Paradoxical roles of dual oxidases in cancer biology

Transcriptomic analysis reveals oxidative stress-related signature and molecular subtypes in cholangio carcinoma

Cholangiocarcinoma (CCA) is a heterogeneous and aggressive malignancy with limited therapeutic options and poor prognosis. The identification of reliable prognostic biomarkers and a deeper understanding of the molecular subtypes are critical for the development of targeted therapies and improvement of patient outcomes. This study aims to uncover oxidative stress-related genes (ORGs) in CCA and develop a prognostic risk model using comprehensive transcriptomic analysis from The Cancer Genome Atlas (TCGA). Through LASSO regression analysis, we identified prognosis-related ORGs and constructed a prognostic signature consisting of six ORGs. This signature demonstrated strong predictive performance in survival analysis and ROC curve assessment. Functional enrichment and GSEA analyses revealed significant enrichment of immune-related pathways among different risk groups. GSVA analysis indicated reduced activity in inflammation and oxidative stress pathways in the high-risk subgroup, and xCell results showed lower immune cell infiltration levels in this group. Additionally, immune checkpoint genes and immune-related pathways were downregulated in the high-risk subgroup. Our research has developed a unique prognostic model focusing on oxidative stress, enabling accurate forecasting of patient outcomes and providing crucial insights and recommendations for the prognosis of individuals with CCA. Future studies should aim to validate these findings in clinical settings and further explore therapeutic targets within oxidative stress pathways.

The Role of Nrf2 in the Regulation of Mitochondrial Function and Ferroptosis in Pancreatic Cancer

The transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) represents the master regulator of the cellular antioxidant response and plays a critical role in tumorigenesis. This includes a preventive effect of Nrf2 on cell death through ferroptosis, which represents an essential mechanism of therapy resistance in malignant tumors, such as pancreatic ductal adenocarcinoma (PDAC) as one of the most aggressive and still incurable tumors. Addressing this issue, we provide an overview on Nrf2 mediated antioxidant response with particular emphasis on its effect on mitochondria as the organelle responsible for the execution of ferroptosis. We further outline how deregulated Nrf2 adds to the progression and therapy resistance of PDAC, especially with respect to the role of ferroptosis in anti-cancer drug mediated cell killing and how this is impaired by Nrf2 as an essential mechanism of drug resistance. Our review further discusses recent approaches for Nrf2 inhibition by natural and synthetic compounds to overcome drug resistance based on enhanced ferroptosis. Finally, we provide an outlook on therapeutic strategies based on Nrf2 inhibition combined with ferroptosis inducing drugs.

Ferroptosis-related genes DUOX1 and HSD17B11 affect tumor microenvironment and predict overall survival of lung adenocarcinoma patients

BACKGROUND

Recent studies have found that ferroptosis-related genes (FRGs) have broad applications in tumor therapy. However, the predictive potential of these genes in lung adenocarcinoma (LUAD) remains to be fully characterized. We aimed to investigate the FRGs that might be potential targets for LUAD.

METHODS

We screened the RNA sequencing samples from LUAD patients from the GEO database and analyzed the ferroptosis-related differentially expressed genes (DEGs). A functional analysis of DEGs was performed. The risk model was constructed to evaluation and validation FRGs. We explored the immune landscape of LUAD and controls. The value of FRGs in diagnosing LUAD was tested in the GSE30219, GSE37745, GSE0081 datasets, and qPCR was used to verify their diagnostic value in LUAD patients in our hospital.

RESULTS

A total of 1327 DEGs in quantitative proteomics were obtained, of which ferroptosis-related DEGs were 259. Enrichment analysis showed significant enrichment in the absorption and metabolism of fatty acids and arachidonic acid. The upregulated genes (GCLC, RRM2, AURKA, SLC7A5, and SLC2A1) and downregulated genes (ANGPTL7, ALOX15, ALOX15B, HSD17B11, IL33, TSC22D3, and DUOX1) were selected as core genes in tissue samples from 62 patients by qPCR. DUOX1 and HSD17B11 were obtained by bioinformatics analysis, both of which showed similar expression trends at the RNA and protein levels. The Kaplan-Meier method showed that DUOX1 and HSD17B11 were closely related to the overall survival (OS) of LUAD patients.

CONCLUSION SUBSECTIONS

Ferroptosis-related genes DUOX1 and HSD17B11 are of considerable value in the diagnosis of LUAD patients. Their low expression suggests an increased recurrence rate and leads to a decrease in the patient quality of life.

Menadione and protocatechuic acid: A drug combination with antitumor effects in murine osteosarcoma cells

Osteosarcoma (OS) is a primary malignant bone tumor that has an abnormal expression of oncogenesis and tumor suppressors and causes dysregulation of various signaling pathways. Thus, novel therapeutic strategies for OS are needed to overcome the resistance of traditional treatments. This study evaluated the cytotoxic and anticancer effects of the association between menadione (MEN) and protocatechuic acid (PCA) in murine OS cells (UMR-106). The concentrations were 3.12 μM of isolated MEN, 500 μM of isolated PCA, and their associations. We performed cell viability assays, morphology modification analysis, cell migration by the wound-healing method, apoptosis by flow cytometry, reactive oxygen species (ROS) production, gene expression of NOX by RT-qPCR, and degradation of MMP-2 and 9 by zymography. Our results showed that the association of MEN+PCA was more effective in OS cells than the compounds alone. The association decreased cell viability, delayed cell migration, and decreased the expression of NOX-2 and ROS. In addition, the MEN+PCA association induced a slight increase in the apoptotic process. In summary, the association can enhance the compound's antitumor effects and establish a higher selectivity for tumor cells, possibly caused by significant mitochondrial damage and antioxidant properties.

