[Establishment and Mechanistic Study of Venetoclax-Resistant Cell Lines in Acute Myeloid Leukemia]

To establish venetoclax-resistant acute myeloid leukemia (AML) cell lines, assess the sensitivity of venetoclax-resistant cell lines to the BCL-2 protein family, and investigate their resistance mechanisms.

CCK-8 method was used to screen AML cell lines (MV4-11, MOLM13, OCI-AML2) that were relatively sensitive to venetoclax. Low concentrations of venetoclax continuously induced drug-resistance development in the cell lines. Changes in cell viability and apoptosis rate before and after resistance development were measured using the CCK-8 method and flow cytometry. BH3 profiling assay was performed to anayze the transform of mitochondrion-dependent apoptosis pathway as well as the sensitivity of resistant cell lines to BCL-2 family proteins and small molecule inhibitors. Real-time fluorescence quantitative PCR (RT-qPCR) was utilized to examine changes in the expression levels of BCL-2 protein family members in both venetoclax-resistant cell lines and multidrug-resistant patients.

Venetoclax-resistant cell lines of MV4-11, MOLM13, and OCI-AML2 were successfully established, with IC₅₀ values exceeding 10-fold. Under the same concentration of venetoclax, the apoptosis rate of resistant cells decreased significantly (P < 0.05). BH3 profiling assay revealed that the drug-resistant cell lines showed increased sensitivity to many pro-apoptotic proteins (such as BIM,BID and NOXA). RT-qPCR showed significantly upregulated MCL1 and downregulated NOXA1 were detected in drug-resistant cell lines. Expression changes in MCL1 and NOXA1 in venetoclax-resistant patients were consistent with our established drug-resistant cell line results.

The venetoclax-resistant AML cell lines were successfully established through continuous induction with low concentrations of venetoclax. The venetoclax resistance resulted in alterations in the mitochondrial apoptosis pathway of the cells and an increased sensitivity of cells to pro-apoptotic proteins BIM, BID, and NOXA, which may be associated with the upregulation of MCL1 expression and downregulation of NOXA1 expression in the drug-resistant cells.