Genome-wide CRISPRa screen identifies determinants of Actinomycin-D resistance in alveolar rhabdomyosarcoma

Rhabdomyosarcomas (RMS) are the most common soft tissue sarcomas in children and adolescents. Even with current multi-modal treatment strategies combining surgery, radiotherapy and poly-chemotherapy such as Actimomycin D (ActD), Vincristine and Ifosfamide, outcomes of patients with relapsed or high-risk metastatic alveolar RMS remain dismal. Even though ActD is administered to the majority of patients with RMS, the determinants of sensitivity and resistance towards ActD are largely unknown. Here, we used a CRISPR-based genome-wide gene activation screen to identify genes contributing to resistance against ActD. In addition to ABCC1, a drug pump already described to confer resistance to ActD, we identified several genes encoding for transcriptional regulators of cell differentiation to be sufficient to induce resistance to ActD in vitro. CRISPR guide RNA target genes inducing resistance to ActD were validated using cell viability assays. Comparing genes differentially expressed between RMS patient-derived xenografts that were either sensitive or resistant to ActD with the results of our CRISPRa screen further refined our list of potential regulators of ActD resistance in RMS.

Publication History

Article published online:
13 May 2020