GENOME EDITING OF PRIMARY SYNOVIAL SARCOMA CELLS TO PRODUCE V5-TAGGED FUSION SYT-SSX AND TO ALLOW ITS CREMEDIATED SILENCING

Synovial Sarcoma (SS) is a soft tissue neoplasm characterized by the translocation [t(X;18)(p11;q11)] which produces the aberrant fusion protein SYT-SSX. SS is an aggressive tumour which develops mainly in children and young adults, has a poor prognosis, due to its tendency to metastasize, and is frequently resistant to chemo and radiotherapy. To develop new therapeutic approach is required a better understanding of the molecular mechanisms leading to the disease. In recent years it has become clear that SYT-SSX profoundly affects the epigenetic of cells, including mesenchymal cells, which are believed to be SS’ cells of origin. A very powerful approach to measure the epigenetic status of the chromatin and its relations with the transcriptome is the use of Chromatin Immunoprecipitation and deep sequencing (ChIP-seq). These techniques allow the analysis of both histone Post Transcriptional Modifications (PTM) and Epigenetic Regulators (ER) and require the use of high-affinity and low cross-reactivity antibodies targeting proteins of interest. Such antibodies are not available for SYTSSX. To allow a ChIP-seq analysis of the latter, we started preliminary work to add to the genomic sequence of SYT-SSX, a V5 peptide tag, for which a ChIP-grade antibody is available. Furthermore with the same genome editing we allow the Cre-mediated depletion of SYT-SSX while leaving unaffected the wild type counterparts as an important control reagent. This study has the potential to help understanding the molecular pathogenesis behind SS occurrence and aspires to lay the basis for the development of new therapies against the malignancy