Total loss of VHL gene function impairs neuroendocrine cancer cell fitness due to excessive HIF2α activity.

Loss-of-function germline von Hippel-Lindau (VHL) tumor suppressor mutations cause VHL disease, which predisposes individuals to kidney cancer, hemangioblastomas, and paragangliomas. The risk that a given VHL disease family will manifest some or all these tumor types is profoundly influenced by the VHL allele it carries. For example, almost all VHL disease families that develop paraganglioma have missense VHL mutations. VHL families with null VHL alleles develop kidney cancer and hemangioblastomas without a high risk of paraganglioma. The latter is surprising because the VHL gene product, pVHL, suppresses the HIF2 transcription factor and gain-of-function HIF2 mutations are also linked to paraganglioma. Paragangliomas arise from the sympathetic or parasympathetic nervous system. Given the lack of human paraganglioma cell lines, we studied the effects of inactivating VHL in neuroblastoma cell lines, which also arise from the sympathetic nervous system. We found that total loss of pVHL function profoundly impairs the fitness of neuroblastoma cell lines in a HIF2-dependent manner both ex vivo and in vivo. This fitness defect can be rescued by pVHL variants linked to paraganglioma, but not by pVHL variants associated with a low risk of paraganglioma. These findings suggest that HIF2 activity above a critical threshold prevents the development of paraganglioma.

Characterizing and predicting ccRCC-causing missense mutations in Von Hippel-Lindau disease.

BACKGROUND: Mutations within the Von Hippel-Lindau (VHL) tumor suppressor gene are known to cause VHL disease, which is characterized by the formation of cysts and tumors in multiple organs of the body, particularly clear cell renal cell carcinoma (ccRCC). A major challenge in clinical practice is determining tumor risk from a given mutation in the VHL gene. Previous efforts have been hindered by limited available clinical data and technological constraints. METHODS: To overcome this, we initially manually curated the largest set of clinically validated VHL mutations to date, enabling a robust assessment of existing predictive tools on an independent test set. Additionally, we comprehensively characterized the effects of mutations within VHL using in silico biophysical tools describing changes in protein stability, dynamics and affinity to binding partners to provide insights into the structure-phenotype relationship. These descriptive properties were used as molecular features for the construction of a machine learning model, designed to predict the risk of ccRCC development as a result of a VHL missense mutation. RESULTS: Analysis of our model showed an accuracy of 0.81 in the identification of ccRCC-causing missense mutations, and a Matthew's Correlation Coefficient of 0.44 on a non-redundant blind test, a significant improvement in comparison to the previous available approaches. CONCLUSION: This work highlights the power of using protein 3D structure to fully explore the range of molecular and functional consequences of genomic variants. We believe this optimized model will better enable its clinical implementation and assist guiding patient risk stratification and management.

The Interplay between von Hippel-Lindau Tumor Suppressor Gene, Lon Protease, ROS Accumulation, and Inflammation in Clear Cell Renal Cell Carcinoma.

This study explores the role of the von Hippel-Lindau (VHL) tumor suppressor gene and Lon protease in the development of clear cell renal carcinoma (ccRCC) through mechanisms involving inflammation and reactive oxygen species (ROS) accumulation in kidney cells. By examining the impact of VHL on the early stages of kidney cancer development, this research highlights the contributions of inflammation and ROS, as well as the involvement of Lon protease. The findings reveal increased Lon expression and ROS levels in VHL-knockdown HK-2 cells, along with elevated phospho-c-Jun N-terminal kinase (JNK) levels, emphasizing the complex interplay between VHL, Lon protease, inflammation, and ROS in kidney cell models. These insights point to potential therapeutic pathways for ccRCC.

Somatostatin receptor 2A expression in von Hippel-Lindau-related hemangioblastomas.

