Hypoxia-inducible Factor Research Articles

Role of Protein Ubiquitination and HIF Signaling in the Evolution of Hypoxic Breast Cancer.

Alternations in protein ubiquitination along with hypoxia-inducible factor (HIF) signaling contribute to tumorigenesis and breast tumor advancement. Ubiquitination is an impulsive process, which is coordinately governed by E3 ligases and deubiquitinases (DUBs), that have come out as charismatic therapeutic targets. HIF expression, as well as the transcriptional process in malignancies, are frequently elevated, resulting in pitiable clinical outcomes. According to increasing research, multiple E3 ligases, in addition to UBDs work together to modulate HIF expression and activity, permitting breast cancer cells to make out a hypoxic milieu. On the other hand, hypoxia and HIF signaling regulate numerous E3 ligases as well as DUBs. Interpreting involved networks connecting E3 ligase, DUBS, and HIF will reveal profound mechanisms of physiological response to hypoxia and aid in the discovery of new molecular references for cancer management. The present state of knowledge about the entire kinship among E3 ligase, DUBs, and HIF signaling is reviewed here, emphasizing using E3 ligase or DUB inhibitors in breast cancer.

Innovative Nanomaterials for Targeting Hypoxia to Improve Treatment for Triple-negative Breast Cancer.

Triple-negative breast cancer (TNBC) is an aggressive breast cancer with a high rate of metastases, a short overall survival time, and a poor response to targeted therapy. Improving tumor hypoxia by lowering the oxygen consumption rate of breast tumor cells is a powerful strategy. A viable way to address this issue is to improve therapeutic efficacy by improving the effectiveness of radiation and overcoming drug resistance in TNBC treatment by controlling hypoxia in the tumor microenvironment. The failure of radiation and chemotherapy in TNBC is frequently caused by hypoxia. In TNBC therapy, novel nanomaterials are used for oxygen delivery or generation to affect the tumor microenvironment to improve the effects of ionizing radiation using nanoplatforms. One of the growing fields is novel nano-based drug delivery devices for hypoxic regions and hypoxia- inducible factor-1 (HIF1) targeted therapeutics. Biocompatible nanoparticles may be used in the treatment of TNBC patients in the clinic. Because of the rising market and competition, intellectual property rights (IPR), patents, and tactics may be critically considered. To better comprehend the current state of IPR and patents in cancer nanotechnology, this overview examines recent advances and sophisticated protection measures in this area.

Empagliflozin protects the heart from atrial fibrillation in rats through inhibiting the NF-κB/HIF-1α regulatory axis and atrial remodeling

Atrial fibrillation (AF) is the most common form of sustained cardiac arrhythmia. The current study aimed to investigate the potential of empagliflozin (EMPA) to protect against acetylcholine (ACh)/calcium chloride (CaCl2)-induced AF in rats and elucidate the possible underlying mechanism of action. Rats were randomly assigned to five groups, as follows: CTRL group: received 1 ml/kg isotonic saline; AF group: received 1 ml/kg induction mixture of ACh/CaCl2 (60 µg ACh and 10 mg CaCl2 per ml); EMPA group: received 30 mg/kg EMPA; AF + EMPA10 group: received the induction mixture concurrent with 10 mg/kg EMPA; AF + EMPA30 group: received the induction mixture concurrent with 30 mg/kg EMPA. Our results showed that EMPA administration inhibited the AF-related electrocardiographic abnormalities and decreased the serum brain natriuretic peptide levels. EMPA treatment maintained the cardiac redox balance, as indicated by reduced levels of the lipid peroxidation biomarker malonaldehyde while enhancing the antioxidant glutathione levels. Moreover, EMPA markedly repressed ACh/CaCl2-induced C-reactive protein, tumor necrosis factor, and interleukin-6 production. Interestingly, EMPA administration strongly suppressed cardiac transforming growth factor beta1, collagen type I, and alpha-smooth muscle actin expression levels in the AF rats. These results were consistent with our histopathological findings, which revealed the ameliorative effect of EMPA on AF-induced inflammatory and fibrotic lesions. Mechanistically, EMPA dose-dependently downregulated nuclear factor-kappa B (NF-κB) and hypoxia-inducible factor (HIF)-1α expressions. Besides, it attenuated the pro-apoptotic active caspase-3 while augmenting the anti-apoptotic B-cell lymphoma 2 expressions. Furthermore, EMPA dose-dependently suppressed cardiac phosphatidylinositol 3-kinase (PI3K)/Akt signaling. In conclusion, this study demonstrates that EMPA intervention, within AF induction, protects against ACh/CaCl2-induced AF in rats, exerting powerful antioxidant, anti-inflammatory, anti-fibrotic, and anti-apoptotic effects. These effects are mainly mediated through the targeting of the NF-κB/HIF-1α regulatory axis in a dose-dependent manner.

