Erythropoietin promotes the growth of tumors lacking its receptor and decreases survival of tumor-bearing mice by enhancing angiogenesis

Prognostic impact of erythropoietin-stimulating agent use during front-line chemotherapy in patients with ovarian cancer: A Korean multicenter cohort study

OBJECTIVE

To evaluate whether treatment with erythropoiesis-stimulating agents (ESAs) for chemotherapy-induced anemia affects progression-free survival (PFS) in patients receiving front-line chemotherapy following surgery for ovarian cancer (OC).

METHODS

We retrospectively reviewed all consecutive patients who received front-line chemotherapy after surgery between 2013 and 2019 at six institutions. The patients were divided according to the use of ESAs during front-line chemotherapy. The primary endpoint was PFS. The secondary endpoint was the occurrence of thromboembolism. Propensity score matching (PSM) analysis was used to compare survival between matched cohorts.

RESULTS

Overall, 2147 patients (433 receiving ESA and 1714 for no-ESA) were identified, with a median follow-up of 44.0 months. The ESA group showed a significantly higher proportion of stage III/IV disease (81.8% vs 61.1%; P < 0.001) and postoperative gross residual disease (32.3% vs 21.2%; P < 0.001) than the no-ESA group. In the multivariable Cox regression analysis, the use of ESAs did not affect PFS (adjusted hazard ratio, 1.03; 95% confidence interval [CI]: 0.89-1.20; P = 0.661). The incidence of thromboembolism was 10.2% in the ESA group and 4.6% in the no-ESA group (adjusted odds ratio, 6.58; 95% CI: 3.26-13.28; P < 0.001). When comparing the well-matched cohorts after PSM, PFS did not differ between the ESA (median PFS 23.5 months) and no-ESA groups (median PFS 22.2 months) (P = 0.540, log-rank test).

CONCLUSIONS

The use of ESAs during front-line chemotherapy did not negatively affect PFS in patients with OC after surgery but increased the risk of thromboembolism.

Cytoprotective effects of erythropoietin: What about the lung?

Erythropoietin (Epo) is a pleiotropic cytokine, essential for erythropoiesis. Epo and its receptor (Epo-R) are produced by several tissues and it is now admitted that Epo displays other physiological functions than red blood cell synthesis. Indeed, Epo provides cytoprotective effects, which consist in prevention or fight against pathological processes. This perspective article reviews the various protective effects of Epo in several organs and tries to give a proof of concept about its effects in the lung. The tissue-protective effects of Epo could be a promising approach to limit the symptoms of acute and chronic lung diseases.

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.

Rational engineering of an erythropoietin fusion protein to treat hypoxia

Erythropoietin enhances oxygen delivery and reduces hypoxia-induced cell death, but its pro-thrombotic activity is problematic for use of erythropoietin in treating hypoxia. We constructed a fusion protein that stimulates red blood cell production and neuroprotection without triggering platelet production, a marker for thrombosis. The protein consists of an anti-glycophorin A nanobody and an erythropoietin mutant (L108A). The mutation reduces activation of erythropoietin receptor homodimers that induce erythropoiesis and thrombosis, but maintains the tissue-protective signaling. The binding of the nanobody element to glycophorin A rescues homodimeric erythropoietin receptor activation on red blood cell precursors. In a cell proliferation assay, the fusion protein is active at 10-14 M, allowing an estimate of the number of receptor-ligand complexes needed for signaling. This fusion protein stimulates erythroid cell proliferation in vitro and in mice, and shows neuroprotective activity in vitro. Our erythropoietin fusion protein presents a novel molecule for treating hypoxia.

Therapeutic strategies for enhancing angiogenesis in wound healing

The enhancement of wound healing has been a goal of medical practitioners for thousands of years. The development of chronic, non-healing wounds is a persistent medical problem that drives patient morbidity and increases healthcare costs. A key aspect of many non-healing wounds is the reduced presence of vessel growth through the process of angiogenesis. This review surveys the creation of new treatments for healing cutaneous wounds through therapeutic angiogenesis. In particular, we discuss the challenges and advancement that have been made in delivering biologic, pharmaceutical and cell-based therapies as enhancers of wound vascularity and healing.

Methylation of the first exon in the erythropoietin receptor gene does not correlate with its mRNA and protein level in cancer cells

Background

Erythropoietin receptor (EPOR) is a functional membrane-bound cytokine receptor. Erythropoietin (EPO) represents an important hematopoietic factor for production, maturation and differentiation of erythroid progenitors. In non-hematopoietic tissue, EPO/EPOR signalization could also play cytoprotective and anti-apoptotic role. Several studies identified pro-stimulating EPO/EPOR effects in tumor cells; however, numerous studies opposed this fact due to the usage of unspecific EPOR antibodies and thus potential absence or very low levels of EPOR in tumor cells. It seems that this problem is more complex and therefore we have decided to focus on EPOR expression at several levels such as the role of methylation in the regulation of EPOR expression, identification of possible EPOR transcripts and the presence of EPOR protein in selected tumor cells.

Methods

Methylation status was analysed by bisulfite conversion reaction, PCR and sequencing. The expression of EPOR was monitored by quantitative RT-PCR and western blot analysis.

Results

In this study we investigated the methylation status of exon 1 of EPOR gene in selected human cancer cell lines. Our results indicated that CpGs methylation in exon 1 do not play a significant role in the regulation of EPOR transcription. However, methylation status of EPOR exon 1 was cell type dependent. We also observed the existence of two EPOR splice variants in human ovarian adenocarcinoma cell line - A2780 and confirmed the expression of EPOR protein in these cells using specific A82 anti-EPOR antibody.

Conclusion

We outlined the methylation status of all selected cancer cell lines in exon 1 of EPOR gene and these results could benefit future investigations. Moreover, A82 antibody confirmed our previous results demonstrating the presence of functional EPOR in human ovarian adenocarcinoma A2780 cells.

Role of erythropoietin in the angiogenic activity of bone marrow endothelial cells of MGUS and multiple myeloma patients

Increasing evidences suggest several biological roles for erythropoietin and its receptor (Epo and EpoR), unrelated to erythropoiesis, including angiogenesis. Here, we detected the expression of EpoR in bone marrow-derived endothelial cells from monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma (MM) patients (MGECs and MMECs, respectively) and assessed whether Epo plays a role in MGECs- and MMECs-mediated angiogenesis. We show that EpoR is expressed by both MGECs and MMECs even though at a higher level in the first ones. Both EC types respond to rHuEpo in terms of cell proliferation, whereas other responses, including activation of JAK2/STAT5 and PI3K/Akt pathways, cell migration and capillarogenesis are enhanced by Epo in MGECs, but not in MMECs. In addition, the conditioned media of both Epo-treated cells induce a strong angiogenic response in vivo in the chorioallantoic membrane assay, comparable to that of vascular endothelial growth factor (VEGF). Overall, these data highlight the effect of Epo on MGECs- and MMECs-mediated angiogenesis: MGECs are more responsive to Epo treatment than MMECs, probably because over-angiogenic phenotype of MMECs is already activated by their autocrine/paracrine loops occurring in the “angiogenic switch” from MGUS.

