Unknown,Transcriptomics,Genomics,Proteomics

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VHL Status Influences Phenotype of Liver Cancers Arising from PTEN Loss

ABSTRACT: Background: PTEN loss contributes to the development of many cancers and is associated with both hepatocellular carcinoma and cholangiocarcinoma. The pathogenesis of these malignancies is unclear, but they are speculated to arise from common cellular origins. We explored the influence of secondary effects, like hypoxia signaling, through co-deletion of Pten and Vhl in a murine model.Methods: We used a CreER-linked keratin 18 mouse model to conditionally delete Pten, Vhl or both, evaluating the resultant tumors by histology and gene expression microarray. A cohort of human cholangiocarcinoma samples was evaluated for relationships between HIF-1a expression and clinical outcomes.Results: Both Pten deletion genotypes developed liver tumors, but with differing phenotypes. Pten deletion alone led to large, invasive tumors with widespread hepatosteatosis. Co-deletion of Pten and Vhl resulted in low tumor burden and reduced steatosis. Microarray analysis divided mouse tumors’ respective genotypes by gene expression. This gene expression profile grouped a human tumor cohort according to histologic type with the Pten deletion signature aligning with hepatocellular carcinoma, whereas the Pten; Vhl deletion signature associated with cholangiocarcinomas. In a human cholangiocarcinoma cohort, we observed correlation between HIF-1a expression and overall survival.Conclusions: Pten deletion leads to tumor formation and steatosis in mouse livers. Co-deletion of Vhl and Pten resulted in lower tumor burden with gene expression profiling suggesting a switch from hepatocellular expression features to an expression profile more consistent with cholangiocarinoma. A possible relation between HIF-1a expression and increased overall survival in human cholangiocarcinoma suggests that hypoxia signaling influences tumor phenotype. reference x sample

ORGANISM(S): Mus musculus

SUBMITTER: Kimryn Rathmell

PROVIDER: E-GEOD-55874 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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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:Gene expression data from VHL teratomas comparing genes differentially expressed based on apoptotic response to tumor microenvironment. Abstract BACKGROUND: The risk relevance of the P81S von Hippel-Lindau (VHL) gene hotspot mutation identified in clear cell renal cell carcinoma from individuals exposed occupationally to trichloroethylene (TCE) is not known. VHL mutations in hereditary VHL syndrome strongly correlate with phenotypic associations, but specific sporadic mutations in VHL that uniquely alter its protein function may provide a selective growth advantage for somatic cells harboring these mutations. METHODS: VHL deficient (Vhl -/- ) mouse embryonic stem cells were generated that stably express wild-type, P81S, or R167Q human VHL protein. Under hypoxic conditions, cell lines were examined for hypoxia-inducible transcription factor family (HIF) stabilization and E3-ubiquitin ligase complex interactions. In vivo, teratomas were examined for tumor size, proliferation, apoptosis, and immunohistochemistry and subjected to gene expression analysis. Wild-type, R167Q, and P81S VHL-expressing teratomas were also exposed to 5 Gy ionizing radiation to quantify apoptotic response. Proliferation and apoptosis and teratoma growth were analyzed by either Student t test or analysis of variance with Bonferroni correction. All statistical tests were two-sided. RESULTS: The P81S VHL mutation produces deregulation of HIF factors in cell culture but exhibits a growth advantage in the tumor microenvironment, in part because of suppression of apoptosis (P81S mean = 0.9%, 95% confidence interval = 0.6 to 1.2%; WT mean = 7.6%; 95% confidence interval = 6.4 to 8.8%; P < .001) coupled with sustained proliferation. Transcriptional analysis of P81S teratomas revealed the induction of metabolic pathways, antiapoptotic genes, and global suppression of key DNA damage response genes not observed in VHL wild-type or R167Q mutants. In vivo irradiation exposure showed that P81S mutant is resistant to ionizing radiation-induced apoptosis. CONCLUSIONS: The TCE-associated P81S VHL mutation can initiate a unique adaptive response required for selective tumor growth through pleiotropic effects on metabolic diversification, apoptosis suppression, and alteration of the DNA damage response. Three genotypes of VHL teratomas were examined: Three replicate wildtype VHL, Three replicate R167Q VHL, and Four replicate P81S VHL (representing two replicates of two different P81S clones)

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VHL Status Influences Phenotype of Liver Cancers Arising from PTEN Loss

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