BACKGROUND: Central nervous system hemangioblastomas are the most prevalent manifestation of von Hippel-Lindau (VHL) disease and remain the main cause of mortality. Surgical resection is the primary treatment strategy, but is not always possible, and should be used as restrictively as possible. There is an unmet need for less invasive treatment strategies, such as targeted therapy. Expression of somatostatin receptor 2A (SSTR2A) in VHL-related hemangioblastomas has been described earlier, but the extent of expression in a larger population has yet to be determined. The authors hypothesize that a substantial subset of VHL-related hemangioblastomas show SSTR2A expression, which may serve as a potential new treatment target. METHODS: Patients who were surgically treated for a VHL-related hemangioblastoma from 1990 until 2021 at the UMC Utrecht were included. Clinical data was derived from a clinical database. Tissue samples were histopathologically examined with use of hematoxylin and eosin staining, and immunohistochemical analysis of SSTR2A expression was performed. RESULTS: Forty-three tissue samples were obtained from 26 patients. Nine showed strong positivity for SSTR2A expression, whereas 13 showed moderate and 15 sparse expression. Three samples showed no expression of SSTR2A. The distribution showed right-skewedness favoring a strong expression. SSTR2A expression colocalized with endothelial markers and not with stromal cells. Additionally, within-patient variability for SSTR2A expression was described in 14 patients. CONCLUSION: SSTR2A is expressed in varying degrees in the majority of VHL-related hemangioblastomas. Future treatment with somatostatin analogues or even peptide receptor radionuclide treatment may be considered for SSTR2A-positive cases.

The von Hippel-Lindau protein forms fibrillar amyloid assemblies that are mitigated by the anti-amyloid molecule Purpurin.

The von Hippel-Lindau protein (pVHL) is a tumor suppressor involved in oxygen regulation via dynamic nucleocytoplasmic shuttling. It plays a crucial role in cell survival by degrading hypoxia-inducible factors (HIFs). Mutations in the VHL gene cause angiogenic tumors, characterized as VHL syndrome. However, aggressive tumors involving wild-type pVHL have also been described but the underlying mechanism remains to be revealed. We have previously shown that pVHL possesses several short amyloid-forming motifs, making it aggregation-prone. In this study, using a series of biophysical assays, we demonstrated that a pVHL-derived fragment (pVHL104-140) that harbors the nuclear export motif and HIF binding site, forms amyloid-like fibrillar structures in vitro by following secondary-nucleation-based kinetics. The peptide also formed amyloids at acidic pH that mimics the tumor microenvironment. We, subsequently, validated the amyloid formation by pVHL in vitro. Using the Curli-dependent amyloid generator (C-DAG) expression system, we confirmed the amyloidogenesis of pVHL in bacterial cells. The pVHL amyloids are an attractive target for therapeutics of the VHL syndrome. Accordingly, we demonstrated in vitro that Purpurin is a potent inhibitor of pVHL fibrillation. The amyloidogenic behavior of wild-type pVHL and its inhibition provide novel insights into the molecular underpinning of the VHL syndrome and its possible treatment.

Cumulative Impact of Serial Partial Nephrectomy for the Treatment of Recurrent Renal Masses.

PURPOSE: Reoperative partial nephrectomy (RePN) offers several advantages for the treatment of recurrent, multifocal renal masses. RePN has been previously demonstrated to be technically feasible and delay the need for renal replacement therapy. However, there is still inherent complexity and known risks to reoperative nephrectomy. We studied the largest population of RePNs to characterize renal functional outcomes and the likelihood of intra- and postoperative complications. MATERIALS AND METHODS: Query of an institutional surgical registry was conducted. Demographic data, serum creatinine for estimated glomerular filtration rate (eGFR), and protein dipstick results were assessed within 1 week prior to surgery, and postoperative function assessments were studied within a year of surgery. RePN was defined as serial surgical resection of the ipsilateral renal unit. RESULTS: A total of 1131 partial nephrectomies performed on 663 patients at a single center were retrospectively evaluated. In reoperative cases, median number of operations per renal unit was 2 (range: 2-6). There was a stepwise decline in eGFR with an average decline of 6.1 with each RePN. With each subsequent nephrectomy, surgical duration, estimated blood loss, and incidence of preoperative anemia increased. Postoperative eGFR showed a significant positive association with preoperative eGFR, while negative associations were found with age, number of previous ipsilateral partial nephrectomies, number of tumors, and largest tumor size. High-grade complications were associated with the number of ipsilateral partial nephrectomies, tumor count, and tumor size. Robotic or laparoscopic procedures exhibited a likelihood of grade 3 or greater complications compared to open surgery. CONCLUSIONS: RePN contributes to renal dysfunction and an increased risk of surgical complications. Intraoperative blood loss and surgical duration increase with subsequent nephrectomy. Such risks are dependent on the number of prior operative interventions on the kidney, suggesting a stepwise progression of surgical morbidity.

