The antimicrobial peptide cecropin A induces caspase-independent cell death in human promyelocytic leukemia cells.
Most antimicrobial peptides have been shown to have antitumoral activity. Cecropin A, a linear 37-residue antimicrobial polypeptide produced by the cecropia moth, has exhibited cytotoxicity in various human cancer cell lines and inhibitory effects on tumor growth. In this study, we investigated the apoptosis induced by cecropin A in the promyelocytic cell line HL-60. Treatment of cells with cecropin A was characterized by loss of viability in a dose-dependent manner, lactate dehydrogenase (LDH) leakage, and modest attenuation of lysosomal integrity measured by neutral red assay. An increase of reactive oxygen species (ROS) generation, DNA fragmentation, and phosphatidylserine externalization were quantified following cecropin A exposure at a concentration of 30 microM, whereas cecropin A-induced apoptosis was independent of caspase family members, because the activity of caspase-8 and -9 were irrelevant. Nevertheless, caspase-3 activity showed a significant increase at concentrations of 20-40 microM, but a considerable reduction at 50 microM. Flow cytometry analysis revealed a dissipation of the mitochondrial transmembrane potential (Deltapsi(m)), and the accumulation of cells at sub-G1 phase measured by FACS analysis of propidium iodide (PI) stained nuclei suggested induction of apoptosis. Morphological changes measured by Hoechst 33342 or acridine orange/ethidium bromide staining showed nuclear condensation, corroborating the apoptotic action of cecropin A. Overall, these data indicate that cecropin A is able to induce apoptosis in HL-60 cells through a signaling mechanism mediated by ROS, but independently of caspase activation.
Cerón
José María
JM
Division of Microbiology, Department of Health Sciences, Faculty of Experimental Sciences, University of Jaén, E-23071 Jaén, Spain.
Contreras-Moreno
Judit
J
Puertollano
Elena
E
de Cienfuegos
Gerardo Álvarez
GÁ
Puertollano
María A
MA
de Pablo
Manuel A
MA
D023181:Antimicrobial Cationic Peptides / Q000627:therapeutic use*; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D017209:Apoptosis / Q000187:drug effects*; D020169:Caspases / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002467:Cell Nucleus / Q000187:drug effects / Q000473:pathology; D002470:Cell Survival / Q000187:drug effects; D053938:DNA Fragmentation / Q000187:drug effects; D018922:HL-60 Cells; D006801:Humans; D019476:Insect Proteins / Q000627:therapeutic use; D015473:Leukemia, Promyelocytic, Acute / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D008247:Lysosomes / Q000187:drug effects; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D009994:Osmolar Concentration; D010718:Phosphatidylserines / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D016192:Resting Phase, Cell Cycle / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects
D023181:Antimicrobial Cationic Peptides; D000970:Antineoplastic Agents; D019476:Insect Proteins; D010718:Phosphatidylserines; D017382:Reactive Oxygen Species; C031161:cecropin A; D020169:Caspases