An oncogenic MYB feedback loop drives alternate cell fates in adenoid cystic carcinoma

Bradley Bernstein, Birgit Knoechel and colleagues identify super-enhancer translocations that drive overexpression of MYB in adenoid cystic carcinoma (ACC). They find that MYB binds to the translocated enhancers and to other active enhancers that drive different regulatory programs in alternate cell lineages in ACC. Translocation events are frequent in cancer and may create chimeric fusions or 'regulatory rearrangements' that drive oncogene overexpression. Here we identify super-enhancer translocations that drive overexpression of the oncogenic transcription factor MYB as a recurrent theme in adenoid cystic carcinoma (ACC). Whole-genome sequencing data and chromatin maps highlight distinct chromosomal rearrangements that juxtapose super-enhancers to the MYB locus. Chromosome conformation capture confirms that the translocated enhancers interact with the MYB promoter. Remarkably, MYB protein binds to the translocated enhancers, creating a positive feedback loop that sustains its expression. MYB also binds enhancers that drive different regulatory programs in alternate cell lineages in ACC, cooperating with TP63 in myoepithelial cells and a Notch program in luminal epithelial cells. Bromodomain inhibitors slow tumor growth in ACC primagraft models in vivo . Thus, our study identifies super-enhancer translocations that drive MYB expression and provides insight into downstream MYB functions in alternate ACC lineages.