one of the most in-demand biopharmaceuticals, however, its production is challenging. When produced in a plant expression system, hEPO results in extensive plant tissue damage and low expression. It is demonstrated that the modulation of the plant protein synthesis machinery enhances hEPO production. Co-expression of basic leucine zipper transcription factors with hEPO prevents plant tissue damage, boosts expression, and increases hEPO solubility. bZIP28 co-expression up-regulates genes associated with the unfolded protein response, indicating that the plant tissue damage caused by hEPO expression is due to the native protein folding machinery being overwhelmed and that this can be overcome by co-expressing bZIP28.

Erythropoietin: A Personal Alice in Wonderland Trip in the Shadow of the Giants

The identification of the hormone erythropoietin (EPO), which regulates red blood cell production, and its development into a pharmaceutical-grade product to treat anemia has been not only a herculean task but it has also been the first of its kind. As with all the successes, it had "winners" and "losers", but its history is mostly told by the winners who, over the years, have published excellent scientific and divulgate summaries on the subject, some of which are cited in this review. In addition, "success" is also due to the superb and dedicated work of numerous "crew" members, who often are under-represented and under-recognized when the story is told and often have several "dark sides" that are not told in the polished context of most reviews, but which raised the need for the development of the current legislation on biotherapeutics. Although I was marginally involved in the clinical development of erythropoietin, I have known on a personal basis most, if not all, the protagonists of the saga and had multiple opportunities to talk with them on the drive that supported their activities. Here, I will summarize the major steps in the development of erythropoietin as the first bioproduct to enter the clinic. Some of the "dark sides" will also be mentioned to emphasize what a beautiful achievement of humankind this process has been and how the various unforeseen challenges that emerged were progressively addressed in the interest of science and of the patient's wellbeing.

A Rationally Designed Complex Replenishes the Transferrin Iron Pool Directly and with High Specificity

Many forms of anemia are caused or complicated by pathologic restriction of iron (Fe). Chronic inflammation and certain genetic mutations decrease the activity of ferroportin, the only Fe-exporter protein, so that endogenously recycled or nutritionally absorbed Fe cannot be exported to the extracellular Fe carrier protein transferrin for delivery to the bone marrow. Diminished ferroportin activity renders anemia correction challenging as Fe administered intravenously or through nutritional supplementation is trafficked through the ferroportin-transferrin axis. Utilizing judicious application of coordination chemistry principles, we designed an Fe complex (Fe-BBG) with solution thermodynamics and Fe dissociation kinetics optimized to replenish the transferrin-Fe pool rapidly, directly, and with precision. Fe-BBG is unreactive under conditions designed to force redox cycling and production of reactive oxygen species. The BBG ligand has a low affinity for divalent metal ions and does not compete for binding of other endogenously present ions including Cu and Zn. Treatment with Fe-BBG confers anemia correction in a mouse model of iron-refractory iron-deficiency anemia. Repeated exposure to Fe-BBG did not cause adverse clinical chemistry changes or trigger the expression of genes related to oxidative stress or inflammation. Fe-BBG represents the first entry in a promising new class of transferrin-targeted Fe replacement drugs.

Diagnostic Imaging Studies on Local and Systemic Erythropoietin Application for Promoting Bone Regeneration in Rat Calvarial Defects

The purpose of this study was to compare the effects of local and systemic application of recombinant human erythropoietin (rhEPO) on the healing of rat calvarial defects. Twenty-four male skeletally-mature Wistar rats were used. Two bone 5 mm critical size defects were created in calvarial bones of each rat. In rats from experimental group I (n = 12), EPO was applied locally on a collagen cone in left defects, whereas a collagen cone soaked with physiological saline was placed in right defects. The rats from experimental group II were injected once intraperitoneally with 4900 IU/kg EPO; a collagen cone was only placed in left defects, whereas the right defects were left empty. The systemic effect of EPO treatment was monitored by haematological analyses on days 0, 30 and 90. Bone healing was monitored via radiography and computed tomography on the same time intervals. The results demonstrated that local EPO application had no significant effect on haemopoiesis, unlike the systemic application. At the same time, it resulted in new bone formation and therefore, could be successfully used as a means of promoting bone regeneration.

Predicting survival and immune microenvironment in colorectal cancer: a STAT signaling-related signature

BACKGROUND

Despite research advances, studies on predictive models of colorectal cancer (CRC) remain scarce and none have evaluated signal transducer and activator of transcription (STAT) signaling.

AIM

To develop an effective prognostic signature for and evaluate its association with immune microenvironment.

DESIGN

Comprehensive analysis based on The Cancer Genome Atlas and Gene Expression Omnibus databases with experimental validation.

METHODS

Gene expression and clinical profiles of CRC patients were extracted from the databases. Differentially expressed genes with prognostic values were used to construct a signature. Immune cell infiltration and composition were further evaluated by TIMER, single-sample gene set enrichment and CIBERSORT analyses. The impact of the hub gene Caveolin-1 (CAV1) on cell proliferation, apoptosis, senescence and tumor angiogenesis was experimentally validated.

RESULTS

The five-gene-based STAT signaling-related prognostic signature was significantly associated with CRC survival, and the nomogram was with improved prognostic efficacy than the conventional TNM stage. The STAT signaling-related signature was correlated with tumor immune microenvironment. CAV1 was further identified as the hub gene within the signature. CAV1 inhibits the proliferation and induces the apoptosis as well as senescence of CRC cells. In addition, the tumor angiogenesis of CRC can be suppressed by CAV1 overexpression.

CONCLUSIONS

The STAT signaling-related signature effectively predicts the prognosis and regulates tumor immune microenvironment in CRC. Our study underscores the role of STAT regulator, CAV1, as an important tumor suppressor in CRC carcinogenesis. Modulating STAT and its regulators could be a promising strategy for CRC in clinical practice.

Rational Approach to Finding Genes Encoding Molecular Biomarkers: Focus on Breast Cancer

Early detection of cancer facilitates treatment and improves patient survival. We hypothesized that molecular biomarkers of cancer could be rationally predicted based on even partial knowledge of transcriptional regulation, functional pathways and gene co-expression networks. To test our data mining approach, we focused on breast cancer, as one of the best-studied models of this disease. We were particularly interested to check whether such a ‘guilt by association’ approach would lead to pan-cancer markers generally known in the field or whether molecular subtype-specific ‘seed’ markers will yield subtype-specific extended sets of breast cancer markers. The key challenge of this investigation was to utilize a small number of well-characterized, largely intracellular, breast cancer-related proteins to uncover similarly regulated and functionally related genes and proteins with the view to predicting a much-expanded range of disease markers, especially that of extracellular molecular markers, potentially suitable for the early non-invasive detection of the disease. We selected 23 previously characterized proteins specific to three major molecular subtypes of breast cancer and analyzed their established transcription factor networks, their known metabolic and functional pathways and the existing experimentally derived protein co-expression data. Having started with largely intracellular and transmembrane marker ‘seeds’ we predicted the existence of as many as 150 novel biomarker genes to be associated with the selected three major molecular sub-types of breast cancer all coding for extracellularly targeted or secreted proteins and therefore being potentially most suitable for molecular diagnosis of the disease. Of the 150 such predicted protein markers, 114 were predicted to be linked through the combination of regulatory networks to basal breast cancer, 48 to luminal and 7 to Her2-positive breast cancer. The reported approach to mining molecular markers is not limited to breast cancer and therefore offers a widely applicable strategy of biomarker mining.

Erythropoietin receptor regulates tumor mitochondrial biogenesis through iNOS and pAKT

Erythropoietin receptor (EPOR) is widely expressed in healthy and malignant tissues. In certain malignancies, EPOR stimulates tumor growth. In healthy tissues, EPOR controls processes other than erythropoiesis, including mitochondrial metabolism. We hypothesized that EPOR also controls the mitochondrial metabolism in cancer cells. To test this hypothesis, we generated EPOR-knockdown cancer cells to grow tumor xenografts in mice and analyzed tumor cellular respiration via high-resolution respirometry. Furthermore, we analyzed cellular respiratory control, mitochondrial content, and regulators of mitochondrial biogenesis in vivo and in vitro in different cancer cell lines. Our results show that EPOR controls tumor growth and mitochondrial biogenesis in tumors by controlling the levels of both, pAKT and inducible NO synthase (iNOS). Furthermore, we observed that the expression of EPOR is associated with the expression of the mitochondrial marker VDAC1 in tissue arrays of lung cancer patients, suggesting that EPOR indeed helps to regulate mitochondrial biogenesis in tumors of cancer patients. Thus, our data imply that EPOR not only stimulates tumor growth but also regulates tumor metabolism and is a target for direct intervention against progression.

