Genetic and functional studies implicate HIF1α as a 14q kidney cancer suppressor gene

Manganese-Doped Nanoparticles with Hypoxia-Inducible Factor 2α Inhibitor That Elicit Innate Immune Responses against von Hippel-Lindau Protein-Deficient Tumors

The von Hippel-Lindau (VHL) tumor suppressor gene product, pVHL, is frequently deficient in a variety of human cancers. In addressing the treatment of pVHL-deficient tumors, hypoxia-inducible factor 2α (HIF-2α) has risen as a promising therapeutic target, culminating in the development of specific inhibitors like PT2385 and its analogues. Nonetheless, the absence of targeted delivery capabilities in these inhibitors heightens the risk of on-target toxicities. To mitigate these limitations, we have engineered a nanoparticle, termed PMMF (PT/MMSN@DSPE-PEG-FA), capable of delivering both a HIF-2α antagonist (PT2385) and manganese directly to tumor sites. PMMF has shown effective targeting of pVHL-deficient clear-cell renal cell carcinoma and melanoma, leading to significant therapeutic benefits and alleviating hypoxic and immunosuppressive traits of the tumor microenvironment. Functionally, PMMF boosts the cyclic GMP-AMP synthase-stimulator of interferon genes signaling pathway, which, in turn, stimulates a robust innate immune response. This response activates natural killer (NK) cells and CD8+ T lymphocytes while curbing the infiltration of regulatory T cells. Notably, the therapeutic efficacy of PMMF is markedly reduced when NK cells are blocked but not affected by neutrophil blockade, highlighting the critical role of NK cells in PMMF-induced antitumor immunity. Additionally, the safety profile of PMMF showed minimal systemic post-treatment cytotoxicity. In summary, our findings position PMMF as a promising platform for treating tumors with pVHL deficiency and underscore the therapeutic potential of metalloimmunotherapy.

HIF regulates multiple translated endogenous retroviruses: Implications for cancer immunotherapy

Clear cell renal cell carcinoma (ccRCC), despite having a low mutational burden, is considered immunogenic because it occasionally undergoes spontaneous regressions and often responds to immunotherapies. The signature lesion in ccRCC is inactivation of the VHL tumor suppressor gene and consequent upregulation of the HIF transcription factor. An earlier case report described a ccRCC patient who was cured by an allogeneic stem cell transplant and later found to have donor-derived T cells that recognized a ccRCC-specific peptide encoded by a HIF-responsive endogenous retrovirus (ERV), ERVE-4. We report that ERVE-4 is one of many ERVs that are induced by HIF, translated into HLA-bound peptides in ccRCCs, and capable of generating antigen-specific T cell responses. Moreover, ERV expression can be induced in non-ccRCC tumors with clinical-grade HIF stabilizers. These findings have implications for leveraging ERVs for cancer immunotherapy.

Oncogenic TFE3 fusions drive OXPHOS and confer metabolic vulnerabilities in translocation renal cell carcinoma

Translocation renal cell carcinoma (tRCC) is an aggressive subtype of kidney cancer driven by TFE3 gene fusions, which act via poorly characterized downstream mechanisms. Here we report that TFE3 fusions transcriptionally rewire tRCCs toward oxidative phosphorylation (OXPHOS), contrasting with the highly glycolytic nature of most other renal cancers. Reliance on this TFE3 fusion-driven OXPHOS programme renders tRCCs vulnerable to NADH reductive stress, a metabolic stress induced by an imbalance of reducing equivalents. Genome-scale CRISPR screening identifies tRCC-selective vulnerabilities linked to this metabolic state, including EGLN1, which hydroxylates HIF-1α and targets it for proteolysis. Inhibition of EGLN1 compromises tRCC cell growth by stabilizing HIF-1α and promoting metabolic reprogramming away from OXPHOS, thus representing a vulnerability for OXPHOS-dependent tRCC cells. Our study defines tRCC as being dependent on a mitochondria-centred metabolic programme driven by TFE3 fusions and nominates EGLN1 inhibition as a therapeutic strategy in this cancer.

Copper Drives Remodeling of Metabolic State and Progression of Clear Cell Renal Cell Carcinoma

SIGNIFICANCE

The work establishes a requirement for glucose-dependent coordination between energy production and redox homeostasis, which is fundamental for the survival of cancer cells that accumulate Cu and contributes to tumor growth.

Hypoxia-inducible transcription factors: architects of tumorigenesis and targets for anticancer drug discovery

Hypoxia-inducible factors (HIFs) play a pivotal role as master regulators of tumor survival and growth, controlling a wide array of cellular processes in response to hypoxic stress. Clinical data correlates upregulated HIF-1 and HIF-2 levels with an aggressive tumor phenotype and poor patient outcome. Despite extensive validation as a target in cancer, pharmaceutical targeting of HIFs, particularly the interaction between α and βsubunits that forms the active transcription factor, has proved challenging. Nonetheless, many indirect inhibitors of HIFs have been identified, targeting diverse parts of this pathway. Significant strides have also been made in the development of direct inhibitors of HIF-2, exemplified by the FDA approval of Belzutifan for the treatment of metastatic clear cell renal carcinoma. While efforts to target HIF-1 using various therapeutic modalities have shown promise, no clinical candidates have yet emerged. This review aims to provide insights into the intricate and extensive role played by HIFs in cancer, and the ongoing efforts to develop therapeutic agents against this target.

Conserved patterns of transcriptional dysregulation, heterogeneity, and cell states in clear cell kidney cancer

Clear cell kidney cancers are characterized both by conserved oncogenic driver events and by marked intratumor genetic and phenotypic heterogeneity, which help drive tumor progression, metastasis, and resistance to therapy. How these are reflected in transcriptional programs within the cancer and stromal cell components remains an important question with the potential to drive novel therapeutic approaches to treating cancer. To better understand these programs, we perform single-cell transcriptomics on 75 multi-regional biopsies from kidney tumors and normal kidney. We identify conserved patterns of transcriptional dysregulation and their upstream regulators within the tumor and associated vasculature. We describe recurrent subclonal transcriptional consequences of Chr14q loss linked to metastatic potential. We identify prognostically significant conserved patterns of intratumor transcriptional heterogeneity. These reflect co-existing cell states found in both cancer cells and normal kidney cells, indicating that rather than arising from genetic heterogeneity they are a consequence of lineage plasticity.

HIF2α inhibits glutaminase clustering in mitochondria to sustain growth of clear cell Renal Cell Carcinoma

Clear cell renal cell carcinomas (ccRCC) are largely driven by HIF2α and are avid consumers of glutamine. However, inhibitors of glutaminase1 (GLS1), the first step in glutaminolysis, have not shown benefit in phase III trials, and HIF2α inhibition, recently FDA-approved for treatment of ccRCC, shows great but incomplete benefits, underscoring the need to better understand the roles of glutamine and HIF2α in ccRCC. Here, we report that glutamine deprivation rapidly redistributes GLS1 into isolated clusters within mitochondria across diverse cell types, but not in ccRCC. GLS1 clustering is rapid (1-3 hours) and reversible, is specifically driven by reduced intracellular glutamate, and is mediated by mitochondrial fission. Clustered GLS1 markedly enhances glutaminase activity and promotes cell death under glutamine-deprived conditions. HIF2α prevents GLS1 clustering, independently of its transcriptional activity, thereby protecting ccRCC cells from cell death induced by glutamine deprivation. Reversing this protection, by genetic expression of GLS1 mutants that constitutively cluster, enhances ccRCC cell death in culture and suppresses ccRCC growth in vivo. These findings provide multiple insights into cellular glutamine handling, including a novel metabolic pathway by which HIF2α promotes ccRCC, and reveals a potential therapeutic avenue to synergize with HIF2α inhibition in the treatment of ccRCC.

