Multi-omics profiling reveals key factors involved in Ewing sarcoma metastasis.

Ewing sarcoma (EWS) is the second most common bone tumor affecting children and young adults, with dismal outcomes for patients with metastasis at diagnosis. Mechanisms leading to metastasis remain poorly understood. To deepen our knowledge on EWS progression, we have profiled tumors and metastases from a spontaneous metastasis mouse model using a multi-omics approach. Combining transcriptomics, proteomics, and methylomics analyses, we identified signaling cascades and candidate genes enriched in metastases that could be modulating aggressiveness in EWS. Phenotypical validation of two of these candidates, cyclic AMP-responsive element-binding protein 1 (CREB1) and lipoxygenase homology domain-containing protein 1 (LOXHD1), showed an association with migration and clonogenic abilities. Moreover, previously described CREB1 downstream targets were present amongst the metastatic-enriched results. Combining the different omics datasets, we identified FYVE, RhoGEF, and PH domain-containing protein 4 (FGD4) as a CREB1 target interconnecting the different EWS biological layers (RNA, protein and methylation status) and whose high expression is associated with worse clinical outcome. Further studies will provide insight into EWS metastasis mechanisms and ultimately improve survival rates for EWS patients.