scholarly journals VHLGenetic Alteration in CCRCC Does Not Determine De-Regulation of HIF, CAIX, hnRNP A2/B1 and Osteopontin

2010 ◽  
Vol 33 (3-4) ◽  
pp. 121-132 ◽  
Author(s):  
Michelle J. Nyhan ◽  
Shereen M. El Mashad ◽  
Tracey R. O’Donovan ◽  
Sarfraz Ahmad ◽  
Chris Collins ◽  
...  
Keyword(s):  
Hypoxia Inducible Factor ◽  
Suppressor Gene ◽  
Genetic Alterations ◽  
Tumour Suppressor Gene ◽  
Cell Renal Cell Carcinoma ◽  
Protein Targets ◽  
Renal Carcinogenesis ◽  
Von Hippel Lindau ◽  
The Impact

Background: von Hippel–Lindau (VHL) tumour suppressor gene inactivation is associated with clear cell renal cell carcinoma (CCRCC) development. The VHL protein (pVHL) has been proposed to regulate the expression of several proteins including Hypoxia Inducible Factor-α (HIF-α), carbonic anhydrase (CA)IX, heterogeneous nuclear ribonucleoprotein (hnRNP) A2/B1 and osteopontin. pVHL has been characterized in vitro, however, clinical studies are limited. We evaluated the impact of VHL genetic alterations on the expression of several pVHL protein targets in paired normal and tumor tissue.Methods: TheVHLgene was sequenced in 23 CCRCC patients andVHLtranscript levels were evaluated by real-time RT-PCR. Expression of pVHL’s protein targets were determined by Western blotting in 17 paired patient samples.Results: VHL genetic alterations were identified in 43.5% (10/23) of CCRCCs. HIF-1α, HIF-2α and CAIX were up-regulated in 88.2% (15/17), 100% (17/17) and 88.2% (15/17) of tumors respectively and their expression is independent ofVHLstatus. hnRNP A2/B1 and osteopontin expression was variable in CCRCCs and had no association withVHLgenetic status.Conclusion: As expression of these proposed pVHL targets can be achieved independently ofVHLmutation (and possibly by hypoxia alone), these data suggests that other pVHL targets may be more crucial in renal carcinogenesis.

scholarly journals Control of Angiogenesis via a VHL/miR-212/132 Axis

Cells ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 1017 ◽  
Author(s):  
Zhiyong Lei ◽  
Timothy D. Klasson ◽  
Maarten M. Brandt ◽  
Glenn van de Hoek ◽  
Ive Logister ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Vascular Endothelial Cells ◽  
Suppressor Gene ◽  
Protein Product ◽  
Cell Renal Cell Carcinoma ◽  
Von Hippel Lindau ◽  
Clinical Interest ◽  
Biallelic Mutations

A common feature of tumorigenesis is the upregulation of angiogenesis pathways in order to supply nutrients via the blood for the growing tumor. Understanding how cells promote angiogenesis and how to control these processes pharmaceutically are of great clinical interest. Clear cell renal cell carcinoma (ccRCC) is the most common form of sporadic and inherited kidney cancer which is associated with excess neovascularization. ccRCC is highly associated with biallelic mutations in the von Hippel–Lindau (VHL) tumor suppressor gene. Although upregulation of the miR-212/132 family and disturbed VHL signaling have both been linked with angiogenesis, no evidence of a possible connection between the two has yet been made. We show that miRNA-212/132 levels are increased after loss of functional pVHL, the protein product of the VHL gene, in vivo and in vitro. Furthermore, we show that blocking miRNA-212/132 with anti-miRs can significantly alleviate the excessive vascular branching phenotype characteristic of vhl−/− mutant zebrafish. Moreover, using human umbilical vascular endothelial cells (HUVECs) and an endothelial cell/pericyte coculture system, we observed that VHL knockdown promotes endothelial cells neovascularization capacity in vitro, an effect which can be inhibited by anti-miR-212/132 treatment. Taken together, our results demonstrate an important role for miRNA-212/132 in angiogenesis induced by loss of VHL. Intriguingly, this also presents a possibility for the pharmaceutical manipulation of angiogenesis by modulating levels of MiR212/132.

