67 Background: Structural rearrangements in cancers genomes have the potential to disrupt normal gene function and result in a selective growth advantage, either by inactivating tumour suppressors or creating novel gene fusions with oncogenic gain-of-function. Specific fusion genes identified to date are found in particular tumor types rather than being present in all cancers suggesting there are tissue-specific mechanisms underlying these events. The most well-known fusion event in prostate cancer is TMPRSS2-ERG. Recent studies have suggested that androgen receptor may play a role in the formation of TMPRSS2-ERG fusions, bringing the two loci in close proximity in the nucleus and facilitating DNA strand break and repair along with AR associated enzymes. Methods: To explore this mechanism more comprehensively, we performed whole-genome sequencing of 14 prostate cancers from seven patients as well as paired whole blood controls. Results: Across the cancer genomes we identified approximately 4,500 high confidence DNA breakpoints and found that a large proportion of these breakpoints were in close proximity to curated androgen receptor binding sites. Furthermore, when we examined breakpoints in 11 other cancers from the TCGA and ICGC projects, we identified a similar association with androgen (and estrogen) receptor binding sites specifically in hormone-dependent tumour types, suggesting a role for steroid hormone receptors in the formation of cancer driving structural rearrangements. In addition, in at least one patient, the formation of a novel gene fusion contributed directly to the lethal evolution of his tumour. Conclusions: These data suggest that the androgen receptor drives genome wide breakpoints and novel fusion events in prostate cancer.
Research Resource: Genome-Wide Mapping of in Vivo Androgen Receptor Binding Sites in Mouse Epididymis
