Fernández-Tabanera, EnriqueGarcia-Garcia, LauraRodriguez-Martin, CarlosCervera Mayor, Saint ThomasGonzalez-Gonzalez, LauraRobledo, CristinaJosa, SantiagoMartinez Rodríguez, SeleneChapado, LuisMonzon-Fernandez, SaraMelero-Fernández de Mera, Raquel MaríaAlonso, Javier2023-08-282023-08-282023-07-21Int J Mol Sci. 2023 Jul 21;24(14):11774.http://hdl.handle.net/20.500.12105/16354The chimeric EWSR1::FLI1 transcription factor is the main oncogenic event in Ewing sarcoma. Recently, it has been proposed that EWSR1::FLI1 levels can fluctuate in Ewing sarcoma cells, giving rise to two cell populations. EWSR1::FLI1low cells present a migratory and invasive phenotype, while EWSR1::FLI1high cells are more proliferative. In this work, we described how the CD44 standard isoform (CD44s), a transmembrane protein involved in cell adhesion and migration, is overexpressed in the EWSR1::FLI1low phenotype. The functional characterization of CD44s (proliferation, clonogenicity, migration, and invasion ability) was performed in three doxycycline-inducible Ewing sarcoma cell models (A673, MHH-ES1, and CADO-ES1). As a result, CD44s expression reduced cell proliferation in all the cell lines tested without affecting clonogenicity. Additionally, CD44s increased cell migration in A673 and MHH-ES1, without effects in CADO-ES1. As hyaluronan is the main ligand of CD44s, its effect on migration ability was also assessed, showing that high molecular weight hyaluronic acid (HMW-HA) blocked cell migration while low molecular weight hyaluronic acid (LMW-HA) increased it. Invasion ability was correlated with CD44 expression in A673 and MHH-ES1 cell lines. CD44s, upregulated upon EWSR1::FLI1 knockdown, regulates cell migration and invasion in Ewing sarcoma cells.engVoRhttp://creativecommons.org/licenses/by/4.0/Ewing sarcomaCD44EWSR1::FLI1Cell migrationCell invasivenessSarcoma, EwingHumansHyaluronic AcidCell Line, TumorOncogene Proteins, FusionProto-Oncogene Protein c-fli-1Cell MovementGene Expression Regulation, NeoplasticHyaluronan ReceptorsAtribución 4.0 Internacional3751153324141177410.3390/ijms2414117741422-0067International journal of molecular sciencesopen access