Cellular and molecular characterization of the altered metabolism in RCC
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ABSTRACT: RCC cells (786-O) were transfected with VHL. The parental cell line should be compared to the transfectant (+ VHL) under nomoxia as well as under hypoxia conditions. We want to distinct the VHL-mediated gene expression from the hypoxia-mediated and study the influence of both on the cellular metabolism. RNA of VHL-negative 786-O RCC cell line and VHL-transfectants incubated during normoxia and hypoxia conditions were analysed by cDNA microarray.
Project description:RCC cells (786-O) were transfected with VHL. The parental cell line should be compared to the transfectant (+ VHL) under nomoxia as well as under hypoxia conditions. We want to distinct the VHL-mediated gene expression from the hypoxia-mediated and study the influence of both on the cellular metabolism.
Project description:Changes in mRNA abundance upon HIF activation and/or hypoxia in VHL-defective kidney cancer cell were analysed. Sequencing of the 5′ ends of mRNAs (5′ end-Seq) was applied to VHL-defective kidney cancer cell lines with or without reintroduction of VHL and/or with hypoxic incubation (1% O2 for 24h) to analyse the abundance of mRNAs resolved by their transcription start sites. In addition, the contribution of HIF pathway was confirmed using 786-O cells in which HIF1B was inactivated.
Project description:The aim of the present study was to investigate the potential role of HIF-2a in regulating RCC susceptibility to natural killer (NK) cell-mediated killing. We demonstrated that the RCC cell line 786-O with mutated VHL was resistant to NK-mediated lysis as compared to the VHL corrected cell line (WT7). This resistance was independent of immunological synapse formation and NK ligand expression but was found to be reliant on HIF-2a stabilization in 786-0 cells. In order to elucidate the molecular basis of HIF-2a-induced impairment of NK-mediated killing, we performed global gene analysis using DNA microarray. Three candidate genes (ANGPTL4, ADM and ITPR1) were selected on the basis of their fold change and their involvement in cell death and survival. SiRNA targeting of these genes revealed that only ITPR1 silencing resulted in a significant increase of 786-O susceptibility to NK-mediated lysis. Using gene silencing of HIF2-a and chromatin immunoprecipitation assay, we showed for the first time that ITPR1 was a direct novel target of HIF2-a. Notably, a strong and significant correlation was found between ITPR1and HIF2-a staining in RCC patients. Transcriptional profiling of ITPR1silenced RCC cells indicated that several important genes involved in cell survival and apoptosis were differentially regulated. Using ITPR1 silenced Renca cells, we further found that ITPR1 was involved in the control of tumor progression. Moreover ITPR1 targeting combined with NK depletion significantly enhanced tumor growth as compared to ITPR1 knocked down Renca xenografts. Our data provide insights into the link between HIF-2a, ITPR1-related pathway and natural immunity and suggest a role of the HIF2/ITPR1 axis in regulating RCC cell survival.
Project description:The human renal cancer cell line 786-0 was transfected with 3 vectors allowing the doxycycline-inducible expression of 1) the full length wild type sequence of VHL: 786-0 VHL WT, VHL+/+, 2) the R167Q mutant : 786-0 R167Q, VHL mutated, 3) the empty vector : 786-0 EV, VHL-/-. The aim of the study was to examine whether the VHL-R167Q mutation, which is associated with a high risk of developping clear cell renal carcinomas, could impact the plasticity of renal carcinoma cells.
Project description:Changes in translational efficiency of mRNAs consequent on alteration of HIF and/or mTOR pathway activity in VHL-defective kidney cancer cell were analysed. High-resolution polysome profiling followed by sequencing of the 5′ ends of mRNAs (HP5) was used to measure translational efficiency of mRNAs resolved by their transcription start sites. HP5 was applied to VHL-defective kidney cancer cell lines with or without VHL reintroduction and/or mTOR inhibition with Torin 1 treatment. In addition, the contribution of HIF2A/EIF4E2 pathway was assessed using 786-O cells in which EIF4E2 was inactivated.
