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

Allegra G Hawkins,Kelsey Temprine,Colin Sperring,Sydney Treichel,Brian Magnuson,Elizabeth R Lawlor,Elisabeth A Pedersen,Jay A Read,Rashmi Chugh

doi:10.1172/jci.insight.135188

Abstract

Wnt/β-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 β-catenin-activated Ewing sarcoma cells also alter secretion of extracellular matrix (ECM) proteins. We thus hypothesized that, in addition to cell-autonomous mechanisms, Wnt/β-catenin-active tumor cells might contribute to disease progression by altering the tumor microenvironment (TME). Analysis of transcriptomic data from primary patient biopsies and from β-catenin-active versus -nonactive tumor cells identified angiogenic switch genes as being highly and reproducibly upregulated in the context of β-catenin activation. In addition, in silico and in vitro analyses, along with chorioallantoic membrane assays, demonstrated that β-catenin-activated Ewing cells secreted factors that promote angiogenesis. In particular, activation of canonical Wnt signaling leads Ewing sarcoma cells to upregulate expression and secretion of proangiogenic ECM proteins, collectively termed the angiomatrix. Significantly, our data show that induction of the angiomatrix by Wnt-responsive tumor cells is indirect and is mediated by TGF-β. Mechanistically, Wnt/β-catenin signaling antagonizes EWS-FLI1-dependent repression of TGF-β receptor type 2, thereby sensitizing tumor cells to TGF-β ligands. Together, these findings suggest that Wnt/β-catenin-active tumor cells can contribute to Ewing sarcoma progression by promoting angiogenesis in the local TME.

Highlights

Tumor growth and metastatic progression are dependent on both tumor cell–autonomous factors and the local tumor microenvironment (TME) [1]
We first evaluated whether expression of lymphoid enhancer binding factor 1 (LEF1), a previously established marker for activated Wnt/β-catenin in Ewing sarcoma tumor cells [11], in primary tumors correlates with expression of genes involved in tumor/TME interaction
In this work we provide evidence that activation of canonical Wnt signaling in Ewing sarcoma tumor cells contributes to activation of the angiogenic switch in the local TME

Summary

Introduction

Tumor growth and metastatic progression are dependent on both tumor cell–autonomous factors and the local tumor microenvironment (TME) [1]. Heterogeneity of tumor cells, the ECM, and other TME components, in time and space, contributes to a highly dynamic tumor ecosystem that modulates disease progression [2, 3]. Ewing sarcomas are aggressive bone and soft tissue tumors with peak incidence in adolescents and young adults [4]. They are defined by an undifferentiated cellular histology and characteristic chromosomal translocations that create EWS-ETS fusion proteins, the most common of which is EWS-FLI1 [5]. In order to advance understanding of the mechanisms that drive Ewing sarcoma relapse and metastasis, it is critical to elucidate the factors that contribute to the dynamic Ewing sarcoma ecosystem, in particular to heterogeneity of tumor cells and the TME

Methods

Results

Conclusion