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Molecular Carcinogenesis Jul 2017Quinone oxidoreductase (NQO1) functions as an important part of cellular antioxidant defense by detoxifying quinones, thus preventing the formation of reactive oxygen...
Quinone oxidoreductase (NQO1) functions as an important part of cellular antioxidant defense by detoxifying quinones, thus preventing the formation of reactive oxygen species. The aims of our study were 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 inceased 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. © 2006 Wiley-Liss, Inc.
PubMed: 28639725
DOI: 10.1002/mc.20199 -
Cancers Nov 2018In general, expression of transglutaminase 2 (TGase 2) is upregulated in renal cell carcinoma (RCC), resulting in p53 instability. Previous studies show that TGase 2...
In general, expression of transglutaminase 2 (TGase 2) is upregulated in renal cell carcinoma (RCC), resulting in p53 instability. Previous studies show that TGase 2 binds to p53 and transports it to the autophagosome. Knockdown or inhibition of TGase 2 in RCC induces p53-mediated apoptosis. Here, we screened a chemical library for TGase 2 inhibitors and identified streptonigrin as a potential therapeutic compound for RCC. Surface plasmon resonance and mass spectroscopy were used to measure streptonigrin binding to TGase 2. Mass spectrometry analysis revealed that streptonigrin binds to the N-terminus of TGase 2 (amino acids 95⁻116), which is associated with inhibition of TGase 2 activity in vitro and with p53 stabilization in RCC. The anti-cancer effects of streptonigrin on RCC cell lines were demonstrated in cell proliferation and cell death assays. In addition, a single dose of streptonigrin (0.2 mg/kg) showed marked anti-tumor effects in a preclinical RCC model by stabilizing p53. Inhibition of TGase 2 using streptonigrin increased p53 stability, which resulted in p53-mediated apoptosis of RCC. Thus, targeting TGase 2 may be a new therapeutic approach to RCC.
PubMed: 30463244
DOI: 10.3390/cancers10110455 -
PLoS Pathogens Jun 2022The Neisseria gonorrhoeae Type IV pilus is a multifunctional, dynamic fiber involved in host cell attachment, DNA transformation, and twitching motility. We previously...
The Neisseria gonorrhoeae Type IV pilus is a multifunctional, dynamic fiber involved in host cell attachment, DNA transformation, and twitching motility. We previously reported that the N. gonorrhoeae pilus is also required for resistance against hydrogen peroxide-, antimicrobial peptide LL-37-, and non-oxidative, neutrophil-mediated killing. We tested whether the hydrogen peroxide, LL-37, and neutrophil hypersensitivity phenotypes in non-piliated N. gonorrhoeae could be due to elevated iron levels. Iron chelation in the growth medium rescued a nonpiliated pilE mutant from both hydrogen peroxide- and antimicrobial peptide LL-37-mediated killing, suggesting these phenotypes are related to iron availability. We used the antibiotic streptonigrin, which depends on free cytoplasmic iron and oxidation to kill bacteria, to determine whether piliation affected intracellular iron levels. Several non-piliated, loss-of-function mutants were more sensitive to streptonigrin killing than the piliated parental strain. Consistent with the idea that higher available iron levels in the under- and non-piliated strains were responsible for the higher streptonigrin sensitivity, iron limitation by desferal chelation restored resistance to streptonigrin in these strains and the addition of iron restored the sensitivity to streptonigrin killing. The antioxidants tiron and dimethylthiourea rescued the pilE mutant from streptonigrin-mediated killing, suggesting that the elevated labile iron pool in non-piliated bacteria leads to streptonigrin-dependent reactive oxygen species production. These antioxidants did not affect LL-37-mediated killing. We confirmed that the pilE mutant is not more sensitive to other antibiotics showing that the streptonigrin phenotypes are not due to general bacterial envelope disruption. The total iron content of the cell was unaltered by piliation when measured using ICP-MS suggesting that only the labile iron pool is affected by piliation. These results support the hypothesis that piliation state affects N. gonorrhoeae iron homeostasis and influences sensitivity to various host-derived antimicrobial agents.
Topics: Bacterial Proteins; Fimbriae, Bacterial; Hydrogen Peroxide; Iron; Neisseria gonorrhoeae; Streptonigrin
PubMed: 35714158
DOI: 10.1371/journal.ppat.1010561 -
Microbiology Spectrum Aug 2023The bacterium Riemerella anatipestifer requires iron for growth, but the mechanism of iron uptake is not fully understood. In this study, we disrupted the Feo system and...
