Activation of NADPH oxidase subunit NCF4 induces ROS-mediated EMT signaling in HeLa cells

Vimentin at the core of wound healing

As a member of the large family of intermediate filaments (IFs), vimentin has emerged as a highly dynamic and versatile cytoskeletal protein involved in many key processes of wound healing. It is well established that vimentin is involved in epithelial-mesenchymal transition (EMT) during wound healing and metastasis, during which epithelial cells acquire more dynamic and motile characteristics. Moreover, vimentin participates in multiple cellular activities supporting growth, proliferation, migration, cell survival, and stress resilience. Here, we explore the role of vimentin at each phase of wound healing, with focus on how it integrates different signaling pathways and protects cells in the fluctuating and challenging environments that characterize a healing tissue.

Thiol-Based Antioxidants and the Epithelial/Mesenchymal Transition in Cancer

Significance: The epithelial/mesenchymal transition (EMT) is commonly associated with tumor metastasis. Oxidative and nitrosative stress is maintained in cancer cells and is involved in the EMT. Cancer cells are endowed with high levels of enzymatic and nonenzymatic antioxidants, which counteract the effects of oxidative and nitrosative stress. Thiol-based antioxidant systems such as the thioredoxin/thioredoxin reductase (Trx/TrxR) and glutathione/glutaredoxin (GSH/Grx) are continually active in cancer cells, while the thioredoxin-interacting protein (Txnip), the negative regulator of the Trx/TrxR system, is downregulated. Recent Advances: Trx/TrxR and GSH/Grx systems play a major role in maintaining EMT signaling and cancer cell progression. Critical Issues: Enhanced stress conditions stimulated in cancer cells inhibit EMT signaling. The elevated expression levels of the Trx/TrxR and GSH/Grx systems in these cells provide the antioxidant protection necessary to guarantee the occurrence of the EMT. Future Directions: Elevation of the intracellular reactive oxygen species and nitric oxide concentrations in cancer cells has been viewed as a promising strategy for elimination of these cells. The development of inhibitors of GSH synthesis and of the Trx/TrxR system together with genetic-based strategies to enhance Txnip levels may provide the necessary means to achieve this goal. Antioxid. Redox Signal. 36, 1037-1050.

Correlation between Oxidative Stress and Transforming Growth Factor-Beta in Cancers

The downregulation of reactive oxygen species (ROS) facilitates precancerous tumor development, even though increasing the level of ROS can promote metastasis. The transforming growth factor-beta (TGF-β) signaling pathway plays an anti-tumorigenic role in the initial stages of cancer development but a pro-tumorigenic role in later stages that fosters cancer metastasis. TGF-β can regulate the production of ROS unambiguously or downregulate antioxidant systems. ROS can influence TGF-β signaling by enhancing its expression and activation. Thus, TGF-β signaling and ROS might significantly coordinate cellular processes that cancer cells employ to expedite their malignancy. In cancer cells, interplay between oxidative stress and TGF-β is critical for tumorigenesis and cancer progression. Thus, both TGF-β and ROS can develop a robust relationship in cancer cells to augment their malignancy. This review focuses on the appropriate interpretation of this crosstalk between TGF-β and oxidative stress in cancer, exposing new potential approaches in cancer biology.

In vitro antimetastatic activity of Momordica balsamina crude acetone extract in HT-29 human colon cancer cells

Plant-derived compounds and/or extracts have proven to be beneficial for the treatment of a broad spectrum of cancers with minimal side effects. In this study, we investigated whether a crude acetone extract of Momordica balsamina (MBE) can interfere with the metastatic ability of HT-29 colorectal cancer (CRC) cells. The phytochemical composition of MBE was determined by ultra-performance liquid chromatography and cytotoxic effects by the MTT and acridine orange/ethidium bromide staining assays. The effect of MBE on the formation of reactive oxygen species was assessed using the DCFH₂ -DA assay. Wound healing assay, transwell cell invasion assay, cell adhesion assay, and the extracellular matrix-cell adhesion array were used to assess the antimetastatic effects of MBE. The effect of MBE on the expression of TNF-α, NF-κB, TIMP-3, MMP-2, and MMP-9 was assessed by western blot analysis. Our results showed that MBE consists of a mixture of compounds without a known anticancer activity in CRC and exhibits cytotoxicity against HT-29 cells. MBE also suppressed reactive oxygen species formation, cell invasion, cell migration, and cell adhesion. The reduction of cell invasion was associated with the downregulation of TNF-α, NF-κB, MMP2, and MMP9 and upregulation of TIMP-3 proteins. We concluded that MBE inhibits the metastatic ability of HT-29 CRC cells in vitro.

