Abstract 5113: Synergistic effects of Deferasirox and Imatinib in chronic myeloid leukemia cells

Abstract

Abstract Chronic myelogenous leukemia (CML) is diagnosed by abnormal myeloid lineage cell proliferation and the presence of the Bcr-Abl fusion gene encoding abnormal tyrosine kinase. Imatinib mesylate (IM) is the first developed Bcr/Abl tyrosine-kinase inhibitor for the treatment of CML. Despite of high response rates, significant numbers of CML patients develop the resistance against these kinase inhibitors. Deferasirox (DFO) is an oral iron chelating agent that has been used to treat acute iron detoxification and chronically iron overloaded. Recent reports have been shown that iron chelators induce anti-proliferative effect in multiple leukemia cells. However, their roles and underlying mechanism in CML cell lines are not yet fully understood. In this study, we evaluated the combination effects of Deferasirox and Imatinib in CML cell line, and investigated their apoptosis -inducing effects as the potential mechanism in this process. Two CML cell lines (K562, KU812) were treated with various concentrations of Deferasirox, Imatinib and combination of two drugs. The viability and the level of apoptosis of the treated cells will be measured with MTT assay, FACS analysis and western blot. The results showed that both of them induce the growth inhibitory effects in dose and Time dependent fashion in both CML cell lines. Cell cycle analysis by FACS indicated that cell lines treated with combination therapy showed an increase in the proportion of cells in sub-G1 phase, compared to single treatment cell lines. Exposure of CML cells to IM/DFO also resulted in the increase in the percentage of annexin V-positive and PI-negative cells. The results by multiple in vitro experimental model, showed that IM/DFO induce CML cells to undergo apoptosis with the activation of caspase9 and 3, the cleavage of PARP and reduced significantly in parallel with BCR/ABL phosphorylation compared with treatment with IM or DFO alone. Importantly, inhibition of NF-kB activity demonstrated that IM/DFO-induced apoptotic pathway was regulated by the NF-kB signaling cascade. To determine the effect of IM/DFO on NF-κB transcriptional activity, a plasmid containing the luciferase reporter regulated by NF-κB cis-acting elements was used. The results showed that IM/DFO decreased NF-κB transcriptional activity in K562 and KU812 cells, respectively, compared to single treated cells. IM/DFO regulated the nuclear activation of NF-κB. In conclusion, this finding indicates that combination of Imatinib and Deferasirox, promotes apoptosis of CML cells by sequential regulation of the BCR/ABL expression followed by the inhibition of NF-kB signaling pathway. Citation Format: Dae Sik Kim, Myoung Hee Kang, Yoo Jin Na, Jung Lim Kim, Bo Ram Kim, Kyong Hwa Park, Sang Cheul Oh, Jae Hong Seo, Chul Won Choi, Jun Suk Kim. Synergistic effects of Deferasirox and Imatinib in chronic myeloid leukemia cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5113. doi:10.1158/1538-7445.AM2014-5113