ABSTRACT
The plasma jet has been proposed as a novel therapeutic method for cancer. Anticancer activity of plasma has been reported to involve mitochondrial dysfunction. However, what constituents generated by plasma is linked to this anticancer process and its mechanism of action remain unclear. Here, we report that the therapeutic effects of air plasma result from generation of reactive oxygen/nitrogen species (ROS/RNS) including H2O2, Ox, OH-, â¢O2, NOx, leading to depolarization of mitochondrial membrane potential and mitochondrial ROS accumulation. Simultaneously, ROS/RNS activate c-Jun NH2-terminal kinase (JNK) and p38 kinase. As a consequence, treatment with air plasma jets induces apoptotic death in human cervical cancer HeLa cells. Pretreatment of the cells with antioxidants, JNK and p38 inhibitors, or JNK and p38 siRNA abrogates the depolarization of mitochondrial membrane potential and impairs the air plasma-induced apoptotic cell death, suggesting that the ROS/RNS generated by plasma trigger signaling pathways involving JNK and p38 and promote mitochondrial perturbation, leading to apoptosis. Therefore, administration of air plasma may be a feasible strategy to eliminate cancer cells.
Subject(s)
Air , Atmospheric Pressure , Neoplasms/metabolism , Plasma Gases/chemistry , Reactive Nitrogen Species/metabolism , Reactive Oxygen Species/metabolism , Antioxidants/pharmacology , Apoptosis/drug effects , Enzyme Activation/drug effects , Extracellular Space/metabolism , HeLa Cells , Humans , Intracellular Space/metabolism , JNK Mitogen-Activated Protein Kinases/metabolism , MAP Kinase Signaling System/drug effects , Membrane Potential, Mitochondrial/drug effects , Mitochondria/drug effects , Mitochondria/metabolism , Neoplasms/pathology , Phosphorylation/drug effects , Spectrum Analysis , p38 Mitogen-Activated Protein Kinases/metabolismABSTRACT
53BP1 (p53-binding protein 1) is a conserved nuclear protein that is phosphorylated in response to DNA damage and rapidly recruited to the site of DNA double strand breaks, demonstrating its role in the early events to DNA damage and repair of damaged DNA. In this study, we used the yeast two-hybrid system to identify proteins that interact with 53BP1. Identification and characterization of 53BP1 protein interactions may help to further elucidate the function and regulation of 53BP1. We identified protein phosphatase 5 (PP5), a serine/threonine phosphatase that has been implicated in multiple cellular function, as a 53BP1-binding protein. This interaction further confirmed that 53BP1 interacts with PP5 in PP5-overexpressing U2OS cells, after radiomimetic agent neocarzinostatin (NCS) treatment. 53BP1 dephosphorylation at Ser-25 and Ser-1778 was accelerated in PP5-overexpressing U2OS cells following NCS treatment, and its dephosphorylation was correlated with reduced phospho-53BP1 foci formation. In contrast, the overexpression of PP5 had no effect on NCS-activated BRCA1-Ser-1524 phosphorylation. Additionally, PP5 down-regulation inhibited the dephosphorylation of 53BP1 on Ser-1778 and the disappearance of phospho-53BP1 foci following NCS treatment. Moreover, non-homologous end-joining activity was reduced in PP5-overexpressing U2OS cells. These findings indicate that PP5 plays an important role in the regulation of 53BP1 phosphorylation and activity in vivo.
Subject(s)
Intracellular Signaling Peptides and Proteins/metabolism , Nuclear Proteins/metabolism , Phosphoprotein Phosphatases/metabolism , Cell Line , Cell Line, Tumor , DNA/metabolism , DNA Damage , DNA Repair , Down-Regulation , Humans , Microscopy, Fluorescence/methods , Nucleic Acid Synthesis Inhibitors/pharmacology , Phosphorylation , Protein Binding , Time Factors , Tumor Suppressor p53-Binding Protein 1 , Zinostatin/pharmacologyABSTRACT
An analytical CE method was developed for the enantiomeric purity determination of fluvastatin enantiomers. Fluvastatin enantiomers were separated on an uncoated fused silica with 100 mM-borate solution containing 30 mg/mL of (2-hydroxypropyl)-beta-cyclodextrin (HP-beta-CD) as running buffer and fenoprofen as an internal standard. The linearity was observed within a 400-700 microg/mL concentration range (r(2)>or=0.995) for both fluvastatin enantiomers. The repeatability expressed as coefficient of variation (CV) of the method were 0.96 and 0.92% for (+)-3R, 5S and (-)-3S, 5R-fluvastatin, respectively. The limit of detection and quantification for both fluvastatin enantiomers were 1.5 microg/mL and 2.5 microg/mL, respectively.
