Targeting USP14/UCHL5: A Breakthrough Approach to Overcoming Treatment-Resistant FLT3-ITD-Positive AML

Area of Science:

• Hematology
• Molecular Biology
• Oncology

Background:

• FMS-like tyrosine kinase 3 (FLT3) internal tandem duplication (ITD) mutations are linked to poor prognosis and resistance in acute myeloid leukemia (AML).
• Targeting deubiquitinating enzymes presents a potential therapeutic avenue for difficult-to-treat leukemias.

Purpose of the Study:

• To investigate the efficacy of inhibiting ubiquitin-specific peptidase 14 (USP14) and ubiquitin C-terminal hydrolase L5 (UCHL5) using b-AP15 or auranofin (AUR) in FLT3-ITD-positive AML.
• To elucidate the molecular mechanisms underlying the anti-leukemic effects of USP14/UCHL5 inhibition.

Main Methods:

• Treatment of MV4-11 cell line and patient-derived primary AML cells with b-AP15 or AUR.
• Assessment of apoptosis induction, FLT3 pathway signaling, deubiquitination, and translation initiation.
• Analysis of downstream targets including 4EBP1, MAP kinase pathways, NF-E2-related factor 2, BCL-XL, and MCL-1.

Main Results:

• Both b-AP15 and AUR induced apoptosis in FLT3-ITD-positive AML cells, an effect enhanced by USP14 knockdown.
• Treatments inhibited FLT3 deubiquitination and disrupted translation initiation via 4EBP1.
• FLT3 downregulation, activation of stress-related MAP kinase pathways, and increased NF-E2-related factor 2 were observed.
• Overexpression of BCL-XL and MCL-1 conferred resistance to b-AP15 and AUR-induced cell death.

Conclusions:

• Inhibition of USP14/UCHL5 with b-AP15 or AUR represents a promising therapeutic strategy for FLT3-ITD-positive AML.
• The observed effects involve complex regulatory mechanisms, including modulation of FLT3 deubiquitination and translation initiation.