Search Results (13)

The VHL–HIF-1α–VEGF axis regulates angiogenesis and metabolism. Beyond oncology, pVHL is essential for pancreatic β-cell function and is reduced in hypercaloric diet (HCD)-induced type 2 diabetes mellitus (T2DM). This study aimed to overexpress pVHL in pancreatic tissue and evaluate its effects on blood glucose levels and the expression of proteins related to glucose metabolism in the pancreas. HCD-induced diabetic C57BL/6 and BALB/c mice received a single intrapancreatic injection of an adenoviral vector (1 × 10¹² viral particles) encoding the murine Vhlh gene (AdVHL) to induce transient pVHL overexpression. The glycemic delta (post-load glucose minus fasting) and net incremental area under the curve (niAUC) were determined on days 3, 6, 9, 12, and 15 post-treatment, as the peak in GFP overexpression (used as a surrogate reporter of transduction efficiency) was detected between days 9 and 12. Immunohistochemistry (IHC) and immunofluorescence (IF) were used to assess the expression of pVHL, HIF-1α, GLUT-1, GLUT-2, and insulin in pancreatic tissue. AdVHL treatment significantly decreased the glycemic delta and niAUC in mice with T2DM (p < 0.01). On day 15 after treatment, HIF-1α and GLUT-1 expression were markedly reduced in AdVHL-treated mice (p < 0.01), while GLUT-2 and insulin were significantly increased (p < 0.01). These results were reproduced in both mouse strains. Transient overexpression of pVHL in pancreatic tissue of mice with T2DM was associated with decreased glucose levels and changes in the expression of proteins related to glucose metabolism in the pancreas, resembling a healthier phenotype than that of mice with T2DM. These findings support an important functional role of the pVHL–HIF-1α axis in pancreatic physiology, provide a proof-of-concept for further mechanistic and translational studies, and implicate pVHL in the altered glucose metabolism observed in T2DM. Full article

Clear cell renal cell carcinoma (ccRCC) is driven by von Hippel-Lindau (VHL) tumor suppressor loss and persistent activation of hypoxia-inducible factors (HIFs), which coordinately regulate angiogenesis, metabolic reprogramming, redox balance, and tumor–immune interactions. Although immune checkpoint inhibitors and vascular endothelial growth factor-targeted therapies have improved outcomes, resistance remains common due to adaptive network plasticity. Selected natural products have been reported to exhibit multitarget regulatory activities that may influence interconnected oncogenic pathways. This review highlights how compounds such as curcumin, resveratrol, quercetin, and epigallocatechin-3-gallate modulate the VHL-HIF axis, disrupt metabolic and redox homeostasis, and influence tumor–immune system interactions in ccRCC. We propose a system-level framework in which natural products enhance therapeutic sensitivity; however, further validation is required for clinical translation. Full article

Clear-cell renal cell carcinoma (ccRCC) is characterised by constitutive activation of hypoxia-inducible factors (HIFs) following VHL loss, which contributes to tumour progression and therapeutic resistance. Given the limitations of VEGFR-targeted therapies, we investigated the biological and potential therapeutic relevance of the HIF axis in ccRCC. Nuclear and cytoplasmic HIF1A and EPAS1/HIF2A expression were assessed by immunohistochemistry in tumours from 40 patients and correlated with clinicopathological parameters and cancer-specific survival. The functional effects of HIF pathway inhibitors (GN44028, KC7F2, and FM19G11) and sunitinib were analysed in VHL-mutant 786-O and VHL-wild-type Caki-1 cell lines using SRB viability assay, cell cycle analysis, wound closure assay, and RT-qPCR of HIF-related genes, with comparison to non-malignant HK-2 cells. TCGA-ccRCC data from advanced-stage patients (III–IV, n = 185) were analysed as a complementary transcriptomic context. Nuclear, but not cytoplasmic, HIF1A and EPAS1/HIF2A expression was associated with advanced stage and shorter survival in univariable analyses. GN44028 showed the most pronounced antiproliferative effect under tested conditions and was associated with broad suppression of HIF-related transcription, whereas sunitinib was associated with increased expression of selected HIF-related genes. GN44028 did not demonstrate clear selectivity over non-malignant HK-2 cells. Overall, nuclear HIF activation is associated with aggressive ccRCC biology, and broader HIF pathway modulation warrants further experimental investigation; however, the clinical findings remain exploratory, and therapeutic selectivity and translational relevance are not yet established. Full article