Erythropoietin and Its Angiogenic Activity

Erythropoietin (EPO) is the main hematopoietic hormone acting on progenitor red blood cells via stimulation of cell growth, differentiation, and anti-apoptosis. However, its receptor (EPOR) is also expressed in various non-hematopoietic tissues, including endothelium. EPO is a pleiotropic growth factor that exhibits growth stimulation and cell/tissue protection on numerous cells and tissues. In this article we review the angiogenesis potential of EPO on endothelial cells in heart, brain, and leg ischemia, as well as its role in retinopathy protection and tumor promotion. Furthermore, the effect of EPO on bone marrow and adipose tissue is also discussed.

Erythropoietin increases macrophage-mediated T cell suppression

Erythropoietin (EPO), used to treat anemia in cancer patients, has been reported to accelerate tumor progression and increase mortality. Research of the mechanism for this effect has focused upon EPOR expression by tumor cells. We model the high macrophage to lymphocyte ratio found in tumor microenvironments (TMEs) by culturing peritoneal cavity (PerC) cells that naturally have a high macrophage to T cell ratio. Following TCR ligation, C57BL/6J PerC T cell proliferation is suppressed due to IFNγ-triggered inducible nitric oxide synthase (iNOS) expression. EPO was tested in the PerC culture model and found to increase T cell suppression. This effect could be abrogated by inhibiting iNOS by enzyme inhibition, genetic ablation, or blocking IFNγ signaling. Flow cytometry revealed the EPOR on CD11b(+)F4/80(+) macrophages. These results suggest that EPO could increase T cell suppression in the TME by acting directly on macrophages.

Far-western blotting as a solution to the non-specificity of the anti-erythropoietin receptor antibody

The erythropoietin receptor (EpoR) is a member of the cytokine receptor family. The interaction between erythropoietin (Epo) and EpoR is important for the production and maturation of erythroid cells, resulting in the stimulation of hematopoiesis. The fact that EpoR was also detected in neoplastic cells has opened the question about the relevance of anemia treatment with recombinant Epo in cancer patients. Numerous studies have reported pro-stimulating and anti-apoptotic effects of Epo in cancer cells, thus demonstrating EpoR functionality in these cells. By contrast, a previous study claims the absence of EpoR in tumor cells. This apparent discrepancy is based, according to certain authors, on the use of non-specific anti-EpoR antibodies. With the aim of bypassing the direct detection of EpoR with an anti-EpoR antibody, the present authors propose a far-western blot methodology, which in addition, confirms the interaction of Epo with EpoR. Applying this technique, the presence of EpoR and its interaction with Epo in human ovarian adenocarcinoma A2780 and normal human umbilical vein endothelial cells was confirmed. Furthermore, modified immunoprecipitation of EpoR followed by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry analysis confirmed a 57 kDa protein as a human Epo-interacting protein in both cell lines.

Darbepoetin-α Promotes Cell Proliferation in Established Extrahepatic Colorectal Tumors after Major Hepatectomy

BACKGROUND

The glycoprotein hormone erythropoietin and its analogue darbepoetin-α (DPO) have been shown to reduce the risk of acute liver failure after major hepatectomy. However, previous experimental studies have also shown that DPO significantly enhances neovascularization and tumor cell proliferation in established colorectal liver metastasis in hepatectomized and nonhepatectomized mice. The present study now analyzes whether DPO influences cell proliferation and migration as well as vascularization and growth of established colorectal metastasis at extrahepatic sites after major hepatectomy.

METHODS

GFP-transfected CT26.WT colorectal cancer cells were implanted into dorsal skinfold chambers of syngeneic BALB/c mice. Five days after tumor cell implantation, the animals received a single dose of DPO (10 µg/kg body weight) or phosphate-buffered saline solution (PBS) intravenously. Additional animals received a 70% hepatectomy and DPO or PBS treatment. Tumor vascularization and growth as well as tumor cell migration, proliferation and apoptosis were studied repetitively over 14 days using intravital fluorescence microscopy, histology and immunohistochemistry.

RESULTS

DPO did not influence tumor cell migration and apoptosis. In addition, DPO did not stimulate tumor cell infiltration or vascularization; however, significantly increased tumor cell proliferation was detected in hepatectomized animals.

CONCLUSION

DPO increases cell proliferation in established extrahepatic colorectal metastases after major hepatectomy. Thus, DPO may not be recommended to stimulate regeneration of the remnant liver after major hepatectomy for colorectal liver metastasis.

Erythropoietin Stimulates Tumor Growth via EphB4

While recombinant human erythropoietin (rhEpo) has been widely used to treat anemia in cancer patients, concerns about its adverse effects on patient survival have emerged. A lack of correlation between expression of the canonical EpoR and rhEpo's effects on cancer cells prompted us to consider the existence of an alternative Epo receptor. Here, we identified EphB4 as an Epo receptor that triggers downstream signaling via STAT3 and promotes rhEpo-induced tumor growth and progression. In human ovarian and breast cancer samples, expression of EphB4 rather than the canonical EpoR correlated with decreased disease-specific survival in rhEpo-treated patients. These results identify EphB4 as a critical mediator of erythropoietin-induced tumor progression and further provide clinically significant dimension to the biology of erythropoietin.

Aberrant expression of erythropoietin in uterine leiomyoma: implications in tumor growth

OBJECTIVE

Myomatous erythrocytosis syndrome is a rare complication of uterine leiomyoma caused by erythropoietin (EPO) that is produced by tumor cells. We assessed the EPO expression in leiomyomas and investigated the effects of EPO on the tumor growth.

STUDY DESIGN

Tissue samples were collected from 114 patients with uterine leiomyomas who underwent myomectomy or hysterectomy in Yokohama City University Hospital. From 17 patients, the corresponding normal myometrium was also collected. All samples were analyzed for EPO messenger RNA (mRNA) expression by real-time reverse transcription-polymerase chain reaction. EPO protein expression was determined by an enzyme-linked immunosorbent assay. The relationships between EPO expression and clinicopathological features were retrospectively analyzed using the patients' charts. Blood vessel density and maturity were assessed using hematoxylin-eosin staining and CD34 immunohistochemistry.