Project description:Renal hypoxia is widespread in acute kidney injury (AKI) of various aetiologies. Hypoxia adaptation, conferred through the hypoxia-inducible factor (HIF), appears to be insufficient. Here we show that HIF activation in renal tubules through Pax8-rtTA-based inducible knockout of von Hippel-Lindau protein (VHL-KO) protects from rhabdomyolysis-induced AKI. In this model, histological observations indicate that injury mainly affects proximal convoluted tubules, with 5% necrosis at d1 and 40% necrosis at d2. HIF-1alpha up-regulation in distal tubules reflects renal hypoxia. However, lack of HIF in proximal tubules suggests insufficient adaptation by HIF. AKI in VHL-KO mice leads to prominent HIF activation in all nephron segments, as well as to reduced serum creatinine, serum urea, tubular necrosis, and apoptosis marker caspase-3 protein. At d1 after rhabdomyolysis, when tubular injury is potentially reversible, HIF mediated protection in AKI is associated with activated glycolysis, cellular glucose uptake and utilization, autophagy, vasodilation, and proton removal as demonstrated by qPCR, pathway enrichment analysis and immunohistochemistry. Together, our data provide evidence for a HIF-orchestrated multi-level shift towards glycolysis as a major mechanism for protection against acute tubular injury. All experiments were carried out in transgenic mice in which selective renal tubular VHL knockout (VHL-KO) was inducible by doxycycline (Reference: Mathia S, Paliege A, Koesters R, Peters H, Neumayer HH, Bachmann S, Rosenberger C. Action of hypoxia-inducible factor in liver and kidney from mice with Pax8-rtTA-based deletion of von Hippel-Lindau protein. Acta Physiol (Oxf). 2013; 207(3):565-76.). Four groups of animals were used: 1) controls: untreated mice; 2) VHL-KO: injected with doxycycline (0.1 mg per 10 g body weight SC), 4 days prior to sacrifice; 3) AKI: rhabdomyolysis; 4) VHL-KO/AKI: doxycycline plus rhabdomyolysis. To induce AKI, 50% glycerol (0.05 ml per 10 g body weight) was injected IM into the left hind limb under isoflurane narcosis. Drinking water was withdrawn between 20 h prior and 24 h after glycerol injection.
Project description:VHL is a tumor suppressor gene involved in the oxygen-sensing pathway whose germline mutations predispose to distinct phenotypes. Heterozygous mutations predispose to von Hippel-Lindau disease characterized by the development of multiple tumors (including hemangioblastomas, renal cell carcinomas and pheochromocytomas)1-3. More recently, a specific VHL-R200W mutation was shown to be responsible for Chuvash Polycythemia in homozygous carriers whereas heterozygous individuals have no clinical manifestation4. We report here a family carrying, on the same allele, VHL mutations characteristics of the two types of disease (a Chuvash polycythemia-R200W mutation and a von Hippel-Lindau disease-R161Q mutation). Genotyping, modeling analysis and functional studies, including transcriptomic profile of the distinct mutants validated for the first time on direct HIF target genes, show a gradual capacity of the VHL mutants to regulate the hypoxia responsive pathway that correlate with the severity of the developed phenotype. Our study provide original results that illuminate genotype/phenotype correlations in von Hippel-Lindau disease.
Project description:While early stages of clear cell renal cell carcinoma (ccRCC) are curable, survival outcome for metastatic ccRCC remains poor. The purpose of the current study was to apply a new individualized bioinformatics analysis (IBA) strategy to these transcriptome data in conjunction with Gene Set Enrichment Analysis of the Connectivity Map (C-MAP) database to identify and reposition FDA-approved drugs for anti-cancer therapy. We demonstrated that one of the drugs predicted to revert the RCC gene signature towards normal kidney, pentamidine, is effective against RCC cells in culture and in a RCC xenograft model. Most importantly, pentamidine slows tumor growth in the 786-O human ccRCC xenograft mouse model. To determine which genes are regulated by pentamidine in a human RCC cell line, 786-O, we treated these cells with pentamidine and performed transcriptional profiling analysis. We used microarrays to determine the set of genes regulated by pentamidine in 786-O renal cell cancer cells. Total RNA was isolated from 786-O cells treated with 25 μM pentamidine or vehicle control (DMSO) for 6 hours and hybridized to Affymetrix microarrays.
