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Journal of Experimental & Clinical... Apr 2019Abnormal expression or distribution of connexin 32 (Cx32) is associated with hepatocarcinogenesis, but the role of Cx32 and the underlying mechanisms are still unclear.
BACKGROUND
Abnormal expression or distribution of connexin 32 (Cx32) is associated with hepatocarcinogenesis, but the role of Cx32 and the underlying mechanisms are still unclear.
METHODS
The expression level of Cx32 in 96 hepatocellular carcinoma (HCC) specimens was determined using western blotting and immunohistochemistry. The correlation between Cx32 expression and clinicopathological parameters was analyzed. The cell apoptosis rate was examined using flow cytometry and western blotting. The role of Cx32 in the Src kinase and epidermal growth factor receptor (EGFR) signaling pathways was measured by quantitative real-time PCR, western blotting and coimmunoprecipitation (CO-IP). The effect of Cx32 overexpression on the streptonigrin (SN)-induced tumor growth suppression and apoptosis was assessed in nude mice.
RESULTS
Our study showed that overexpressed Cx32 accumulated in the cytoplasm and that Cx32-containing gap junctions (GJs) were nearly absent in HCC specimens. Upregulated Cx32 expression was highly correlated with advanced tumor-node-metastasis (TNM) stage and poor tumor differentiation and was an independent predictive marker for poor prognosis in HCC. Overexpression of Cx32 significantly inhibited SN-induced apoptosis by activating the EGFR signaling pathway in vitro and in vivo. Moreover, the expression levels of Cx32 and EGFR were positively correlated in HCC specimens. The CO-IP experiments demonstrated that Cx32 could bind to Src kinase, and the western blotting results revealed that Cx32 increased the levels of EGFR and p-EGFR by upregulating Src expression.
CONCLUSION
The present study demonstrated that overexpressed and internalized Cx32 was associated with advanced TNM stage and poor tumor differentiation and predicted poor prognosis in HCC. Cx32 facilitated HCC progression by blocking chemotherapy-induced apoptosis in vitro and in vivo via interacting with Src and thus promoting the phosphorylation of EGFR, subsequently activating the EGFR signaling pathway. Cx32 may be a potential biomarker and a new therapeutic target for HCC.
Topics: Adult; Aged; Animals; Apoptosis; Carcinoma, Hepatocellular; Connexins; ErbB Receptors; Humans; Liver Neoplasms; Male; Mice; Middle Aged; Signal Transduction; Transfection; Young Adult; Gap Junction beta-1 Protein
PubMed: 30947731
DOI: 10.1186/s13046-019-1142-y -
Cells Jan 2021Circulating extracellular DNA (ecDNA) is known to worsen the outcome of many diseases. ecDNA released from neutrophils during infection or inflammation is present in the...
Circulating extracellular DNA (ecDNA) is known to worsen the outcome of many diseases. ecDNA released from neutrophils during infection or inflammation is present in the form of neutrophil extracellular traps (NETs). It has been shown that higher ecDNA concentration occurs in a number of inflammatory diseases including inflammatory bowel disease (IBD). Enzymes such as peptidyl arginine deiminases (PADs) are crucial for NET formation. We sought to describe the dynamics of ecDNA concentrations and fragmentation, along with NETosis during a mouse model of chemically induced colitis. Plasma ecDNA concentration was highest on day seven of dextran sulfate sodium (DSS) intake and the increase was time-dependent. This increase correlated with the percentage of cells undergoing NETosis and other markers of disease activity. Relative proportion of nuclear ecDNA increased towards more severe colitis; however, absolute amount decreased. In colon explant medium, the highest concentration of ecDNA was on day three of DSS consumption. Early administration of PAD4 inhibitors did not alleviate disease activity, but lowered the ecDNA concentration. These results uncover the biological characteristics of ecDNA in IBD and support the role of ecDNA in intestinal inflammation. The therapeutic intervention aimed at NETs and/or nuclear ecDNA has yet to be fully investigated.