Farrerol suppresses epithelial-mesenchymal transition in hepatocellular carcinoma via suppression of TGF-β1/Smad2/3 signaling

BackgroundEpithelial-mesenchymal transition (EMT) is an essential process for the metastasis of multiple malignancies, including hepatocellular carcinoma (HCC). Farrerol is a plant-derived flavonoid and has significant pharmacological effects. However, the anticancer activities of farrerol have not been fully elucidated. Here, we investigated the effects of farrerol on HCC progression. MethodsThe potential of farrerol to prevent HCC cell migration and invasiveness was evaluated by wound healing and transwll matrix assays. Immunoblotting, immunofluorescence, and qPCR were used to detect the levels of EMT-related proteins. Transforming growth factor beta (TGF-β) (10ng/ml) was used to stimulate HCC cells, followed by measurement of cell migration, invasiveness, and the EMT. TGF-β1/Smads signaling was examined by immunoblotting. A xenograft mouse model was used to assess the anticancer efficacy of farrerol in vivo. The expression levels of EMT- and angiogenesis-related proteins in xenograft tumors were evaluated by immunoblotting or immunohistochemistry. ResultsWe found that farrerol blocked HCC cell migration and invasiveness. Farrerol upregulated E-cadherin levels and reduced N-cadherin and vimentin levels. Farrerol also downreuglated the expression levels of EMT-related transcription factors including slug, snail, twist, and zeb1. Furthermore, farrerol suppressed TGF-β-stimulated migration, invasiveness, and the EMT in HCC cells. The phosphorylation of Smad 2/3 induced by TGF-β was inhibited by farrerol. Importantly, farrerol suppressed HCC growth and the EMT in vivo. Farrerol also inhibited tumor angiogenesis by inhibiting hypoxia-inducible factor-1 alpha (HIF-1α) and vascular endothelial growth factor (VEGF) in vivo. ConclusionOverall, farrerol suppresss HCC by inhibiting migration, invasiveness, the EMT, and angiogenesis, implying that farrerol could be a promising antimetastasis agent for HCC.

Novel dysregulated long non-coding RNAs in the acute kidney injury-to-chronic kidney diseases transition unraveled by transcriptomic analysis.

Acute kidney injury (AKI)-to-chronic kidney disease (CKD) transition involves a complex pathomechanism, including inflammation, apoptosis, and fibrosis where long non-coding RNAs (lncRNAs) play a crucial role in their regulation. However, to date, only a few lncRNAs have been discovered to be involved in the AKI-to-CKD transition. Therefore, this study aims to investigate the dysregulated lncRNAs in the AKI-to-CKD transition invitro and invivo. To mimic AKI-to-CKD transition both invivo and invitro, bilateral ischemia-reperfusion (IR) kidney injury was performed in Wistar rats (male), and normal rat kidney epithelial cell (NRK52E) cells were treated with exogenous transforming growth factor-β1 (TGF-β1). Further processing and analysis of samples collected from these studies (e.g., biochemical, histopathology, immunofluorescence, and RNA isolation) were also performed, and transcriptomic analysis was performed to identify the dysregulated lncRNAs. Rats subjected to IR showed a significant increase in kidney injury markers (creatinine, blood urea nitrogen (BUN), kidney injury molecule-1(KIM-1), and neutrophil gelatinase-associated lipocalin (NGAL) along with altered cell morphology). Apoptosis, inflammation, and fibrosis markers were markedly increased during the AKI-to-CKD transition. Furthermore, transcriptomic analysis revealed 62 and 84 unregulated and 95 and 92 downregulated lncRNAs invivo and invitro, respectively. Additionally, functional enrichment analysis revealed their involvement in various pathways, including the tumor necrosis factor (TNF), wingless-related integration site (Wnt), and hypoxia-inducible factor-1 (HIF-1) signaling pathways. These identified dysregulated lncRNAs significantly contribute to AKI-to-CKD transition, and their knockin/out can aid in developing targeted therapeutic interventions against AKI-to-CKD transition.

