The Deubiquitinating Enzyme USP14 Regulates Leukemic Chemotherapy Drugs-Induced Cell Apoptosis by Suppressing Ubiquitination of Aurora Kinase B.

BACKGROUND/AIMS: Aurora kinase B is a mitotic checkpoint kinase that plays a pivotal role in mitosis by ensuring correct chromosome segregation and normal progression through mitosis. Aurora B has been found to be amplified and overexpressed in several types of leukemia. The deubiquitinating enzyme USP14 is one of three proteasome-associated deubiquitinating enzymes and plays critical roles in diverse biological processes including cancer. However, whether USP14 has a role in leukemia cells remains elusive. METHODS: Leukemic U937, NB4 and Jurkat cells were treated with diverse apoptosis-inducing drugs. The interaction between USP14 and Aurora B were determined by Western blot. The effect of USP14 in the regulation of Aurora B was detected by cycloheximide (CHX) and deubiquitination assays. FACS assay was used to determine the apoptosis ratio of cells after treatments. RESULTS: We found that Aurora B was ubiquitinated and degraded during leukemic chemotherapy drugs-induced cell apoptosis. FBXW7 mediated Aurora B ubiquitination and degradation during chemotherapeutic drugs-induced apoptosis. USP14 associated with Aurora B and prevented Aurora B degradation. Functionally, overexpression of USP14 inhibits chemotherapeutic drugs-induced apoptosis in leukemia cells. On the contrary, administration of b-AP15, a specific inhibitor of USP14, significantly increased leukemia cells apoptosis in a dose-dependent manner. CONCLUSION: Thus, our data suggest that USP14 plays a novel critical role of in leukemia cells apoptosis through Aurora B stabilization and USP14 could be a potential therapeutic target for leukemia.

Identification of key regulatory pathways of myeloid differentiation using an mESC-based karyotypically normal cell model.

Understanding the process of myeloid differentiation offers important insights into both normal and abnormal developmental processes but is limited by the dearth of experimental models. Here we show that myeloid progenitors can be derived from embryonic stem cells, immortalized, and applied to the study of the mechanisms underlying myeloid differentiation. The embryonic stem cell-derived myeloid progenitors, when immortalized with estrogen-regulated Hoxb8 protein, demonstrate normal karyotyping, are genetically tractable, and can be differentiated into functional neutrophils. Using this model, we identified mammalian target of rapamycin complex 1 as a critical regulator of myeloid differentiation. Together, our studies led to a convenient, karyotypically normal, and genetically manipulatable cellular system, which can be used to shed new light on the mechanisms for myeloid differentiation.

LINC00665 promotes the progression of acute myeloid leukemia by regulating the miR-4458/DOCK1 pathway.

This study aimed to explore the role of LINC00665, miR-4458 and DOCK1 and their interactions in the development of acute myeloid leukemia (AML). The relative expression of LINC00665, miR-4458 and DOCK1 in AML samples was measured using qRT-PCR, and the protein level of DOCK1 in AML cell lines was examined using western blot. CCK8, BrdU, transwell, cell adhesion, and caspase-3 activity assays were carried out to evaluate the viability, proliferation, migration, adhesion, and apoptosis of AML cells, respectively. Luciferase reporter, RIP, and RNA pull-down assays were also performed to confirm the target relationship among LINC00665, miR-4458 and DOCK1. Findings revealed that LINC00665 and DOCK1 were aberrantly overexpressed in AML tissues and that the expression of miR-4458 was low in AML tissues. Silencing LINC00665 or DOCK1 presented significant restriction to the proliferation, migration and adhesion of AML cells. Apart from that, it was found that inhibiting miR-4458 could enhance the proliferation, migration and adhesion of AML cells but suppress the apoptosis of AML cells. Experimental results also indicated that LINC00665 exerted its positive function on AML cells by sponging miR-4458 and that miR-4458 influenced the progression of AML cells by targeting DOCK1 directly. Overall, this finding not only provided a novel molecular pathway for the diagnosis and treatment of AML but also showed that LINC00665 could enhance the progression of AML by regulating the miR-4458/DOCK1 pathway.