(1) Background: The naked mole-rat (Heterocephalus glaber) survives hypoxia–reoxygenation stresses by utilizing metabolic rate depression, achieved in part by downregulating nonessential genes and processes to conserve endogenous cellular resources and prevent buildup of toxic waste byproducts. Tight molecular control of protein degradation (specifically the ubiquitin–proteasome system) is a potent regulatory tool for maintaining muscle integrity during hypoxia, but how this system is regulated in the heart of hypoxia-tolerant species is poorly understood. (2) Methods: The protein expression levels of cullin-RING E3 ligases (specifically CRL4 architecture), deubiquitinating enzymes, and proteasomal activity were assayed in cardiac tissues from H. glaber exposed to 24 h of normoxia or hypoxia in vivo. (3) Results: Overall, the protein expression of E3 ligases decreased, whereas expression of deubiquitinating enzymes increased during hypoxia, all of which play roles in themes of oxidative stress, heightened DNA damage repair, and the HIF-1-VHL-NFκB axis. Proteasomal activity was elevated during hypoxia, which conceivably links to the oxidative stress theory of aging and longevity of H. glaber. (4) Conclusions: Taken together, our results expand current research into protein degradation and extreme environmental stress responses, with a specific focus on cardiac mechanisms related to oxidative stress resistance along the hypoxia-longevity axis. Full article

Glioblastoma (GBM) is the most aggressive and lethal primary brain tumor, characterized by rapid proliferation, extensive vascularization, and resistance to conventional therapies. A feature of the GBM microenvironment is hypoxia, which activates a wide range of adaptive responses orchestrated mainly by the hypoxia-inducible factor (HIF). The Von Hippel–Lindau protein (pVHL) is a central regulator of HIF stability, inducing proteasomal degradation under physiological conditions. However, in GBM, the pVHL is frequently mutated or functionally inactivated by several mechanisms, including microRNA regulation, post-translational modifications, or degradation by specific E3 ubiquitin ligases. This loss of function results in persistent HIF activation, thereby enhancing the oncogenic and pro-angiogenic environment that contributes to the progression and aggressiveness of GBM. This review focuses on the multifaceted roles of the pVHL-HIF axis and proposes it as a key driver of GBM malignancy. Full article

Background: Hypoxia-induced glycolysis represents a hallmark of colorectal cancer (CRC) progression and contributes significantly to therapeutic resistance. Curcumol, a natural sesquiterpenoid derived from Curcumae Rhizoma, has demonstrated promising anti-tumor properties. However, its impact on metabolic reprogramming under hypoxic conditions remains largely undefined. Objective: The objective of this study was to elucidate the potential of Curcumol in inhibiting glycolytic reprogramming and impede CRC progression via regulation of the VHL/HIF-1α signaling pathway. Methods: CRC cells and orthotopic mouse models were treated with Curcumol under chemically induced hypoxic conditions. Metabolic alterations were evaluated using Seahorse extracellular flux analysis, Western blot analysis, quantitative real-time PCR (qRT-PCR), immunohistochemistry (IHC) and co-immunoprecipitation (Co-IP). Functional validation of glycolysis and epithelial–mesenchymal transition (EMT) phenotypes was conducted through in vitro and in vivo assays. Results: Curcumol inhibited HIF-1α-mediated metabolic reprogramming by upregulating VHL expression, thereby promoting HIF-1α degradation. This effect led to the downregulation of key glycolytic genes (HK2, LDHA, and GLUT1), decreased glycolytic flux, and lactate production, ultimately suppressing CRC cell proliferation and invasion. The anti-tumor efficacy of Curcumol was validated in both in vitro and in vivo models. Moreover, Curcumol effectively reversed the hypoxia-induced epithelial–mesenchymal transition (EMT) phenotype, suggesting that its metabolic regulatory effects may contribute to reduced metastatic potential. Conclusions: Curcumol suppresses glycolysis and CRC progression by activating the VHL/HIF-1α signaling axis. These findings underscore the potential of Curcumol as a natural metabolic regulator capable of reversing tumor metabolic reprogramming, offering a promising therapeutic strategy for CRC treatment. Full article