Consensus Guidelines for Ocular Surveillance of von Hippel-Lindau Disease.

PURPOSE: To develop guidelines for ocular surveillance and early intervention for individuals with von Hippel-Lindau (VHL) disease. DESIGN: Systematic review of the literature. PARTICIPANTS: Expert panel of retina specialists and ocular oncologists. METHODS: A consortium of experts on clinical management of all-organ aspects of VHL disease was convened. Working groups with expertise in organ-specific features of VHL disease were tasked with development of evidence-based guidelines for each organ system. The ophthalmology subcommittee formulated questions for consideration and performed a systematic literature review. Evidence was graded for topic quality and relevance and the strength of each recommendation, and guideline recommendations were developed. RESULTS: The quality of evidence was limited, and no controlled clinical trial data were available. Consensus guidelines included: (1) individuals with known or suspected VHL disease should undergo periodic ocular screening (evidence type, III; evidence strength, C; degree of consensus, 2A); (2) patients at risk of VHL disease, including first-degree relatives of patients with known VHL disease, or any patient with single or multifocal retinal hemangioblastomas (RHs), should undergo genetic testing for pathologic VHL disease gene variants as part of an appropriate medical evaluation (III/C/2A); (3) ocular screening should begin within 12 months after birth and continue throughout life (III/C/2A); (4) ocular screening should occur approximately every 6 to 12 months until 30 years of age and then at least yearly thereafter (III/C-D/2A); (5) ocular screening should be performed before a planned pregnancy and every 6 to 12 months during pregnancy (IV/D/2A); (6) ultra-widefield color fundus photography may be helpful in certain circumstances to monitor RHs, and ultra-widefield fluorescein angiography may be helpful in certain circumstances to detect small RHs (IV/D/2A); (7) patients should be managed, whenever possible, by those with subspecialty training, with experience with VHL disease or RHs, or with both and ideally within the context of a multidisciplinary center capable of providing multiorgan surveillance and access to genetic testing (IV/D/2A); (8) extramacular or extrapapillary RHs should be treated promptly (III/C/2A). CONCLUSIONS: Based on available evidence from observational studies, broad agreement was reached for a strategy of lifelong surveillance and early treatment for ocular VHL disease. These guidelines were endorsed by the VHL Alliance and the International Society of Ocular Oncology and were approved by the American Academy of Ophthalmology Board of Trustees. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Oral Hypoxia-Inducible Factor 2α Inhibitor Belzutifan in Ocular von Hippel-Lindau Disease: Subgroup Analysis of the Single-Arm Phase 2 LITESPARK-004 Study.

PURPOSE: To report the efficacy of the oral hypoxia-inducible factor 2α inhibitor belzutifan in participants with von Hippel-Lindau disease-associated retinal hemangioblastomas in the LITESPARK-004 study. DESIGN: Subgroup analysis of the phase 2, single-arm, open-label LITESPARK-004 study. PARTICIPANTS: Adults with 1 or more von Hippel-Lindau disease-associated measurable renal cell carcinoma tumors not requiring immediate surgical intervention were eligible. METHODS: Participants received oral belzutifan 120 mg once daily until disease progression or unacceptable treatment-related toxicity. MAIN OUTCOME MEASURES: Efficacy of belzutifan in retinal hemangioblastomas was a secondary end point, measured as response (improved, stable, or progressed) by independent reading center-certified graders based on color fundus imaging performed every 12 weeks using the investigator's preferred imaging standards. Additional assessments, where available, included OCT and ultra-widefield fluorescein angiography. RESULTS: Among 61 participants in LITESPARK-004, 12 had 1 or more evaluable active retinal hemangioblastomas in 16 eyes at baseline per independent reading center. As of April 1, 2022, the median follow-up for participants with ocular von Hippel-Lindau disease at baseline was 37.3 months. All 16 eyes were graded as improved, with a response rate of 100.0% (95% confidence interval, 79.4%-100%). No new retinal hemangioblastomas or ocular disease progression were reported as of data cutoff date. Eight participants underwent additional multimodal eye assessments performed at the National Institutes of Health study site. Among this subgroup, 10 of 24 hemangioblastomas in 8 eyes of 6 participants measured 500 µm or more in greatest linear dimension at baseline and were analyzed further. All 10 hemangioblastomas had a mean area reduction of 15% or more by month 12 and of 30% or more by month 24. CONCLUSIONS: Belzutifan showed promising activity against ocular von Hippel-Lindau disease, including capacity to control retinal hemangioblastomas, with effects sustained for more than 2 years while treatment is ongoing. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Clear Cell Renal Cell Carcinoma: Characterizing the Phenotype of Von Hippel-Lindau Mutation Using MRI.

