Novel, Selective Inhibitors of USP7 Uncover Multiple Mechanisms of Antitumor Activity In Vitro and In Vivo.

Yamini M Ohol,Paul D Kassner,Niket Shah,Jack Maung,Kyle Young,David Wustrow,Deepa Pookot,Jerick Sanchez,Betty Abraham,Delia Bradford,Payal Rana,Lisa A Marshall,Gene Cutler,Paul R Leger,Akinori Okano,Silpa Suthram,Christophe Colas,Dirk G Brockstedt,Scott Jacobson,Xinping Han,Cynthia Cho,Dennis X Hu,Nathan Kozon,Bérenger Biannic ,Michael Sun ,Jacob B Schwarz ,Steve Wong

doi:10.1158/1535-7163.mct-20-0184

Abstract

The deubiquitinase USP7 regulates the levels of multiple proteins with roles in cancer progression and immune response. Thus, USP7 inhibition may decrease oncogene function, increase tumor suppressor function, and sensitize tumors to DNA-damaging agents. We have discovered a novel chemical series that potently and selectively inhibits USP7 in biochemical and cellular assays. Our inhibitors reduce the viability of multiple TP53 wild-type cell lines, including several hematologic cancer and MYCN-amplified neuroblastoma cell lines, as well as a subset of TP53-mutant cell lines in vitro Our work suggests that USP7 inhibitors upregulate transcription of genes normally silenced by the epigenetic repressor complex, polycomb repressive complex 2 (PRC2), and potentiate the activity of PIM and PI3K inhibitors as well as DNA-damaging agents. Furthermore, oral administration of USP7 inhibitors inhibits MM.1S (multiple myeloma; TP53 wild type) and H526 (small cell lung cancer; TP53 mutant) tumor growth in vivo Our work confirms that USP7 is a promising, pharmacologically tractable target for the treatment of cancer.

Highlights

USP7 is a deubiquitinase that regulates the levels of several proteins with roles in cancer development and antitumor immunity
Inhibitor potency was evaluated using a biochemical assay of USP7 activity employing rhodamine-labeled ubiquitin and a cellular activity assay using a p53 response element–driven luciferase reporter engineered into the TP53 wild-type RKO cell line
Using gene annotation data from the Cell Line Encyclopedia (CCLE) [33] to identify mutations that were significantly associated with USP7 inhibitor sensitivity, we found that TP53 mutational status was most significant, with wild-type TP53 status associated with greater sensitivity to USP7 inhibition (Fig. 2A; Supplementary Table S2)

Summary

Introduction

USP7 is a deubiquitinase that regulates the levels of several proteins with roles in cancer development and antitumor immunity. USP7 may stabilize multiple proteins involved in DNA damage repair, imparting resistance to DNA-damaging chemotherapy, PARP inhibitors, and radiotherapy [17, 22,23,24]. Via these mechanisms of action, cell lines of both wild-type and mutant TP53 status have been shown to be directly sensitive to chemical inhibition of USP7. In addition to these tumor intrinsic mechanisms, USP7 has been reported to suppress immune responses in the tumor microenvironment by stabilizing the transcription factor, Foxp, which is essential for the development and function of regulatory T cells (Treg), or by stabilizing

Methods

Results

Conclusion