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Allosteric HSP70 inhibitors perturb mitochondrial proteostasis and overcome proteasome inhibitor resistance in multiple myeloma

ABSTRACT: Proteasome inhibitor (PI) resistance remains a central challenge in multiple myeloma. To identify pathways mediating this resistance, we mapped genetic co-dependencies associated with the proteasome. These studies identified cytosolic heat shock protein 70 (HSP70) chaperones as a potential target, mirroring recent studies that have shown mechanism of overcoming PI-induced stress. Here, we first underscore this relationship by mapping genetic co-dependencies in cancer proteostasis. These results lead us to explore HSP70 inhibitors as potential therapeutics. We show these compounds exhibit increased efficacy against both acquired and intrinsic PI-resistant myeloma models, unlike HSP90 inhibition. Surprisingly, shotgun and pulsed-SILAC proteomics reveal that JG’s overcome PI resistance not via the expected mechanism of inhibiting cytosolic HSP70s, but instead through mitochondrial-localized HSP70, HSPA9, destabilizing the 55S mitoribosome. Analysis of myeloma patient data further supports strong effects of global proteostasis capacity, and particularly HSPA9 expression, on response to PI. Our results characterize dynamics of myeloma proteostasis networks under therapeutic pressure while further motivating investigation of HSPA9 as a specific target in PI-resistant disease. This dataset corresponds to figure 5, experiment outlined in figure 5a.

INSTRUMENT(S): Orbitrap Fusion Lumos

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): B Cell, Cell Suspension Culture, Cell Culture

DISEASE(S): Multiple Myeloma

SUBMITTER: Ian Ferguson

LAB HEAD: Arun Wiita

PROVIDER: PXD018387 | Pride | 2020-04-24

REPOSITORIES: Pride

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			Action	DRS
	OxidationMSites.txt	Txt
	Swiss-prot-reviewed.fasta	Fasta
	Z20181031-15.raw	Raw
	Z20181031-16.raw	Raw
	Z20181031-17.raw	Raw

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Allosteric HSP70 inhibitors perturb mitochondrial proteostasis and overcome proteasome inhibitor resistance in multiple myeloma, dataset 2

Project description:Proteasome inhibitor (PI) resistance remains a central challenge in multiple myeloma. To identify pathways mediating this resistance, we mapped genetic co-dependencies associated with the proteasome. These studies identified cytosolic heat shock protein 70 (HSP70) chaperones as a potential target, mirroring recent studies that have shown mechanism of overcoming PI-induced stress. Here, we first underscore this relationship by mapping genetic co-dependencies in cancer proteostasis. These results lead us to explore HSP70 inhibitors as potential therapeutics. We show these compounds exhibit increased efficacy against both acquired and intrinsic PI-resistant myeloma models, unlike HSP90 inhibition. Surprisingly, shotgun and pulsed-SILAC proteomics reveal that JG’s overcome PI resistance not via the expected mechanism of inhibiting cytosolic HSP70s, but instead through mitochondrial-localized HSP70, HSPA9, destabilizing the 55S mitoribosome. Analysis of myeloma patient data further supports strong effects of global proteostasis capacity, and particularly HSPA9 expression, on response to PI. Our results characterize dynamics of myeloma proteostasis networks under therapeutic pressure while further motivating investigation of HSPA9 as a specific target in PI-resistant disease. This dataset corresponds to experiment outlined in figure 4a.

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Allosteric HSP70 inhibitors in Proteasome Inhibitor Resistant Multiple Myeloma

Project description:Proteasome inhibitor (PI) resistance remains a central challenge in multiple myeloma. To identify pathways mediating resistance, we first mapped proteasome-associated genetic co-dependencies. We identified cytosolic heat shock protein 70 (HSP70) chaperones as potential targets, consistent with proposed mechanisms of myeloma tumor cells overcoming PI-induced stress. These results led us to explore allosteric HSP70 inhibitors (JG compounds) as myeloma therapeutics. We showed these compounds exhibit increased efficacy against acquired and intrinsic PI-resistant myeloma models, unlike HSP90 inhibition. Surprisingly, shotgun and pulsed-SILAC mass spectrometry found that JGs have the most pronounced effect on the proteome not through inhibiting cytosolic HSP70s but instead through mitochondrial-localized HSP70, HSPA9/mortalin, destabilizing the 55S mitoribosome. Analysis of myeloma patient data further supports strong effects of global proteostasis capacity, and particularly HSPA9 expression, on PI response. Our results characterize myeloma proteostasis networks under therapeutic pressure while motivating further investigation of HSPA9 as a specific vulnerability in PI-resistant disease.

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Allosteric HSP70 inhibitors perturb mitochondrial proteostasis and overcome proteasome inhibitor resistance in multiple myeloma

Project description:Proteasome inhibitor (PI) resistance remains a central challenge in multiple myeloma. To identify pathways mediating resistance, we first map proteasome-associated genetic co-dependencies. We identify cytosolic heat shock protein 70 (HSP70) chaperones as a potential target, consistent with proposed mechanisms of myeloma tumor cells overcoming PI-induced stress. These results led us to explore allosteric HSP70 inhibitors as myeloma therapeutics. We show these compounds exhibit increased efficacy against both acquired and intrinsic PI-resistant myeloma models, unlike HSP90 inhibition. Surprisingly, shotgun and pulsed-SILAC proteomics reveal that JG’s overcome PI resistance not via the expected mechanism of inhibiting cytosolic HSP70s, but instead through mitochondrial-localized HSP70, HSPA9, destabilizing the 55S mitoribosome. Analysis of myeloma patient data further supports strong effects of global proteostasis capacity, and particularly HSPA9 expression, on PI response. Our results characterize dynamics of myeloma proteostasis networks under therapeutic pressure while further motivating investigation of HSPA9 as a specific target in PI-resistant disease.

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