American Association for Cancer Research
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Supplementary Figure S1 F-I from Drugging MYCN Oncogenic Signaling through the MYCN-PA2G4 Binding Interface

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posted on 2023-03-31, 03:45 authored by Jessica Koach, Jessica K. Holien, Hassina Massudi, Daniel R. Carter, Olivia C. Ciampa, Mika Herath, Taylor Lim, Janith A. Seneviratne, Giorgio Milazzo, Jayne E. Murray, Joshua A. McCarroll, Bing Liu, Chelsea Mayoh, Bryce Keenan, Brendan W. Stevenson, Michael A. Gorman, Jessica L. Bell, Larissa Doughty, Stefan Hüttelmaier, Andre Oberthuer, Matthias Fischer, Andrew J. Gifford, Tao Liu, Xiaoling Zhang, Shizhen Zhu, W. Clay Gustafson, Michelle Haber, Murray D. Norris, Jamie I. Fletcher, Giovanni Perini, Michael W. Parker, Belamy B. Cheung, Glenn M. Marshall

Supplementary Figure S1. F, Confocal microscopy of SHEP Tet21N cells using anti-PA2G4 (red) and anti-MYCN (green) antibodies. G, Immunoblot analysis of cytoplasmic and nuclear fractions from BE(2)-C and Kelly human neuroblastoma cell lines with antibodies recognizing PA2G4 and MYCN, or GAPDH and topoisomerase as loading controls. H, Confocal microscopy of neuroblastoma (BE(2)-C and Kelly) cells using anti-PA2G4 (red) and anti-MYCN (green) antibodies. Alexafluor 555 anti-rabbit (to detect PA2G4) and Alexafluor 488 anti-mouse (to detect MYCN) were used as the secondary antibodies. I, Real-time PCR mRNA expression of MYCN and PA2G4 in ganglia from homozygote TH-MYCN+/+ mice, compared to wild type littermate control mice, obtained at different postnatal age (weeks).

Funding

National Health and Medical Research Counci

NHMRC

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ARTICLE ABSTRACT

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). Chromatin immunoprecipitation 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 modeling, surface plasmon resonance, and mutagenesis studies, we mapped the MYCN–PA2G4 interaction site to a 14 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 a cofactor in MYCN-driven neuroblastoma and highlight competitive inhibition of the PA2G4-MYCN protein binding as a novel therapeutic strategy in the disease. 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.