Small-molecule inhibitor of USP7/HAUSP ubiquitin protease stabilizes and activates p53 in cells

Mol Cancer Ther. 2009 Aug;8(8):2286-95. doi: 10.1158/1535-7163.MCT-09-0097. Epub 2009 Aug 11.


Deregulation of the ubiquitin/proteasome system has been implicated in the pathogenesis of many human diseases, including cancer. Ubiquitin-specific proteases (USP) are cysteine proteases involved in the deubiquitination of protein substrates. Functional connections between USP7 and essential viral proteins and oncogenic pathways, such as the p53/Mdm2 and phosphatidylinositol 3-kinase/protein kinase B networks, strongly suggest that the targeting of USP7 with small-molecule inhibitors may be useful for the treatment of cancers and viral diseases. Using high-throughput screening, we have discovered HBX 41,108, a small-molecule compound that inhibits USP7 deubiquitinating activity with an IC(50) in the submicromolar range. Kinetics data indicate an uncompetitive reversible inhibition mechanism. HBX 41,108 was shown to affect USP7-mediated p53 deubiquitination in vitro and in cells. As RNA interference-mediated USP7 silencing in cancer cells, HBX 41,108 treatment stabilized p53, activated the transcription of a p53 target gene without inducing genotoxic stress, and inhibited cancer cell growth. Finally, HBX 41,108 induced p53-dependent apoptosis as shown in p53 wild-type and null isogenic cancer cell lines. We thus report the identification of the first lead-like inhibitor against USP7, providing a structural basis for the development of new anticancer drugs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis
  • Cell Line, Tumor
  • Cell Proliferation
  • Cells, Cultured
  • Dose-Response Relationship, Drug
  • Humans
  • Indenes / pharmacology*
  • Protease Inhibitors / pharmacology*
  • Pyrazines / pharmacology*
  • Tumor Suppressor Protein p53 / genetics
  • Tumor Suppressor Protein p53 / metabolism*
  • Ubiquitin Thiolesterase / antagonists & inhibitors*
  • Ubiquitin Thiolesterase / metabolism
  • Ubiquitin-Specific Peptidase 7


  • HBX 41,108
  • Indenes
  • Protease Inhibitors
  • Pyrazines
  • Tumor Suppressor Protein p53
  • USP7 protein, human
  • Ubiquitin Thiolesterase
  • Ubiquitin-Specific Peptidase 7