A noncanonical response to replication stress protects genome stability through ROS production, in an adaptive manner

Cells are inevitably challenged by low-level/endogenous stresses that do not arrest DNA replication. Here, in human primary cells, we discovered and characterized a noncanonical cellular response that is specific to nonblocking replication stress. Although this response generates reactive oxygen species (ROS), it induces a program that prevents the accumulation of premutagenic 8-oxoguanine in an adaptive way. Indeed, replication stress-induced ROS (RIR) activate FOXO1-controlled detoxification genes such as SEPP1, catalase, GPX1, and SOD2. Primary cells tightly control the production of RIR: They are excluded from the nucleus and are produced by the cellular NADPH oxidases DUOX1/DUOX2, whose expression is controlled by NF-κB, which is activated by PARP1 upon replication stress. In parallel, inflammatory cytokine gene expression is induced through the NF-κB-PARP1 axis upon nonblocking replication stress. Increasing replication stress intensity accumulates DNA double-strand breaks and triggers the suppression of RIR by p53 and ATM. These data underline the fine-tuning of the cellular response to stress that protects genome stability maintenance, showing that primary cells adapt their responses to replication stress severity.

Modulation of Reactive Oxygen Species in Cancers: Recent Advances

Oxidation-reduction reactions played a significant role in the chemical evolution of life forms on oxygenated earth. Cellular respiration is dependent on such redox reactions, and any imbalance leads to the accumulation of reactive oxygen species (ROS), resulting in both chronic and acute illnesses. According to the International Agency for Research on Cancer (IARC), by 2040, the global burden of new cancer cases is expected to be around 27.5 million, with 16.3 million cancer deaths due to an increase in risk factors such as unhealthy lifestyle, environmental factors, aberrant gene mutations, and resistance to therapies. ROS play an important role in cellular signalling, but they can cause severe damage to tissues when present at higher levels. Elevated and chronic levels of ROS are pertinent in carcinogenesis, while several therapeutic strategies rely on altering cellular ROS to eliminate tumour cells as they are more susceptible to ROS-induced damage than normal cells. Given this selective targeting potential, therapies that can effectively modulate ROS levels have been the focus of intense research in recent years. The current review describes biologically relevant ROS, its origins in solid and haematological cancers, and the current status of evolving antioxidant and pro-oxidant therapies in cancers.

The dimerization of methyl vanillate improves its effect against breast cancer cells via pro-oxidant effect

Phenolic phytochemicals are a group of organic compounds with potent antioxidant features but can also act as powerful pro-oxidants. These characteristics are effective in reducing metastatic potential in cancer cells, and this effect has been associated with reactive oxygen species (ROS). Methyl vanillate (MV) and its dimer, methyl divanillate (DMV), are potent antioxidants. In the present study, we investigated the effects of MV and DMV on breast cancer cell lines MCF-7 and MDA-MB-231 and compared the results using the non-tumor cell line HB4a. Our results indicated that the compounds performed a pro-oxidant action, increasing the generation of ROS. DMV decreased the viability cell, showing a higher apoptotic effect and inhibition of proliferation than MV on both cell lines, with significant differences between groups (p < 0.05). Some modulation of NOX4, NOX5, and DUOX were observed, but the results did not correlate with the intracellular production of ROS. The dimer showed more effectivity and pro-oxidant effect than MV, impacting cell line MCF-7 in higher extension than MDA-MB-231. In conclusion, and corroborating with reported works, the dimerization of natural phenolic compounds was associated with improved beneficial biological effects as a potential cytotoxic agent to tumor cells.

The interplay between reactive oxygen species and antioxidants in cancer progression and therapy: a narrative review

Objective

To unveil the role of reactive oxygen species (ROS) and antioxidants in signaling and involvement in cancer progression and therapy.

Background

Cancer is considered one of the main causes of mortality in developed countries and expected to be more in developing countries as well. Although some cancers may develop at young age, yet almost all types of cancers are an accumulation of genetic and epigenetic cell damages. Cancer is considered a diverse collection of diseases on a cellular level rather than a single disease; and each disease has a different cause as well. ROS have been seen as harmful toxic molecules; however, they are recognized for cellular signaling capabilities. Elevated levels of ROS have protumorigenic activities; they induce cancer cell proliferation, and adaptation to hypoxia in addition to other effects like DNA damage and genetic instability. They are produced excessively by cancer cells to hyperactivate cellular transformation meanwhile increasing antioxidant capacity to avoid cell death.

Methods

We discussed peer reviewed published research work from 1987 to 2021. In this paper, we review the role of antioxidants as defensive barrier against excessive ROS levels for maintaining oxidation-reduction (redox) balance; however, antioxidant can also strive in tumor cells with their scavenging capacities and maintain protumorigenic signaling and resist the cancer cell oxidative stress and apoptosis. High doses of antioxidant compounds could be toxic to cells as they are capable of reacting with the physiological concentrations of ROS present for normal cellular processes and signaling.

