bims-noxint Biomed News
on NADPH oxidases in tumorigenesis
Issue of 2020‒07‒12
nine papers selected by
Laia Caja Puigsubira
Uppsala University

  1. Antioxidants (Basel). 2020 Jul 05. pii: E586. [Epub ahead of print]9(7):
    Zimnol A, Spicker N, Balhorn R, Schröder K, Schupp N.
      In higher concentrations, the blood pressure regulating hormone angiotensin II leads to vasoconstriction, hypertension, and oxidative stress by activating NADPH oxidases which are a major enzymatic source of reactive oxygen species (ROS). With the help of knockout animals, the impact of the three predominant NADPH oxidases present in the kidney, i.e., Nox1, Nox2 and Nox4 on angiotensin II-induced oxidative damage was studied. Male wildtype (WT) C57BL/6 mice, Nox1-, Nox2- and Nox4-deficient mice were equipped with osmotic minipumps, delivering either vehicle (PBS) or angiotensin II, for 28 days. Angiotensin II increased blood pressure and urinary albumin levels significantly in all treated mouse strains. In Nox1 knockout mice these increases were significantly lower than in WT, or Nox2 knockout mice. In WT mice, angiotensin II also raised systemic oxidative stress, ROS formation and DNA lesions in the kidney. A local significantly increased ROS production was also found in Nox2 and Nox4 knockout mice but not in Nox1 knockout mice who further had significantly lower systemic oxidative stress and DNA damage than WT animals. Nox2 and Nox4 knockout mice had increased basal DNA damage, concealing possible angiotensin II-induced increases. In conclusion, in the kidney, Nox1 seemed to play a role in angiotensin II-induced DNA damage.
    Keywords:  DNA damage; NADPH oxidase; hypertension; kidney function
  2. Exp Dermatol. 2020 Jul 08.
    Emmert H, Fonfara M, Rodriguez E, Weidinger S.
      Emerging evidence suggests oxidative stress plays a role in the pathophysiology of both atopic dermatitis (AD) and psoriasis (PSO). We established in vitro models of AD and PSO skin, and characterized these models in regard to their oxidative stress state. Both AD- and PSO- model keratinocytes exhibited elevated reactive oxygen species (ROS) levels and accumulated more DNA damage than control cells after oxidative stress induced by 250 µM H2 O2 . Elevated ROS levels and DNA damage accumulation could be inhibited by the NADPH oxidase (NOX) inhibitor Diphenyleneiodonium (DPI). Further, immunofluorescence analysis revealed the presence of both NOX1 and NOX4 in keratinocytes. By inhibiting NOX1, stress related signalling cascades and elevated ROS levels could be abrogated, and survival of AD and PSO cells improved. Taken together this study reveals that inhibition of NOX inhibition could abrogate elevated oxidative stress in a 2D model of AD and PSO .
    Keywords:  Atopic dermatitis (AD); Diphenyleneiodonium (DPI); NADPH Oxidase (NOX); NOX1; NOX4; Psoriasis (PSO); oxidative stress; reactive oxygen species (ROS)
  3. Cancer Cell. 2020 Jun 23. pii: S1535-6108(20)30274-9. [Epub ahead of print]
    Hayes JD, Dinkova-Kostova AT, Tew KD.
      Contingent upon concentration, reactive oxygen species (ROS) influence cancer evolution in apparently contradictory ways, either initiating/stimulating tumorigenesis and supporting transformation/proliferation of cancer cells or causing cell death. To accommodate high ROS levels, tumor cells modify sulfur-based metabolism, NADPH generation, and the activity of antioxidant transcription factors. During initiation, genetic changes enable cell survival under high ROS levels by activating antioxidant transcription factors or increasing NADPH via the pentose phosphate pathway (PPP). During progression and metastasis, tumor cells adapt to oxidative stress by increasing NADPH in various ways, including activation of AMPK, the PPP, and reductive glutamine and folate metabolism.
    Keywords:  AP-1; BACH1; FOXO; HIF-1alpha; HSF1; NADPH generation; NF-κB; NRF2; PGC-1alpha; TP53; adaptation; antioxidant; dormant cancer cell; folate metabolism; glutathione; initiation; metastasis; oxidative stress; pentose phosphate pathway; progression; reactive oxygen species; recurrent disease; redox signaling; reductive glutamine metabolism; thioredoxin; tumorigenesis
  4. J Leukoc Biol. 2020 Jul 08.
    Bechor E, Zahavi A, Berdichevsky Y, Pick E.
