RESUMO
PURPOSE: To investigate the role of PRDX2 in esophageal carcinoma (ESCA). METHODS: The expression of PRDX2 was detected in ESCA tissues. And PRDX2 expression in two ESCA cell lines was knocked down. Cell proliferation, metastasis and invasion were detected in these cells. RESULTS: Here, we found that PRDX2 expression was significantly increased in ESCA tissues and was associated with a poor prognosis in ESCA patients. In addition, PRDX2 expression was significantly associated with pathological grading, infiltration degree and 5-year survival time in ESCA patients. Next, we knocked down PRDX2 expression by PRDX2-shRNA transfection in two ESCA cell lines, Eca-109 and TE-1. Proliferation analysis indicated that in vitro PRDX2 knockdown decreased growth and clone formation of ESCA cells. Scratch and transwell assays indicated that cell migration and invasion were significantly inhibited by PRDX2 knockdown. In addition, PRDX2 knockdown inhibited cell cycle of ESCA cells and down-regulated Cyclin D1-CDK4/6. Moreover, PRDX2 knockdown regulated proteins involved in mitochondrial-dependent apoptosis, including increased Bax and Caspase9/3 and decreased Bcl2. Mechanism investigation indicated that PRDX2 knockdown led to inactivation of Wnt/ß-catenin and AKT pathways. CONCLUSIONS: Our data suggest that PRDX2 may function as an oncogene in the development of ESCA via regulating Wnt/ß-catenin and AKT pathways. Our study fills a gap in the understanding of the role of PRDX2 in ESCA and provides a potential target for ESCA treatment.
Assuntos
Neoplasias Esofágicas/etiologia , Carcinoma de Células Escamosas do Esôfago/etiologia , Peroxirredoxinas/fisiologia , Proteínas Proto-Oncogênicas c-akt/fisiologia , Via de Sinalização Wnt/fisiologia , Apoptose , Pontos de Checagem do Ciclo Celular , Linhagem Celular Tumoral , Movimento Celular , Proliferação de Células , Neoplasias Esofágicas/patologia , Carcinoma de Células Escamosas do Esôfago/patologia , Humanos , Peroxirredoxinas/análiseRESUMO
B cell malignancies are classified according to the postulated differentiation stage of the originating cell. During differentiation, structural and molecular changes occur to support massive processing of immunoglobulin in the endoplasmic reticulum (ER) of plasma cells at the final stage. When overloaded, the ER generates unfolded proteins and hydrogen peroxide (H2O2), which may cause cell death. Peroxiredoxins (Prxs) I and IV belong to a family of proteins able to catalyze peroxide detoxification. Here, we investigated a potential association of these enzymes with immunoglobulin production in B cell neoplasms. Our results demonstrated that the expression of Prx IV was induced as cells became competent to synthesize immunoglobulin light chains, as observed by immunohistochemistry in tissue sections of B cell neoplasms and also by qPCR and Western blotting analyses in malignant B cell lines. Prx I was frequently highly expressed, indicating additional regulatory processes besides ER activity. Results obtained exclusively with myeloma cells have shown that expression of Prxs I and IV, both at mRNA and protein levels, was associated with light chain secretion quantified by ELISA. We suggest that Prxs I and IV may provide survival advantages for terminally differentiated neoplastic B cells by the elimination of H2O2 and, in the case of Prx IV, by the conversion of this toxic in a functional agent driving oxidative protein folding in the ER. In this sense, multiple myeloma and lymphomas demonstrated to synthesize immunoglobulin chains may benefit from strategic therapies targeting the adaptive pathway to ER stress, including inhibition of Prxs I and IV activity.
Assuntos
Imunoglobulinas/biossíntese , Mieloma Múltiplo/enzimologia , Peroxirredoxinas/fisiologia , Linhagem Celular Tumoral , Proteínas de Ligação a DNA/metabolismo , Retículo Endoplasmático/metabolismo , Humanos , Peróxido de Hidrogênio/metabolismo , Imuno-Histoquímica , Mieloma Múltiplo/imunologia , Peroxirredoxinas/análise , Peroxirredoxinas/antagonistas & inibidores , Peroxirredoxinas/genética , Fatores de Transcrição de Fator Regulador X , Fatores de Transcrição/metabolismoRESUMO
Mycoplasma hyopneumoniae is the causative agent of porcine enzootic pneumonia, which affects pig farms worldwide, causing heavy economic losses. In the infection process, this bacterium is exposed to reactive oxygen species (ROS) from its own metabolism or generated by the host as one of the strategies used to neutralize the pathogen. Although the presence of classical antioxidant enzymes would be expected in M. hyopneumoniae, important genes directly related to protection against ROS, such as superoxide dismutase, catalases and glutathione peroxidase, have not been identified by sequence homology in the genome sequence annotation. Among the few identified M. hyopneumoniae genes coding for proteins possibly involved with suppression of ROS-mediated damage, one (tpx) coding for a peroxiredoxin (MhPrx) has been recognized. The sequence and phylogenetic analyses perfomed in this study indicate that MhPrx is closely related to the atypical 2-Cys peroxiredoxin subfamily, although it has only one cysteine in its sequence. The MhPrx coding DNA sequence was cloned and expressed in Escherichia coli to produce a recombinant MhPrx (rMhPrx), which was purified and used to immunize mice and produce an anti-MhPrx polyclonal antiserum. Probing of M. hyopneumoniae extracts with this antiserum demonstrated that MhPrx is expressed in all three tested strains (J, 7422 and 7448). Cross-linking assays and size-exclusion chromatography indicate that rMhPrx forms dimers, as has been established for atypical 2-Cys peroxiredoxins. Furthermore, a metal-catalysed oxidation system was used to assay the activity of rMhPrx, showing that it can protect DNA from ROS-mediated damage and may play an essential role during infection.
