Destabilizing NEK2 overcomes resistance to proteasome inhibition in multiple myeloma
Reinaldo Franqui-Machin, Mu Hao, Hua Bai, Zhimin Gu, Xin Zhan, Hasem Habelhah, Yogesh Jethava, Lugui Qiu, Ivana Frech, Guido Tricot, Fenghuang Zhan
Reinaldo Franqui-Machin, Mu Hao, Hua Bai, Zhimin Gu, Xin Zhan, Hasem Habelhah, Yogesh Jethava, Lugui Qiu, Ivana Frech, Guido Tricot, Fenghuang Zhan
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Research Article Oncology

Destabilizing NEK2 overcomes resistance to proteasome inhibition in multiple myeloma

Abstract

Drug resistance remains the key problem in cancer treatment. It is now accepted that each myeloma patient harbors multiple subclones and subclone dominance may change over time. The coexistence of multiple subclones with high or low chromosomal instability (CIN) signature causes heterogeneity and drug resistance with consequent disease relapse. In this study, using a tandem affinity purification–mass spectrometry (TAP-MS) technique, we found that NEK2, a CIN gene, was bound to the deubiquitinase USP7. Binding to USP7 prevented NEK2 ubiquitination resulting in NEK2 stabilization. Increased NEK2 kinase levels activated the canonical NF-κB signaling pathway through the PP1α/AKT axis. Newly diagnosed myeloma patients with activated NF-κB signaling through increased NEK2 activity had poorer event-free and overall survivals based on multiple independent clinical cohorts. We also found that NEK2 activated heparanase, a secreted enzyme, responsible for bone destruction in an NF-κB–dependent manner. Intriguingly, both NEK2 and USP7 inhibitors showed great efficacy in inhibiting myeloma cell growth and overcoming NEK2-induced and -acquired drug resistance in xenograft myeloma mouse models.

Authors

Reinaldo Franqui-Machin, Mu Hao, Hua Bai, Zhimin Gu, Xin Zhan, Hasem Habelhah, Yogesh Jethava, Lugui Qiu, Ivana Frech, Guido Tricot, Fenghuang Zhan

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Figure 6

NEK2 regulates heparanase expression via NF-κB.

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NEK2 regulates heparanase expression via NF-κB. (A) Total RNA from EV or...
(A) Total RNA from EV or NEK2-OE or NEK2-shRNA ARP1 cells were harvested for gene expression profiling; NEK2 and HPSE mRNA levels are presented as bar graphs of duplicate samples. (B) The map of p65 binding to the HPSE promoter was obtained from the UCSC genome browser ChIP-seq data (track name: GM12878+TNFa RELA). HSPE contains 2 RELA (p65) binding sites across its sequence. H3K4me3 and H3K27Ac, typical for promoter and activator binding elements, respectively, show strong peaks at the p65 binding site of the HPSE sequence (red box). (C) ChIP-qPCR was performed in control cell (EV) and NEK2-OE ARP1 myeloma cells using p65 antibodies. The DNA occupancy of the HPSE promoter was analyzed by qPCR and a Student’s t test was performed to assess the significance. *P < 0.05. (D) NEK2-OE ARP1 myeloma cells were treated with vehicle or the NF-κB inhibitor BAY11-7082 (BAY). Cell lysates from NEK2-OE ARP1 cells and the control EV ARP1 cells were probed with antibodies against NEK2, p-p65-S536, and HPSE by Western blot.