Conclusions

Maintaining cellular redox homeostasis is vital for healthy biological system. Therefore, therapeutic modalities for cancer including antioxidants and ROS management should be used at certain doses to target specific redox pathways involved in cancer progression without disrupting the overall redox balance in normal cells.

A Ferroptosis-Related Prognostic Risk Score Model to Predict Clinical Significance and Immunogenic Characteristics in Glioblastoma Multiforme

Background

Ferroptosis is a recently identified cell death pathway, and the susceptibility to ferroptosis inducers varies among cancer cell types. There have been recent attempts to clarify the mechanisms implicated in ferroptosis, glioma invasion, and the immune microenvironment but little is known about ferroptosis regulation in GBM.

Methods

Screening ferroptosis-related genes from published reports and existing databases, we constructed an integrated model based on the RNA-sequencing data in GBM. The association of FRGPRS and overall survival is identified and validated across several different datasets. Genomic and clinical characteristics, immune infiltration, enriched pathways, pan-cancer, drug resistance, and immune checkpoint inhibitor therapy are compared among various FRGPRS subgroups.

Results

We identified and confirmed the influences of five ferroptosis key hub genes in the FRGPRS model. The FRGPRS model could serve to predict overall survival and progression-free survival in GBM patients, and high FRGPRS was associated with comparatively stronger immunity, higher proportions of tumour tissue, and good cytolytic immune and chemotherapeutics response in GBM patients.

Conclusions

The five ferroptosis key hub genes constituting the FRGPRS model could serve to predict overall survival and progression-free survival in patients with GBM and help guide timely and efficacious therapeutic strategies customised and optimised for each individual patient. This discovery may lay the foundation for the development and optimisation of other iterations of this model for the improved forecasting, detection, and treatment of other malignancies notorious for their drug resistance and immune escape.

DUOX1 in mammalian disease pathophysiology

Dual oxidase 1 (DUOX1) is a member of the protein family of nicotinamide adenine dinucleotide phosphate (NADPH) oxidases. DUOX1 has several normal physiological, immunological, and biochemical functions in different parts of the body. Dysregulated oxidative metabolism interferes with various disease pathologies and numerous therapeutic options are based on targeting cellular redox pathways. DUOX1 forms an important enzymatic source of biological oxidants, and DUOX1 expression is frequently dysregulated in various diseases. While this review shortly addresses the biochemical and cellular properties and proposed physiological roles of DUOX1, its main purpose is to summarize the current knowledge with respect to the potential role of DUOX1 enzyme in disease pathology, especially in mammalian organisms. Although DUOX1 is normally prominently expressed in epithelial lineages, it is frequently silenced in epithelial-derived cancers by epigenetic mechanisms. While an abundance of information is available on DUOX1 transcription in different diseases, an increasing number of mechanistic studies indicate a causative relationship between DUOX1 function and disease pathophysiology. Additionally, specific functions of the DUOX1 maturation factor, DUOXA1, will also be addressed. Lastly, urgent and outstanding questions on the field of DUOX1 will be discussed that could provide valuable new diagnostic tools and novel therapeutic options.

The Role of Reactive Oxygen Species in Tumor Treatment and its Impact on Bone Marrow Hematopoiesis

Reactive oxygen species (ROS), an important molecule inducing oxidative stress in organisms, play a key role in tumorigenesis, tumor progression and recurrence. Recent findings on ROS have shown that ROS can be used to treat cancer as they accelerate the death of tumor cells. At present, pro-oxidant drugs that are intended to increase ROS levels of the tumor cells have been widely used in the clinic. However, ROS are a double-edged sword in the treatment of tumors. High levels of ROS induce not only the death of tumor cells but also oxidative damage to normal cells, especially bone marrow hemopoietic cells, which leads to bone marrow suppression and (or) other side effects, weak efficacy of tumor treatment and even threatening patients' life. How to enhance the killing effect of ROS on tumor cells while avoiding oxidative damage to the normal cells has become an urgent issue. This study is a review of the latest progress in the role of ROS-mediated programmed death in tumor treatment and prevention and treatment of oxidative damage in bone marrow induced by ROS.

PKCδ mediates mitochondrial ROS generation and oxidation of HSP60 to relieve RKIP inhibition on MAPK pathway for HCC progression