RESULTS

EPO mRNA expression was detected in 108 of 114, or 95%, of the leiomyomas. The mean EPO mRNA expression in the leiomyoma was higher than the corresponding normal myometrium (3836 ± 4122 vs 1455 ± 2141; P = .025 by Wilcoxon rank test). The EPO mRNA expression in the leiomyomas varied extensively among samples, ranging from undetectable levels to 18-fold above the mean EPO mRNA of normal myometrium. EPO protein production was observed concomitant with mRNA expression. A positive correlation of leiomyoma size and EPO mRNA expression was shown by Spearman rank correlation coefficient (ρ = 0.294; P = .001), suggesting the involvement of EPO in leiomyoma growth. The blood vessel maturity was also significantly increased in EPO-producing leiomyomas (high vessel maturity in high vs low EPO group: 67% vs 20%; P = .013 by Fisher exact test).

CONCLUSION

This report demonstrates that EPO is produced in most of conventional leiomyomas and supports a model in which EPO accelerates tumor growth, possibly by inducing vessel maturity. Our study suggests one possible mechanism by which some uterine leiomyomas reach a large size, and the understanding of EPO expression patterns in these tumors may be useful for management of the patients with leiomyomas.

Erythropoietin improves the accumulation and therapeutic effects of carboplatin by enhancing tumor vascularization and perfusion

Recombinant human erythropoietin (rhuEpo) is currently under debate for the treatment of chemotherapy-induced anemia due to clinical trials showing adverse effects in Epo-treated patients and the discovery of the erythropoietin-receptor (EpoR) in tumor and endothelial cells. Here, using Epo-Cy5.5 as theranostic near-infrared fluorescent probe we analyzed the effects of rhuEpo as co-medication to carboplatin in non-small-cell-lung-cancer (NSCLC)-xenografts with different tumor cell EpoR-expression (H838 ~8-fold higher than A549). Nude mice bearing subcutaneous A549 and H838 NSCLC-xenografts received either only carboplatin or carboplatin and co-medication of rhuEpo in two different doses. Tumor sizes and relative blood volumes (rBV) were longitudinally measured by 3D-contrast-enhanced ultrasound (3D-US). Tumoral EpoR-levels were determined by combined fluorescence molecular tomography (FMT)/ micro computed tomography (µCT) hybrid imaging. We found that rhuEpo predominantly acted on the tumor endothelium. In both xenografts, rhuEpo co-medication significantly increased vessel densities, diameters and the amount of perfused vessels. Accordingly, rhuEpo induced EpoR-phoshorylation and stimulated proliferation of endothelial cells. However, compared with solely carboplatin-treated tumors, tumor growth was significantly slower in the groups co-medicated with rhuEpo. This is explained by the Epo-mediated vascular remodeling leading to improved drug delivery as obvious by a more than 2-fold higher carboplatin accumulation and significantly enhanced tumor apoptosis. In addition, co-medication of rhuEpo reduced tumor hypoxia and diminished intratumoral EpoR-levels which continuously increased during carboplatin (Cp) -treatment. These findings suggest that co-medication of rhuEpo in well balanced doses can be used to improve the accumulation of anticancer drugs. Doses and indications may be personalized and refined using theranostic EpoR-probes.

Epoetin beta for the treatment of chemotherapy-induced anemia: an update

Epoetin beta belongs to the class of erythropoiesis-stimulating agents (ESAs) that are currently available to treat anemic patients receiving chemotherapy. Chemotherapy-induced anemia affects a high percentage of cancer patients and, due to its negative effects on disease outcome and the patient’s quality of life, should be treated when first diagnosed. Initial trials with ESAs have shown efficacy in improving quality of life and reducing the need for blood transfusions in patients with chemotherapy-induced anemia. However, recent meta-analyses have provided conflicting data on the impact of ESAs on survival and tumor progression. Here we provide an overview of these recent data and review the role of epoetin beta in the treatment of chemotherapy-induced anemia over the past 20 years.

Erythropoietin and cancer: the unintended consequences of anemia correction

Until 1990, erythropoietin (EPO) was considered to have a single biological purpose and action, the stimulation of red blood cell growth and differentiation. Slowly, scientific and medical opinion evolved, beginning with the discovery of an effect on endothelial cell growth in vitro and the identification of EPO receptors (EPORs) on neuronal cells. We now know that EPO is a pleiotropic growth factor that exhibits an anti-apoptotic action on numerous cells and tissues, including malignant ones. In this article, we present a short discussion of EPO, receptors involved in EPO signal transduction, and their action on non-hematopoietic cells. This is followed by a more detailed presentation of both pre-clinical and clinical data that demonstrate EPO’s action on cancer cells, as well as tumor angiogenesis and lymphangiogenesis. Clinical trials with reported adverse effects of chronic erythropoiesis-stimulating agents (ESAs) treatment as well as clinical studies exploring the prognostic significance of EPO and EPOR expression in cancer patients are reviewed. Finally, we address the use of EPO and other ESAs in cancer patients.

Effect of hypoxia-inducible factor-1α induction by CoCl₂ on breast cancer cells survival: influence of cytochrome-c and survivin

Background: Tumor tissue usually became hypoxic due to disruption of oxygen supply. Adaptation response to hypoxia is mediated by transcription factor, hypoxia- inducible factor-1α (HIF-1α). HIF-1α signaling is known to increase the expression of pro-apoptotic protein cytochrome-c, and anti- apoptotic survivin. In this study we wanted to analyze the role of HIF-1α on breast cancer cells survival through pro-apoptosis cytohrome-c and anti-apoptosis survivin regulation.Methods: Breast cancer cell lines T47D were induced by CoCl2 then harvested to analyze the expression of HIF-1α, protein cytochrome-c, mRNA survivin and cell viabilities.Results: HIF-1α induction by CoCl2 causes the increase of  protein and mRNA of HIF-1α, cytochrome-c protein, and survivin mRNA, but does not cause the changes in cell viability.Conclusion: HIF-1α induction have no effects on breast cancer cell line T47D viabilities due to the balance regulation between pro-apoptosis expression cytochrome-c and anti-apoptosis survivin.

Role of Erythropoietin and Other Growth Factors in Ex Vivo Erythropoiesis

Erythropoiesis is a vital process governed through various factors. There is extreme unavailability of suitable donor due to rare phenotypic blood groups and other related complications like hemoglobinopathies, polytransfusion patients, and polyimmunization. Looking at the worldwide scarcity of blood, especially in low income countries and the battlefield, mimicking erythropoiesis using ex vivo methods can provide an efficient answer to various problems associated with present donor derived blood supply system. Fortunately, there are many ex vivo erythropoiesis methodologies being developed by various research groups using stem cells as the major source material for large scale blood production. Most of these ex vivo protocols use a cocktail of similar growth factors under overlapping growth conditions. Erythropoietin (EPO) is a key regulator in most ex vivo protocols along with other growth factors such as SCF, IL-3, IGF-1, and Flt-3. Now transfusable units of blood can be produced by using these protocols with their set of own limitations. The present paper focuses on the molecular mechanism and significance of various growth factors in these protocols that shall remain helpful for large scale production.