Progress and perspectives on BMP9-ID1 activation of HIF-1α and VEGFA to promote angiogenesis in hepatic alveolar echinococcosis

Hepatic alveolar echinococcosis is a zoonotic disease with a high incidence in western China, particularly affecting plateau areas such as Qinghai, Tibet, and Xinjiang. Research has indicated the presence of neovascularization in the peripheral infiltration area of hepatic alveolar echinococcosis, with a strong correlation between angiogenesis and vascular endothelial growth factor A (VEGFA) and hypoxia-inducible factor 1-alpha (HIF-1α) overexpression. Given the similarities between hepatic alveolar echinococcosis and liver cancer, current research is focused on treating the disease by targeting related signaling pathways using molecular drugs used for liver cancer. This article aims to summarize the biological regulation of HIF-1α and VEGFA overexpression in angiogenesis related to hepatic alveolar echinococcosis, as well as the impact of the BMP9-ID1 signaling pathway on the expression levels of HIF-1α and VEGFA, providing new insights for potential treatment strategies.

PLAC1 augments the malignant phenotype of cervical cancer through the mTOR/HIF-1α/snail signaling pathway.

This study investigated the molecular mechanisms of placenta-specific protein 1 (PLAC1) in cervical cancer (CCa), aiming to elucidate its role in tumorigenesis through in vitro and in vivo experiments. CCa cell lines with overexpressed or silenced PLAC1 were established to evaluate its impact on cell cycle, apoptosis and the expression of key proteins in the PLAC1/mTOR/HIF-1α/Snail signaling pathways. Functional assays were conducted to assess the influence of the PLAC1/mTOR/HIF-1α/Snail regulatory pathway on cell proliferation, migration and invasion. The role of the mTOR signaling pathway in PLAC1-mediated modulation of CCa characteristics was validated using a mTOR activator (MHY1485) and a mTOR inhibitor (Rapamycin) respectively. HIF1A siRNA was introduced to confirm the role of HIF1A. Furthermore, an in vivo nude mouse model was constructed to confirm PLAC1's influence on tumorigenesis and metastasis in CCa. PLAC1 upregulated hypoxia-inducible factor (HIF)-1α and Snail, promoting CCa cell proliferation, migration, and invasion via the mTOR/HIF-1α/Snail pathway. Enrichment analysis of PLAC1-associated differentially expressed genes implicated their involvement in CCa and tumor promotion. In a xenograft mouse model, PLAC1 exhibited a pro-tumorigenic effect, which can be reversed by siRNA targeting HIF1A. This study enhances our understanding of PLAC1's role and molecular mechanisms in CCa progression, highlighting its potential as a diagnostic, prognostic, and therapeutic marker for the management of CCa.

Metabolic rewiring controlled by HIF-1α tunes IgA-producing B-cell differentiation and intestinal inflammation.

Germinal centers where B cells undergo clonal expansion and antibody affinity maturation are hypoxic microenvironments. However, the function of hypoxia-inducible factor (HIF)-1α in immunoglobulin production remains incompletely characterized. Here, we demonstrated that B cells lacking HIF-1α exhibited significantly lower glycolytic metabolism and impaired IgA production. Loss of HIF-1α in B cells affects IgA-producing B-cell differentiation and exacerbates dextran sodium sulfate (DSS)-induced colitis. Conversely, promoting HIF-1α stabilization via a PHD inhibitor roxadustatenhances IgA class switching and alleviates intestinal inflammation. Mechanistically, HIF-1α facilitates IgA class switching through acetyl-coenzyme A (acetyl-CoA) accumulation, which is essential for histone H3K27 acetylation at the Sα region. Consequently, supplementation with acetyl-CoA improved defective IgA production in Hif1a-deficient B cells and limited experimental colitis. Collectively, these findings highlight the critical importance of HIF-1α in IgA class switching and the potential for targeting the HIF-1α-dependent metabolic‒epigenetic axis to treat inflammatory bowel diseases and other inflammatory disorders.

Hypoxia-reducedYAP phosphorylation enhances expression of Mucin5AC in nasal epithelial cells of chronic rhinosinusitis with nasal polyps.

