Loss of IGFBP7 expression and persistent AKT activation contribute to SMARCB1/Snf5-mediated tumorigenesis
| Autor: | Jonatan Darr, Agnes Klochendler, Sara Isaac, Amir Eden |
|---|---|
| Rok vydání: | 2013 |
| Předmět: |
Male
Cancer Research Programmed cell death IGFBP7 Carcinogenesis Chromosomal Proteins Non-Histone Mice SCID Biology medicine.disease_cause Chromatin remodeling Mice Cell Line Tumor Cell Adhesion Genetics medicine Animals SMARCB1 Cell adhesion Molecular Biology Protein kinase B Rhabdoid Tumor PI3K/AKT/mTOR pathway Mice Knockout Gene Expression Profiling SMARCB1 Protein Xenograft Model Antitumor Assays Extracellular Matrix Gene Expression Regulation Neoplastic Insulin-Like Growth Factor Binding Proteins Cancer research Tumor Suppressor Protein p53 Proto-Oncogene Proteins c-akt |
| Zdroj: | Oncogene. 33:3024-3032 |
| ISSN: | 1476-5594 0950-9232 |
| Popis: | SMARCB1 (Snf5/Ini1/Baf47) is a potent tumor suppressor, the loss of which serves as the diagnostic feature in malignant rhabdoid tumors (MRT) and atypical teratoid/rhabdoid tumors (AT/RT), two highly aggressive forms of pediatric neoplasms. SMARCB1 is a core subunit of Swi/Snf chromatin remodeling complexes, and loss of SMARCB1 or other subunits of these complexes has been observed in a variety of tumor types. Here, we restore Smarcb1 expression in cells derived from Smarcb1-deficient tumors, which developed in Smarcb1 heterozygous p53(-/-) mice. We find that while re-introduction of Smarcb1 does not induce growth arrest, it restores sensitivity to programmed cell death and completely abolishes the ability of the tumor cells to grow as xenografts. We describe persistent activation of AKT signaling in Smarcb1-deficient cells, which stems from PI3K (phosphatidylinositol 3'-kinase)-mediated signaling and which contributes to the survival and proliferation of the tumor cells. We further demonstrate that inhibition of AKT is effective in preventing proliferation of Smarcb1-deficient cells in vitro and inhibits the development of xenografted tumors in vivo. Profiling Smarcb1-dependent gene expression, we find genes that require Smarcb1 and Swi/Snf for their expression to be enriched for extracellular matrix and cell adhesion functions. We find that Smarcb1 is required for transcriptional activation of Igfbp7, a member of the insulin-like growth factor-binding proteins family and a tumor suppressor in itself, and show that re-introduction of Igfbp7 alone can hinder tumor development. Our results define a novel mechanism for Smarcb1-mediated tumorigenesis and highlight potential therapeutic targets. |
| Databáze: | OpenAIRE |
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