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Background: Medulloblastoma (MB) is an aggressive pediatric tumor of the Central Nervous System (CNS) usually treated according to a refined risk stratification. The study of cancer stem cells (CSC) in MB is a promising approach aimed at finding new treatment strategies., Methodology/principal Findings: The CSC compartment was studied in three characterized MB cell lines (DAOY, UW228 and ONS-76) grown in standard adhesion as well as being grown as spheres, which enables expansion of the CSC population. MB cell lines, grown in adherence and as spheres, were subjected to morphologic analysis at the light and electron microscopic level, as well as cytofluorimetric determinations. Medullospheres (MBS) were shown to express increasingly immature features, along with the stem cells markers: CD133, Nestin and β-catenin. Proteomic analysis highlighted the differences between MB cell lines, demonstrating a unique protein profile for each cell line, and minor differences when grown as spheres. In MBS, MALDI-TOF also identified some proteins, that have been linked to tumor progression and resistance, such as Nucleophosmin (NPM). In addition, immunocytochemistry detected Sox-2 as a stemness marker of MBS, as well as confirming high NPM expression., Conclusions/significance: Culture conditioning based on low attachment flasks and specialized medium may provide new data on the staminal compartment of CNS tumors, although a proteomic profile of CSC is still elusive for MB.

Objective: The purpose of this study is to detect different protein profiles in medulloblastoma (MDB) that may be clinically relevant and to check the correspondence of histological classification of MDB with proteomic profiles., Materials and Methods: Surgical specimens, snap frozen at the time of neurosurgery, entered the proteomic study. Eight samples from patients (age range, 4 months-26 years) with different MDB histotypes (five classic, one desmoplastic/nodular, one with extensive nodularity, and one anaplastic) were analyzed by two-dimensional gel electrophoresis. One sample for each histotype was further characterized by matrix-assisted laser desorption/ionization time of flight mass spectrometry analysis., Results: Eighty-six unique proteins were identified and compared to histology, with the determination of proteins expressed by single histotypes and of a smaller number of proteins shared by two or three histotypes. The sharp difference of protein expression was found to be in agreement with WHO histological classification, with the identification of type-specific proteins with limited overlapping between histotypes., Conclusion: Proteomic analysis confirmed and strengthened the difference between histotypes as biologically relevant. Cluster analysis enhanced the distance of extensive nodularity MDB from other histotypes. Possible innovative approaches to therapy may rely upon a proteomic-based classification of MDB tightly correlated to histology. The utility of snap freezing tumoral samples must be stressed and should become a mandatory task for pathologists.

We present the case of a 6-year-old male affected by an infratentorial tumor. Histological diagnosis was melanotic medulloblastoma. Immunohistochemistry showed in the melanin rich areas positive cells for HMB45. We performed a proteomic study to compare protein profiles in melanotic versus non-melanotic areas. Protein profiles of different areas of the tumor displayed similarity, with the exception of seven proteins. In accordance with the hypothesis that melanotic medulloblastomas produce oculo-cutaneous melanin, proteomic analysis showed melanocytic-associated antigens and epidermal autoantigen 450K in the pigmented nodule; both these proteins have a significant role as markers of melanotic elements., ((c) 2008 Wiley-Liss, Inc.)