Brusatol Triggers Cell Cycle Arrest and Apoptosis, Disrupts Sterol Biosynthesis, and Enhances the Anti-Leukemic Activity of Venetoclax in AML Cells.

Acute myeloid leukemia (AML) is an aggressive hematologic malignancy with poor prognosis. Although chemotherapy and targeted therapies have advanced significantly, relapse and chemoresistance continue to be the major clinical challenges, which emphasizes the need for novel treatments. Brusatol, a natural quassinoid compound, has been reported to exert anti-tumor effects in various solid tumors; however, its anti-leukemic activity and potential mechanism in AML remain poorly characterized. THP-1 and KG-1a cells were treated with brusatol alone or combined with venetoclax. Proliferation was evaluated by CCK-8, cell counting and morphological observation. Apoptosis was detected by flow cytometry, Western blot, morphological changes and TUNEL staining. RNA-seq with GO, KEGG, and GSEA was used to identify key pathways. Cell cycle was analyzed by flow cytometry. DNA synthesis was detected by EdU assay. mRNA expression was measured by qPCR. Protein levels were determined by Western blot. Brusatol significantly suppressed the proliferation of AML cells. Moreover, brusatol notably increased the apoptotic rate, upregulated the expression of cleaved‑PARP and Bax, downregulated MCL1, and induced typical apoptotic morphological changes. Transcriptomic analysis demonstrated that brusatol primarily modulated pathways related to the cell cycle and steroid biosynthesis. Brusatol downregulated the expression of MCM2, PCNA, and CDK2, thereby inducing cell cycle arrest and inhibiting DNA replication. Brusatol also significantly reduced the expression of key genes involved in steroid biosynthesis, including DHCR7, SQLE, EBP, and FDFT1. Furthermore, co-treatment with brusatol and venetoclax strengthens cell cycle arrest, proliferation inhibition and apoptosis induction in AML cells compared with single drug treatment. Brusatol inhibits AML cell proliferation, induces apoptosis, triggers cell‑cycle dysregulation, and downregulates sterol‑biosynthesis‑related gene expression. Brusatol also enhances the anti-leukemic activity of venetoclax. This study preliminarily elucidates the underlying mechanisms and provides experimental evidence supporting the potential therapeutic value of brusatol for acute myeloid leukemia.