Erythropoietin Signaling in the Microenvironment of Tumors and Healthy Tissues

A new role for erythropoietin in the homeostasis of red blood cells

The regulation of red blood cell (RBC) homeostasis is widely assumed to rely on the control of cell production by erythropoietin (EPO) and the destruction of cells at a fixed, species-specific age. In this work, we show that such a regulatory mechanism would be a poor homeostatic solution to satisfy the changing needs of the body. Effective homeostatic control would require RBC lifespan to be variable and tightly regulated. We suggest that EPO may control RBC lifespan by determining CD47 expression in newly formed RBCs and SIRP-α expression in sinusoidal macrophages. EPO could also regulate the initiation and intensity of anti-RBC autoimmune responses that curtail RBC lifespan in some circumstances. These mechanisms would continuously modulate the rate of RBC destruction depending on oxygen availability. The control of RBC lifespan by EPO and autoimmunity emerges as a key mechanism in the homeostasis of RBCs.

Novel Combination of Erythropoietin and Romiplostim to Treat Chemotherapy-Induced Anemia and Thrombocytopenia via Pharmacodynamic Interaction on Hematopoietic Stem and Progenitor Cells

Chemotherapy-induced anemia and thrombocytopenia (CIAT) in cancer patients are often caused by the damage of hematopoietic stem and progenitor cells (HSPCs) in the bone marrow. We have previously shown that romiplostim, a thrombopoietin receptor agonist that could stimulate the expansion of HSPCs, could synergize with recombinant human erythropoietin (rHuEPO) to promote erythropoiesis in addition to stimulating platelet production, whereas rHuEPO could influence the platelet count through stem cell competition. Therefore, we hypothesize that a combination of romiplostim with rHuEPO can alleviate CIAT simultaneously, while minimizing the risk of thrombosis. In this study, we demonstrated that rHuEPO and romiplostim exhibit no stimulatory effects on the growth and invasion of LA-7 cancer cells both in vitro and in vivo. Using a rat model with carboplatin-induced anemia and thrombocytopenia, we showed that the red blood cells and hemoglobin concentration recovered faster, and the secondary thrombocytopenia was alleviated in the rHuEPO and romiplostim combination therapy groups compared with the corresponding rHuEPO monotherapy groups. The rebound phenomenon of platelets was inhibited compared with the romiplostim monotherapy group. In vitro study further demonstrated that romiplostim expands HSPCs and synergizes with rHuEPO to promote erythropoiesis, while rHuEPO inhibited megakaryopoiesis. Furthermore, we developed a mechanism-based pharmacokinetic-pharmacodynamic model to quantify the effects of the two drugs. This study suggests that rHuEPO and romiplostim combination therapy can treat CIAT simultaneously in rats while minimizing the risk of thrombosis, indicating that combination therapy might be superior to monotherapy in the supportive therapy of cancer patients undergoing chemotherapy.

Effect of recombinant human erythropoietin combined with iron sucrose on postoperative hemoglobin in patients undergoing artificial joint replacement

With the aging of the population, an increasing number of elderly patients are opting for artificial joint replacement, leading to the exploration of various rapid rehabilitation programs in the perioperative period. In this study, we aimed to investigate the effectiveness of combining recombinant human erythropoietin and iron sucrose in altering the range and trend of postoperative hemoglobin in patients undergoing arthroplasty. Specifically, we will examine whether this combination can effectively alter the rise and fall of postoperative haemoglobin, identify the inflection point of haemoglobin change or recovery after arthroplasty, and assess the effect of treatment on serum iron in postoperative blood. We conducted a retrospective study of 138 patients who underwent unilateral total joint arthroplasty by the same surgeon in the same hospital before July 2022. The results of this study may provide valuable insights for the development of effective rehabilitation programs for patients undergoing arthroplasty.

FLI1 accelerates leukemogenesis through transcriptional regulation of pyruvate kinase-L/R and other glycolytic genes

In cancer cells, multiple oncogenes and tumor suppressors control glycolysis to sustain rapid proliferation. The ETS-related transcription factor Fli1 plays a critical role in the induction and progression of leukemia, yet, the underlying mechanism of this oncogenic event is still not fully understood. In this study, RNAseq analysis of FLI1-depleted human leukemic cells revealed transcriptional suppression of the PKLR gene and activation of multiple glycolytic genes, such as PKM1/2. Pharmacological inhibition of glycolysis by PKM2 inhibitor, Shikonin, significantly suppressed leukemic cell proliferation. FLI1 directly binds to the PKLR promoter, leading to the suppression of this inhibitor of glycolysis. In accordance, shRNA-mediated depletion of PKLR in leukemic HEL cells expressing high levels of FLI1 accelerated leukemia proliferation, pointing for the first time to its tumor suppressor function. PKLR knockdown also led to downregulation of the erythroid markers EPOR, HBA1, and HBA2 and suppression of erythroid differentiation. Interestingly, silencing of PKLR in HEL cells significantly increased FLI1 expression, which was associated with faster proliferation in culture. In FLI1-expressing leukemic cells, lower PKLR expression was associated with higher expression of PKM1 and PKM2, which promote aerobic glycolysis. Finally, injection of pyruvate, a known inhibitor of glycolysis, into leukemia mice significantly suppressed leukemogenesis. These results demonstrate that FLI1 promotes leukemia in part by inducing glycolysis, implicates PKLR in erythroid differentiation, and suggests that targeting glycolysis may be an attractive therapeutic strategy for cancers driven by FLI1 overexpression.