Topics: Animals; Biomarkers; Colitis; DNA; DNA, Mitochondrial; Deoxyribonucleases; Dextran Sulfate; Endoscopy; Extracellular Space; Extracellular Traps; Inflammation; Intestinal Mucosa; Intestines; Mice, Inbred C57BL; Ornithine; Protein-Arginine Deiminase Type 4; Severity of Illness Index; Streptonigrin; Mice
PubMed: 33418977
DOI: 10.3390/cells10010081 -
Marine Drugs Mar 2019Two new piperazine-triones lansai E and F (, ), together with four known secondary metabolites lansai D (), 1--methyl-()-albonoursin (), imidazo[4,5-]-1,2,4-triazine (),...
Two new piperazine-triones lansai E and F (, ), together with four known secondary metabolites lansai D (), 1--methyl-()-albonoursin (), imidazo[4,5-]-1,2,4-triazine (), and streptonigrin () were isolated from a deep-sea-derived sp. strain SMS636. The structures of the isolated compounds were confirmed by comprehensive spectroscopic analysis, including HRESIMS, 1D and 2D NMR. Compound exhibited moderate antibacterial activities against and methicillin resistant (MRSA) with Minimum Inhibitory Concentration (MIC) values of 12.5 and 25 μg/mL, respectively. Compound displayed significant antibacterial activities against , MRSA and Bacillus Calmette-Guérin (BCG) with MIC values of 0.78, 0.78 and 1.25 μg/mL, respectively.
Topics: Anti-Bacterial Agents; Candida albicans; Escherichia coli; Methicillin-Resistant Staphylococcus aureus; Microbial Sensitivity Tests; Piperazine; Pseudomonas aeruginosa; Staphylococcus aureus; Streptomycetaceae
PubMed: 30901830
DOI: 10.3390/md17030186 -
The Journal of Antibiotics Apr 1986Though all the streptonigrin derivatives with modifications in the carboxyl group on C2' were active as electron acceptors in the oxidation of NADH by Clostridium...
Though all the streptonigrin derivatives with modifications in the carboxyl group on C2' were active as electron acceptors in the oxidation of NADH by Clostridium kluyveri diaphorase as well as streptonigrin, the glycine derivative did not show any marked effect on the KCN-insensitive oxidation of glutamate by rat liver mitochondria, suggesting a poor membrane transport of the glycine derivative. Sakyomicin A also induced the KCN-insensitive oxidation of glutamate by mitochondria, while a trace activity was observed by mitomycin C and the effect of doxorubicin was negligible. Like streptonigrin, the autoxidation of a reduced form (hydroquinone) of sakyomicin A to a quinone accompanied the generation of H2O2. However, exogenous NADH was oxidized by mitochondria in the presence of sakyomicin A but not streptonigrin.
Topics: Animals; Anti-Bacterial Agents; Benzoquinones; Edetic Acid; Glutamates; Glutamic Acid; In Vitro Techniques; Mitochondria, Liver; NAD; Oxidation-Reduction; Oxygen Consumption; Quinone Reductases; Quinones; Rats; Streptonigrin
PubMed: 2872195
DOI: 10.7164/antibiotics.39.550 -
Molecules (Basel, Switzerland) Sep 2022Hybrids 1,4-quinone with quinoline were obtained by connecting two active structures through an oxygen atom. This strategy allows to obtain new compounds with a high...
Hybrids 1,4-quinone with quinoline were obtained by connecting two active structures through an oxygen atom. This strategy allows to obtain new compounds with a high biological activity and suitable bioavailability. Newly synthesized compounds were characterized by various spectroscopic methods. The enzymatic assay used showed that these compounds were a suitable DT-diaphorase (NQO1) substrates as evidenced by increasing enzymatic conversion rates relative to that of streptonigrin. Hybrids were tested in vitro against a panel of human cell lines including melanoma, breast, and lung cancers. They showed also a high cytotoxic activity depending on the type of 1,4-quinone moiety and the applied tumor cell lines. It was found that cytotoxic activity of the studied hybrids was increasing against the cell lines with higher NQO1 protein level, such as breast (MCF-7 and T47D) and lung (A549) cancers. Selected hybrids were tested for the transcriptional activity of the gene encoding a proliferation marker (H3 histone), cell cycle regulators (p53 and p21) and the apoptosis pathway (BCL-2 and BAX). The molecular docking was used to examine the probable interaction between the hybrids and NQO1 protein.