Chronic rhinosinusitis with nasal polyps (CRSwNP) is an upper respiratory disease characterized by persistent inflammation of the nasal mucosa. However, the mechanism of abnormal Mucin5AC expression by CRSwNP epithelial cells is not fully understood. We investigated the potential role of yes-associated protein (YAP) underlying the mechanism of excessive epithelial Mucin5AC expression in CRSwNP in a hypoxic model. Tissue biopsies of CRSwNP (n = 60), chronic rhinosinusitis without nasal polyps (CRSsNP) (n = 9) and healthy controls (n = 30) were investigated together with a well-established hypoxic model of primary human nasal epithelial cells (hNECs). The expression levels of hypoxia inducible factor (HIF)-1α and YAP, and the effect of the signaling axis on mucus secretion in hNECs were analyzed. We observed a significant elevated expression levels of YAP in patients with CRSwNP and CRSsNP compared to controls. In addition, HIF-1α expression of CRSwNP was higher than that of control group. Under hypoxic conditions, HIF-1α was found to regulate the upregulation of YAP in hNECs. Further investigations revealed that HIF-1α facilitated the activation and nuclear localization of active-YAP by reducing the phosphorylation of YAP. This mechanism appeared to be linked to HIF-1α-mediated inhibition of LATS 1 phosphorylation and subsequent YAP degradation. HIF-1α was shown to promote the expression of P63 and the levels of Mucin5AC in hNECs by enhancing YAP activation. Our findings indicated that hypoxia enhances YAP activation by decreasing p-LATS 1 and YAP phosphorylation. This has the potential to impact on the proliferation of basal cells and the differentiation of goblet cells in CRSwNP, ultimately leading to a pathological condition characterized by excessive Mucin5AC expression.

EHD1 promotes breast cancer metastasis through upregulating HIF2a expression via activating mTOR pathway.

The multistep dynamic process of metastasis is the primary cause of breast cancer deaths. C-terminal Eps15-homology domain-containing protein 1 (EHD1), a translocator associated with endocytic recycling, has been implicated in various oncogenic processes. However, the precise molecular mechanisms of EHD1-induced breast cancer metastases remain largely unexplored. Here we found that the upregulation of EHD1 in breast cancer was positively associated with distant lymph node metastasis in patients. Meanwhile, EHD1 promoted epithelial-mesenchymal transition (EMT), invasion, and metastasis of breast cancer cells in both two-dimensional (2D) and three-dimensional (3D) culture models invitro, as well as invivo. Remarkably, EHD1 can activate the AKT-mTOR pathway to upregulate the protein expression of hypoxia-inducible factor 2α (HIF2α) under normoxic conditions and subsequently enhance the invasive and metastatic breast cancer. Our findings indicated EHD1 as a new regulator of HIF2α and a potential therapeutic target for inhibiting breast cancer metastasis.

Potential Roles of Hypoxia-Inducible Factor-1 in Alzheimer’s Disease: Beneficial or Detrimental?

The major pathological characteristics of Alzheimer’s disease (AD) include senile plaques and neurofibrillary tangles (NFTs), which are mainly composed of aggregated amyloid-beta (Aβ) peptide and hyperphosphorylated tau protein, respectively. The excessive production of reactive oxygen species (ROS) and neuroinflammation are crucial contributing factors to the pathological mechanisms of AD. Hypoxia-inducible factor-1 (HIF-1) is a transcription factor critical for tissue adaption to low-oxygen tension. Growing evidence has suggested HIF-1 as a potential therapeutic target for AD; conversely, other experimental findings indicate that HIF-1 induction contributes to AD pathogenesis. These previous findings thus point to the complex, even contradictory, roles of HIF-1 in AD. In this review, we first introduce the general pathogenic mechanisms of AD as well as the potential pathophysiological roles of HIF-1 in cancer, immunity, and oxidative stress. Based on current experimental evidence in the literature, we then discuss the possible beneficial as well as detrimental mechanisms of HIF-1 in AD; these sections also include the summaries of multiple chemical reagents and proteins that have been shown to exert beneficial effects in AD via either the induction or inhibition of HIF-1.

