bims-noxint 2019-05-19 papers

bims-noxint

Biomed News

on NADPH oxidases in tumorigenesis

Issue of 2019–05–19
seven papers selected by
Laia Caja Puigsubira, Uppsala University

H2O2 Metabolism in Normal Thyroid Cells and in Thyroid Tumorigenesis: Focus on NADPH Oxidases.
Inositol-triphosphate 3-kinase B confers cisplatin resistance by regulating NOX4-dependent redox balance.
Myc-mediated transcriptional regulation of the mitochondrial chaperone TRAP1 controls primary and metastatic tumor growth.
Rac-GTPase promotes fibrotic TGF-β1 signaling and chronic kidney disease via EGFR, p53, and Hippo/YAP/TAZ pathways.
TrxR1, Gsr, and oxidative stress determine hepatocellular carcinoma malignancy.
A RASSF1A-HIF1α loop drives Warburg effect in cancer and pulmonary hypertension.
UCP2 regulates cholangiocarcinoma cell plasticity via mitochondria-to-AMPK signals.

Antioxidants (Basel). 2019 May 10. pii: E126. [Epub ahead of print]8(5):

H2O2 Metabolism in Normal Thyroid Cells and in Thyroid Tumorigenesis: Focus on NADPH Oxidases.

Ildiko Szanto, Marc Pusztaszeri, Maria Mavromati.

  Thyroid hormone synthesis requires adequate hydrogen peroxide (H2O2) production that is utilized as an oxidative agent during the synthesis of thyroxin (T4) and triiodothyronine (T3). Thyroid H2O2 is generated by a member of the family of NADPH oxidase enzymes (NOX-es), termed dual oxidase 2 (DUOX2). NOX/DUOX enzymes produce reactive oxygen species (ROS) as their unique enzymatic activity in a timely and spatially regulated manner and therefore, are important regulators of diverse physiological processes. By contrast, dysfunctional NOX/DUOX-derived ROS production is associated with pathological conditions. Inappropriate DUOX2-generated H2O2 production results in thyroid hypofunction in rodent models. Recent studies also indicate that ROS improperly released by NOX4, another member of the NOX family, are involved in thyroid carcinogenesis. This review focuses on the current knowledge concerning the redox regulation of thyroid hormonogenesis and cancer development with a specific emphasis on the NOX and DUOX enzymes in these processes.

Keywords:  DUOX2; NADPH oxidase; NOX4; Thyroid; dual oxidase; redox

DOI:  https://doi.org/10.3390/antiox8050126
J Clin Invest. 2019 May 13. pii: 124550. [Epub ahead of print]130

Inositol-triphosphate 3-kinase B confers cisplatin resistance by regulating NOX4-dependent redox balance.

Chaoyun Pan, Lingtao Jin, Xu Wang, Yuancheng Li, Jaemoo Chun, Austin C Boese, Dan Li, Hee-Bum Kang, Guojing Zhang, Lu Zhou, Georgia Z Chen, Nabil F Saba, Dong M Shin, Kelly R Magliocca, Taofeek K Owonikoko, Hui Mao, Sagar Lonial, Sumin Kang.

  How altered metabolism contributes to chemotherapy resistance in cancer cells remains unclear. Through a metabolism-related kinome RNAi screen, we identified inositol-trisphosphate 3-kinase B (ITPKB) as a critical enzyme that contributes to cisplatin-resistant tumor growth. We demonstrated that inositol 1,3,4,5-tetrakisphosphate (IP4), the product of ITPKB, plays a critical role in redox homeostasis upon cisplatin exposure by reducing cisplatin-induced ROS through inhibition of a ROS-generating enzyme, NADPH oxidase 4 (NOX4), which promotes cisplatin-resistant tumor growth. Mechanistically, we identified that IP4 competes with the NOX4 cofactor NADPH for binding and consequently inhibits NOX4. Targeting ITPKB with shRNA or its small-molecule inhibitor resulted in attenuation of NOX4 activity, imbalanced redox status, and sensitized cancer cells to cisplatin treatment in patient-derived xenografts. Our findings provide insight into the crosstalk between kinase-mediated metabolic regulation and platinum-based chemotherapy resistance in human cancers. Our study also suggests a distinctive signaling function of IP4 that regulates NOX4. Furthermore, pharmaceutical inhibition of ITPKB displayed synergistic attenuation of tumor growth with cisplatin, suggesting ITPKB as a promising synthetic lethal target for cancer therapeutic intervention to overcome cisplatin resistance.