Systematic and comprehensive insights into HIF-1 stabilization under normoxic conditions: implications for cellular adaptation and therapeutic strategies in cancer

Hypoxia-inducible factors (HIFs) are essential transcription factors that orchestrate cellular responses to oxygen deprivation. HIF-1α, as an unstable subunit of HIF-1, is usually hydroxylated by prolyl hydroxylase domain enzymes under normoxic conditions, leading to ubiquitination and proteasomal degradation, thereby keeping low levels. Instead of hypoxia, sometimes even in normoxia, HIF-1α translocates into the nucleus, dimerizes with HIF-1β to generate HIF-1, and then activates genes involved in adaptive responses such as angiogenesis, metabolic reprogramming, and cellular survival, which presents new challenges and insights into its role in cellular processes. Thus, the review delves into the mechanisms by which HIF-1 maintains its stability under normoxia including but not limited to giving insights into transcriptional, translational, as well as posttranslational regulation to underscore the pivotal role of HIF-1 in cellular adaptation and malignancy. Moreover, HIF-1 is extensively involved in cancer and cardiovascular diseases and potentially serves as a bridge between them. An overview of HIF-1-related drugs that are approved or in clinical trials is summarized, highlighting their potential capacity for targeting HIF-1 in cancer and cardiovascular toxicity related to cancer treatment. The review provides a comprehensive insight into HIF-1's regulatory mechanism and paves the way for future research and therapeutic development.

Targeting HIF-2α: the role of belzutifan in clear cell renal carcinoma management

INTRODUCTION

Belzutifan is a first-in-class hypoxia-inducible factor-2 alpha (HIF-2α) inhibitor. It targets the von Hippel-Lindau protein (pVHL)-HIF-vascular endothelial growth factor (VEGF) pathway, which is crucial in cellular responses to hypoxia. By inhibiting HIF-2α, belzutifan disrupts the transcription of genes involved in tumor growth and angiogenesis.

AREAS COVERED

In this review, we describe the pVHL-HIF-VEGF pathway and how it led to the development of HIF inhibitors, including belzutifan. A search was conducted for trials involving Belzutifan, including phase I-III trials. We describe the relevant toxicity, with emphasis on hypoxia and anemia.

EXPERT OPINION

Belzutifan is a relatively safe drug, with manageable adverse events, including anemia and hypoxia as on-target toxicity. Ongoing trials are studying its benefit in overall survival for RCC in first-line treatment and its potential in other malignancies. The LITESPARK-005 trial reported the benefit of belzutifan in progression-free survival (PFS) compared to everolimus in later lines of treatment, with improvement in quality-of-life outcomes. Given its different mechanism of action to currently available treatments, belzutifan is expected to play a prominent role in the treatment of clear cell renal carcinoma and other cancers.

Hypoxia-Inducible Factor in Renal Cell Carcinoma: From Molecular Insights to Targeted Therapies

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.

Dysregulation of ubiquitination modification in renal cell carcinoma

Renal cell carcinoma (RCC) is a malignant tumor of the renal tubular epithelial cells with a relatively high incidence rate worldwide. A large number of studies have indicated that dysregulation of the ubiquitination, including ubiquitination and dysregulation, is associated with the occurrence and development of RCC. This review focuses on several abnormal signaling pathways caused by E3 ligases and deubiquitinases. Additionally, we discuss research progress in RCC treatment by targeting key enzymes related to ubiquitination modifications.

Novel serous effusion-related risk models and biomarkers for predicting prognosis in T-cell lymphoma patients

T-cell lymphomas (TCLs) are a cluster of lymphoproliferative diseases with high heterogeneity, which lack accurate prognostic models and standard treatment regimen at present. Serous effusion (SE) is a relatively common manifestation and poses more challenges for risk stratification in TCLs. In this study, entire of 518 newly diagnosed TCLs patients were included. SE was found to be tightly correlated to clinical characteristics and prognosis in TCL patients, and SE volume (SEV) > 1000 ml was identified as a potential prognostic factor. Novel AEBS risk model, including age > 60, ECOG PS > 1, β2-microglobulin (BMG) > 3.0 mg/L and SEV > 1000 ml, which exerted superior efficacy for risk stratification compared to the current risk systems in TCL patients with SE. Besides, multiple RNA-seq datasets were used for the identification and function analysis of SE-related genes (SERGs). TCL patients in different SERGs-associated subgroups exhibited discrepancy in the infiltration of immunocytes and the expression of immune checkpoints. SERGs signature, including HIF1A, FERMT2, NFATC1 and COL1A1, was established and demonstrated to have distinguishing capacity for predicting prognosis in TCL patients. Moreover, immunohistochemistry revealed that SE-related molecule HIF1A was reductively expressed and related to inferior prognosis in TCL patients, especially in SE group. Pan-cancer analysis found HIF1A expression was decreased in several tumors, and chemosensitivity analysis revealed that HIF1A was associated with sensitivity of several anti-tumor drugs, such as Sorafenib, Navitoclax, and Venetoclax. Our findings provide evidence for identifying high-risk population and facilitating individualized treatment in TCL patients with SE.

Von Hippel-Lindau protein signalling in clear cell renal cell carcinoma

The distinct pathological and molecular features of kidney cancer in adaptation to oxygen homeostasis render this malignancy an attractive model for investigating hypoxia signalling and potentially developing potent targeted therapies. Hypoxia signalling has a pivotal role in kidney cancer, particularly within the most prevalent subtype, known as renal cell carcinoma (RCC). Hypoxia promotes various crucial pathological processes, such as hypoxia-inducible factor (HIF) activation, angiogenesis, proliferation, metabolic reprogramming and drug resistance, all of which contribute to kidney cancer development, growth or metastasis formation. A substantial portion of kidney cancers, in particular clear cell RCC (ccRCC), are characterized by a loss of function of Von Hippel-Lindau tumour suppressor (VHL), leading to the accumulation of HIF proteins, especially HIF2α, a crucial driver of ccRCC. Thus, therapeutic strategies targeting pVHL-HIF signalling have been explored in ccRCC, culminating in the successful development of HIF2α-specific antagonists such as belzutifan (PT2977), an FDA-approved drug to treat VHL-associated diseases including advanced-stage ccRCC. An increased understanding of hypoxia signalling in kidney cancer came from the discovery of novel VHL protein (pVHL) targets, and mechanisms of synthetic lethality with VHL mutations. These breakthroughs can pave the way for the development of innovative and potent combination therapies in kidney cancer.

Research progress on the correlation between obesity and the occurrence and development of kidney cancer: a narrative review

Background and Objective

Obesity is an important risk factor for the onset of kidney cancer, and the mechanism of obesity leading to the occurrence and development of kidney cancer has been further studied and confirmed in the past decade. The emergence of the "obesity paradox" phenomenon has made the correlation between obesity and the prognosis of kidney cancer survival controversial. This review summarizes the association between obesity and the occurrence and development of kidney cancer based on newly discovered evidence in the past 10 years, in order to provide reference for follow-up research.

Methods

A comprehensive, non-systematic review of the latest literature was carried out in order to investigate the progress of the correlation between obesity and kidney cancer. PubMed, Web of Science and Embase were being examined and the last run was on July 15, 2024.

Key Content and Findings

The correlation between obesity and the occurrence and development of kidney cancer was discussed in this review, and the newly discovered evidence of epidemiology and related mechanisms in the past 10 years was summarized. The latest evidence suggests that obesity is an important risk factor for the development of kidney cancer. Perirenal fat plays an important role in promoting kidney cancer progression and prognosis.

Conclusions

Epidemiology shows that the high rates of kidney cancer and obesity coincide in terms of region and ethnicity. The underlying mechanisms associated with obesity in promoting the occurrence and development of kidney cancer mainly include: abnormal expression of adipocytokines, abnormal lipid metabolism, abnormalities in the insulin-like growth factor-I (IGF-I) axis and hyperinsulinemia/insulin resistance, hypoxia and inflammation. As adipose tissue is adjacent to the kidney, the effect of perirenal adipose tissue on the prognosis of kidney cancer is controversial, and some evidence supports the idea of the "obesity paradox".

