A role for activated Cdc42 in glioblastoma multiforme invasion

// Hidehiro Okura 1, 2 , Brian J. Golbourn 1 , Uswa Shahzad 1 , Sameer Agnihotri 1 , Nesrin Sabha 7 , Jonathan R. Krieger 8 , Carlyn A. Figueiredo 1 , Alan Chalil 1 , Natalie Landon-Brace 1 , Alexandra Riemenschneider 1 , Hajime Arai 2 , Christian A. Smith 1 , Songli Xu 5 , Stefan Kaluz 4, 6 , Adam I. Marcus 5, 6 , Erwin G. Van Meir 4, 5, 6 , James T. Rutka 1, 3 1 The Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, Toronto, Ontario, M5G 0A4, Canada 2 Department of Neurosurgery, Juntendo University School of Medicine, Bunkyo-ku, Tokyo, Japan 3 Department of Surgery, University of Toronto, Toronto, Ontario, M5T 1P5, Canada 4 Department of Neurosurgery, Emory University School of Medicine, Atlanta, Georgia, 30307, USA 5 Department of Hematology and Medical Oncology, Emory University School of Medicine, Atlanta Georgia, 30307, USA 6 Winship Cancer Institute, Emory University School of Medicine, Atlanta, Georgia, 30307, USA 7 Genetics and Genome Biology, Hospital for Sick Children Research Institute, Toronto, Ontario, M5G 0A4, Canada 8 SPARC Biocentre, The Hospital for Sick Children, Toronto, Ontario, M5G 0A4, Canada Correspondence to: James T. Rutka, email: james.rutka@sickkids.ca Keywords: cdc42, glioblastoma, migration, invasion, IQGAP1 and pFAK Received: February 02, 2016     Accepted: July 18, 2016     Published: July 29, 2016 ABSTRACT Cdc42 is a Rho-GTPase which plays a major role in regulating cell polarity and migration by specifying the localization of filopodia. However, the role of Cdc42 in GBM invasion has not been thoroughly investigated. We generated stable doxycycline-inducible clones expressing wild type (WT)-, constitutively active (CA)-, and dominant negative (DN)-Cdc42 in three different human glioma cell lines. Expression of CA-Cdc42 significantly increased the migration and invasive properties of malignant glioma cells compared to WT and DN-Cdc42 cell clones, and this was accompanied by a greater number of filopodia and focal adhesion structures which co-localize with phosphorylated focal adhesion kinase (FAK). By mass spectrometry and immunoprecipitation studies, we demonstrated that activated Cdc42 binds to IQGAP1. When implanted orthotopically in mice, the CA-Cdc42 expressing glioma cells exhibited enhanced local migration and invasion, and led to larger tumors, which significantly reduced survival. Using the Cancer Genome Atlas dataset, we determined that high Cdc42 expression is associated with poorer progression free survival, and that Cdc42 expression is highest in the proneural and neural subgroups of GBM. In summary, our studies demonstrate that activated Cdc42 is a critical determinant of the migratory and invasive phenotype of malignant gliomas, and that its effect may be mediated, at least in part, through its interaction with IQGAP1 and phosphorylated FAK.