Both protein kinase C (PKC) and reactive oxygen species (ROS) are well-known signaling messengers cross-talking with each other to activate mitogen-activated protein kinases (MAPKs) for progression of hepatocellular carcinoma (HCC). However, the underlying mechanisms are not well elucidated. Especially, whether mitochondrial ROS (mtROS) is involved and how it triggers MAPK signaling are intriguing. In this study, we found mtROS generation and phosphorylation of MAPKs were mediated by PKCδ in HCCs treated with the tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate (TPA). Heat shock protein 60 (HSP60), one of the chaperones in mitochondria was the major protein oxidized in TPA-treated HCCs. Moreover, depletion of HSP60 or expression of HSP60 cysteine mutant prevented TPA-induced phosphorylation of MAPKs. To delineate how HSP60 mediated MAPK activation, the role of Raf kinase inhibitor protein (RKIP), a negative regulator of MAPK, was investigated. TPA dissociated RKIP from HSP60 in both mitochondria and cytosol, concurrently with translocation of HSP60 and MAPK from mitochondria to cytosol, which was associated with robust phosphorylation of MAPKs in the cytosol. Moreover, TPA induced opposite phenotypical changes of HCCs, G1 cell cycle arrest, and cell migration, which were prevented by mtROS scavengers and depletion of PKCδ and HSP60. Consistently, TPA increased the migration-related genes, hydrogen peroxide inducible clone5, matrix metalloproteinase-1/3, lamininγ2, and suppressed the cell cycle regulator cyclin E1 (CCNE1) via PKCδ/mtROS/HSP60/MAPK-axis. Finally, c-jun and c-fos were required for TPA-induced expression of the migration-related genes and a novel microRNA, miR-6134, was responsible for TPA-induced suppression of CCNE1. In conclusion, PKCδ cross-talked with mtROS to trigger HSP60 oxidation for release of RKIP to activate MAPK, regulating gene expression for migration, and G1 cell cycle arrest in HCC. Targeted therapy aiming at key players like PKCδ, RKIP, and HSP60 is promising for preventing HCC progression.

DUOX2 participates in skin aging induced by UVB in HSF2 cells by activating NF-κB signaling

Skin and in particular photoaging or premature aging, are caused by a variety of factors, including hormone imbalance and exposure to ultraviolet radiation. The aim of the present study was to explore the roles of Dual oxidase 2 (DUOX2) and related NF-κB signals in skin photoaging. Cell models of photoaging were constructed by irradiating human skin fibroblast lines (HSF2) with ultraviolet B (UVB) of different doses (0, 15, 30 and 60 mj/cm²). The cell counting kit-8 (CCK8) was used to determine cell proliferation. Flow cytometry was used to determine the production of reactive oxygen species (ROS). A biochemical method was to determine the content of hydrogen peroxide, and the quantitative PCR (qPCR) was used to determine the expression of matrix metalloproteinase 2 (MMP2), matrix metalloproteinase 9 (MMP9), Col-Ⅰ and α-SMA in the cells. Enzyme-linked immunosorbent assay (ELISA) was used to determine the expression of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). Western blot analysis was performed to determine the expression of DUOX2, p65 and p-p65. The results showed that,UVB irradiation dose- and time-dependently inhibited the proliferation of HSF2 cells. Cellular inflammatory response, ROS production and hydrogen peroxide increase was promoted. Col-Ⅰ and α-SMA were downregulated, MMP2 and MMP9 were upregulated, and the phosphorylation of NF-κB p65 was promoted. The above indicators were all reversed by interference with DUOX2. Overexpression of DUOX2 has an effect that is similar to UVB irradiation, but the effects can be significantly weakened by NF-κB inhibitor, NAC. Upregulation of DUOX2 expression plays a crucial role in UVB-induced aging of HSF2 cells. The specific mechanism is related to the promotion of ROS production and cellular inflammatory response and activation of NF-κB signals.

Exploring redox vulnerabilities in JAK2V617F-positive cellular models

Background

In Philadelphia chromosome-negative myeloproliferative neoplasm (MPN) models, reactive oxygen species (ROS) are elevated and have been implicated in genomic instability, JAK2/STAT signaling amplification, and disease progression. Although the potential effects of ROS on the MPN phenotype, the effects of ruxolitinib treatment on ROS regulation have been poorly explored. Herein, we have reported the impact of ruxolitinib on redox signaling transcriptional network, and the effects of diphenyleneiodonium (DPI), a pan NOX inhibitor, in JAK2^V617F-driven cellular models.

Method

Redox signaling-related genes were investigated in SET2 cells upon ruxolitinib treatment by RNA-seq (GEO accession GSE69827). SET2 and HEL cells, which represent JAK2^V617F-positive MPN cellular models with distinct sensitivity to apoptosis induced by ruxolitinib, were used. Cell viability was evaluated by MTT, apoptosis by annexin V/PI and flow cytometry, and cell signaling by quantitative PCR and Western blot.

Main results

Ruxolitinib impacted on a network composed of redox signaling-related genes, and DUOX1 and DUOX2 were identified as potential modulators of ruxolitinib response. In SET2 and HEL cells, DPI reduced cell viability and, at low doses, it significantly potentiated ruxolitinib-induced apoptosis. In the molecular scenario, DPI inhibited STAT3, STAT5 and S6 ribosomal protein phosphorylation and induced PARP1 cleavage in JAK2^V617F-positive cells. DPI combined with ruxolitinib increased PARP1 cleavage in SET2 cells and potentiated ruxolitinib-reduced STAT3, STAT5 and S6 ribosomal protein in HEL cells.

Conclusion

Our study reveals a potential adaptation mechanism for resistance against ruxolitinib by transcriptionally reprogramming redox signaling in JAK2^V617F cells and exposes redox vulnerabilities with therapeutic value in MPN cellular models.

