Drugging MYCN oncogenic through the interface

MYCN is a major driver for the childhood cancer, neuroblastoma, however, there are no inhibitors of this target. Enhanced MYCN protein stability is a key component of MYCN oncogenesis and is maintained by multiple feedforward expression loops involving MYCN transactivation target genes. Here we reveal the oncogenic role of a novel MYCN target and binding protein, proliferation-associated 2AG4 (PA2G4). ChIP studies demonstrated that MYCN occupies the PA2G4 gene promoter, stimulating transcription. Direct binding of PA2G4 to MYCN protein blocked proteolysis of MYCN, and enhanced colony formation in a MYCN-dependent manner . Using molecular modelling, surface plasmon resonance and mutagenesis studies, we mapped the MYCN-PA2G4 interaction site to a fourteen amino acid MYCN sequence and a surface crevice of PA2G4. Competitive chemical inhibition of the MYCN-PA2G4 protein-protein interface had potent inhibitory effects on neuroblastoma tumorigenesis in vivo. Treated tumors showed reduced levels of both MYCN and PA2G4. Our findings demonstrate a critical role for PA2G4 as cofactor in MYCN-driven neuroblastoma and highlight competitive inhibition of the PA2G4-MYCN protein binding as a novel therapeutic strategy in the disease. Significance: Competitive chemical inhibition of the PA2G4-MYCN protein interface provides a basis for drug design of small molecules targeting MYC and MYCN binding partners in malignancies driven by MYC family oncoproteins. proteins and structural biologic approaches we define a PA2G4-MYCN protein-protein interface which can be inhibited by a known PA2G4-binding compound, with significant anti-tumor effects in vitro and in vivo . Furthermore, we show that PA2G4 expression levels in neuroblastoma patient tumor tissues correlated with MYCN levels and poor prognosis.