Enhanced Drug Repurposing Screen in DSRCT Enabled by New In Vitro and In Vivo Models Based on CRISPR/Cas9 Genome Engineering

Project Summary:

Pediatric and young adult sarcomas are orphan diseases with few rationally targeted pharmacological agents. Laboratory studies of sarcomas carrying chromosomal rearrangements, such as Desmoplastic small round cell tumor (DSRCT), have often been hampered by the lack of adequate patient-derived cell lines and suitable mouse models. This proposal takes a highly innovative approach to tackle these issues by employing a novel genomic editing technology to generate new cell line and mouse models for DSRCT. DSRCT is defined molecularly by the presence of a specific chromosomal rearrangement which results in the fusion of portions of the EWSR1 and WT1 genes. The resulting abnormal protein drives this very aggressive tumor in children and young adults. As a proof of principle, we have generated the EWS-WT1 fusion in human mesenchymal stem cells (hMSC) using the CRISPR/Cas9 genomic editing technology. This provides us with a unique model cell line that we will use to evaluate 90 compounds previously identified as potentially active against other DSRCT cell lines. We will also engineer the oncogenic EWS-WT1 fusion in a mouse using an innovative approach to perform the CRISPR/Cas9 genomic editing in vivo. This pre-clinical mouse model of DSRCT will allow us to further evaluate the efficacy of our new therapies for DSRCT.