BACKGROUND: The von Hippel-Lindau (VHL) mutation is an important alteration in clear cell renal cell carcinoma (ccRCC); however, its imaging phenotype remains unclear. PURPOSE: To investigate whether MRI features can reflect the VHL mutation status. STUDY TYPE: Retrospective. FIELD STRENGTH/SEQUENCE: 3 T/fast spin echo T2-weighted, spin-echo echo planar diffusion-weighted, gradient recalled echo T1-weighted, gradient recalled echo chemical-shift T1-weighted, and contrast-enhanced gradient recalled echo T1-weighted sequences. POPULATION: One hundred five patients with ccRCC who underwent preoperative contrast-enhanced MRI and subsequent genomic sequencing: 59 consecutive patients from our institution (38 [64.41%] with VHL mutations) formed a training cohort, and 46 from The Cancer Genome Atlas (TCGA) database (24 [52.17%] with VHL mutations) formed an independent test cohort. ASSESSMENT: Two radiologists, with 23 and 33 years of experience respectively, jointly evaluated the semantic MRI features of the primary lesion in ccRCCs to propose potential features related to VHL mutations in both cohorts. Three additional readers, with 5, 7, and 10 years of experience respectively, independently reviewed all lesions to assess the interobserver agreement of MRI features. A VHL mutational likelihood score (VHL-MULIS) system was constructed using the training cohort and validated using the independent test cohort. STATISTICAL TESTS: Fisher's test or chi-square test, t-test or Mann-Whitney U test, logistic regression, Cohen's kappa (κ), area under the receiver operating characteristic curve (AUC). A two-sided P value <0.05 was considered statistically significant. RESULTS: In both the local and public cohorts, T2-weighted signal intensity and presence of microscopic fat from primary lesions were significantly associated with VHL mutation status. The VHL-MULIS incorporated maximum diameter, T2-weighted signal intensity, and presence of microscopic fat in the training cohort and demonstrated promising diagnostic ability (AUC, 0.82; sensitivity, 0.79; specificity, 0.82) and substantial interobserver agreement (κ, 0.787) in the test cohort. DATA CONCLUSION: The VHL mutation exhibited a distinct MRI phenotype. Integrating multiple semantic MRI features has potential to reflect the mutation status in patients with ccRCC. EVIDENCE LEVEL: 3 TECHNICAL EFFICACY: Stage 2.

Screening and surveillance recommendations for central nervous system hemangioblastomas in pediatric patients with Von Hippel-Lindau disease.