Topics: Antineoplastic Agents; Apoptosis; Benzoquinones; Cell Line, Tumor; Drug Screening Assays, Antitumor; Histones; Humans; Hydroxyquinolines; Molecular Docking Simulation; NAD(P)H Dehydrogenase (Quinone); Oxygen; Quinolines; Quinones; Streptonigrin; Tumor Suppressor Protein p53; bcl-2-Associated X Protein
PubMed: 36234741
DOI: 10.3390/molecules27196206 -
Analysis of the activities of RAD54, a SWI2/SNF2 protein, using a specific small-molecule inhibitor.The Journal of Biological Chemistry Nov 2013RAD54, an important homologous recombination protein, is a member of the SWI2/SNF2 family of ATPase-dependent DNA translocases. In vitro, RAD54 stimulates RAD51-mediated...
RAD54, an important homologous recombination protein, is a member of the SWI2/SNF2 family of ATPase-dependent DNA translocases. In vitro, RAD54 stimulates RAD51-mediated DNA strand exchange and promotes branch migration of Holliday junctions. It is thought that an ATPase-dependent DNA translocation is required for both of these RAD54 activities. Here we identified, by high-throughput screening, a specific RAD54 inhibitor, streptonigrin (SN), and used it to investigate the mechanisms of RAD54 activities. We found that SN specifically targets the RAD54 ATPase, but not DNA binding, through direct interaction with RAD54 and generation of reactive oxygen species. Consistent with the dependence of branch migration (BM) on the ATPase-dependent DNA translocation of RAD54, SN inhibited RAD54 BM. Surprisingly, the ability of RAD54 to stimulate RAD51 DNA strand exchange was not significantly affected by SN, indicating a relatively smaller role of RAD54 DNA translocation in this process. Thus, the use of SN enabled us to identify important differences in the effect of the RAD54 ATPase and DNA translocation on two major activities of RAD54, BM of Holliday junctions and stimulation of DNA pairing.
Topics: Adenosine Triphosphatases; Antibiotics, Antineoplastic; DNA Helicases; DNA Repair Enzymes; DNA, Cruciform; DNA, Fungal; Homologous Recombination; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; Streptonigrin; Transcription Factors
PubMed: 24043618
DOI: 10.1074/jbc.M113.502195 -
Journal of Cell Science Sep 2017This study was designed to identify bioactive compounds that alter the cellular shape of the fission yeast by affecting functions involved in the cell cycle or cell...
This study was designed to identify bioactive compounds that alter the cellular shape of the fission yeast by affecting functions involved in the cell cycle or cell morphogenesis. We used a multidrug-sensitive fission yeast strain, SAK950 to screen a library of 657 actinomycete bacteria and identified 242 strains that induced eight different major shape phenotypes in These include the typical cell cycle-related phenotype of elongated cells, and the cell morphology-related phenotype of rounded cells. As a proof of principle, we purified four of these activities, one of which is a novel compound and three that are previously known compounds, leptomycin B, streptonigrin and cycloheximide. In this study, we have also shown novel effects for two of these compounds, leptomycin B and cycloheximide. The identification of these four compounds and the explanation of the phenotypes in terms of their known, or predicted bioactivities, confirm the effectiveness of this approach.
Topics: Actinomyces; Biological Products; Cell Shape; Checkpoint Kinase 1; Cycloheximide; DNA Damage; Drug Evaluation, Preclinical; Fatty Acids, Unsaturated; Phenotype; Schizosaccharomyces; Spectrometry, Mass, Electrospray Ionization
PubMed: 28775153
DOI: 10.1242/jcs.194571 -
Antimicrobial Agents and Chemotherapy Oct 1987The quinone antibiotic streptonigrin is believed to kill bacteria by promoting formation of oxygen radicals. This antibiotic has also been used to select resistant...
The quinone antibiotic streptonigrin is believed to kill bacteria by promoting formation of oxygen radicals. This antibiotic has also been used to select resistant bacterial mutants, some of which vary in iron utilization. We examined the effects of streptonigrin on Neisseria gonorrhoeae and several types of gonococcal mutants. Streptonigrin (0.025 microgram/ml) efficiently killed gonococcal strain FA1090, and this effect depended on iron. Streptonigrin-resistant mutant FA6271 had normal iron uptake but was moderately deficient in total iron. Resistance most likely resulted from failure of FA6271 to divert electrons to streptonigrin, as demonstrated by a reduction in KCN-insensitive respiration (a hallmark of the action of quinones) and superoxide formation. Other mutants selected for inability to use human iron-binding proteins (strains FA6273 and FA6275) had no increase in streptonigrin MIC and no decrease in KCN-insensitive respiration. Mutants did not demonstrate an increase in superoxide dismutase or catalase. Streptonigrin killing of gonococci depended on a reaction(s) in which extracellular iron was important, presumably because iron was required for catalysis of hydroxyl radical. The results suggest that a membrane component may be a target for the actions of streptonigrin.
