Gene expression and knockdown systems are powerful tools to study the function of single genes and their pathway interaction. Plasmid transfection and viral transduction have revolutionized the field of molecular biology and paved the ground for various gene-editing strategies such as TALEN, zinc finger nucleases, and ultimately CRISPR. In Ewing sarcoma (EwS), almost as many genes are repressed by the expression of EWSR1-FLI1 as are upregulated by the fusion oncogene. Here we present a useful point-to-point protocol for the generation of transgene expression systems in EwS that allow (conditional) reexpression of a gene of interest. We provide an extensive instruction on molecular cloning, plasmid generation, viral transduction, and expression validation. Finally, we address common problems and highlight potential pitfalls, which can easily be avoided by thoughtful guidance.
Keywords: Enhancer; Ewing sarcoma; Fusion-driven sarcoma; Gene expression; Inducible vector; Microsatellites; Overexpression; Promoter.