YM155 inhibits neuroblastoma growth through degradation of MYCN: A new role as a USP7 inhibitor.

Amplification of the MYCN gene (MNA) is observed in approximately 25 to 35% of neuroblastoma patients, and is a well-recognized marker of tumor aggressiveness and poor outcome. Targeting MYCN is a novel therapy strategy to induce tumor regression. Here, we discovered that a BIRC5/Survivin inhibitor, YM155, specifically inhibits MNA neuroblastoma cell growth in vitro. We found that YM155 promotes MYCN degradation in MNA cells. Further, we found that YM155 inhibits USP7 deubiquitinase activity in vitro, using Ub-aminomethylcoumarin (Ub-AMC) as substrate. Results from in vivo studies further demonstrated that YM155 significantly inhibited the tumor growth in MNA neuroblastoma xenograft model. Our data support a novel mechanism of action of YM155 in inhibition of growth of cancer cells through inducing MYCN degradation by inibition of activity of deubiquitinase like USP7.