BRD7 is a candidate tumour suppressor gene required for p53 function. Homo sapiens

Oncogene-induced senescence (OIS) is a p53-dependent defence mechanism against uncontrolled proliferation. Consequently, many human tumours harbour p53 mutations while others show a dysfunctional p53 pathway, frequently by unknown mechanisms. We identified BRD7, a bromodomain-containing protein whose inhibition allows full neoplastic transformation in the presence of wild-type p53. Intriguingly, in human breast tumours harbouring wild-type, but not mutant p53, the BRD7 gene locus was frequently deleted and low BRD7 expression was found in a subgroup of tumours. Functionally, BRD7 is required for efficient p53-mediated transcription of a subset of target genes. BRD7 interacts with p53 and p300, and is recruited to target gene promoters, affecting histone acetylation, p53 acetylation, and promoter activity. Thus, BRD7 suppresses tumourigenicity by serving as a p53 cofactor required for efficient induction of p53-dependent OIS. Overall design: We recorded mRNA expression profiles of BJ primary fibroblasts expressing the oncogene RasV12 and either control vector, one of two BRD7 knockdown vectors, or p53 knockdown vector. In addition, we profiled genome-wide protein DNA interactions for p53 and BRD7 using ChIP-Seq. p53- and BRD7-binding sites were recorded in RasV12-expressing BJ cells; as a control we used knockdown of the gene of interest (BRD7 or p53).