Dysregulated fibronectin trafficking by Hsp90 inhibition restricts prostate cancer cell invasion

Heather K Armstrong,Gerard Tarulli,Joanna L Gillis,Douglas A Brooks,Emma S Tomlinson Guns,Mei Yieng Chin,Max Moldovan,Luke A Selth,Margaret M Centenera,Ian R D Johnson,Martin C Sadowski,David J Lynn,Zeyad D Nassar,Claire Levrier,Lisa M Butler

doi:10.1038/s41598-018-19871-4

Abstract

The molecular chaperone Hsp90 is overexpressed in prostate cancer (PCa) and is responsible for the folding, stabilization and maturation of multiple oncoproteins, which are implicated in PCa progression. Compared to first-in-class Hsp90 inhibitors such as 17-allylamino-demethoxygeldanamycin (17-AAG) that were clinically ineffective, second generation inhibitor AUY922 has greater solubility and efficacy. Here, transcriptomic and proteomic analyses of patient-derived PCa explants identified cytoskeletal organization as highly enriched with AUY922 treatment. Validation in PCa cell lines revealed that AUY922 caused marked alterations to cell morphology, and suppressed cell motility and invasion compared to vehicle or 17-AAG, concomitant with dysregulation of key extracellular matrix proteins such as fibronectin (FN1). Interestingly, while the expression of FN1 was increased by AUY922, FN1 secretion was significantly decreased. This resulted in cytosolic accumulation of FN1 protein within late endosomes, suggesting that AUY922 disrupts vesicular secretory trafficking pathways. Depletion of FN1 by siRNA knockdown markedly reduced the invasive capacity of PCa cells, phenocopying AUY922. These results highlight a novel mechanism of action for AUY922 beyond its established effects on cellular mitosis and survival and, furthermore, identifies extracellular matrix cargo delivery as a potential therapeutic target for the treatment of aggressive PCa.

Highlights

Prostate cancer (PCa) is the second leading cause of cancer-related deaths, and the most commonly diagnosed malignancy in Western men[1,2]
RNA-seq analysis identified 1698 differentially expressed genes (DEGs; p < 0.05) in AUY922 treated PDEs compared with vehicle treatment and 715 DEGs (p < 0.05) compared to 17-AAG treated PDEs, see Supplementary Dataset for Differential expression (DE) analysis outcomes
Proteins of interest were those that were differentially expressed in AUY922 treated PDEs compared with both vehicle and 17-AAG, resulting in 26 proteins spots being subjected to identification by mass spectrometry

Summary

Introduction

Prostate cancer (PCa) is the second leading cause of cancer-related deaths, and the most commonly diagnosed malignancy in Western men[1,2]. As many Hsp[90] clients are known oncoproteins, cancer cells have a greater dependence on Hsp[90] for growth and survival compared to non-malignant cells[10,11,12]. This dependence is further exacerbated by the increased number of mutated or misfolded proteins known to accumulate within cancer cells, as these are www.nature.com/scientificreports/. Using patient-derived prostate tumor tissues, cultured as explants, we previously demonstrated that AUY922 has greater biological activity than 17-AAG in terms of reducing tumor cell proliferation and inducing apoptosis[16]. This study identified pathways selectively altered by AUY922, and not 17-AAG, in patient-derived PCa explants and further interrogated the influence of those pathways on the anti-tumor activity of AUY922

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