Enhancing Erythropoiesis by a Phytoestrogen Diarylheptanoid from Curcuma comosa

Erythropoietin (Epo) is widely used for the treatment of anemia; however, non-hematopoietic effects and cancer risk limit its clinical applications. Therefore, alternative molecules to improve erythropoiesis in anemia patients are urgently needed. Here, we investigated the potential effects of a phytoestrogen diarylheptanoid (3R)-1,7-diphenyl-(4E,6E)-4,6-heptadien-3-ol, (ASPP 049) isolated from Curcuma comosa on promoting erythropoiesis. Treatment with C. comosa extract improved anemia symptoms demonstrated by increasing red blood cell numbers, hematocrit, and hemoglobin content in anemic mice. In addition, ASPP 049, the major compound isolated from C. comosa, enhanced the suboptimal Epo dosages to improve erythroid cell differentiation from hematopoietic stem cells, which was inhibited by the estrogen receptor (ER) antagonist, ICI 182,780. Moreover, the ASPP 049-activated Epo-Epo receptor (EpoR) complex subsequently induced phosphorylation of EpoR-mediated erythropoiesis pathways: STAT5, MAPK/ERK, and PI3K/AKT in Epo-sensitive UT-7 cells. Taken together, these results suggest that C. comosa extract and ASPP 049 increased erythropoiesis through ER- and EpoR-mediated signaling cascades. Our findings provide insight into the specific interaction between a phytoestrogen diarylheptanoid and Epo-EpoR in a hematopoietic system for the potential treatment of anemia.

Human constitutive androstane receptor represses liver cancer development and hepatoma cell proliferation by inhibiting erythropoietin signaling

The constitutive androstane receptor (CAR) is a nuclear receptor that plays a crucial role in regulating xenobiotic metabolism and detoxification, energy homeostasis, and cell proliferation by modulating the transcription of numerous target genes. CAR activation has been established as the mode of action by which phenobarbital-like nongenotoxic carcinogens promote liver tumor formation in rodents. This paradigm, however, appears to be unrelated to the function of human CAR (hCAR) in hepatocellular carcinoma (HCC), which remains poorly understood. Here, we show that hCAR expression is significantly lower in HCC than that in adjacent nontumor tissues and, importantly, reduced hCAR expression is associated with a worse HCC prognosis. We also show overexpression of hCAR in human hepatoma cells (HepG2 and Hep3B) profoundly suppressed cell proliferation, cell cycle progression, soft-agar colony formation, and the growth of xenografts in nude mice. RNA-Seq analysis revealed that the expression of erythropoietin (EPO), a pleiotropic growth factor, was markedly repressed by hCAR in hepatoma cells. Addition of recombinant EPO in HepG2 cells partially rescued hCAR-suppressed cell viability. Mechanistically, we showed that overexpressing hCAR repressed mitogenic EPO-EPO receptor signaling through dephosphorylation of signal transducer and activator of transcription 3, AKT, and extracellular signal-regulated kinase 1/2. Furthermore, we found that hCAR downregulates EPO expression by repressing the expression and activity of hepatocyte nuclear factor 4 alpha, a key transcription factor regulating EPO expression. Collectively, our results suggest that hCAR plays a tumor suppressive role in HCC development, which differs from that of rodent CAR and offers insight into the hCAR-hepatocyte nuclear factor 4 alpha-EPO axis in human liver tumorigenesis.

Erythropoietin alleviates acute lung injury induced by ischemia-reperfusion through blocking p38 MAPK signaling

Erythropoietin (EPO) has antiapoptotic, antioxidative, and anti-inflammatory effects on ischemia tissues and protects against acute lung injury (ALI) induced by ischemia-reperfusion (I/R). p38 mitogen-activated protein kinases (p38 MAPK) signaling is involved in the processes of I/R-induced ALI. However, the interaction of EPO with p38 MAPK signaling in I/R-induced ALI has not been reported. To explore this issue, we constructed an I/R-induced ALI model in vivo and in vitro using Sprague Dawley rats and BEAS-2B cells. Some I/R rats and hypoxia-reoxygenation (H/R)-induced cells were treated with EPO, and the others were used as control groups. The injuries of lung tissues and cells were respectively assessed by inflammatory cytokine, morphologic changes, cell viability, apoptosis, and oxidative damage-related factors. Western blot determined key proteins in the p38 MAPK signaling. Results indicated that I/R induced the increase of inflammatory factors, lung weight, filtration coefficient, bronchoalveolar lavage fluid protein content, apoptosis, neutrophil, and lung peroxidation, and H/R caused cell growth inhibition, apoptosis, and oxidative damage-related factors' release. EPO attenuated I/R-induced injury in vivo and in vitro. Furthermore, the increase of p-p38, p-JNK, and p-ERK1/2 in lung tissues and cells induced by I/R was downregulated by EPO. Moreover, both EPO and an inhibitor of p38 MAPK (SB203580) alleviated H/R-induced cell injury. Erythropoietin along with SB203580 had more obvious protection effects than EPO alone. Collectively, EPO alleviated I/R-induced ALI by blocking p38 MAPK signaling. The interaction mechanism of EPO with p38 MAPK signaling contributes to understanding the processes of I/R-induced ALI and provides new insights for the disease treatment.

Immunoaffinity Capillary Electrophoresis in the Era of Proteoforms, Liquid Biopsy and Preventive Medicine: A Potential Impact in the Diagnosis and Monitoring of Disease Progression

Over the years, multiple biomarkers have been used to aid in disease screening, diagnosis, prognosis, and response to therapy. As of late, protein biomarkers are gaining strength in their role for early disease diagnosis and prognosis in part due to the advancements in identification and characterization of a distinct functional pool of proteins known as proteoforms. Proteoforms are defined as all of the different molecular forms of a protein derived from a single gene caused by genetic variations, alternative spliced RNA transcripts and post-translational modifications. Monitoring the structural changes of each proteoform of a particular protein is essential to elucidate the complex molecular mechanisms that guide the course of disease. Clinical proteomics therefore holds the potential to offer further insight into disease pathology, progression, and prevention. Nevertheless, more technologically advanced diagnostic methods are needed to improve the reliability and clinical applicability of proteomics in preventive medicine. In this manuscript, we review the use of immunoaffinity capillary electrophoresis (IACE) as an emerging powerful diagnostic tool to isolate, separate, detect and characterize proteoform biomarkers obtained from liquid biopsy. IACE is an affinity capture-separation technology capable of isolating, concentrating and analyzing a wide range of biomarkers present in biological fluids. Isolation and concentration of target analytes is accomplished through binding to one or more biorecognition affinity ligands immobilized to a solid support, while separation and analysis are achieved by high-resolution capillary electrophoresis (CE) coupled to one or more detectors. IACE has the potential to generate rapid results with significant accuracy, leading to reliability and reproducibility in diagnosing and monitoring disease. Additionally, IACE has the capability of monitoring the efficacy of therapeutic agents by quantifying companion and complementary protein biomarkers. With advancements in telemedicine and artificial intelligence, the implementation of proteoform biomarker detection and analysis may significantly improve our capacity to identify medical conditions early and intervene in ways that improve health outcomes for individuals and populations.

Molecular Pathways Involved in the Development of Congenital Erythrocytosis

Patients with idiopathic erythrocytosis are directed to targeted genetic testing including nine genes involved in oxygen sensing pathway in kidneys, erythropoietin signal transduction in pre-erythrocytes and hemoglobin-oxygen affinity regulation in mature erythrocytes. However, in more than 60% of cases the genetic cause remains undiagnosed, suggesting that other genes and mechanisms must be involved in the disease development. This review aims to explore additional molecular mechanisms in recognized erythrocytosis pathways and propose new pathways associated with this rare hematological disorder. For this purpose, a comprehensive review of the literature was performed and different in silico tools were used. We identified genes involved in several mechanisms and molecular pathways, including mRNA transcriptional regulation, post-translational modifications, membrane transport, regulation of signal transduction, glucose metabolism and iron homeostasis, which have the potential to influence the main erythrocytosis-associated pathways. We provide valuable theoretical information for deeper insight into possible mechanisms of disease development. This information can be also helpful to improve the current diagnostic solutions for patients with idiopathic erythrocytosis.

