Recombinant human erythropoietin alpha modulates the effects of radiotherapy on colorectal cancer microvessels

Recombinant human erythropoietin accelerated the proliferation of non-small cell lung cancer cell lines and reduced the expression of VEGF, HIF-1α, and PD-L1 under a simulated hypoxic environment in vitro

Background

As erythropoietin (EPO) has been used to treat anemia in cancer patients, negative controversy has continued. Unfortunately, its effects on non-small-cell lung carcinoma (NSCLC) cell lines are uncertain and the phenomenon of inducing immune escape of tumor cells remains to be explored. This study aimed to provide an important basis for the application of exogenous EPO in the treatment of tumor-associated anemia.

Methods

Cells were cultured in 1% O2, 5% CO2, and 94% N2 to simulate a hypoxic environment of the tumor. A549 cell line (lower expression EPOR) and NCI-H838 cell line (higher expression EPOR) were treated with 2 and 8 U/ml recombinant human EPO (rhEPO). CCK-8 method was used to determine the logarithmic growth phase of the cells and to detect cell proliferation. The expression levels of VEGF, HIF-1α, and PD-L1 were determined by western blot. One-way ANOVA was used for statistical analysis between groups, with p < 0.05 indicating a significant difference.

Results

Hypoxia itself could decrease the survival rate of NSCLC cells. Under the hypoxic condition, rhEPO induced tumor cells proliferation, especially in the NCI-H838 cell line, where 2 U/ml rhEPO increased the total number of surviving cells (Hypoxia + rhEPO 2 U/ml vs. Hypoxia, p < 0.05). Western blot analysis showed that hypoxia upregulated the expression of VEGF, HIF-1α, and PD-L1 in NSCLC cell lines (Normoxia vs. Hypoxia, p < 0.05), but may not be dependent on the expression levels of EPOR. RhEPO decreased the expression levels of VEGF and HIF-1α. In the A549 cell line, it depended on the concentration of rhEPO and was particularly obvious in HIF-1α (Hypoxia vs. Hypoxia + rhEPO 2 U/ml vs. Hypoxia + rhEPO 8 U/ml, p < 0.05). A low concentration of rhEPO may not reduce VEGF expression. In the NCI-H838 cell line, the effect of rhEPO on VEGF was more obvious, but it may be independent of rhEPO concentrations. The downregulation of PD-L1 expression by rhEPO was only presented in the A549 cell line and required higher rhEPO concentrations (Hypoxia + rhEPO 8 U/ml vs. Hypoxia&Hypoxia + rhEPO 2 U/ml, p < 0.05).

Conclusion

The effect of prolonged high concentrations of rhEPO under hypoxic conditions resulted in accelerated cells proliferation of non-small-cell lung cancer and was independent of EPOR expression levels on the cell lines surface. Hypoxia resulted in increased expression of VEGF, HIF-1α, and PD-L1 on the NSCLC cell lines. Under normoxic conditions, rhEPO did not affect the expression of VEGF, HIF-1α, and PD-L1; but under hypoxic conditions, the application of rhEPO reduced the expression of VEGF, HIF-1α, and PD-L1, producing an impact on the biological behavior of tumor cells.

Molecular imaging of tumor-associated angiogenesis using a novel magnetic resonance imaging contrast agent targeting αvβ 3 integrin

BACKGROUND

The recent introduction of biological anticancer therapy has renewed the interest in functional imaging of tumor-associated angiogenesis (TAA) as a tool to monitor early therapy response. The present study evaluated imaging of TAA using P1227, a novel, small molecular magnetic resonance imaging (MRI) probe targeting αvβ3 integrin.

METHODS

HT29 human colorectal cancers were grown in athymic mice. Dynamic MRI was performed using a three-dimensional VIBE sequence up to 110 min after injection of P1227 or gadolinium-tetraazacyclododecane tetraacetic acid (Gd-DOTA). Specificity was assessed by using P1227 1 h after intravenous administration of the αvβ3 inhibitor cilengitide. Regions of interest were drawn encompassing the tumor rim and normal muscle. Imaging data were compared with microvessel density and αvβ3 expression.

RESULTS

Using P1227, specific enhancement of the angiogenic tumor rim, but not of normal muscle, was observed, whereas Gd-DOTA enhanced tumor and normal muscle. After administering cilengitide, enhancement with P1227, but not with DOTA, was significantly suppressed during the first 20 min. When using P1227, a significant correlation was observed between normalized enhancement of the tumor rim and immunohistochemical αvβ3 integrin expression.

CONCLUSIONS

Molecular MRI using a small monogadolinated tracer targeting αvβ3 integrin and moderate magnetic field strength holds promise in assessing colorectal TAA.

Assessment of neovascular permeability in a pancreatic tumor model using dynamic contrast-enhanced (DCE) MRI with contrast agents of different molecular weights

OBJECT

We evaluated the relationship of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI)-derived pharmacokinetic parameters and contrast agents with different molecular weights (MW) in a pancreatic tumor mouse model.

