Retinoic acid suppresses MYB in adenoid cystic carcinoma [ChIP-seq]

Translocations that drive overexpression of the oncogenic transcription factor MYB are molecular hallmarks of adenoid cystic carcinoma (ACC), a malignant salivary gland tumor. Surgical resection, whenever possible, is the standard therapy for ACC, but there are no available therapeutic options available if surgery fails. Here we performed a chemical genetic screen using a zebrafish embryo culture system and identified retinoic acid agonists as potent suppressors of c-myb. Retinoic acid treatment strongly decreased c-myb gene expression in U937 cells and suggested a direct transcriptional mechanism of regulation. Retinoic acid agonists strongly inhibited tumor growth in vivo in different ACC patient derived xenograft models. Analysis of the xenografts revealed a significant decrease in MYB binding at translocated enhancers, thereby disrupting the MYB positive feedback loop that drives ACC. Our findings identify an important role of retinoic acid in MYB regulation and as a potential new effective therapy for ACC. ChIP-seq analysis of myb, RAR, and H3K27ac in ACC xenograft samples treated with vehicle or ATRA