Toward a CRISPR-based mouse model of Vhl-deficient clear cell kidney cancer: Initial experience and lessons learned

CRISPR is revolutionizing the ability to do somatic gene editing in mice for the purpose of creating new cancer models. Inactivation of the VHL tumor suppressor gene is the signature initiating event in the most common form of kidney cancer, clear cell renal cell carcinoma (ccRCC). Such tumors are usually driven by the excessive HIF2 activity that arises when the VHL gene product, pVHL, is defective. Given the pressing need for a robust immunocompetent mouse model of human ccRCC, we directly injected adenovirus-associated viruses (AAVs) encoding sgRNAs against VHL and other known/suspected ccRCC tumor suppressor genes into the kidneys of C57BL/6 mice under conditions where Cas9 was under the control of one of two different kidney-specific promoters (Cdh16 or Pax8) to induce kidney tumors. An AAV targeting Vhl, Pbrm1, Keap1, and Tsc1 reproducibly caused macroscopic ccRCCs that partially resembled human ccRCC tumors with respect to transcriptome and cell of origin and responded to a ccRCC standard-of-care agent, axitinib. Unfortunately, these tumors, like those produced by earlier genetically engineered mouse ccRCCs, are HIF2 independent.

Network modeling links kidney developmental programs and the cancer type-specificity of VHL mutations

Elucidating the molecular dependencies behind the cancer-type specificity of driver mutations may reveal new therapeutic opportunities. We hypothesized that developmental programs would impact the transduction of oncogenic signaling activated by a driver mutation and shape its cancer-type specificity. Therefore, we designed a computational analysis framework by combining single-cell gene expression profiles during fetal organ development, latent factor discovery, and information theory-based differential network analysis to systematically identify transcription factors that selectively respond to driver mutations under the influence of organ-specific developmental programs. After applying this approach to VHL mutations, which are highly specific to clear cell renal cell carcinoma (ccRCC), we revealed important regulators downstream of VHL mutations in ccRCC and used their activities to cluster patients with ccRCC into three subtypes. This classification revealed a more significant difference in prognosis than the previous mRNA profile-based method and was validated in an independent cohort. Moreover, we found that EP300, a key epigenetic factor maintaining the regulatory network of the subtype with the worst prognosis, can be targeted by a small inhibitor, suggesting a potential treatment option for a subset of patients with ccRCC. This work demonstrated an intimate relationship between organ development and oncogenesis from the perspective of systems biology, and the method can be generalized to study the influence of other biological processes on cancer driver mutations.

SMEK1 promotes clear cell renal cell carcinoma progression via EGFR tyrosine-kinase dependent pathway

Studying the mechanisms underlying clear cell renal cell carcinoma (ccRCC), the most common subtype of kidney cancer, may address an unmet need in ccRCC-targeted drug research. Growing evidences indicate that protein phosphatase 4 (PP4) plays an important role in cancer biology. Here, we characterized the upregulation of PP4 core component SMEK1 in ccRCC using tissue microarrays and revealed that its high expression is closely associated with reduced patient survival. We then conducted cell function experiments and animal experiments to prove the tumor-promoting effect of SMEK1. Next, RNA-seq was performed to explore its underlying mechanism, and the results revealed that SMEK1-regulated genes were extensively involved in cell motility, and the canonical tyrosine kinase receptor EGFR was one of its targets. Moreover, we verified the regulatory effect of SMEK1 on EGFR and its downstream MAPK and AKT pathway through molecular experiments, in which erlotinib, a tyrosine kinase inhibitor, can partially block this regulation, demonstrating that SMEK1 mediates its effects dependent on the tyrosine kinase activity of EGFR. Mechanistically, SMEK1 bond to PRMT5 and facilitated PRMT5-mediated histone methylation to promote the transcription of EGFR. Furthermore, we studied the upstream regulators of SMEK1 and demonstrated that the transcription factor E2F1 could directly bind to the SMEK1 promoter by chromatin immunoprecipitation. Functionally, E2F1 could also induce ccRCC progression by manipulating the expression of SMEK1. Collectively, our findings demonstrate the overexpression of SMEK1 in ccRCC, and reveal a novel E2F1/SMEK1/PRMT5/EGFR-tyrosine-kinase-dependent pathway for ccRCC progression.

Differential effects of hypoxia on motility using various in vitro models of lung adenocarcinoma

Lung cancer is the leading cause of cancer-related death globally. Metastasis is the most common reason of mortality in which hypoxia is suggested to have a pivotal role. However, the effect of hypoxia on the metastatic potential and migratory activity of cancer cells is largely unexplored and warrants detailed scientific investigations. Accordingly, we analyzed changes on cell proliferation and migratory activity both in single-cell migration and invasion under normoxic and hypoxic conditions in lung adenocarcinoma cell lines. Alterations in crucial genes and proteins associated with cellular response to hypoxia, epithelial-mesenchymal transition, proliferation and apoptosis were also analyzed. Generally, we observed no change in proliferation upon hypoxic conditions and no detectable induction of apoptosis. Interestingly, we observed that single-cell motility was generally reduced while invasion under confluent conditions using scratch assay was enhanced by hypoxia in most of the cell lines. Furthermore, we detected changes in the expression of EMT markers that are consistent with enhanced motility and metastasis-promoting effect of hypoxia. In summary, our study indicated cell line-, time of exposure- and migrational type-dependent effects of hypoxia in cellular proliferation, motility and gene expression. Our results contribute to better understanding and tackling cancer metastasis.

TFE3 fusions direct an oncogenic transcriptional program that drives OXPHOS and unveils vulnerabilities in translocation renal cell carcinoma

Translocation renal cell carcinoma (tRCC) is an aggressive subtype of kidney cancer driven by TFE3 gene fusions, which act via poorly characterized downstream mechanisms. Here we report that TFE3 fusions transcriptionally rewire tRCCs toward oxidative phosphorylation (OXPHOS), contrasting with the highly glycolytic metabolism of most other renal cancers. This TFE3 fusion-driven OXPHOS program, together with heightened glutathione levels found in renal cancers, renders tRCCs sensitive to reductive stress - a metabolic stress state induced by an imbalance of reducing equivalents. Genome-scale CRISPR screening identifies tRCC-selective vulnerabilities linked to this metabolic state, including EGLN1, which hydroxylates HIF-1α and targets it for proteolysis. Inhibition of EGLN1 compromises tRCC cell growth by stabilizing HIF-1a and promoting metabolic reprogramming away from OXPHOS, thus representing a vulnerability to OXPHOS-dependent tRCC cells. Our study defines a distinctive tRCC-essential metabolic program driven by TFE3 fusions and nominates EGLN1 inhibition as a therapeutic strategy to counteract fusion-induced metabolic rewiring.

Saturation genome editing maps the functional spectrum of pathogenic VHL alleles

To maximize the impact of precision medicine approaches, it is critical to identify genetic variants underlying disease and to accurately quantify their functional effects. A gene exemplifying the challenge of variant interpretation is the von Hippel-Lindautumor suppressor (VHL). VHL encodes an E3 ubiquitin ligase that regulates the cellular response to hypoxia. Germline pathogenic variants in VHL predispose patients to tumors including clear cell renal cell carcinoma (ccRCC) and pheochromocytoma, and somatic VHL mutations are frequently observed in sporadic renal cancer. Here we optimize and apply saturation genome editing to assay nearly all possible single-nucleotide variants (SNVs) across VHL's coding sequence. To delineate mechanisms, we quantify mRNA dosage effects and compare functional effects in isogenic cell lines. Function scores for 2,268 VHL SNVs identify a core set of pathogenic alleles driving ccRCC with perfect accuracy, inform differential risk across tumor types and reveal new mechanisms by which variants impact function. These results have immediate utility for classifying VHL variants encountered clinically and illustrate how precise functional measurements can resolve pleiotropic and dosage-dependent genotype-phenotype relationships across complete genes.

HIF-2α expression and metabolic signaling require ACSS2 in clear cell renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC) is an aggressive cancer driven by VHL loss and aberrant HIF-2α signaling. Identifying means to regulate HIF-2α thus has potential therapeutic benefit. Acetyl-CoA synthetase 2 (ACSS2) converts acetate to acetyl-CoA and is associated with poor patient prognosis in ccRCC. Here we tested the effects of ACSS2 on HIF-2α and cancer cell metabolism and growth in ccRCC models and clinical samples. ACSS2 inhibition reduced HIF-2α levels and suppressed ccRCC cell line growth in vitro, in vivo, and in cultures of primary ccRCC patient tumors. This treatment reduced glycolytic signaling, cholesterol metabolism, and mitochondrial integrity, all of which are consistent with loss of HIF-2α. Mechanistically, ACSS2 inhibition decreased chromatin accessibility and HIF-2α expression and stability. While HIF-2α protein levels are widely regulated through pVHL-dependent proteolytic degradation, we identify a potential pVHL-independent pathway of degradation via the E3 ligase MUL1. We show that MUL1 can directly interact with HIF-2α and that overexpression of MUL1 decreased HIF-2α levels in a manner partially dependent on ACSS2. These findings identify multiple mechanisms to regulate HIF-2α stability and ACSS2 inhibition as a strategy to complement HIF-2α-targeted therapies and deplete pathogenically stabilized HIF-2α.

