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Chromosomal translocations have been well studied in haematopoietic tumours, but with respect to solid tumours, consistent translocations have only been observed in sarcomas. Synovial sarcoma is a soft tissue tumour occurring predominantly in the adolescent age group of 10-20. A key molecular event in the development of this disease is thought to be the t(X,:18) translocation involving the SS18 gene on chromosome 18 and the SX gene family members 1,2 and occasionally 4 on chromosome X. The aim of this project was to clone cDNA for the fusion genes produced, SS18/SSXI and SS18/SSX2, and also the full-length wild type genes SSX1, SSX2, and SS18. This bank of clones would then be used for functional studies into the role these genes play in normal and malignant environments. To achieve this a PCR based cloning strategy was employed. By amplification of the gene of interest using specific primers located in the 5’ and 3’ flanking regions of the gene, full-length cDNA could be generated for insertion into plasmid. Fully characterised clones were transfected into cell lines to study transcript and protein expression. During this project sequencing S18/SSX2 clone led to the discovery of an unidentified exon (exon 8) in the SS18 portion of the fusion gene. Analysis of wild type SS18 gene expression indicated mRNA splicing into at least two transcripts in human tissues and four in mice, with varying expression levels throughout the tissue types tested. In melanoma tumour samples over expression of the SS18 transcript lacking exon 8 was observed indicating a possible role for this particular transcript in the tumourigenesis process. The molecular function of the genes associated with synovial sarcoma is largely unknown, although recent publications point toward a role in transcription control. The clones produced in this study will provide a platform for in vitro studies into the unction of the wild type and fusion proteins.
Haslam, K. (2006). Molecular cloning of wild type and fusion genes associated with the t(X;18) translocation in synovial sarcoma. Masters dissertation. Technological University Dublin. doi:10.21427/D78C9W