Upregulation Of Hypoxia-inducible Factor Research Articles

Maternal infection with SARS-CoV-2 during early pregnancy induces hypoxia at the maternal-fetal interface.

The coronavirus disease 2019 (COVID-19) pandemic increases the risk of adverse fetal outcomes during pregnancy. Maternal infection during pregnancy, particularly with cytomegalovirus (CMV), hepatitis B and C virus, and human immunodeficiency virus can have detrimental effects on both mother and fetus, potentially leading to adverse outcomes such as spontaneous abortion or neonatal infection. However, the impact of severe acute respiratory syndrome coronavirus (SARS-CoV-2) infection on the maternal-fetal interface remains poorly understood. In this study, we initially utilised immunofluorescence and immunohistochemical to investigate placental samples from pregnant women who were infected with SARS-CoV-2 during the first trimester. Our data indicate that infection in the first trimester induces an upregulation of hypoxia inducible factor (HIF) levels at the maternal-fetal interface. Subsequently, single-cell RNA sequencing and metabolomics sequencing analyses reveal alterations in maternal-fetal interface. Remarkably, immune cells exhibited low expression levels of HIF possibly associated with immune activation. Furthermore, our findings demonstrate a gradual reduction in transcriptome and metabolic changes as gestation progressed beyond 12-16 weeks compared to samples obtained at 6-8 weeks gestation. Overall, our study suggests that early-stage SARS-CoV-2 infection during the first trimester leads to severe hypoxia and aberrant cell metabolism at the maternal-fetal interface which gradually resolves as pregnancy progresses. Nevertheless, these abnormal changes may have long-term implications for maternal-fetal interface development.

The effect of PHD inhibitor on tumor microenvironment and tumor immune response

Since the approval of HIF-PH inhibitors, HIF-PH inhibitors have been used clinically, and many studies and clinical case reports have been reported in Japan. A lot of information has been accumulated on clinical usage. However, HIF-PH inhibitors require careful administration for cancer patients due to their action mechanism through upregulating hypoxia-inducible factors (HIFs) level. In cancer cells, HIFs affect tumor progression and contribute to chemo- and radio-resistance. On the other hand, upregulation of HIFs in immune cells is associated with inflammation and suppress tumor progression. However, these controversial effects are not clear in in vivo model. It is needed to reveal whether upregulating HIFs level is beneficial for cancer therapy or not. We have previously reported that HIF-PH inhibitor treatment in tumor bearing mice model led to reconstitute tumor blood vessel and inhibit tumor growth. In addition, these phenomena were caused by tumor infiltrated macrophages and they altered these phenotypes. In this review, we will describe our findings on the mechanism of tumor growth suppression by HIF-PH inhibitors. We also want to mention the risks and benefits of future HIF-PH inhibitors.

Abstract 4296: Investigating metabolic sensitivity and organization of renal cell carcinoma: To enhance effective therapies and patient survival