scholarly journals Playing Tag with HIF: The VHL Story

2002 ◽  
Vol 2 (3) ◽  
pp. 131-135 ◽  
Author(s):  
Sherri K. Leung ◽  
Michael Ohh
Keyword(s):  
Ubiquitin Ligase ◽  
Molecular Mechanisms ◽  
Target Genes ◽  
Hypoxia Inducible Factor ◽  
E3 Ubiquitin Ligase ◽  
Suppressor Gene ◽  
Tumour Suppressor Gene ◽  
Matrix Assembly ◽  
Von Hippel Lindau ◽  
Ubiquitin Ligase Complex

Inactivation of the von Hippel-Lindau (VHL) tumour suppressor gene product pVHL is the cause of inherited VHL disease and is associated with sporadic kidney cancer. pVHL is found in a multiprotein complex with elongins B/C, Cul2, and Rbx1 forming an E3 ubiquitin ligase complex called VEC. This modular enzyme targets theαsubunits of hypoxia-inducible factor (HIF) for ubiquitin-mediated destruction. Consequently, tumour cells lacking functional pVHL overproduce the products of HIF-target genes such as vascular endothelial growth factor (VEGF), which promotes angiogenesis. This likely accounts for the hypervascular nature of VHL-associated neoplasms. Although pVHL has been linked to the cell-cycle, differentiation, and the regulation of extracellular matrix assembly, microenvironment pH, and tissue invasiveness, this review will focus on the recent insights into the molecular mechanisms governing the E3 ubiquitin ligase function of VEC.

scholarly journals New HIF2α inhibitors: potential implications as therapeutics for advanced pheochromocytomas and paragangliomas

2017 ◽  
Vol 24 (9) ◽  
pp. C9-C19 ◽  
Author(s):  
Rodrigo Almeida Toledo
Keyword(s):  
Amino Acids ◽  
Human Cancer ◽  
Hypoxia Inducible Factor ◽  
Fumarate Hydratase ◽  
Elongation Factor ◽  
Cell Renal Cell Carcinoma ◽  
Von Hippel Lindau ◽  
Therapeutic Opportunity

Two recent independent studies published in Nature show robust responses of clear cell renal cell carcinoma (ccRCC) cell lines, preclinical ccRCC xenograft models and, remarkably, a patient with progressive ccRCC despite receiving multiple lines of treatment, to the long-awaited, recently developed inhibitors of hypoxia-inducible factor 2-alpha (HIF2α). This commentary published in Endocrine-Related Cancer is based on the recognition of similar molecular drivers in ccRCC and the endocrine neoplasias pheochromocytomas and paragangliomas (PPGLs), ultimately leading to stabilization of HIFs. HIF-stabilizing mutations have been detected in the von Hippel–Lindau (VHL) gene, as well as in other genes, such as succinate dehydrogenase (SDHx), fumarate hydratase (FH) and transcription elongation factor B subunit 1 (TCEB1), as well as the gene that encodes HIF2α itself: EPAS1HIF2α. Importantly, the recent discovery of EPAS1 mutations in PPGLs and the results of comprehensive in vitro and in vivo studies revealing their oncogenic roles characterized a hitherto unknown direct mechanism of HIF2α activation in human cancer. The now available therapeutic opportunity to successfully inhibit HIF2α pharmacologically with PT2385 and PT2399 will certainly spearhead a series of investigations in several types of cancers, including patients with SDHB-related metastatic PPGL for whom limited therapeutic options are currently available. Future studies will determine the efficacy of these promising drugs against the hotspot EPAS1 mutations affecting HIF2α amino acids 529–532 (in PPGLs) and amino acids 533–540 (in erythrocytosis type 4), as well as against HIF2α protein activated by VHL, SDHx and FH mutations in PPGL-derived chromatin cells.