The role of NOX4 in pulmonary diseases

Nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX4) is a subtype of the NOX family, which is mainly expressed in the pulmonary vasculature and pulmonary endothelial cells in the respiratory system. NOX4 has unique characteristics, and is a constitutively active enzyme that primarily produces hydrogen peroxide. The signaling pathways associated with NOX4 are complicated. Negative and positive feedback play significant roles in regulating NOX4 expression. The role of NOX4 is controversial because NOX4 plays a protective or damaging role in different respiratory diseases. This review summarizes the structure, enzymatic properties, regulation, and signaling pathways of NOX4. This review then introduces the roles of NOX4 in different diseases in the respiratory system, such as acute respiratory distress syndrome, chronic obstructive pulmonary disease, and pulmonary fibrosis.

Molecular characterization of AwSox2 from bivalve Anodonta woodiana: Elucidating its player in the immune response

Sox2 is an embryonal stem cell Ag essential for early embryonic development, tissue homeostasis and immune regulation. In the current study, one complete Sox2 cDNA sequence was cloned from freshwater bivalve Anodonta woodiana and named AwSox2. Histological changes of testis derived from Bisphenol A (BPA) treatment were analyzed by hematoxylin and eosin staining. Expressions of AwSox2 derived from BPA, LPS and polyinosinic:polycytidylic (Poly I:C) challenge were measured by quantitative real-time PCR. The full-length cDNA of AwSox2 contained an open reading frame of 927 nucleotides bearing the typical structural features of Sox2 family. Obvious degeneration, irregular arrangement of spermatids, and clotted dead and intertwined spermatids were observed in BPA-treated groups. Administration of BPA could result in a dose-dependent up-regulation of AwSox2 expression in the male gonadal tissue of A. woodiana. In addition, expression of AwSox2 was significantly induced by LPS and Poly I:C treatment in the hepatopancreas, gill and hemocytes, compared with that of control group. These results indicated that up-regulations of AwSOx2 are closely related to apoptosis of spermatogonial stem cells derived from BPA treatment as well as enhancement of immune defense against LPS and Poly I:C challenge in A. woodiana.

Dual oxidase 1 and NADPH oxidase 2 exert favorable effects in cervical cancer patients by activating immune response

BACKGROUND

Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase-derived reactive oxygen species (ROS) not only can promote cancer progression, but also they have recently emerged as mediators of the mucosal immune system. However, the roles and clinical relevance of the collective or individual NADPH oxidase (NOX) family genes in cervical cancer have not been studied.

METHODS

We investigated the clinical significance of the NOX family genes using data from 307 patients with cervical cancer obtained from The Cancer Genome Atlas. Bioinformatics and experimental analyses were performed to examine NOX family genes in cervical cancer patients.

RESULTS

Dual Oxidase1 (DUOX1) and Dual Oxidase 2 (DUOX2) mRNA levels were upregulated 57.9- and 67.5-fold, respectively, in cervical cancer patients. The protein expression of DUOX1, DUOX2, and NOX2 also identified in cervical squamous cell carcinoma tissues. Especially, DUOX1 and DUOX2 mRNA levels were significantly increased in patients infected with human papillomavirus (HPV) 16. Moreover, high DUOX1 mRNA levels were significantly associated with both favorable overall survival and disease-free survival in cervical cancer patients. High NOX2 mRNA levels was significantly associated with favorable overall survival. Gene set enrichment analyses revealed that high DUOX1 and NOX2 expression was significantly correlated with the enrichment of immune pathways related to interferon (IFN)-alpha, IFN-gamma, and natural killer (NK) cell signaling. Cell-type identification by estimating relative subsets of known RNA transcript analyses indicated that the fraction of innate immune cells, including NK cells, monocytes, dendritic cells, and mast cells, was elevated in patients with high DUOX1 expression.

CONCLUSIONS

DUOX1 and NOX2 expression are associated with mucosal immunity activated in cervical squamous cell carcinoma and predicts a favorable prognosis in cervical cancer patients.

Redox signaling in aging kidney and opportunity for therapeutic intervention through natural products

Kidney diseases are serious public problems with high morbidity and mortality in the general population and heavily retard renal function with aging regardless of the cause. Although myriad strategies have been assigned to prevent or harness disease progression, unfortunately, thus far, there is a paucity of effective therapies partly due to an insufficient knowledge of underlying pathological mechanisms, indicating deeper studies are urgently needed. Additionally, natural products are increasingly recognized as an alternative source for disease intervention owing to the potent safety and efficacy, which might be exploited for novel drug discovery. In this review, we primarily expatiate the new advances on mediators that might be amenable to targeting aging kidney and kidney diseases, including nicotinamide adenine dinucleotide phosphate oxidase (NOX), transforming growth factor-β (TGF-β), renin-angiotensin system (RAS), nuclear factor-erythroid 2 related factor 2 (Nrf2), peroxisome proliferator-activated γ receptor (PPARγ), advanced glycation endproducts (AGEs) as well as microRNAs and vitagenes. Of note, we conclude by highlighting some natural products which have the potential to facilitate the development of novel treatment for patients with myriad renal diseases.