Abstract Background: Renal cell carcinoma (RCC) is the 6th most common cancer in men and the 9th most common in women in the United States. RCC tissues are metabolically dysfunctional, often resulting from loss of von-Hippel Lindau (VHL) and consequent upregulation of hypoxia-inducible factor (HIF1/2). HIF1a is a transcription factor that upregulates glycolytic gene expression. Current therapies, including immune checkpoint inhibitors and tyrosine kinase inhibitors, have shown improvements in the outcomes of RCC patients, however, there are no biomarkers clinically available to predict the efficacy of these drugs. While genomic data and transcriptomic signatures have been investigated, they are not used in clinical practice due to lack of prospective validation. Understanding additional pathways pertaining to metabolic features of RCC, is critical. Our bulk gene expression analysis of primary RCC samples from TCGA-KIRC show a predominance of genes expressing mitochondrial ribosomal proteins and electron transport chain in tumors that relapsed early after nephrectomy, warranting further validation. Aim: We aim to investigate changes in metabolic adaptation in RCC cells from kidney cancer cell lines (VHL mutant) and primary cells from human-matched primary and metastatic kidney cancer sites. Using a novel biosensor-based technique developed in the Albeck lab, we aim to identify the dependence of live RCC cells on specific metabolic pathways and test the effect of standard-of-care (SOC) pathway inhibitors such as tyrosine kinase, HIF pathway, metabolic pathway inhibitors impacting tumorigenicity. Methods: To examine functional metabolic behavior in single cells, we generated immortalized cell lines (MCF10A, 184A1, FL83B and HBE-1) stably transfected with biosensors for the activity of AKT, glycolysis, mTOR and AMPK pathway. Data from Live-cells treated with metabolic inhibitors were collected and analyzed using our MATLAB-based pipeline. We have extended the analysis to RCC cell lines (786-O cell lines) and primary cells collected from nephrectomy specimens and matched metastatic biopsy samples, using current SOC pathway inhibitors (including sorafenib, sunitinib, belzutifan) and investigational metabolic drugs (metformin, IACS-010759, niclosamide). Results & Conclusion: Our preliminary results show an association of high OX-PHOS with primary tumors from early relapse after nephrectomy than the relapsed late tumors. Our biosensor single cell data show that even genetically homogeneous cell populations can vary in their usage of OXPHOS and glycolysis to supply ATP for cell growth. Tumor gene expression profile coupled with biosensor data, will address mechanism behind this metabolic shift in RCC tumors in primary cells isolated from primary and metastatic sites. Our research will improve tumor prognosis and allow designing therapeutic trials. Citation Format: Madhura Patankar, John Albeck, Shuchi Gulati. Investigating metabolic sensitivity and organization of renal cell carcinoma: To enhance effective therapies and patient survival [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4296.

Synergistic effect of ROS-generating polydopamine on drug-induced bone tissue regeneration.

A PHD (prolyl hydroxylase) inhibitor, 1,4-dihydrophenonthrolin-4-one-3-carboxylic acid (1,4-DPCA), is a drug that can artificially promote tissue regeneration by enhancing metabolic activity through the upregulation of hypoxia inducible factor 1 subunit alpha (Hif-1α) under normoxic conditions. This study presents a novel design methodology for a drug delivery system to maximize the regenerative effect of 1,4-DPCA. Specifically, by encapsulating 1,4-DPCA in polydopamine (PDA) that generates reactive oxygen species (ROS), the combined effects of Hif-1α upregulation and the induction of cellular antioxidant defense mechanisms by localized ROS can significantly enhance tissue regeneration. The study confirmed that each material (PDA and 1,4-DPCA) triggers a positive synergistic effect on the regenerative mechanisms. As a result, the use of a PDA drug delivery system loaded with 1,4-DPCA showed approximately six times greater bone regeneration compared to the control (no treatment) in a mouse calvarial defect model.

Hypoxia-inducible factor upregulation by roxadustat attenuates drug reward by altering brain iron homoeostasis

Substance use disorder remains a major challenge, with an enduring need to identify and evaluate new, translational targets for effective treatment. Here, we report the upregulation of Hypoxia-inducible factor-1α (HIF-1α) expression by roxadustat (Rox), a drug developed for renal anemia that inhibits HIF prolyl hydroxylase to prevent degradation of HIF-1α, administered either systemically or locally into selected brain regions, suppressed morphine (Mor)-induced conditioned place preference (CPP). A similar effect was observed with methamphetamine (METH). Moreover, Rox also inhibited the expression of both established and reinstated Mor-CPP and promoted the extinction of Mor-CPP. Additionally, the elevation of HIF-1α enhanced hepcidin/ferroportin 1 (FPN1)-mediated iron efflux and resulted in cellular iron deficiency, which led to the functional accumulation of the dopamine transporter (DAT) in plasma membranes due to iron deficiency-impaired ubiquitin degradation. Notably, iron-deficient mice generated via a low iron diet mimicked the effect of Rox on the prevention of Mor- or METH-CPP formation, without affecting other types of memory. These data reveal a novel mechanism for HIF-1α and iron involvement in substance use disorder, which may represent a potential novel therapeutic strategy for the treatment of drug abuse. The findings also repurpose Rox by suggesting a potential new indication for the treatment of substance use disorder.