In-vivo detection of the erythropoietin receptor in tumours using positron emission tomography

OBJECTIVE

Recombinant human erythropoietin (rhuEpo) is used clinically to treat anaemia. However, rhuEpo-treated cancer patients show decreased survival rates and erythropoietin receptor (EpoR) expression has been found in patient tumour tissue. Thus, rhuEpo application might promote EpoR(+) tumour progression. We therefore developed the positron emission tomography (PET)-probe (68)Ga-DOTA-rhuEpo and evaluated its performance in EpoR(+) A549 non-small-cell lung cancer (NSCLC) xenografts.

METHODS

(68)Ga-DOTA-rhuEpo was generated by coupling DOTA-hydrazide to carbohydrate side-chains of rhuEpo. Biodistribution was determined in tumour-bearing mice 0.5, 3, 6, and 9 h after probe injection. Competition experiments were performed by co-injecting (68)Ga-DOTA-rhuEpo and rhuEpo in five-fold excess. Probe specificity was further evaluated histologically using Epo-Cy5.5 stainings.

RESULTS

The blood half-life of (68)Ga-DOTA-rhuEpo was 2.6 h and the unbound fraction was cleared by the liver and kidney. After 6 h, the highest tumour to muscle ratio was reached. The highest (68)Ga-DOTA-rhuEpo accumulation was found in liver (10.06 ± 6.26%ID/ml), followed by bone marrow (1.87 ± 0.53%ID/ml), kidney (1.58 ± 0.39%ID/ml), and tumour (0.99 ± 0.16%ID/ml). EpoR presence in these organs was histologically confirmed. Competition experiments showed significantly (p < 0.05) lower PET-signals in tumour and bone marrow at 3 and 6 h.

CONCLUSION

(68)Ga-DOTA-rhuEpo shows favourable pharmacokinetic properties and detects EpoR specifically. Therefore, it might become a valuable radiotracer to monitor EpoR status in tumours and support decision-making in anaemia therapy.

KEY POINTS

• PET-probe (68) Ga-DOTA-rhuEpo was administered to assess the EpoR status in vivo • (68) Ga-DOTA-rhuEpo binds specifically to EpoR positive organs in vivo • Tumour EpoR status determination might enable decision-making in anaemia therapy with rhuEpo.

Erythropoietin promotes breast tumorigenesis through tumor-initiating cell self-renewal

Erythropoietin (EPO) is a hormone that induces red blood cell production. In its recombinant form, EPO is the one of most prescribed drugs to treat anemia, including that arising in cancer patients. In randomized trials, EPO administration to cancer patients has been associated with decreased survival. Here, we investigated the impact of EPO modulation on tumorigenesis. Using genetically engineered mouse models of breast cancer, we found that EPO promoted tumorigenesis by activating JAK/STAT signaling in breast tumor-initiating cells (TICs) and promoted TIC self renewal. We determined that EPO was induced by hypoxia in breast cancer cell lines, but not in human mammary epithelial cells. Additionally, we demonstrated that high levels of endogenous EPO gene expression correlated with shortened relapse-free survival and that pharmacologic JAK2 inhibition was synergistic with chemotherapy for tumor growth inhibition in vivo. These data define an active role for endogenous EPO in breast cancer progression and breast TIC self-renewal and reveal a potential application of EPO pathway inhibition in breast cancer therapy.

Long-term moderate dose exogenous erythropoietin treatment protects from intermittent hypoxia-induced spatial learning deficits and hippocampal oxidative stress in young rats

Exposure to intermittent hypoxia (IH) is associated with cognitive impairments and oxidative stress in brain regions involved in learning and memory. In earlier studies, erythropoietin (EPO) showed a neuroprotective effect in large doses. The aim of the present study was to explore the effect of smaller doses of EPO, such as those used in the treatment of anemia, on IH-induced cognitive deficits and hippocampal oxidative stress in young rats. The effect of concurrent EPO treatment (500 and 1,000 IU/kg/day ip) on spatial learning and memory deficits induced by long-term exposure to IH for 6 weeks was tested using the Morris water maze (MWM) test and the elevated plus maze (EPM) test. Moreover, the effect on hippocampal glutamate and oxidative stress were assessed. Exposure to IH induced a significant impairment of spatial learning and cognition of animals in both MWM and EPM performance parameters. Moreover, hippocampal glutamate and thiobarbituric acid reactive substances (TBARS) increased while antioxidant defenses (GSH and GSH-Px) decreased. EPO in the tested doses significantly reduced the IH-induced spatial learning deficits in both MWM and EPM tests and dose-dependently antagonized the effects of IH on hippocampal glutamate, TBARS, GSH levels, and GSH-Px activity. Treatment with EPO in moderate doses that used for anemia, concurrently with IH exposure can antagonize IH-induced spatial learning deficits and protect hippocampal neurons from IH-induced lipid peroxidation and oxidative stress-induced damage in young rats, possibly through multiple mechanisms involving a potential antioxidative effect.

Erythropoietin is a JAK2 and ERK1/2 effector that can promote renal tumor cell proliferation under hypoxic conditions

Background

Erythropoietin (EPO) provides an alternative to transfusion for increasing red blood cell mass and treating anemia in cancer patients. However, recent studies have reported increased adverse events and/or reduced survival in patients receiving both EPO and chemotherapy, potentially related to EPO-induced cancer progression. Additional preclinical studies that elucidate the possible mechanism underlying EPO cellular growth stimulation are needed.

Methods

Using commercial tissue microarray (TMA) of a variety of cancers and benign tissues, EPO and EPO receptor immunohistochemical staining was performed. Furthermore using a panel of human renal cells (Caki-1, 786-O, 769-P, RPTEC), in vitro and in vivo experiments were performed with the addition of EPO in normoxic and hypoxic states to note phenotypic and genotypic changes.

Results

EPO expression score was significantly elevated in lung cancer and lymphoma (compared to benign tissues), while EPOR expression score was significantly elevated in lymphoma, thyroid, uterine, lung and prostate cancers (compared to benign tissues). EPO and EPOR expression scores in RCC and benign renal tissue were not significantly different. Experimentally, we show that exposure of human renal cells to recombinant EPO (rhEPO) induces cellular proliferation, which we report for the first time, is further enhanced in a hypoxic state. Mechanistic investigations revealed that EPO stimulates the expression of cyclin D1 while inhibiting the expression of p21^cip1 and p27^kip1 through the phosphorylation of JAK2 and ERK1/2, leading to a more rapid progression through the cell cycle. We also demonstrate an increase in the growth of renal cell carcinoma xenograft tumors when systemic rhEPO is administered.

