Abstract: | Testicular germ cell tumours of adults and adolescents (TGCT) include seminomas and nonseminomas, with spermatocytic seminomas representing a distinct entity in older men. Seminomas and nonseminomas have gain of 12p material in all cases whereas spermatocytic seminomas are associated with overrepresentation of chromosome 9. Here we compare at the chromosomal level, copy number imbalances with global expression changes, identified by comparative expressed sequence hybridisation analyses, in 7 seminomas, 1 combined tumour, 7 nonseminomas and 7 cell lines. Positive correlations were found consistent with copy number as a main driver of expression change, despite reported differences in methylation status in seminomas and nonseminomas. Analysis of chromosomal copy number and expression data could not distinguish between seminomas and nonseminomas, in-keeping with a similar genetic pathogenesis. However, increased expression from 4q22, 5q23.2 and 9p21 distinguished spermatocytic seminomas from seminomas and nonseminomas and decreased copy number and expression from 2q36-q37 and 6q24 was a specific feature of nonseminoma derived cell lines. Our analysis also highlights 19 regions with both copy number and expression imbalances in greater than 40% of cases. Mining available expression array data identified genes from these regions as candidates for involvement in TGCT development. |