Adipose-Derived Stem Cells Improve Angiogenesis and Lymphangiogenesis in a Hypoxic Dermal Regeneration Model In Vitro.

Background and Objectives: Impaired wound healing represents an unsolved medical issue with a high impact on patients' quality of life and global health care. Even though hypoxia is a significant limiting factor for wound healing, it reveals stimulating effects in gene and protein expression at cellular levels. In particular, hypoxically treated human adipose tissue-derived stem cells (ASCs) have previously been used to stimulate tissue regeneration. Therefore, we hypothesized that they could promote lymphangiogenesis or angiogenesis. Materials and Methods: Dermal regeneration matrices were seeded with human umbilical vein endothelial cells (HUVECs) or human dermal lymphatic endothelial cells (LECs) that were merged with ASCs. Cultures were maintained for 24 h and 7 days under normoxic or hypoxic conditions. Finally, gene and protein expression were measured regarding subtypes of VEGF, corresponding receptors, and intracellular signaling pathways, especially hypoxia-inducible factor-mediated pathways using multiplex-RT-qPCR and ELISA assays. Results: All cell types reacted to hypoxia with an alteration of gene expression. In particular, vascular endothelial growth factor A (VEGFA), vascular endothelial growth factor B (VEGFB), vascular endothelial growth factor C (VEGFC), vascular endothelial growth factor receptor 1 (VEGFR1/FLT1), vascular endothelial growth factor receptor 2 (VEGFR2/KDR), vascular endothelial growth factor receptor 3 (VEGFR3/FLT4), and prospero homeobox 1 (PROX1) were overexpressed significantly depending on upregulation of hypoxia-inducible factor 1 alpha (HIF-1a). Moreover, co-cultures with ASCs showed a more intense change in gene and protein expression profiles and gained enhanced angiogenic and lymphangiogenic potential. In particular, long-term hypoxia led to continuous stimulation of HUVECs by ASCs. Conclusions: Our findings demonstrated the benefit of hypoxic conditioned ASCs in dermal regeneration concerning angiogenesis and lymphangiogenesis. Even a short hypoxic treatment of 24 h led to the stimulation of LECs and HUVECs in an ASC-co-culture. Long-term hypoxia showed a continuous influence on gene expressions. Therefore, this work emphasizes the supporting effects of hypoxia-conditioned-ASC-loaded collagen scaffolds on wound healing in dermal regeneration.

Tissue Inhibitors of Metalloproteinases 1 Confers 5-Fluorouracil Resistance and Stemness of Gastric Cancer Cells via the Up-Regulation of Hypoxia-Inducible Factor-1α

The role and potential mechanism of TIMP1 in resistance to 5-Fluorouracil (5-Fu) and stem properties in gastric cancer (GC) were investigated. The expressions of HIF-1α and TIMP1, as well as the chemosensitivity of the 5-Fu in GC cell lines (GCCL) (e.g., MGC-803, BGC-823, SGC-7901, HGC-27 and AGS) upon normoxia or hypoxia were analyzed by means of RT-PCR and CCK-8 assay, respectively. Meanwhile, the population of stem cells was determined by using sphere formation assay, while stem cell markers (SCM) (Oct4 and CD44) were detected by western blot to evaluate stem properties. Hypoxia led to upregulated expression of HIF-1α and TIMP1, and enhanced resistance to 5-Fu, sphere formation capability, and expression of SCM in GC cells (GCCs). Indeed, the expressions of TIMP1 and HIF-1α were positively related to each other. The protein levels of both HIF-1α and TIMP1 were increased and decreased by overexpressing and silencing TIMP1, respectively. Under hypoxia conditions, overexpression of TIMP1 conferred 5-Fu-resistance and stem properties to MGC-803 and AGS cells, as revealed by increased IC50 value of 5-Fu, enhanced sphere formation, and up-regulation of Oct4 and CD44; silencing TIMP1 caused the contrary results. TIMP1 is an effective regulator of HIF-1 and plays a critical role in resistance to 5-Fu and stem properties in GCCs upon hypoxia.

