A novel approach to tracing oncogenesis following von Hippel Lindau inactivation in mice

Thesis

Defining the early events following cancer mutation in cells of normal tissues is an enduring challenge in understanding the origins of cancer. In clear cell renal cell carcinoma (ccRCC) evolution, the inactivation of the ubiquitously-expressed von Hippel Lindau (VHL) tumour suppressor gene is a truncal event. However, VHL-associated oncogenesis is highly tissue-specific and can require years or decades between VHL inactivation and presentation of cancer. This raises unanswered questions as to the behaviour of VHL-null cells prior to neoplastic transformation and the contexts in which such transformation is supported.

To study this behaviour, I have developed the use of a novel reporter mouse model that couples conditional Vhl inactivation to the expression of a tdTomato reporter within a single allele. This allows Vhl-null cells to be visualised and assayed in their native context and be retrieved accurately from tissues for ex vivo analyses and single-cell RNA sequencing. I have employed the model to study the early and time-accumulated survival, proliferative, and transcriptomic phenotypes of Vhl-null cells in tissues that are or are not associated with VHL-driven cancer. I have also tested whether co-inactivation of Polybromo-1 (Pbrm1), the second most inactivated gene in ccRCC, affects these phenotypes of Vhl-null cells in the kidney and accelerates oncogenesis.

These investigations provide the first description of the heterogenous cellular and transcriptomic effects of Vhl inactivation in vivo with single-cell resolution. They 1) reveal that Vhl-null cells undergo cell-type specific elimination and time-restricted proliferation, 2) identify a novel class of renal proximal tubular cells as potential ccRCC cells-of-origin, and 3) suggest that Pbrm1 inactivation promotes oncogenesis only in specific contexts. This work suggests that early events in normal cells can shape the cell-type specificity of oncogenesis and provide a focus for mechanistic understanding.

Authors: Kurlekar, S

• DOI: 10.5287/ora-r1kkzkvak
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: mouse model; VHL; PBRM1; scRNA-seq; single-cell sequencing; lineage tracing; tumorigenesis; oncogenesis; renal cancer; ccRCC
• Subjects: Cell Biology; Nephrology; Histology; Genomics; Cancer Biology