Mutations of the von Hippel–Lindau (VHL) tumor suppressor gene occur frequently in clear cell renal cell carcinoma (RCC), the predominant histology of kidney cancer, and have been associated with its pathogenesis and progression. Alterations of VHL lead to impaired degradation of hypoxia-inducible factor 1α (HIF1α) and HIF2α promoting neoangiogenesis, which is pivotal for cancer growth. As such, targeting the VHL-HIF axis holds relevant potential for therapeutic purposes. Belzutifan, an HIF-2α inhibitor, has been recently indicated for metastatic RCC and other antiangiogenic drugs directed against HIF-2α are currently under investigation. Further, clinical and preclinical studies of combination approaches for metastatic RCC including belzutifan with cyclin-dependent kinase 4–6 inhibitors, tyrosine kinase inhibitors, or immune checkpoint inhibitors achieved promising results or are ongoing. This review aims to summarize the existing evidence regarding the VHL/HIF pathway, and the approved and emerging treatment strategies that target this pivotal molecular axis and their mechanisms of resistance. Full article

Human papillomavirus 16 (HPV 16) infection is associated with several types of cancer, such as head and neck, cervical, anal, and penile cancer. Its oncogenic potential is due to the ability of the E6 and E7 oncoproteins to promote alterations associated with cell transformation. HPV 16 E6 and E7 oncoproteins increase metabolic reprogramming, one of the hallmarks of cancer, by increasing the stability of hypoxia-induced factor 1 α (HIF-1α) and consequently increasing the expression levels of their target genes. In this report, by bioinformatic analysis, we show the possible effect of HPV 16 oncoproteins E6 and E7 on metabolic reprogramming in cancer through the E6-E7-PHD2-VHL-CUL2-ELOC-HIF-1α axis. We proposed that E6 and E7 interact with VHL, CUL2, and ELOC in forming the E3 ubiquitin ligase complex that ubiquitinates HIF-1α for degradation via the proteasome. Based on the information found in the databases, it is proposed that E6 interacts with VHL by blocking its interaction with HIF-1α. On the other hand, E7 interacts with CUL2 and ELOC, preventing their binding to VHL and RBX1, respectively. Consequently, HIF-1α is stabilized and binds with HIF-1β to form the active HIF1 complex that binds to hypoxia response elements (HREs), allowing the expression of genes related to energy metabolism. In addition, we suggest an effect of E6 and E7 at the level of PHD2, VHL, CUL2, and ELOC gene expression. Here, we propose some miRNAs targeting PHD2, VHL, CUL2, and ELOC mRNAs. The effect of E6 and E7 may be the non-hydroxylation and non-ubiquitination of HIF-1α, which may regulate metabolic processes involved in metabolic reprogramming in cancer upon stabilization, non-degradation, and translocation to the nucleus. Full article

Renal cell carcinoma (RCC) represents 85–95% of kidney cancers and is the most frequent type of renal cancer in adult patients. It accounts for 3% of all cancer cases and is in 7th place among the most frequent histological types of cancer. Clear cell renal cell carcinoma (ccRCC), accounts for 75% of RCCs and has the most kidney cancer-related deaths. One-third of the patients with ccRCC develop metastases. Renal cancer presents cellular alterations in sugars, lipids, amino acids, and nucleic acid metabolism. RCC is characterized by several metabolic dysregulations including oxygen sensing (VHL/HIF pathway), glucose transporters (GLUT 1 and GLUT 4) energy sensing, and energy nutrient sensing cascade. Metabolic reprogramming represents an important characteristic of the cancer cells to survive in nutrient and oxygen-deprived environments, to proliferate and metastasize in different body sites. The phosphoinositide 3-kinase-AKT-mammalian target of the rapamycin (PI3K/AKT/mTOR) signaling pathway is usually dysregulated in various cancer types including renal cancer. This molecular pathway is frequently correlated with tumor growth and survival. The main aim of this review is to present renal cancer types, dysregulation of PI3K/AKT/mTOR signaling pathway members, crosstalk with VHL/HIF axis, and carbohydrates, lipids, and amino acid alterations. Full article

