bims-noxint Biomed News
on NADPH oxidases in tumorigenesis
Issue of 2020‒04‒05
eight papers selected by
Laia Caja Puigsubira
Uppsala University

  1. Clin Sci (Lond). 2020 Mar 30. pii: CS20191235. [Epub ahead of print]
    Huang Y, Li Y, Lou A, Wang G, Hu Y, Zhang Y, Huang W, Wang J, Li Y, Zhu X, Chen T, Lin J, Meng Y, Li X.
      Angiotensin II (Ang II) has been reported to aggravate hepatic fibrosis by inducing NADPH oxidase (NOX)-dependent oxidative stress. Alamandine protects against fibrosis by counteracting Ang II via the MrgD receptor, though the effects of alamandine on hepatic fibrosis remain unknown. Autophagy activated by reactive oxygen species (ROS) is a novel mechanism of hepatic fibrosis. However, whether autophagy is involved in the regulation of Ang II-induced hepatic fibrosis still requires investigation. We explored the effect of alamandine on hepatic fibrosis via regulation of autophagy by redox balance modulation. In vivo, alamandine reduced ccl4-induced hepatic fibrosis, H2O2 content, protein levels of NOX4 and autophagy impairment. In vitro, Ang II treatment elevated NOX4 protein expression and ROS production along with upregulation of the ACE/Ang II/AT1R axis. These changes resulted in the accumulation of impaired autophagosomes in hepatic stellate cells (HSCs). Treatment withtheNOX4 inhibitor VAS2870, ROS scavenger N-acetylcysteine, and NOX4 small interfering RNA (siRNA) inhibited Ang II-induced autophagy and collagen synthesis. Alamandine shifted the balance of RAS toward the ACE2/alamandine/MrgD axis, and inhibited both Ang II-induced ROS and autophagy activation, leading to attenuation of HSCs migration or collagen synthesis. In summary, alamandine attenuated liver fibrosis by regulating autophagy induced by NOX4-dependent ROS.
    Keywords:  Alamandine; Angiotensin II; Autophagy; Hepatic fibrosis; NADPH oxidase; Oxidative stress
  2. Mol Metab. 2020 Feb 28. pii: S2212-8778(20)30041-7. [Epub ahead of print]36 100968
    Shi Q, Lee DY, Féliers D, Abboud HE, Bhat MA, Gorin Y.
      OBJECTIVE: Glomerular injury is a prominent pathological feature of diabetic kidney disease (DKD). Constitutively active NADPH oxidase 4 (Nox4) is a major source of reactive oxygen species that mediates hyperglycemia-induced mesangial cell (MC) fibrotic injury. However, the mechanism that Nox4 utilizes to achieve its biological outcome remains elusive, and the signaling pathways that regulate this isoform oxidase are not well understood. Here, our goal is to study the detailed mechanism by which NAPDH oxidase 4 (Nox4) is post-transcriptionally regulated in MC during diabetic pathology.METHODS: We studied the protein expression of HuR, Nox4 and matrix proteins by western blotting, while we assessed the mRNA stability of Nox4 by RT-PCR and polysomal assay, examined in vitro cultured glomerular mesangial cells treated by high glucose (HG) and diabetic animal induced by STZ. The binding assay between HuR and the Nox4 promoter was done by immuno-precipiating with HuR antibody and detecting the presence of Nox4 mRNA, or by pull-down by using biotinlyated labeled Nox4 promoter RNA and detecting the presence of the HuR protein. The binding was also confirmed in MCs where Nox4 promoter-containing luciferage constructs were transfected. ROS levels were measured with DHE/DCF dyes in cells, or lucigenin chemiluminescence for Nox enzymatic levels, or HPLC assay for superoxide. HuR protein was inhibited by antisense oligo that utilized osmotic pumps for continuous delivery in animal models. The H1bAc1 ratio was measured by an ELISA kit for mice.
    RESULTS: We demonstrate that in MCs, high glucose (HG) elicits a rapid upregulation of Nox4 protein via translational mechanisms. Nox4 mRNA 3' untranslated region (3'-UTR) contains numerous AU-rich elements (AREs) that are potential binding sites for the RNA-binding protein human antigen R (HuR). We show that HG promotes HuR activation/expression and that HuR is required for HG-induced Nox4 protein expression/mRNA translation, ROS generation, and subsequent MC fibrotic injury. Through a series of invitro RNA-binding assays, we demonstrate that HuR acts via binding to AREs in Nox4 3'-UTR in response to HG. The invivo relevance of these observations is confirmed by the findings that increased Nox4 is accompanied by the binding of HuR to Nox4 mRNA in kidneys from type 1 diabetic animals, and further suppressing HuR expression showed a reno-protective role in a type 1 diabetic mouse model via reducing MC injury, along with the improvement of hyperglycemia and renal function.
    CONCLUSIONS: We established for the first time that HuR-mediated translational regulation of Nox4 contributes to the pathogenesis of fibrosis of the glomerular microvascular bed. Thus therapeutic interventions affecting the interplay between Nox4 and HuR could be exploited as valuable tools in designing treatments for DKD.
