Abstract

Enhancing the efficacy of proteasome inhibitors (PI) is a central goal in myeloma therapy. We proposed that signaling-level responses after PI may reveal new mechanisms of action that can be therapeutically exploited. Unbiased phosphoproteomics after treatment with the PI carfilzomib surprisingly demonstrates the most prominent phosphorylation changes on splicing related proteins. Spliceosome modulation is invisible to RNA or protein abundance alone. Transcriptome analysis after PI demonstrates broad-scale intron retention, suggestive of spliceosome interference, as well as specific alternative splicing of protein homeostasis machinery components. These findings lead us to evaluate direct spliceosome inhibition in myeloma, which synergizes with carfilzomib and shows potent anti-tumor activity. Functional genomics and exome sequencing further support the spliceosome as a specific vulnerability in myeloma. Our results propose splicing interference as an unrecognized modality of PI mechanism, reveal additional modes of spliceosome modulation, and suggest spliceosome targeting as a promising therapeutic strategy in myeloma.

The mechanisms of action of proteasome inhibitors (PI) in multiple myeloma (MM) treatment are not fully elucidated. Here, the authors use unbiased phosphoproteomics in PI-treated MM and show increased phosphorylation of splicing-associated proteins, ultimately revealing splicing interference as a mode of PI action as well as demonstrating the spliceosome as a specific therapeutic vulnerability in this disease.

Details

Title
Proteasome inhibitor-induced modulation reveals the spliceosome as a specific therapeutic vulnerability in multiple myeloma
Author
Huang, Hector H 1   VIAFID ORCID Logo  ; Ferguson, Ian D 1 ; Thornton, Alexis M 2 ; Bastola Prabhakar 1   VIAFID ORCID Logo  ; Lam, Christine 1 ; Lin, Yu-Hsiu T 1   VIAFID ORCID Logo  ; Choudhry Priya 1   VIAFID ORCID Logo  ; Mariano, Margarette C 1 ; Marcoulis, Makeba D 1 ; Teo, Chin Fen 3 ; Malato Julia 4 ; Phojanakong, Paul J 4 ; Martin, Thomas G, III 5 ; Wolf, Jeffrey L 5 ; Wong, Sandy W 5 ; Shah, Nina 5 ; Hann, Byron 4 ; Brooks, Angela N 2   VIAFID ORCID Logo  ; Wiita, Arun P 6   VIAFID ORCID Logo 

 University of California, Department of Laboratory Medicine, San Francisco, USA (GRID:grid.266102.1) (ISNI:0000 0001 2297 6811) 
 University of California, Department of Biomolecular Engineering, Santa Cruz, USA (GRID:grid.205975.c) (ISNI:0000 0001 0740 6917) 
 University of California, Department of Physiology, San Francisco, USA (GRID:grid.266102.1) (ISNI:0000 0001 2297 6811) 
 University of California, Helen Diller Family Comprehensive Cancer Center, San Francisco, USA (GRID:grid.266102.1) (ISNI:0000 0001 2297 6811) 
 University of California, Helen Diller Family Comprehensive Cancer Center, San Francisco, USA (GRID:grid.266102.1) (ISNI:0000 0001 2297 6811); University of California, Department of Medicine, San Francisco, USA (GRID:grid.266102.1) (ISNI:0000 0001 2297 6811) 
 University of California, Department of Laboratory Medicine, San Francisco, USA (GRID:grid.266102.1) (ISNI:0000 0001 2297 6811); University of California, Helen Diller Family Comprehensive Cancer Center, San Francisco, USA (GRID:grid.266102.1) (ISNI:0000 0001 2297 6811) 
Publication year
2020
Publication date
2020
Publisher
Nature Publishing Group
e-ISSN
20411723
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2393614607
Copyright
© The Author(s) 2020. This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.