HIF2α activation and mitochondrial deficit due to iron chelation cause retinal atrophy

Iron accumulation causes cell death and disrupts tissue functions, which necessitates chelation therapy to reduce iron overload. However, clinical utilization of deferoxamine (DFO), an iron chelator, has been documented to give rise to systemic adverse effects, including ocular toxicity. This study provided the pathogenic and molecular basis for DFO‐related retinopathy and identified retinal pigment epithelium (RPE) as the target tissue in DFO‐related retinopathy. Our modeling demonstrated the susceptibility of RPE to DFO compared with the neuroretina. Intriguingly, we established upregulation of hypoxia inducible factor (HIF) 2α and mitochondrial deficit as the most prominent pathogenesis underlying the RPE atrophy. Moreover, suppressing hyperactivity of HIF2α and preserving mitochondrial dysfunction by α‐ketoglutarate (AKG) protects the RPE against lesions both in vitro and in vivo. This supported our observation that AKG supplementation alleviates visual impairment in a patient undergoing DFO‐chelation therapy. Overall, our study established a significant role of iron deficiency in initiating DFO‐related RPE atrophy. Inhibiting HIF2α and rescuing mitochondrial function by AKG protect RPE cells and can potentially ameliorate patients' visual function.

Second International Pulmonary Hypertension/Heart Failure Symposium—Structural heart disease, right ventricular dysfunction, and stem cell therapy: The European Pediatric Pulmonary Vascular Disease Network

Second International Pulmonary Hypertension/Heart Failure Symposium—Structural heart disease, right ventricular dysfunction, and stem cell therapy: The European Pediatric Pulmonary Vascular Disease Network

3D matrix promotes cell dedifferentiation into colorectal cancer stem cells via integrin/cytoskeleton/glycolysis signaling

The potential for tumor occurrence triggered by cancer stem cells (CSCs) has emerged as a significant challenge for human colorectal cancer therapy. However, the underlying mechanism of CSC development remains controversial. Our study provided evidence that the bulk of tumor cells could dedifferentiate to CSCs and reacquire CSC-like phenotypes if cultured in the presence of extracellular matrix reagents, such as Matrigel and fibrin gels. In these 3D gels, CD133- colorectal cancer cells can regain tumorigenic potential and stem-like phenotypes. Mechanistically, the 3D extracellular matrix could mediate cytoskeletal F-actin bundling through biomechanical force associated receptors integrin β1 (ITGB1), contributing to the release of E3 ligase tripartite motif protein 11 (TRIM11) from cytoskeleton and degradation of the glycolytic rate-limiting enzyme phosphofructokinase (PFK). Consequently, PFK inhibition resulted in enhanced glycolysis and upregulation of hypoxia-inducible factor 1 (HIF1α), thereby promoting the reprogramming of stem cell transcription factors and facilitating tumor progression in patients. This study provided novel insights into the role of the extracellular matrix in the regulation of CSC dedifferentiation in a cytoskeleton/glycolysis-dependent manner.

Modeling the role of HIF in the regulation of metabolic key genes LDH and PDH: Emergence of Warburg phenotype

AbstractOxygenation of tumors and the effect of hypoxia on cancer cell metabolism is a widely studied subject. Hypoxia‐inducible factor (HIF), the main actor in the cell response to hypoxia, represents a potential target in cancer therapy. HIF is involved in many biological processes such as cell proliferation, survival, apoptosis, angiogenesis, iron metabolism, and glucose metabolism. This protein regulates the expressions of lactate dehydrogenase (LDH) and pyruvate dehydrogenase (PDH), both essential for the conversion of pyruvate to be used in aerobic and anaerobic pathways. HIF upregulates LDH, increasing the conversion of pyruvate into lactate which leads to higher secretion of lactic acid by the cell and reduced pH in the microenvironment. HIF indirectly downregulates PDH, decreasing the conversion of pyruvate into acetyl coenzyme A, which leads to reduced usage of the tricarboxylic acid (TCA) cycle in aerobic pathways. Upregulation of HIF may promote the use of anaerobic pathways for energy production even in normal extracellular oxygen conditions. Higher use of glycolysis even in normal oxygen conditions is called the Warburg effect. In this paper, we focus on HIF variations during tumor growth and study, through a mathematical model, its impact on the two metabolic key genes PDH and LDH, to investigate its role in the emergence of the Warburg effect. Mathematical equations describing the enzyme regulation pathways were solved for each cell of the tumor represented in an agent‐based model to best capture the spatio‐temporal oxygen variations during tumor development caused by cell consumption and reduced diffusion inside the tumor. Simulation results show that reduced HIF degradation in normoxia can induce higher lactic acid production. The emergence of the Warburg effect appears after the first period of hypoxia before oxygen conditions return to a normal level. The results also show that targeting the upregulation of LDH and the downregulation of PDH could be relevant in therapy.

