Integrative gene network and functional analyses identify a prognostically relevant key regulator of metastasis in Ewing sarcoma

Similar in vitro and in vivo experiments performed with both cell lines ‘empty’ controls exhibited no significant differences (Supplementary Fig. 2a, c-d, g-i). Since stemness features, such as elevated clonogenic capacity and anchorage-independent growth, are essential for circulating tumor cells to colonize and develop into clinically apparent metastases in distant organs, we reasoned that TCF7L1 may be linked to the metastatic process in EwS. [...]re-expression of TCF7L1 resulted in significantly reduced transwell migration (Fig. 2b), invasion, and single-cell 3D migration in fibrin gel using advanced microfluidic chambers (Fig. 2c). DNA binding domain; ΔCTNNB: β-catenin binding domain) and observed that only the ΔHMG mutants exhibited a normal clonogenic growth and migration capacity in vitro (Fig. 2h,i), and tumor growth in vivo (Fig. 2j). [...]analysis of our WCGNA on TCF7L1-regulated signatures displayed in Fig. 2a highlighted several downregulated ‘driver target genes’ (aka leading-edge genes), including ANXA1, LMO7, SLC9A9, and TMEM71 as potential key mediators of TCF7L1 inhibition of the EwS migratory phenotype. In this context, we demonstrated that TCF7L1 is a critical mediator of metastasis in EwS, which may be utilized as a prognostic biomarker. Since we could detect a strong inverse correlation of TCF7L1 levels with patients’ overall survival in both the mRNA- as well as in the TMA-cohort, we believe that the most straightforward possibility to translate TCF7L1 into a routine clinical setting would be the IHC detection and semiquantitative evaluation of TCF7L1 in primary biopsies.