Research Group GILES

Faculty of Medicine, University Medical Center Utrecht, Dept. of Medical Oncology
Contact: Dr. Rachel Giles
E-mail: r.giles@umcutrecht.nl
Website: http://www.umcutrecht.nl/subsite/oncology/Research-groups/Giles/

General research focus: Understanding kidney cancer

In families where a single mutated gene causes cancer, studying the specific mutations and the cellular signaling circuits disrupted by the mutant proteins are informative concerning the molecular basis for that type of cancer in general.

von Hippel-Lindau (VHL)
The von Hippel-Lindau (VHL) hereditary cancer syndrome is caused by inactivating mutations of the VHL gene, characterized by extensively vascularized tumors and cysts in several organs. Most of these patients develop kidney cancer. Intriguingly, the vast majority of kidney tumors occurring in the general public also have inactivating mutations in the VHL gene, suggesting that VHL protein is essential for maintaining kidney cell equilibrium. Functional analysis has revealed that the VHL gene product regulates the degradation of hypoxia inducible factor (HIF), an important activator of the genetic program triggered by low levels of oxygen. HIF activates target genes whose products play key roles in processes such as angiogenesis, metabolism and cell proliferation. In many cancer types, activated HIF promotes tumor growth. The absence of functional VHL, thus, artificially stabilizes HIF and induces a cellular response to perceived low-oxygen tension. Although HIF accumulation likely accounts for the extensive vascularization observed in VHL-related lesions, several lines of evidence point to additional function(s) of VHL. We are particularly interested in VHL with respect to the regulation of microtubule dynamics, including cell division, cell polarity and transport. Furthermore we examine how VHL regulates primary cilia in the sensing of luminal flow in kidney tubules.

Zebrafish VHL
The mouse Vhl knock-out dies as an early embryo due to placental defects, which has been of limited use to model either VHL disease or kidney cancer. In a collaboration with the Hubrecht Institute (Schulte-Merker group) we are generating a model for VHL using the tropical zebrafish (Danio rerio). The transparency of zebrafish embryos and the development outside of the mother allow processes to be followed in great detail and over long periods of time. Using a technique called TILLING, we have generated two different zebrafish lines carrying germline inactivating mutations of vhl. Vhl mutant fish mimic many key aspects of VHL disease, including excessive hematopoietic, kidney, and blood vessel tissue. HIF target genes are globally upregulated in vhl mutant fish, supporting the notion that these fish experience an artificial response to low oxygen even though they are in normal oxygen conditions. We hope to use this VHL model to understand the early events of kidney cancer and test novel therapies.

Techniques/Approaches
Confocal microscopy of cells and zebrafish; Fluorescent recovery after photobleaching (FRAP); Zebrafish as a tumor model; Hypoxia signaling assays; Tumor sectioning and immunohistochemistry; Functional assays of cilia (eg. Calcium flux assays under flow); 3D polarity/morphogenesis assays in collagen/matrigel; Lenitviral and retroviral transduction; Electron microscopy; Biochemistry(immunoprecipitation, IVTT, recombinant protein production); Generation of monoclonal antibodies; FACS; Cell cycle analyses; ELISA; Clinical statistics

For internships, please contact Dr. Susanne Lens, S.M.A.Lens_at_umcutrecht.nl

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