Potential Therapeutic Effects of Natural Plant Compounds in Kidney Disease

Background: The blockade of the progression or onset of pathological events is essential for the homeostasis of an organism. Some common pathological mechanisms involving a wide range of diseases are the uncontrolled inflammatory reactions that promote fibrosis, oxidative reactions, and other alterations. Natural plant compounds (NPCs) are bioactive elements obtained from natural sources that can regulate physiological processes. Inflammation is recognized as an important factor in the development and evolution of chronic renal damage. Consequently, any compound able to modulate inflammation or inflammation-related processes can be thought of as a renal protective agent and/or a potential treatment tool for controlling renal damage. The objective of this research was to review the beneficial effects of bioactive natural compounds on kidney damage to reveal their efficacy as demonstrated in clinical studies. Methods: This systematic review is based on relevant studies focused on the impact of NPCs with therapeutic potential for kidney disease treatment in humans. Results: Clinical studies have evaluated NPCs as a different way to treat or prevent renal damage and appear to show some benefits in improving OS, inflammation, and antioxidant capacity, therefore making them promising therapeutic tools to reduce or prevent the onset and progression of KD pathogenesis. Conclusions: This review shows the promising clinical properties of NPC in KD therapy. However, more robust clinical trials are needed to establish their safety and therapeutic effects in the area of renal damage.

Transforming Growth Factor-β and Oxidative Stress in Cancer: A Crosstalk in Driving Tumor Transformation

Simple Summary

Metabolic changes in tumor microenvironment play a critical role in cancer, related to the accumulated alterations in signaling pathways that control cellular metabolism. Cancer metabolic deregulation is related to specific events such as the control of oxidative stress, and in particular the redox imbalance with aberrant oxidant production and/or a deregulation of the efficacy of the antioxidant systems. In cancer cells, different cytokines are involved in the development and/or progression of cancer; among these cytokines, the transforming growth factor β (TGF-β) is central to tumorigenesis and cancer progression. In tumor cells, it has been demonstrated that there is a close correlation between oxidative stress and TGF-β; this crosstalk strongly contributes to tumorigenesis, both in tumor development and in mediating its invasiveness. This review is addressed to better understanding this crosstalk between TGF-β and oxidative stress in cancer cell metabolism, in an attempt to improve the pharmacological and therapeutic approach against cancer.

Abstract

Cancer metabolism involves different changes at a cellular level, and altered metabolic pathways have been demonstrated to be heavily involved in tumorigenesis and invasiveness. A crucial role for oxidative stress in cancer initiation and progression has been demonstrated; redox imbalance, due to aberrant reactive oxygen species (ROS) production or deregulated efficacy of antioxidant systems (superoxide dismutase, catalase, GSH), contributes to tumor initiation and progression of several types of cancer. ROS may modulate cancer cell metabolism by acting as secondary messengers in the signaling pathways (NF-kB, HIF-1α) involved in cellular proliferation and metastasis. It is known that ROS mediate many of the effects of transforming growth factor β (TGF-β), a key cytokine central in tumorigenesis and cancer progression, which in turn can modulate ROS production and the related antioxidant system activity. Thus, ROS synergize with TGF-β in cancer cell metabolism by increasing the redox imbalance in cancer cells and by inducing the epithelial mesenchymal transition (EMT), a crucial event associated with tumor invasiveness and metastases. Taken as a whole, this review is addressed to better understanding this crosstalk between TGF-β and oxidative stress in cancer cell metabolism, in the attempt to improve the pharmacological and therapeutic approach against cancer.