Conclusions

In summary, we elucidated a previously unidentified mechanism by which EPO administration regulates progression through the cell cycle, and show that EPO effects are significantly enhanced under hypoxic conditions.

Erythropoietin is involved in the angiogenic potential of bone marrow macrophages in multiple myeloma

Erythropoietin (Epo) is the crucial cytokine regulator of red blood cell production, and recombinant human erythropoietin (rHuEpo) is widely used in clinical practice for the treatment of anemia, primarily in kidney disease and in cancer. Increasing evidence suggests several biological roles for Epo and its receptor, Epo-R, unrelated to erythropoiesis, including angiogenesis. Epo-R has been found expressed in various non-haematopoietic cells and tissues, and in cancer cells. Here, we detected the expression of Epo-R in bone marrow-derived macrophages (BMMAs) from multiple myeloma (MM) and monoclonal gammopathy of undetermined significance (MGUS) patients and assessed whether Epo/Epo-R axis plays a role in MM macrophage-mediated angiogenesis. We found that Epo-R is over-expressed in BMMAs from MM patients with active disease compared to MGUS patients. The treatment of BMMAs with rHuEpo significantly increased the expression and secretion of key pro-angiogenic mediators, such as vascular endothelial growth factor, hepatocyte growth factor and monocyte chemotactic protein (MCP-1/CCL-2), through activation of JAK2/STAT5 and PI3 K/Akt pathways. In addition, the conditioned media harvested from rHuEpo-treated BMMAs enhanced bone marrow-derived endothelial cell migration and capillary morphogenesis in vitro, and induced angiogenesis in the chorioallantoic membrane of chick embryos in vivo. Furthermore, we found an increase in the circulating levels of several pro-angiogenic cytokines in serum of MM patients with anemia under treatment with Epo. Our findings highlight the direct effect of rHuEpo on macrophage-mediated production of pro-angiogenic factors, suggesting that Epo/Epo-R pathway may be involved in the regulation of angiogenic response occurring in MM.

Epo receptors are not detectable in primary human tumor tissue samples

Erythropoietin (Epo) is a cytokine that binds and activates an Epo receptor (EpoR) expressed on the surface of erythroid progenitor cells to promote erythropoiesis. While early studies suggested EpoR transcripts were expressed exclusively in the erythroid compartment, low-level EpoR transcripts were detected in nonhematopoietic tissues and tumor cell lines using sensitive RT-PCR methods. However due to the widespread use of nonspecific anti-EpoR antibodies there are conflicting data on EpoR protein expression. In tumor cell lines and normal human tissues examined with a specific and sensitive monoclonal antibody to human EpoR (A82), little/no EpoR protein was detected and it was not functional. In contrast, EpoR protein was reportedly detectable in a breast tumor cell line (MCF-7) and breast cancer tissues with an anti-EpoR polyclonal antibody (M-20), and functional responses to rHuEpo were reported with MCF-7 cells. In another study, a functional response was reported with the lung tumor cell line (NCI-H838) at physiological levels of rHuEpo. However, the specificity of M-20 is in question and the absence of appropriate negative controls raise questions about possible false-positive effects. Here we show that with A82, no EpoR protein was detectable in normal human and matching cancer tissues from breast, lung, colon, ovary and skin with little/no EpoR in MCF-7 and most other breast and lung tumor cell lines. We show further that M-20 provides false positive staining with tissues and it binds to a non-EpoR protein that migrates at the same size as EpoR with MCF-7 lysates. EpoR protein was detectable with NCI-H838 cells, but no rHuEpo-induced phosphorylation of AKT, STAT3, pS6RP or STAT5 was observed suggesting the EpoR was not functional. Taken together these results raise questions about the hypothesis that most tumors express high levels of functional EpoR protein.

Human erythropoietin increases the pro-angiogenic potential of A2780 ovarian adenocarcinoma cells under hypoxic conditions

Erythropoietin (Epo) is a key regulator of erythroid cell proliferation, differentiation and apoptosis. In the form of the recombinant protein, it is widely used to treat various types of anemias, including that associated with cancer and with the myelosuppressive effects of chemotherapy, particularly platinum-based regimens. Our previous studies confirmed the presence of Epo receptors (EpoRs) in ovarian adenocarcinoma cell lines and demonstrated that long-term Epo treatment of A2780 cells resulted in the development of a phenotype exhibiting both enhanced Epo signaling and increased paclitaxel resistance. In the present study, we carried out a series of experiments to analyze the pro-angiogenic potential of Epo-treated A2780 and SKOV-3 cells. Our studies revealed that conditioned media of Epo-treated A2780 cells had a stimulative effect on human umbilical vein endothelial cells (HUVECs). This effect was only seen when A2780 cells were incubated under hypoxic conditions. Furthermore, Epo increased the secretion of interleukin (IL)-4, IL-5, IL-6, IL-8, IL-10, IL-12, IL-13, GM-CSF and interferon-γ by A2780 cells that grew in hypoxic conditions. In this regard, conditioned media of hypoxic and Epo-treated A2780 cells induced a significant phosphorylation of STAT-5 in HUVECs. Our results may have important implications for ovarian cancer patients receiving Epo.

Royal jelly prevents the progression of sarcopenia in aged mice in vivo and in vitro

Sarcopenia is characterized by the age-related loss of muscle mass and strength. One of the mechanisms of sarcopenia is the loss in the function and number of muscle satellite cells. Royal jelly (RJ) is a health food used worldwide. To obtain better digestion and absorption than RJ, protease-treated RJ (pRJ) has been developed. RJ and pRJ have been suggested to have potential pharmacological benefits such as prolonging the life span and reducing fatigue. Because these effects may improve sarcopenia and the functions of satellite cells, we examined the effects of RJ or pRJ treatment on the skeletal muscles in an animal model using aged mice. In vivo, RJ/pRJ treatment attenuated the decrease in the muscle weight and grip strength and increased the regenerating capacity of injured muscles and the serum insulin-like growth factor-1 levels compared with controls. In vitro, using isolated satellite cells from aged mice, pRJ treatment increased the cell proliferation rate, promoted cell differentiation, and activated Akt intracellular signaling pathway compared with controls. These findings suggest that RJ/pRJ treatment had a beneficial effect on age-related sarcopenia.