Pharmacological Activation of the HIF Pathway Exerts Distinct Proliferative Effects in MDA‐MB‐231 and MCF7 cells**

Hypoxia-mimicking agents (HMAs) exert distinct proliferative effect on breast cancer cells depending on the subtype. Pharmacological HIF activation via PHD inhibition enhances the proliferation rate of triple negative MDA-MB-231 cells but inhibits proliferation of receptor-positive MCF7 cells. Therefore, clinical PHD inhibitors should be used with caution as they may be a double-edged sword, acting as anticancer agents or tumorigenic drivers depending on the breast cancer subtype.

Anesthetic concerns in recipients of hematopoietic stem cell transplant.

Dear Editor, Since the advent of bone marrow transplant in 1957, our understanding of the biology behind Hematopoietic Stem Cell Transplant (HSCT) has improved[1] and almost 50,000 HSCT take place globally in a year.[2] Although anesthetic concerns of patients undergoing solid organ transplantation have been addressed, there is a dearth of literature relating to HSCT, especially after the recent advancements like targeted therapy.[3,4] HSCT entails the regeneration of different blood cell lineages from donor stem cells and embarks on the interplay between recipient T lymphocytes, natural killer (NK) cells and donor antigen presenting cells (APC) and lymphocytes. Allogenic transplant brings forth graft vs. tumor effect (GVT) which helps to prevent recurrences but is shadowed by the graft vs. host disease (GVHD), necessitating chronic immunosuppression. Post HSCT patients are at increased risk of opportunistic infections, especially before engraftment and subtle signs of infections may be missed in the preoperative period as well as there may be delayed wound healing after surgery. While exaggerated increase in host immunity may enhance GVHD, overt diminution by immunosuppressant may lead to secondary infections and reactivation of cytomegalovirus. Therefore, it is prudent to delay elective surgeries before engraftment and while the patient is on immune-modulators.[5] Moreover, anesthesiologist should be aware of long-term adverse effects of chemotherapeutic drugs including potential difficult airway due to gum hypertrophy (cyclosporine) and lymph node enlargement as part of post-transplant lymphoproliferative disorder (PTLD). Acute GVHD may involve different organ systems, leading to potentially dreaded complications like acute lung injury, veno-occlusive disease of liver, thrombotic micro angiopathy (TMA) which should be evaluated during the pre-anesthetic check-up.[5] Surgical stress leads to a temporary state of immunosuppression via various mechanisms like raised catecholamines, angiogenic factors, matrix metalloproteinases (MMPs) and attenuated NK cell activity and cell mediated immunity (CMI). Volatile agents, especially isoflurane may promote tumor growth and spread by reducing NK cell activity, T cell depletion, increased angiogenesis by up-regulation of hypoxia inducible factor (HIF-1 alpha), whereas N2O causes bone marrow suppression. However, sevoflurane was found to stabilize the anti-cancer gene P38. Similar to inhaled agents, ketamine and thiopentone induces T cell apoptosis and NK cell underactivity. Propofol appears to be beneficial by reducing angiogenesis and maintaining T cell activity. Despite report showing impairment of macrophage-monocyte function, midazolam appears to be safer. Action of muscle relaxants may get prolonged due to immunomodulators like cyclosporine, as seen in renal transplant recipients.[6] Although anecdotal reports showed that IV opioids reduced NK cell, T cell and TLR (Toll like Receptor) activity on macrophage, it might enhance tumor lysis by stabilizing P53 and P38 and induce tumor death via NF-kB (nuclear factor kappa beta) and Fas-FasL pathway. Thus, immunomodulating effects of opioids are dose and concentration dependent and judicial perioperative analgesia by opioids seems logical.[7] Whenever feasible, use of regional anesthesia must be emphasized as local anesthetics increase local NK cell activity. Propofol along with paravertebral block have been found to be associated with reducing tumor burden in ER-negative breast cancer. Specific concerns of immune-modulators are provided in Table 1 and perioperative concerns are summarized in Table 2.Table 1: Side effects of commonly used agents and their concernsTable 2: Perioperative concerns in a nutshellInduction by propofol/etomidate, followed by maintenance with total intravenous anesthesia (TIVA) with propofol, intermediate acting muscle relaxants with minimal organ dependent metabolism (e.g., atrcurium, cisatracurium) and use of regional anesthesia may be considered as preferred techniques of choice. With the growing number of HSCTs, the authors feel the need for renewed interest and good quality research in this area. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