TMIC-20. UNLOCKING THE POTENTIAL OF HYPOXIA REDUCTION IN RESHAPING THE GLIOBLASTOMA TUMOR MICROENVIRONMENT FOR ENHANCED THERAPEUTIC SYNERGY

Abstract Glioblastoma (GBM) tumors respond poorly to nearly all cancer therapies due to their highly immunosuppressive tumor microenvironment (TME). Hypoxia exacerbates this immunosuppression by upregulating the hypoxia-inducible factor (HIF) pathway in glioma-associated myeloid cells (GAMs) which suppressively polarizes them to maintain this immune “cold” state. This hypoxia-driven programming inhibits CD8+ T cell infiltration and effector function by inducing metabolic dysfunction, thereby increasing resistance to chemotherapy and T cell immune checkpoint blockade (ICB). Targeting hypoxia thus emerges as a promising strategy to overcome such resistance. Our study suggests that GBM hypoxia ablation can convert the immunosuppressive tumor microenvironment into a more pro-inflammatory one. Tumor hypoxia ablation using the hypoxia-activated prodrug Evofosfamide significantly enhances survival in both GL261 (p<0.0001) and the checkpoint blockade-resistant CT2A murine GBM models (p<0.01). Evofosfamide treatment boosts tumor infiltrating Ki67+ proliferative CD8+ T cells (p<0.001) and heightens cytotoxicity, indicated by increased Granzyme B expression (p<0.01). It also reduces the co-expression of exhaustion markers LAG-3 and TIM-3 (p<0.001), signaling decreased T cell exhaustion. Antigen-specific CD8+ T cells from Evofosfamide-treated primary GBM tumors exhibit enhanced ex vivo killing capacity when co-cultured with GL261-OVA cells (p<0.001). Furthermore, Evofosfamide enhances microglia proliferation and repolarizes them towards a pro-inflammatory state, marked by upregulation of M1 markers such as CD80 (p<0.001) and downregulation of M2 markers like Arginase (p<0.05). Hypoxia reduction also increases chemotherapy sensitivity, synergistically improving survival when combined with the blood-brain barrier-penetrating, immunogenic chemotherapy Berubicin (CT2A; vehicle MS=26d, Evo MS=36d, Berubicin MS=55d, Combo MS=70.5d). Future research will investigate the mechanisms underlying this shift towards a pro-inflammatory state, focusing on metabolic changes in CD8+ T cells and the impact of altered HIF pathway signaling on GAM polarization following hypoxia ablation. Understanding the therapeutic potential of reversing hypoxia-mediated immunosuppression could lead to novel combination therapies capable of overcoming resistance to both chemotherapy and immunotherapy in GBM.

CSIG-14. ACROLEIN INDUCES THE MIR-30A-5P/NCAM AXIS THROUGH THE AKT/GSK3Β/Β-CATENIN PATHWAY, PROMOTING GLIOMA PROGRESSION

Abstract Glioblastoma (GBM), the most aggressive brain tumor, exhibits resistance to treatment and thrives in low-oxygen (hypoxic) environments, leading to the accumulation of reactive oxygen species (ROS). Hypoxia activates the hypoxia-inducible factor (HIF)-1α pathway, enhancing tumor malignancy. Acrolein, a reactive aldehyde produced during lipid peroxidation in hypoxia, induces toxicity through DNA damage, inflammation, mitochondrial dysfunction, and oxidative stress. Our previous study found elevated acrolein levels in hypoxic glioma cells and linked acrolein-induced DNA damage (Acr-dG) with poor GBM prognosis. However, the role of acrolein in GBM progression remains unclear. This study aims to elucidate the impact of acrolein on GBM. In vitro experiments demonstrated acrolein production under hypoxia, which increased glioma cell migration and spheroid formation. RNA sequencing identified five affected pathways: cell adhesion molecules, PI3K-AKT signaling, ECM-receptor interaction, MAPK signaling, and neuroactive ligand-receptor interaction. Acrolein downregulated NCAM (neural cell adhesion molecule) via the miR-30a-5p-AKT-GSK3β/β-catenin axis in GBM cell lines and patient-derived cells. Overexpressing NCAM reduced cell migration and spheroid formation. Lower NCAM levels in GBM tissues correlated with poor patient survival. This study suggests the potential of NCAM as a therapeutic target for GBM and provides insights into early detection and treatment strategies for this malignancy.

