| 1. |
- Hoellein, Alexander, et al.
(författare)
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Myc-induced SUMOylation is a therapeutic vulnerability for B-cell lymphoma.
- 2014
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Ingår i: Blood. - : American Society of Hematology. - 1528-0020 .- 0006-4971. ; 124:13, s. 2081-90
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Tidskriftsartikel (refereegranskat)abstract
- Myc oncogenic transcription factors (c-Myc, N-Myc, and L-Myc) coordinate the control of cell growth, division, and metabolism. In cancer, Myc overexpression is often associated with aggressive disease, which is in part due to the destruction of select targets by the ubiquitin-proteasome system (eg, SCF(Skp2)-directed destruction of the Cdk inhibitor p27(Kip1)). We reasoned that Myc would also regulate SUMOylation, a related means of posttranslational modification of proteins, and that this circuit would play essential roles in Myc-dependent tumorigenesis. Here, we report marked increases in the expression of genes that encode regulators and components of the SUMOylation machinery in mouse and human Myc-driven lymphomas, resulting in hyper-SUMOylation in these tumors. Further, inhibition of SUMOylation by genetic means disables Myc-induced proliferation, triggering G2/M cell-cycle arrest, polyploidy, and apoptosis. Using genetically defined cell models and conditional expression systems, this response was shown to be Myc specific. Finally, in vivo loss-of-function and pharmacologic studies demonstrated that inhibition of SUMOylation provokes rapid regression of Myc-driven lymphoma. Thus, targeting SUMOylation represents an attractive therapeutic option for lymphomas with MYC involvement.
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| 2. |
- Keller, Ulrich, et al.
(författare)
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Myc suppression of Nfkb2 accelerates lymphomagenesis
- 2010
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Ingår i: BMC Cancer. - : Springer Science and Business Media LLC. - 1471-2407. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Background: Deregulated c-Myc expression is a hallmark of several human cancers where it promotes proliferation and an aggressive tumour phenotype. Myc overexpression is associated with reduced activity of Rel/NF-kappa B, transcription factors that control the immune response, cell survival, and transformation, and that are frequently altered in cancer. The Rel/NF-kappa B family member NFKB2 is altered by chromosomal translocations or deletions in lymphoid malignancies and deletion of the C-terminal ankyrin domain of NF-kappa B2 augments lymphocyte proliferation. Methods: Precancerous E mu-Myc-transgenic B cells, E mu-Myc lymphomas and human Burkitt lymphoma samples were assessed for Nfkb2 expression. The contribution of Nfkb2 to Myc-driven apoptosis, proliferation, and lymphomagenesis was tested genetically in vivo. Results: Here we report that the Myc oncoprotein suppresses Nfkb2 expression in vitro in primary mouse fibroblasts and B cells, and in vivo in the E mu-Myc transgenic mouse model of human Burkitt lymphoma (BL). NFKB2 suppression by Myc was also confirmed in primary human BL. Promoter-reporter assays indicate that Myc-mediated suppression of Nfkb2 occurs at the level of transcription. The contribution of Nfkb2 to Myc-driven lymphomagenesis was tested in vivo, where Nfkb2 loss was shown to accelerate lymphoma development in E mu-Myc transgenic mice, by impairing Myc's apoptotic response. Conclusions: Nfkb2 is suppressed by c-Myc and harnesses Myc-driven lymphomagenesis. These data thus link Myc-driven lymphomagenesis to the non-canonical NF-kappa B pathway.
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