Ependymoma Pediatric Brain Tumor Protein Fingerprinting by Integrated Mass Spectrometry Platforms: A Pilot Investigation

Abstract

Ependymoma pediatric brain tumor occurs at approximate frequencies of 10-15% in supratentorial and 20-30% in posterior fossa regions. These tumors have an almost selective response to surgery and relative and confirmed resistance to radiotherapy and chemotherapic agents, respectively. Alongside histopathological grading, clinical and treatment evaluation of ependymomas currently consider the tumor localization and the genomic outlined associated molecular subgroups, with the supratentorial and the posterior fossa ependymomas nowadays considered diverse diseases. On these grounds and in trying to better understand the molecular features of these tumors, the present investigation aimed to originally investigate the proteomic profile of pediatric ependymoma tissues of different grade and localization by mass spectrometry platforms to disclose potential distinct protein phenotypes. To this purpose, acid-soluble and acid-insoluble fractions of ependymoma tumor tissues homogenates were analyzed by LC-MS following both the top-down and the shotgun proteomic approaches, respectively, to either investigate the intact proteome or its digested form. The two approaches were complementary in profiling the ependymoma tumor tissues and showed distinguished profiles for supratentorial and posterior fossa ependymomas and for WHO II and III tumor grades. Top-down proteomic analysis revealed statistically significant higher levels of thymosin beta 4, 10 kDa heat shock protein, non-histone chromosomal protein HMG-17, and mono-/uncitrullinated forms ratio of the glial fibrillary acidic protein (GFAP) fragment 388-432 in supratentorial ependymomas-the same GFAP fragment as well as the hemoglobin alpha-and the beta-chain marked grade II with respect to grade III posterior fossa ependymomas. Gene ontology classification of shotgun data of the identified cancer and the non-cancer related proteins disclosed protein elements exclusively marking tumor localization and pathways that were selectively overrepresented. These results, although preliminary, seem consistent with different protein profiles of ependymomas of diverse grade of aggressiveness and brain region development and contributed to enlarging the molecular knowledge of this still enigmatic tumor.

Posterior fossa ependymomas in children: still a challenge for pediatric neurosurgeons and oncologists.

“…If it is known a predominance in infancy [16], our series confirm a higher frequency in childhood with 36.4% [17]. A peak between 4 years old and 6 years old has been observed [2]. The male predominance in our series is classic and reported by many authors [6,7,15].…”

“…Ependymoma is the third most common tumor in the posterior fossa in children [7,8]. They account for 20-30% of central nervous system tumors [2,9,10]. In our series, EpPCF account for 78.6% of intracranial ependymomas [7,11,12].…”

“…Ependymomas are classified according the World Health Organization (WHO) as grade II and III [2]. This classification was not correlated to the prognosis.…”

“…Posterior fossa ependymoma (EpPCF) in children have a different behavior from other localizations [1,2] and differ from adult EpPCF [3,4]. A complete removal combined with craniospinal irradiation +/-chemotherapy is the treatment of choice [5,6].…”

Pediatric Brain Tumors: Signatures from the Intact Proteome

“…Therefore, the intact proteome profiles of pediatric brain-tumor tissues of different WHO grades and localization, namely, medulloblastoma (MB), pilocytic astrocytoma (PA), and glioblastoma multiforme (GBM), were compared by label-free LC–MS top-down proteomic analysis to explore qualitative and quantitative variations and to disclose potential signatures and/or biomarkers. The results were also compared with the proteomic data already available on ependymoma [ 9 ], resulting in a total of 50 specimens analyzed.…”