NAD(P)H oxidases were detected in suspension cultured cells of ginseng (Panax ginseng C. A. Meyer). The activities of these enzymes were induced by an elicitor (Cle) extracted from cell walls of Col-letotrichum lagera...NAD(P)H oxidases were detected in suspension cultured cells of ginseng (Panax ginseng C. A. Meyer). The activities of these enzymes were induced by an elicitor (Cle) extracted from cell walls of Col-letotrichum lagerarium. In addition, Cle induced an oxidative burst and enhanced the synthesis of saponin, activity of phenylalanine ammonialyase (PAL) , accumulation of chalcone synthase (CHS) and the transcription of a hydroxyproline-rich glycoprotein gene ( hrgp ) . Pre-treatments with DPI and quinacrine (two inhibitors of mammalian neutrophil plasma membrane NADPH oxidase) for 30 min prior to Cle addition blocked the NAD(P)H oxidase activity induced by Cle. These inhibitors also inhibited the release of H2C2, the synthesis of saponin, PAL activity and CHS accumulation. Our data revealed homology between plasma membrane NAD(P)H oxidases of mammalian neutrophil cells and ginseng suspension cells. They also indicated that deactivated NAD(P)H oxidases catalysed the release of H2O2 and that H2O2 was functioning as a second messenger stimulating PAL activity, saponin synthesis and hrgp transcription. Elevations of Ca2 + and protein phos-phorylation/dephosphorylation were required for this defense process. We propose that NAD(P)H oxidases mediate the processes of Cle-induced defense responses in ginseng suspensions, and postulate the existence of a signalling cascade including extracellular Cle stimulation, activation of plasma membrane NAD(P)H oxidases, release of H2O2, and the intracellular responses of metabolism and gene transcription in ginseng suspension cells.展开更多
Introduction:Oncogenic aaivation of the K-ras gene occurs in >90%of pancreatic ductal carcinoma and plays a critical role in the pathogenesis of this malignancy.Increase of reactive oxygen species(ROS) has also bee...Introduction:Oncogenic aaivation of the K-ras gene occurs in >90%of pancreatic ductal carcinoma and plays a critical role in the pathogenesis of this malignancy.Increase of reactive oxygen species(ROS) has also been observed in a wide spectrum of cancers.This study aimed to investigate the mechanistic association between K-ras-induced transformation and increased ROS stress and its therapeutic implications in pancreatic cancer.Methods:ROS level,NADPH oxidase(NOX) aaivity and expression,and cell invasion were examined in human pancreatic dua epithelial E6E7 cells transfeaed with K-ras^(G12V) compared with parental E6E7 cells.The cytotoxic effea and antitumor effect of capsaicin,a NOX inhibitor,were also tested in vitro and in vivo.Results:K-ras transfeaion caused activation of the membrane-associated redox enzyme NOX and elevated ROS generation through the phosphatidylinositol 3'-kinase(PI3K) pathway.Importantly,capsaicin preferentially inhibited the enzyme aaivity of NOX and induced severe ROS accumulation in K-ras-transformed cells compared with parental E6E7 cells.Furthermore,capsaicin effeaively inhibited cell proliferation,prevented invasiveness of /(-ras-transformed pancreatic cancer cells,and caused minimum toxicity to parental E6E7 cells.In vivo,capsaicin exhibited antitumor aaivity against pancreatic cancer and showed oxidative damage to the xenograft tumor cells.Conclusions:K-ras oncogenic signaling causes increased ROS stress through NOX,and abnormal ROS stress can selectively kill tumor cells by using NOX inhibitors.Our study provides a basis for developing a novel therapeutic strategy to effectively kill K-ras-transformed cells through a redox-mediated mechanism.展开更多
文摘NAD(P)H oxidases were detected in suspension cultured cells of ginseng (Panax ginseng C. A. Meyer). The activities of these enzymes were induced by an elicitor (Cle) extracted from cell walls of Col-letotrichum lagerarium. In addition, Cle induced an oxidative burst and enhanced the synthesis of saponin, activity of phenylalanine ammonialyase (PAL) , accumulation of chalcone synthase (CHS) and the transcription of a hydroxyproline-rich glycoprotein gene ( hrgp ) . Pre-treatments with DPI and quinacrine (two inhibitors of mammalian neutrophil plasma membrane NADPH oxidase) for 30 min prior to Cle addition blocked the NAD(P)H oxidase activity induced by Cle. These inhibitors also inhibited the release of H2C2, the synthesis of saponin, PAL activity and CHS accumulation. Our data revealed homology between plasma membrane NAD(P)H oxidases of mammalian neutrophil cells and ginseng suspension cells. They also indicated that deactivated NAD(P)H oxidases catalysed the release of H2O2 and that H2O2 was functioning as a second messenger stimulating PAL activity, saponin synthesis and hrgp transcription. Elevations of Ca2 + and protein phos-phorylation/dephosphorylation were required for this defense process. We propose that NAD(P)H oxidases mediate the processes of Cle-induced defense responses in ginseng suspensions, and postulate the existence of a signalling cascade including extracellular Cle stimulation, activation of plasma membrane NAD(P)H oxidases, release of H2O2, and the intracellular responses of metabolism and gene transcription in ginseng suspension cells.
基金supported by research grants from the National Natural Science Foundation of China(No.81101520)the National Basic Research Program of China(973 program)(No.2013CB910304 and 2012CB967004)
文摘Introduction:Oncogenic aaivation of the K-ras gene occurs in >90%of pancreatic ductal carcinoma and plays a critical role in the pathogenesis of this malignancy.Increase of reactive oxygen species(ROS) has also been observed in a wide spectrum of cancers.This study aimed to investigate the mechanistic association between K-ras-induced transformation and increased ROS stress and its therapeutic implications in pancreatic cancer.Methods:ROS level,NADPH oxidase(NOX) aaivity and expression,and cell invasion were examined in human pancreatic dua epithelial E6E7 cells transfeaed with K-ras^(G12V) compared with parental E6E7 cells.The cytotoxic effea and antitumor effect of capsaicin,a NOX inhibitor,were also tested in vitro and in vivo.Results:K-ras transfeaion caused activation of the membrane-associated redox enzyme NOX and elevated ROS generation through the phosphatidylinositol 3'-kinase(PI3K) pathway.Importantly,capsaicin preferentially inhibited the enzyme aaivity of NOX and induced severe ROS accumulation in K-ras-transformed cells compared with parental E6E7 cells.Furthermore,capsaicin effeaively inhibited cell proliferation,prevented invasiveness of /(-ras-transformed pancreatic cancer cells,and caused minimum toxicity to parental E6E7 cells.In vivo,capsaicin exhibited antitumor aaivity against pancreatic cancer and showed oxidative damage to the xenograft tumor cells.Conclusions:K-ras oncogenic signaling causes increased ROS stress through NOX,and abnormal ROS stress can selectively kill tumor cells by using NOX inhibitors.Our study provides a basis for developing a novel therapeutic strategy to effectively kill K-ras-transformed cells through a redox-mediated mechanism.