A novel cuproptosis-related prognostic signature and potential value in HCC immunotherapy

Background: Copper metabolism plays an important role in the tumor microenvironment, and cuproptosis is the last discovered programmed cell death process. However, the potential mechanism of cuproptosis in regulating the immune microenvironment of HCC remains unclear.

Methods: A total of 716 HCC patients with complete mRNA expression and survival information were collected from three public HCC cohorts (TCGA-LIHC cohort, n = 370; GSE76427 cohort, n = 115; ICGC-LIRI cohort, n = 231). The unsupervised clustering analysis (NMF) was performed to identify three different cuproptosis-related subtypes. The univariate-Cox, lasso-Cox and multivariate-Cox regression analyses were performed to screen the cuproptosis related and construct the cuproptosis-related prognosis signature (Cu-PS). The immune cell infiltration was estimated by both CIBERSORT and MCPcounter algorithms.

Results: This study identified three distinct cuproptosis-related metabolic patterns, which presented different pathway enrichment and immune cell infiltration. The Cu-PS, a 5-genes (C7, MAGEA6, HK2, CYP26B1 and EPO) signature, was significantly associated with TNM stage, tumor mutational burden (TMB), drugs sensitivity, and immunotherapies response.

Conclusion: This study performed a multi-genetic analysis of cuproptosis-related genes and further explored the regulatory mechanism of cuproptosis in HCC. The Cu-PS might be a useful biomarker for predicting immunotherapy response and enhancing the diagnosis and treatment of HCC.

Cognitive Impairment and Dementia: Gaining Insight through Circadian Clock Gene Pathways

Neurodegenerative disorders affect fifteen percent of the world's population and pose a significant financial burden to all nations. Cognitive impairment is the seventh leading cause of death throughout the globe. Given the enormous challenges to treat cognitive disorders, such as Alzheimer's disease, and the inability to markedly limit disease progression, circadian clock gene pathways offer an exciting strategy to address cognitive loss. Alterations in circadian clock genes can result in age-related motor deficits, affect treatment regimens with neurodegenerative disorders, and lead to the onset and progression of dementia. Interestingly, circadian pathways hold an intricate relationship with autophagy, the mechanistic target of rapamycin (mTOR), the silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae) (SIRT1), mammalian forkhead transcription factors (FoxOs), and the trophic factor erythropoietin. Autophagy induction is necessary to maintain circadian rhythm homeostasis and limit cortical neurodegenerative disease, but requires a fine balance in biological activity to foster proper circadian clock gene regulation that is intimately dependent upon mTOR, SIRT1, FoxOs, and growth factor expression. Circadian rhythm mechanisms offer innovative prospects for the development of new avenues to comprehend the underlying mechanisms of cognitive loss and forge ahead with new therapeutics for dementia that can offer effective clinical treatments.

Targeting the core of neurodegeneration: FoxO, mTOR, and SIRT1

The global increase in lifespan noted not only in developed nations, but also in large developing countries parallels an observed increase in a significant number of non-communicable diseases, most notable neurodegenerative disorders. Neurodegenerative disorders present a number of challenges for treatment options that do not resolve disease progression. Furthermore, it is believed by the year 2030, the services required to treat cognitive disorders in the United States alone will exceed $2 trillion annually. Mammalian forkhead transcription factors, silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae), the mechanistic target of rapamycin, and the pathways of autophagy and apoptosis offer exciting avenues to address these challenges by focusing upon core cellular mechanisms that may significantly impact nervous system disease. These pathways are intimately linked such as through cell signaling pathways involving protein kinase B and can foster, sometimes in conjunction with trophic factors, enhanced neuronal survival, reduction in toxic intracellular accumulations, and mitochondrial stability. Feedback mechanisms among these pathways also exist that can oversee reparative processes in the nervous system. However, mammalian forkhead transcription factors, silent mating type information regulation 2 homolog 1, mechanistic target of rapamycin, and autophagy can lead to cellular demise under some scenarios that may be dependent upon the precise cellular environment, warranting future studies to effectively translate these core pathways into successful clinical treatment strategies for neurodegenerative disorders.