bims-noxint Biomed News
on NADPH oxidases in tumorigenesis
Issue of 2020‒09‒27
eight papers selected by
Laia Caja Puigsubira
Uppsala University

  1. Redox Biol. 2020 Sep 04. pii: S2213-2317(20)30918-6. [Epub ahead of print]37 101713
      OBJECTIVE: Oxidative stress is a risk factor for atherosclerosis. NADPH oxidases of the Nox family produce ROS but their contribution to atherosclerosis development is less clear. Nox2 promotes and Nox4 rather limits atherosclerosis. Although Nox1 with its cytosolic co-factors are largely expressed in epithelial cells, a role for Nox1 for atherosclerosis development was suggested. To further define the role of this homologue, the role of its essential cytosolic cofactor, NoxO1, was determined for atherosclerosis development with the aid of knockout mice.METHODS AND RESULTS: Wildtype (WT) and NoxO1 knockout mice were treated with high fat diet and adeno-associated virus (AAV) overexpressing pro-protein convertase subtilisin/kexin type 9 (PCSK9) to induce hepatic low-density lipoprotein (LDL) receptor loss. As a result, massive hypercholesterolemia was induced and spontaneous atherosclerosis developed within three month. Deletion of NoxO1 reduced atherosclerosis formation in brachiocephalic artery and aortic arch in female but not male NoxO1-/- mice as compared to WT littermates. This was associated with a reduced pro-inflammatory cytokine signature in the plasma of female but not male NoxO1-/- mice. MACE-RNAseq of the vessel did not reveal this signature and the expression of the Nox1/NoxO1 system was low to not detectable.
    CONCLUSIONS: The scaffolding protein NoxO1 plays some role in atherosclerosis development in female mice probably by attenuating the global inflammatory burden.
    Keywords:  Atherosclerosis; Gender differences; NADPH oxidase; NoxO1; PCSK9; Reactive oxygen species
  2. Int J Mol Sci. 2020 Sep 21. pii: E6911. [Epub ahead of print]21(18):
      The protective effects of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) 1 inhibition against kidney ischemia-reperfusion injury (IRI) remain uncertain. The bilateral kidney pedicles of C57BL/6 mice were clamped for 30 min to induce IRI. Madin-Darby Canine Kidney (MDCK) cells were incubated with H2O2 (1.4 mM) for 1 h to induce oxidative stress. ML171, a selective NOX1 inhibitor, and siRNA against NOX1 were treated to inhibit NOX1. NOX expression, oxidative stress, apoptosis assay, and mitogen-activated protein kinase (MAPK) pathway were evaluated. The kidney function deteriorated and the production of reactive oxygen species (ROS), including intracellular H2O2 production, increased due to IRI, whereas IRI-mediated kidney dysfunction and ROS generation were significantly attenuated by ML171. H2O2 evoked the changes in oxidative stress enzymes such as SOD2 and GPX in MDCK cells, which was mitigated by ML171. Treatment with ML171 and transfection with siRNA against NOX1 decreased the upregulation of NOX1 and NOX4 induced by H2O2 in MDCK cells. ML171 decreased caspase-3 activity, the Bcl-2/Bax ratio, and TUNEL-positive tubule cells in IRI mice and H2O2-treated MDCK cells. Among the MAPK pathways, ML171 affected ERK signaling by ERK phosphorylation in kidney tissues and tubular cells. NOX1-selective inhibition attenuated kidney IRI via inhibition of ROS-mediated ERK signaling.
    Keywords:  ERK; ML171; NOX1; acute kidney injury; ischemia-reperfusion injury; reactive oxygen species
  3. Cell Biochem Funct. 2020 Sep 25.
      Reactive oxygen species (ROS), formed by the partial reduction of oxygen, were for a long time considered to be a byproduct of cellular metabolism. Since, increase in cellular levels of ROS results in oxidative stress leading to damage of nucleic acids, proteins, and lipids resulting in numerous pathological conditions; ROS was considered a bane for aerobic species. Hence, the discovery of NADPH oxidases (NOX), an enzyme family that specifically generates ROS as its prime product came as a surprise to redox biologists. NOX family proteins participate in various cellular functions including cell proliferation and differentiation, regulation of genes and protein expression, apoptosis, and host defence immunological response. Balanced expression and activation of NOX with subsequent production of ROS are critically important to regulate various genes and proteins to maintain homeostasis of the cell. However, dysregulation of NOX activation leading to enhanced ROS levels is associated with various pathophysiologies including diabetes, cardiovascular diseases, neurodegenerative diseases, ageing, atherosclerosis, and cancer. Although our current knowledge on NOX signifies its importance in the normal functioning of various cellular pathways; yet the choice of ROS producing enzymes which can tip the scale from homeostasis toward damage, as mediators of biological functions remain an oddity. Though the role of NOX in maintaining normal cellular functions is now deemed essential, yet its dysregulation leading to catastrophic events cannot be denied. Hence, this review focuses on the involvement of NOX enzymes in various pathological conditions imploring them as possible targets for therapies. SIGNIFICANCE OF THE STUDY: The NOXs are multi-subunit enzymes that generate ROS as a prime product. NOX generated ROS are usually regulated by various molecular factors and play a vital role in different physiological processes. The dysregulation of NOX activity is associated with pathological consequences. Recently, the dynamic proximity of NOX enzymes with different molecular signatures of pathologies has been studied extensively. It is essential to identify the precise role of NOX machinery in its niche during the progression of pathology. Although inhibition of NOX could be a promising approach for therapeutic interventions, it is critical to expand the current understanding of NOX's dynamicity and shed light on their molecular partners and regulators.
