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Telomere elongation via alternative lengthening of telomeres (ALT) and telomerase activation in primary metastatic medulloblastoma of childhood.

Abstract：

PURPOSE:Elongation of telomeres is necessary for tumor cell immortalization and senescence escape; neoplastic cells use to alternative pathways to elongate telomeres: telomerase reactivation or a telomerase-independent mechanism termed alternative lengthening of telomeres (ALT). Telomerase and ALT pathway has been explored in adult and pediatric gliomas and medulloblastomas (MDBs); however, these mechanisms were not previously investigated in MDBs metastatic at the onset. Therefore, we analyzed the activation of telomerase and ALT pathway in a homogenous cohort of 43 pediatric metastatic medulloblastomas, to investigate whether telomere elongation could play a role in the biology of metastatic MDB. METHODS:We evaluated telomeres length via telomere-specific fluorescence in situ hybridization (Telo-FISH); we assessed nuclear expression of ATRX by immunohistochemistry (IHC). H3F3A and TERT promoter mutations were analyzed by pyrosequencing, while UTSS methylation status was analyzed via methylation-specific-PCR (MS-PCR). RESULTS:H3F3A mutations were absent in all MDBs, 30% of samples showed ATRX nuclear loss, 18.2% of cases were characterized by TERT promoter mutations, while 60.9% harboured TERT promoter hyper-methylation in the UTSS region. Elongation of telomeres was found in 42.8% of cases. Metastatic MDBs control telomere elongation via telomerase activation (10.7%), induced by TERT promoter mutations in association with UTSS hyper-methylation, and ALT mechanism (32.1%), triggered by ATRX inactivation. Among non-metastatic MDBs, only 5.9% (1/17) showed ATRX nuclear loss with activation of ALT. CONCLUSIONS:Our metastatic cases frequently activate ALT pathway, suggesting that it is a common process for senescence escape in primary metastatic medulloblastomas. Furthermore, the activation of mechanisms for telomere elongation is not restricted to certain molecular subgroups in this high-risk group of MDBs.

journal_name

J Neurooncol

journal_title

Journal of neuro-oncology

authors

Minasi S,Baldi C,Pietsch T,Donofrio V,Pollo B,Antonelli M,Massimino M,Giangaspero F,Buttarelli FR

doi

10.1007/s11060-019-03127-w

subject

Has Abstract

pub_date

2019-05-01 00:00:00

pages

435-444

issue

eissn

0167-594X

issn

1573-7373

pii

10.1007/s11060-019-03127-w

journal_volume

142

pub_type

杂志文章

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Telomere elongation via alternative lengthening of telomeres (ALT) and telomerase activation in primary metastatic medulloblastoma of childhood.