Assuntos
Peróxido de Hidrogênio/antagonistas & inibidores , Mycoplasma hyopneumoniae/fisiologia , Peroxirredoxinas/fisiologia , Espécies Reativas de Oxigênio/antagonistas & inibidores , Sequência de Aminoácidos , Animais , Clonagem Molecular , DNA/metabolismo , Dano ao DNA , DNA Bacteriano/genética , Dimerização , Escherichia coli/genética , Expressão Gênica , Camundongos , Camundongos Endogâmicos BALB C , Dados de Sequência Molecular , Mycoplasma hyopneumoniae/genética , Peroxirredoxinas/genética , Filogenia , Homologia de Sequência de AminoácidosRESUMO
Peroxiredoxins are receiving increasing attention as defenders against oxidative damage and sensors of hydrogen peroxide-mediated signaling events. In the yeast Saccharomyces cerevisiae, deletion of one or more isoforms of the peroxiredoxins is not lethal but compromises genome stability by mechanisms that remain under scrutiny. Here, we show that cytosolic peroxiredoxin-null cells (tsa1Deltatsa2Delta) are more resistant to hydrogen peroxide than wild-type (WT) cells and consume it faster under fermentative conditions. Also, tsa1Deltatsa2Delta cells produced higher yields of the 1-hydroxyethyl radical from oxidation of the glucose metabolite ethanol, as proved by spin-trapping experiments. A major role for Fenton chemistry in radical formation was excluded by comparing WT and tsa1Deltatsa2Delta cells with respect to their levels of total and chelatable metal ions and of radical produced in the presence of chelators. The main route for 1-hydroxyethyl radical formation was ascribed to the peroxidase activity of Cu,Zn-superoxide dismutase (Sod1), whose expression and activity increased approximately 5- and 2-fold, respectively, in tsa1Deltatsa2Delta compared with WT cells. Accordingly, overexpression of human Sod1 in WT yeasts led to increased 1-hydroxyethyl radical production. Relevantly, tsa1Deltatsa2Delta cells challenged with hydrogen peroxide contained higher levels of DNA-derived radicals and adducts as monitored by immuno-spin trapping and incorporation of (14)C from glucose into DNA, respectively. The results indicate that part of hydrogen peroxide consumption by tsa1Deltatsa2Delta cells is mediated by induced Sod1, which oxidizes ethanol to the 1-hydroxyethyl radical, which, in turn, leads to increased DNA damage. Overall, our studies provide a pathway to account for the hypermutability of peroxiredoxin-null strains.
Assuntos
DNA/metabolismo , Etanol/metabolismo , Peróxido de Hidrogênio/farmacologia , Peroxirredoxinas/fisiologia , Saccharomyces cerevisiae/metabolismo , Superóxido Dismutase/metabolismo , Animais , Sobrevivência Celular/efeitos dos fármacos , Cobre/análise , Dano ao DNA , Instabilidade Genômica , Humanos , Ferro/análise , Camundongos , Oxirredução , Saccharomyces cerevisiae/efeitos dos fármacos , Saccharomyces cerevisiae/crescimento & desenvolvimento , Espectrofotometria Atômica , Superóxido Dismutase-1 , Zinco/análiseRESUMO
Peroxiredoxins catalytically reduce peroxynitrite to nitrite. The peroxidatic cysteine of peroxiredoxins reacts rapidly with peroxynitrite. The rate constant of that reaction can be measured using a stopped flow spectrophotometer either directly by following peroxynitrite disappearance in the region of 300 to 310 nm using an initial rate approach or steady-state measurements or by competition with a reaction of known rate constant. The reactions used to compete with peroxiredoxins include the oxidation of Mn(III)porphyrins and horseradish peroxidase by peroxynitrite. Additionally, a method is described in which a hydroperoxide competes with peroxynitrite for the oxidation of peroxiredoxin. Moreover, a fluorescent technique for determining the kinetics of thioredoxin-mediated peroxiredoxin reduction, closing the catalytic cycle, is also described. All methods reviewed provide reliable values of rate constants and a combination of them can be used to provide further reassurance; applicability and advantages of the different methodologies are discussed.