Upregulation of erythropoietin and erythropoietin receptor in castration-resistant progression of prostate cancer

Hypoxia-induced erythropoietin signaling plays an important role in tumor growth and invasion. In the present study, we investigated the contribution of erythropoietin signaling pathway to castration-resistant prostate cancer and the development of a neuroendocrine phenotype. Immunohistochemical staining showed that the erythropoietin and erythropoietin receptor scores in castration-resistant prostate cancer and androgen-dependent prostate cancer were 7.55 versus 4.5 and 7.45 versus 5.9,respectively (P < 0.001). Furthermore, a cell proliferation assay was conducted, and the differential expression of erythropoietin and erythropoietin receptor in LNCaP cells and hypoxia-induced LNCaP cells was evaluated using western blot and quantitative real-time PCR. The proliferation capacity of hypoxia-induced LNCaP cells was similar in cultures of both fetal bovine serum and charcoal-stripped fetal bovine serum, suggesting that LNCaP cells acquired hypoxia-induced androgen-independent growth. After 2 weeks of hypoxic culture, LNCaP cells showed a neuroendocrine cell change and increased expression of neuron-specific enolase, erythropoietin, and erythropoietin receptor; knockdown of erythropoietin receptor reversed the hypoxia-induced upregulation of neuron-specific enolase in the LNCaP cells. In conclusion, the concurrent upregulation of erythropoietin and erythropoietin receptor in castration-resistant prostate cancer suggests that the erythropoietin/erythropoietin receptor autocrine loop plays an important role in the progression of castration resistance and is responsible for the development of a neuroendocrine phenotype.

Rapid and selective detection of recombinant human erythropoietin in human blood plasma by a sensitive optical sensor

Recombinant human erythropoietin (rHuEPO) is an important hormone drug that is used to treat several medical conditions. It is also frequently abused by athletes as a performance enhancing agent at sporting events. The time window of the rHuEPO in blood is short. Therefore, the rapid detection of rHuEPO use/abuse at points of care and in sports requires a selective analytical method and a sensitive sensor. Herein, we present a highly selective method for the rapid detection of rHuEPO in human blood plasma by a sensitive optical sensor. rHuEPO is selectively extracted from human blood plasma by a target-specific extractor chip and converted into a biothiol by reducing its disulfide bond structure. The formed biothiol reacts with a water soluble (E)-1-((6-methoxybenzo[d]thiazole-2-yl)diazenyl)naphthalene-2,6-diolHg(ii) (BAN-Hg) optical sensor and causes its rapid decomposition. This leads to a rapid change in the sensor color from blue to pink that can be observed by the naked eye. The optical sensor was used to quantify rHuEPO in the concentration range 1 × 10-8 M to 1 × 10-12 M by UV-Vis spectroscopy. For the screening of blood plasma, an EPO-specific extractor chip was synthesized and used to selectively extract the protein from the biological matrix prior to its conversion into biothiol and quantification by the optical sensor. Since many proteins have a disulfide bond structure, the new method has strong potential for their rapid sensitive and selective detection by the BAN-Hg sensor and UV-Vis spectroscopy.

The Role of Tubule-Interstitial Crosstalk in Renal Injury and Recovery

Renal epithelial cells show remarkable regenerative capacity to recover from acute injury, which involves specific phenotypic changes, but also significant profibrotic tubule-interstitial crosstalk. Tubule-derived profibrotic stimuli and subsequent myofibroblast activation and extracellular matrix deposition have been linked closely with decline of renal function and nephron loss. However, recent data have questioned the view of purely detrimental effects of myofibroblast activation in the injured kidney and even suggested its beneficial role for epithelial regeneration. This article reviews the current understanding of the underlying mechanisms of tubular cell turnover, new suggested pathways of proregenerative tubular-interstitial crosstalk, and relevant insights of proliferation-enhancing effects of myofibroblasts on epithelial cells in nonrenal tissues.

Recombinant Human erythropoietin reduces viability of MCF-7 breast cancer cells from 3D culture without caspase activation

Recombinant human erythropoietin (rHuEPO) is the erythropoiesis-stimulating hormone that is being used concurrently with chemotherapeutic drugs in the treatment of anemia of cancer. The effect of rHuEPO on cancer cells in 3-dimensional (3D) cultures is not known. The objective of the study was to determine the effect of rHuEPO on the viability of MCF-7 breast cancer cells from 2-dimensional (2D) and 3D cell cultures. The monolayer MCF-7 cells from 2D culture and MCF-7 cell from 3D culture generated by ultra-low adhesive microplate technique, were treated with 0, 0.1, 10, 100 or 200 IU/mL rHuEPO for 24, 48 or 72 h. The effects of rHuEPO on MCF-7 cell viability and proliferation were determined using the (4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay (MTT), neutral red retention time (NRRT), trypan blue exclusion assay (TBE), DNA fragmentation, acridine orange/propidium iodide staining (AO/PI) assays. The MCF-7 cells for 3D culture were also subjected to caspase assays and cell cycle analysis using flow cytometry. rHuEPO appeared to have greater effect at lowering the viability of MCF-7 cells from 3D than 2D cultures. rHuEPO significantly (p < 0.05) decreased viability and down-regulated the caspase activities of 3D MCF-7 cells in dose- and time-dependent manner. The cell cycle analysis showed that rHuEPO caused MCF-7 cells to enter the subG0/G1 phase. Thus, the study suggests that rHuEPO has a cytostatic effect on the MCF-7 breast cancer cells from 3D culture.

SOCS, SPRED, and NR4a: Negative regulators of cytokine signaling and transcription in immune tolerance

Cytokines are important intercellular communication tools for immunity. Most cytokines utilize the JAK-STAT and Ras-ERK pathways to promote gene transcription and proliferation; however, this signaling is tightly regulated. The suppressor of cytokine signaling (SOCS) family and SPRED family are a representative negative regulators of the JAK-STAT pathway and the Ras-ERK pathway, respectively. The SOCS family regulates the differentiation and function of CD4⁺ T cells, CD8⁺ T cells, and regulatory T cells, and is involved in immune tolerance, anergy, and exhaustion. SPRED family proteins have been shown to inactivate Ras by recruiting the Ras-GTPase neurofibromatosis type 1 (NF1) protein. Human genetic analysis has shown that SOCS family members are strongly associated with autoimmune diseases, allergies, and tumorigenesis, and SPRED1 is involved in NF1-like syndromes and tumors. We also identified the NR4a family of nuclear receptors as a key transcription factor for immune tolerance that suppresses cytokine expression and induces various immuno-regulatory molecules including SOCS1.

Preclinical studies on pleiotropic functions of erythropoietin on bone healing

Erythropoietin (ЕPО) is a glycoprotein hormone, mainly known for its haemopoietic function. For orthopaedics, its pleiotropic effects – osteogenic and angiogenic potential, are of primary interest. The exact mechanism of EPO action is still unclear. The effects of EPO on bone healing were investigated through experiments with rats, mice, rabbits and pigs. Each of used models for experimental bone defects (calvarial models, long bone segmental defects, posterolateral spinal fusion and corticosteroid-induced femoral head osteonecrosis) has specific advantages and flaws. Obtaining specific and correct results is largely dependent on the used model. The brief evaluation of models could serve for standardisation of preclinical studies on bone regeneration.

Revisiting the treatment of anemia in the setting of chronic kidney disease, hematologic malignancies, and cancer: perspectives with opinion and commentary

INTRODUCTION

Anemia has and will continue to be a central theme in medicine particularly as clinicians are treating a burgeoning population of complex multi-organ system processes. As a result of multiple randomized controlled trials (RCTs), meta-analyses, and societal recommendations overly restrictive paradigms and under-administration of erythropoiesis stimulating agents (ESAs) have likely been followed by clinicians among all specialties.

AREAS COVERED

A review of anemia in the context of chronic kidney disease, hematologic malignancies, and cancer is presented with focus on the establishment of ESAs as integral in the treatment of anemia. Multiple RCTs and meta-analyses studying the use of ESAs are presented with focus upon their application to clinical practice. A 'compendium' is proffered describing the evolution, establishment, and implications of ESA administration initially among those with CKD with rapid subsequent application to the Hematology-Oncology population of patients. Literature search methodologies have included MEDLINE (1985-2020), PubMed (1996-2020), Cochrane Central Trials (1985-2020), EMBASE (2000-2020), and ClinicalTrials.gov (2000-2020).

EXPERT OPINION

Upon evaluation of risks and benefits of ESAs focused opinion and commentary is made supporting more liberal use of these agents and strongly suggesting that the current underlying treatment 'pendulum' has perhaps shifted too far to the 'under-treatment' side in many cases.

