The PAX3-FOXO1 fusion gene reduces cell-ECM interactions and TGFβ signaling in rhabdomyosarcoma.

We identify downregulation of genes related to cell-ECM interactions and TGFβ signaling in FPRMS. We confirm that TGFβ signaling enhances cell-ECM interactions in FNRMS, utilizing confocal reflection microscopy to assess ECM remodeling, and a live-cell sensor to quantitatively assess TGFβ signaling. We also show that PAX3-FOXO1 increases NOS1 expression, stimulating nitric oxide synthesis, which inhibits TGFβ signaling and reduces cell-ECM interactions. We suggest that PAX3-FOXO1 reprograms ECM anchorage dependence by suppressing cell-ECM interactions. The fusion gene can determine sensitivity to growth inhibition via targeted disruption of cell-ECM interactions or TGFβ signaling. Reduced anchorage reliance by the gene may allow cells to survive in circulation and enhance FPRMS metastatic potential.