[Study on the Mechanism of CDC20 Inducing Cytarabine Resistance in Acute Myeloid Leukemia Cells by Targeting...

To investigate the role and mechanism of CDC20 in cytarabine (Ara-C) chemosensitivity of acute myeloid leukemia (AML) cells.

AML cell lines (Kasumi-1 and THP-1) with stable CDC20 overexpression or knockdown (shRNA) were established using lentiviral vectors. Cell viability and inhibition rates under Ara-C treatment (0, 0.25, 0.5, 1 μmol/L, 24 h) were assessed by the CCK-8 assay. Apoptosis was analyzed by flow cytometry. Protein expression of cleaved caspase-3, Bcl-2, LC3B, LC3B-II/LC3B-I ratio, p-AKT, and AKT was determined by Western blot. ROS levels were also measured. Autophagic activity was evaluated by transmission electron microscopy (autophagosome counting). The LC3B degradation pathway was investigated using cycloheximide (CHX) and MG132.

Compared with controls, CDC20 overexpression significantly reduced Ara-C-induced cell growth inhibition and apoptosis (P < 0.05), indicating enhanced chemoresistance; whereas CDC20 knockdown increased apoptosis and sensitivity. CDC20 overexpression decreased LC3B protein levels and the LC3B-II/LC3B-I ratio, suppressing autophagy, while CDC20 knockdown showed the opposite effects. CHX and MG132 assays confirmed that CDC20 promoted LC3B degradation via the ubiquitin-proteasome pathway, independent of transcription. CDC20 overexpression also increased p-AKT levels and reduced ROS generation, while CDC20 knockdown had the opposite effect. Rapamycin reversed the apoptosis inhibition and drug resistance induced by CDC20 overexpression.

CDC20 promotes LC3B degradation via the ubiquitin-proteasome pathway to suppress autophagy, while concurrently activating AKT signaling and reducing ROS levels, thereby synergistically driving Ara-C resistance in AML cells.