Identifying novel drug targets to overcome resistance to tyrosine kinase inhibitors (TKIs) and eradicating leukemia stem/progenitor cells are required for the treatment of chronic myelogenous leukemia (CML). Here, we show that ubiquitin-specific peptidase 47 (USP47) is a potential target to overcome TKI resistance. Functional analysis shows that USP47 knockdown represses proliferation of CML cells sensitive or resistant to imatinib in vitro and in vivo. The knockout of Usp47 significantly inhibits BCR-ABL and BCR-ABLT315I-induced CML in mice with the reduction of Lin-Sca1+c-Kit+ CML stem/progenitor cells. Mechanistic studies show that stabilizing Y-box binding protein 1 contributes to USP47-mediated DNA damage repair in CML cells. Inhibiting USP47 by P22077 exerts cytotoxicity to CML cells with or without TKI resistance in vitro and in vivo. Moreover, P22077 eliminates leukemia stem/progenitor cells in CML mice. Together, targeting USP47 is a promising strategy to overcome TKI resistance and eradicate leukemia stem/progenitor cells in CML.
Drug Resistance, Neoplasm , Leukemia, Myelogenous, Chronic, BCR-ABL Positive/pathology , Neoplastic Stem Cells/metabolism , Neoplastic Stem Cells/pathology , Protein Kinase Inhibitors/pharmacology , Ubiquitin Thiolesterase/metabolism , Ubiquitin-Specific Proteases/metabolism , Animals , Cell Proliferation/drug effects , DNA Damage , DNA Repair/drug effects , Drug Resistance, Neoplasm/drug effects , Extracellular Signal-Regulated MAP Kinases/metabolism , Fusion Proteins, bcr-abl , Gene Expression Regulation, Leukemic/drug effects , Humans , K562 Cells , Leukemia, Myelogenous, Chronic, BCR-ABL Positive/genetics , Mice, Knockout , Proteasome Endopeptidase Complex/metabolism , Protein Binding/drug effects , Protein Stability/drug effects , Proteolysis/drug effects , RNA, Messenger/genetics , RNA, Messenger/metabolism , STAT5 Transcription Factor/metabolism , Signal Transduction/drug effects , Thiophenes/pharmacology , Xenograft Model Antitumor Assays , Y-Box-Binding Protein 1/metabolism , ras Proteins/metabolism
The spindle assembly checkpoint prevents chromosome mis-segregation during mitosis by delaying sister chromatid separation. Several F-box protein members play critical roles in maintaining genome stability and regulating cell cycle progress via ubiquitin-mediated protein degradation. Here, we showed that Fbxo6 critically regulated spindle checkpoint and chromosome segregation. Fbxo6 was phosphorylated during mitosis. Overexpression of Fbxo6 lead to faster exit from nocodazole-induced mitosis arrest through premature sister chromatid separation. Moreover, we found substantially more binuclear and multilobed nuclei cells accompanied with impaired cell viability in Fbxo6-overexpressed HeLa cells. Mechanistically, Fbxo6 interacted with spindle checkpoint proteins including Mad2 and BubR1 leading to the premature exit from mitosis. Overall, we revealed a novel role of Fbxo6 in regulating spindle checkpoint, which may shed light on the regulation of genome instability of cancer cells.
Mad2 Proteins/metabolism , Protein Serine-Threonine Kinases/metabolism , SKP Cullin F-Box Protein Ligases/metabolism , Chromatids/metabolism , Genomic Instability , HeLa Cells , Humans , M Phase Cell Cycle Checkpoints/drug effects , Mitosis/drug effects , Nocodazole/pharmacology , Phosphorylation/drug effects , SKP Cullin F-Box Protein Ligases/genetics , Spindle Apparatus/metabolism