Regulation of the HIF switch in human endothelial and cancer cells

Hypoxia-inducible factors (HIFs) are transcription factors that reprogram the transcriptome for cells to survive hypoxic insults and oxidative stress. They are important during embryonic development and reprogram the cells to utilize glycolysis when the oxygen levels are extremely low. This metabolic change facilitates normal cell survival as well as cancer cell survival. The key feature in survival is the transition between acute hypoxia and chronic hypoxia, and this is regulated by the transition between HIF-1 expression and HIF-2/HIF-3 expression. This transition is observed in many human cancers and endothelial cells and referred to as the HIF Switch. Here we discuss the mechanisms involved in the HIF Switch in human endothelial and cancer cells which include mRNA and protein levels of the alpha chains of the HIFs. A major continuing effort in this field is directed towards determining the differences between normal and tumor cell utilization of this important pathway, and how this could lead to potential therapeutic approaches.

Deciphering anoikis resistance and identifying prognostic biomarkers in clear cell renal cell carcinoma epithelial cells

This study tackles the persistent prognostic and management challenges of clear cell renal cell carcinoma (ccRCC), despite advancements in multimodal therapies. Focusing on anoikis, a critical form of programmed cell death in tumor progression and metastasis, we investigated its resistance in cancer evolution. Using single-cell RNA sequencing from seven ccRCC patients, we assessed the impact of anoikis-related genes (ARGs) and identified differentially expressed genes (DEGs) in Anoikis-related epithelial subclusters (ARESs). Additionally, six ccRCC RNA microarray datasets from the GEO database were analyzed for robust DEGs. A novel risk prognostic model was developed through LASSO and multivariate Cox regression, validated using BEST, ULCAN, and RT-PCR. The study included functional enrichment, immune infiltration analysis in the tumor microenvironment (TME), and drug sensitivity assessments, leading to a predictive nomogram integrating clinical parameters. Results highlighted dynamic ARG expression patterns and enhanced intercellular interactions in ARESs, with significant KEGG pathway enrichment in MYC + Epithelial subclusters indicating enhanced anoikis resistance. Additionally, all ARESs were identified in the spatial context, and their locational relationships were explored. Three key prognostic genes-TIMP1, PECAM1, and CDKN1A-were identified, with the high-risk group showing greater immune infiltration and anoikis resistance, linked to poorer prognosis. This study offers a novel ccRCC risk signature, providing innovative approaches for patient management, prognosis, and personalized treatment.

HIF1α-dependent uncoupling of glycolysis suppresses tumor cell proliferation

Hypoxia-inducible factor-1α (HIF1α) attenuates mitochondrial activity while promoting glycolysis. However, lower glycolysis is compromised in human clear cell renal cell carcinomas, in which HIF1α acts as a tumor suppressor by inhibiting cell-autonomous proliferation. Here, we find that, unexpectedly, HIF1α suppresses lower glycolysis after the glyceraldehyde 3-phosphate dehydrogenase (GAPDH) step, leading to reduced lactate secretion in different tumor cell types when cells encounter a limited pyruvate supply such as that typically found in the tumor microenvironment in vivo. This is because HIF1α-dependent attenuation of mitochondrial oxygen consumption increases the NADH/NAD+ ratio that suppresses the activity of the NADH-sensitive GAPDH glycolytic enzyme. This is manifested when pyruvate supply is limited, since pyruvate acts as an electron acceptor that prevents the increment of the NADH/NAD+ ratio. Furthermore, this anti-glycolytic function provides a molecular basis to explain how HIF1α can suppress tumor cell proliferation by increasing the NADH/NAD+ ratio.

Von Hippel Lindau tumor suppressor controls m6A-dependent gene expression in renal tumorigenesis

N6-Methyladenosine (m6A) is the most abundant posttranscriptional modification, and its contribution to cancer evolution has recently been appreciated. Renal cancer is the most common adult genitourinary cancer, approximately 85% of which is accounted for by the clear cell renal cell carcinoma (ccRCC) subtype characterized by VHL loss. However, it is unclear whether VHL loss in ccRCC affects m6A patterns. In this study, we demonstrate that VHL binds and promotes METTL3/METTL14 complex formation while VHL depletion suppresses m6A modification, which is distinctive from its canonical E3 ligase role. m6A RNA immunoprecipitation sequencing (RIP-Seq) coupled with RNA-Seq allows us to identify a selection of genes whose expression may be regulated by VHL-m6A signaling. Specifically, PIK3R3 is identified to be a critical gene whose mRNA stability is regulated by VHL in a m6A-dependent but HIF-independent manner. Functionally, PIK3R3 depletion promotes renal cancer cell growth and orthotopic tumor growth while its overexpression leads to decreased tumorigenesis. Mechanistically, the VHL-m6A-regulated PIK3R3 suppresses tumor growth by restraining PI3K/AKT activity. Taken together, we propose a mechanism by which VHL regulates m6A through modulation of METTL3/METTL14 complex formation, thereby promoting PIK3R3 mRNA stability and protein levels that are critical for regulating ccRCC tumorigenesis.

Swine pseudorabies virus attenuated vaccine reprograms the kidney cancer tumor microenvironment and synergizes with PD-1 blockade

The global incidence rate of kidney cancer (KC) has been steadily increasing over the past 30 years. With the aging global population, kidney cancer has become an escalating concern that necessitates vigilant surveillance. Nowadays, surgical intervention remains the optimal therapeutic approach for kidney cancer, while the availability of efficacious treatments for advanced tumors remains limited. Oncolytic viruses, an emerging form of immunotherapy, have demonstrated encouraging anti-neoplastic properties and are progressively garnering public acceptance. However, research on oncolytic viruses in kidney cancer is relatively limited. Furthermore, given the high complexity and heterogeneity of kidney cancer, it is crucial to identify an optimal oncolytic virus agent that is better suited for its treatment. The present study investigates the oncolytic activity of the Pseudorabies virus live attenuated vaccine (PRV-LAV) against KC. The findings clearly demonstrate that PRV-LAV exhibits robust oncolytic activity targeting KC cell lines. Furthermore, the therapeutic efficacy of PRV-LAV was confirmed in both a subcutaneous tumor-bearing nude mouse model and a syngeneic mouse model of KC. Combined RNA-seq analysis and flow cytometry revealed that PRV-LAV treatment substantially enhances the infiltration of a diverse range of lymphocytes, including T cells, B cells, macrophages, and NK cells. Additionally, PRV-LAV treatment enhances T cell activation and exerts antitumor effects. Importantly, the combination of PRV-LAV with anti-PD-1 antibodies, an approved drug for KC treatment, synergistically enhances the efficacy against KC. Overall, the discovery of PRV-LAV as an effective oncolytic virus holds significant importance for improving the treatment efficacy and survival rates of KC patients.

Identification and validation of m6A-associated ferroptosis genes in renal clear cell carcinoma

Urinary cancer is synonymous with clear cell renal cell carcinoma (ccRCC). Unfortunately, existing treatments for this illness are ineffective and unpromising. Finding novel ccRCC biomarkers is crucial to creating successful treatments. The Cancer Genome Atlas provided clear cell renal cell carcinoma transcriptome data. Functional enrichment analysis was performed on ccRCC and control samples' differentially expressed N6-methyladenosine RNA methylation and ferroptosis-related genes (DEMFRGs). Machine learning was used to find and model ccRCC patients' predicted genes. A nomogram was created for clear cell renal cell carcinoma patients. Prognostic genes were enriched. We examined patients' immune profiles by risk score. Our prognostic genes predicted ccRCC treatment drugs. We found 37 DEMFRGs by comparing 1913 differentially expressed ccRCC genes to 202 m6A RNA methylation FRGs. Functional enrichment analysis showed that hypoxia-induced cell death and metabolism pathways were the most differentially expressed methylation functional regulating genes. Five prognostic genes were found by machine learning: TRIB3, CHAC1, NNMT, EGFR, and SLC1A4. An advanced renal cell carcinoma nomogram with age and risk score accurately predicted the outcome. These five prognostic genes were linked to various cancers. Immunological cell number and checkpoint expression differed between high- and low-risk groups. The risk model successfully predicted immunotherapy outcome, showing high-risk individuals had poor results. NIACIN, TAE-684, ROCILETINIB, and others treat ccRCC. We found ccRCC prognostic genes that work. This discovery may lead to new ccRCC treatments.