The clear cell variant of renal cell carcinoma (ccRCC) is the most common renal epithelial malignancy and responsible for most of the deaths from kidney cancer. Patients carrying inactivating mutations in the Von Hippel-Lindau (VHL) gene have an increased proclivity to develop several types of tumors including ccRCC. Normally, the Hypoxia Inducible Factor alpha (HIF-α) subunits of the HIF heterodimeric transcription factor complex are regulated by oxygen-dependent prolyl-hydroxylation, VHL-mediated ubiquitination and proteasomal degradation. Loss of pVHL function results in elevated levels of HIF-α due to increased stability, leading to RCC progression. While HIF-1α acts as a tumor suppressor, HIF-2α promotes oncogenic potential by driving tumor progression and metastasis through activation of hypoxia-sensitive signaling pathways and overexpression of HIF-2α target genes. One strategy to suppress ccRCC aggressiveness is directed at inhibition of HIF-2α and the associated molecular pathways leading to cell proliferation, angiogenesis, and metastasis. Indeed, clinical and pre-clinical data demonstrated the effectiveness of HIF-2α targeted therapy in attenuating ccRCC progression. This review focuses on the signaling pathways and the involved genes (cyclin D, c-Myc, VEGF-a, EGFR, TGF-α, GLUT-1) that confer oncogenic potential downstream of the VHL-HIF-2α signaling axis in ccRCC. Discussed as well are current treatment options (including receptor tyrosine kinase inhibitors such as sunitinib), the medical challenges (high prevalence of metastasis at the time of diagnosis, refractory nature of advanced disease to current treatment options), scientific challenges and future directions. Full article

Von Hippel-Lindau (VHL) disease is an autosomal dominant condition that predisposes affected individuals to a variety of malignant and benign neoplasms. The pathogenetic turning point of this illness is the accumulation of hypoxia-inducible factor (HIF)-1α, a transcription factor of several genes involved in oncogenesis, angiogenesis, tissue regeneration, metabolic regulation, hematopoiesis, and inflammatory responses. From an oncological perspective, increased awareness of the molecular pathways underlying this disease is bringing us closer to the development of specific and targeted therapies. Meanwhile, on the surgical side, improved understanding can help to better identify the patients to be treated and the surgical timing. Overall, pathogenesis research is crucial for developing patient-tailored therapies. One of the actual key topics of interest is the link between the VHL/HIF axis and inflammation. The present study aims to outline the fundamental mechanisms that link VHL disease and immune disorders, as well as to explore the details of the overlap between VHL disease and myasthenia gravis (MG) pathogenetic pathways. As a result, MG becomes a paradigm for autoimmune disorders that might be related with VHL disease. Full article

Von Hippel-Lindau disease (VHL disease or VHL syndrome) is a familial multisystem neoplastic syndrome stemming from germline disease-associated variants of the VHL tumor suppressor gene on chromosome 3. VHL is involved, through the EPO-VHL-HIF signaling axis, in oxygen sensing and adaptive response to hypoxia, as well as in numerous HIF-independent pathways. The diverse roles of VHL confirm its implication in several crucial cellular processes. VHL variations have been associated with the development of VHL disease and erythrocytosis. The association between genotypes and phenotypes still remains ambiguous for the majority of mutations. It appears that there is a distinction between erythrocytosis-causing VHL variations and VHL variations causing VHL disease with tumor development. Understanding the pathogenic effects of VHL variants might better predict the prognosis and optimize management of the patient. Full article

Approximately 400,000 patients are diagnosed with kidney cancer annually worldwide, leading to approximately 170,000 deaths. Renal cell carcinoma (RCC) accounts for more than 90% of kidney cancers. The most common histological subtype is clear cell RCC, which is found in approximately 85% of metastatic RCC cases. The VHL-HIF-VEGF axis is well known; therefore, targeting VEGF has been the mainstay for managing advanced clear cell RCC. Recently, the treatment landscape for advanced clear cell RCC has changed extensively. In particular, immune checkpoint inhibitor-based treatment showed promising results in front-line treatment and became the standard of care. Herein, we review the current evidence on front-line treatment options and discuss the clinical and future perspective. Full article