Deubiquitinase USP5 promotes acute myeloid leukemia through C2CD5 stabilization and PI3K/AKT/mTOR/HIF-1α-driven...

Acute myeloid leukemia (AML) remains a therapeutic challenge with poor prognosis, particularly in high-risk genetic subtypes. Ubiquitin-specific protease 5 (USP5) plays a crucial role in the progression of various malignancies. However, its function in AML remains largely unknown. This study aims to investigate the biological role of USP5 in AML and elucidate its underlying molecular mechanisms. We observed that USP5 expression was significantly elevated in AML patients compared to healthy controls, and high USP5 levels correlated with poor prognosis. Functional studies demonstrated that USP5 knockdown markedly inhibited AML cell proliferation, colony formation, and cell cycle progression while promoting apoptosis. In vivo experiments revealed that USP5 depletion significantly suppressed leukemia cell proliferation and prolonged survival in AML mouse model. Mechanistically, co-immunoprecipitation coupled with mass spectrometry analysis identified that USP5 interacted with a protein complex containing C2 domain protein 5 (C2CD5), FGF1 intracellular binding protein (FIBP), and cyclin-dependent kinase 5 (CDK5). Notably, USP5 stabilizes C2CD5 through deubiquitination, thereby activating the phosphoinositide 3-kinase (PI3K)/ (protein kinase B) AKT/ mechanistic target of rapamycin (mTOR) signaling pathway and enhancing glycolytic flux via the HIF-1α transcription factor to drive AML progression. Importantly, USP5 knockdown enhanced the chemosensitivity of AML cells, and its small-molecule inhibitor potently curbed AML cell growth and proliferation. Generally, our findings establish the USP5-C2CD5 as a novel therapeutic target for AML treatment.