title: Secreted heat shock protein 90 promotes prostate cancer stem cell heterogeneity.
abstract: Heat-shock protein 90 (Hsp90), a highly conserved molecular chaperone, is frequently upregulated in tumors, and remains an attractive anti-cancer target. Hsp90 is also found extracellularly, particularly in tumor models. Although extracellular Hsp90 (eHsp90) action is not well defined, eHsp90 targeting attenuates tumor invasion and metastasis, supporting its unique role in tumor progression. We herein investigated the potential role of eHsp90 as a modulator of cancer stem-like cells (CSCs) in prostate cancer (PCa). We report a novel function for eHsp90 as a facilitator of PCa stemness, determined by its ability to upregulate stem-like markers, promote self-renewal, and enhance prostasphere growth. Moreover, eHsp90 increased the side population typically correlated with the drug-resistant phenotype. Intriguingly, tumor cells with elevated surface eHsp90 exhibited a marked increase in stem-like markers coincident with increased expression of the epithelial to mesenchymal (EMT) effector Snail, indicating that surface eHsp90 may enrich for a unique CSC population. Our analysis of distinct effectors modulating the eHsp90-dependent CSC phenotyperevealed that eHsp90 is a likely facilitator of stem cell heterogeneity. Taken together, our findings provide unique functional insights into eHsp90 as a modulator of PCa plasticity, and provide a framework towards understanding its role as a driver of tumor progression.
authors.affiliation: Department of Cell and Molecular Pharmacology, Medical University of South Carolina, Hollings Cancer Center, Charleston, SC, USA.
authors.forename: Krystal D
authors.initials: KD
authors.lastname: Nolan
authors.affiliation: Department of Cell and Molecular Pharmacology, Medical University of South Carolina, Hollings Cancer Center, Charleston, SC, USA.
authors.forename: Jasmine
authors.initials: J
authors.lastname: Kaur
authors.affiliation: Department of Cell and Molecular Pharmacology, Medical University of South Carolina, Hollings Cancer Center, Charleston, SC, USA.
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: Isaacs
mesh_terms: D014408:Biomarkers, Tumor / Q000378:metabolism*; D000066673:Cell Self Renewal; D058750:Epithelial-Mesenchymal Transition; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D008297:Male; D014411:Neoplastic Stem Cells / Q000378:metabolism / Q000473:pathology*; D011471:Prostatic Neoplasms / Q000378:metabolism / Q000473:pathology*; D015398:Signal Transduction; D014407:Tumor Cells, Cultured
chemical_list: D014408:Biomarkers, Tumor; D018841:HSP90 Heat-Shock Proteins
keywords: Hsp90; cancer stem cells; epithelial to mesenchymal transition (EMT); prostaspheres