Epithelioid Haemangioendothelioma (EHE) is a rare sarcoma arising from vascular endothelial cells. EHE is unpredictable in nature, with disease ranging from indolent to highly aggressive. Recent studies have found two main chromosomal translocations to define EHE tumours. The most common of these, t(1;3), results in expression of the TAZ-CAMTA1 (TC) fusion protein. Little is known about the mechanism of action of TC, however it is thought to share similarities with wild-type TAZ, a transcriptional co-activator downstream of the Hippo pathway. To date, in vitro investigations into TC regulation and function have used transformed, non-endothelial cell lines as a model system. Whilst these have furthered our knowledge of EHE biology, it is important to determine the consequences of TC expression in endothelial cells, as wild-type TAZ has cell context-dependent effects. This project aims to develop such model, by optimising a protocol for differentiating mouse embryonic stem cells (mESCs) into endothelial cells. A doxycycline-inducible system is used to allow study of the molecular and cellular consequences of TC expression at various stages of endothelial development. Using this model, I uncover a role for TC expression in promoting the dedifferentiation of endothelial cells. This revealed alterations to the endothelial cell immunophenotype and upregulation of signalling pathways relating to stem cell regulation. It is also uncovered that TC expression promotes hypertranscription in endothelial cells. Subsequently, cells acquire DNA damage and are subject to cell cycle arrest, potentially representative of the indolent phase of human EHE. This leaves cells prone to the acquisition of secondary mutations, which occur in 55% of EHE tumours. Here, CRISPR/Cas9 mediated knockout of Cdkn2a, the most common secondary mutation in EHE, facilitates increased proliferation and TC expression in endothelial cells. Together, this project characterises multiple cellular and molecular processes which may contribute to the development of TC-driven EHE. Moreover, the in vitro model of EHE can be utilised for further study into TC function, building on the concepts presented here. This could ultimately have implications for future EHE treatment strategies and improve patient outcomes.
Date of Award | 1 Aug 2023 |
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Original language | English |
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Awarding Institution | - The University of Manchester
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Supervisor | Valerie Kouskoff (Supervisor) & Georges Lacaud (Supervisor) |
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- Stem cells
- Epithelioid Haemangioendothelioma
- Cancer
- Endothelial
Developing an in vitro model of Epithelioid Haemangioendothelioma
Neil, E. (Author). 1 Aug 2023
Student thesis: Phd