The bacterium Riemerella anatipestifer requires iron for growth, but the mechanism of iron uptake is not fully understood. In this study, we disrupted the Feo system and characterized its function in iron import in R. anatipestifer ATCC 11845. Compared to the parent strain, the growth of the Δ Δ and Δ strains was affected under Fe-limited conditions, since the absence of the system led to less intracellular iron than in the parent strain. In parallel, the Δ strain was shown to be less sensitive to streptonigrin, an antibiotic that requires free iron to function. The sensitivity of the Δ strain to hydrogen peroxide was also observed to be diminished compared with that of the parent strain, which could be related to the reduced intracellular iron content in the Δ strain. Further research revealed that and were directly regulated by iron through the Fur regulator and that the transcript levels of and were significantly increased in medium supplemented with 1 mM MnCl, 400 μM ZnSO, and 200 μM CuCl. Finally, it was shown that the Δ strain of R. anatipestifer ATCC 11845 was significantly impaired in its ability to colonize the blood, liver, and brain of ducklings. Taken together, these results demonstrated that FeoAB supports ferrous iron acquisition in R. anatipestifer and plays an important role in R. anatipestifer colonization. In Gram-negative bacteria, the Feo system is an important ferrous iron transport system. R. anatipestifer encodes an Feo system, but its function unknown. As iron uptake may be required for oxidative stress protection and virulence, understanding the contribution of iron transporters to these processes is crucial. This study showed that the Δ strain is debilitated in its ability to import iron and that its intracellular iron content was constitutively low, which enhanced the resistance of the deficient strain to HO. We were surprised to find that, in addition to responding to iron, the Feo system may play an important role in sensing manganese, zinc, and copper stress. The reduced colonization ability of the Δ strain also sheds light on the role of iron transporters in host-pathogen interactions. This study is important for understanding the cross talk between iron and other metal transport pathways, as well as the pathogenic mechanism in R. anatipestifer.
Topics: Virulence; Bacterial Proteins; Hydrogen Peroxide; Iron; Membrane Transport Proteins
PubMed: 37272830
DOI: 10.1128/spectrum.01373-23 -
Journal of Biomolecular Structure &... 2022Antibiotic resistance is a global concern. Two members of the bacterial genus namely, and have raised much concern in recent years because of their resistance to...
Antibiotic resistance is a global concern. Two members of the bacterial genus namely, and have raised much concern in recent years because of their resistance to multiple commonly used antibiotics. Identification of multidrug resistant and pan-drug resistant bacteria has propelled the search for new antibiotics that can act on unconventional targets. Researches are going on to find out the possibility of using bacterial ribonucleotide reductases as a novel target for antibiotic development. Through evaluations, this study aims for characterization and functional annotation of ribonucleotide reductase enzymes of and . Binding affinities with these enzymes of the compounds that have shown promising results in inhibiting growth by acting on its ribonucleotide reductase were also assessed by molecular docking and dynamics simulations. Insights from this study will help in battling these infections in the near future. Communicated by Ramaswamy H. Sarma.
Topics: Humans; Ribonucleotide Reductases; Molecular Docking Simulation; Streptonigrin; Flavobacteriaceae Infections; Genome, Bacterial; Phylogeny; Anti-Bacterial Agents
PubMed: 34048660
DOI: 10.1080/07391102.2021.1930166 -
Molecules (Basel, Switzerland) Nov 2019Natural 5,8-quinolinedione antibiotics exhibit a broad spectrum of activities including anticancer, antibacterial, antifungal, and antimalarial activities. The... (Review)
Review
Natural 5,8-quinolinedione antibiotics exhibit a broad spectrum of activities including anticancer, antibacterial, antifungal, and antimalarial activities. The structure-activity research showed that the 5,8-quinolinedione scaffold is responsible for its biological effect. The subject of this review report is a presentation of the pharmacological activity of synthetic 5,8-quinolinedione compounds containing different groups at C-6 and/or C-7 positions. The relationship between the activity and the mechanism of action is included if these data have been included in the original literature. The review mostly covers the period between 2000 and 2019. Previously published literature data were used to present historical points.
Topics: Molecular Structure; Quinolines; Streptonigrin; Structure-Activity Relationship
PubMed: 31739496
DOI: 10.3390/molecules24224115 -
Molecular Oral Microbiology Dec 2016SloR, a 25-kDa metalloregulatory protein in Streptococcus mutans modulates the expression of multiple genes, including the sloABC operon that encodes essential Mn...
SloR, a 25-kDa metalloregulatory protein in Streptococcus mutans modulates the expression of multiple genes, including the sloABC operon that encodes essential Mn transport and genes that promote cariogenesis. In this study, we report on SloC- and SloR-deficient strains of S. mutans (GMS284 and GMS584, respectively) that demonstrate compromised survivorship compared with their UA159 wild-type progenitor and their complemented strains (GMS285 and GMS585, respectively), when challenged with streptonigrin and/or in growth competition experiments. The results of streptonigrin assays revealed significantly larger zones of inhibition for GMS584 than for either UA159 or GMS585, indicating weakened S. mutans survivorship in the absence of SloR. Competition assays revealed a compromised ability for GMS284 and GMS584 to survive peroxide challenge compared with their SloC- and SloR-proficient counterparts. These findings are consistent with a role for SloC and SloR in S. mutans aerotolerance. We also predicted differential expression of oxidative stress tolerance genes in GMS584 versus UA159 and GMS585 when grown aerobically. The results of quantitative RT-PCR experiments revealed S. mutans sod, tpx, and sloC expression that was upregulated in GMS584 compared with UA159 and GMS585, indicating that the impact of oxidative stress on S. mutans is more severe in the absence of SloR than in its presence. The results of electrophoretic mobility shift assays indicate that SloR does not bind to the sod or tpx promoter regions directly, implicating intermediaries that may arbitrate the SloR response to oxidative stress.