Understanding Factors that Influence Prognosis and Response to Therapy in Clear Cell Renal Cell Carcinoma

In this review, we highlight and contextualize emerging morphologic prognostic and predictive factors in renal cell carcinoma. We focus on clear cell renal cell carcinoma (ccRCC), the most common histologic subtype. Our understanding of the molecular characterization of ccRCC has dramatically improved in the last decade. Herein, we highlight how these discoveries have laid the foundation for new approaches to prognosis and therapeutic decision-making for patients with ccRCC. We explore the clinical relevance of common mutations, established gene expression signatures, intratumoral heterogeneity, sarcomatoid/rhabdoid morphology and PD-L1 expression, and discuss their impact on predicting response to therapy.

HIF2α Promotes Cancer Metastasis through TCF7L2-Dependent Fatty Acid Synthesis in ccRCC

Recent studies have highlighted the notable involvement of the crosstalk between hypoxia-inducible factor 2 alpha (HIF2α) and Wnt signaling components in tumorigenesis. However, the cellular function and precise regulatory mechanisms of HIF2α and Wnt signaling interactions in clear cell renal cell carcinoma (ccRCC) remain elusive. To analyze the correlation between HIF2α and Wnt signaling, we utilized the Cancer Genome Atlas - Kidney Renal Clear Cell Carcinoma (TCGA-KIRC) public database, HIF2α RNA sequencing data, and conducted luciferase reporter assays. A Wnt-related gene set was employed to identify key regulators of Wnt signaling controlled by HIF2α in ccRCC. Furthermore, we assessed the biological effects of TCF7L2 on ccRCC metastasis and lipid metabolism in both in vivo and in vitro settings. Our outcomes confirm TCF7L2 as a key gene involved in HIF2α-mediated regulation of the canonical Wnt pathway. Functional studies demonstrate that TCF7L2 promotes metastasis in ccRCC. Mechanistic investigations reveal that HIF2α stabilizes TCF7L2 mRNA in a method based on m6A by transcriptionally regulating METTL3. Up-regulation of TCF7L2 enhances cellular fatty acid oxidation, which promotes histone acetylation. This facilitates the transcription of genes connected to epithelial-mesenchymal transition and ultimately enhances metastasis of ccRCC. These outcomes offer a novel understanding into the involvement of lipid metabolism in the signaling pathway regulation, offering valuable implications for targeted treatment in ccRCC.

Kinome-wide siRNA screen identifies a DCLK2-TBK1 oncogenic signaling axis in clear cell renal cell carcinoma

TANK-binding kinase 1 (TBK1) is a potential therapeutic target in multiple cancers, including clear cell renal cell carcinoma (ccRCC). However, targeting TBK1 in clinical practice is challenging. One approach to overcome this challenge would be to identify an upstream TBK1 regulator that could be targeted therapeutically in cancer specifically. In this study, we perform a kinome-wide small interfering RNA (siRNA) screen and identify doublecortin-like kinase 2 (DCLK2) as a TBK1 regulator in ccRCC. DCLK2 binds to and directly phosphorylates TBK1 on Ser172. Depletion of DCLK2 inhibits anchorage-independent colony growth and kidney tumorigenesis in orthotopic xenograft models. Conversely, overexpression of DCLK2203, a short isoform that predominates in ccRCC, promotes ccRCC cell growth and tumorigenesis in vivo. Mechanistically, DCLK2203 elicits its oncogenic signaling via TBK1 phosphorylation and activation. Taken together, these results suggest that DCLK2 is a TBK1 activator and potential therapeutic target for ccRCC.

HIF-2α/LINC02609/APOL1-mediated lipid storage promotes endoplasmic reticulum homeostasis and regulates tumor progression in clear-cell renal cell carcinoma

BACKGROUND

The VHL-HIF pathway and lipid droplet accumulation are the main characteristics of clear cell renal cell carcinoma (ccRCC). However, the connection between the two features is largely unknown.

METHODS

We used transcriptional sequencing and TCGA database analysis to identify APOL1 as a novel therapeutic target for ccRCC. The oncogenic functions of APOL1 were investigated by cell proliferation, colony formation, migration and invasion assays in ccRCC cells in vitro and xenografts derived from ccRCC cells in vivo. Oil red O staining and quantification were used to detect lipid droplets. Chromatin immunoprecipitation (ChIP) assays and luciferase reporter assays were carried out to identify HIF-2α bound to the promoter of APOL1 and lncRNA LINC02609. RNA-FISH and luciferase reporter assays were performed to determine that LncRNA LINC02609 functions as a competing endogenous RNA to regulate APOL1 expression by sponging miR-149-5p.

FINDINGS

RNA-seq data revealed that HIF2α can regulate APOL1 and lncRNA LINC02609 expression. We also found that HIF-2α can bind to the promoter of APOL1 and lncRNA LINC02609 and transcriptionally regulate their expression directly. We further demonstrated that LncRNA LINC02609 functions as a competing endogenous RNA to regulate APOL1 expression by sponging miR-149-5p in ccRCC. Mechanistically, APOL1-dependent lipid storage is required for endoplasmic reticulum (ER) homeostasis and cell viability and metastasis in ccRCC. We also showed that high APOL1 expression correlated with worse clinical outcomes, and knockdown of APOL1 inhibited tumor cell lipid droplet formation, proliferation, metastasis and xenograft tumor formation abilities. Together, our studies identify that HIF2α can regulate the expression of the lipid metabolism related gene APOL1 by direct and indirect means, which are essential for ccRCC tumorigenesis.

INTERPRETATION

Based on the experimental data, in ccRCC, the HIF-2α/LINC02609/APOL1 axis can regulate the expression of APOL1, thus interfering with lipid storage, promoting endoplasmic reticulum homeostasis and regulating tumor progression in ccRCC. Together, our findings provide potential biomarkers and novel therapeutic targets for future studies in ccRCC.

Copper drives remodeling of metabolic state and progression of clear cell renal cell carcinoma

Copper (Cu) is an essential trace element required for mitochondrial respiration. Late-stage clear cell renal cell carcinoma (ccRCC) accumulates Cu and allocates it to mitochondrial cytochrome c oxidase. We show that Cu drives coordinated metabolic remodeling of bioenergy, biosynthesis and redox homeostasis, promoting tumor growth and progression of ccRCC. Specifically, Cu induces TCA cycle-dependent oxidation of glucose and its utilization for glutathione biosynthesis to protect against H 2 O 2 generated during mitochondrial respiration, therefore coordinating bioenergy production with redox protection. scRNA-seq determined that ccRCC progression involves increased expression of subunits of respiratory complexes, genes in glutathione and Cu metabolism, and NRF2 targets, alongside a decrease in HIF activity, a hallmark of ccRCC. Spatial transcriptomics identified that proliferating cancer cells are embedded in clusters of cells with oxidative metabolism supporting effects of metabolic states on ccRCC progression. Our work establishes novel vulnerabilities with potential for therapeutic interventions in ccRCC. Accumulation of copper is associated with progression and relapse of ccRCC and drives tumor growth.Cu accumulation and allocation to cytochrome c oxidase (CuCOX) remodels metabolism coupling energy production and nucleotide biosynthesis with maintenance of redox homeostasis.Cu induces oxidative phosphorylation via alterations in the mitochondrial proteome and lipidome necessary for the formation of the respiratory supercomplexes. Cu stimulates glutathione biosynthesis and glutathione derived specifically from glucose is necessary for survival of Cu Hi cells. Biosynthesis of glucose-derived glutathione requires activity of glutamyl pyruvate transaminase 2, entry of glucose-derived pyruvate to mitochondria via alanine, and the glutamate exporter, SLC25A22. Glutathione derived from glucose maintains redox homeostasis in Cu-treated cells, reducing Cu-H 2 O 2 Fenton-like reaction mediated cell death. Progression of human ccRCC is associated with gene expression signature characterized by induction of ETC/OxPhos/GSH/Cu-related genes and decrease in HIF/glycolytic genes in subpopulations of cancer cells. Enhanced, concordant expression of genes related to ETC/OxPhos, GSH, and Cu characterizes metabolically active subpopulations of ccRCC cells in regions adjacent to proliferative subpopulations of ccRCC cells, implicating oxidative metabolism in supporting tumor growth.