PURPOSE: Von Hippel-Lindau (VHL) disease is an autosomal-dominantly inherited tumor predisposition syndrome. One of the most common tumors are central nervous system (CNS) hemangioblastomas. Recommendations on the initiation and continuation of the screening and surveillance program for CNS tumors in pediatric VHL patients are based on small case series and thus low evidence level. To derive more robust screening recommendations, we report on the largest monocentric pediatric cohort of VHL patients. METHODS: We performed a retrospective analysis on a pediatric cohort of 99 VHL patients consulted at our VHL center from 1992 to 2023. Clinical, surgical, genetic, and imaging data were collected and statistically analyzed. RESULTS: 42 patients (50% male) developed CNS hemangioblastomas, of whom 18 patients (56% male) underwent hemangioblastoma surgery (mean age at first surgery: 14.9 ± 1.9 years; range 10.2-17). The first asymptomatic patient was operated on at the age of 13.2 years due to tumor progress. Truncating VHL mutation carriers had a significantly higher manifestation rate (HR = 3.7, 95% CI: 1.9-7.4, p < 0.0001) and surgery rate (HR = 3.3, 95% CI: 1.2-8.9, p = 0.02) compared with missense mutation carriers. CONCLUSION: We recommend starting MRI imaging at the age of 12 years with examination intervals every (1-) 2 years depending on CNS involvement. Special attention should be paid to patients with truncating variants. Affected families should be educated regularly on potential tumor-associated symptoms to enable timely MRI imaging and eventually intervention, as CNS hemangioblastoma may develop before screening begins. GERMAN CLINICAL TRIALS REGISTER REGISTRATION NUMBER: DRKS00029553, date of registration 08/16/2022, retrospectively registered.

Pediatric patients with von Hippel-Lindau and hemangioblastomas treated successfully with belzutifan.

Hemangioblastoma is the most common tumor associated with von Hippel-Lindau (VHL), and are a leading cause of mortality. We present five pediatric patients with VHL-associated hemangioblastomas treated with belzutifan, a hypoxia-inducible factor 2a (HIF2a) inhibitor. Three patients were started on belzutifan due to vision loss from progressive retinal hemangioblastomas. Within one year of treatment, all three patients had improvement in hemangioblastoma size and visual acuity. For patients with intracranial lesions, belzutifan resulted in an improvement in neurologic symptoms and hemangioblastoma size. Four patients experienced grade 1-2 anemia and two patients required a dose reduction. Our report suggests that belzutifan can be an effective therapy for pediatric, adolescent, and young adult patients with VHL-associated hemangioblastomas.

Insoluble HIFa protein aggregates by cadmium disrupt hypoxia-prolyl hydroxylase (PHD)-hypoxia inducible factor (HIFa) signaling in renal epithelial (NRK-52E) and interstitial (FAIK3-5) cells.

The kidney is the main organ that senses changes in systemic O2 pressure by hypoxia-PHD-HIFa (HPH) signaling, resulting in adaptive target gene activation, including erythropoietin (EPO). The non-essential transition metal cadmium (Cd) is nephrotoxic and disrupts the renal HPH pathway, which may promote Cd-associated chronic renal disease (CKD). A deeper molecular understanding of Cd interference with renal HPH signaling is missing, and no data with renal cell lines are available. In rat kidney NRK-52E cells, which model the proximal tubule, and murine fibroblastoid atypical interstitial kidney (FAIK3-5) cells, which mimic renal EPO-producing cells, the chemical hypoxia mimetic dimethyloxalylglycine (DMOG; 1 mmol/l) or hypoxia (1% O2) activated HPH signaling. Cd2+ (2.5-20 µmol/l for ≤ 24 h) preferentially induced necrosis (trypan blue uptake) of FAIK3-5 cells at high Cd whereas NRK-52E cells specially developed apoptosis (PARP-1 cleavage) at all Cd concentrations. Cd (12.5 µmol/l) abolished HIFa stabilization and prevented upregulation of target genes (quantitative real-time polymerase chain reaction and immunoblotting) induced by DMOG or hypoxia in both cell lines, which was caused by the formation of insoluble HIFa aggregates. Strikingly, hypoxic preconditioning (1% O2 for 18 h) reduced apoptosis of FAIK3-5 and NRK-52E cells at low Cd concentrations and decreased insoluble HIFa proteins. Hence, drugs mimicking hypoxic preconditioning could reduce CKD induced by chronic low Cd exposure.

Belzutifan: a novel therapeutic for the management of von Hippel-Lindau disease and beyond.