    Keywords:  Cancer; Inflammation; NADPH oxidase; Oxidative stress; Reactive oxygen species
  4. Redox Biol. 2020 Sep 14. pii: S2213-2317(20)30927-7. [Epub ahead of print]37 101722
      Understanding how mitochondria contribute to cellular oxidative stress and drive signaling and disease is critical, but quantitative assessment is difficult. Our previous studies of cultured C2C12 cells used inhibitors of specific sites of superoxide and hydrogen peroxide production to show that mitochondria generate about half of the hydrogen peroxide released by the cells, and site IQ of respiratory complex I produces up to two thirds of the superoxide and hydrogen peroxide generated in the mitochondrial matrix. Here, we used the same approach to measure the engagement of these sites in seven diverse cell lines to determine whether this pattern is specific to C2C12 cells, or more general. These diverse cell lines covered primary, immortalized, and cancerous cells, from seven tissues (liver, cervix, lung, skin, neuron, heart, bone) of three species (human, rat, mouse). The rate of appearance of hydrogen peroxide in the extracellular medium spanned a 30-fold range from HeLa cancer cells (3 pmol/min/mg protein) to AML12 liver cells (84 pmol/min/mg protein). The mean contribution of identified mitochondrial sites to this extracellular hydrogen peroxide signal was 30 ± 7% SD; the mean contribution of NADPH oxidases was 60 ± 14%. The relative contributions of different sites in the mitochondrial electron transport chain were broadly similar in all seven cell types (and similar to published results for C2C12 cells). 70 ± 4% of identified superoxide/hydrogen peroxide generation in the mitochondrial matrix was from site IQ; 30 ± 4% was from site IIIQo. We conclude that although absolute rates vary considerably, the relative contributions of different sources of hydrogen peroxide production are similar in nine diverse cell types under unstressed conditions in vitro. Identified mitochondrial sites account for one third of total cellular hydrogen peroxide production (half each from sites IQ and IIIQo); in the mitochondrial matrix the majority (two thirds) of superoxide/hydrogen peroxide is from site IQ.
    Keywords:  Hydrogen peroxide; Matrix; Mitochondria; NOX; S1QEL; S3QEL; Superoxide
  5. Cancer Immunol Res. 2020 Sep 23. pii: canimm.0055.2020. [Epub ahead of print]
      The phosphatidylinositol-4,5-bisphosphate-3 kinase-δ (PI3Kδ) inhibitor idelalisib, used alone or in combination with anti-CD20, is clinically efficacious in B cell lymphoma and chronic lymphocytic leukemia (CLL) by promoting apoptosis of malignant B cells. PI3K regulates the formation of reactive oxygen species (ROS) by the myeloid NADPH oxidase NOX2, but the role of PI3Kδ in myeloid cell-induced immunosuppression is unexplored. We assessed the effects of idelalisib on the spontaneous and IgG antibody-induced ROS production by human monocytes, on ROS-induced cell death of human NK cells, and on tumor cell clearance in an NK cell-dependent mouse model of metastasis. Idelalisib potently and efficiently inhibited the formation of NOX2-derived ROS from monocytes and rescued NK cells from ROS-induced cell death. Idelalisib also promoted NK cell cytotoxicity against anti-CD20-coated primary human CLL cells and cultured malignant B cells. Experiments using multiple PI3K inhibitors implicated the PI3Kδ isoform in regulating NOX2-induced ROS formation and immunosuppression. In B6 mice, systemic treatment with idelalisib significantly reduced the formation of lung metastases from intravenously injected melanoma cells but did not affect metastasis in B6.129S6-Cybbtm1Din (Nox2-/-) mice or in NK cell-deficient mice. Our results imply that idelalisib rescues NK cells from NOX2/ROS-dependent immunosuppression and thus exerts anti-neoplastic efficacy beyond B cell inhibition.