    Keywords:  Diabetic nephropathy; Human antigen R protein; NADPH oxidase 4; Translational regulation
  3. Am J Physiol Lung Cell Mol Physiol. 2020 Apr 01.
    Agarwal S, Sharma H, Chen L, Dhillon NK.
      We previously demonstrated that the combined exposure of human pulmonary microvascular endothelial cells (HPMECs) to morphine and viral protein(s) results in the oxidative stress mediated induction of autophagy leading to shift in the cells from early apoptotic to apoptosis-resistant proliferative status associated with the angio-proliferative remodeling observed in pulmonary arterial hypertension (PAH). In this study, we tried to delineate the major source of HIV-1 protein Tat and morphine induced oxidative burst in HPMECs and its consequences on vascular remodeling and PAH in an in-vivo model. We observed switch from the initial increased expression of NADPH oxidase (NOX)2 in response to acute treatment of morphine and HIV-Tat to later increased expression of NOX4 on chronic treatment in the endoplasmic reticulum of HPMECs without any alterations in the mitochondria. Furthermore, NOX dependent induction of autophagy was observed to play a pivotal role in regulating the endothelial cell-survival. Our in-vivo findings showed significant increase in pulmonary vascular remodeling, right ventricular systolic pressure and Fulton index in HIV-transgenic rats on chronic administration of morphine. This was associated with increased oxidative stress in lung tissues as well as in rat pulmonary microvascular endothelial cells. Additionally, endothelial cells from morphine treated HIV-Tg rats demonstrated increased expression of NOX2 and NOX4 proteins; inhibition of which ameliorated their increased survival upon serum starvation. In conclusion, this study describes NADPH oxidases as one of the main players in the oxidative stress mediated endothelial dysfunction on the dual hit of HIV-viral protein(s) and opioids.
    Keywords:  HIV-Tat; apoptosis; opioids; oxidative stress; proliferation
  4. Diabetes. 2020 Apr 03. pii: db191130. [Epub ahead of print]
    Plecitá-Hlavatá L, Jabůrek M, Holendová B, Tauber J, Pavluch V, Berková Z, Cahová M, Schroeder K, Brandes RP, Siemen D, Ježek P.
      NADPH facilitates glucose-stimulated insulin secretion (GSIS) in pancreatic islet (PI) β-cells by an as yet unknown mechanism. We found NADPH oxidase, isoform-4 (NOX4), to be the major producer of cytosolic H2O2, essential for GSIS, while the increase in ATP/ADP alone was insufficient. The fast GSIS phase was absent in PIs from NOX4-null, β-cell-specific knockout mice (NOX4βKO) (not NOX2KO), and NOX4-silenced or catalase-overexpressing INS-1E cells. Lentiviral NOX4 overexpression or H2O2 rescued GSIS in PIs from NOX4βKO mice. NOX4 silencing suppressed Ca2+ oscillations and the patch-clamped ATP-sensitive potassium channel (KATP) opened more frequently at high glucose. Mitochondrial H2O2, decreasing upon GSIS, provided an alternative redox signaling when 2-oxo-isocaproate or fatty acid oxidation formed superoxide by electron-transport flavoprotein:Q-oxidoreductase. Unlike GSIS, this ceased with mitochondrial antioxidant SkQ1. Both NOX4KO and NOX4βKO strains exhibited impaired glucose tolerance and peripheral insulin resistance. Thus the redox signaling previously suggested to cause β-cell-self-checking - hypothetically induces insulin resistance when absent. In conclusion, ATP plus H2O2 elevations constitute an essential switch-on signal of insulin exocytosis for glucose and branched-chain oxoacids as secretagogues (partly for fatty acids). Redox signaling could be impaired by cytosolic antioxidants, hence those targeting mitochondria should be preferred for clinical applications to treat (pre)diabetes at any stage.
  5. Nat Rev Mol Cell Biol. 2020 Mar 30.
    Sies H, Jones DP.
      'Reactive oxygen species' (ROS) is an umbrella term for an array of derivatives of molecular oxygen that occur as a normal attribute of aerobic life. Elevated formation of the different ROS leads to molecular damage, denoted as 'oxidative distress'. Here we focus on ROS at physiological levels and their central role in redox signalling via different post-translational modifications, denoted as 'oxidative eustress'. Two species, hydrogen peroxide (H2O2) and the superoxide anion radical (O2·-), are key redox signalling agents generated under the control of growth factors and cytokines by more than 40 enzymes, prominently including NADPH oxidases and the mitochondrial electron transport chain. At the low physiological levels in the nanomolar range, H2O2 is the major agent signalling through specific protein targets, which engage in metabolic regulation and stress responses to support cellular adaptation to a changing environment and stress. In addition, several other reactive species are involved in redox signalling, for instance nitric oxide, hydrogen sulfide and oxidized lipids. Recent methodological advances permit the assessment of molecular interactions of specific ROS molecules with specific targets in redox signalling pathways. Accordingly, major advances have occurred in understanding the role of these oxidants in physiology and disease, including the nervous, cardiovascular and immune systems, skeletal muscle and metabolic regulation as well as ageing and cancer. In the past, unspecific elimination of ROS by use of low molecular mass antioxidant compounds was not successful in counteracting disease initiation and progression in clinical trials. However, controlling specific ROS-mediated signalling pathways by selective targeting offers a perspective for a future of more refined redox medicine. This includes enzymatic defence systems such as those controlled by the stress-response transcription factors NRF2 and nuclear factor-κB, the role of trace elements such as selenium, the use of redox drugs and the modulation of environmental factors collectively known as the exposome (for example, nutrition, lifestyle and irradiation).
