Reduced Contractility and Motility of Prostatic Cancer-Associated Fibroblasts after Inhibition of Heat Shock Protein 90

Alex Henke,Simon Hayward,Omar Franco,Axel Thomson,Antony Riddick,Grant Stewart,Elad Katz

doi:10.3390/cancers8090077

Abstract

Background: Prostate cancer-associated fibroblasts (CAF) can stimulate malignant progression and invasion of prostatic tumour cells via several mechanisms including those active in extracellular matrix; Methods: We isolated CAF from prostate cancer patients of Gleason Score 6–10 and confirmed their cancer-promoting activity using an in vivo tumour reconstitution assay comprised of CAF and BPH1 cells. We tested the effects of heat shock protein 90 (HSP90) inhibitors upon reconstituted tumour growth in vivo. Additionally, CAF contractility was measured in a 3D collagen contraction assay and migration was measured by scratch assay; Results: HSP90 inhibitors dipalmitoyl-radicicol and 17-dimethylaminoethylamino-17-demethoxygeldanamycin (17-DMAG) reduced tumour size and proliferation in CAF/BPH1 reconstituted tumours in vivo. We observed that the most contractile CAF were derived from patients with lower Gleason Score and of younger age compared with the least contractile CAF. HSP90 inhibitors radicicol and 17-DMAG inhibited contractility and reduced the migration of CAF in scratch assays. Intracellular levels of HSP70 and HSP90 were upregulated upon treatment with HSP90 inhibitors. Inhibition of HSP90 also led to a specific increase in transforming growth factor beta 2 (TGFβ2) levels in CAF; Conclusions: We suggest that HSP90 inhibitors act not only upon tumour cells, but also on CAF in the tumour microenvironment.

Highlights

Carcinomas are complex multi-cellular communities, consisting of tumour epithelia, immune cells, stroma, and the surrounding microenvironment
We suggest that some effects of heat shock protein 90 (HSP90) inhibition upon tumour growth in vivo may be mediated via cancer-associated fibroblasts (CAF), in addition to direct effects previously documented upon tumour cells
These studies suggest that inhibition of HSP90 action in CAF can reduce tumour growth, and that these effects are likely in addition to direct effects upon tumour cells themselves

Summary

Introduction

Carcinomas are complex multi-cellular communities, consisting of tumour epithelia, immune cells, stroma, and the surrounding microenvironment. The relationships between these tissues evolves as the tumour progresses from a localized well differentiated lesion to an invasive and less organized structure. CAF communicate with, and regulate the proliferation, of adjacent epithelia via multiple signalling molecules, e.g., CXCL12 and TGFβ [2,3,4] They can modulate the local extracellular matrix by secretion of matrix metalloproteinases (MMP) and deposition of hyaluron and collagen [5], thereby stiffening the tissue. Inhibition of HSP90 led to a specific increase in transforming growth factor beta 2 (TGFβ2) levels in CAF; Conclusions: We suggest that HSP90 inhibitors act upon tumour cells, and on CAF in the tumour microenvironment

Methods

Results

Conclusion