p53 Function Is Compromised by Inhibitor 2 of Phosphatase 2A in Sonic Hedgehog Medulloblastoma.
Mol Cancer Res
; 17(1): 186-198, 2019 01.
Article
em En
| MEDLINE
| ID: mdl-30224541
ABSTRACT
Medulloblastomas, the most common malignant pediatric brain tumors, have been genetically defined into four subclasses, namely WNT-activated, Sonic Hedgehog (SHH)-activated, Group 3, and Group 4. Approximately 30% of medulloblastomas have aberrant SHH signaling and thus are referred to as SHH-activated medulloblastoma. The tumor suppressor gene TP53 has been recently recognized as a prognostic marker for patients with SHH-activated medulloblastoma; patients with mutant TP53 have a significantly worse outcome than those with wild-type TP53. It remains unknown whether p53 activity is impaired in SHH-activated, wild-type TP53 medulloblastoma, which is about 80% of the SHH-activated medulloblastomas. Utilizing the homozygous NeuroD2SmoA1 mouse model with wild-type Trp53, which recapitulates human SHH-activated medulloblastoma, it was discovered that the endogenous Inhibitor 2 of Protein Phosphatase 2A (SET/I2PP2A) suppresses p53 function by promoting accumulation of phospho-MDM2 (S166), an active form of MDM2 that negatively regulates p53. Knockdown of I2PP2A in SmoA1 primary medulloblastoma cells reduced viability and proliferation in a p53-dependent manner, indicating the oncogenic role of I2PP2A. Importantly, this mechanism is conserved in the human medulloblastoma cell line ONS76 with wild-type TP53. Taken together, these findings indicate that p53 activity is inhibited by I2PP2A upstream of PP2A in SHH-activated and TP53-wildtype medulloblastomas. IMPLICATIONS This study suggests that I2PP2A represents a novel therapeutic option and its targeting could improve the effectiveness of current therapeutic regimens for SHH-activated or other subclasses of medulloblastoma with wild-type TP53.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Neoplasias Cerebelares
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Proteína Supressora de Tumor p53
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Proteínas de Ligação a DNA
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Proteínas Hedgehog
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Chaperonas de Histonas
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Meduloblastoma
Tipo de estudo:
Prognostic_studies
Limite:
Adult
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Animals
/
Humans
Idioma:
En
Revista:
Mol Cancer Res
Assunto da revista:
BIOLOGIA MOLECULAR
/
NEOPLASIAS
Ano de publicação:
2019
Tipo de documento:
Article
País de afiliação:
Geórgia