American Association for Cancer Research
15357163mct140064-sup-125804_2_supp_2613244_n4c246.pptx (73.99 kB)

Supplementary Figure 2 from CBS9106-Induced CRM1 Degradation Is Mediated by Cullin Ring Ligase Activity and the Neddylation Pathway

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posted on 2023-04-03, 14:00 authored by Naoya Saito, Keiichi Sakakibara, Takuji Sato, Jonathan M. Friedman, Donald W. Kufe, Daniel D. VonHoff, Takumi Kawabe

Supplementary Figure 2: MLN4924 (50 nM) increases subG1 and DNA content. HCT116 cells are treated with increasing concentrations of MLN4924 (0, 1, 10, or 50 nM) for 72 hours. The population is measured by flow cytometry after staining with propidium iodide (n = 3). Data are expressed as the mean {plus minus} SD.



Chromosome region maintenance 1 (CRM1) mediates the nuclear export of proteins and mRNAs, and is overexpressed in various cancers. Recent studies have also reported that CRM1 protein expression is a negative prognostic factor in patients with cancer. Therefore, CRM1 is considered a potential target for anticancer therapy. Our previous study demonstrated that CBS9106, a synthetic small-molecular inhibitor of CRM1, decreases CRM1 protein through proteasomal degradation without affecting CRM1 mRNA levels. However, the mechanism by which CRM1 is degraded is not well understood. Here, we demonstrate a novel signaling pathway that plays an important role in CBS9106-induced CRM1 degradation. We found that MLN4924, a selective inhibitor of NEDD8-activating enzyme (NAE), effectively inhibits cullin neddylation and attenuates CBS9106-induced CRM1 degradation in a time- and dose-dependent manner. MLN4924 also attenuated CBS9106-induced nuclear accumulation of Ran-binding protein 1 (RanBP1), cell growth inhibition, and apoptosis. Furthermore, RNAi-mediated knockdown of neddylation pathway proteins (NEDD8 and UBA3) or cullin ring ligase (CRL) component protein (Rbx1) attenuated CRM1 protein degradation and G1 phase cell-cycle arrest by CBS9106. Knockdown of CSN5 or CAND1 also partially inhibited CBS9106-induced CRM1 degradation. These findings demonstrate that CBS9106-induced CRM1 degradation is conferred by CRL activity involving the neddylation pathway, and that this response to CBS9106 leads to cell growth inhibition and apoptosis. Mol Cancer Ther; 13(12); 3013–23. ©2014 AACR.