Erythropoietin in cancer: a dilemma in risk therapy

Erythropoietin (EPO) is a frequently prescribed drug for treatment of cancer-related and chemotherapy-induced anemia in cancer patients. Paradoxically, recent preclinical and clinical studies indicate that EPO could potentially accelerate tumor growth and jeopardize survival in cancer patients. In this review I critically discuss the current knowledge and broad biological functions of EPO in association with tumor growth, invasion, and angiogenesis. The emphasis is focused on discussing the complex interplay between EPO and other tumor-derived factors in angiogenesis, tumor growth, invasion, and metastasis. Understanding the multifarious functions of EPO and its reciprocal relation with other signaling pathways is crucial for developing more effective agents for cancer therapy and for minimizing risks for cancer patients.

Plasma vascular endothelial growth factor and angiogenin are positively related to erythropoietin dose in hemodialysis patients

PURPOSE

Experimental data confirmed that erythropoietin (EPO) administration alters the course of various pathological situations such as heart failure and tumor growth by inducing vascular endothelial growth factor-A (VEGF-A) expression. The effect of EPO dose on plasma VEGF-A level in hemodialysis (HD) patients was evaluated. The effect of EPO dose on plasma angiogenin level in HD patients was also evaluated, since angiogenin is necessary for angiogenesis induced by VEGF-A.

METHODS

Thirty two HD patients (10 diabetics) enrolled into the study. Patients were iron replete and did not suffer from infections, autoimmune diseases or malignancies. Plasma VEGF-A and angiogenin, as well as serum interleukin-6 and tumor necrosis factor-α were measured by means of ELISA.

RESULTS

Weekly EPO dose per kg of dry body weight was positively related to both VEGF-A and angiogenin, whereas no relation was detected among VEGF-A or angiogenin and hemoglobin, inflammation or presence of diabetes mellitus. These relations among EPO dose and VEGF-A or angiogenin remained after adjustment for hemoglobin concentration or inflammation or presence of diabetes mellitus.

CONCLUSIONS

EPO dose may affect plasma VEGF-A and angiogenin concentrations in HD patients.

In vivo angiogenic activity of erythropoietin

The role of erythropoietin (Epo) has been demonstrated in tissues outside the hematopoietic system, including the cardiovascular system, where Epo promotes various effects in endothelial cells. Here, we have demonstrated the angiogenic capacity of recombinant human Epo (rhuEpo) in vivo, by means of the chick embryo chorioallantoic membrane (CAM) assay, a well-established in vivo assay to study angiogenesis and antiangiogenesis.

The effect of erythropoietin on normal and neoplastic cells

Erythropoietin (Epo) is an essential hormone that binds and activates the Epo receptor (EpoR) resident on the surface of erythroid progenitor cells, thereby promoting erythropoiesis. Recombinant human erythropoietin has been used successfully for over 20 years to treat anemia in millions of patients. In addition to erythropoiesis, Epo has also been reported to have other effects, such as tissue protection and promotion of tumor cell growth or survival. This became of significant concern in 2003, when some clinical trials in cancer patients reported increased tumor progression and worse survival outcomes in patients treated with erythropoiesis-stimulating agents (ESAs). One of the potential mechanisms proffered to explain the observed safety issues was that functional EpoR was expressed in tumors and/or endothelial cells, and that ESAs directly stimulated tumor growth and/or antagonized tumor ablative therapies. Since then, numerous groups have performed further research evaluating this potential mechanism with conflicting data and conclusions. Here, we review the biology of endogenous Epo and EpoR expression and function in erythropoiesis, and evaluate the evidence pertaining to the expression of EpoR on normal nonhematopoietic and tumor cells.

Erythropoietin receptor contributes to melanoma cell survival in vivo

Erythropoietin (Epo) is widely used clinically to treat anemia associated with various clinical conditions including cancer. Data from several clinical trials suggest significant adverse effect of Epo treatment on cancer patient survival. However, controversy exists whether Epo receptor (EpoR) is functional in cancer cells. In this study, we demonstrated that EpoR mRNA expression was detectable in 90.1% of 65 melanoma cell lines, and increased copy number of the Epo and EpoR loci occurred in 30 and 24.6% of 130 primary melanomas, respectively. EpoR knockdown in melanoma cells resulted in diminished ERK phosphorylation in response to Epo stimulation, decreased cell proliferation and increased response to the inhibitory effect of hypoxia and cisplatin in vitro. EpoR knockdown significantly decreased melanoma xenograft size and tumor invasion in vivo. On the contrary, constitutive activation of EpoR activated cell proliferation pathways in melanoma cells and resulted in increased cell proliferation and resistance to hypoxia and cisplatin treatment in vitro. EpoR activation resulted in significantly larger xenografts with increased tumor invasion of surrounding tissue in vivo. Daily administration of recombinant Epo fails to stimulate melanoma growth in vivo, but the treatment increased vascular size in the xenografts. Increased local recurrence after excision of the primary tumors was observed after Epo treatment. Epo induced angiogenesis in Matrigel plug assays, and neutralization of Epo secreted by melanoma cells results in decreased angiogenesis. These data support that EpoR is functional in melanoma and EpoR activation may promote melanoma progression, and suggest that Epo may stimulate angiogenesis and increase survival of melanoma cells under hypoxic condition in vivo.

Predictive mathematical models of cancer signalling pathways

Complex intracellular signalling networks integrate extracellular signals and convert them into cellular responses. In cancer cells, the tightly regulated and fine-tuned dynamics of information processing in signalling networks is altered, leading to uncontrolled cell proliferation, survival and migration. Systems biology combines mathematical modelling with comprehensive, quantitative, time-resolved data and is most advanced in addressing dynamic properties of intracellular signalling networks. Here, we introduce different modelling approaches and their application to medical systems biology, focusing on the identifiability of parameters in ordinary differential equation models and their importance in network modelling to predict cellular decisions. Two related examples are given, which include processing of ligand-encoded information and dual feedback regulation in erythropoietin (Epo) receptor signalling. Finally, we review the current understanding of how systems biology could foster the development of new treatment strategies in the context of lung cancer and anaemia.

Targeted near-infrared imaging of the erythropoietin receptor in human lung cancer xenografts

The putative presence of the erythropoietin receptor (EpoR) on human cancer cells has given rise to controversial discussion about the use of recombinant human erythropoietin (rhuEpo) for treatment of patients with chemotherapy-induced anemia. In vivo analysis of the EpoR status in tumors could help in elucidating the role of erythropoietin in cancer. Thus, the aim of this study was to develop a targeted EpoR probe for the investigation of EpoR expression in human lung cancer xenografts by fluorescence-mediated tomography.

METHODS

Epo-Cy5.5 was generated by coupling Cy5.5 to rhuEpo. In vitro binding assays were performed using the EpoR-positive non-small cell lung cancer (NSCLC) cell lines A549 (lower EpoR expression) and H838 (higher EpoR expression), the EpoR-negative cell line H2030, and EpoR/EGFP-overexpressing HeLa cells. In vivo specificity of Epo-Cy5.5 was confirmed by competition analyses using micro-CT/fluorescence-mediated tomography fusion imaging. Biodistribution was analyzed over 50 h after injection. Binding of Epo-Cy5.5 was validated on tumor cryosections.

