Novel carfilzomib-based combinations as potential therapeutic strategies for liposarcomas

Maya Jeitany,Deepika Kanojia,Dennis Kappei,H Phillip Koeffler,Vikas Madan,Aishvaryaa Prabhu,Elina Pathak,Yan Yi Jiang,Vineeth Mukundan,Pushkar Dakle,Wai Leong Tam,Yosef Landesman

doi:10.1007/s00018-020-03620-w

Abstract

Proteasome inhibitors, such as bortezomib and carfilzomib, have shown efficacy in anti-cancer therapy in hematological diseases but not in solid cancers. Here, we found that liposarcomas (LPS) are susceptible to proteasome inhibition, and identified drugs that synergize with carfilzomib, such as selinexor, an inhibitor of XPO1-mediated nuclear export. Through quantitative nuclear protein profiling and phospho-kinase arrays, we identified potential mode of actions of this combination, including interference with ribosome biogenesis and inhibition of pro-survival kinase PRAS40. Furthermore, by assessing global protein levels changes, FADS2, a key enzyme regulating fatty acids synthesis, was found down-regulated after proteasome inhibition. Interestingly, SC26196, an inhibitor of FADS2, synergized with carfilzomib. Finally, to identify further combinational options, we performed high-throughput drug screening and uncovered novel drug interactions with carfilzomib. For instance, cyclosporin A, a known immunosuppressive agent, enhanced carfilzomib’s efficacy in vitro and in vivo. Altogether, these results demonstrate that carfilzomib and its combinations could be repurposed for LPS clinical management.

Highlights

The ubiquitin-proteasome system (UPS) is a component that precisely controls the turnover of the majority of proteins [1], making it a critical regulator of numerous cellular pathways
We examined the sensitivity of cancer cell lines to bortezomib in the Cancer Therapeutics Response Portal (CTRP; http://www.broadinstitute.org/ctrp)
We recently assessed the effects of 120 drugs on the viability of liposarcoma cell lines covering the major subtypes of LPS [18]

Summary

Introduction

The ubiquitin-proteasome system (UPS) is a component that precisely controls the turnover of the majority of proteins [1], making it a critical regulator of numerous cellular pathways. Several pharmacological agents have been developed to target the UPS, including bortezomib and carfilzomib, which inhibit the 20S catalytic core of the proteasome. To identify further effective drug combinations, we comprehensively profiled changes in the proteomic landscape after proteasome inhibition. Based on these changes, we demonstrate that combining carfilzomib with an inhibitor of FADS2 synergistically reduces the viability of LPS cells. SILAC labeled cells were treated for 24 h with selinexor (60 nM) and carfilzomib (15 nM) and nuclear proteins were extracted using Nuclear and Cytoplasmic Protein Extraction Kit (Chongqing Bioseps). For PI-induced proteome changes studies, labeled cells were treated with carfilzomib (80 nM) or bortezomib (40 nM) and proteins were extracted with RIPA buffer (Thermo Fisher Scientific). Luminescence was measured with an Infinite M1000 Pro Microplate Reader (Tecan)

Results

Discussion

Compliance with ethical standards