[The development of innovative therapeutic drugs targeting hypoxia responses]

The 2019 Nobel Prize in Physiology or Medicine was awarded to Dr. William G. Kaelin Jr, Dr. Peter J. Ratcliffe, and Dr. Gregg L. Semenza for their elucidation of new physiological mechanisms "How cells sense and adapt to oxygen availability". Moreover, two different drugs, HIF-PH inhibitors and HIF-2 inhibitors were also developed based on the discovery. Interestingly, those three doctors have different backgrounds as a medical oncologist, a nephrologist, and a pediatrician, respectively. They have started the research based on their own unique perspectives and eventually merged as "the elucidation of the response mechanism of living organisms to hypoxic environments". In this review, we will explain how the translational research that has begun to solve unmet clinical needs successfully contributed to the development of innovative therapeutic drugs.

Evolution of the HIF targeted therapy in clear cell renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC) is the most common type of kidney cancer, affecting hundreds of thousands of people worldwide and can affect people of any age. The pathogenesis of ccRCC is most commonly due to biallelic loss of the tumor suppressor gene VHL. VHL is the recognition subunit of an E3-ubiquitin-ligase-complex essential for degradation of the hypoxia-inducible factors (HIF) 1α and 2α. Dysfunctional degradation of HIF results in overaccumulation, which is particularly concerning with the HIF2α subunit. This leads to nuclear translocation, dimerization, and transactivation of numerous HIF-regulated genes responsible for cell survival and proliferation in ccRCC. FDA-approved therapies for RCC have primarily focused on targeting downstream effectors of HIF, then incorporated immunotherapeutics, and now, novel approaches are moving back to HIF with a focus on interfering with upstream targets. This review summarizes the role of HIF in the pathogenesis of ccRCC, novel HIF2α-focused therapeutic approaches, and opportunities for ccRCC treatment.

Inflammation and Immunity Gene Expression Patterns and Machine Learning Approaches in Association with Response to Immune-Checkpoint Inhibitors-Based Treatments in Clear-Cell Renal Carcinoma

Clear cell renal cell carcinoma (ccRCC) is the most common renal cancer. Despite the rapid evolution of targeted therapies, immunotherapy with checkpoint inhibition (ICI) as well as combination therapies, the cure of metastatic ccRCC (mccRCC) is infrequent, while the optimal use of the various novel agents has not been fully clarified. With the different treatment options, there is an essential need to identify biomarkers to predict therapeutic efficacy and thus optimize therapeutic approaches. This study seeks to explore the diversity in mRNA expression profiles of inflammation and immunity-related circulating genes for the development of biomarkers that could predict the effectiveness of immunotherapy-based treatments using ICIs for individuals with mccRCC. Gene mRNA expression was tested by the RT2 profiler PCR Array on a human cancer inflammation and immunity crosstalk kit and analyzed for differential gene expression along with a machine learning approach for sample classification. A number of mRNAs were found to be differentially expressed in mccRCC with a clinical benefit from treatment compared to those who progressed. Our results indicate that gene expression can classify these samples with high accuracy and specificity.

Somatic EPAS1 Variants in Pheochromocytoma and Paraganglioma in Patients With Sickle Cell Disease

CONTEXT

Somatic EPAS1 variants account for 5% to 8% of all pheochromocytoma and paragangliomas (PPGL) but are detected in over 90% of PPGL in patients with congenital cyanotic heart disease, where hypoxemia may select for EPAS1 gain-of-function variants. Sickle cell disease (SCD) is an inherited hemoglobinopathy associated with chronic hypoxia and there are isolated reports of PPGL in patients with SCD, but a genetic link between the conditions has yet to be established.

OBJECTIVE

To determine the phenotype and EPAS1 variant status of patients with PPGL and SCD.

METHODS

Records of 128 patients with PPGL under follow-up at our center from January 2017 to December 2022 were screened for SCD diagnosis. For identified patients, clinical data and biological specimens were obtained, including tumor, adjacent non-tumor tissue and peripheral blood. Sanger sequencing of exons 9 and 12 of EPAS1, followed by amplicon next-generation sequencing of identified variants was performed on all samples.

RESULTS

Four patients with both PPGL and SCD were identified. Median age at PPGL diagnosis was 28 years. Three tumors were abdominal paragangliomas and 1 was a pheochromocytoma. No germline pathogenic variants in PPGL-susceptibility genes were identified in the cohort. Genetic testing of tumor tissue detected unique EPAS1 variants in all 4 patients. Variants were not detected in the germline, and 1 variant was detected in lymph node tissue of a patient with metastatic disease.

CONCLUSION

We propose that somatic EPAS1 variants may be acquired through exposure to chronic hypoxia in SCD and drive PPGL development. Future work is needed to further characterize this association.

Genetic and Epigenetic Characteristics in Isolated Pancreatic Metastases of Clear-Cell Renal Cell Carcinoma

Isolated pancreatic metastases of renal cell carcinoma (IsPMRCC) are a rare manifestation of metastatic, clear-cell renal cell carcinoma (RCC) in which distant metastases occur exclusively in the pancreas. In addition to the main symptom of the isolated occurrence of pancreatic metastases, the entity surprises with additional clinical peculiarities: (a) the unusually long interval of about 9 years between the primary RCC and the onset of pancreatic metastases; (b) multiple pancreatic metastases occurring in 36% of cases; (c) favourable treatment outcomes with a 75% 5-year survival rate; and (d) volume and growth-rate dependent risk factors generally accepted to be relevant for overall survival in metastatic surgery are insignificant in isPMRCC. The genetic and epigenetic causes of exclusive pancreatic involvement have not yet been investigated and are currently unknown. Conversely, according to the few available data in the literature, the following genetic and epigenetic peculiarities can already be identified as the cause of the protracted course: 1. high genetic stability of the tumour cell clones in both the primary tumour and the pancreatic metastases; 2. a low frequency of copy number variants associated with aggressiveness, such as 9p, 14q and 4q loss; 3. in the chromatin-modifying genes, a decreased rate of PAB1 (3%) and an increased rate of PBRM1 (77%) defects are seen, a profile associated with a favourable course; 4. an increased incidence of KDM5C mutations, which, in common with increased PBRM1 alterations, is also associated with a favourable outcome; and 5. angiogenetic biomarkers are increased in tumour tissue, while inflammatory biomarkers are decreased, which explains the good response to TKI therapy and lack of sensitivity to IT.

Preliminary Study of Whole-Genome Bisulfite Sequencing and Transcriptome Sequencing in VHL Disease-Associated ccRCC

BACKGROUND

Von Hippel-Lindau (VHL) disease is an autosomal dominant hereditary tumor syndrome with an incidence of approximately 1/36,000. VHL disease-associated clear cell renal cell carcinoma (ccRCC) is the most common congenital RCC. Although recent advances in treating RCC have improved the long-term prognosis of patients with VHL disease, kidney cancer is still the leading cause of death in these patients. Therefore, finding new targets for diagnosing and treating VHL disease-associated ccRCC is still essential.

METHODS

In this study, we collected matched tumor tissues and normal samples from 25 patients with VHL disease-associated ccRCC, diagnosed and surgically treated in the Department of Urology, Peking University First Hospital. After screening, we performed whole genome bisulfite sequencing (WGBS) on 23 pairs of tissues and RNA-seq on 6 pairs of tissues. And we also compared the VHL disease-associated ccRCC transcriptome data with the sporadic ccRCC transcriptome data from the The Cancer Genome Atlas (TCGA) public database RESULTS: We found that the methylation level of VHL disease-associated ccRCC tumor tissues was significantly lower than that of normal tissues. The tumor tissues showed a difference in the copy number of 3p loss and 5q and 7q gain compared with normal tissues. We integrated RNA-seq and WGBS data to reveal methylation candidate genes associated with VHL disease-associated ccRCC; our results showed 124 hypermethylated and downregulated genes, and 245 hypomethylated and upregulated genes. By comparing the VHL disease-associated ccRCC transcriptome data with the sporadic ccRCC transcriptome data from the TCGA public database, we found that the major pathways of differential gene enrichment differed between them.