RESULTS

After intravenous injection, the probe was rapidly cleared from the circulation. An accumulation was observed in liver and kidneys, with a maximum at 7 h after injection followed by a decline, indicating renal excretion. Almost constant accumulation of Epo-Cy5.5 was found in bone marrow and tumors, indicating specific receptor binding. The probe allowed the discrimination between H838 with higher EpoR expression (89.54 ± 15.91 nM at 25 h) and A549 tumors with lower EpoR expression (60.45 ± 14.59 nM at 25 h, P < 0.05). Tumor accumulation of Epo-Cy5.5 could be significantly reduced by adding unlabeled rhuEpo (P < 0.05 at 4, 7, and 24 h). In vitro validation confirmed specific binding of Epo-Cy5.5 to the tumor cells, and this binding correlated with the EpoR expression level. Binding was also observed on endothelial cells. Vessel density and Epo-Cy5.5 binding on endothelial cells were comparable.

CONCLUSION

Epo-Cy5.5 allows the longitudinal analysis of EpoR expression in tumors and thereby can investigate the influence of erythropoietin on EpoR expression, tumor growth, and angiogenesis.

Erythropoietin promotes the growth of pituitary adenomas by enhancing angiogenesis

rhEPO is frequently used in clinical practice to treat anemia. However, recently rhEPO has been reported to accelerate tumor growth, progression and metastasis. Many pituitary adenoma patients, particularly those with macroprolactinomas, tend to have anemia and may need rhEPO therapy. To date, whether rhEPO has deleterious effects on pituitary adenomas has not been defined. Here we demonstrated for the first time that human pituitary adenomas are EPOR negative tumors and rhEPO accelerated the tumor growth of MMQ pituitary adenoma xenografts via enhancement of angiogenesis in vivo, whereas rhEPO displayed no direct effect on MMQ cells in vitro. Our mechanistic study showed that rhEPO administration increased phosphorylation of JAK2, STAT3 and VEGF expression in human umbilical vein endothelial cells (HUVECs) in vitro and in MMQ cell xenografts in vivo. Furthermore, VEGF inhibitor attenuated rhEPO induced angiogenesis and delayed tumor growth in MMQ pituitary adenoma xenografts in vivo. JAK2 inhibitor AG490 attenuated EPO induced HUVECs proliferation, phosphorylation of JAK2, STAT3 and VEGF upregulation in vitro and inhibited EPO induced vessel formation in Chicken chorioallantoic membrane (CAM) angiogenesis model in vivo. These results suggest that rhEPO administration may promote the growth of pituitary adenomas by enhancing angiogenesis through EPO-JAK2-STAT3-VEGF signaling pathway. rhEPO should be used with caution in anemia patients bearing pituitary adenoma due to its potential deleterious effects.

Darbepoetin-α promotes neovascularization and cell proliferation in established colorectal liver metastases

BACKGROUND

The erythropoietin-analogue darbepoetin-α (DPO) improves liver function and regeneration after hepatectomy (Phx), however, also enhances Phx-induced tumor cell engraftment and neovascularization. Because it is unknown whether DPO also enhances the growth of established tumors, we herein studied the effect of DPO on established colorectal liver metastases after Phx.

METHODS

CT26.WT cells were implanted into the liver of BALB/c mice. Five days after tumor establishment, animals underwent 50% Phx and received 10 μg/kgBW DPO or saline. Non-Phx animals with DPO or saline-treatment served as controls. Seven days after Phx tumors were analyzed regarding blood vessel formation, leukocyte adhesion, cell proliferation, apoptotic cell death, and growth using intravital fluorescence microscopy, histology, and immunohistochemistry.

RESULTS

The growth of established colorectal liver metastases was slightly stimulated after DPO-treatment in hepatectomized and non-hepatectomized animals. However, tumor vessel formation and tumor cell proliferation were significantly enhanced after DPO-treatment in hepatectomized and non-hepatectomized mice compared with controls. Apoptotic cell death and leukocyte-endothelial cell interaction were significantly reduced after DPO-treatment.

CONCLUSION

Our study indicates that DPO-treatment promotes neovascularization and cell proliferation in established colorectal liver metastases of hepatectomized and non-hepatectomized mice. DPO-application in patients with colorectal liver metastases might promote tumor progression and should therefore be avoided.

The role of erythropoietin and erythropoiesis-stimulating agents in tumor progression

Over the past few decades, understanding of the physiologic function of erythropoietin (EPO) has evolved significantly. EPO binds to erythropoietin receptors (EPOR), initiating signaling that stimulates growth, inhibits apoptosis, and induces the differentiation of erythroid progenitors to increase red blood cell mass. EPO has additionally been shown to exert tissue-protective effects on multiple tissues, suggesting a pleiotropic mechanism of action. Erythropoiesis-stimulating agents (ESA) are used clinically for treating cancer-related anemia [chemotherapy-induced anemia (CIA)]. Recent clinical trials have reported increased adverse events and/or reduced survival in ESA-treated cancer patients receiving chemotherapy, potentially related to EPO-induced cancer progression. Signaling pathways downstream of EPO/EPOR have been shown to influence numerous cellular functions in both normal and tumor cells, including proliferation, apoptosis, and drug resistance. Some studies have reported effects on proliferation, reduced chemotherapy efficacy, reduction of apoptosis, and resistance to selective therapies on cancer cell lines, whereas others have shown null effects. In addition, newer targeted cancer therapies that are directed toward specific signaling pathways may be antagonized by ESAs. This molecular interplay between anticancer agents and potential survival signals triggered by ESAs may have been underestimated and may contribute toward decreased survival seen in certain trials. As more targeted anticancer therapies become available, these types of interactions may mitigate therapeutic efficacy by allowing tumor cells to acquire drug resistance. Therefore, a more complete understanding of the complex pathways involved will allow for the rational use of ESAs for the safe treatment of CIA in oncology patients.