The identification of the VHL gene and its role in regulating the hypoxia-inducible factor signaling pathway has helped to revolutionize the treatment of renal cell carcinoma (RCC). Belzutifan is a novel small-molecule inhibitor of hypoxia-inducible factor 2α which has demonstrated efficacy in treating von Hippel-Lindau (VHL) disease, earning regulatory approvals for this indication. There is also early evidence for efficacy in sporadic RCC. Belzutifan has a favorable safety profile. Several clinical trials are currently ongoing, which should help in identifying this promising drug's role in RCC and beyond. This review summarizes the history, pharmacology and clinical evidence for belzutifan use to date, and also explores unanswered questions as they relate to this novel therapeutic agent.

The novel drug belzutifan was developed after years of research in identifying the VHL gene and how genetic abnormalities in VHL may result in tumor growth. Belzutifan has been approved for use in patients with VHL disease ­ a rare familial disorder first described in the 19th century that presents with a variety of cancerous and noncancerous tumors, including kidney cancer. Growing evidence supports belzutifan's use in non-familial kidney cancer as well. This is important because most patients eventually develop resistance to the currently available cancer treatments, highlighting the need for drugs with a different mechanism of action. Belzutifan works by blocking a protein called HIF-2a, which causes tumor growth in patients with VHL disease. Belzutifan is well tolerated, with the most common side effects being low energy, hemoglobin and blood oxygen. This review summarizes the history, mechanism of action and research evidence to date supporting the use of belzutifan in VHL disease and cancer treatment. We also discuss future directions, including remaining clinical questions and areas of ongoing research.

von Hippel-Lindau-targeting microRNA-143-3p attenuates mitochondrial abnormality via AMPK/PGC-1α axis in Parkinson's disease.

Parkinson's disease (PD) is the second most common neurodegenerative disease characterized by selective loss of dopaminergic neurons. We previously found that inhibition of von Hippel-Lindau (VHL) can alleviate dopaminergic neuron degeneration in PD models via regulation of mitochondrial homeostasis, however, the disease-related alterations of VHL and the regulatory mechanisms of VHL level in PD need to be further investigated. In this study, we found that the levels of VHL were markedly increased in multiple cell models of PD and identified microRNA-143-3p (miR-143-3p) as a promising candidate for regulating VHL expression involved in PD. miR-143-3p directly bound to the 3'untranslated region of human VHL mRNA and inhibited its translation, and exerted neuroprotective effects by improving cell viability, apoptosis and tyrosine hydroxylase abnormality. Furthermore, we demonstrated that miR-143-3p exerted neuroprotection by attenuating mitochondrial abnormality via AMP-activated protein kinase (AMPK)/peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) axis, and AMPK inhibitor abolished the beneficial effects of miR-143-3p on the cell model of PD. Therefore, we identify the dysregulated VHL and miR-143-3p in PD, and propose the therapeutic potential of miR-143-3p to alleviate PD by improving mitochondrial homeostasis via AMPK/PGC-1α axis.

Percutaneous microwave ablation on management of hereditary renal cell carcinoma in Von Hippel-Lindau disease.

BACKGROUND: The effect of microwave ablation (MWA) for the renal cell carcinoma (RCC) in Von Hippel-Lindau (VHL) disease is unclear. OBJECTIVE: To assess the safety, Technique efficacy, renal function and oncological outcome of MWA for RCC in VHL patients. METHODS: Consecutive patients with RCCs in VHL disease treated by MWA were retrospectively collected from November 2009 to October 2020. The technical efficacy rate and complications were assessed. The outcomes of pre- and post-ablative eGFR were compared. The local recurrent-free survival (LRFS), renal-cancer-free survival (RCFS), cancer-specific survival (CSS), overall survival (OS) and complications were presented. RESULTS: A total of 10 patients (mean age, 39.0 years ± 10.7 [SD]; 3 women) with 28 RCCs (mean tumor size, 3.0 cm ± 0.34; mean tumor volume, 20.7 mL ± 43.3) treated with MWA were included. Th median follow-up time was 52 months(IQR:27-80). The overall technical efficacy rate was 100% with no major complications occurred. No significant statistical difference between pre-ablative and postablative creatinine level (102.0 µmol/L ± 30.4 vs 112.3 µmol/L ± 38.7, p = 0.06), but the pre-ablative eGFR level was significantly higher than the post-ablative eGFR (78.0 mL/(min*1.73m2) ± 28.6 vs 72 mL/(min*1.73m2) ± 31.4, p = 0.04), with the mean decrease of 5.86 ml/(min*1.73m2). The local recurrent-free survival(LRFS) and renal-cancer-free survival (RCFS) were 100% and 60%, respectively. The cancer specifical survival (CSS) and overall survival (OS) were 95.5% and 100%, respectively. CONCLUSION: Microwave ablation is a safe and feasible method for the treatment of RCC in VHL disease, preserving renal function and yielding satisfactory oncological outcomes.

