novobiocin and Leukemia--Myelogenous--Chronic--BCR-ABL-Positive

To investigate the cytotoxicity of FM-Nov17 against chronic myeloid leukemia (CML) cells, we explored its underlying mechanisms mediating the induction of DNA damage and apoptotic cell death by reactive oxygen species (ROS).. MTT assays were used to measure the proliferation-inhibition ratio of K562 and K562/G01 cells. Flow cytometry (FCM) was used to test the level of extracellular ROS, DNA damage, cell cycle progression and apoptosis. Western blotting was used to verify the amount of protein.. FM-Nov17 significantly inhibited the proliferation of K562 cells, with an IC50 of 58.28±0.304μM, and K562/G01 cells, with an IC50 of 62.36±0.136μM. FM-Nov17 significantly stimulated the generation of intracellular ROS, followed by the induction of DNA damage and the activation of the ATM-p53-r-H2AX pathway and checkpoint-related signals Chk1/Chk2, which led to increased numbers of cells in the S and G2/M phases of the cell cycle. Furthermore, FM-Nov17 induced apoptotic cell death by decreasing mitochondrial membrane potential and activating caspase-3 and PARP. The above effects were all prevented by the ROS scavenger N-acetylcysteine.. FM-Nov17-induces DNA damage and mitochondria-dependent cellular apoptosis in CML cells. The process is mediated by the generation of ROS.

Topics: Acetylcysteine; Apoptosis; Caspase 3; Cell Cycle; Cell Line, Tumor; Cell Proliferation; DNA Damage; Humans; K562 Cells; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; Membrane Potential, Mitochondrial; Mitochondria; Novobiocin; Reactive Oxygen Species

Treatment of human K-562-J leukemia cells for 1 h with the topoisomerase II-reactive drugs VP-16, VM-26, or mAMSA resulted in a dose-dependent inhibition of proliferation and in an increase in the percentage of cells staining positive for hemoglobin, a marker of erythroid differentiation. Staining for hemoglobin of up to about 60% of the cells was observed at 20 microM VP-16, 1 microM VM-26, and 8 microM mAMSA. Such treatment also caused a G2/M arrest in the cell cycle. Incubation of the cells with radiolabeled VP-16 indicated that the induced erythroid differentiation was not due to continuous cell exposure to a residual amount of the drug. VP-16-induced erythroid differentiation was also not affected by DNA, RNA, or protein synthesis inhibitors. Differentiation induction and the G2/M arrest evoked by VP-16, VM-26, and mAMSA were, however, reduced in the presence of novobiocin. Our results indicate that topo-reactive drugs that cause G2/M arrest in the K-562-J cell cycle can induce in these cells erythroid differentiation after a short and irreversible interaction with their target molecule(s).

Topics: Amsacrine; Aphidicolin; Cell Cycle; Cell Differentiation; Cycloheximide; Deoxyadenosines; Dose-Response Relationship, Drug; Etoposide; G2 Phase; Hemoglobins; Humans; Kinetics; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; Melanins; Mitosis; Novobiocin; Teniposide; Topoisomerase II Inhibitors; Tumor Cells, Cultured