Analysis of mRNA‑lncRNA and mRNA‑lncRNA-pathway co‑expression networks based on WGCNA in developing pediatric sepsis

Pediatric sepsis is a great threat to death worldwide. However, the pathogenesis has not been clearly understood until now in sepsis. This study identified differentially expressed mRNAs and lncRNAs based on Gene Expression Omnibus (GEO) database. And the weighted gene co-expression network analysis (WGCNA) was performed to explore co-expression modules associated with pediatric sepsis. Then, Gene Ontology (GO), KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway, mRNA‑lncRNA and mRNA‑lncRNA-pathway co-expression network analysis was conducted in selected significant module. A total of 1941 mRNAs and 225 lncRNAs were used to conduct WGCNA. And turquoise module was selected as a significant module that was associated with particular traits. The mRNAs functions associated with many vital processes were also shown by GO and KEGG pathway analysis in the turquoise module. Finally, 15 mRNAs (MAPK14, ITGAM, HK3, ALOX5, CR1, HCK, NCF4, PYGL, FLOT1, CARD6, NLRC4, SH3GLB1, PGS1, RAB31, LTB4R) and 4 lncRNAs (GSEC, NONHSAT160878.1, XR_926068.1 and RARA-AS1) were selected as hub genes in mRNA‑lncRNA-Pathway co-expression network. We identified 15 mRNAs and 4 lncRNAs as diagnostic markers, which have potential functions in pediatric sepsis. Our study provides more directions to study the molecular mechanism of pediatric sepsis.Abbreviations: mRNA: messenger RNA; lncRNA: long noncoding RNAs; GEO: Gene Expression Omnibus; WGCNA: weighted gene co-expression network analysis; GO: Gene Ontology; KEGG: Kyoto Encyclopedia of Genes and Genomes; SIRS: systemic inflammatory response syndrome; TOM: topological overlap measure; BP: biological process; MF: molecular function; CC: cellular component; ROC: receiver operating characteristic curve; AUC: area under curve; MAPK14: Mitogen-activated protein kinase 14; ALI: acute lung injury; ITGAM: Integrin subunit alpha M; HK3: Hexokinase 3; LPS: lipopolysaccharide; 5-LO: 5-lipoxygenase; LTs: leukotrienes; LTB4R: leukotriene B4 receptor.

Redox Regulation of the Actin Cytoskeleton in Cell Migration and Adhesion: On the Way to a Spatiotemporal View

The actin cytoskeleton of eukaryotic cells is a dynamic, fibrous network that is regulated by the concerted action of actin-binding proteins (ABPs). In particular, rapid polarization of cells in response to internal and external stimuli is fundamental to cell migration and invasion. Various isoforms of ABPs in different tissues equip cells with variable degrees of migratory and adhesive capacities. In addition, regulation of ABPs by posttranslational modifications (PTM) is pivotal to the rapid responsiveness of cells. In this context, phosphorylation of ABPs and its functional consequences have been studied extensively. However, the study of reduction/oxidation (redox) modifications of oxidation-sensitive cysteine and methionine residues of actin, ABPs, adhesion molecules, and signaling proteins regulating actin cytoskeletal dynamics has only recently emerged as a field. The relevance of such protein oxidations to cellular physiology and pathophysiology has remained largely elusive. Importantly, studying protein oxidation spatiotemporally can provide novel insights into localized redox regulation of cellular functions. In this review, we focus on the redox regulation of the actin cytoskeleton, its challenges, and recently developed tools to study its physiological and pathophysiological consequences.