  6. J Hepatol. 2020 Mar 30. pii: S0168-8278(20)30189-6. [Epub ahead of print]
    Bernsmeier C, van der Merwe S, Périanin A.
      Cirrhosis is a multi-systemic disease where inflammatory responses originating from advanced liver disease and its sequelae affect distant compartments. Patients with cirrhosis are susceptible to develop bacterial infections, which may precipitate acute decompensation (AD) and acute-on-chronic liver failure (ACLF), associated with a high short-term mortality. Innate immune cells are essential as first line of defence against pathogens due to their various rapid antibacterial activities such as the production of reactive oxygen species (ROS) via NADPH oxidases (NOX), degranulation, phagocytosis, and formation of extracellular chromatin traps. This review focuses on the continuous and distinct perturbations arising in innate immune cells during cirrhosis development including their impact on disease progression as well as potential future therapeutic targets. Activation of liver macrophages (Kupffer cells) and resident mastocytes generate proinflammatory and vaso-permeating mediators that induce accumulation of neutrophils, lymphocytes, eosinophils and monocytes into the liver, and promote tissue damage particularly through exacerbated ROS production. During cirrhosis progression, damage- and pathogen-associated molecular patterns activate immune cells and promote development of systemic inflammatory responses which may involve different tissues and compartments, and elicit progression to AD and ACLF. The antibacterial function of circulating neutrophils and monocytes is gradually and severely impaired as cirrhosis worsens involving contributions to disease progression. The mechanisms underlying impaired antimicrobial responses are complex and incompletely understood. They include a deficient expression of the antibacterial machinery key-protein effector NOX2, signalling defects (Mitogen-activated protein (MAP)-Kinases, protein kinase B (AKT), mammalian target of rapamycin [mTOR]), phospholipase C). They also include an expansion of monocytic myeloid-derived suppressor cells and distinct monocytic subsets expressing the TYRO3/AXL/MERTK (TAM) receptors AXL or MERTK during disease progression especially during acute decompensation and ACLF stages. Impaired antimicrobial responses can be reversed with potent toll-like receptor (TLR)3/7/8 agonists, or inhibitors of glutamine synthase and TAM receptors. TLR7/8 activation boosts bacterial elimination and increases survival in a rat model of cirrhosis. This raises perspectives for their use in immunocompromised patients and supports the notion that innate immune dysfunction promotes disease progression.
    Keywords:  ACLF; cirrhosis; decompensation; dendritic cell; eosinophil; immuneparesis; immunotherapy; innate lymphoid cell; macrophage; monocyte; neutrophil; toll-like receptor
  7. Cancer Manag Res. 2020 ;12 1991-2000
    Wei X, Ke J, Huang H, Zhou S, Guo A, Wang K, Zhan Y, Mai C, Ao W, Xie F, Luo R, Xiao J, Wei H, Chen B.
      Introduction: Hepatocellular carcinoma (HCC) is the fifth most common cancer in the world. Up to now, many genes associated with HCC have not yet been identified. In this study, we screened the HCC-related genes through the integrated analysis of the TCGA database, of which the potential biomarkers were also further validated by clinical specimens. The discovery of potential biomarkers for HCC provides more opportunities for diagnostic indicators or gene-targeted therapies.Methods: Cancer-related genes in The Cancer Genome Atlas (TCGA) HCC database were screened by a random forest (RF) classifier based on the RF algorithm. Proteins encoded by the candidate genes and other associated proteins obtained via protein-protein interaction (PPI) analysis were subjected to Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses. The newly identified genes were further validated in the HCC cell lines and clinical tissue specimens by Western blotting, immunofluorescence, and immunohistochemistry (IHC). Survival analysis verified the clinical value of genes.
    Results: Ten genes with the best feature importance in the RF classifier were screened as candidate genes. By comprehensive analysis of PPI, GO and KEGG, these genes were confirmed to be closely related to HCC tumors. Representative NOX4 and FLVCR1 were selected for further validation by biochemical analysis which showed upregulation in both cancer cell lines and clinical tumor tissues. High expression of NOX4 or FLVCR1 in cancer cells predicts low survival.
    Conclusion: Herein, we report that NOX4 and FLVCR1 are promising biomarkers for HCC that may be used as diagnostic indicators or therapeutic targets.
    Keywords:  FLVCR1; NOX4; TCGA database; biomarkers; hepatocellular carcinoma
  8. Cardiovasc Res. 2020 Mar 28. pii: cvaa074. [Epub ahead of print]
    Schröder K.