Multiple myeloma (MM), a terminally differentiated B-cell malignancy, remains difficult to cure. Understanding the molecular mechanisms underlying the progression of MM may identify therapeutic targets and lead to a fundamental shift in treatment of the disease. Deubiquitination like ubiquitination is a highly regulated process, implicated in almost every cellular process. Multiple deubiquitinating enzymes (DUBs) have been identified but their regulation is poorly defined. Here, we determined that TRIP13 increases cellular deubiquitination. Overexpression of TRIP13 in mice and cultured cells resulted in excess cellular deubiquitination by enhancing the association of the DUB USP7 with its substrates. We show that TRIP13 is an oncogenic protein because it accelerates B-cell tumor development in transgenic mice. TRIP13-induced resistance to proteasome inhibition can be overcome by a USP7 inhibitor in vitro and in vivo. These findings point to a critical role for TRIP13 expression in B-cell lymphoma and MM by governing deubiquitination of critical oncogenic (NEK2) and tumor suppressor (PTEN, P53) proteins. High TRIP13 identifies a high-risk patient group amendable to adjuvant anti-USP7 therapy.
Can Li, Jiliang Xia, Reinaldo Franqui Machin, Fangping Chen, Yanjuan He, Timothy Cody Ashby, Feixiang Teng, Hongwei Xu, Dingxiao Liu, Dongzheng Gai, Sarah K. Johnson, Frits van Rhee, Siegfried Janz, John D. Shaughnessy Jr, Guido Tricot, Ivana Frech, Fenghuang Zhan