Rossetti Diana Valeria, Massimi Luca, Martelli Claudia, Vincenzoni Federica, Di Silvestre Susanna, Scorpio Gianluca, Tamburrini Gianpiero, Caldarelli Massimo, Urbani Andrea, Desiderio Claudia
Dipartimento di Scienze biotecnologiche di base, cliniche intensivologiche e perioperatorie, Università Cattolica del Sacro Cuore, 00168 Roma, Italy.
Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Roma, Italy.
Cancers (Basel). 2020 Mar 13;12(3):674. doi: 10.3390/cancers12030674.
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.
小儿室管膜瘤是一种脑肿瘤，在幕上区域的发生率约为10%-15%，在后颅窝区域为20%-30%。这些肿瘤对手术几乎有选择性反应，而对放疗和化疗药物分别有相对且已证实的耐药性。除了组织病理学分级外，室管膜瘤的临床和治疗评估目前还考虑肿瘤定位以及基因组概述的相关分子亚组，如今幕上和后颅窝室管膜瘤被认为是不同的疾病。基于这些原因，并为了更好地了解这些肿瘤的分子特征，本研究旨在通过质谱平台首次研究不同分级和定位的小儿室管膜瘤组织的蛋白质组学图谱，以揭示潜在的不同蛋白质表型。为此，分别采用自上而下和鸟枪法蛋白质组学方法，通过液相色谱-质谱联用分析室管膜瘤肿瘤组织匀浆的酸溶性和酸不溶性部分，以研究完整蛋白质组或其消化形式。这两种方法在分析室管膜瘤肿瘤组织时具有互补性，并显示出幕上和后颅窝室管膜瘤以及世界卫生组织II级和III级肿瘤分级的不同图谱。自上而下的蛋白质组学分析显示，幕上室管膜瘤中胸腺素β4、10 kDa热休克蛋白、非组蛋白染色体蛋白HMG-17以及胶质纤维酸性蛋白（GFAP）片段388-432的单/非瓜氨酸化形式比率在统计学上显著更高；与III级后颅窝室管膜瘤相比，相同的GFAP片段以及血红蛋白α链和β链在II级中更为明显。对已鉴定的癌症和非癌症相关蛋白质的鸟枪法数据进行基因本体分类，揭示了专门标记肿瘤定位和选择性过度表达途径的蛋白质元件。这些结果虽然是初步的，但似乎与不同侵袭性分级和脑区发育的室管膜瘤的不同蛋白质图谱一致，并有助于扩大对这种仍然神秘的肿瘤的分子认识。