Genome editing and cancer therapy: handling the hypoxia-responsive pathway as a promising strategy.

The precise characterization of oxygen-sensing pathways and the identification of pO2-regulated gene expression are both issues of critical importance. The O2-sensing system plays crucial roles in almost all the pivotal human processes, including the stem cell specification, the growth and development of tissues (such as embryogenesis), the modulation of intermediate metabolism (including the shift of the glucose metabolism from oxidative to anaerobic ATP production and vice versa), and the control of blood pressure. The solid cancer microenvironment is characterized by low oxygen levels and by the consequent activation of the hypoxia response that, in turn, allows a complex adaptive response characterized mainly by neoangiogenesis and metabolic reprogramming. Recently, incredible advances in molecular genetic methodologies allowed the genome editing with high efficiency and, above all, the precise identification of target cells/tissues. These new possibilities and the knowledge of the mechanisms of adaptation to hypoxia suggest the effective development of new therapeutic approaches based on the manipulation, targeting, and exploitation of the oxygen-sensor system molecular mechanisms.

The genetic differences between types 1 and 2 in von Hippel-Lindau syndrome: comprehensive meta-analysis.

BACKGROUND: Patients with von Hippel-Lindau (VHL) disease are at risk of developing tumors in the eye, brain, kidney, adrenal gland, and other organs based on their gene mutations. The VHL tumor suppressor gene contains pathogenic variants responsible for these events. This meta-analysis aims to investigate the genetic differences among the various types of VHL syndrome and their correlation with the location of mutations (exons and domains) in the VHL gene. METHOD: Papers eligible for publication until September 2023 were identified using the electronic databases of PubMed, Google Scholar, Scopus, and EMBASE. The Random Effect model was utilized to evaluate the genetic differences between type 1 and type 2 VHL syndromes. RESULTS: The prevalence of missense mutations (MSs) was found to be 58.9% in type 1, while it was 88.1% in type 2. Interestingly, the probability of observing MSs in type 1 was 0.42 times lower compared to type 2. The mutation hotspots of the VHL gene were R167Q/W, Y98H, R238W, and S65L, respectively. Although type 2 had a high presentation of Y98H and R238W, it did not have a higher S65L than type 1. The analysis demonstrated a statistically significant higher prevalence of truncated mutations (PTMs) in type 1. Among type 1, large/complete deletions (L/C DELs) were found in 16.9% of cases, whereas in type 2 only 3.7%. This difference was statistically significant with a p-value < 0.001. Overall, the probability of identifying mutations in domain 2 compared to domain 1 was found to be 2.13 times higher in type 1 (p-value < 0.001). Furthermore, the probability of detecting exon 1 in comparison with observing exon 2 in type 1 was 2.11 times higher than type 2 and revealed a statistically significant result (p-value < 0.001). The detection of exon 2 was 2.18 times higher in type 1 (p-value < 0.001). In addition, the likelihood of discovering exon 2 compared with others was significantly lower in type 1 compared with type 2 VHL (OR = 0.63, p-value = 0.015). CONCLUSIONS: We have revealed a comprehensive genetic difference between types 1 and 2 of VHL syndrome. The significant differences in MS, PTMs, L/C DELs, and the location of the mutations between type 1 and type 2 VHL patients in the Asian, European, and American populations emphasize the genetic heterogeneity of the syndrome. These findings may pave the way for the diagnosis, treatment, and further investigation of the mechanisms behind this complex genetic disorder.

von Hippel-Lindau disease-related neoplasia with an emphasis on renal manifestations.