Lysophosphatidic acid receptors 2 and 3 regulate erythropoiesis at different hematopoietic stages

Hematopoiesis, the complex developmental process that forms blood components and replenishes the blood system, involves multiple intracellular and extracellular mechanisms. We previously demonstrated that lysophosphatidic acid (LPA), a lipid growth factor, has opposing regulatory effects on erythrocyte differentiation through activation of LPA receptors 2 and 3; yet the mechanisms underlying this process remain unclear. In this study, LPA₂ is observed that highly expressed in common myeloid progenitors (CMP) in murine myeloid cells, whereas the expression of LPA₃ displaces in megakaryocyte-erythroid progenitors (MEP) of later stage of myeloid differentiation. Therefore, we hypothesized that the switching expression of LPA₂ and LPA₃ determine the hematic homeostasis of mammalian megakaryocytic-erythroid lineage. In vitro colony-forming unit assays of murine progenitors reveal that LPA₂ agonist GRI reduces the erythroblast differentiation potential of CMP. In contrast, LPA₃ agonist OMPT increases the production of erythrocytes from megakaryocyte-erythrocyte progenitor cells (MEP). In addition, treatment with GRI reduces the erythroid, CMP, and MEP populations in mice, indicating that LPA₂ predominantly inhibits myeloid differentiation at an early stage. In contrast, activation of LPA₃ increases the production of terminally differentiated erythroid cells through activation of erythropoietic transcriptional factor. We also demonstrate that the LPA₃ signaling is essential for restoration of phenylhydrazine (PHZ)-induced acute hemolytic anemia in mice and correlates to erythropoiesis impairment of Hutchinson-Gilford progeria Symptom (HGPS) premature aging expressed K562 model. Our results reveal the distinct roles of LPA₂ and LPA₃ at different stages of hematopoiesis in vivo, providing potentiated therapeutic strategies of anemia treatment.

Erythropoietin regulation of red blood cell production: from bench to bedside and back

More than 50 years of efforts to identify the major cytokine responsible for red blood cell (RBC) production (erythropoiesis) led to the identification of erythropoietin (EPO) in 1977 and its receptor (EPOR) in 1989, followed by three decades of rich scientific discovery. We now know that an elaborate oxygen-sensing mechanism regulates the production of EPO, which in turn promotes the maturation and survival of erythroid progenitors. Engagement of the EPOR by EPO activates three interconnected signaling pathways that drive RBC production via diverse downstream effectors and simultaneously trigger negative feedback loops to suppress signaling activity. Together, the finely tuned mechanisms that drive endogenous EPO production and facilitate its downstream activities have evolved to maintain RBC levels in a narrow physiological range and to respond rapidly to erythropoietic stresses such as hypoxia or blood loss. Examination of these pathways has elucidated the genetics of numerous inherited and acquired disorders associated with deficient or excessive RBC production and generated valuable drugs to treat anemia, including recombinant human EPO and more recently the prolyl hydroxylase inhibitors, which act partly by stimulating endogenous EPO synthesis. Ongoing structure-function studies of the EPOR and its essential partner, tyrosine kinase JAK2, suggest that it may be possible to generate new "designer" drugs that control selected subsets of cytokine receptor activities for therapeutic manipulation of hematopoiesis and treatment of blood cancers.

Arterial hypertension in patients under antineoplastic therapy: a systematic review

BACKGROUND

Cardio-oncology aims to mitigate adverse cardiovascular manifestations in cancer survivors, but treatment-induced hypertension or aggravated hypertension has received less attention in these high cardiovascular risk patients.

METHODS

In this systematic review, we searched literature for contemporary data on the prevalence, pathophysiologic mechanisms, treatment implications and preventive strategies of hypertension in patients under antineoplastic therapy.

RESULTS

Several classes of antineoplastic drugs, including mainly vascular endothelial growth factor inhibitors, proteasome inhibitors, cisplatin derivatives, corticosteroids or radiation therapy were consistently associated with increased odds for new-onset hypertension or labile hypertensive status in previous controlled patients. Moreover, hypertension constitutes a major risk factor for chemotherapy-induced cardiotoxicity, which is the most serious cardiovascular adverse effect of antineoplastic therapy. Despite the heterogeneity of pooled studies, the pro-hypertensive profile of examined drug classes could be attributed to common structural and functional disorders. Importantly, certain antihypertensive drugs are considered to be more effective in the management of hypertension in this population and may partially attenuate indirect complications of cancer treatment, such as progressive development of cardiomyopathy and/or cardiovascular death. Nonpharmacological approaches to alleviate hypertension in cancer patients are also described, albeit adjudicated as less effective in general.

CONCLUSION

A growing body of evidence suggests that multiple antineoplastic agents increase the rate of progression of hypertension. Physicians need to balance the life-saving cancer treatment and the inflated risk of adverse cardiovascular events due to suboptimal management of hypertension in order to achieve improved clinical outcomes and sustained survival for their patients.

Erythropoietin Signaling in the Microenvironment of Tumors and Healthy Tissues

Erythropoietin (EPO), the primary cytokine of erythropoiesis, stimulates both proliferation and differentiation of erythroid progenitors and their maturation to red blood cells. Basal EPO levels maintain the optimum levels of circulating red blood cells. However, during hypoxia, EPO secretion and its expression is elevated drastically in renal interstitial fibroblasts, thereby increasing the number of erythroid progenitors and accelerating their differentiation to mature erythrocytes. A tight regulation of this pathway is therefore of paramount importance. The biological response to EPO is commenced through the involvement of its cognate receptor, EPOR. The receptor-ligand complex results in homodimerization and conformational changes, which trigger downstream signaling events and cause activation or inactivation of critical transcription factors that promote erythroid expansion. In recent years, recombinant human EPO (rEPO) has been widely used as a therapeutic tool to treat a number of anemias induced by infection, and chemotherapy for various cancers. However, several studies have uncovered a tumor promoting ability of EPO in man, which likely occurs through EPOR or alternative receptor(s). On the other hand, some studies have demonstrated a strong anticancer activity of EPO, although the mechanism still remains unclear. A thorough investigation of EPOR signaling could yield enhanced understanding of the pathobiology for a variety of disorders, as well as the potential novel therapeutic strategies. In this chapter, in addition to the clinical relevance of EPO/EPOR signaling, we review its anticancer efficacy within various tumor microenvironments.

Real-World Data on Cabozantinib in Previously Treated Patients with Metastatic Renal Cell Carcinoma: Focus on Sequences and Prognostic Factors

Cabozantinib is approved for the treatment of renal cell carcinoma (RCC). However, prognostic factors are still lacking in this context. The aim of this study was to evaluate prognostic factors in RCC patients treated with second- or third-line cabozantinib. A multicenter retrospective real-world study was conducted, involving 32 worldwide centers. A total of 237 patients with histologically confirmed clear-cell and non-clear-cell RCC who received cabozantinib as second- or third-line therapy for metastatic disease were included. We analyzed overall survival (OS), progression-free survival (PFS) and time-to-strategy failure (TTSF) using Kaplan–Meier curves. Cox proportional models were used at univariate and multivariate analyses.The median PFS and OS of cabozantinib were 7.76 months (95% CI 6.51–10.88) and 11.57 months (95% CI 10.90–not reached (NR)) as second-line and 11.38 months (95% CI 5.79–NR) and NR (95% CI 11.51–NR) as third-line therapy. The median TTSF and OS were 11.57 and 15.52 months with the sequence of cabozantinib–nivolumab and 25.64 months and NR with nivolumab–cabozantinib, respectively. The difference between these two sequences was statistically significant only in good-risk patients. In the second-line setting, hemoglobin (Hb) levels (HR= 2.39; 95% CI 1.24–4.60, p = 0.009) and IMDC (International Metastatic Renal Cell Carcinoma Database Consortium) group (HR = 1.72, 95% CI 1.04–2.87, p = 0.037) were associated with PFS while ECOG-PS (HR = 2.33; 95%CI, 1.16–4.69, p = 0.018) and Hb levels (HR = 3.12; 95%CI 1.18–8.26, p = 0.023) correlated with OS at multivariate analysis, while in the third-line setting, only Hb levels (HR = 2.72; 95%CI 1.04–7.09, p = 0.042) were associated with OS. Results are limited by the retrospective nature of the study.This real-world study provides evidence on the presence of prognostic factors in RCC patients receiving cabozantinib.