Erythropoietin induces lymph node lymphangiogenesis and lymph node tumor metastasis

Cancer therapy often produces anemia, which is treated with erthropoietin (EPO) to stimulate erythrocyte production. However, concerns have recently arisen that EPO treatment may promote later tumor metastasis and mortality. The mechanisms underlying such effects are unknown, but it is clear that EPO has pleiotropic effects in cell types other than hematopoietic cells. In this study, we investigated how EPO affects lymphangiogenesis and lymph node tumor metastasis in mouse models of breast cancer and melanoma. In these models, EPO increased lymph node lymphangiogenesis and lymph node tumor metastasis in a manner associated with increased migration, capillary-like tube formation, and dose- and time-dependent proliferation of human lymphatic endothelial cells. EPO increased sprouting of these cells in a thoracic duct lymphatic ring assay. These effects were abrogated by cotreatment with specific inhibitors of phosphoinositide 3-kinase or mitogen-activated protein kinase, under conditions in which EPO increased Akt and extracellular signal-regulated kinase 1/2 phosphorylation. Intraperitoneal administration of EPO stimulated peritoneal lymphangiogenesis, and systemic treatment of EPO increased infiltration of CD11b(+) macrophages in tumor-draining lymph nodes. Finally, EPO increased VEGF-C expression in lymph node-derived CD11b(+) macrophages as well as in bone marrow-derived macrophages in a dose- and time-dependent manner. Our results establish that EPO exerts a powerful lymphangiogenic function and can drive both lymph node lymphangiogenesis and nodal metastasis in tumor-bearing animals.

Dinosaurs and ancient civilizations: reflections on the treatment of cancer

Research efforts in the area of palaeopathology have been seen as an avenue to improve our understanding of the pathogenesis of cancer. Answers to questions of whether dinosaurs had cancer, or if cancer plagued ancient civilizations, have captured the imagination as well as the popular media. Evidence for dinosaurian cancer may indicate that cancer may have been with us from the dawn of time. Ancient recorded history suggests that past civilizations attempted to fight cancer with a variety of interventions. When contemplating the issue why a generalized cure for cancer has not been found, it might prove useful to reflect on the relatively limited time that this issue has been an agenda item of governmental attention as well as continued introduction of an every evolving myriad of manmade carcinogens relative to the total time cancer has been present on planet Earth. This article reflects on the history of cancer and the progress made following the initiation of the "era of cancer chemotherapy."

Recombinant human erythropoietin antagonizes trastuzumab treatment of breast cancer cells via Jak2-mediated Src activation and PTEN inactivation

We found that the receptor for erythropoietin (EpoR) is coexpressed with human epidermal growth factor receptor-2 (HER2) in a significant percentage of human breast tumor specimens and breast cancer cell lines. Exposure of HER2 and EpoR dual-positive breast cancer cells to recombinant human erythropoietin (rHuEPO) activated cell signaling. Concurrent treatment of the cells with rHuEPO and trastuzumab reduced the cells' response to trastuzumab both in vitro and in vivo. We identified Jak2-mediated activation of Src and inactivation of PTEN as underlying mechanisms through which rHuEPO antagonizes trastuzumab-induced therapeutic effects. Furthermore, we found that compared with administration of trastuzumab alone, concurrent administration of rHuEPO and trastuzumab correlated with shorter progression-free and overall survival in patients with HER2-positive metastatic breast cancer.

The use of recombinant erythropoietin for the treatment of chemotherapy-induced anemia in patients with ovarian cancer does not affect progression-free or overall survival

BACKGROUND

Studies have suggested that erythropoietin-stimulating agents (ESAs) may affect progression-free survival (PFS) and overall survival (OS) in a variety of cancer types. Because this finding had not been explored previously in ovarian or primary peritoneal carcinoma, the authors of this report analyzed their ovarian cancer population to determine whether ESA treatment for chemotherapy-induced anemia affected PFS or OS.

METHODS

A retrospective review was conducted of women who were treated for ovarian cancer at the corresponding author's institution over a 10-year period (from January 1994 to May 2004). Treatment groups were formed based on the use of an ESA. Two analyses of survival were conducted to determine the effect of ESA therapy on PFS and OS. Disease status was modeled as a function of treatment group using a logistic regression model. Kaplan-Meier curves were generated to compare the groups, and a Cox proportional hazards model was fit to the data.

RESULTS

In total, 343 women were identified. The median age was 57 (interquartile range, 48-68 years). The majority of women were Caucasian (n = 255; 74%) and were diagnosed with stage III (n = 210; 61%), epithelial (n = 268; 78%) ovarian cancer. Although the disease stage at diagnosis and surgical staging significantly affected the rates of disease recurrence and OS, the receipt of an ESA had no effect on PFS (P = .9) or OS (P = .25).

CONCLUSIONS

The current results indicated that there was no difference in cancer-related PFS or OS with use of ESA in this cohort of women treated for ovarian cancer.

Erythropoietin 2nd cerebral protection after acute injuries: a double-edged sword?

Over the past 15 years, a large body of evidence has revealed that the cytokine erythropoietin exhibits non-erythropoietic functions, especially tissue-protective effects. The discovery of EPO and its receptors in the central nervous system and the evidence that EPO is made locally in response to injury as a protective factor in the brain have raised the possibility that recombinant human EPO (rhEPO) could be administered as a cytoprotective agent after acute brain injuries. This review highlights the potential applications of rhEPO as a neuroprotectant in experimental and clinical settings such as ischemia, traumatic brain injury, and subarachnoid and intracerebral hemorrhage. In preclinical studies, EPO prevented apoptosis, inflammation, and oxidative stress induced by injury and exhibited strong neuroprotective and neurorestorative properties. EPO stimulates vascular repair by facilitating endothelial progenitor cell migration into the brain and neovascularisation, and it promotes neurogenesis. In humans, small clinical trials have shown promising results but large prospective randomized studies failed to demonstrate a benefit of EPO for brain protection and showed unwanted side effects, especially thrombotic complications. Recently, regions have been identified within the EPO molecule that mediate tissue protection, allowing the development of non-erythropoietic EPO variants for neuroprotection conceptually devoid of side effects. The efficacy and the safety profile of these new compounds are still to be demonstrated to obtain, in patients, the benefits observed in experimental studies.

Epo is involved in angiogenesis in human glioma

In this study, the extent of angiogenesis, evaluated as microvascular density, and the immunoreactivity of tumor cells to erythropoietin (Epo) and of endothelial cells to Epo receptor (EpoR) have been correlated in human glioma specimens, and the effect of anti-Epo antibody on glioma-induced angiogenesis in vivo in the chick embryo chorioallantoic membrane (CAM) has been investigated. Results show that: (1) Epo/EpoR expression correlates with angiogenesis, (2) in the CAM assay, tumor bioptic specimens induce a strong angiogenic response, comparable to that induced by VEGF, and (3) an anti-Epo antibody co-administered with tumor bioptic specimens significantly inhibits the angiogenic response. These findings suggest the presence of a loop in the Epo/EpoR system, i.e. Epo is secreted by glioma tumor cells and it affects glioma vascular endothelial cells via its receptor and promotes angiogenesis in a paracrine manner. Moreover, as demonstrated by in vivo experiments, Epo is responsible for the strong angiogenic response induced by human glioma bioptic specimens, because an anti-Epo antibody is able to significantly inhibit this response.