CONCLUSIONS

Our study mapped the multiomics of copy number variation, methylation and mRNA level changes in tumor and normal tissues of clear cell renal cell carcinoma with VHL syndrome, which provides a solid foundation for the mechanistic study, biomarker screening, and therapeutic target discovery of clear cell renal cell carcinoma.

Validation of prognostic signature and exploring the immune-related mechanisms for NR3C2 in clear cell renal cell carcinoma

Background

Previous studies have verified that NR3C2 inhibits tumor cell proliferation, invasion, and migration. However, there is a lack of independent validation cohorts for verifying the prognostic value of NR3C2 in clear cell renal cell carcinoma (ccRCC), and its underlying antitumor mechanisms remain unclear.

Methods

We first obtained dates from the online public databases. Then R language or online public database was used for bioinformatics analyses to evaluate the effect of NR3C2 on the diagnosis, prognosis, and immune microenvironment in ccRCC patients. Finally, the results were verified by our own cohort and immunofluorescence (IF) staining.

Results

The present study yielded significant findings regarding the expression of NR3C2 in ccRCC compared to control tissues. Specifically, NR3C2 expression was found to be significantly reduced in ccRCC and was observed to be correlated with tumor stage. Additionally, patients with lower NR3C2 expression exhibited shorter overall survival (OS), disease-specific survival, and progress-free survival. Univariable and multivariate Cox analyses further identified NR3C2 expression as an independent prognostic factor for ccRCC. Receiver operating characteristic (ROC) analysis demonstrated that NR3C2 was a highly accurate marker for distinguishing tumors from normal kidney tissue, with an area under the curve (AUC) of 0.959. Further analyses using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis suggested that NR3C2 may play a role in various biological processes and pathways related to tumor immune microenvironment (TIM). The expression of NR3C2 exhibited significant positive correlations with the levels of infiltration of CD4+ and CD8+ T cells, as well as an association with immune checkpoints.

Conclusions

Our exploratory study suggested that NR3C2 could serve as a novel biomarker for predicting survival in patients with ccRCC and the molecular mechanisms owe partly to immune cell infiltration.

The signaling pathway of hypoxia inducible factor in regulating gut homeostasis

Hypoxia represent a condition in which an adequate amount of oxygen supply is missing in the body, and it could be caused by a variety of diseases, including gastrointestinal disorders. This review is focused on the role of hypoxia in the maintenance of the gut homeostasis and related treatment of gastrointestinal disorders. The effects of hypoxia on the gut microbiome and its role on the intestinal barrier functionality are also covered, together with the potential role of hypoxia in the development of gastrointestinal disorders, including inflammatory bowel disease and irritable bowel syndrome. Finally, we discussed the potential of hypoxia-targeted interventions as a novel therapeutic approach for gastrointestinal disorders. In this review, we highlighted the importance of hypoxia in the maintenance of the gut homeostasis and the potential implications for the treatment of gastrointestinal disorders.

AXL is required for hypoxia-mediated hypoxia-inducible factor-1 alpha function in glioblastoma

Glioblastoma (GBM) is the most aggressive type of central nervous system tumor. Molecular targeting may be important when developing efficient GBM treatment strategies. Sequencing of GBMs revealed that the receptor tyrosine kinase (RTK)/RAS/phosphatidylinositol-3-kinase pathway was altered in 88% of samples. Interestingly, AXL, a member of RTK, was proposed as a promising target in glioma therapy. However, the molecular mechanism of AXL modulation of GBM genesis and proliferation is still unclear. In this study, we investigated the expression and localization of hypoxia-inducible factor-1 alpha (HIF-1α) by AXL in GBM. Both AXL mRNA and protein are overexpressed in GBM. Short-interfering RNA knockdown of AXL in U251-MG cells reduced viability and migration. However, serum withdrawal reduced AXL expression, abolishing the effect on viability. AXL is also involved in hypoxia regulation. In hypoxic conditions, the reduction of AXL decreased the level and nuclear localization of HIF-1α. The co-expression of HIF-1α and AXL was found in human GBM samples but not normal tissue. This finding suggests a mechanism for GBM proliferation and indicates that targeting AXL may be a potential GBM therapeutic.

Supplementary Information

The online version contains supplementary material available at 10.1007/s43188-023-00195-z.

von-Hippel Lindau and Hypoxia-Inducible Factor at the Center of Renal Cell Carcinoma Biology

The most common form of kidney cancer is clear cell renal cell carcinoma (ccRCC). Biallelic VHL tumor suppressor gene inactivation is the usual initiating event in both hereditary (VHL Disease) and sporadic ccRCCs. The VHL protein, pVHL, earmarks the alpha subunits of the HIF transcription factor for destruction in an oxygen-dependent manner. Deregulation of HIF2 drives ccRCC pathogenesis. Drugs inhibiting the HIF2-responsive growth factor VEGF are now mainstays of ccRCC treatment. A first-in-class allosteric HIF2 inhibitor was recently approved for treating VHL Disease-associated neoplasms and appears active against sporadic ccRCC in early clinical trials.

Targeting HIF-2 Alpha in Renal Cell Carcinoma

OPINION STATEMENT

Current treatment options for patients with metastatic renal cell carcinoma (mRCC) are limited to immunotherapy with checkpoint inhibitors and targeted therapies that inhibit the vascular endothelial growth factor receptors (VEFG-R) and the mammalian target of rapamycin (mTOR). Despite significantly improved outcomes over the last few decades, most patients with mRCC will ultimately develop resistance to these therapies, thus highlighting the critical need for novel treatment options. As part of the VHL-HIF-VEGF axis that rests at the foundation of RCC pathogenesis, hypoxia-inducible factor 2α (HIF-2α) has been identified as a rationale target for mRCC treatment. Indeed, one such agent (belzutifan) is already approved for VHL-associated RCC and other VHL-associated neoplasms. Early trials of belzutifan indicate encouraging efficacy and good tolerability in sporadic mRCC as well. The potential inclusion of belzutifan and other HIF-2α inhibitors into the mRCC treatment armamentarium either as a single agent or as combination therapy would be a welcome addition for patients with mRCC.

Morphological and molecular-biological features of glioblastoma progression in tolerant and susceptible to hypoxia Wistar rats

Hypoxia is a major pathogenetic factor in many cancers. Individual resistance to suboptimal oxygen availability is subject to broad variation and its possible role in tumorigenesis remains underexplored. This study aimed at specific characterization of glioblastoma progression in male tolerant and susceptible to hypoxia Wistar rats. Hypoxia resistance was assessed by gasping time measurement in an 11,500 m altitude-equivalent hypobaric decompression chamber. Based on the outcome, the animals were assigned to three groups termed 'tolerant to hypoxia' (n = 13), 'normal', and 'susceptible to hypoxia' (n = 24). The 'normal' group was excluded from subsequent experiments. One month later, the animals underwent inoculation with rat glioblastoma 101.8 followed by monitoring of survival, body weight dynamics and neurological symptoms. The animals were sacrificed on post-inoculation days 11 (subgroup 1) and 15 (subgroup 2). Relative vessels number, necrosis areas and Ki-67 index were assessed microscopically; tumor volumes were determined by 3D reconstruction from histological images; serum levels of HIF-1α, IL-1β, and TNFα were determined by ELISA. None of the tolerant to hypoxia animals died of the disease during observation period, cf. 85% survival on day 11 and 55% survival on day 15 in the susceptible group. On day 11, proliferative activity of the tumors in the tolerant animals was higher compared with the susceptible group. On day 15, proliferative activity, necrosis area and volume of the tumors in the tolerant to hypoxia animals were higher compared with the susceptible group. ELISA revealed no dynamics in TNFα levels, elevated levels of IL-1β in the susceptible animals on day 15 in comparison with day 11 and tolerant ones. Moreover, there were elevated levels of HIF-1α in the tolerant animals on day 15 in comparison with day 11. Thus, the proliferative activity of glioblastoma cells and the content of HIF-1α were higher in tolerant to hypoxia rats, but the mortality associated with the tumor process and IL-1β level in them were lower than in susceptible animals. Specific features of glioblastoma 101.8 progression in tolerant and susceptible to hypoxia rats, including survival, tumor growth rates and IL-1β level, can become the basis of new personalized approaches for cancer diseases treatment in accordance to individual hypoxia resistance.