Effect of fetal bovine serum on erythropoietin receptor expression and viability of breast cancer cells

Erythropoietin receptors (EPORs) are present not only in erythrocyte precursors but also in non-hematopoietic cells including cancer cells. In this study, we determined the effect of fetal bovine serum (FBS) in culture medium on the EPOR expression and viability of the estrogen receptor (ER)-positive MCF-7 and ER-negative MDA-MB-231 breast cancer cells. Using flow cytometry, we showed that the inclusion of 10% FBS in the medium increased the EPOR expressions and viabilities of MDA-MB-231 and MCF-7 cells. The MDA-MB-231 showed greater EPOR expression than MCF-7 cells, suggesting that the presence of ERs on cells is associated with poor expression of EPOR. Culture medium containing 10% FBS also caused increased number of breast cancer cells entering the synthesis phase of the cell cycle. The study also showed that rHuEPO treatment did not affect viability of breast cancer cells. In conclusion, it was shown that the inclusion of FBS in culture medium increased expression of EPOR in breast cancer cells and rHuEPO treatment had no effect on the proliferation of these cancer cells.

First line nab-paclitaxel plus gemcitabine in elderly metastatic pancreatic patients: a good choice beyond age

Background

Nab-paclitaxel plus gemcitabine represents one of the standard regimens for first line treatment of metastatic pancreatic cancer (mPC). Few data are available on nab-paclitaxel plus gemcitabine in geriatric population. Our study aims to show whether this schedule can be feasible in the elderly as first-line treatment for mPC.

Methods

We retrospectively analyzed the data of 64 mPC patients (≥65 years old) treated according to the MPACT schedule.

Results

Median age was 69.5 years (range, 65-80 years); after a median of 5 cycles administered (range, 1-12), the most common adverse events (AEs) were grade 2 alopecia (46.9%), anemia (17.2%) and hypertransaminasemia (10.9%); all grades neutropenia occurred in 20.3% of pts. Global incidence of grade 3 and 4 toxicities were 26.5% and 0%, respectively, and no patients stopped treatment due to unacceptable toxicity. Stable disease (SD) was observed in 31.2% of patients, with a disease control rate (DCR) and overall response rate of 57.8% and 26.6%, respectively. After a median follow-up of 18 months, median progression free survival (PFS) was 8 months (95% CI: 6.3-9.6) and median OS was 12.0 months (95% CI: 8.4-15.6). The univariate analysis for overall survival (OS) showed that only ECOG performance status was an independent prognostic factor for survival.

Conclusions

Nab-paclitaxel plus gemcitabine schedule is feasible and effective in the "daily clinical practice" geriatric population.

Types of Erythropoietin-Stimulating Agents and Mortality among Patients Undergoing Hemodialysis

BACKGROUND

Despite the widespread use of erythropoietin-stimulating agents (ESAs) to treat anemia in patients undergoing hemodialysis, the relative mortality risks associated with use of different types of ESAs are unknown.

METHODS

To compare the mortality risk associated with use of short-acting ESAs versus long-acting ESAs, we conducted a nationwide cohort study of 194,698 hemodialysis patients in Japan who received either a short-acting (epoetin α/β or epoetin κ) or a long-acting (darbepoetin or epoetin β pegol) ESA. Study outcomes were 2-year all-cause and cause-specific mortality. In addition to Cox proportional hazards models, we performed an instrumental variable analysis in which facility-level long-acting ESA prescription rates were taken as the instrumental variable.

RESULTS

During the 2-year follow-up period, 31,557 deaths occurred. In a multivariable Cox model, long-acting ESA users had a 13% higher rate of deaths compared with short-acting ESA users, a significant difference (P<0.001). Similar results were obtained in other analyses. This difference in risk was pronounced among patients receiving high doses of ESA (for whom the adjusted 2-year number needed to harm for death was 30.8). Long-acting ESA use was associated with an increased rate of death from cardiovascular diseases, infection, and malignancies. In the instrumental variable analysis, long-acting ESA users remained at a significantly higher risk of death. Compared with anemic (hemoglobin 9.0-9.9 g/dl) short-acting ESA users, long-acting ESA users who achieved more optimal hemoglobin levels (10.0-10.9 g/dl) showed a higher mortality rate.

CONCLUSIONS

Among patients undergoing hemodialysis, use of long-acting ESAs might be associated with a higher risk of death than use of short-acting ESAs.

Erythropoietin inhibits SGK1-dependent TH17 induction and TH17-dependent kidney disease

IL-17-producing CD4+ cells (TH17) are pathogenically linked to autoimmunity including to autoimmune kidney disease. Erythropoietin's (EPO) newly recognized immunoregulatory functions and its predominant intra-renal source suggested that EPO physiologically regulates TH17 differentiation, thereby serving as a barrier to the development of autoimmune kidney disease. Using in vitro studies of human and murine cells and in vivo models, we show that EPO ligation of its receptor (EPO-R) on CD4+ T cells directly inhibits TH17 generation and promotes trans-differentiation of TH17 into IL-17-FOXP3+CD4+ T cells. Mechanistically, EPO/EPO-R ligation abrogates upregulation of SGK1 gene expression and blocks p38 activity to prevent SGK1 phosphorylation, thereby inhibiting RORC-mediated transcription of IL-17 and IL-23 receptor genes. In a murine model of TH17-dependent aristolochic acid (ArA)-induced, interstitial kidney disease associated with reduced renal EPO production, we demonstrate that transgenic EPO overexpression or recombinant EPO (rEPO) administration limits TH17 formation and clinical/histological disease expression. EPO/EPO-R ligations on CD4+ T cells abrogate, while absence of T cell-expressed EPO-R augments, TH17 induction and clinical/histological expression of pristane-induced glomerulonephritis (associated with decreased intrarenal EPO). rEPO prevents spontaneous glomerulonephritis and TH17 generation in MRL-lpr mice. Together, our findings indicate that EPO physiologically and therapeutically modulate TH17 cells to limit expression of TH17-associated autoimmune kidney disease.

Vasculogenic Mimicry Formation Is Associated with Erythropoietin Expression but Not with Erythropoietin Receptor Expression in Cervical Squamous Cell Carcinoma

Background

Vasculogenic mimicry (VM), as an endothelium-independent cancer microcirculation, has been observed in many malignancies including cervical cancer. Erythropoietin (EPO) and erythropoietin receptor (EPO-R) could produce an angiogenic effect to promote cervical squamous cell carcinoma (CSCC) progression. However, the association between VM formation and EPO/EPO-R expression in CSCC is poorly explored.

Methods

Seventy-six paraffin-embedded CSCC samples, 25 high-grade squamous intraepithelial lesion (HSIL) samples, 20 low-grade squamous intraepithelial lesion (LSIL) samples, and 20 normal cervix samples were collected. Immunohistochemistry SP method was performed to detect EPO/EPO-R expression and CD31/periodic acid-Schiff (PAS) double staining was performed to detect VM formation. The associations of EPO/EPO-R and VM with clinicopathological parameters of CSCC were analyzed. The associations between VM formation and EPO/EPO-R expression were also analyzed.

Results

The positive expression rates of EPO and EPO-R were gradually increasing along the progression of normal cervix-LSIL-HSIL-CSCC sequence (P<0.05). EPO and EPO-R expression were not significantly associated with clinicopathological parameters of CSCC patients (P>0.05). VM was significantly associated with FIGO stage, lymphovascular space involvement, and lymph node metastasis (P<0.05). VM was positively associated with EPO expression (r=0.284, P<0.05) but was not associated with EPO-R expression (P>0.05).

Conclusion

These data suggest that increased EPO/EPO-R expression may play an important role in cervical carcinogenesis. EPO overexpression may promote VM formation in CSCC.

Pleiotropic effects of Erythropoietin. Influence of Erythropoietin on processes of mesenchymal stem cells differentiation

Structure and synthesis of Erythropoietin: Erythropoietin (EPO) is a glycoprotein hormone.

Recombinant Erythropoietin (Epoetin): Human recombinant erythropoietin is characterised as a factor which stimulates differentiation and proliferation of erythroid precursor cells, and as a tissue protective factor.

Anti-ischemic effects of recombinant Erythropoietin: Erythropoietin is one of the most perspective humoral agents which are involved in the preconditioning phenomenon.

Erythropoietin receptors and signal transduction pathways: Erythropoietin effects on cells through their interconnection with erythropoietin receptors, which triggers complex intracellular signal cascades, such as JAK2/STAT signaling pathway, phosphatidylinositol 3-kinase (PI3K), protein kinase C, mitogen-activated protein kinase (MAPK), and nuclear factor (NF)-κB signaling pathways.