von Hippel-Lindau (VHL) disease is characterized by biallelic inactivation of the VHL gene leading to abnormal or absent VHL protein function, and constitutive activation of hypoxia-inducible factors (HIF) that leads to pro-tumorigenic signaling. Individuals with VHL disease develop numerous cysts and tumors involving multiple organs including the kidneys, central nervous system, endolymphatic sac, lungs, pancreatobiliary system, adrenal glands, epididymis, and/or broad ligament. On histologic examination, these lesions show morphologic overlap as they are frequently characterized by cells with clear cytoplasm and prominent vascularity. In addition to distinguishing non-renal tumors from metastatic clear cell renal cell carcinoma, understanding site-specific histopathologic and immunophenotypic features of these tumors has several applications. This includes distinguishing VHL-related tumors from those that arise sporadically and lack VHL gene alterations, guiding further genetic workup, and helping distinguish between different genetic predisposition syndromes. In this context, immunohistochemical studies for markers such as paired box 8 (PAX-8), carbonic anhydrase 9 (CA9), and glucose transporter 1 (GLUT-1) have an important role in routine clinical practice and represent cost-effective diagnostic tools. The recent development of targeted therapeutics directed against HIF-mediated signaling represents a significant milestone in the management of VHL disease and highlights the importance of accurately diagnosing and characterizing the wide spectrum of VHL disease-associated lesions.

Discovering a novel genetic variant in 11 family members who had isolated pheochromocytoma linked to von Hippel-Lindau (VHL) syndrome, aligning with the type 2c phenotype.

INTRODUCTION: Von Hippel-Lindau disease (e.g. VHL) is an autosomal dominant multi-organ cancer syndrome caused by a mutation in the VHL tumour suppressor gene. In this study, we introduce a novel genetic variant found in 11 family members diagnosed initially with isolated Pheochromocytoma. Subsequent findings revealed its association with VHL syndrome and corresponds to the Type 2 C phenotype. METHODS: The VHL gene was amplified through the utilisation of the polymerase chain reaction (PCR). PCR fragments were sequenced using bidirectional Sanger sequencing, using BigDye™ Terminator v3.1 Cycle Sequencing Kit, running on the 3500 genetic analyser. Results were assembled and analysed Using Software SeqA and chromas pro. RESULTS: A heterozygous in-frame duplication of three nucleotides, specifically ATG, c.377_379dup; p.Asp126dup in exon 2, was identified in all the patients tested within the pedigree. CONCLUSION: In this study, we disclose the identification of a novel genetic variant in a Jordanian family, affecting eleven family members with pheochromocytoma associated with VHL disease. This finding underscores the importance of screening family members and contemplating genetic testing for individuals newly diagnosed with pheochromocytoma and could enhance our comprehension of the potential adverse consequences associated with VHL germline mutations.

Goal: To study a novel gene change in a family with Von Hippel-Lindau (e.g. VHL) syndrome, which increases cancer chances.Participants: 11 family members with Pheochromocytoma, a tumour linked to VHL.Methods:Used PCR to copy the VHL gene.Analysed the gene using Sanger sequencing.Findings:Found a novel gene change in all family members. This change, called an in-frame duplication, affects a protein.It's in a specific part of the gene.Conclusion:Stressing the importance of genetic testing for Pheochromocytoma patients to grasp VHL mutation risks.

How I do it: cervical hemangioblastoma resection. Surgical technique and complication avoidance.

BACKGROUND: Spinal cord hemangioblastomas are benign, highly vascular neoplasms that affect the brain and, rarely, the spinal cord. They can be solitary or as part of von Hippel-Lindau syndrome. Radiosurgery is not a suitable treatment option. Endovascular embolization can only be adjunct to surgery. METHOD: We present a detailed approach to resection of a spinal cord hemangioblastoma. A video demonstrates the microsurgical technique and discusses complication avoidance. CONCLUSION: The pitfalls to consider are preservation of normal spinal cord vessels, protection of the pia-arachnoid cleavage plane, and avoidance of tumor piecemeal removal. Careful microsurgical resection and detailed preoperative planning are key.