      Activation of the Nox2-dependent NADPH oxidase is the result of a conformational change in Nox2 induced by interaction with the cytosolic component p67phox . In preliminary work we identified a cluster of overlapping 15-mer synthetic peptides, corresponding to p67phox residues 259-279, which inhibited oxidase activity in an in vitro, cell-free assay, but the results did not point to a competitive mechanism. We recently identified an auto-inhibitory intramolecular bond in p67phox , one extremity of which was located within the 259-279 sequence, and we hypothesized that inhibition by exogenous peptides might mimic intrinsic auto-inhibition. In this study, we found that: (i) progressive N- and C-terminal truncation of inhibitory p67phox peptides, corresponding to residues 259-273 and 265-279, revealed that inhibitory ability correlated with the presence of residues 265 NIVFVL270 , exposed at either the N- or C-termini of the peptides; (ii) inhibition of oxidase activity was associated exclusively with self-assembled peptides, which pelleted upon centrifugation at 12,000 ×g; (iii) self-assembled p67phox peptides inhibited oxidase activity by specific binding of p67phox and the ensuing depletion of this component, essential for interaction with Nox2; and (iv) peptides subjected to scrambling or reversing the order of residues in NIVFVL retained the propensity for self-assembly, oxidase inhibitory ability, and specific binding of p67phox , indicating that the dominant parameter was the hydrophobic character of five of the six residues. This appears to be the first description of inhibition of oxidase activity by self-assembled peptides derived from an oxidase component, acting by an auto-inhibitory mechanism.
    Keywords:  NADPH oxidase; cell-free assay; intramolecular bond; protein- peptide interaction; synthetic peptides
  5. Cancers (Basel). 2020 Jul 07. pii: E1822. [Epub ahead of print]12(7):
    Hyun DH.
      Modest levels of reactive oxygen species (ROS) are necessary for intracellular signaling, cell division, and enzyme activation. These ROS are later eliminated by the body's antioxidant defense system. High amounts of ROS cause carcinogenesis by altering the signaling pathways associated with metabolism, proliferation, metastasis, and cell survival. Cancer cells exhibit enhanced ATP production and high ROS levels, which allow them to maintain elevated proliferation through metabolic reprograming. In order to prevent further ROS generation, cancer cells rely on more glycolysis to produce ATP and on the pentose phosphate pathway to provide NADPH. Pro-oxidant therapy can induce more ROS generation beyond the physiologic thresholds in cancer cells. Alternatively, antioxidant therapy can protect normal cells by activating cell survival signaling cascades, such as the nuclear factor erythroid 2-related factor 2 (Nrf2)-Kelch-like ECH-associated protein 1 (Keap1) pathway, in response to radio- and chemotherapeutic drugs. Nrf2 is a key regulator that protects cells from oxidative stress. Under normal conditions, Nrf2 is tightly bound to Keap1 and is ubiquitinated and degraded by the proteasome. However, under oxidative stress, or when treated with Nrf2 activators, Nrf2 is liberated from the Nrf2-Keap1 complex, translocated into the nucleus, and bound to the antioxidant response element in association with other factors. This cascade results in the expression of detoxifying enzymes, including NADH-quinone oxidoreductase 1 (NQO1) and heme oxygenase 1. NQO1 and cytochrome b5 reductase can neutralize ROS in the plasma membrane and induce a high NAD+/NADH ratio, which then activates SIRT1 and mitochondrial bioenergetics. NQO1 can also stabilize the tumor suppressor p53. Given their roles in cancer pathogenesis, redox homeostasis and the metabolic shift from glycolysis to oxidative phosphorylation (through activation of Nrf2 and NQO1) seem to be good targets for cancer therapy. Therefore, Nrf2 modulation and NQO1 stimulation could be important therapeutic targets for cancer prevention and treatment.
    Keywords:  NQO1; Nrf2-Keap1; cancer; glycolysis; oxidative phosphorylation; oxidative stress
  6. Theranostics. 2020 ;10(16): 7083-7099
    Shen CJ, Chang KY, Lin BW, Lin WT, Su CM, Tsai JP, Liao YH, Hung LY, Chang WC, Chen BK.
