Proteomic Study of Pilocytic Astrocytoma Pediatric Brain Tumor Intracystic Fluid

Liquid chromatography in coupling with high-resolution ESI-LTQ-Orbitrap mass spectrometry was applied for a proteomic study of pediatric pilocytic astrocytoma brain tumor intracystic fluid by an integrated top-down/bottom-up platform. Both of the proteomic strategies resulted comple-mentary and support each other in contributing to a wide characterization of the protein and peptide content of the tumorfluid. Top-down approach allowed to identify several proteins and peptides involved in different biological activities together with the characterization of interesting proteoforms such as fibrinopeptide A and its truncated form,fibrinopeptide B, complement C3f fragments,?-thymosin peptides, ubiquitin,several apolipoproteins belonging to A and C families,apolipoprotein J and D, and cystatin C. Of particular interest resulted the identification of a N-terminal truncated cystatin C proteoform, likely involved in immune response mechanism modulations and the identification of oxidized and glycosylated apolipoproteins including disulfie bridge dimeric forms. The bottom-up approach confirmed some of the experimental datafindingstogether with adding the characterization of high-molecular-mass proteins in the samples. These data could contribute toelucidate the molecular mechanisms involved in onset and progression of the disease and cyst development.