Project description:Altered metabolism is an important part of malignant transformation of tumor cells. Oncogenic transformation may reprogram tumor metabolism and render tumor cells addicted to extracellular nutrients. Such nutrient addictions associated with oncogenic mutations may offer therapeutic opportunities; however, it remains difficult to predict these nutrient addictions. Here, we performed a nutrigenetic screen to determine the phenotypes of isogenic pairs of clear-cell renal cancer cells (ccRCC) with or without VHL upon the deprivation of individual amino acids. We identified that cystine deprivation triggered rapid programmed necrosis in VHL-deficient RCC, but not in their VHL-restored counterparts. Similar cystine addiction was also observed in VHL-deficient primary RCC tumors cells. Blockage of cystine uptake significantly delayed xenograft growth of ccRCC. Importantly, cystine deprivation triggered similar metabolic changes regardless of VHL status. Therefore, metabolic differences due to cystine deprivation are not different enough to readily explain the distinct fate of life vs. death in VHL-deficient and restored cell.. Instead, we found that increased levels of TNFα associated with VHL loss in the VHL-deficient RCC force them to rely on intact RIPK1 to inhibit apoptosis. However, this pre-existing elevated TNFα in the VHL-deficient ccRCC renders these cells susceptible to the necrosis signaling triggered by cystine deprivation. In addition, we identified that cystine-deprived necrosis in VHL-deficient RCC depends on reciprocal amplification of the Src-p38-Noxa signaling and TNFα-RIP1/3-MLKL necrosis pathways that culminate in MLKL oligomerization and programmed necrosis. Together, our data reveal that the contextual cystine-addictions in VHL-deficient ccRCC is dependent on activating pre-existing oncogenic pathways to trigger programmed necrosis. RNA was extracted by RNAeasy kits (Qiagen) from the RCC4 Vec and VHL-reconstituted cells which were exposed to the control full DMEM or cystine deprived DMEM media for 6 hours (three replicates in each condition).
Project description:Renal cell carcinoma (RCC) accounts for around 2-3% of all adult neoplasms and its incidence is increasing. RCC is largely resistant to standard cancer treatment regimens including chemotherapy and radiation therapy, whilst immunotherapy modestly provides benefit to only a small subset of patients. As a result, prognosis for RCC patients with advanced disease is very poor, with a 5-year survival rate of less than 10%. An early event in the development of familial and up to 90% of sporadic RCC is the loss and/or mutation/methylation of the von Hippel-Lindau (VHL) tumour suppressor gene. The tumor suppressor role of VHL relies primarily on its ability to target members of the hypoxia-inducible factors (HIF) for proteosomal degradation, however it has also been implicated in other biological processes linked to oncogenesis, such as the extracellular matrix assembly and the regulation of actin cytoskeleton, that are less clearly defined. Targeting the VHL/HIF pathway may dramatically improve RCC treatment, as demonstrated by an increasing number of novel agents that have shown promising activity in recent clinical trials6. Identification of other possible proteins regulated by VHL that may be involved in tumour suppression will improve our understanding of RCC pathobiology and also provide novel disease biomarkers or potential targets. A number of our studies have identified changes in glycosylation in RCC, at least some of which appear to alter as a result of changes in the VHL gene. Lectin binding immunohistochemistry shows altered reactivity with a number of lectins in the malignant tissue compared with the normal tissue. Comparison of plasma membrane protein enriched fractions from human RCC cells stably transfected with control vector or with wild type VHL led to the identification of VHL-associated changes in the forms of several plasma membrane proteins which we beelive to be due to differential glycosylation. For one of these we have now shown that it is differentially O-glycosylated and this has been confimed in cell lysates and patient tissue by Western blotting. A parallel approach using 2D-PAGE analysis of RCC cell line conditioned medium (CM) has also identified a tumour-specific glycoform of a secretory protein that appears to undergo differential N-glycosylation in RCC and this has been confirmed in analysis of some matched primary tumour/normal pairs. These findings are potentially very interesting, as these proteins could serve as prognostic or diagnostic markers, or even as targets for improving RCC therapy. We are therefore keen to explore the underlying mechanism of differential glycosylation that may be associated to VHL dependent gene expression. As there are an immense number of enzymes involved in the conjugation of N- and particularly O-glycans to proteins, the glyco-microarray is an ideal tool to elucidate this further. For chip analyses we have three cell lines generated from human RCC cells (RCC4, 786-0 and UMRC2) that have been stably transfected with control vector or with wild type VHL i.e. 6 cell lines in total. Whole RNA was extracted from each cell line in 3 replicates per line.