      Background: Colorectal cancer (CRC) progression and related mortality are highly associated with metabolic disorders. However, the molecular mechanism involved in the regulation of hyperlipidemia-associated CRC metastasis remains unclear. This study aimed to investigate the effects of angiopoietin-like 4 (ANGPTL4) on NADPH oxidase 4 (NOX4) expression and reactive oxygen species (ROS) production, which might provide new targets for improving outcomes in patients with hyperlipidemia-associated CRC metastasis. Methods: The clinical relevance of relationship between NOX4 expression and ANGPTL4 was examined in CRC patients by the Oncomine and TCGA data set. Expressions of NOX4, epithelial-mesenchymal transition (EMT) markers, and gene regulation of NOX4 in free fatty acids (FFAs)-treated CRC cells were determined. The FFAs-triggered metastatic ability of CRC cells under treatments of antioxidants or knockdown of NOX4, ANGPTL4, and MMPs was evaluated in vitro and in vivo. In addition, effects of antioxidants and depletion of metastasis-associated molecules on the correlation between ROS production and FFAs-promoted CRC metastasis were also clarified. Results: In this study, we found that the induction of NOX4, followed by the increased ROS was essential for oleic acid (OA)-promoted CRC cell metastasis. The depletion of ANGPTL4 significantly inhibited c-Jun-mediated transactivation of NOX4 expression, accompanied with reduced levels of ROS, MMP-1, and MMP-9, resulting in the disruption of OA-promoted CRC cell metastasis. Moreover, knockdown of ANGPTL4, NOX4, MMP-1, and MMP-9 or the treatment of antioxidants dramatically inhibited circulating OA-enhanced tumor cell extravasation and metastatic seeding of tumor cells in lungs, indicating that the ANGPTL4/NOX4 axis was critical for dyslipidemia-associated tumor metastasis. Conclusion: The coincident expression of NOX4 and ANGPTL4 in CRC tumor specimens provides the insight into the potential therapeutic targets for the treatment of dyslipidemia-associated CRC metastasis.
    Keywords:  ANGPTL4; NOX4; colorectal cancer; metastasis; oleic acid
  7. Front Cell Dev Biol. 2020 ;8 513
    Wang Q, Wei S, Zhou H, Li L, Zhou S, Shi C, Shi Y, Qiu J, Lu L.
      Liver fibrosis is a major endpoint of patients with chronic liver diseases. The molecular mechanisms behind liver fibrosis remain largely unknown. Many studies have indicated the role of microRNA (miRNA) in hepatic tumorigenesis. But the role of miRNA in liver fibrosis is little known. Activated hepatic stellate cells (HSCs) can secret extracellular matrix proteins (ECM) and are the major contributors to liver fibrosis/cirrhosis. Here, a microarray assay of quiescent and transforming growth factor β1 (TGF-β1) activated HSCs indicated that miR-98 might play a crucial role in liver fibrosis. We found that miR-98 was significantly downregulated in activated HSCs. miR-98 overexpression inhibited HSCs activation. Furthermore, we hypothesized that miR-98 regulated hepatic leukemia factor (HLF) expression by binding to the 3' UTR of its mRNA directly, as evidenced by luciferase reporter assay. HLF overexpression increased HSCs activation by inducing hypoxia inducible factor-1 alpha (HIF-1α) expression, resulting in the activation of TGF-β/Smad2/3 signaling pathway. Besides, low expression of miR-98 was also found in liver tissues from various fibrotic murine models, including carbon tetrachloride (CCl4), bile duct ligation (BDL), and high-fat diet (HFD)-induced liver fibrosis. miR-98 overexpression in vivo by ago-miR-98 injection could attenuate CCl4-, BDL-, and HFD-induced murine hepatic fibrosis. Meanwhile, miR-98 overexpression suppressed HLF expression and reduced fibrosis marker expression. Collectively, our study demonstrates that miR-98 suppress HSCs activation by targeting HLF directly and interacting with HIF-1α/TGF-β/Smad2/3 signaling pathway, which may be an effective therapeutic target for liver fibrosis.
