Study on the Molecular Mechanism and Therapeutic Potential of MK-2206 in AML
Date Issued
2012
Date
2012
Author(s)
Lai, Yen-Ling
Abstract
Phosphoinositide 3-kinase (PI3K)/Akt signaling pathway can regulate cell proliferation, apoptosis and play a critical role in maintaining normal cell function. It has been demonstrated that abnormal PI3K/Akt activation occurred in various cancers, including human acute myeloid leukemia (AML). As a result, many PI3K/Akt inhibitors were created to target this uncontrolled pathway, including MK-2206, an allosteric Akt inhibitor. We used MTS assay (cell proliferation assay) to evaluate the potency of MK-2206 on AML. MK-2206 was more cytotoxic to AML cell at low dose (IC50 < 3 μM) comparing to normal peripheral blood mononuclear cells (IC50 > 18.8 μM), thus demonstrated its biosercurity. Next, treatment of MK-2206 on AML cells resulted in cell cycle G1 arrest and induced apoptosis by using flow cytometry analysis. Further investigation on apoptosis-related molecules demonstrated myeloid cell leukemia 1 (Mcl-1) reduction when AML cells treated with MK-2206. Mcl-1 is an anti-apoptotic molecule. By using proteasome inhibitor MG-132 or glycogen synthase kinase 3 (GSK3) inhibitor lithium chloride, we found that Mcl-1 reduction by MK-2206 on AML cells resulted from proteasome degradation mediated by GSK3. To detect the efficacy of MK-2206 with plasma-reachable dose, 200 nM MK-2206 was used to evaluate the sensitivity of cytarabine. We found that combination of 200 nM and 75 nM cytarabine revealed similar effect of 150 nM cytarabine only. Cytarabine is a chemotherapeutic drug commonly used in AML treatment. However, no response or acquired resistance to cytarabine are frequently shown in AML patients. Thus, we established a cytarabine-resistant MV-4-11 (MV-4-11-R) cell line. The N/C ratio of MV-4-11-R was large and the chromatin of MV-4-11-R was less condensed compared with its parental cell (MV-4-11-P). There were more much more expression of CD56 and less expression of HLA-DR in MV-4-11-R compared with MV-4-11-P by using flow cytometry analysis. MV-4-11-R showed slower proliferation kinetics than MV-4-11-P. There was much more Akt and ERK phosphorylation in MV-4-11-R than MV-4-11-P by using Phospho-kinase Array analysis and western blot analysis. Subsequently, combination of Akt inhibitor MK-2206 and MEK inhibitor CI-1040 demonstrated significantly synergistic effect (CI < 1) in MV-4-11-R and its parental cell. As a result, we demonstrated that combination of MK-2206 and CI-1040 could inhibit proliferation of AML cells more effectively both in vitro and in vivo, representing a novel strategy to treat AML patients.
Subjects
Acute myeloid leukemia
Cytarabine resistance
SDGs
Type
thesis
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