MATERIALS AND METHODS

Panc02 tumors were induced in mice at the hind leg. DCE-MRI was performed using Gadolinium (Gd)-based contrast agents with different MW: Gd-DOTA (0.5 kDa), P846 (3.5 kDa), and P792 (6.47 kDa). Quantitative vascular parameters (AUC, K(trans), V(e), and V(p)) were calculated according to a modified Tofts two-compartment model. Values for all contrast groups were compared for tumor and control (muscle) tissues.

RESULTS

Values for K(trans) and V(e) were significantly higher in tumor tissue than in muscle tissue. When comparing contrast agents, lowest absolute K(trans) values were observed using P792. The relative increase in K(trans) in tumor tissue compared with normal tissue was highest after the use of P792. In both tumor and normal tissues, K(trans) decreased with increasing molecular weight of the contrast agent used.

CONCLUSION

It was demonstrated that values for the different DCE-MRI vascular (permeability) parameters are highly dependent on the contrast agent used. Due to their potential to better differentiate tumor from muscle tissue, higher molecular weight contrast agents show promise when evaluating tumors using DCE-MRI.

Novel avenues of drug discovery and biomarkers for diabetes mellitus

Globally, developed nations spend a significant amount of their resources on health care initiatives that poorly translate into increased population life expectancy. As an example, the United States devotes 16% of its gross domestic product to health care, the highest level in the world, but falls behind other nations that enjoy greater individual life expectancy. These observations point to the need for pioneering avenues of drug discovery to increase life span with controlled costs. In particular, innovative drug development for metabolic disorders such as diabetes mellitus becomes increasingly critical given that the number of diabetic people will increase exponentially over the next 20 years. This article discusses the elucidation and targeting of novel cellular pathways that are intimately tied to oxidative stress in diabetes mellitus for new treatment strategies. Pathways that involve wingless, β-nicotinamide adenine dinucleotide (NAD(+)) precursors, and cytokines govern complex biological pathways that determine both cell survival and longevity during diabetes mellitus and its complications. Furthermore, the role of these entities as biomarkers for disease can further enhance their utility irrespective of their treatment potential. Greater understanding of the intricacies of these unique cellular mechanisms will shape future drug discovery for diabetes mellitus to provide focused clinical care with limited or absent long-term complications.

Oxidative stress: Biomarkers and novel therapeutic pathways

Oxidative stress significantly impacts multiple cellular pathways that can lead to the initiation and progression of varied disorders throughout the body. It therefore becomes imperative to elucidate the components and function of novel therapeutic strategies against oxidative stress to further clinical diagnosis and care. In particular, both the growth factor and cytokine erythropoietin (EPO) and members of the mammalian forkhead transcription factors of the O class (FoxOs) may offer the greatest promise for new treatment regimens since these agents and the cellular pathways they oversee cover a range of critical functions that directly influence progenitor cell development, cell survival and degeneration, metabolism, immune function, and cancer cell invasion. Furthermore, both EPO and FoxOs function not only as therapeutic targets, but also as biomarkers of disease onset and progression, since their cellular pathways are closely linked and overlap with several unique signal transduction pathways. However, biological outcome with EPO and FoxOs may sometimes be both unexpected and undesirable that can raise caution for these agents and warrant further investigations. Here we present the exciting as well as complicated role EPO and FoxOs possess to uncover the benefits as well as the risks of these agents for cell biology and clinical care in processes that range from stem cell development to uncontrolled cellular proliferation.

Combined effect of EPO and radiotherapy on the expression of endogenous molecular markers of tumor metabolism and metastasis

Erythropoietin (EPO) has been used to correct cancer-related anemia and to improve tumor hypoxia, which both adversely affect the clinical condition of cancer patients and response to radiotherapy. Data available on the effects of EPO treatment in cancer are, however, conflicting. Several clinical studies investigating the influence of EPO treatment have given contradictory results as to whether or not this treatment positively influences survival. In light of these conflicting results, we studied the effects of EPO treatment either alone or in combination with radiotherapy on tumor oxygenation and on the expression pattern of several proteins related to tumor metabolism, survival, and spread in a rat colorectal cancer model. We found a statistically significant upregulation of hexokinase I, N-cadherin, and glucose transporter 3 when EPO treatment was combined with radiotherapy. Because these three proteins have distinct functions in protecting the cell in compromised conditions, these results indicate a detrimental role for the combination of EPO treatment and radiotherapy through the stimulation of tumor-cell metabolism, inhibition of apoptosis, and stimulation of tumor spread and seem to indicate that recombinant human EPO treatment negatively modulates radiotherapy efficacy.