Hypoxia-induced HIF-1α/lncRNA-PMAN inhibits ferroptosis by promoting the cytoplasmic translocation of ELAVL1 in peritoneal dissemination from gastric cancer

Peritoneal metastasis (PM) is the main site of gastric cancer (GC) distant metastasis and indicates an extremely poor prognosis and survival. Hypoxia is a common feature of peritoneal metastases and up-regulation of hypoxia inducible factor 1 alpha (HIF-1α) may be a potential driver in the occurrence of PM. Ferroptosis is a recently discovered form of regulated cell death and closely related to the occurrence and development of tumors. However, the underlying mechanism link HIF-1α to ferroptosis in PM of GC remains unknown. Here, lncRNA-microarrays and RNA library construction/lncRNA-seq results shown that lncRNA-PMAN was highly expressed in PM and significantly modulated by HIF-1α. Upregulation of PMAN is associated with poor prognosis and PM in patients with GC. PMAN was up-regulated by HIF-1α and improved the stability of SLC7A11 mRNA by promoting the cytoplasmic distribution of ELAVL1, which was identified in RNA-pulldown/mass spectrometry results. Accumulation of SLC7A11 increases the level of l-Glutathione (GSH) and inhibits the accumulation of reactive oxygen species (ROS) and irons in the GC cells. Finally protect GC cells against ferroptosis induced by Erastin and RSL3. Our findings have elucidated the effect of HIF-1α/PMAN/ELAVL1 in GC cells ferroptosis and provides theoretical support for the potential diagnostic biomarkers and therapeutic targets for PM in GC.

Dietary arginine attenuates hypoxia- induced HIF expression, metabolic responses and oxidative stress in Indian Major Carp, Cirrhinus mrigala.

Hypoxia is a common stressor in aquaculture systems, which causes severe physiological disturbances, ultimately leading to mortality or reduced productivity. Arginine, as a precursor of NO, has a role in enhancing oxygen delivery. Thus, an experiment was conducted to evaluate the effect of dietary arginine (Arg) in Cirrhinus mrigala exposed to hypoxia. The fish were fed with different levels of arginine for 60days and exposed for 72h to a sublethal level of hypoxia (0.50±0.16mg/L dissolved oxygen [DO]). The six treatment groups with three replicates were N0 (0% Arg+Normoxia), H0 (0% Arg+Hypoxia), N0.7 (0.70% Arg+Normoxia), H0.7 (0.70% Arg+Hypoxia), N1.4 (1.40% Arg+Normoxia), H1.4 (1.40% Arg+Hypoxia). Eighteen experimental units with twelve animals (5.8±0.18g) each were used for the trial.The results indicated that supplementation of arginine at 0.7 and 1.4% enhanced the hypoxia tolerance time, although the high dose (1.4%) did not yield any further increments. The exposure to hypoxia up-regulated Hypoxia Inducible Factor (HIF)-1α mRNA expression and supplementation of arginine significantly decreased hypoxia induced up-regulation of HIF at 1.4%. Arginine supplementation partially or completely normalised the hypoxia induced changes in the metabolic enzymes of C. mrigala. The fish exposed to hypoxic conditions exhibited significantly higher (P<0.05) lipid peroxidation levels than those maintained under normoxic conditions, while arginine feeding significant in reducing lipid peroxidation. Antioxidant enzyme activities were significantly higher (P<0.05) in hypoxia-exposed carp, indicating increased oxidative stress during the hypoxic exposure, that was improved in Arg-supplemented groups. However, arginine did not modulate erythrocyte countsalthough itreduced the erythrocyte fragility. We conclude arginine supplementation is effective in ameliorating hypoxia induced metabolic alterations and improving antioxidant defences in fish.