Keywords:  Cancer; Cell Biology; Metabolism; Molecular biology; Signal transduction

DOI:  https://doi.org/10.1172/JCI124550
J Biol Chem. 2019 May 16. pii: jbc.AC119.008656. [Epub ahead of print]

Myc-mediated transcriptional regulation of the mitochondrial chaperone TRAP1 controls primary and metastatic tumor growth.

Ekta Agarwal, Brian J Altman, Jae Ho Seo, Jagadish C Ghosh, Andrew V Kossenkov, Hsin-Yao Tang, Shiv Ram Krishn, Lucia R Languino, Dmitry I Gabrilovich, David W Speicher, Chi V Dang, Dario C Altieri.

  The role of mitochondria in cancer continues to be debated, and whether exploitation of mitochondrial functions is a general hallmark of malignancy or a tumor- or context-specific response is still unknown. Using a variety of cancer cell lines and several technical approaches, including siRNA-mediated gene silencing, ChIP assays, global metabolomics and focused metabolite analyses, and bioenergetics, and cell viability assays, we show that two oncogenic Myc proteins, c-Myc and N-Myc, transcriptionally control the expression of the mitochondrial chaperone TNFR-associated protein-1 (TRAP1) in cancer. In turn, this Myc-mediated regulation preserved the folding and function of mitochondrial oxidative phosphorylation (OXPHOS) complex II and IV subunits, dampened reactive oxygen species (ROS) production and enabled oxidative bioenergetics in tumor cells. Of note, we found that genetic or pharmacological targeting of this pathway shuts off tumor cell motility and invasion, kills Myc-expressing cells in a TRAP1-dependent manner, and suppresses primary and metastatic tumor growth in vivo. We conclude that exploitation of mitochondrial functions is a general trait of tumorigenesis and that this reliance of cancer cells on mitochondrial OXPHOS pathways could offer an actionable therapeutic target in the clinic.

Keywords:  Myc (c-Myc); TRAP1; invasion; metabolism; metastasis; mitochondria; oxidative phosphorylation

DOI:  https://doi.org/10.1074/jbc.AC119.008656
FASEB J. 2019 May 16. fj201802489RR

Rac-GTPase promotes fibrotic TGF-β1 signaling and chronic kidney disease via EGFR, p53, and Hippo/YAP/TAZ pathways.

Samik Patel, Jiaqi Tang, Jessica M Overstreet, Sandybell Anorga, Fei Lian, Alex Arnouk, Roel Goldschmeding, Paul J Higgins, Rohan Samarakoon.