CSIG-15. ACROLEIN INDUCES THE MIR-30A-5P/NCAM AXIS VIA THE AKT/GSK3Β/Β-CATENIN PATHWAY, PROMOTING GLIOMA PROGRESSION

Abstract Glioblastoma (GBM), the most aggressive brain tumor, exhibits resistance to treatment and thrives in low-oxygen (hypoxic) environments, leading to the accumulation of reactive oxygen species (ROS). Hypoxia activates the hypoxia-inducible factor (HIF)-1α pathway, enhancing tumor malignancy. Acrolein, a reactive aldehyde produced during lipid peroxidation in hypoxia, induces toxicity through DNA damage, inflammation, mitochondrial dysfunction, and oxidative stress. Our previous study found elevated acrolein levels in hypoxic glioma cells and linked acrolein-induced DNA damage (Acr-dG) with poor GBM prognosis. However, the role of acrolein in GBM progression remains unclear. This study aims to elucidate the impact of acrolein on GBM. In vitro experiments demonstrated acrolein production under hypoxia, which increased glioma cell migration and spheroid formation. RNA sequencing identified five affected pathways: cell adhesion molecules, PI3K-AKT signaling, ECM-receptor interaction, MAPK signaling, and neuroactive ligand-receptor interaction. Acrolein downregulated NCAM (neural cell adhesion molecule) via the miR-30a-5p-AKT-GSK3β/β-catenin axis in GBM cell lines and patient-derived cells. Overexpressing NCAM reduced cell migration and spheroid formation. Lower NCAM levels in GBM tissues correlated with poor patient survival. This study suggests the potential of NCAM as a therapeutic target for GBM and provides insights into early detection and treatment strategies for this malignancy.

CTNI-82. BELZUTIFAN TREATMENT OF VHL-ASSOCIATED CENTRAL NERVOUS SYSTEM HEMANGIOBLASTOMA

Abstract Von Hippel-Lindau (VHL) disease is caused by pathogenic variants in the VHL gene. Abnormal function of VHL protein leads to accumulation of HIF-α and the engagement of hypoxia-sensitive genes with oncogenic effects. VHL is associated with tumors in multiple organs. Belzutifan is an oral selective inhibitor of hypoxia-inducible factor 2 alpha. Belzutifan was approved in 2021 as a targeted therapy for VHL-associated CNS hemangioblastomas, renal cell carcinomas, and pancreatic neuroendocrine tumors. Here, we report on our institutional clinical experience with belzutifan for VHL-associated CNS hemangioblastomas. From October 2021 to May 2024, thirteen adults (9 female, 4 male, median age 40) were treated. Median duration of therapy was 24 months. Seven had a partial radiographic response after median of 3 months; one patient had a partial response; 1 patient had progressive disease on belzutifan. Four patients have been taking belzutifan for less than 3 months, and do not have follow-up imaging to assess response. The most common adverse effect was fatigue (7 patients). Four patients experienced anemia and 2 experienced hypoxia. Three patients discontinued belzutifan due to adverse effects. One patient had to take multiple medication pauses, due to seizure and kidney injury, but resumed treatment with dose reduction. Nine patients remain on therapy. Based on this data, belzutifan is often well-tolerated and associated with durable radiographic responses. Toxicity profile among our patients was similar to that encountered in the clinical trial leading to approval of the agent. These findings provide real-world data supporting continued use of belzutifan in this patient population, with an awareness of potential adverse reactions. Future studies should assess continued radiographic response, sex differences, and effects after long-term use.

