Dissertation

In vivo modelling of Ewing sarcoma in zebrafish

Promotores: Prof.dr. P.C.W. Hogendoorn & Prof.dr. H.P. Spaink, Co-promotor: Dr. B.E. Snaar-Jagalska

Author: W. van der Ent
Date: 22 October 2015
Links: Thesis in Leiden Repository

Ewing sarcoma (EWS) is a disease with a high need for novel therapeutic strategies. To aid in investigating such compounds in an in vivo setting, we have developed several zebrafish model systems for EWS, which are presented in this thesis. The first is a manual xenograft model in 2-day-old zebrafish embryos, in which cell behaviour on the level of proliferation and migration has been described, as well as their interaction with the host innate immunesystem. With this model, we found that simultaneous induction of the p53 pathway and disruption of EWS-FLI1 transcriptional activity had an additive effect on the reduction of EWS malignancy in vivo. The same model was used to explore the mechanism of NOTCH-induced tumour suppression, via Sirtuin1 (SIRT1) inhibition. In addition to this manual xenograft model, we also established a high-throughput automated implantation model in blastula stage embryos. Furthermore, a flexible transgenic model has been developed, where human EWSR1-ERG expression has been placed under an UAS promoter, allowing the gene to be expressed in different tissues at different times. When this EWS-driving fusiongene was expressed neuronally, overlap in gene and protein expression was found with other EWS models, as well as a histologic similarity to EWS tumours.