iTRAQ-based Proteomics Profiling Reveals Increased Metabolic Activity and Cellular Cross-talk in Angiogenic Compared with Invasive Glioblastoma Phenotype

doi:10.1074/mcp.M900124-MCP200

HOME

HELP

FEEDBACK

SUBSCRIPTIONS

Research

iTRAQ-based Proteomics Profiling Reveals Increased Metabolic Activity and Cellular Cross-talk in Angiogenic Compared with Invasive Glioblastoma Phenotype^*^,

Uros Rajcevic, Kjell Petersen, Jaco C. Knol^¶, Maarten Loos^||, Sébastien Bougnaud, Oleg Klychnikov^||, Ka Wan Li^||, Thang V. Pham^¶, Jian Wang^**, Hrvoje Miletic^**, Zhao Peng^**, Rolf Bjerkvig^,**, Connie R. Jimenez^¶ and Simone P. Niclou^,

From the ${ddagger}$ Norlux Neuro-Oncology Laboratory, Department of Oncology, Centre de Recherche Public Santé (CRP-Santé), 84 Val Fleuri, L-1526 Luxembourg, Luxembourg,
$§$ Computational Biology Unit, Bergen Center for Computational Science, University of Bergen, Thormøhlensgt 55, N-5008 Bergen, Norway,
¶OncoProteomics Laboratory, Department of Medical Oncology, Vrije Universiteit (VU) Medical Cancer Center, De Boelelaan 1117, NL-1081 HV Amsterdam, The Netherlands,
||Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, VU Amsterdam, De Boelelaan 1085, NL-1081 HV Amsterdam, The Netherlands,
**Norlux Neuro-Oncology, Department of Biomedicine, University of Bergen , Jonas Lies Vei 91, N-5009 Bergen, Norway

Malignant gliomas (glioblastoma multiforme) have a poor prognosiswith an average patient survival under current treatment regimensranging between 12 and 14 months. The tumors are characterizedby rapid cell growth, extensive neovascularization, and diffusecellular infiltration of normal brain structures. We have developeda human glioblastoma xenograft model in nude rats that is characterizedby a highly infiltrative non-angiogenic phenotype. Upon serialtransplantation this phenotype will develop into a highly angiogenictumor. Thus, we have developed an animal model where we areable to establish two characteristic tumor phenotypes that definehuman glioblastoma (i.e. diffuse infiltration and high neovascularization).Here we aimed at identifying potential biomarkers expressedby the non-angiogenic and the angiogenic phenotypes and elucidatingthe molecular pathways involved in the switch from invasiveto angiogenic growth. Focusing on membrane-associated proteins,we profiled protein expression during the progression from aninvasive to an angiogenic phenotype by analyzing serially transplantedglioma xenografts in rats. Applying isobaric peptide taggingchemistry (iTRAQ) combined with two-dimensional LC and MALDI-TOF/TOFmass spectrometry, we were able to identify several thousandproteins in membrane-enriched fractions of which 1460 were extractedas quantifiable proteins (isoform- and species-specific andpresent in more than one sample). Known and novel candidateproteins were identified that characterize the switch from anon-angiogenic to a highly angiogenic phenotype. The robustnessof the data was corroborated by extensive bioinformatics analysisand by validation of selected proteins on tissue microarraysfrom xenograft and clinical gliomas. The data point to enhancedintercellular cross-talk and metabolic activity adopted by tumorcells in the angiogenic compared with the non-angiogenic phenotype.In conclusion, we describe molecular profiles that reflect thechange from an invasive to an angiogenic brain tumor phenotype.The identified proteins could be further exploited as biomarkersor therapeutic targets for malignant gliomas.

${ddagger}$ ${ddagger}$ To whom correspondence should be addressed: Norlux Neuro-Oncology Laboratory, CRP-Santé, 84 Val Fleuri, L-1526 Luxembourg, Luxembourg. E-mail: simone.niclou{at}crp-sante.lu.