Cathepsin D promotes acute myeloid leukemia progression through stabilization of the anti-apoptotic proteins

Cathepsin D (CTSD) is a lysosomal aspartic protease that plays vital roles in regulating the properties of solid tumors, including proliferation, apoptosis, migration, metastasis, and angiogenesis. However, the function of CTSD in haematological malignancies remains largely elusive. Here we show that CTSD is highly expressed in acute myeloid leukemia (AML) and that high CTSD expression is associated with unfavourable prognosis. Knockdown of CTSD in AML cells inhibits cell proliferation and anti-apoptotic activity. Mechanistically, CTSD decreased the expression of the E3 ubiquitin ligase TRIM21, which mediates the ubiquitination and degradation of anti-apoptotic proteins BCL2, BCL-XL, and MCL1. Inhibition of CTSD expression via genetics or the small-molecule inhibitor N-8 decreases the protein levels of BCL2, BCL-XL, and MCL1 through accelerating their degradation. N-8 shows significant efficacy in eradicating AML in both venetoclax-sensitive and -resistant models. Collectively, our study reveals the role of CTSD in leukemia progression and highlights targeting CTSD as a potential therapeutic strategy in AML.