Korelacija ekspresije MYC i MYCN proteina i autofagije u neuroblastnim tumorima dečjeg doba

Abstract

Uvod: Neuroblastni tumori (NT) obuhvataju neuroblastom (NB), ganglioneuroblastom (GNB) i ganglioneurom (GN) i predstavljaju najčešće ekstrakranijalne, solidne tumore dečjeg doba. Autofagija je evolucijski konzerviran subcelularni proces lizozomski zavisne degradacije citoplazmatskog sadržaja pomoću autofagnih vakuola (AV). Autofagija se aktivira u tumorskim ćelijama kao odgovor na različite vrste stresa. Cilj disertacije je da ispita prisustvo autofagije i ekspresiju MYC i MYCN proteina u različitim tipovima neuroblastnih tumora i njihov odnos sa do sada poznatim prognostičkim faktorima. Materijal i metode: Studija je obuhvatila 60 bolesnika sa NT, koji su dijagnostikovani između 1996. i 2015. godine u Odeljenju za kliničku patologiju Instituta za zdravstvenu zaštitu majke i deteta Srbije „Dr Vukan Čupić“. Uzorci tumorskog tkiva su analizirani imunohistohemijski antitelima za MYC, MYCN i LC3B. Fluorescentna in situ hibridizacija (FISH) je korišćena za određivanje MYCN i 1p statusa. Uzorci smrznutog tumorskog tkiva 20 bolesnika su ispitivani transmisionim elektronskim mikroskopom. Rezultati: U studiju je uključeno 36 dečaka i 24 devojčice. Prosečan uzrast bolesnika je bio 36 meseci. Stariji su bili bolesnici sa prognostički povoljnijim tipovima NT (GN i iGNB). Statistički značajno veći broj AV, kao i veća ekspresija LC3B nađeni su u uzorcima NB u poređenju sa GN i iGNB. LC3B ekspresija nije bila u korelaciji ni sa jednim kliničkopatološkim faktorom, niti sa preživljavanjem. Imunohistohemijski viši nivo ekspresije MYCN proteina nađen je u uzorcima NB. Postojala je statistički značajna razlika u preživljavanju između grupe sa visokim i niskim nivoom MYCN proteina. Nije bilo korelacije MYCN ekspresije sa prognostičkim faktorima značajnim za NB. MYC ekspresija je uočena samo u ćelijama krvnih sudova. Zaključak: Dobijeni rezultati ukazuju da agresivni dečji neuroblastom pokazuje značajni porast broja autofagnih vakuola, visok nivo LC3B i MYCN ekspresije i mogli bi predstavljati faktore značajne za razvoj kancera.

Beckground: Neuroblastic tumors (NT) including neuroblastoma (NB), ganglioneuroblastoma (GNB) and ganglioneuroma (GN) are the most common extracranial solid tumors of childhood. Autophagy is an evolutionarily conserved lysosome-dependent subcellular process for degradation of cytoplasmic contents by autophagic vacuoles (AV). Autophagy is activated in cancer cells in response to multiple stresses. The aim of this dissertation was to analyze presents of autophagy and expression of MYC and MYCN protein in different types of neuroblastic tumors, and there relations with known prognostic parameters. Materials and methods: These study included 60 patients with NT who were diagnosed between 1996 and 2015. in the Department of Pathology of Mother and Child Health Care Institute of Serbia „Dr Vukan Čupić“. Tumor tissue samples were analysed immunohistochemically with MYC, MYCN and LC3B antibodys. Fluorescence in situ hybridisation (FISH) had been used to establish MYCN and 1p status. Frozen tumor tissue samples of 20 patients were examined by Transmission Electron Microscopy. Results: Study included 36 males and 24 females, with average age of 36 month. Patients with good prognostic NT types (GN, iGNB) were older. Significantly higher number of AV and higher LC3B expression were found in tissue samples of NB comparing to GN and iGNB. LC3B expression did not correlate with various clinicopathological factors, including overal survival. Immunochistochemically, higher MYCN expression was found in NB samples and was statisticaly significant for survival comparing groups with high and low level of MYCN expression. No correlation with neuroblastoma prognostic factors was found. MYC expression was exclusively found in the blood vessels cells. Conclusions: Our results indicate that aggressive childhood neuroblastomas show massive increase in the number of autophagic vacuoles, high expression of LC3B and MYCN protein and suggest that these factors are advantageous to cancer development.