Renal cell cancer (RCC) is a heterogeneous disease consisting of different histologic types. Major advances have been accomplished during the last 15 years in our understanding of the genetic events ...that initiate RCC. These advances were greatly facilitated by meticulous clinical description and registration of patients with familial predisposition to RCC. The cloning of the susceptibility genes that underline familial predisposition to RCC has offered entry points into the signaling pathways that are also deregulated in sporadic RCC. Biochemical studies of these signaling pathways and target validation experiments have already culminated in the discovery and clinical application of small molecules with promising activity in RCC. In this article, we highlight the molecular genetic features of RCC that are more directly related to identification and validation of promising targets for molecular therapy.
Hypoxic and VHL-deficient cells use glutamine to generate citrate and lipids through reductive carboxylation (RC) of α-ketoglutarate. To gain insights into the role of HIF and the molecular ...mechanisms underlying RC, we took advantage of a panel of disease-associated VHL mutants and showed that HIF expression is necessary and sufficient for the induction of RC in human renal cell carcinoma (RCC) cells. HIF expression drastically reduced intracellular citrate levels. Feeding VHL-deficient RCC cells with acetate or citrate or knocking down PDK-1 and ACLY restored citrate levels and suppressed RC. These data suggest that HIF-induced low intracellular citrate levels promote the reductive flux by mass action to maintain lipogenesis. Using 1–13Cglutamine, we demonstrated in vivo RC activity in VHL-deficient tumors growing as xenografts in mice. Lastly, HIF rendered VHL-deficient cells sensitive to glutamine deprivation in vitro, and systemic administration of glutaminase inhibitors suppressed the growth of RCC cells as mice xenografts.
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► HIF is necessary and sufficient to induce reductive carboxylation in RCC cell lines ► HIF promotes the reductive carboxylation flux by reducing citrate levels ► HIF-expressing tumors display reductive carboxylation in vivo ► HIF renders RCC cells sensitive to glutaminase inhibition in vitro and in vivo
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.
This brief report focuses on the evaluation and diagnosis of clinically localized renal masses in children and adults with Von Hippel–Lindau (VHL) disease. Counseling considerations pertinent to the ...urologists, medical oncologists, and multidisciplinary teams involved in the care of these patients are addressed. As practice patterns regarding the evaluation and management of VHL tumors can vary considerably, this report aims to provide guidance on some of the controversies associated with the diagnostic evaluation and initial management of localized renal masses in VHL patients.
Germline mutations in the Folliculin (FLCN) tumour suppressor gene result in fibrofolliculomas, lung cysts and renal cancers, but the precise mechanisms of tumour suppression by FLCN remain elusive. ...Here we identify Rab7A, a small GTPase important for endocytic trafficking, as a novel FLCN interacting protein and demonstrate that FLCN acts as a Rab7A GTPase-activating protein. FLCN
cells display slower trafficking of epidermal growth factor receptors (EGFR) from early to late endosomes and enhanced activation of EGFR signalling upon ligand stimulation. Reintroduction of wild-type FLCN, but not tumour-associated FLCN mutants, suppresses EGFR signalling in a Rab7A-dependent manner. EGFR signalling is elevated in FLCN
tumours and the EGFR inhibitor afatinib suppresses the growth of human FLCN
cells as tumour xenografts. The functional interaction between FLCN and Rab7A appears conserved across species. Our work highlights a mechanism explaining, at least in part, the tumour suppressor function of FLCN.
Loss of RBF1 changes glutamine catabolism Nicolay, Brandon N; Gameiro, Paulo A; Tschöp, Katrin ...
Genes & development,
01/2013, Letnik:
27, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Inactivation of the retinoblastoma tumor suppressor (pRB) alters the expression of a myriad of genes. To understand the altered cellular environment that these changes create, we took advantage of ...the Drosophila model system and used targeted liquid chromatography tandem mass spectrometry (LC-MS/MS) to profile the metabolic changes that occur when RBF1, the fly ortholog of pRB, is removed. We show that RBF1-depleted tissues and larvae are sensitive to fasting. Depletion of RBF1 causes major changes in nucleotide synthesis and glutathione metabolism. Under fasting conditions, these changes interconnect, and the increased replication demand of RBF1-depleted larvae is associated with the depletion of glutathione pools. In vivo (13)C isotopic tracer analysis shows that RBF1-depleted larvae increase the flux of glutamine toward glutathione synthesis, presumably to minimize oxidative stress. Concordantly, H(2)O(2) preferentially promoted apoptosis in RBF1-depleted tissues, and the sensitivity of RBF1-depleted animals to fasting was specifically suppressed by either a glutamine supplement or the antioxidant N-acetyl-cysteine. Effects of pRB activation/inactivation on glutamine catabolism were also detected in human cell lines. These results show that the inactivation of RB proteins causes metabolic reprogramming and that these consequences of RBF/RB function are present in both flies and human cell lines.
The von Hippel-Lindau tumor suppressor protein (pVHL) is a substrate receptor for the mammalian SCF-2 E3 ubiquitin ligase complex that targets several substrates for ubiquitination and proteasomal ...degradation. Among these targets are the alpha-regulatory subunits of the hypoxia-inducible factor (HIF). VHL-/- cells constitutively overexpress hypoxia-inducible genes through both transcriptional and posttranscriptional mechanisms and form tumors when injected into nude mice. Reintroduction of pVHL into VHL-/- cell lines restores normal oxygen-dependent regulation of these genes and suppresses tumor formation in the mouse xenograft assay. We report here that short hairpin RNA-mediated inactivation of HIF phenocopies the effects of pVHL reintroduction with respect to decreased expression of hypoxia-inducible genes, decreased ability to promote vascular endothelial cell proliferation in vitro, and tumor growth suppression in vivo. In addition, HIF inactivation abrogated the cellular response to hypoxia, indicating that HIF is the only pVHL target required for this response. These data suggest that deregulation of hypoxia-inducible genes in VHL-/- cells can be attributed mainly to deregulation of HIF and validate HIF as a therapeutic anticancer drug target.
Clear cell renal cell carcinoma is the most prevalent of all reported kidney cancer cases, and currently there are no markers for early diagnosis. This has stimulated great research interest recently ...because early detection of the disease can significantly improve the low survival rate. Combining the proteome, glycoproteome, and N-glycome data from clear cell renal cell carcinoma plasma has the potential of identifying candidate markers for early diagnosis and prognosis and/or to monitor disease recurrence. Here, we report on the utilization of a multi-dimensional fractionation approach (12P-M-LAC) and LC–MS/MS to comprehensively investigate clear cell renal cell carcinoma plasma collected before (disease) and after (non-disease) curative nephrectomy (n = 40). Proteins detected in the subproteomes were investigated via label-free quantification. Protein abundance analysis revealed a number of low-level proteins with significant differential expression levels in disease samples, including HSPG2, CD146, ECM1, SELL, SYNE1, and VCAM1. Importantly, we observed a strong correlation between differentially expressed proteins and clinical status of the patient. Investigation of the glycoproteome returned 13 candidate glycoproteins with significant differential M-LAC column binding. Qualitative analysis indicated that 62% of selected candidate glycoproteins showed higher levels (upregulation) in M-LAC bound fraction of disease samples. This observation was further confirmed by released N-glycans data in which 53% of identified N-glycans were present at different levels in plasma in the disease vs non-disease samples. This striking result demonstrates the potential for significant protein glycosylation alterations in clear cell renal cell carcinoma cancer plasma. With future validation in a larger cohort, information derived from this study may lead to the development of clear cell renal cell carcinoma candidate biomarkers.
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