Novel, Selective Inhibitors of USP7 Uncover Multiple Mechanisms of Antitumor Activity in Vitro and in Vivo
The human lung tumor cell line, NCI-H526, was treated with DMSO vehicle control or 0.5 µM of the novel small molecule USP7 inhibitor, USP7-797.  At 24 and 48 hour time points, cells were harvested and used for RNA-Seq analysis.  In order to identify pathways impacted by USP7 (Ubiquitin Specific Peptidase 7) inhibition, we used RNASeq to profile transcriptomic changes in human lung cancer NCI-H526 cells following treatment with the novel, selective USP7 inhibitor, USP7-797, or control DMSO for 24 or 48 hours.  USP7 inhibitor treatment resulted in upregulation of a large number of genes normally silenced by the polycomb repressive complex 2 (PRC2).  PRC2, whose components include the proteins EZH2, SUZ12 and EED, trimethylates histone H3 at lysine 27 (H3K27me3).  Gene set enrichment analysis showed that the top 10 significantly enriched gene sets are all regulated by this pathway. RNA was extracted from approximately 1 million cells using the Allprep DNA/RNA Mini Kit (Qiagen).  Whole transcriptome non-stranded libraries were prepared using the TruSeq RNA Library Prep Kit v2 (Illumina).  Sequencing was performed on Illumina NovaSeq using paired-end mode, 200 cycles, targeting 40 million reads per sample. Overall design: USP7-797- or DMSO vehicle-treated H526 cell lines at 24 hours or 48 hours.