Mechanisms of the effect of Erythropoietin on hematopoietic and non-hematopoietic cells and tissues: In addition to regulation of haemopoiesis, erythropoietin mediates bone formation as it has an effect on hematopoietic stem cells and osteoblastic niche, and this illustrates connection between the processes of haematopoiesis and osteopoiesis which take place in the red bone marrow.

The effect of Erythropoietin on mesenchymal stem cells and process of bone tissue formation: Erythropoietin promotes mesenchymal stem cells proliferation, migration and differentiation in osteogenic direction. The evidence of which is expression of bone phenotype by cells under the influence of EPO, including activation of bone specific transcription factors Runx2, osteocalcin and bone sialoprotein.

Conclusion: Erythropoietin has a pleiotropic effect on various types of cells and tissues. But the mechanisms which are involved in the process of bone tissue restoration via erythropoietin are still poorly understood.

Red blood cell transfusion and its alternatives in oncologic surgery-A critical evaluation

Although blood transfusions have been used for more than 100 years and their potential to save lives is indisputable, there is still limited data on medium- and long-term outcomes after hemotherapy. Until recently, red blood cell transfusions represented the most commonly employed treatment for cancer anemia. As transfusions have been related to worse patient outcome in oncologic surgery, preventive strategies and alternative treatment approaches in the perioperative setting are warranted. This review aims to evaluate the evidence concerning the impact of transfusion on the course of malignant diseases with a focus on oncologic surgery and to provide a bundle of measures to improve patient care. The perioperative period is pivotal in determining long-term cancer outcome. An increasingly recognized area for improvement during this highly sensitive period is the treatment of anemia for three main reasons: Firstly, anemia has been recognized as an independent predictor of poor prognosis in cancer patients. Secondly, anemia is largely undertreated. Thirdly and probably most importantly, anemia therapy relied and often still relies heavily on red blood cell (RBC) transfusions, which may be an often suboptimal stopgap treatment. Perioperative RBC transfusions should be kept to a minimum due to growing concerns regarding the associated risks, which this review tries to clarify by providing an update of recent literature. This review furthermore discusses treatments for anemia and provides best-practice approaches to improve perioperative management of oncology patients undergoing surgery.

Perinatal hypoxic-ischemic brain injury in large animal models: Relevance to human neonatal encephalopathy

Perinatal hypoxia-ischemia resulting in death or lifelong disabilities remains a major clinical disorder. Neonatal models of hypoxia-ischemia in rodents have enhanced our understanding of cellular mechanisms of neural injury in developing brain, but have limitations in simulating the range, accuracy, and physiology of clinical hypoxia-ischemia and the relevant systems neuropathology that contribute to the human brain injury pattern. Large animal models of perinatal hypoxia-ischemia, such as partial or complete asphyxia at the time of delivery of fetal monkeys, umbilical cord occlusion and cerebral hypoperfusion at different stages of gestation in fetal sheep, and severe hypoxia and hypoperfusion in newborn piglets, have largely overcome these limitations. In monkey, complete asphyxia produces preferential injury to cerebellum and primary sensory nuclei in brainstem and thalamus, whereas partial asphyxia produces preferential injury to somatosensory and motor cortex, basal ganglia, and thalamus. Mid-gestational fetal sheep provide a valuable model for studying vulnerability of progenitor oligodendrocytes. Hypoxia followed by asphyxia in newborn piglets replicates the systems injury seen in term newborns. Efficacy of post-insult hypothermia in animal models led to the success of clinical trials in term human neonates. Large animal models are now being used to explore adjunct therapy to augment hypothermic neuroprotection.

Effects of recombinant human erythropoietin on cognition and neural activity in remitted patients with mood disorders and first-degree relatives of patients with psychiatric disorders: a study protocol for a randomized controlled trial

Background

Bipolar disorder (BD) and unipolar disorder (UD) are associated with cognitive deficits and abnormal neural activity in a “cognitive control network.” There is an increased prevalence of cognitive dysfunction in psychiatric patients’ first-degree relatives, which constitutes a risk factor for psychiatric illness onset. However, there is no treatment with enduring pro-cognitive efficacy. We found preliminary evidence for beneficial effects of eight weekly doses of recombinant human erythropoietin (EPO) on cognition in BD in a recent randomized controlled trial (RCT). The present RCT consists of two sub-studies that extend our previous work by investigating important novel aspects: (1) the effects of 12 weekly doses of EPO on cognition in first-degree relatives of patients with BD, UD, or schizophrenia; and (2) the effects of extending the treatment schedule from 8 to 12 weeks in remitted patients with BD or UD; and (3) assessment of early treatment-associated neural activity changes that may predict cognitive improvement.

Methods

The trial comprises two parallel sub-studies with randomized, controlled, double-blinded, parallel group designs. First-degree relatives (sub-study 1; n = 52) and partially or fully remitted patients with BD or UD (sub-study 2; n = 52) with objectively verified cognitive dysfunction are randomized to receive weekly high-dose EPO (40,000 IU/mL) or placebo (saline) infusions for 12 weeks. Assessments of cognition and mood are conducted at baseline, after two weeks of treatment, after treatment completion, and at six-month follow-up. Functional magnetic resonance imaging (fMRI) is conducted at baseline and after two weeks of treatment. Psychosocial function is assessed at baseline, after treatment completion and six-month follow-up. The primary outcome is change in a cognitive composite score of attention, verbal memory, and executive functions. Statistical power of ≥ 80% is reached to detect a clinically relevant between-group difference by including 52 first-degree relatives and 52 patients with BD or UD, respectively. Behavioral data are analyzed with an intention-to-treat approach using mixed models. fMRI data are analyzed with the FMRIB Software Library.

Discussion

If this trial reveals pro-cognitive effects of EPO, this may influence future treatment of mood disorders and/or preventive strategies in at-risk populations. The fMRI analyses may unravel key neurobiological targets for pro-cognitive treatment.

Trial registration

ClinicalTrials.gov, NCT03315897. Registered on 20 October 2017.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-2995-7) contains supplementary material, which is available to authorized users.

Oxidative stress, eryptosis and anemia: a pivotal mechanistic nexus in systemic diseases

The average lifespan of circulating erythrocytes usually exceeds hundred days. Prior to that, however, erythrocytes may be exposed to oxidative stress in the circulation which could cause injury and trigger their suicidal death or eryptosis. Oxidative stress activates Ca²⁺ -permeable nonselective cation channels in the cell membrane, thus, stimulating Ca²⁺ entry and subsequent cell membrane scrambling resulting in phosphatidylserine exposure and activation of Ca²⁺ -sensitive K⁺ channels leading to K⁺ exit, hyperpolarization, Cl^- exit, and ultimately cell shrinkage due to loss of KCl and osmotically driven water. While the mechanistic link between oxidative stress and anemia remains ill-defined, several diseases such as diabetes, hepatic failure, malignancy, chronic kidney disease and inflammation have been identified to display both increased oxidative stress as well as eryptosis. Recent compelling evidence suggests that oxidative stress is an important perpetrator in accelerating erythrocyte loss in different systemic conditions and an underlying mechanism for anemia associated with these pathological states. In the present review, we discuss the role of oxidative stress in reducing erythrocyte survival and provide novel insights into the possible use of antioxidants as putative antieryptotic and antianemic agents in a variety of systemic diseases.

Erythropoiesis and chronic kidney disease-related anemia: From physiology to new therapeutic advancements

Erythropoiesis is triggered by hypoxia and is strictly regulated by hormones, growth factors, cytokines, and vitamins to ensure an adequate oxygen delivery to all body cells. Abnormalities in one or more of these factors may induce different kinds of anemia requiring different treatments. A key player in red blood cell production is erythropoietin. It is a glycoprotein hormone, mainly produced by the kidneys, that promotes erythroid progenitor cell survival and differentiation in the bone marrow and regulates iron metabolism. A deficit in erythropoietin synthesis is the main cause of the normochromic normocytic anemia frequently observed in patients with progressive chronic kidney disease. The present review summarizes the most recent findings about each step of the erythropoietic process, going from the renal oxygen sensing system to the cascade of events induced by erythropoietin through its own receptor in the bone marrow. The paper also describes the new class of drugs designed to stabilize the hypoxia-inducible factor by inhibiting prolyl hydroxylase, with a discussion about their metabolism, disposition, efficacy, and safety. According to many trials, these drugs seem able to simulate tissue hypoxia and then stimulate erythropoiesis in patients affected by renal impairment. In conclusion, the in-depth investigation of all events involved in erythropoiesis is crucial to understand anemia pathophysiology and to identify new therapeutic strategies, in an attempt to overcome the potential side effects of the commonly used erythropoiesis-stimulating agents.

