The Urokinase Receptor Induces a Mesenchymal Gene Expression Signature in Glioblastoma Cells and Promotes Tumor Cell Survival in Neurospheres

Andrew S Gilder,Richard L Klemke,Letizia Natali,Michael A Banki,Steven L Gonias,Danielle M Van Dyk,Donald P Pizzo,Elisabetta Mantuano,Cristina Zalfa,Huawei Wang

doi:10.1038/s41598-018-21358-1

Andrew S Gilder, Richard L Klemke + Show 8 more

Open Access

https://doi.org/10.1038/s41598-018-21358-1

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Abstract

PLAUR encodes the urokinase receptor (uPAR), which promotes cell survival, migration, and resistance to targeted cancer therapeutics in glioblastoma cells in culture and in mouse model systems. Herein, we show that patient survival correlates inversely with PLAUR mRNA expression in gliomas of all grades, in glioblastomas, and in the subset of glioblastomas that demonstrate the mesenchymal gene expression signature. PLAUR clusters with genes that define the more aggressive mesenchymal subtype in transcriptome profiles of glioblastoma tissue and glioblastoma cells in neurospheres, which are enriched for multipotent cells with stem cell-like qualities. When PLAUR was over-expressed or silenced in glioblastoma cells, neurosphere growth and expression of mesenchymal subtype biomarkers correlated with uPAR abundance. uPAR also promoted glioblastoma cell survival in neurospheres. Constitutively-active EGF Receptor (EGFRvIII) promoted neurosphere growth; however, unlike uPAR, EGFRvIII did not induce the mesenchymal gene expression signature. Immunohistochemical analysis of human glioblastomas showed that uPAR is typically expressed by a small sub-population of the cancer cells; it is thus reasonable to conclude that this subpopulation of cells is responsible for the effects of PLAUR on patient survival. We propose that uPAR-expressing glioblastoma cells demonstrate a mesenchymal gene signature, an increased capacity for cell survival, and stem cell-like properties.

Highlights

The PLAUR gene product, uPAR, is a glycosyl-phosphatidylinositol-anchored membrane protein that binds the serine proteinase, urokinase-type plasminogen activator, and activates a cascade of extracellular proteinases that function in tissue remodeling[6,7,8]
To identify pathways by which PLAUR gene expression in occasional tumor cells may affect patient survival, we examined glioblastoma cells in neurospheres, which select for multipotent cells with cancer stem cell-like properties[35,36,37]
We showed that uPAR promotes expression of other genes that serve as biomarkers of the mesenchymal glioblastoma subtype. uPAR promoted neurosphere growth and inhibited glioblastoma cell apoptosis in neurospheres

Summary

Introduction

The PLAUR gene product, uPAR, is a glycosyl-phosphatidylinositol-anchored membrane protein that binds the serine proteinase, urokinase-type plasminogen activator (uPA), and activates a cascade of extracellular proteinases that function in tissue remodeling[6,7,8]. PLAUR has been characterized as a gene expressed selectively by mesenchymal glioblastomas[28] This is intriguing because, in cell culture and animal model systems, uPAR promotes glioblastoma cell survival, cell migration, and resistance to targeted cancer therapies[32,33,34]. To identify pathways by which PLAUR gene expression in occasional tumor cells may affect patient survival, we examined glioblastoma cells in neurospheres, which select for multipotent cells with cancer stem cell-like properties[35,36,37]. We propose that PLAUR gene expression in glioblastoma adversely affects patient survival by promoting a mesenchymal gene expression profile, by allowing cell survival, and by inducing stem cell-like properties in a small sub-population of glioblastoma cells

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