title: PKC-δ/PKC-α activity balance regulates the lethal effects of cisplatin.
abstract: Cisplatin is commonly employed in therapy of mesothelioma but its efficacy is limited and the mechanisms by which induces its effects are not clearly understood. PKCs can regulate cisplatin sensitivity. PKCs effects on cellular sensitivity/resistance depend on the pattern of active PKC isozymes as well as on cellular context. The present study was undertaken to determine if specific PKC isoforms regulate cisplatin-induced apoptosis in the human mesothelioma ZL55 cells. Cells were treated with cisplatin at various concentrations and for different incubation periods. Cytotoxicity assays and Western blottings of various proteins involved in apoptosis and survival were then performed. Exposure of ZL55 cells to cisplatin at concentrations ranging from 1 to 200 μM resulted in a dose-dependent inhibition of cell survival and the activation of the mitochondrial apoptotic pathway. Cisplatin activated full-length PKC-δ and generated a PKC-δ fragment. PKC-δ inhibition (by PKC-δ-siRNA) decreased ZL55 cell apoptosis. Full-length PKC-δ translocated to the nucleus and activated caspase-3 expression, whereas PKC-δ fragment preferentially localized to mitochondria. Cisplatin also provoked the generation of reactive oxygen species (ROS) by NADPH oxidase. ROS increment was responsible for the PKC-α activation that provoked EGFR transactivation and consequential phosphorylation of ERK1/2. The inhibition of this pathway at various level (PKC-α, EGFR or ERK1/2) increased cisplatin-induced cytotoxicity. The results suggest that PKC-δ is an essential part of the apoptotic program in mesothelioma cells, whereas PKC-α mediates a pro-survival response to cisplatin.
authors: Cell Pathology Lab, Dipartimento di Scienze e Tecnologie Biologiche e Ambientali (Di.S.Te.B.A.), Salento University, Lecce, Italy.
authors: Antonella
authors: A
authors: Muscella
authors: Neuropathology Unit, Istituto di Neurologia sperimentale e Divisione di Neuroscienze, Istituto Scientifico IRCCS San Raffaele (sezione di Lecce), Milano, Italy.
authors: Carla
authors: C
authors: Vetrugno
authors: Cell Physiology Lab, Dipartimento di Scienze e Tecnologie Biologiche e Ambientali (Di.S.Te.B.A.), Salento University, Lecce, Italy.
authors: Giovanna
authors: G
authors: Antonaci
authors: Cell Physiology Lab, Dipartimento di Scienze e Tecnologie Biologiche e Ambientali (Di.S.Te.B.A.), Salento University, Lecce, Italy.
authors: Luca Giulio
authors: LG
authors: Cossa
authors: Cell Physiology Lab, Dipartimento di Scienze e Tecnologie Biologiche e Ambientali (Di.S.Te.B.A.), Salento University, Lecce, Italy. Electronic address: santo.marsigliante@unisalento.it.
authors: Santo
authors: S
authors: Marsigliante
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000494:pharmacology* / Q000627:therapeutic use; D004789:Enzyme Activation / Q000187:drug effects*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000235:genetics / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006801:Humans; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008654:Mesothelioma / Q000188:drug therapy; D051571:Protein Kinase C-alpha / Q000378:metabolism*; D051745:Protein Kinase C-delta / Q000378:metabolism*; D017382:Reactive Oxygen Species
chemical_list: D000970:Antineoplastic Agents; D017382:Reactive Oxygen Species; D051571:Protein Kinase C-alpha; D051745:Protein Kinase C-delta; D048049:Extracellular Signal-Regulated MAP Kinases; D002945:Cisplatin
keywords: Apoptosis; Cisplatin; EGFR; ERK; Mesothelioma; Mitochondria; PKC; ROS