Activation of the β-common receptor by erythropoietin impairs acetylcholine-mediated vasodilation in mouse mesenteric arterioles

Clinically, erythropoietin (EPO) is known to increase systemic vascular resistance and arterial blood pressure. However, EPO stimulates the production of the potent vasodilator, nitric oxide (NO), in culture endothelial cells. The mechanism by which EPO causes vasoconstriction despite stimulating NO production may be dependent on its ability to activate two receptor complexes, the homodimeric EPO (EPOR2 ) and the heterodimeric EPOR/β-common receptor (βCR). The purpose of this study was to investigate the contribution of each receptor to the vasoactive properties of EPO. First-order, mesenteric arteries were isolated from 16-week-old male C57BL/6 mice, and arterial function was studied in pressure arteriographs. To determine the contribution of each receptor complex, EPO-stimulating peptide (ESP), which binds and activates the heterodimeric EPOR/βCR complex, and EPO, which activates both receptors, were added to the arteriograph chamber 20 min prior to evaluation of endothelium-dependent (acetylcholine, bradykinin, A23187) and endothelium-independent (sodium nitroprusside) vasodilator responses. Only ACh-induced vasodilation was impaired in arteries pretreated with EPO or ESP. EPO and ESP pretreatment abolished ACh-induced vasodilation by 100% and 60%, respectively. EPO and ESP did not affect endothelium-independent vasodilation by SNP. Additionally, a novel βCR inhibitory peptide (βIP), which was computationally developed, prevented the impairment of acetylcholine-induced vasodilation by EPO and ESP, further implicating the EPOR/βCR complex. Last, pretreatment with either EPO or ESP did not affect vasoconstriction by phenylephrine and KCl. Taken together, these findings suggest that acute activation of the heterodimeric EPOR/βCR in endothelial cells leads to a selective impairment of ACh-mediated vasodilator response in mouse mesenteric resistance arteries.

Erythropoietin as an add-on treatment for cognitive side effects of electroconvulsive therapy: a study protocol for a randomized controlled trial

Background

Electroconvulsive therapy (ECT) is the most effective treatment for severe depression, but its use is impeded by its cognitive side effects. Novel treatments that can counteract these side effects may therefore improve current treatment strategies for depression. The present randomized trial investigates (1) whether short-term add-on treatment with erythropoietin (EPO) can reduce the cognitive side -effects of ECT and (2) whether such effects are long-lasting. Further, structural and functional magnetic resonance imaging (MRI) will be used to explore the neural underpinnings of such beneficial effects of EPO. Finally, the trial examines whether potential protective effects of EPO on cognition are accompanied by changes in markers of oxidative stress, inflammation, and neuroplasticity.

Methods/design

The trial has a double-blind, randomized, placebo-controlled, parallel group design. Patients with unipolar or bipolar disorder with current moderate to severe depression referred to ECT (N = 52) are randomized to receive four high-dose infusions of EPO (40,000 IU/ml) or placebo (saline). The first EPO/saline infusion is administered within 24 h before the first ECT. The following three infusions are administered at weekly intervals immediately after ECT sessions 1, 4, and 7. Cognition assessments are conducted at baseline, after the final EPO/saline infusion (3 days after eight ECT sessions), and at a 3 months follow-up after ECT treatment completion. The neuronal substrates for potential cognitive benefits of EPO are investigated with structural and functional MRI after the final EPO/saline infusion. The primary outcome is change from baseline to after EPO treatment (3 days after eight ECT sessions) in a cognitive composite score spanning attention, psychomotor speed, and executive functions. With a sample size of N = 52 (n = 26 per group), we have ≥ 80% power to detect a clinically relevant between-group difference in the primary outcome measure at an alpha level of 5% (two-sided test). Behavioral, mood, and blood-biomarker data will be analyzed using repeated measures analysis of covariance. Functional MRI data will be preprocessed and analyzed using the FMRIB Software Library.

Discussion

If EPO is found to reduce the cognitive side effects of ECT, this could have important implications for future treatment strategies for depression and for the scientific understanding of the neurobiological etiology of cognitive dysfunction in patients treated with ECT.

Trial registration

ClinicalTrials.gov, NCT03339596. Registered on 10 November 2017.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-2627-2) contains supplementary material, which is available to authorized users.

Neuronal erythropoietin overexpression is protective against kanamycin-induced hearing loss in mice

Aminoglycosides have detrimental effects on the hair cells of the inner ear, yet these agents indisputably are one of the cornerstones in antibiotic therapy. Hence, there is a demand for strategies to prevent aminoglycoside-induced ototoxicity, which are not available today. In vitro data suggests that the pleiotropic growth factor erythropoietin (EPO) is neuroprotective against aminoglycoside-induced hair cell loss. Here, we use a mouse model with EPO-overexpression in neuronal tissue to evaluate whether EPO could also in vivo protect from aminoglycoside-induced hearing loss. Auditory brainstem response (ABR) thresholds were measured in 12-weeks-old mice before and after treatment with kanamycin for 15 days, which resulted in both C57BL/6 and EPO-transgenic animals in a high-frequency hearing loss. However, ABR threshold shifts in EPO-transgenic mice were significantly lower than in C57BL/6 mice (mean difference in ABR threshold shift 13.6 dB at 32 kHz, 95% CI 3.8-23.4 dB, p = 0.003). Correspondingly, quantification of hair cells and spiral ganglion neurons by immunofluorescence revealed that EPO-transgenic mice had a significantly lower hair cell and spiral ganglion neuron loss than C57BL/6 mice. In conclusion, neuronal overexpression of EPO is protective against aminoglycoside-induce hearing loss, which is in accordance with its known neuroprotective effects in other organs, such as the eye or the brain.

Enhanced eryptosis contributes to anemia in lung cancer patients

Objectives

Anemia is a common complication of malignancy, which could result from either compromised erythropoiesis or decreased lifespan of circulating erythrocytes. Premature suicidal erythrocyte death, characterized by cell shrinkage and phosphatidylserine (PS) externalization, decreases erythrocyte lifespan and could thus cause anemia. Here, we explored whether accelerated eryptosis participates in the pathophysiology of anemia associated with lung cancer (LC) and its treatment.

Methods

Erythrocytes were drawn from healthy volunteers and LC patients with and without cytostatic treatment. PS exposure (annexin V-binding), cell volume (forward scatter), cytosolic Ca²⁺ (Fluo3 fluorescence), reactive oxygen species (ROS) production (DCFDA fluorescence) and ceramide formation (anti-ceramide antibody) were determined by flow cytometry.

Results

Hemoglobin concentration and hematocrit were significantly lower in LC patients as compared to healthy controls, even though reticulocyte number was higher in LC (3.0±0.6%) than in controls (1.4±0.2%). The percentage of PS-exposing erythrocytes was significantly higher in LC patients with (1.4±0.1%) and without (1.2±0.3%) cytostatic treatment as compared to healthy controls (0.6±0.1%). Erythrocyte ROS production and ceramide abundance, but not Fluo3 fluorescence, were significantly higher in freshly drawn erythrocytes from LC patients than in freshly drawn erythrocytes from healthy controls. PS exposure of erythrocytes drawn from healthy volunteers was significantly more pronounced following incubation in plasma from LC patients than following incubation in plasma from healthy controls.

Conclusion

Anemia in LC patients with and without cytostatic treatment is paralleled by increased eryptosis, which is triggered, at least in part, by increased oxidative stress and ceramide formation.

99m Tc-labeled rHuEpo for imaging of the erythropoietin receptor in tumors

To analyze erythropoietin receptor (EpoR) status in tumors, recombinant human erythropoietin (rHuEpo) was labeled with ^99m Tc by ^99m Tc-centered 1-pot synthesis, resulting in high radiochemical purity, stability, and biological activity. Both in vitro cell culture experiments and biodistribution studies of normal rats demonstrated successful EpoR targeting. The biodistribution of labeled rHuEpo in a NCI-H1975 xenograft model showed tumor accumulation (tumor-to-muscle ratio, 4.27 ± 1.77), confirming the expression of active EpoR in tumors. Thus, as a novel single positron emission computerized tomography tracer for the imaging of EpoR expression in vivo, ^99m Tc-rHuEpo is effective for exploring the role of EpoR in cancer growth, metastasis and angiogenesis.