Hydrogen peroxide-producing NADPH oxidases and the promotion of migratory phenotypes in cancer

The cellular microenvironment plays a critical role in cancer initiation and progression. Exposure to oxidative stress, specifically hydrogen peroxide (H₂O₂), has been linked to aberrant cellular signaling through which the development of cancer may be promoted. Three members of the NADPH oxidase family (NOX4, DUOX1 and DUOX2) explicitly generate this non-radical oxidant in a wide range of tissues, often in support of the inflammatory response. This review summarizes the contributions of each H₂O₂-producing NOX to the invasive behaviors of tumors and/or the epithelial-mesenchymal transition (EMT) in cancer that plays an essential role in metastasis. Tissue localization in tumorigenesis is also highlighted, with patient-derived TCGA microarray data profiled across 31 cancer cohorts to provide a comprehensive guide to the relevance of NOX4/DUOX1/DUOX2 in cancer studies.

Dysregulated Redox Regulation Contributes to Nuclear EGFR Localization and Pathogenicity in Lung Cancer

Lung cancers are frequently characterized by inappropriate activation of epidermal growth factor receptor (EGFR)-dependent signaling and epigenetic silencing of the NADPH oxidase (NOX) enzyme DUOX1, both potentially contributing to worse prognosis. Based on previous findings linking DUOX1 with redox-dependent EGFR activation, the present studies were designed to evaluate whether DUOX1 silencing in lung cancers may be responsible for altered EGFR regulation. In contrast to normal epithelial cells, EGF stimulation of lung cancer cell lines that lack DUOX1 promotes EGF-induced EGFR internalization and nuclear localization, associated with induction of EGFR-regulated genes and related tumorigenic outcomes. Each of these outcomes could be reversed by overexpression of DUOX1 or enhanced by shRNA-dependent DUOX1 silencing. EGF-induced nuclear EGFR localization in DUOX1-deficient lung cancer cells was associated with altered dynamics of cysteine oxidation of EGFR, and an overall reduction of EGFR cysteines. These various outcomes could also be attenuated by silencing of glutathione S-transferase P1 (GSTP1), a mediator of metabolic alterations and drug resistance in various cancers, and a regulator of cysteine oxidation. Collectively, our findings indicate DUOX1 deficiency in lung cancers promotes dysregulated EGFR signaling and enhanced GSTP1-mediated turnover of EGFR cysteine oxidation, which result in enhanced nuclear EGFR localization and tumorigenic properties.

When safeguarding goes wrong: Impact of oxidative stress on protein homeostasis in health and neurodegenerative disorders

Cellular redox status is an established player in many different cellular functions. The buildup of oxidants within the cell is tightly regulated to maintain a balance between the positive and negative outcomes of cellular oxidants. Proteins are highly sensitive to oxidation, since modification can cause widespread unfolding and the formation of toxic aggregates. In response, cells have developed highly regulated systems that contribute to the maintenance of both the global redox status and protein homeostasis at large. Changes to these systems have been found to correlate with aging and age-related disorders, such as neurodegenerative pathologies. This raises intriguing questions as to the source of the imbalance in the redox and protein homeostasis systems, their interconnectivity, and their role in disease progression. Here we focus on the crosstalk between the redox and protein homeostasis systems in neurodegenerative diseases, specifically in Alzheimer's, Parkinson's, and ALS. We elaborate on some of the main players of the stress response systems, including the master regulators of oxidative stress and the heat shock response, Nrf2 and Hsf1, which are essential features of protein folding, and mediators of protein turnover. We illustrate the elegant mechanisms used by these components to provide an immediate response, including protein plasticity controlled by redox-sensing cysteines and the recruitment of naive proteins to the redox homeostasis array that act as chaperons in an ATP-independent manner.

Clair WH, St. Clair DK. Redox Paradox: A Novel Approach to Therapeutics-Resistant Cancer

SIGNIFICANCE

Cancer cells that are resistant to radiation and chemotherapy are a major problem limiting the success of cancer therapy. Aggressive cancer cells depend on elevated intracellular levels of reactive oxygen species (ROS) to proliferate, self-renew, and metastasize. As a result, these aggressive cancers maintain high basal levels of ROS compared with normal cells. The prominence of the redox state in cancer cells led us to consider whether increasing the redox state to the condition of oxidative stress could be used as a successful adjuvant therapy for aggressive cancers. Recent Advances: Past attempts using antioxidant compounds to inhibit ROS levels in cancers as redox-based therapy have met with very limited success. However, recent clinical trials using pro-oxidant compounds reveal noteworthy results, which could have a significant impact on the development of strategies for redox-based therapies.

CRITICAL ISSUES

The major objective of this review is to discuss the role of the redox state in aggressive cancers and how to utilize the shift in redox state to improve cancer therapy. We also discuss the paradox of redox state parameters; that is, hydrogen peroxide (H2O2) as the driver molecule for cancer progression as well as a target for cancer treatment.

FUTURE DIRECTIONS

Based on the biological significance of the redox state, we postulate that this system could potentially be used to create a new avenue for targeted therapy, including the potential to incorporate personalized redox therapy for cancer treatment.