    Keywords:  HIF-1α; HLF; hepatic stellate cell; liver fibrosis; microRNA-98
  8. J Biol Chem. 2020 Jul 07. pii: jbc.RA120.012915. [Epub ahead of print]
    Arrington ME, Temple B, Schaefer A, Campbell SL.
      The RAS-related C3 botulinum toxin substrate 2 (RAC2) is a member of the RHO sub-class of RAS superfamily GTPases required for proper immune function.  An activating mutation in a key switch II region of RAC2 (RAC2E62K) involved in recognizing modulatory factors and effectors has been identified in patients with common variable immune deficiency (CVID).  To better understand how the mutation dysregulates RAC2 function, we evaluated the structure and stability, GEF and GAP activity, and effector binding of RAC2E62K  Our findings indicate the E62K mutation does not alter RAC2 structure or stability.  However, it does alter GEF specificity, as RAC2E62K is activated by the DOCK GEF, DOCK2, but not by the Dbl Homology GEF, TIAM1, both of which activate the parent protein.  Our previous data further showed that the E62K mutation impairs GAP activity for RAC2E62K  As this disease mutation is also found in RAS GTPases, we assessed GAP-stimulated GTP hydrolysis for KRAS and observed a similar impairment, suggesting the mutation plays a conserved role in GAP activation.  We also investigated whether the E62K mutation alters effector binding, as activated RAC2 binds effectors to transmit signaling through effector pathways. We find RAC2E62K retains binding to an NADPH oxidase (NOX2) subunit, p67phox, and to the RAC binding domain of p21-activated kinase (PAK), consistent with our earlier findings. Taken together, our findings indicate that the RAC2E62K mutation promotes immune dysfunction by promoting RAC2 hyper-activation, altering GEF specificity, and impairing GAP function yet retaining key effector interactions.
    Keywords:  Dedicator of cytokinesis (DOCK); GTPase activating protein (GAP); NADPH oxidase; Ras protein; Ras-related C3 botulinum toxin substrate 2 (RAC2); T-cell lymphoma and metastasis 1 (TIAM1); guanine nucleotide exchange factor (GEF); immunodeficiency; molecular dynamics; serine/threonine-protein kinase PAK 1 (PAK1)
  9. J Neuroinflammation. 2020 Jul 04. 17(1): 201
    Mondal A, Bose D, Saha P, Sarkar S, Seth R, Kimono D, Albadrani M, Nagarkatti M, Nagarkatti P, Chatterjee S.
      BACKGROUND: Recent clinical and basic research implicated a strong correlation between NAFLD/NASH phenotypes with ectopic manifestations including neuroinflammation and neurodegeneration, but the mediators and critical pathways involved are not well understood. Lipocalin 2 (Lcn2) is one of the important mediators exclusively produced in the liver and circulation during NASH pathology.METHODS: Using murine model of NASH, we studied the role of Lcn2 as a potent mediator of neuroinflammation and neurodegeneration in NASH pathology via the liver-brain axis.
    RESULTS: Results showed that high circulatory Lcn2 activated 24p3R (Lipocalin2 receptor) in the brain and induced the release of high mobility group box 1 (HMGB1) preferably from brain cells. Released HMGB1 acted as a preferential ligand to toll-like receptor 4 (TLR4) and induced oxidative stress by activation of NOX-2 signaling involving activated p65 protein of the NF-κB complex. Further, the HMGB1-derived downstream signaling cascade activated NLRP3 inflammasome and release of proinflammatory cytokines IL-6 and IL-1β from brain cells. In addition, to advance our present understanding, in vitro studies were performed in primary brain endothelial cells where results showed high circulatory Lcn2 influenced HMGB1 secretion. Mechanistically, we also showed that elevated Lcn2 level in underlying NASH might be a likely cause for induction of blood-brain barrier dysfunction since the adipokine decreased the expression of tight junction protein Claudin 5 and caused subsequent elevation of pro-inflammatory cytokines IL-6 and IL-1β.
    CONCLUSION: In conclusion, the NASH-induced brain pathology might be because of increased Lcn2-induced release of HMGB1 and accompanying neuroinflammation.
    Keywords:  Lcn-2; MCD; NASH; NLRP3; NOX-2; Redox signaling; TLR4