  6. Int J Biochem Cell Biol. 2020 Sep 16. pii: S1357-2725(20)30168-0. [Epub ahead of print] 105851
      Oxidative stress is one of the main mechanisms involved in the pathophysiology of vascular diseases. Among others, oxidative stress promotes endothelial dysfunction, and accelerated ageing and remodelling of vasculature. Lately, NADPH oxidases have been demonstrated to be involved in cardiovascular diseases. NADPH oxidase 5 has emerged as a new player in oxidative stress-mediated endothelial alterations, involved in the pathophysiology of hypertension, diabetes, atherosclerosis, myocardial infarction and stroke. This oxidase seems to mediate its detrimental effects by promoting inflammation. NADPH oxidase 5 has been studied in a lesser extent compared with the other members of the NADPH oxidase family due to its loss in the rodent genome, the main experimental research model. In addition, its potential as a therapeutic target remains unexplored given the lack of specific inhibitors. In this review the latest findings on NADPH oxidase 5 regulation, implications in vascular pathophysiology and therapeutic approaches will be updated.
    Keywords:  Endothelial dysfunction; Inflammation; NADPH oxidase 5; Oxidative stress; Vascular diseases
  7. Hepatology. 2020 Sep 07.
      BACKGROUND & AIMS: Apelin is the endogenous ligand of its G-protein coupled receptor, APJ. Apelin serum levels are increased in human liver diseases. We evaluated whether apelin-APJ regulates ductular reaction and liver fibrosis during cholestasis.APPROACH & RESULTS: We measured the expression of apelin and APJ, and serum apelin levels in human primary sclerosing cholangitis (PSC) samples. Following bile duct ligation (BDL) or sham surgery, male wild-type mice were treated with ML221 (APJ antagonist) or saline for 1 wk. WT and apelin-/- mice underwent BDL or sham for 1 week. Mdr2-/- mice were treated with ML221 for 1 wk. Apelin levels were measured in serum and cholangiocyte supernatants, and cholangiocyte proliferation/senescence and liver inflammation, fibrosis and angiogenesis were measured in liver tissues. The regulatory mechanisms of apelin-APJ in: (i) biliary damage and liver fibrosis were examined in human biliary cells (HIBEpiCs) treated with apelin; and (ii) HSC activation in apelin-treated human hepatic stellate cell lines (HHSteCs). Apelin serum levels and biliary expression of apelin and APJ increased in PSC samples. Apelin levels were higher in serum and cholangiocyte supernatants from BDL and Mdr2-/- mice. ML221 treatment or apelin-/- reduced BDL- and Mdr2-/--induced cholangiocyte proliferation/senescence, liver inflammation, fibrosis and angiogenesis. In vitro, apelin induced HIBEpiC proliferation, Nox4 expression, ROS generation and ERK phosphorylation. Pretreatment of HIBEpiCs with ML221, DPI (Nox4 inhibitor), NAC (ROS inhibitor) or PD98059 (ERK inhibitor) reduced apelin-induced cholangiocyte proliferation. Activation of HHSteCs was induced by apelin, but reduced by NAC.
    CONCLUSIONS: Apelin-APJ axis induces cholangiocyte proliferation via Nox4/ROS/ERK dependent signaling and induces HSC activation via intracellular ROS. Modulation of the apelin-APJ axis may be important for managing cholangiopathies.
    Keywords:  Angiogenesis; biliary damage; cellular senescence; ductular reaction; reactive oxygen species
  8. J Clin Invest. 2020 Sep 22. pii: 136042. [Epub ahead of print]
      The aorta and the large conductive arteries are immunoprivileged tissues and are protected against inflammatory attack. A breakdown of the immunoprivilege leads to autoimmune vasculitis, such as giant cell arteritis (GCA), in which CD8+ T regulatory (Treg) cells fail to contain CD4+ T cells and macrophages, resulting in the formation of tissue-destructive granulomatous lesions. Here, we report that the molecular defect of malfunctioning CD8+ Treg cells lies in aberrant NOTCH4 signaling that deviates endosomal trafficking and minimizes exosome production. By transcriptionally controlling the profile of RAB GTPases, NOTCH4 signaling restricted membrane translocation and vesicular secretion of the enzyme NADPH oxidase 2 (NOX2). Specifically, NOTCH4hiCD8+ Treg cells increased RAB5A and RAB11A expression and suppressed RAB7A, culminating in the accumulation of early and recycling endosomes and trapping of NOX2 in an intracellular, non-secretory compartment. RAB7AloCD8+ Treg cells failed in the surface translocation and the exosomal release of NOX2. NOTCH4hi RAB5Ahi RAB7Alo RAB11Ahi CD8+ Treg cells left adaptive immunity unopposed, enabling a breakdown in tissue tolerance and aggressive vessel wall inflammation. Inhibiting NOTCH4 signaling corrected the defect and protected arteries from inflammatory insult. The study implicates NOTCH4-dependent transcriptional control of RAB proteins and intracellular vesicle trafficking in autoimmune disease and in vascular inflammation.
    Keywords:  Adaptive immunity; Autoimmunity; Immunology; T cells; Vasculitis