Topics: Bacterial Proteins; DNA, Bacterial; Gene Expression Regulation, Bacterial; Genetic Complementation Test; Hydrogen Peroxide; Metals; Mutation; Oxidative Stress; Streptococcus mutans; Streptonigrin; Superoxide Dismutase-1; Virulence
PubMed: 26577188
DOI: 10.1111/omi.12147 -
Journal of Microbiology, Immunology,... Dec 2022Klebsiella pneumoniae is a gram-negative opportunistic pathogen that causes diseases mostly in immunocompromised individuals. Recently, hypervirulent K. pneumoniae...
BACKGROUND
Klebsiella pneumoniae is a gram-negative opportunistic pathogen that causes diseases mostly in immunocompromised individuals. Recently, hypervirulent K. pneumoniae strains also cause severe disease in healthy individuals. Capsular polysaccharide (CPS) is the major virulence determinant in hypervirulent K. pneumoniae and protects the cell against the bactericidal activity of the immune system. Gallic acid (GA), a natural phenolic compound, is known to exhibit wide spectrum antibacterial activity; however, its effect on hypervirulent K. pneumoniae remains largely unresolved. We aimed to identify the effects of GA on CPS biosynthesis in hypervirulent K. pneumoniae.
METHODS
Antibacterial activity of GA was evaluated by counting colonies. CPS amount was determined by glucuronic acid content. The transcriptions of cps gene cluster were measured by quantitative real time PCR (qRT-PCR) and the β-galactosidase activity. The effect of GA on the resistance of K. pneumoniae to streptonigrin (SNG), an iron-activated antibiotic, was evaluated. The effect of GA on the resistance of K. pneumoniae to serum killing and phagocytosis by macrophages was observed.
RESULTS
GA inhibited the growth and CPS biosynthesis in K. pneumoniae. GA may affect the iron availability in K. pneumoniae, thus possibly repressing the cps transcription. In addition, GA reduced the resistance of K. pneumoniae to serum killing and enhanced its susceptibility to phagocytosis.
CONCLUSION
GA possesses bactericidal activity and inhibits the CPS biosynthesis in hypervirulent K. pneumoniae, thereby facilitating pathogen clearance by the host immune system. Therefore, GA may represent a promising strategy for the prevention or treatment of patients with hypervirulent K. pneumoniae infections.
Topics: Humans; Klebsiella pneumoniae; Gallic Acid; Virulence Factors; Anti-Bacterial Agents; Iron; Klebsiella Infections
PubMed: 34326026
DOI: 10.1016/j.jmii.2021.07.002 -
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 -
Archives of Biochemistry and Biophysics Sep 2022Several compounds have been found capable of diverting the electron flow in Escherichia coli and thus causing increased intracellular production of O and HO. One...
Several compounds have been found capable of diverting the electron flow in Escherichia coli and thus causing increased intracellular production of O and HO. One indication of this electron-shunting action was increased cyanide-resistant respiration and one cellular response was increased biosynthesis of the manganese-containing superoxide dismutase and of catalase. Blocking cytochrome oxidase with cyanide or azide increased the electron flow available for reduction of paraquat and presumably of the other exogenous compounds tested and thus increased their biological effects. Paraquat, pyocyanine, phenazine methosulfate, streptonigrin, juglone, menadione, plumbagin, methylene blue, and azure C were all effective in elevating intracellular production of O and HO. The effect of alloxan appeared paradoxical in that it increased cyanide-resistant respiration without significantly increasing the cell content of the manganese-superoxide dismutase and with only a small effect on the level of catalase. The alloxan effect on cyanide-resistant respiration was artifactual and was due to an oxygen-consuming reaction between alloxan and cyanide, rather than to a diversion of the intracellular electron flow. With paraquat as a representative electron-shunting compound, the increase in biosynthesis of the manganese-superoxide dismutase was prevented by inhibitors of transcription or of translation, but not by an inhibitor of replication. The increase in this enzyme activity, caused by paraquat and presumably by the other compounds, was thus due to de novo enzyme synthesis activated or derepressed at the level of transcription.
Topics: Alloxan; Catalase; Cyanides; Escherichia coli; Hydrogen Peroxide; Manganese; Oxidation-Reduction; Oxygen; Paraquat; Superoxide Dismutase; Superoxides
PubMed: 35660299
DOI: 10.1016/j.abb.2022.109229