Analysis of phosphotyroisine-containing proteins related to the malignancy in gliomas by proteomic differential display

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Gliomas are the most common of the primary intracranial tumors. Using clinically and histologically assessed various grade of gliomas, we have studied their phosphoprotein profiles by a two-dimensional gel electrophoresis-mass spectrometry approach and identified differentially expressed phosphoproteins which may be useful molecular indicators to understand these progression. Examination of the phosphoprotein profiles of glioma samples of different grades from same patient or different grades from different patients revealed about 40 distinct, differentially expressed phosphoproteins during glioma progression. These phosphoproteins of interest were picked, in-gel digested and mass spectrometry fingerprinted. Some of them were identified successfully. These phosphoproteins belonging to various functional groups such as cytoskeleton and intermediate filament proteins, heat shock proteins, enzymes and regulatory proteins. Some were found to be differentially expressed in both Grade III and glioblastoma multiform (GBM) while others were associated with a particular grade. Several proteins had been reported previously as differentially expressed in human brain cancer in non-phosphorylated form. A notable observation was that prohibitin, a potential tumor suppressor protein, and HSPs as well as glial fibrillary acidic protein (GFAP), major protein of the glial filaments were phosphorylated in both grade III and GBM tumors. We attempt to explain glioma malignancy and progression in terms of their combined role. Albumin, peroxiredoxin 1, aldolase C fructose-biphosphate, creatine kinase, hnRNPs, ATP-dependent DNA helicase were up regulated in GBM versus non-tumor tissues. These differentially expressed proteins provided novel information on the differences existing between normal brain and gliomas, and thus might prove to be useful molecular indicators of diagnostic or prognostic value.