Merlin Knockdown in Human Schwann Cells
- 1 April 2010
- journal article
- tumors of-the-ear-and-cranial-base
- Published by Ovid Technologies (Wolters Kluwer Health) in Otology & Neurotology
- Vol. 31 (3), 460-466
- https://doi.org/10.1097/mao.0b013e3181d2777f
Abstract
Hypothesis: To investigate the early events in molecular progression toward schwannoma tumorigenesis, we developed an in vitro model of human Schwann cell tumorigenesis by merlin knockdown. Background: Neurofibromatosis 2 (NF2)-related and sporadic vestibular schwannoma (VS) exhibit loss of functional merlin (schwannomin). After loss of merlin expression in the Schwann cell, the initial steps toward VS tumorigenesis are unknown. Merlin, a putative tumor suppressor protein, interacts with many cellular proteins, regulating their function. Among these are receptor tyrosine kinases, including the epidermal growth factor receptor family B (ErbB) family receptors epidermal growth factor receptor and ErbB2. Functional merlin interacts with and internalizes these growth factor receptors, silencing their proliferation and survival signaling. Deregulation of CD44, the cell adhesion/signaling molecule and cancer stem cell marker, has also been implicated in VS tumorigenesis. Methods: Merlin knockdown was performed using small interfering RNA transfection into human Schwann cell primary cultures. Knockdown was confirmed by real-time quantitative PCR, immunofluorescence, and Western analysis. Expression profiles of ErbB, merlin, and the stem cell markers nestin and CD44 were examined in knockdowns. Proliferation rate was assessed with bromodeoxyuridine incorporation, and radiation sensitivity was assessed using the Annexin assay in knockdowns versus controls. Results: Merlin knockdowns demonstrated increased proliferation rate, upregulation of epidermal growth factor receptor, ErbB2, and ErbB3, CD44, and nestin. Short-term merlin depletion had no effect on γ irradiation sensitivity compared with controls. Conclusion: Merlin depletion results in deregulation of ErbB receptor signaling, promotes a dedifferentiated state, and increases Schwann cell proliferation, suggesting critical steps toward schwannoma tumorigenesis.Keywords
This publication has 20 references indexed in Scilit:
- Merlin regulates transmembrane receptor accumulation and signaling at the plasma membrane in primary mouse Schwann cells and in human schwannomasOncogene, 2008
- Localization to the Cortical Cytoskeleton Is Necessary for Nf2/Merlin-Dependent Epidermal Growth Factor Receptor SilencingMolecular and Cellular Biology, 2008
- Contact-dependent inhibition of EGFR signaling by Nf2/MerlinThe Journal of cell biology, 2007
- Controversies in building a management algorithm for vestibular schwannomasCurrent Opinion in Otolaryngology & Head and Neck Surgery, 2006
- Constitutive neuregulin‐1/ErbB signaling contributes to human vestibular schwannoma proliferationGlia, 2006
- Membrane organization and tumorigenesis—the NF2 tumor suppressor, MerlinGenes & Development, 2005
- Paxillin binds schwannomin and regulates its density-dependent localization and effect on cell morphologyNature Genetics, 2002
- The neurofibromatosis type 2 gene is inactivated in schwannomasHuman Molecular Genetics, 1994
- Alteration in a new gene encoding a putative membrane-organizing protein causes neuro-fibromatosis type 2Nature, 1993
- Loss of genes on chromosome 22 in tumorigenesis of human acoustic neuromaNature, 1986