Molecular pathology of von Hippel–Lindau disease and the VHL tumour suppressor gene

2001 ◽  
Vol 3 (8) ◽  
pp. 1-27 ◽  
Author(s):  
Frances M. Richards
Keyword(s):  
Hypoxia Inducible Factor ◽  
Suppressor Gene ◽  
Tumour Suppressor Gene ◽  
Tumour Suppressor ◽  
Missense Mutations ◽  
Cancer Syndrome ◽  
Inherited Cancer ◽  
Von Hippel Lindau ◽  
Adrenal Chromaffin ◽  
Vhl Disease

von Hippel–Lindau (VHL) disease is a dominantly inherited cancer syndrome characterised by predisposition to multiple tumours of the eyes and central nervous system (haemangioblastomas), kidneys (renal cell carcinoma; RCC), adrenal chromaffin cells (phaeochromocytoma), and other organs. The VHL gene was isolated in 1993 and mutations or deletions in the VHL gene have been identified in the germline of nearly all tested individuals with VHL disease. Genotype–phenotype correlations have been observed: individuals with missense mutations are more likely to develop phaeochromocytoma than those with deletions or protein-truncating mutations are, and specific missense mutations at certain codons might not predispose to RCC. In accordance with its role as a tumour suppressor gene, the normal allele of the VHL gene is deleted, mutated or silenced by promoter methylation in the tumours from VHL patients, and in a large proportion of sporadic tumours of the same histological types as observed in VHL disease. Thus, the VHL gene is of major importance in the development of RCC in the general population. Recent advances in understanding the structure and function of the VHL protein (pVHL) have revealed insights into the different phenotypes, with indications that some retention of function might be required for predisposition to phaeochromocytoma. pVHL interacts with many cellular proteins, mainly via one of two protein-binding domains (α and β). The best-characterised interaction is that of pVHL with elongin C, which forms a complex with elongin B and Cullin 2 proteins. This complex has E3 ubiquitin ligase activity and promotes ubiquitin-mediated proteasomal degradation of the hypoxia-inducible factor 1α (HIF-1α) transcription factor under normal oxygen (normoxic) conditions. Loss of pVHL function leads to stabilisation of HIF-1 and expression under normoxic conditions of hypoxia-inducible genes including vascular endothelial growth factor (VEGF), which might explain the hypervascular phenotype of VHL tumours. Several other genes implicated in intra- and intercellular signalling and control of tumour growth are overexpressed in the absence of pVHL, but it is not yet clear which features of pVHL function are most significant for tumour suppression in different tissues. Further advances in understanding pVHL function might eventually enable development of specific therapies for prevention or treatment of VHL tumours and RCC.

scholarly journals CTCF Expression Is Essential for Somatic Cell Viability and Protection against Cancer

2018 ◽  
Author(s):  
Charles G. Bailey ◽  
Cynthia Metierre ◽  
Julie Feng ◽  
Kinsha Baidya ◽  
Galina N. Filippova ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Somatic Cells ◽  
Suppressor Gene ◽  
Genetic Alterations ◽  
Tumour Suppressor Gene ◽  
Tumour Suppressor ◽  
Tumour Suppressor Genes ◽  
Absolute Requirement ◽  
The Impact

CCCTC-binding factor (CTCF) is a conserved transcription factor that performs diverse roles in transcriptional regulation and chromatin architecture. Cancer genome sequencing reveals diverse acquired mutations in CTCF, which we have shown, functions as a tumour suppressor gene. While CTCF is essential for embryonic development, little is known of its absolute requirement in somatic cells and the consequences of CTCF haploinsufficiency. We examined the consequences of CTCF depletion in immortalised human and mouse cells using shRNA knockdown and CRISPR/Cas9 genome editing and examined the growth and development of heterozygous Ctcf (Ctcf+/-) mice. We also analysed the impact of CTCF haploinsufficiency by examining gene expression changes in CTCF-altered endometrial carcinoma. Knockdown and CRISPR/Cas9-mediated editing of CTCF reduced the cellular growth and colony-forming ability of K562 cells. CTCF knockdown also induced cell cycle arrest and a pro-survival response to apoptotic insult. However, in p53 shRNA-immortalised Ctcf+/- MEFs we observed the opposite: increased cellular proliferation, colony formation, cell cycle progression and decreased survival after apoptotic insult compared to wild type MEFs. CRISPR/Cas9-mediated targeting in Ctcf+/- MEFs revealed a predominance of in-frame microdeletions in Ctcf in surviving clones, however protein expression could not be ablated. Examination of CTCF mutations in endometrial cancers showed locus-specific alterations in gene expression due to CTCF haploinsufficiency, in concert with downregulation of tumour suppressor genes and upregulation of estrogen-responsive genes. Depletion of CTCF expression imparts a dramatic negative effect on normal cell function. However, CTCF haploinsufficiency can have growth-promoting effects consistent with known cancer hallmarks in the presence of additional genetic hits. Our results confirm the absolute requirement for CTCF expression in somatic cells and provide definitive evidence of CTCF’s role as a haploinsufficient tumour suppressor gene. CTCF genetic alterations in endometrial cancer indicate that gene dysregulation is a likely consequence of CTCF loss, contributing to, but not solely driving cancer growth.