  Rac-GTPases are major regulators of cytoskeletal remodeling and their deregulation contributes to numerous pathologies. Whether or how Rac promotes tubulointerstitial fibrosis and chronic kidney disease (CKD) is currently unknown. We showed that the major profibrotic cytokine, TGF-β1 promoted rapid Rac1-GTP loading in human kidney 2 (HK-2) human renal epithelial cells. A Rac-specific chemical inhibitor, EHT 1864, blocked TGF-β1-induced fibrotic reprogramming in kidney epithelial cells and fibroblasts. Stable Rac1 depletion in HK-2 cells, moreover, eliminated TGF-β1-mediated non-SMAD pathway activation [e.g., Src, epidermal growth factor receptor (EGFR), p53] and subsequent plasminogen activator inhibitor-1 (PAI-1), connective tissue growth factor, fibronectin, and p21 induction. Rac1 and p22phox knockdown abrogated free radical generation by TGF-β1 in HK-2 cells, consistent with the role of Rac1 in Nicotinamide adenine dinucleotide phosphate oxidase signaling. TGF-β1-induced renal epithelial cytostasis was also completely bypassed by Rac1, p22phox, p47phox, and PAI-1 silencing. Rac1b isoform expression was robustly induced in the fibrotic kidneys of mice and humans. Intraperitoneal administration of EHT 1864 in mice dramatically attenuated ureteral unilateral obstruction-driven EGFR, p53, Rac1b, yes-associated protein/transcriptional coactivator with PDZ-binding motif activation/expression, dedifferentiation, cell cycle arrest, and renal fibrogenesis evident in vehicle-treated obstructed kidneys. Thus, the Rac1-directed redox response is critical for TGF-β1-driven epithelial dysfunction orchestrated, in part, via PAI-1 up-regulation. Rac pathway inhibition suppressed renal oxidative stress and maladaptive repair, identifying Rac as a novel therapeutic target against progressive CKD.-Patel, S., Tang, J., Overstreet, J. M., Anorga, S., Lian, F., Arnouk, A., Goldschmeding, R., Higgins, P. J., Samarakoon, R. Rac-GTPase promotes fibrotic TGF-β1 signaling and chronic kidney disease via EGFR, p53, and Hippo/YAP/TAZ pathways.

Keywords:  CTGF; NADPH Oxidases; PAI-1; Rac1; renal fibrosis

DOI:  https://doi.org/10.1096/fj.201802489RR
Proc Natl Acad Sci U S A. 2019 May 16. pii: 201903244. [Epub ahead of print]

TrxR1, Gsr, and oxidative stress determine hepatocellular carcinoma malignancy.

Michael R McLoughlin, David J Orlicky, Justin R Prigge, Pushya Krishna, Emily A Talago, Ian R Cavigli, Sofi Eriksson, Colin G Miller, Jean A Kundert, Volkan I Sayin, Rachel A Sabol, Joshua Heinemann, Luke O Brandenberger, Sonya V Iverson, Brian Bothner, Thales Papagiannakopoulos, Colin T Shearn, Elias S J Arnér, Edward E Schmidt.

  Thioredoxin reductase-1 (TrxR1)-, glutathione reductase (Gsr)-, and Nrf2 transcription factor-driven antioxidant systems form an integrated network that combats potentially carcinogenic oxidative damage yet also protects cancer cells from oxidative death. Here we show that although unchallenged wild-type (WT), TrxR1-null, or Gsr-null mouse livers exhibited similarly low DNA damage indices, these were 100-fold higher in unchallenged TrxR1/Gsr-double-null livers. Notwithstanding, spontaneous cancer rates remained surprisingly low in TrxR1/Gsr-null livers. All genotypes, including TrxR1/Gsr-null, were susceptible to N-diethylnitrosamine (DEN)-induced liver cancer, indicating that loss of these antioxidant systems did not prevent cancer cell survival. Interestingly, however, following DEN treatment, TrxR1-null livers developed threefold fewer tumors compared with WT livers. Disruption of TrxR1 in a marked subset of DEN-initiated cancer cells had no effect on their subsequent contributions to tumors, suggesting that TrxR1-disruption does not affect cancer progression under normal care, but does decrease the frequency of DEN-induced cancer initiation. Consistent with this idea, TrxR1-null livers showed altered basal and DEN-exposed metabolomic profiles compared with WT livers. To examine how oxidative stress influenced cancer progression, we compared DEN-induced cancer malignancy under chronically low oxidative stress (TrxR1-null, standard care) vs. elevated oxidative stress (TrxR1/Gsr-null livers, standard care or phenobarbital-exposed TrxR1-null livers). In both cases, elevated oxidative stress was correlated with significantly increased malignancy. Finally, although TrxR1-null and TrxR1/Gsr-null livers showed strong Nrf2 activity in noncancerous hepatocytes, there was no correlation between malignancy and Nrf2 expression within tumors across genotypes. We conclude that TrxR1, Gsr, Nrf2, and oxidative stress are major determinants of liver cancer but in a complex, context-dependent manner.