An antioxidant response element regulates the HIF1α axis in breast cancer cells

The redox sensitive transcription factor NRF2 is a central regulator of the transcriptional response to reactive oxygen species (ROS). NRF2 is widely recognized for its ROS-responsive upregulation of antioxidant genes that are essential for mitigating the damaging effects of oxidative stress. However, multiple genome-wide approaches have suggested that NRF2's regulatory reach extends well beyond the canonical antioxidant genes, with the potential to regulate many noncanonical target genes. Recent work from our lab and others suggests HIF1A, which encodes the hypoxia-responsive transcription factor HIF1α, is one such noncanonical NRF2 target. These studies found that NRF2 activity is associated with high HIF1A expression in multiple cellular contexts, HIF1A expression is partially dependent on NRF2, and there is a putative NRF2 binding site (antioxidant response element, or ARE) approximately 30 kilobases upstream of HIF1A. These findings all support a model in which HIF1A is a direct target of NRF2, but did not confirm the functional importance of the upstream ARE in HIF1A expression. Here we use CRISPR/Cas9 genome editing to mutate this ARE in its genomic context and test the impact on HIF1A expression. We find that mutation of this ARE in a breast cancer cell line (MDA-MB-231) eliminates NRF2 binding and decreases HIF1A expression at the transcript and protein levels, and disrupts HIF1α target genes as well as phenotypes driven by these HIF1α targets. Taken together, these results indicate that this NRF2 targeted ARE plays an important role in the expression of HIF1A and activity of the HIF1α axis in MDA-MB-231 cells.

Novel cancer treatment paradigm targeting hypoxia-induced factor in conjunction with current therapies to overcome resistance

Chemotherapy, radiotherapy, targeted therapy, and immunotherapy are established cancer treatment modalities that are widely used due to their demonstrated efficacy against tumors and favorable safety profiles or tolerability. Nevertheless, treatment resistance continues to be one of the most pressing unsolved conundrums in cancer treatment. Hypoxia-inducible factors (HIFs) are a family of transcription factors that regulate cellular responses to hypoxia by activating genes involved in various adaptations, including erythropoiesis, glucose metabolism, angiogenesis, cell proliferation, and apoptosis. Despite this critical function, overexpression of HIFs has been observed in numerous cancers, leading to resistance to therapy and disease progression. In recent years, much effort has been poured into developing innovative cancer treatments that target the HIF pathway. Combining HIF inhibitors with current cancer therapies to increase anti-tumor activity and diminish treatment resistance is one strategy for combating therapeutic resistance. This review focuses on how HIF inhibitors could be applied in conjunction with current cancer treatments, including those now being evaluated in clinical trials, to usher in a new era of cancer therapy.

The Effect of Hypoxia-inducible Factor Inhibition on the Phenotype of Fibroblasts in Human and Bovine Pulmonary Hypertension

Hypoxia-inducible factor (HIF) has received much attention as a potential pulmonary hypertension (PH) treatment target because inhibition of HIF reduces the severity of established PH in rodent models. However, the limitations of small-animal models of PH in predicting the therapeutic effects of pharmacologic interventions in humans PH are well known. Therefore, we sought to interrogate the role of HIFs in driving the activated phenotype of PH cells from human and bovine vessels. We first established that pulmonary arteries (PAs) from human and bovine PH lungs exhibit markedly increased expression of direct HIF target genes (CA9, GLUT1, and NDRG1), as well as cytokines/chemokines (CCL2, CSF2, CXCL12, and IL6), growth factors (FGF1, FGF2, PDGFb, and TGFA), and apoptosis-resistance genes (BCL2, BCL2L1, and BIRC5). The expression of the genes found in the intact PAs was determined in endothelial cells, smooth muscle cells, and fibroblasts cultured from the PAs. The data showed that human and bovine pulmonary vascular fibroblasts from patients or animals with PH (termed PH-Fibs) were the cell type that exhibited the highest level and the most significant increases in the expression of cytokines/chemokines and growth factors. In addition, we found that human, but not bovine, PH-Fibs exhibit consistent misregulation of HIFα protein stability, reduced HIF1α protein hydroxylation, and increased expression of HIF target genes even in cells grown under normoxic conditions. However, whereas HIF inhibition reduced the expression of direct HIF target genes, it had no impact on other "persistently activated" genes. Thus, our study indicated that HIF inhibition alone is not sufficient to reverse the persistently activated phenotype of human and bovine PH-Fibs.

Selective HIF2A Inhibitors in the Management of Clear Cell Renal Cancer and Von Hippel-Lindau-Disease-Associated Tumors

Von Hippel-Lindau (VHL) loss is the hallmark event characterizing the clear cell renal cancer subtype (ccRCC). Carriers of germinal VHL mutations have an increased prevalence of kidney cysts and ccRCC as well as hemangioblastoma, pheochromocytoma and pancreatic neuroendocrine tumors. In both sporadic and inherited ccRCC, the primary mechanism of VHL-mediated carcinogenesis is the abnormal stabilization of hypoxia-inducible factors (HIF1A and HIF2A). While HIF1A acts as a tumor suppressor and is frequently lost through inactivating mutations/14q chromosome deletions, HIF2A acts as an oncogene promoting the expression of its target genes (VEGF, PDGF, CAIX Oct4, among others). Selective HIF2a inhibitors block the heterodimerization between HIF2A and ARNT, stopping HIF2A-induced transcription. Several HIF2A inhibitors have entered clinical trials, where they have shown a favorable toxicity profile, characterized by anemia, fatigue and edema and promising activity in heavily pretreated ccRCC patients. Belzutifan, a second-generation HIF2a inhibitor, was the first to receive FDA approval for the treatment of unresectable ccRCC in VHL syndrome. In this review, we recapitulate the rationale for HIF2a blockade in ccRCC, summarize the development of HIF2a inhibitors from preclinical models up to its introduction to the clinic with emphasis on Belzutifan, and discuss their role in VHL disease management.

Neurological applications of belzutifan in von Hippel-Lindau disease

Von Hippel-Lindau (VHL) disease is a tumor predisposition syndrome caused by mutations in the VHL gene that presents with visceral neoplasms and growths, including clear cell renal cell carcinoma, and central nervous system manifestations, such as hemangioblastomas of the brain and spine. The pathophysiology involves dysregulation of oxygen sensing caused by the inability to degrade HIFα, leading to the overactivation of hypoxic pathways. Hemangioblastomas are the most common tumors in patients with VHL and cause significant morbidity. Until recently, there were no systemic therapies available for patients that could effectively reduce the size of these lesions. Belzutifan, the first approved HIF-2α inhibitor, has demonstrated benefit in VHL-associated tumors, with a 30% response rate in hemangioblastomas and ~30%-50% reduction in their sizes over the course of treatment. Anemia is the most prominent adverse effect, affecting 76%-90% of participants and sometimes requiring dose reduction or transfusion. Other significant adverse events include hypoxia and fatigue. Overall, belzutifan is well tolerated; however, long-term data on dosing regimens, safety, and fertility are not yet available. Belzutifan holds promise for the treatment of neurological manifestations of VHL and its utility may influence the clinical management paradigms for this patient population.

Diseases of Hereditary Renal Cell Cancers

Germline mutations in tumor suppressor genes and oncogenes lead to hereditary renal cell carcinoma (HRCC) diseases, characterized by a high risk of RCC and extrarenal manifestations. Patients of young age, those with a family history of RCC, and/or those with a personal and family history of HRCC-related extrarenal manifestations should be referred for germline testing. Identification of a germline mutation will allow for testing of family members at risk, as well as personalized surveillance programs to detect the early onset of HRCC-related lesions. The latter allows for more targeted and therefore more effective therapy and better preservation of renal parenchyma.