scholarly journals CTCF Expression is Essential for Somatic Cell Viability and Protection Against Cancer

2018 ◽  
Vol 19 (12) ◽  
pp. 3832 ◽  
Author(s):  
Charles Bailey ◽  
Cynthia Metierre ◽  
Yue Feng ◽  
Kinsha Baidya ◽  
Galina Filippova ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Somatic Cells ◽  
Suppressor Gene ◽  
Genetic Alterations ◽  
Tumour Suppressor Gene ◽  
Tumour Suppressor ◽  
Tumour Suppressor Genes ◽  
Absolute Requirement ◽  
The Impact

CCCTC-binding factor (CTCF) is a conserved transcription factor that performs diverse roles in transcriptional regulation and chromatin architecture. Cancer genome sequencing reveals diverse acquired mutations in CTCF, which we have shown functions as a tumour suppressor gene. While CTCF is essential for embryonic development, little is known of its absolute requirement in somatic cells and the consequences of CTCF haploinsufficiency. We examined the consequences of CTCF depletion in immortalised human and mouse cells using shRNA knockdown and CRISPR/Cas9 genome editing as well as examined the growth and development of heterozygous Ctcf (Ctcf+/−) mice. We also analysed the impact of CTCF haploinsufficiency by examining gene expression changes in CTCF-altered endometrial carcinoma. Knockdown and CRISPR/Cas9-mediated editing of CTCF reduced the cellular growth and colony-forming ability of K562 cells. CTCF knockdown also induced cell cycle arrest and a pro-survival response to apoptotic insult. However, in p53 shRNA-immortalised Ctcf+/− MEFs we observed the opposite: increased cellular proliferation, colony formation, cell cycle progression, and decreased survival after apoptotic insult compared to wild-type MEFs. CRISPR/Cas9-mediated targeting in Ctcf+/− MEFs revealed a predominance of in-frame microdeletions in Ctcf in surviving clones, however protein expression could not be ablated. Examination of CTCF mutations in endometrial cancers showed locus-specific alterations in gene expression due to CTCF haploinsufficiency, in concert with downregulation of tumour suppressor genes and upregulation of estrogen-responsive genes. Depletion of CTCF expression imparts a dramatic negative effect on normal cell function. However, CTCF haploinsufficiency can have growth-promoting effects consistent with known cancer hallmarks in the presence of additional genetic hits. Our results confirm the absolute requirement for CTCF expression in somatic cells and provide definitive evidence of CTCF’s role as a haploinsufficient tumour suppressor gene. CTCF genetic alterations in endometrial cancer indicate that gene dysregulation is a likely consequence of CTCF loss, contributing to, but not solely driving cancer growth.

Role of the VHL (von Hippel–Lindau) gene in renal cancer: a multifunctional tumour suppressor

2008 ◽  
Vol 36 (3) ◽  
pp. 472-478 ◽  
Author(s):  
Michelle J. Nyhan ◽  
Gerald C. O'Sullivan ◽  
Sharon L. McKenna
Keyword(s):  
Target Genes ◽  
Hypoxia Inducible Factor ◽  
Suppressor Gene ◽  
Tumour Suppressor Gene ◽  
Tumour Suppressor ◽  
Current Evidence ◽  
Von Hippel Lindau ◽  
Ubiquitin Ligase Complex ◽  
Protein Functions ◽  
Factor Α

