51. The Cks1/Cks2 axis fine-tunes Mll1 expression and is crucial for MLL-rearranged leukaemia cell viability
- Author
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William, Grey, Adam, Ivey, Thomas A, Milne, Torsten, Haferlach, David, Grimwade, Frank, Uhlmann, Edwige, Voisset, and Veronica, Yu
- Subjects
Gene Rearrangement ,CKS2 ,Leukemia ,Oncogene Proteins, Fusion ,Cell Survival ,Gene Expression Regulation, Leukemic ,Cell Cycle Proteins ,Histone-Lysine N-Methyltransferase ,Embryo, Mammalian ,MLL-fusion proteins ,Article ,Mice ,Wnt ,CKS1B ,SKP2/CKS1 inhibitor ,CDC2-CDC28 Kinases ,Animals ,Humans ,MLL1 ,Carrier Proteins ,CDC28 Protein Kinase, S cerevisiae ,Cells, Cultured ,Myeloid-Lymphoid Leukemia Protein ,Signal Transduction - Abstract
The Cdc28 protein kinase subunits, Cks1 and Cks2, play dual roles in Cdk-substrate specificity and Cdk-independent protein degradation, in concert with the E3 ubiquitin ligase complexes SCFSkp2 and APCCdc20. Notable targets controlled by Cks include p27 and Cyclin A. Here, we demonstrate that Cks1 and Cks2 proteins interact with both the MllN and MllC subunits of Mll1 (Mixed-lineage leukaemia 1), and together, the Cks proteins define Mll1 levels throughout the cell cycle. Overexpression of CKS1B and CKS2 is observed in multiple human cancers, including various MLL-rearranged (MLLr) AML subtypes. To explore the importance of MLL-Fusion Protein regulation by CKS1/2, we used small molecule inhibitors (MLN4924 and C1) to modulate their protein degradation functions. These inhibitors specifically reduced the proliferation of MLLr cell lines compared to primary controls. Altogether, this study uncovers a novel regulatory pathway for MLL1, which may open a new therapeutic approach to MLLr leukaemia., Highlights • Mll1 is controlled by the Cks1/Cks2 axis. • Opposing effects: Cks1 promotes Mll1 degradation, while Cks2 stabilises Mll1. • Cks1/Cks2 impact on Wnt signalling through Mll1. • CKS1 and CKS2 are overexpressed in MLL-rearranged AML. • Pharmacological inhibition of SCFSKP2-CKS1 is cytotoxic for MLL-rearranged AML.
- Published
- 2017