Topics: Catalase; Drug Resistance, Microbial; Free Radicals; Indicators and Reagents; Iron; Mutation; Neisseria gonorrhoeae; Oxygen Consumption; Streptonigrin; Superoxides
PubMed: 2829710
DOI: 10.1128/AAC.31.10.1507 -
Emerging Microbes & Infections 2019Transition metals are nutrients essential for life. However, an excess of metals can be toxic to cells, and host-imposed metal toxicity is an important mechanism for...
Transition metals are nutrients essential for life. However, an excess of metals can be toxic to cells, and host-imposed metal toxicity is an important mechanism for controlling bacterial infection. Accordingly, bacteria have evolved metal efflux systems to maintain metal homeostasis. Here, we established that PmtA functions as a ferrous iron [Fe(II)] and cobalt [Co(II)] efflux pump in , an emerging zoonotic pathogen responsible for severe infections in both humans and pigs. expression is induced by Fe(II), Co(II), and nickel [Ni(II)], whereas PmtA protects against Fe(II) and ferric iron [Fe(III)]-induced bactericidal effect, as well as Co(II) and zinc [Zn(II)]-induced bacteriostatic effect. In the presence of elevated concentrations of Fe(II) and Co(II), Δ accumulates high levels of intracellular iron and cobalt, respectively. Δ is also more sensitive to streptonigrin, a Fe(II)-activated antibiotic. Furthermore, growth defects of Δ under Fe(II) or Co(II) excess conditions can be alleviated by manganese [Mn(II)] supplementation. Finally, PmtA plays a role in tolerance to HO-induced oxidative stress, yet is not involved in the virulence of in mice. Together, these data demonstrate that PmtA acts as a Fe(II) and Co(II) efflux pump, and contributes to oxidative stress resistance.
Topics: Bacterial Proteins; Biological Transport, Active; Cobalt; Gene Deletion; Iron; Methyltransferases; Streptococcus suis; Trace Elements
PubMed: 31469035
DOI: 10.1080/22221751.2019.1660233 -
Molecular Carcinogenesis Aug 2005NAD(P)H:quinone oxidoreductase (NQO1) functions as an important part of cellular antioxidant defense by detoxifying quinones, thus preventing the formation of reactive...
NAD(P)H:quinone oxidoreductase (NQO1) functions as an important part of cellular antioxidant defense by detoxifying quinones, thus preventing the formation of reactive oxygen species (ROS). The aim of our study was to determine if NQO1 is elevated in pancreatic cancer specimens and pancreatic cancer cell lines and if so, would compounds previously demonstrated to redox cycle with NQO1 be effective in killing pancreatic cancer cells. Immunohistochemistry of resected pancreatic specimens demonstrated an increased immunoreactivity for NQO1 in pancreatic cancer and pancreatic intraepithelial neoplasia (PanIN) specimens versus normal human pancreas. Immunocytochemistry and Western immunoblots demonstrated increased immunoreactivity in pancreatic cancer cells when compared to a near normal immortalized human pancreatic ductal epithelial cell line and a colonic epithelial cell line. Streptonigrin, a compound known to cause redox cycling in the presence of NQO1, decreased clonogenic survival and decreased anchorage-independent growth in soft agar. Streptonigrin had little effect on cell lines with absent or reduced levels of NQO1. The effects of streptonigrin were reversed in pancreatic cancer cells pretreated with dicumarol, a known inhibitor of NQO1. NQO1 may be a therapeutic target in pancreatic cancer where survival is measured in months.
Topics: Agar; Blotting, Western; Cell Proliferation; Clone Cells; Humans; Immunohistochemistry; NAD(P)H Dehydrogenase (Quinone); Pancreatic Neoplasms; Phenotype; Streptonigrin; Tissue Array Analysis; Tumor Cells, Cultured
PubMed: 16003741
DOI: 10.1002/mc.20107