Erythropoietin, forkhead proteins, and oxidative injury: biomarkers and biology

Oxidative stress significantly impacts multiple cellular pathways that can lead to the initiation and progression of varied disorders throughout the body. It therefore becomes imperative to elucidate the components and function of novel therapeutic strategies against oxidative stress to further clinical diagnosis and care. In particular, both the growth factor and cytokine erythropoietin (EPO), and members of the mammalian forkhead transcription factors of the O class (FoxOs), may offer the greatest promise for new treatment regimens, since these agents and the cellular pathways they oversee cover a range of critical functions that directly influence progenitor cell development, cell survival and degeneration, metabolism, immune function, and cancer cell invasion. Furthermore, both EPO and FoxOs function not only as therapeutic targets, but also as biomarkers of disease onset and progression, since their cellular pathways are closely linked and overlap with several unique signal transduction pathways. Yet, EPO and FoxOs may sometimes have unexpected and undesirable effects that can raise caution for these agents and warrant further investigations. Here we present the exciting as well as the complex role that EPO and FoxOs possess to uncover the benefits as well as the risks of these agents for cell biology and clinical care in processes that range from stem cell development to uncontrolled cellular proliferation.

Erythropoietin: elucidating new cellular targets that broaden therapeutic strategies

Given that erythropoietin (EPO) is no longer believed to have exclusive biological activity in the hematopoietic system, EPO is now considered to have applicability in a variety of nervous system disorders that can overlap with vascular disease, metabolic impairments, and immune system function. As a result, EPO may offer efficacy for a broad number of disorders that involve Alzheimer's disease, cardiac insufficiency, stroke, trauma, and diabetic complications. During a number of clinical conditions, EPO is robust and can prevent metabolic compromise, neuronal and vascular degeneration, and inflammatory cell activation. Yet, use of EPO is not without its considerations especially in light of frequent concerns that may compromise clinical care. Recent work has elucidated a number of novel cellular pathways governed by EPO that can open new avenues to avert deleterious effects of this agent and offer previously unrecognized perspectives for therapeutic strategies. Obtaining greater insight into the role of EPO in the nervous system and elucidating its unique cellular pathways may provide greater cellular viability not only in the nervous system but also throughout the body.

Erythropoietin and oxidative stress

Unmitigated oxidative stress can lead to diminished cellular longevity, accelerated aging, and accumulated toxic effects for an organism. Current investigations further suggest the significant disadvantages that can occur with cellular oxidative stress that can lead to clinical disability in a number of disorders, such as myocardial infarction, dementia, stroke, and diabetes. New therapeutic strategies are therefore sought that can be directed toward ameliorating the toxic effects of oxidative stress. Here we discuss the exciting potential of the growth factor and cytokine erythropoietin for the treatment of diseases such as cardiac ischemia, vascular injury, neurodegeneration, and diabetes through the modulation of cellular oxidative stress. Erythropoietin controls a variety of signal transduction pathways during oxidative stress that can involve Janus-tyrosine kinase 2, protein kinase B, signal transducer and activator of transcription pathways, Wnt proteins, mammalian forkhead transcription factors, caspases, and nuclear factor kappaB. Yet, the biological effects of erythropoietin may not always be beneficial and may be poor tolerated in a number of clinical scenarios, necessitating further basic and clinical investigations that emphasize the elucidation of the signal transduction pathways controlled by erythropoietin to direct both successful and safe clinical care.

Triple play: promoting neurovascular longevity with nicotinamide, WNT, and erythropoietin in diabetes mellitus

Oxidative stress is a principal pathway for the dysfunction and ultimate destruction of cells in the neuronal and vascular systems for several disease entities, not promoting the ravages of oxidative stress to any less of a degree than diabetes mellitus. Diabetes mellitus is increasing in incidence as a result of changes in human behavior that relate to diet and daily exercise and is predicted to affect almost 400 million individuals worldwide in another two decades. Furthermore, both type 1 and type 2 diabetes mellitus can lead to significant disability in the nervous and cardiovascular systems, such as cognitive loss and cardiac insufficiency. As a result, innovative strategies that directly target oxidative stress to preserve neuronal and vascular longevity could offer viable therapeutic options to diabetic patients in addition to more conventional treatments that are designed to control serum glucose levels. Here we discuss the novel application of nicotinamide, Wnt signaling, and erythropoietin that modulate cellular oxidative stress and offer significant promise for the prevention of diabetic complications in the nervous and vascular systems. Essential to this process is the precise focus upon diverse as well as common cellular pathways governed by nicotinamide, Wnt signaling, and erythropoietin to outline not only the potential benefits, but also the challenges and possible detriments of these therapies. In this way, new avenues of investigation can hopefully bypass toxic complications, or at the very least, avoid contraindications that may limit care and offer both safe and robust clinical treatment for patients.

Raves and risks for erythropoietin

Global use of erythropoietin (EPO) continues to increase as a proven agent for the treatment of anemia. Yet, EPO is no longer believed to have exclusive biological activity in the hematopoietic system and is now considered applicable for a variety of disorders such as diabetes, Alzheimer's disease, and cardiovascular disease. Treatment with EPO is considered to be robust and can prevent metabolic compromise, neuronal and vascular degeneration, and inflammatory cell activation. On the converse side, observations that EPO administration is not without risk have fueled controversy. Here we present recent advances that have elucidated a number of novel cellular pathways governed by EPO to open new therapeutic avenues for this agent and avert its potential deleterious effects.