Oxidative stress in chronic lung disease: From mitochondrial dysfunction to dysregulated redox signaling

The lung is a delicate organ with a large surface area that is continuously exposed to the external environment, and is therefore highly vulnerable to exogenous sources of oxidative stress. In addition, each of its approximately 40 cell types can also generate reactive oxygen species (ROS), as byproducts of cellular metabolism and in a more regulated manner by NOX enzymes with functions in host defense, immune regulation, and cell proliferation or differentiation. To effectively regulate the biological actions of exogenous and endogenous ROS, various enzymatic and non-enzymatic antioxidant defense systems are present in all lung cell types to provide adequate protection against their injurious effects and to allow for appropriate ROS-mediated biological signaling. Acute and chronic lung diseases are commonly thought to be associated with increased oxidative stress, evidenced by altered cellular or extracellular redox status, increased irreversible oxidative modifications in proteins or DNA, mitochondrial dysfunction, and altered expression or activity of NOX enzymes and antioxidant enzyme systems. However, supplementation strategies with generic antioxidants have been minimally successful in prevention or treatment of lung disease, most likely due to their inability to distinguish between harmful and beneficial actions of ROS. Recent studies have attempted to identify specific redox-based mechanisms that may mediate chronic lung disease, such as allergic asthma or pulmonary fibrosis, which provide opportunities for selective redox-based therapeutic strategies that may be useful in treatment of these diseases.

Peroxidasin-mediated crosslinking of collagen IV is independent of NADPH oxidases

Collagen IV is a major component of the basement membrane in epithelial tissues. The NC1 domains of collagen IV protomers are covalently linked together through sulfilimine bonds, the formation of which is catalyzed by peroxidasin. Although hydrogen peroxide is essential for this reaction, the exact source of the oxidant remains elusive. Members of the NOX/DUOX NADPH oxidase family are specifically devoted to the production of superoxide and hydrogen peroxide. Our aim in this study was to find out if NADPH oxidases contribute in vivo to the formation of collagen IV sulfilimine crosslinks. We used multiple genetically modified in vivo model systems to provide a detailed assessment of this question. Our data indicate that in various peroxidasin-expressing tissues sulfilimine crosslinks between the NC1 domains of collagen IV can be readily detected in the absence of functioning NADPH oxidases. We also analyzed how subatmospheric oxygen levels influence the collagen IV network in collagen-producing cultured cells with rapid matrix turnover. We showed that collagen IV crosslinks remain intact even under strongly hypoxic conditions. Our hypothesis is that during collagen IV network formation PXDN cooperates with a NOX/DUOX-independent H2O2 source that is functional also at very low ambient oxygen levels.

Antimicrobial actions of dual oxidases and lactoperoxidase

The NOX/DUOX family of NADPH oxidases are transmembrane proteins generating reactive oxygen species as their primary enzymatic products. NADPH oxidase (NOX) 1-5 and Dual oxidase (DUOX) 1 and 2 are members of this family. These enzymes have several biological functions including immune defense, hormone biosynthesis, fertilization, cell proliferation and differentiation, extracellular matrix formation and vascular regulation. They are found in a variety of tissues such as the airways, salivary glands, colon, thyroid gland and lymphoid organs. The discovery of NADPH oxidases has drastically transformed our view of the biology of reactive oxygen species and oxidative stress. Roles of several isoforms including DUOX1 and DUOX2 in host innate immune defense have been implicated and are still being uncovered. DUOX enzymes highly expressed in the respiratory and salivary gland epithelium have been proposed as the major sources of hydrogen peroxide supporting mucosal oxidative antimicrobial defenses. In this review, we shortly present data on DUOX discovery, structure and function, and provide a detailed, up-to-date summary of discoveries regarding antibacterial, antiviral, antifungal, and antiparasitic functions of DUOX enzymes. We also present all the literature describing the immune functions of lactoperoxidase, an enzyme working in partnership with DUOX to produce antimicrobial substances.

Gene expression and prognosis of NOX family members in gastric cancer

INTRODUCTION

Nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOX) are frequently deregulated in several human malignancies, including gastric cancer (GC). NOX-derived reactive oxygen species have been reported to contribute to gastric carcinogenesis and cancer progression. However, the expression and prognostic role of individual NOX in GC patients remain elusive.

METHODS AND MATERIALS

We investigated genetic alteration and mRNA expression of NOX family in GC patients via the cBioPortal, Human Protein Atlas, and Oncomine databases. Furthermore, we evaluated prognostic value of distinct NOX in GC patients through "The Kaplan-Meier plotter" database.

RESULTS

Our analysis demonstrated that mRNA deregulation of NOX genes was common alteration in GC patients. Compared with normal tissues, NOX1/2/4 mRNA expression levels in GC tissues were higher, while NOX5 and DUOX1/2 expression levels were lower. Importantly, our results indicated that high mRNA expression of NOX2 was associated with better overall survival whereas NOX4 and DUOX1 were correlated with worse overall survival in all GC patients, particularly in intestinal-type GC patients. In addition, our data also shed light on the diverse roles of individual NOX members in GC patients with different clinicopathological features, including human epidermal growth factor receptor 2 status, clinical stages, pathological grades, and different choices of treatments of GC patients.

CONCLUSION

These findings suggest that individual NOX family genes, especially NOX2/4, and DUOX1, are potential prognostic markers in GC and implicate that the use of NOX inhibitor targeting NOX4 and DUOX1 may be an effective strategy for GC therapy.