Gene expression of hypoxia-inducible factor (HIF), HIF regulators, and putative HIF targets in ventricle and telencephalon of Trachemys scripta acclimated to 21 °C or 5 °C and exposed to normoxia, anoxia or reoxygenation

In anoxia-sensitive mammals, hypoxia inducible factor (HIF) promotes cellular survival in hypoxia, but also tumorigenesis. By comparison, anoxia-tolerant vertebrates likely need to circumvent a prolonged upregulation of HIF to survive long-term anoxia, making them attractive biomedical models for investigating HIF regulation. To lend insight into the role of HIF in anoxic Trachemys scripta ventricle and telencephalon, 21 °C- and 5 °C-acclimated turtles were exposed to normoxia, anoxia (24 h at 21 °C; 24 h or 14 d at 5 °C) or anoxia + reoxygenation and the gene expression of HIF-1α (hif1a) and HIF-2α (hif2a), two regulators of HIF, and eleven putative downstream targets of HIF quantified by qPCR. Changes in gene expression with anoxia at 21 °C differentially aligned with a circumvention of HIF activity. Whereas hif1a and hif2a expression was unaffected in ventricle and telencephalon, and BCL2 interacting protein 3 gene expression reduced by 30% in telencephalon, gene expression of vascular endothelial growth factor-A increased in ventricle (4.5-fold) and telencephalon (1.5-fold), and hexokinase 1 (2-fold) and hexokinase 2 (3-fold) gene expression increased in ventricle. At 5 °C, the pattern of gene expression in ventricle or telencephalon was unaltered with oxygenation state. However, cold acclimation in normoxia induced downregulation of HIF-1α, HIF-2α, and HIF target gene expression in telencephalon. Overall, the findings lend support to the postulation that prolonged activation of HIF is counterproductive for long-term anoxia survival. Nevertheless, quantification of the effect of anoxia and acclimation temperature on HIF binding activity and regulation at the protein level are needed to provide a strong scientific framework whereby new strategies for oxygen related pathologies can be developed.

The Role of Hypoxia in Endometrial Cancer.

Endometrial cancer represents the most frequent neoplasia from the corpus uteri and comprises the 14th leading cause of death in women worldwide. Risk factors that contribute to the disease include early menarche, late menopause, nulliparity, and menopausal hormone use, as well as hypertension and obesity comorbidities. The clinical effectiveness of chemotherapy is variable, suggesting that novel molecular targeted therapies against specific cellular processes associated with the maintenance of cancer cell survival and therapy resistance ameliorate the rates of success in endometrial cancer treatment. In the course of tumor growth, cancer cells must adapt to decreased oxygen availability in the microenvironment by upregulation of hypoxia-inducible factors, which orchestrate the activation of a transcriptional program leading to cell survival. During this adaptative process, the hypoxic cancer cells may acquire invasive and metastatic properties as well as increased cell proliferation and resistance to chemotherapy, enhanced angiogenesis, vasculogenic mimicry, and maintenance of cancer cell stemness, which contribute to more aggressive cancer phenotypes. Several studies have shown that hypoxia-inducible factor 1 alpha (HIF-1α) protein is aberrantly overexpressed in many solid tumors of the breast, prostate, ovarian, bladder, colon, brain, and pancreas. Thus, it has been considered an important therapeutic target. Here, we reviewed the current knowledge of the relevant roles of cellular hypoxia mechanisms and HIF-1α functions in diverse processes associated with endometrial cancer progression. In addition, we also summarize the role of microRNAs in the posttranscriptional regulation of protein-encoding genes involved in the hypoxia response in endometrial cancer. Finally, we pointed out the need for urgent targeted therapies to impair the cellular processes activated by hypoxia in the tumor microenvironment.