Harms of off-label erythropoiesis-stimulating agents for critically ill people

BACKGROUND

Anaemia is a common problem experienced by critically-ill people. Treatment with erythropoiesis-stimulating agents (ESAs) has been used as a pharmacologic strategy when the blunted response of endogenous erythropoietin has been reported in critically-ill people. The use of ESAs becomes more important where adverse clinical outcomes of transfusing blood products is a limitation. However, this indication for ESAs is not licensed by regulatory authorities and is called off-label use. Recent studies concern the harm of ESAs in a critical care setting.

OBJECTIVES

To focus on harms in assessing the effects of erythropoiesis-stimulating agents (ESAs), alone or in combination, compared with placebo, no treatment or a different active treatment regimen when administered off-label to critically-ill people.

SEARCH METHODS

We conducted a systematic search of the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, PsycINFO via OvidSP, CINAHL, all evidence-based medicine (EBM) reviews including IPA and SCI-Expanded, Conference Proceedings Citation Index- Science, BIOSIS Previews and TOXLINE up to February 2017. We also searched trials registries, checked reference lists of relevant studies and tracked their citations by using SciVerse Scopus.

SELECTION CRITERIA

We considered randomized controlled trials (RCTs) and controlled observational studies, which compared scheduled systemic administration of ESAs versus other effective interventions, placebo or no treatment in critically-ill people.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened and evaluated the eligibility of retrieved records, extracted data and assessed the risks of bias and quality of the included studies. We resolved differences in opinion by consensus or by involving a third review author. We assessed the evidence using GRADE and created a 'Summary of findings' table. We used fixed-effect or random-effects models, depending on the heterogeneity between studies. We fitted three-level hierarchical Bayesian models to calculate overall treatment effect estimates.

MAIN RESULTS

Of the 27,865 records identified, 39 clinical trials and 14 observational studies, including a total of 945,240 participants, were eligible for inclusion. Five studies are awaiting classification. Overall, we found 114 adverse events in 33 studies (30 RCTs and three observational studies), and mortality was reported in 41 studies (32 RCTs and nine observational studies). Most studies were at low to moderate risk of bias for harms outcomes. However, overall harm assessment and reporting were of moderate to low quality in the RCTs, and of low quality in the observational studies. We downgraded the GRADE quality of evidence for venous thromboembolism and mortality to very low and low, respectively, because of risk of bias, high inconsistency, imprecision and limitations of study design.It is unclear whether there is an increase in the risk of any adverse events (Bayesian risk ratio (RR) 1.05, 95% confidence interval (CI) 0.93 to 1.21; 3099 participants; 9 studies; low-quality evidence) or venous thromboembolism (Bayesian RR 1.04, 95% CI 0.70 to 1.41; 18,917 participants; 18 studies; very low-quality evidence).There was a decreased risk of mortality with off-label use of ESAs in critically-ill people (Bayesian RR 0.76, 95% CI 0.61 to 0.92; 930,470 participants; 34 studies; low-quality evidence).

AUTHORS' CONCLUSIONS

Low quality of evidence suggests that off-label use of ESAs may reduce mortality in a critical care setting. There was a lack of high-quality evidence about the harm of ESAs in critically-ill people. The information for biosimilar ESAs is less conclusive. Most studies neither evaluated ESAs' harm as a primary outcome nor predefined adverse events. Any further studies of ESA should address the quality of evaluating, recording and reporting of adverse events.

Overexpression of the erythropoietin receptor in RAMA 37 breast cancer cells alters cell growth and sensitivity to tamoxifen

Erythropoietin (EPO) is the main regulator of erythropoiesis, and its receptor (EPOR) is expressed in various tissues, including tumors. Expression of EPOR in breast cancer tissue has been shown to correlate with expression of the estrogen receptor (ER). However, EPOR promotes proliferation in an EPO-independent manner. In patients with breast cancer, EPOR is associated with impaired tamoxifen response in ER-positive tumors, but not in ER-negative tumors. Furthermore, a positive correlation between EPOR/ER status and increased local cancer recurrence has been demonstrated, and EPOR expression is associated with G-protein coupled ER (GPER). Herein, we assessed the effects of EPOR on cell physiology and tamoxifen response in the absence of EPO stimulation using two cell lines that differ only in their EPOR expression status: RAMA 37 cells (low EPOR expression) and RAMA 37-28 cells (high EPOR expression). Alterations in cell growth, morphology, response to tamoxifen cytotoxicity, and EPOR-activated signal transduction were observed. RAMA 37 cells showed higher proliferation capacity without tamoxifen treatment, while RAMA 37-28 cells were more resistant to tamoxifen and proliferated more rapidly in the presence of tamoxifen. EPOR overexpression induced cell-morphology changes upon tamoxifen treatment, which resulted in the production of cell protrusions and subsequent cell death. Short-term treatment with tamoxifen (6 h) prompted RAMA 37 cells to acquired longer protrusions than RAMA 37-28 cells, which indicated a pre-apoptotic stage. Furthermore, prolonged treatment with tamoxifen (72 h) caused a greater reduction in RAMA 37 cell numbers, which indicated a higher rate of cell death. RAMA 37-28 cells showed prolonged activation of AKT signaling. We propose sustained AKT phosphorylation in EPOR-overexpressing cells as a mechanism that can lead to EPOR-induced tamoxifen resistance.

Erythropoietin Induces an Epithelial to Mesenchymal Transition-Like Process in Mammary Epithelial Cells MCF10A

Anemia is associated with chemotherapy treatment in cancer patients. Erythropoietin (EPO) has been used to treat anemia of cancer patients, because it stimulates erythropoiesis. However, treatment of breast cancer patients with EPO has been associated with poor prognosis and decrease of survival. Epithelial to mesenchymal transition (EMT) is a process by which epithelial cells are transdifferentiated to a mesenchymal state. It has been implicated in tumor progression, because epithelial cells acquire the capacity to execute the multiple steps of invasion/metastasis process. However, the role of EPO on EMT process in human mammary epithelial cells has not been studied. In the present study, we demonstrate that EPO promotes a decrease of E-cadherin expression, an increase of N-cadherin, vimentin, and Snail2 expression, activation of FAK and Src kinases and an increase of MMP-2 and MMP-9 secretions. Moreover, EPO induces an increase of NFκB DNA binding activity, an increase of binding of p50 and p65 NFκB subunits to Snail1 promoter, migration, and invasion in mammary non-tumorigenic epithelial cells MCF10A. In summary, these findings demonstrate, for the first time, that EPO induces an EMT-like process in mammary non-tumorigenic epithelial cells. J. Cell. Biochem. 118: 2983-2992, 2017. © 2017 Wiley Periodicals, Inc.

Erythropoietin Promotes Glioblastoma via miR-451 Suppression

Erythropoietin (EPO) is an erythropoiesis stimulating growth factor and hormone. EPO has been widely used in the treatment of chronic renal failure, cancer, and chemotherapy-related anemia for three decades. However, many clinical trials showed that EPO treatment may be associated with tumorigenesis and cancer progression. EPO is able to cross blood-brain barriers, and this may lead to an increased possibility of central nervous system tumors such as glioblastoma. Indeed, EPO promotes glioblastoma growth and invasion in animal studies. Additionally, EPO increases glioblastoma cell survival, proliferation, migration, invasion, and chemoresistancy in vitro. However, the exact mechanisms of cancer progression induced by EPO treatment are not fully understood. Posttranscriptional gene regulation through microRNAs may contribute to EPO's cellular and biological effects in tumor progression. Here, we aimed to study whether tumor suppressive microRNA, miR-451, counteracts the positive effects of EPO on U87 human glioblastoma cell line. Migration and invasion were evaluated by scratch assay and transwell invasion assay, respectively. We found that EPO decreased basal miR-451 expression and increased cell proliferation, migration, invasion, and cisplatin chemoresistancy in vitro. miR-451 overexpression by transfection of its mimic significantly reversed these effects. Furthermore, ectopic expression of miR-451 inhibited expression of its own target genes, such as metalloproteinases-2 and -9, which are stimulated by EPO treatment and involved in carcinogenesis processes, especially invasion. These findings suggest that miR-451 mimic delivery may be useful as adjuvant therapy in addition to chemotherapy and anemia treatment by EPO and should be tested in experimental glioblastoma models.