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

Treatment of chronic myeloid leukemia (CML) with imatinib mesylate and other second- and/or third-generation c-Abl-specific tyrosine kinase inhibitors (TKIs) has substantially extended patient survival. However, TKIs primarily target differentiated cells and do not eliminate leukemic stem cells (LSCs). Therefore, targeting minimal residual disease to prevent acquired resistance and/or disease relapse requires identification of new LSC-selective target(s) that can be exploited therapeutically. Considering that malignant transformation involves cellular metabolic changes, which may in turn render the transformed cells susceptible to specific assaults in a selective manner, we searched for such vulnerabilities in CML LSCs. We performed metabolic analyses on both stem cell-enriched (CD34

Topics: Animals; Anti-Bacterial Agents; Blotting, Western; Cell Survival; Chromatography, Liquid; Drug Resistance, Neoplasm; Drug Therapy, Combination; Female; Humans; Hypoglycemic Agents; Imatinib Mesylate; In Vitro Techniques; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; Mass Spectrometry; Metabolomics; Mice; Mice, Inbred NOD; Minocycline; Mitochondria; Neoplastic Stem Cells; Oxidative Phosphorylation; Phenformin; Protein Kinase Inhibitors; Reverse Transcriptase Polymerase Chain Reaction; Tigecycline; Tumor Cells, Cultured; Tumor Stem Cell Assay; Up-Regulation; Xenograft Model Antitumor Assays

Drug resistance and disease progression are still the major obstacles in the treatment of chronic myeloid leukemia (CML). Increasing researches have demonstrated that autophagy becomes activated when cancer cells are subjected to chemotherapy, which is involved in the development of drug resistance. Therefore, combining chemotherapy with inhibition of autophagy serves as a new strategy in cancer treatment. Tigecycline is an antibiotic that has received attention as an anti-cancer agent due to its inhibitory effect on mitochondrial translation. However, whether combination of tigecycline with inhibition of autophagy could overcome drug resistance in CML remains unclear.. We analyzed the biological and metabolic effect of tigecycline on CML primary cells and cell lines to investigate whether tigecycline could regulate autophagy in CML cells and whether coupling autophagy inhibition with treatment using tigecycline could affect the viabilities of drug-sensitive and drug-resistant CML cells.. Tigecycline inhibited the viabilities of CML primary cells and cell lines, including those that were drug-resistant. This occurred via the inhibition of mitochondrial biogenesis and the perturbation of cell metabolism, which resulted in apoptosis. Moreover, tigecycline induced autophagy by downregulating the PI3K-AKT-mTOR pathway. Additionally, combining tigecycline use with autophagy inhibition further promoted the anti-leukemic activity of tigecycline. We also observed that the anti-leukemic effect of tigecycline is selective. This is because the drug targeted leukemic cells but not normal cells, which is because of the differences in the mitochondrial biogenesis and metabolic characterization between the two cell types.. Combining tigecycline use with autophagy inhibition is a promising approach for overcoming drug resistance in CML treatment.

Topics: Autophagy; Autophagy-Related Proteins; Cell Line, Tumor; Cell Survival; Drug Resistance, Neoplasm; Drug Synergism; Gene Expression Regulation, Leukemic; Gene Silencing; Humans; K562 Cells; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; Minocycline; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; Signal Transduction; Tigecycline; TOR Serine-Threonine Kinases

We investigated mechanisms of cytotoxicity induced by doxycycline (doxy) and minocycline (mino) in the chronic myeloid leukemia K562 cell line. Doxy and mino induced cell death in exposure-dependent manner. While annexin V/propidium iodide staining was consistent with apoptosis, the morphological changes in Giemsa staining were more equivocal. A pancaspase inhibitor Z-VAD-FMK partially reverted cell death morphology, but concurrently completely prevented PARP cleavage. Mitochondrial involvement was detected as dissipation of mitochondrial membrane potential and cytochrome C release. DNA double strand breaks detected with γH2AX antibody and caspase-2 activation were found early after the treatment start, but caspase-3 activation was a late event. Decrement of Bcl-xL protein levels and electrophoretic shift of Bcl-xL molecule were induced by both drugs. Phosphorylation of Bcl-xL at serine 62 was ruled out. Similarly, Bcr/Abl tyrosine kinase levels were decreased. Lysosomal inhibitor chloroquine restored Bcl-xL and Bcr/Abl protein levels and inhibited caspase-3 activation. Thus, the cytotoxicity of doxy and mino in K562 cells is mediated by DNA damage, Bcl-xL deamidation and lysosomal degradation with activation of mitochondrial pathway of apoptosis.

Topics: Anti-Bacterial Agents; Antineoplastic Agents; Apoptosis; bcl-X Protein; Caspase 3; DNA Damage; Doxycycline; Enzyme Activation; Fusion Proteins, bcr-abl; Humans; K562 Cells; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; Minocycline; Proteolysis