Wnt/beta-catenin activated Ewing sarcoma cells promote the angiogenic switch

Wnt/beta-catenin signaling is active in small subpopulations of Ewing sarcoma cells and these cells display a more metastatic phenotype, in part due to antagonism of EWS-FLI1-dependent transcriptional activity. Importantly, these beta-catenin-activated Ewing cells also alter secretion of extracellular matrix (ECM) proteins. We thus hypothesized that, in addition to cell autonomous mechanisms, Wnt/beta-catenin-active tumor cells might contribute to disease progression by altering the tumor microenvironment (TME). Activation of canonical Wnt signaling leads Ewing sarcoma cells to upregulate expression and secretion of pro-angiogenic ECM proteins, collectively termed the angiomatrix. Here we tested the role of Wnt-related TGF-beta signaling in angiomatrix induction by obtaining mRNA from Wnt3a-treated TC32 cells in the presence and absence of SB505124, a chemical inhibitor of TGF-beta receptor 1 (TGFBR1) and subjecting it to short read RNA-sequencing. Overall design: Cultured TC32 Ewing sarcoma cells were treated with vehicle (control), Wnt (28 h), or both Wnt (28 h) and a TGF-beta signaling inhibitor (SB-505124, 24 h) prior to assay by RNA-seq, with three replicates per condition.