Unraveling Ewing Sarcoma Tumorigenesis Originating from Patient-Derived Mesenchymal Stem Cells

Abstract

Ewing sarcoma is characterized by pathognomonic translocations, most frequently fusing EWSR1 with FLI1. An estimated 30% of Ewing sarcoma tumors also display genetic alterations in STAG2, TP53, or CDKN2A (SPC). Numerous attempts to develop relevant Ewing sarcoma models from primary human cells have been unsuccessful in faithfully recapitulating the phenotypic, transcriptomic, and epigenetic features of Ewing sarcoma. In this study, by engineering the t(11;22)(q24;q12) translocation together with a combination of SPC mutations, we generated a wide collection of immortalized cells (EWIma cells) tolerating EWSR1-FLI1 expression from primary mesenchymal stem cells (MSC) derived from a patient with Ewing sarcoma. Within this model, SPC alterations strongly favored Ewing sarcoma oncogenicity. Xenograft experiments with independent EWIma cells induced tumors and metastases in mice, which displayed bona fide features of Ewing sarcoma. EWIma cells presented balanced but also more complex translocation profiles mimicking chromoplexy, which is frequently observed in Ewing sarcoma and other cancers. Collectively, these results demonstrate that bone marrow–derived MSCs are a source of origin for Ewing sarcoma and also provide original experimental models to investigate Ewing sarcomagenesis. Significance: These findings demonstrate that Ewing sarcoma can originate from human bone-marrow–derived mesenchymal stem cells and that recurrent mutations support EWSR1-FLI1 translocation-mediated transformation.

TrkC, a novel prognostic marker, induces and maintains cell survival and metastatic dissemination of Ewing sarcoma by inhibiting EWSR1-FLI1 degradation

“…Malignancy affects the morphogenesis and acquisition of the self-renewing trait of CSCs [ 27 , 28 ]. In our study, we examined whether TrkC affected cell proliferation at a clonal density associated with the mesenchymal stem cell population [ 29 , 30 ]. The sphere-forming cell population in the control TC252 and TC71 cells were 3.8- and 5-folds of the respective TrkC-shRNA cells (Fig.…”

De novo generation of the NPM-ALK fusion recapitulates the pleiotropic phenotypes of ALK+ ALCL pathogenesis and reveals the ROR2 receptor as target for tumor cells

“…T lymphocytes were transfected at 5 to 7 days post CD3/CD28 activation, with the RNP/Cas9 complex using the 4D Nucleofector Amaxa technology (Lonza) (using the gRNA NPM and gRNA ALK and the Cas9 protein (quantity ratio 2:1) and as described in [ 19 ]). IL-2 (40 U/mL) was added in the media once at the time of transfection but never used afterwards.…”

Ewing sarcoma and related FET family translocation‐associated round cell tumors: A century of clinical and scientific progress

“…Returning to the narrower story of Ewing sarcoma, it is important to recognize that different mechanisms may give rise to a EWSR1 or related gene fusion. While simple translocations are one mechanism of fusion gene development, elegant work demonstrated that all the examined ERG ‐translocated and some FLI1 ‐translocated ES arose from a cascade of chromosomal translocations termed chromoplexy 33,34 . Small round cell sarcomas with a chromoplexy‐associated ES appear to have an inferior outcome to patients with an ES with a simple EWSR1::FLI1 fusion.…”

“…While simple translocations are one mechanism of fusion gene development, elegant work demonstrated that all the examined ERG-translocated and some FLI1-translocated ES arose from a cascade of chromosomal translocations termed chromoplexy. 33,34 Small round cell sarcomas with a chromoplexy-associated ES appear to have an inferior outcome to patients with an ES with a simple EWSR1::FLI1 fusion. This mechanism finally provides a plausible explanation for the poor outcomes of adults compared to children with the same translocation-associated sarcoma diagnosis.…”