Contributions
Abstract: PB1668
Type: Publication Only
Background
Although two hypomethylating agents (HMAs), azacitidine and decitabine, are widely used for treatment of patients with myelodysplastic syndrome (MDS) and elderly acute myeloid leukemia (AML), most patients eventually experience resistance to the agents. Vosaroxin, an anti-cancer quinolone derivative, acts as a topoisomerase II inhibitor, and improved survival in a phase 3 study of vosaroxin in combination with cytarabine in relapsed/refractory AML.
Aims
We investigated anti-leukemic effects and mechanism of action of vosaroxin in HMA resistant cells.
Methods
We established three HMA resistant cell lines: MOLM/AZA-1 and MOLM/DEC-5 from MOLM-13 (AML/MDS cell line [Oncotarget 2017;8:11748]), and THP/DEC-2 from THP-1 (AML cell line). Cell viability was performed using Celltiter-glo luminescent cell viability assay (Promega, WI) and Operetta high-content imaging system (PerkinElmer, MA). The cell cycle distribution was determined by propidium iodide staining and flow cytometry. The proteins of apoptosis and cell cycle regulator were detected with immunoblot assay using specific primary antibodies.
Results
Vosaroxin caused dose-dependent inhibition of HMA resistant cells as well as MOLM-13 and THP-1 cells, and IC50 values of vosaroxin were significantly lower than those of azacitidine or decitabine. Vosaroxin induced increase of nuclear size in all cell lines except MOLM-13, in which DNA fragmentation was induced. DNA flow cytometric analysis exhibit G2/M arrest by vosaroxin. The immunoblotting showed increase of p53 and p21 expression in MOLM-13, MOLM/AZA-1 and MOLM/DEC-5 cells, increase of CDK2 and CDK4 expression, and decrease of Rb expression. Synergistic effects with combination of vosaroxin with decitabine were found in THP-1 and THP/DEC-2. Vosaroxin exerted in vitro anti-leukemic effects in 20 of 26 bone marrow samples from MDS patients.
Conclusion
Our preclinical studies demonstrated excellent anti-leukemic activities of vosaroxin in our HMA resistant models, and the effects seem to be attributed to cell cycle regulation of vosaroxin.
Session topic: 3. Acute myeloid leukemia - Biology & Translational Research
Keyword(s): AML, MDS, Resistance
Abstract: PB1668
Type: Publication Only
Background
Although two hypomethylating agents (HMAs), azacitidine and decitabine, are widely used for treatment of patients with myelodysplastic syndrome (MDS) and elderly acute myeloid leukemia (AML), most patients eventually experience resistance to the agents. Vosaroxin, an anti-cancer quinolone derivative, acts as a topoisomerase II inhibitor, and improved survival in a phase 3 study of vosaroxin in combination with cytarabine in relapsed/refractory AML.
Aims
We investigated anti-leukemic effects and mechanism of action of vosaroxin in HMA resistant cells.
Methods
We established three HMA resistant cell lines: MOLM/AZA-1 and MOLM/DEC-5 from MOLM-13 (AML/MDS cell line [Oncotarget 2017;8:11748]), and THP/DEC-2 from THP-1 (AML cell line). Cell viability was performed using Celltiter-glo luminescent cell viability assay (Promega, WI) and Operetta high-content imaging system (PerkinElmer, MA). The cell cycle distribution was determined by propidium iodide staining and flow cytometry. The proteins of apoptosis and cell cycle regulator were detected with immunoblot assay using specific primary antibodies.
Results
Vosaroxin caused dose-dependent inhibition of HMA resistant cells as well as MOLM-13 and THP-1 cells, and IC50 values of vosaroxin were significantly lower than those of azacitidine or decitabine. Vosaroxin induced increase of nuclear size in all cell lines except MOLM-13, in which DNA fragmentation was induced. DNA flow cytometric analysis exhibit G2/M arrest by vosaroxin. The immunoblotting showed increase of p53 and p21 expression in MOLM-13, MOLM/AZA-1 and MOLM/DEC-5 cells, increase of CDK2 and CDK4 expression, and decrease of Rb expression. Synergistic effects with combination of vosaroxin with decitabine were found in THP-1 and THP/DEC-2. Vosaroxin exerted in vitro anti-leukemic effects in 20 of 26 bone marrow samples from MDS patients.
Conclusion
Our preclinical studies demonstrated excellent anti-leukemic activities of vosaroxin in our HMA resistant models, and the effects seem to be attributed to cell cycle regulation of vosaroxin.
Session topic: 3. Acute myeloid leukemia - Biology & Translational Research
Keyword(s): AML, MDS, Resistance