NIMG-84. BELZUTIFAN REDUCTION OF CEREBRAL BLOOD FLOW IN VHL-ASSOCIATED HEMANGIOBLASTOMA PREDICTS RESPONSE TO TREATMENT

Abstract Hemangioblastoma (HMB) is a vascular-origin tumor occurring primarily in the cerebellum. Treatment typically involves surgical resection of the solid part of the tumor or stereotactic radiosurgery. An emerging treatment for hemangioblastoma is belzutifan (BZF), a hypoxia-inducible factor 2a (HIF2a) inhibitor. A recent trial found BZF to control hemangioblastoma in patients with von Hippel Lindau (vHL) syndrome. Perfusion MRI techniques including arterial spin labelling (ASL) and can be used to determine relative cerebral blood flow (rCBF). No prior studies have investigated rCBF in hemangioblastoma with relation to belzutifan, and the mechanism of action of belzutifan on hemangioblastoma is not well understood. Here, we aim to measure the response in rCBF in patients with vHL-associated hemangioblastoma treated with belzutifan. This retrospective cohort study constituted a group of seven patients with vHL-associated hemangioblastoma treated with Belzutifan at a daily oral dose of 120mg. Perfusion MRI with ASL sequences were acquired as part of the tumor imaging protocol. We quantified rCBF of the tumors prior to treatment, following intiation of BZF, and at most recent follow-up. Statistics were performed using R studio. The long axis diameter, volume of the solid tumor, rCBF mean, rCBF max, N mean, N max of lesions all decreased after Belzutifan treatment (p<0.001). While the long axis diameter of the cyst in cystic lesions did not show statistically significant change, the volume of cysts decreased significantly on Belzutifan (p=0.016). Spearman’s rank correlation analysis demonstrated association between change in rCBF mean, rCBF max, N mean and N max to % reduction in tumor volume. In addition, change in rCBF mean, change in rCBF max and change in N max all showed statistically significant association on multiple linear regression. Finally, early change in CBF and N predicted further volumetric response to treatment with belzutifan. We demonstrate that vHL-associated hemangioblastoma demonstrates decrease in rCBF in conjunction with and predictive of decreased volume following treatment with belzutifan.

NIMG-28. HYPERPOLARIZED13C IMAGING OF D-2-HYDROXYGLUTARATE-INDUCED DOWNREGULATION OF PYRUVATE DEHYDROGENASE ACTIVITY PROVIDES AN EARLY READOUT OF RESPONSE TO VORASIDENIB IN MUTANT IDH GLIOMAS

Abstract Mutations in isocitrate dehydrogenase (IDHm) define a distinct class of gliomas. IDHm converts a-ketoglutarate (a-KG) to D-2-hydroxyglutarate (D-2HG), which inhibits a-KG-dependent histone/DNA demethylases and induces epigenetic alterations that drive tumorigenesis. The IDHm inhibitor vorasidenib extends progression-free survival in IDHm glioma patients and is expected to be widely used for this patient population. However, not all patients respond to vorasidenib, and magnetic resonance imaging (MRI) does not assess whether a patient is responding to vorasidenib. Therefore, the goal of this study was to identify metabolic alterations induced by D-2HG that can be leveraged for non-invasive imaging of IDHm gliomas. Using clinically relevant patient-derived models (BT257, BT142, BT54, SF10417, SF10602), we show that D-2HG downregulates the activity of pyruvate dehydrogenase (PDH), the rate-limiting enzyme for oxidation of glucose-derived pyruvate via the tricarboxylic acid cycle, by multiple mechanisms. Drug affinity target stability assays show that D-2HG directly binds to and inhibits PDH activity. D-2HG also inhibits a-KG-dependent prolyl hydroxylases that target hypoxia-inducible factor 1-a (HIF-1a) for degradation. As a result, D-2HG stabilizes HIF-1a and drives expression of pyruvate dehydrogenase kinase 3, which phosphorylates and inhibits PDH activity. Suppressing D-2HG using vorasidenib upregulates PDH activity in IDHm glioma cells and intracranial tumors. Next, we examined whether hyperpolarized 13C-MRS, which is an advanced MRI-based method of imaging metabolic activity, monitors PDH activity in IDHm gliomas. Following administration of hyperpolarized [2-13C]-pyruvate, metabolic conversion to [5-13C]-glutamate provides a readout of PDH activity. Our studies indicate that [5-13C]-glutamate production from hyperpolarized [2-13C]-pyruvate is upregulated in IDHm glioma cells treated with vorasidenib. Importantly, [5-13C]-glutamate production is elevated within 5 days of treatment with vorasidenib in rats bearing intracranial BT257 or BT142 xenografts, when changes cannot be observed by MRI. Collectively, our studies identify hyperpolarized [2-13C]-pyruvate as a unique probe of D-2HG-induced metabolic rewiring and highlight its ability to assess IDHm glioma response to therapy, which is a challenge in the clinic.

