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Na,K-ATPase β(1)-subunit is a target of sonic hedgehog signaling and enhances medulloblastoma tumorigenicity

BACKGROUND: The Sonic hedgehog (Shh) signaling pathway plays an important role in cerebellar development, and mutations leading to hyperactive Shh signaling have been associated with certain forms of medulloblastoma, a common form of pediatric brain cancer. While the fundamentals of this pathway are...

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Detalles Bibliográficos
Autores principales: Lee, Seung Joon, Litan, Alisa, Li, Zhiqin, Graves, Bruce, Lindsey, Stephan, Barwe, Sonali P., Langhans, Sigrid A.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2015
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4544806/
https://www.ncbi.nlm.nih.gov/pubmed/26286140
http://dx.doi.org/10.1186/s12943-015-0430-1
Descripción
Sumario:BACKGROUND: The Sonic hedgehog (Shh) signaling pathway plays an important role in cerebellar development, and mutations leading to hyperactive Shh signaling have been associated with certain forms of medulloblastoma, a common form of pediatric brain cancer. While the fundamentals of this pathway are known, the molecular targets contributing to Shh-mediated proliferation and transformation are still poorly understood. Na,K-ATPase is a ubiquitous enzyme that maintains intracellular ion homeostasis and functions as a signaling scaffold and a cell adhesion molecule. Changes in Na,K-ATPase function and subunit expression have been reported in several cancers and loss of the β(1)-subunit has been associated with a poorly differentiated phenotype in carcinoma but its role in medulloblastoma progression is not known. METHODS: Human medulloblastoma cell lines and primary cultures of cerebellar granule cell precursors (CGP) were used to determine whether Shh regulates Na,K-ATPase expression. Smo/Smo medulloblastoma were used to assess the Na,K-ATPase levels in vivo. Na,K-ATPase β(1)-subunit was knocked down in DAOY cells to test its role in medulloblastoma cell proliferation and tumorigenicity. RESULTS: Na,K-ATPase β(1)-subunit levels increased with differentiation in normal CGP cells. Activation of Shh signaling resulted in reduced β(1)-subunit mRNA and protein levels and was mimicked by overexpression of Gli1and Bmi1, both members of the Shh signaling cascade; overexpression of Bmi1 reduced β(1)-subunit promoter activity. In human medulloblastoma cells, low β(1)-subunit levels were associated with increased cell proliferation and in vivo tumorigenesis. CONCLUSIONS: Na,K-ATPase β(1)-subunit is a target of the Shh signaling pathway and loss of β(1)-subunit expression may contribute to tumor development and progression not only in carcinoma but also in medulloblastoma, a tumor of neuronal origin.