The SAGA complex maintains the oncogenic gene expression program in MYCN-amplified neuroblastoma [RNA-Seq]

Pediatric cancers are frequently driven by fusion or amplification events that result in aberrant transcription factor activity. As transcription factors themselves remain challenging to target, an emerging therapeutic approach for these cancers is to target epigenetic complexes that help maintain oncogenic transcriptional programs. It is therefore critical to identify the complete set of epigenetic modulators maintaining the oncogenic epigenetic landscape of pediatric cancers. Here, we used functional genomic screens to identify epigenetic complexes critical for viability in cell line models of MYCN-amplified neuroblastoma, a disease of dysregulated development driven by an aberrant oncogenic transcriptional program. We identified multiple genes within the transcriptional coactivator Spt-Ada-Gcn5-acetyltransferase (SAGA) complex as selective dependencies in MYCN-amplified neuroblastoma. Integrating ChIP-seq, ATAC-seq, and RNA-seq with targeted protein-degradation and gene editing tools, we characterized the DNA recruitment sites of the SAGA complex in neuroblastoma, and the consequences of SAGA complex lysine acetyltransferase (KAT) activity loss on histone acetylation and gene expression. We demonstrate that loss of SAGA KAT activity suppresses MYC and MYCN gene expression programs and impairs cell cycle progression. Further, we showed that the SAGA complex is pharmacologically targetable with a KAT2A/KAT2B proteolysis targeting chimera molecule that demonstrated significant activity in vitro and in vivo. Our findings expand our understanding of the histone modifying complexes that maintain the oncogenic transcriptional state in this disease and suggest therapeutic potential for inhibitors of SAGA KAT activity in MYCN-amplified neuroblastoma.