Pluto Biosciences, Inc

GSE151514: Identification of 17-DMAG as a novel KDM4B inhibitor for combination therapy [RNA-seq]

Bulk RNA sequencing

Histone lysine demethylases (KDMs) are emerging as therapeutic targets in cancer. Development of potent KDM inhibitors may provide additional options for epigenomics-oriented therapies. Using a Time-Resolved Fluorescence Resonance Energy Transfer (TR-FRET) functional demethylation assay, in combination with a high-content immunofluorescence imaging phenotypic screen, Matrix-Assisted Laser Desorption/Ionization- Fourier Transform Ion Cyclotron Resonance mass spectrometry (MALDI-FTICR MS) and Amplified Luminescent Proximity Homogeneous Assay (ALPHA), we identified geldanamycin, an inhibitor of heat shock protein 90 (Hsp90), as a novel inhibitor of JmjC-domain containing demethylases such as KDM4B. We further found that geldanamycin can destabilize the PAX3-FOXO1 fusion oncoprotein, an Hsp90 client, which is a driver of clinically unfavorable alveolar rhabdomyosarcoma (aRMS). We then hypothesized that dual inhibition of PAX3-FOXO1 and epigenetic modifiers of aRMS would have synergistic antitumor activity. We repurposed the geldanamycin analog 17-DMAG to target aRMS and found that 17-DMAG significantly delays tumor growth , extends survival in xenograft mouse models, and inhibits expression of PAX3-FOXO1 targets and multiple oncogenic pathways including MYC, E2F and NOTCH. In addition, the combination of 17-DMAG with conventional chemotherapy or the bromodomain inhibitor JQ1 significantly enhances therapeutic efficacy. In summary, we have identified geldanamycin and 17-DMAG as dual KDM/Hsp90 inhibitors and 17-DMAG is efficacious against PAX3-FOXO1-driven rhabdomyosarcoma. SOURCE: Hongjian Jin (hongjian.jin@STJUDE.ORG) - St Jude Children's Research Hospital

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