The VHL (von Hippel–Lindau) tumour-suppressor gene is inactivated in VHL disease and in sporadic cases of CCRCC [clear-cell RCC (renal cell carcinoma)]. pVHL (VHL protein) functions as part of an E3 ubiquitin ligase complex that targets proteins for proteasomal degradation. The best-characterized substrate is HIF-α (hypoxia-inducible factor-α). Loss of pVHL and subsequent up-regulation of HIF target genes has been attributed to the highly vascular nature of these neoplasms. However, pVHL does not just function as the executioner of HIF-α. Additional functions of pVHL that may be important in preventing CCRCC tumorigenesis have been identified, including primary cilium maintenance, assembly of the extracellular matrix and roles in the stabilization of p53 and Jade-1 (gene for apoptosis and differentiation in epithelia). Current evidence indicates that pVHL probably requires additional co-operating signalling pathways for CCRCC initiation and tumorigenesis.

scholarly journals Regulation of Renal Epithelial Tight Junctions by the von Hippel-Lindau Tumor Suppressor Gene Involves Occludin and Claudin 1 and Is Independent of E-Cadherin

2009 ◽  
Vol 20 (3) ◽  
pp. 1089-1101 ◽  
Author(s):  
Sarah K. Harten ◽  
Deepa Shukla ◽  
Ravi Barod ◽  
Alexander Hergovich ◽  
Maria S. Balda ◽  
...  
Keyword(s):  
Tumor Suppressor ◽  
Hypoxia Inducible Factor ◽  
Adherens Junction ◽  
Suppressor Gene ◽  
Loss Of Function ◽  
Down Regulation ◽  
Cell Renal Cell Carcinoma ◽  
E Cadherin

Epithelial-to-mesenchymal transitions (EMT) are important in renal development, fibrosis, and cancer. Loss of function of the tumor suppressor VHL leads to many features of EMT, and it has been hypothesized that the pivotal mediator is down-regulation of the adherens junction (AJ) protein E-cadherin. Here we show that VHL loss-of-function also has striking effects on the expression of the tight junction (TJ) components occludin and claudin 1 in vitro in VHL-defective clear cell renal cell carcinoma (CCRCC) cells and in vivo in VHL-defective sporadic CCRCCs (compared with normal kidney). Occludin is also down-regulated in premalignant foci in kidneys from patients with germline VHL mutations, consistent with a contribution to CCRCC initiation. Reexpression of E-cadherin was sufficient to restore AJ but not TJ assembly, indicating that the TJ defect is independent of E-cadherin down-regulation. Additional experiments show that activation of hypoxia inducible factor (HIF) contributes to both TJ and AJ abnormalities, thus the VHL/HIF pathway contributes to multiple aspects of the EMT phenotype that are not interdependent. Despite the independent nature of the defects, we show that treatment with the histone deacetylase inhibitor sodium butyrate, which suppresses HIF activation, provides a method for reversing EMT in the context of VHL inactivation.

scholarly journals A small molecule HIF-1α stabilizer that accelerates diabetic wound healing

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Guodong Li ◽  
Chung-Nga Ko ◽  
Dan Li ◽  
Chao Yang ◽  
Wanhe Wang ◽  
...  
Keyword(s):  
Wound Healing ◽  
Small Molecule ◽  
Hypoxia Inducible Factor ◽  
Diabetic Patients ◽  
Diabetic Mice ◽  
Impaired Wound Healing ◽  
Von Hippel Lindau ◽  
Design And Synthesis

AbstractImpaired wound healing and ulcer complications are a leading cause of death in diabetic patients. In this study, we report the design and synthesis of a cyclometalated iridium(III) metal complex 1a as a stabilizer of hypoxia-inducible factor-1α (HIF-1α). In vitro biophysical and cellular analyses demonstrate that this compound binds to Von Hippel-Lindau (VHL) and inhibits the VHL–HIF-1α interaction. Furthermore, the compound accumulates HIF-1α levels in cellulo and activates HIF-1α mediated gene expression, including VEGF, GLUT1, and EPO. In in vivo mouse models, the compound significantly accelerates wound closure in both normal and diabetic mice, with a greater effect being observed in the diabetic group. We also demonstrate that HIF-1α driven genes related to wound healing (i.e. HSP-90, VEGFR-1, SDF-1, SCF, and Tie-2) are increased in the wound tissue of 1a-treated diabetic mice (including, db/db, HFD/STZ and STZ models). Our study demonstrates a small molecule stabilizer of HIF-1α as a promising therapeutic agent for wound healing, and, more importantly, validates the feasibility of treating diabetic wounds by blocking the VHL and HIF-1α interaction.

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