Duocarmycin SA reduces proliferation and induces apoptosis in Acute Myeloid Leukemia cells in vitro

Abstract Acute myeloid leukemia (AML) is a blood cancer that is characterized by the clonal expansion of immature myeloid blasts. Duocarmycin SA (DSA) is an antitumor antibiotic that induces DNA alkylation and has demonstrated cytotoxic activity against several cancers, but not AML. Preliminary data from our lab demonstrated that DSA induced cytotoxic effects on AML cells in vitro. The objective of this study was to investigate the mechanism by which DSA exerts its cytotoxic effects on AML cells in vitro. We hypothesized that DSA will induce cell cycle arrest and contribute to cellular apoptosis. The human AML cell line (Molm-14) was used for all studies and the phenotype of the cells was confirmed by flow cytometry. To test our hypothesis, we performed dose response (MTT), proliferation (CFU and EdU) and apoptosis (Hoffman Modulation and Annexin V/7-AAD) assays. Our results showed that the AML cells were CD45+, CD33+, CD13+, CD14+ and CD4+ and the IC50 of DSA was ~11 pM. DSA induced cell cycle arrest at the G2/M phase, significantly decreased the production of colonies and significantly reduced the proliferation of AML cells in a dose-dependent manner (63.5%, 37.6%, 14.3% and 2.9% of EdU+ cells following treatment with 0, 20, 100 and 500 pM of DSA respectively for 96 hours). Finally, DSA also increased apoptosis of AML cells in a dose-dependent manner (4.5%, 9.4%, 56.7%, and 92.0% at 0, 20, 100 and 500 pM DSA respectively following treatment with DSA for 72 hours). In summary, picomolar concentrations of DSA induces cell cycle arrest, reduces proliferation and colony formation, and induces apoptosis as a mechanism of cell death in AML cells. Thus, highlighting DSA as a potential therapeutic candidate for further evaluation on AML cells. This work was supported by funding from the School of Pharmacy at Loma Linda University.