The effect of PHD inhibitor on tumor microenvironment and tumor immune response.

Since the approval of PHD inhibitors, PHD inhibitors have been used clinically, and many studies and clinical case reports have been reported in Japan. A lot of information has been accumulated on clinical usage. However, PHD inhibitors require careful administration for cancer patients due to their action mechanism through upregulate hypoxia-inducible factors (HIFs) level. In cancer cells, HIFs affect to tumor progression and contribute to chemo- and radio- resistance. On the other hand, upregulation of HIFs in immune cells is associated with inflammation and affected to suppress tumor progression. Although these controversial effects are not clear in vivo model. It is needed to reveal whether upregulating HIFs level is beneficial for cancer therapy or not. We have previously reported that PHD inhibitor treatment in tumor bearing mice model led to reconstitute tumor blood vessels and inhibit tumor growth. In addition, these phenomena caused of tumor infiltrated macrophages and altered these phenotypes. In this session, we will describe our findings on the mechanism of tumor growth suppression by PHD inhibitors. We will also discuss about the risks and benefits of PHD inhibitors.

Visualizing nitric oxide-dependent HIF-1 activity under hypoxia with a lipid droplet-targeting fluorescent probe

Evaluating the correlation between hypoxia inducible factor 1 (HIF-1) and nitric oxide (NO) generated under hypoxia is of great significance. In this work, we developed a fluorescent probe for the monitor of HIF-1 activity influenced by NO under hypoxia in hepatoma cells with dual-targeting for hepatocyte and lipid droplet (LD). The probe shows excellent selectivity to NO and high sensitivity with 6000-fold fluorescence enhancement. Live cell imaging experiments revealed the probe's capability of imaging exogenous and endogenous NO with specific in LDs of HepG2 cells. For cells under hypoxia, HIF-1 induced LD level is observed to correlate with NO level. This work provides the in-situ visualization of NO-dependent HIF-1 upregulation through LD accumulation.

Selenomethionine protects hematopoietic stem/progenitor cells against cobalt nanoparticles by stimulating antioxidant actions and DNA repair functions.

Hematopoietic stem cells (HSCs) and hematopoietic progenitor cells (HPCs) can differentiate into all blood lineages to maintain hematopoiesis, wound healing, and immune functions. Recently, cobalt-chromium alloy casting implants have been used extensively in total hip replacements; however, cobalt nanoparticles (CoNPs) released from the alloy were toxic to HSCs and HPCs. We aimed to investigate the mechanism underlying the toxic effect of CoNPs on HSCs/HPCs and to determine the protective effect of selenomethionine (SeMet) against CoNPs in vitro and in vivo. Human and rat CD34+ HSCs/HPCs were isolated from cord blood and bone marrow, respectively. CoNPs decreased the viability of CD34+ HSCs/HPCs and increased apoptosis. SeMet attenuated the toxicity of CoNPs by enhancing the antioxidant ability of cells. The protective effect of SeMet was not completely abolished after adding H2O2 to abrogate the improvement of the antioxidant capacity by SeMet. SeMet and CoNPs stimulated ATM/ATR DNA damage response signals and inhibited cell proliferation. Unlike CoNPs, SeMet did not damage the DNA, and cell proliferation recovered after removing SeMet. SeMet inhibited the CoNP-induced upregulation of hypoxia inducible factor (HIF)-1α, thereby disrupting the inhibitory effect of HIF-1α on breast cancer type 1 susceptibility protein (BRCA1). Moreover, SeMet promoted BRCA1-mediated ubiquitination of cyclin B by upregulating UBE2K. Thus, SeMet enhanced cell cycle arrest and DNA repair post-CoNP exposure. Overall, SeMet protected CD34+ HSCs/HPCs against CoNPs by stimulating antioxidant activity and DNA repair.