Keywords:  Nrf2; glutathione reductase; hepatocellular carcinoma; oxidative stress; thioredoxin reductase

DOI:  https://doi.org/10.1073/pnas.1903244116
Nat Commun. 2019 05 13. 10(1): 2130

A RASSF1A-HIF1α loop drives Warburg effect in cancer and pulmonary hypertension.

Swati Dabral, Christian Muecke, Chanil Valasarajan, Mario Schmoranzer, Astrid Wietelmann, Gregg L Semenza, Michael Meister, Thomas Muley, Tamina Seeger-Nukpezah, Christos Samakovlis, Norbert Weissmann, Friedrich Grimminger, Werner Seeger, Rajkumar Savai, Soni S Pullamsetti.

Hypoxia signaling plays a major role in non-malignant and malignant hyperproliferative diseases. Pulmonary hypertension (PH), a hypoxia-driven vascular disease, is characterized by a glycolytic switch similar to the Warburg effect in cancer. Ras association domain family 1A (RASSF1A) is a scaffold protein that acts as a tumour suppressor. Here we show that hypoxia promotes stabilization of RASSF1A through NOX-1- and protein kinase C- dependent phosphorylation. In parallel, hypoxia inducible factor-1 α (HIF-1α) activates RASSF1A transcription via HIF-binding sites in the RASSF1A promoter region. Vice versa, RASSF1A binds to HIF-1α, blocks its prolyl-hydroxylation and proteasomal degradation, and thus enhances the activation of the glycolytic switch. We find that this mechanism operates in experimental hypoxia-induced PH, which is blocked in RASSF1A knockout mice, in human primary PH vascular cells, and in a subset of human lung cancer cells. We conclude that RASSF1A-HIF-1α forms a feedforward loop driving hypoxia signaling in PH and cancer.

DOI: https://doi.org/10.1038/s41467-019-10044-z
Biochem Pharmacol. 2019 May 11. pii: S0006-2952(19)30182-0. [Epub ahead of print]

UCP2 regulates cholangiocarcinoma cell plasticity via mitochondria-to-AMPK signals.

Jianhua Yu, Lawrence Shi, Xinggui Shen, Yunfeng Zhao.

  Uncoupling protein 2 (UCP2) is upregulated in several human cancers which contributes to tumorigenesis. However, whether UCP2 expression is amplified in cholangiocarcinoma and whether UCP2 promotes cholangiocarcinoma progression are not known. Our results found that in human cholangiocarcinoma tissues, UCP2 was highly expressed in tumors and its levels were negatively associated with prognosis. Importantly, lymph node invasion of cholangiocarcinoma was associated with higher UCP2 expression. In cholangiocarcinoma cells, cell proliferation and migration were suppressed when UCP2 expression was inhibited via gene knockdown. In UCP2 knockdown cells, glycolysis was inhibited, the mesenchymal markers were downregulated whereas AMPK was activated. The increased mitochondrial ROS and AMP/ATP ratio might be responsible for this activation. When the UCP2 inhibitor genipin was applied, tumor cell migration and 3D growth were suppressed via enhancing the mesenchymal-epithelial transition of cholangiocarcinoma cells. Furthermore, cholangiocarcinoma cells became sensitive to cisplatin and gemcitabine treatments when genipin was applied. In conclusion, our results demonstrate that the amplified expression of UCP2 contributes to the progression of cholangiocarcinoma through a glycolysis-mediated mechanism.

Keywords:  Cholangiocarcinoma; EMT; Glycolysis; Mitochondrial ROS; UCP2

DOI:  https://doi.org/10.1016/j.bcp.2019.05.017