Dual oxidase: a novel therapeutic target in allergic disease

NADPH oxidases (NOXs) represent a family of enzymes that mediate regulated cellular production of reactive oxygen species (ROS) and play various functional roles in physiology. Among the NOX family, the dual oxidases DUOX1 and DUOX2 are prominently expressed in epithelial cell types at mucosal surfaces and have therefore been considered to have important roles in innate host defence pathways. Recent studies have revealed important insights into the host defence mechanisms of DUOX enzymes, which control innate immune response pathways in response to either microbial or allergic triggers. In this review, we discuss the current level of understanding with respect to the biological role(s) of DUOX enzymes and the unique role of DUOX1 in mediating innate immune responses to epithelial injury and allergens and in the development of allergic disease. These novel findings highlight DUOX1 as an attractive therapeutic target, and opportunities for the development of selective inhibitor strategies will be discussed.

Insights on Localized and Systemic Delivery of Redox-Based Therapeutics

Reactive oxygen and nitrogen species are indispensable in cellular physiology and signaling. Overproduction of these reactive species or failure to maintain their levels within the physiological range results in cellular redox dysfunction, often termed cellular oxidative stress. Redox dysfunction in turn is at the molecular basis of disease etiology and progression. Accordingly, antioxidant intervention to restore redox homeostasis has been pursued as a therapeutic strategy for cardiovascular disease, cancer, and neurodegenerative disorders among many others. Despite preliminary success in cellular and animal models, redox-based interventions have virtually been ineffective in clinical trials. We propose the fundamental reason for their failure is a flawed delivery approach. Namely, systemic delivery for a geographically local disease limits the effectiveness of the antioxidant. We take a critical look at the literature and evaluate successful and unsuccessful approaches to translation of redox intervention to the clinical arena, including dose, patient selection, and delivery approach. We argue that when interpreting a failed antioxidant-based clinical trial, it is crucial to take into account these variables and importantly, whether the drug had an effect on the redox status. Finally, we propose that local and targeted delivery hold promise to translate redox-based therapies from the bench to the bedside.

Redox control of cancer cell destruction

Redox regulation has been proposed to control various aspects of carcinogenesis, cancer cell growth, metabolism, migration, invasion, metastasis and cancer vascularization. As cancer has many faces, the role of redox control in different cancers and in the numerous cancer-related processes often point in different directions. In this review, we focus on the redox control mechanisms of tumor cell destruction. The review covers the tumor-intrinsic role of oxidants derived from the reduction of oxygen and nitrogen in the control of tumor cell proliferation as well as the roles of oxidants and antioxidant systems in cancer cell death caused by traditional anticancer weapons (chemotherapeutic agents, radiotherapy, photodynamic therapy). Emphasis is also put on the role of oxidants and redox status in the outcome following interactions between cancer cells, cytotoxic lymphocytes and tumor infiltrating macrophages.

Reactive Oxygen Species and Mitochondrial Dynamics: The Yin and Yang of Mitochondrial Dysfunction and Cancer Progression

Mitochondria are organelles with a highly dynamic ultrastructure maintained by a delicate equilibrium between its fission and fusion rates. Understanding the factors influencing this balance is important as perturbations to mitochondrial dynamics can result in pathological states. As a terminal site of nutrient oxidation for the cell, mitochondrial powerhouses harness energy in the form of ATP in a process driven by the electron transport chain. Contemporaneously, electrons translocated within the electron transport chain undergo spontaneous side reactions with oxygen, giving rise to superoxide and a variety of other downstream reactive oxygen species (ROS). Mitochondrially-derived ROS can mediate redox signaling or, in excess, cause cell injury and even cell death. Recent evidence suggests that mitochondrial ultrastructure is tightly coupled to ROS generation depending on the physiological status of the cell. Yet, the mechanism by which changes in mitochondrial shape modulate mitochondrial function and redox homeostasis is less clear. Aberrant mitochondrial morphology may lead to enhanced ROS formation, which, in turn, may deteriorate mitochondrial health and further exacerbate oxidative stress in a self-perpetuating vicious cycle. Here, we review the latest findings on the intricate relationship between mitochondrial dynamics and ROS production, focusing mainly on its role in malignant disease.

A Mini-Review of Reactive Oxygen Species in Urological Cancer: Correlation with NADPH Oxidases, Angiogenesis, and Apoptosis

Oxidative stress refers to elevated reactive oxygen species (ROS) levels, and NADPH oxidases (NOXs), which are one of the most important sources of ROS. Oxidative stress plays important roles in the etiologies, pathological mechanisms, and treatment strategies of vascular diseases. Additionally, oxidative stress affects mechanisms of carcinogenesis, tumor growth, and prognosis in malignancies. Nearly all solid tumors show stimulation of neo-vascularity, termed angiogenesis, which is closely associated with malignant aggressiveness. Thus, cancers can be seen as a type of vascular disease. Oxidative stress-induced functions are regulated by complex endogenous mechanisms and exogenous factors, such as medication and diet. Although understanding these regulatory mechanisms is important for improving the prognosis of urothelial cancer, it is not sufficient, because there are controversial and conflicting opinions. Therefore, we believe that this knowledge is essential to discuss observations and treatment strategies in urothelial cancer. In this review, we describe the relationships between members of the NOX family and tumorigenesis, tumor growth, and pathological mechanisms in urological cancers including prostate cancer, renal cell carcinoma, and urothelial cancer. In addition, we introduce natural compounds and chemical agents that are associated with ROS-induced angiogenesis or apoptosis.