Comprehensive proteomic profiling of bevacizumab-resistant glioblastoma

Neuro-Oncology 16:ii1 – ii112, 2014. doi:10.1093/neuonc/nou174

NEURO-ONCOLOGY Abstracts

Drugs that impair tumour angiogenesis, i.e. therapeutic antibody antivascular endothelial growth factor, bevacizumab (BEV), are becoming standard therapy for recurrent GBM, despite having no impact on overall survival times. Resistance to BEV is fatal, and mechanisms are largely unexplored.

Published by Oxford University Press on behalf of the Society for Neuro-Oncology 2014.

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P17.47. COMPREHENSIVE PROTEOMIC PROFILING OF BEVACIZUMAB-RESISTANT GLIOBLASTOMA MULTIFORME K.L. Kaufman1, L. Ly1, M. McKay2, D.M. Mallawaaratchy3, S. Mactier3, B. Crossett1, M. Molloy2, M.E. Buckland4, K.L. McDonald5, and R.I. Christopherson3; 1The University of Sydney, Camperdown, Australia; 2 Macquarie University, North Ryde, Australia; 3The University of Sydney, Darlington, Australia; 4Royal Prince Alfred Hospital, Camperdown, Australia; 5The University of New South Wales, Randwick, Australia

With access to exceedingly rare fresh-frozen serial GBM tumours, we performed comprehensive quantitative proteome analyses to identify important mechanisms of BEV escape and tumour recurrence. Tumour tissues from three patients [primary (n ¼ 2), recurrent (n ¼ 2) and post-BEV recurrent (n ¼ 3)] were homogenised, clarified (1,000 x g, 48C) and ultracentrifuged (100,000 x g, 48C) to isolate the soluble (SOL) proteome supernatant from the microsomal (MEM) pellet. Digested SOL and MEM proteomes were analysed by two independent quantitative MS/MS approaches; Label-free quantitation performed on spectra obtained in triplicate using an Orbitrap Velos (Thermo Electron) and 4-plex iTRAQ-labelling coupled ERLIC-RP MS/MS analysis using a 5600 TripleTOFw (AB Sciex; single run for MEM; duplicate run for SOL). Spectra were processed using Mascot Distiller, Progenesis, Scaffold and ProteinPilotTM softwares. This multi-centre proteomics project has achieved a number of highly reproducible and comprehensive quantitative proteome datasets (average of 1760 MEM proteins and 2334 SOL proteins identified at 95% confidence levels) from precious serial GBM specimens. Significant differentially abundant proteins include those involved in Rho regulation of actin-based motility and cytoskeleton and endocytosis signalling. Bioinformatics analyses with captured whole exome sequencing data are underway to define novel mechanisms of evasive resistance to BEV in recurrent GBM.