Clinical characteristics of patients with P4HTM variant-associated epilepsy and therapeutic exploration: a case report and literature review

The P4HTM gene encodes a transmembrane prolyl 4-hydroxylase, which is responsible for the degradation of hypoxia-inducible transcription factors (HIF) under normoxia. Clinically, biallelic P4HTM variants have been identified in patients with hypotonia, hypoventilation, intellectual disabilities, dysautonomia, epilepsy, and eye abnormalities (HIDEA syndrome). Seizure was one of the most prominent symptoms. However, the clinical features of patients with epilepsy associated with P4HTM variants remain unclear. In this report, we describe a one-month-old infant with HIDEA syndrome caused by compound heterozygous P4HTM variants (c.300dupG/p.Gly103Argfs*22 and c.488C > T/p.Ala163Val). The infant presented with clonic seizures of focal onset that responded well to valproate, but with profound intellectual disability and global developmental delay at the last follow-up at 3 years old. A review of the existing literature indicates that seizures in this population typically begin early in infancy, manifest in multiple types, and are relatively well controlled. Epilepsy seemed unrelated to developmental outcomes or disease progression. Valproate, which has HIF-1α inhibiting properties, may be a promising treatment avenue for this population.

FNDC4 alleviates cardiac ischemia/reperfusion injury through facilitating HIF1α-dependent cardiomyocyte survival and angiogenesis in male mice

Fibronectin type III domain-containing (FNDC) proteins play critical roles in cellular homeostasis and cardiac injury, and our recent findings define FNDC5 as a promising cardioprotectant against doxorubicin- and aging-related cardiac injury. FNDC4 displays a high homology with FNDC5; however, its role and mechanism in cardiac ischemia/reperfusion (I/R) injury remain elusive. Here, we show that cardiac and plasma FNDC4 levels are elevated during I/R injury in a hypoxia-inducible factor 1α (HIF1α)-dependent manner. Cardiac-specific FNDC4 overexpression facilitates, while cardiac-specific FNDC4 knockdown inhibits cardiomyocyte survival and angiogenesis in I/R-stressed hearts of male mice through regulating the proteasomal degradation of HIF1α. Interestingly, FNDC4 does not directly stimulate angiogenesis of endothelial cells, but increases the expression and secretion of fibroblast growth factor 1 from cardiomyocytes to enhance angiogenesis in a paracrine manner. Moreover, therapeutic administration of recombinant FNDC4 protein is sufficient to alleviate cardiac I/R injury in male mice, without resulting in significant side effects. In this work, we reveal that FNDC4 alleviates cardiac I/R injury through facilitating HIF1α-dependent cardiomyocyte survival and angiogenesis, and define FNDC4 as a promising predictive and therapeutic target of cardiac I/R injury.

Roxadustat Efficacy and Safety in Patients Receiving Peritoneal Dialysis: Pooled Analysis of Four Phase 3 Studies

Background/Objectives: Roxadustat is an oral hypoxia-inducible factor prolyl hydroxylase inhibitor approved to treat anemia of chronic kidney disease (CKD). The efficacy and safety of roxadustat compared with parenteral erythropoiesis-stimulating agents (ESAs) were evaluated in patients with anemia of CKD receiving peritoneal dialysis (PD). Methods: This analysis pooled data from four phase 3, multicenter, randomized, open-label, active-comparator studies (PYRENEES, SIERRAS, HIMALAYAS, ROCKIES). The primary endpoints evaluated were hemoglobin change from baseline (CFB) to Weeks 28–36 without rescue therapy and hemoglobin CFB to Weeks 28–52 regardless of rescue therapy use. Safety data were reported. Results: This analysis included 422 patients (215 roxadustat, 207 ESA). Hemoglobin CFB to Weeks 28–36 without rescue therapy and hemoglobin CFB to Weeks 28–52 regardless of rescue therapy achieved non-inferiority for roxadustat vs. ESAs. The mean weekly dose of roxadustat was maintained over time (Weeks 1–4, 3.86 mg/kg/week; Weeks 101–104, 3.27 mg/kg/week), whereas the mean weekly ESA dose increased by 24% (Weeks 1–4, 115.70 IU/kg/week; Weeks 101–104, 143.40 IU/kg/week). Fewer patients treated with roxadustat received intravenous iron supplementation and rescue therapy, and patients treated with an ESA required blood transfusions sooner. Roxadustat-treated patients experienced a greater decrease in low-density lipoprotein cholesterol levels relative to baseline vs. ESA-treated patients. Treatment-emergent adverse events were similar in both treatment groups. Major adverse cardiovascular event (MACE), MACE plus unstable angina or congestive heart failure, and all-cause mortality hazard ratios were <1; the lower limit of the 95% CIs was <0.6, and the upper limit was >1.3. Conclusions: Roxadustat was non-inferior to ESAs in correcting and maintaining hemoglobin levels, with stable dosing and a comparable safety profile, in anemic patients receiving PD.