Adipose-specific BMP and activin membrane-bound inhibitor (BAMBI) deletion promotes adipogenesis by accelerating ROS production

With the improvement of people's living standards, the number of obese patients has also grown rapidly. It is reported that the level of oxidative stress in obese patients has significantly increased, mainly caused by the increase in reactive oxygen species (ROS) levels in adipose tissue. Studies have shown that the use of siRNA to interfere with bone morphogenetic protein and activin membrane-bound inhibitor (BAMBI) expression could promote adipocyte differentiation, and under hypoxic conditions, BAMBI could act as a regulator of HIF1α to regulate the polarity damage of epithelial cells. In view of these results, we speculated that BAMBI may regulate adipogenesis by regulating the level of ROS. In this study, we generated adipose-specific BAMBI knockout mice (BAMBI AKO) and found that compared with control mice, BAMBI AKO mice showed obesity when fed with high-fat diet, accompanied by insulin resistance, glucose intolerance, hypercholesterolemia, and increased inflammation in adipose tissue. Interestingly, adipose-specific deficiency of BAMBI could cause an increase in the expression level of Nox4, thereby promoting ROS production in cytoplasm and mitochondria and the DNA-binding activity of C/EBPβ and ultimately promoting adipogenesis. Consistently, our findings indicated that BAMBI may be a reactive oxygen regulator to affect adipogenesis, thereby controlling obesity and metabolic syndrome.

Airway Redox Homeostasis and Inflammation Gone Awry: From Molecular Pathogenesis to Emerging Therapeutics in Respiratory Pathology

As aerobic organisms, we are continuously and throughout our lifetime subjected to an oxidizing atmosphere and, most often, to environmental threats. The lung is the internal organ most highly exposed to this milieu. Therefore, it has evolved to confront both oxidative stress induced by reactive oxygen species (ROS) and a variety of pollutants, pathogens, and allergens that promote inflammation and can harm the airways to different degrees. Indeed, an excess of ROS, generated intrinsically or from external sources, can imprint direct damage to key structural cell components (nucleic acids, sugars, lipids, and proteins) and indirectly perturb ROS-mediated signaling in lung epithelia, impairing its homeostasis. These early events complemented with efficient recognition of pathogen- or damage-associated recognition patterns by the airway resident cells alert the immune system, which mounts an inflammatory response to remove the hazards, including collateral dead cells and cellular debris, in an attempt to return to homeostatic conditions. Thus, any major or chronic dysregulation of the redox balance, the air-liquid interface, or defects in epithelial proteins impairing mucociliary clearance or other defense systems may lead to airway damage. Here, we review our understanding of the key role of oxidative stress and inflammation in respiratory pathology, and extensively report current and future trends in antioxidant and anti-inflammatory treatments focusing on the following major acute and chronic lung diseases: acute lung injury/respiratory distress syndrome, asthma, chronic obstructive pulmonary disease, pulmonary fibrosis, and cystic fibrosis.

Mannose-binding lectin and associate serine protease complex modulates neutrophil respiratory burst and gene expression in Capra hircus

Neutrophils are an essential cellular component of the innate immune system, responsible for multiple effector mechanisms and aspects of inflammation. Neutrophil priming results in a rapid elevation in antimicrobial activities and can be measured by reactive oxygen species production, bacterial endocytosis, and de-novo synthesis of components such as interleukins. Mannose binding lectin (MBL), a C-type lectin pathogen recognition receptor is associated with immune functions including complement activation, opsonization and modulating immune responses. Whether MBL opsonization of pathogen can induce neutrophil priming has not been studied so far. Hence, studies were performed using MBL and neutrophils of Capra hircus (domestic goat) to evaluate the effects of MBL + MASPs interactions on neutrophil functions. It was found that MBL + MASPs opsonization of zymosan stimulates neutrophil functions including increased oxidative burst, enhanced endocytosis and modulates the expression level of NCF4, XBP1, CCL2, and CR1 genes. The results suggest that MBL-MASP complex can regulate neutrophil functioning.

Redox Regulation of NOX Isoforms on FAK(Y397)/SRC(Y416) Phosphorylation Driven Epithelial-to-Mesenchymal Transition in Malignant Cervical Epithelial Cells

Epithelial-to-mesenchymal transition (EMT) promulgates epithelial cell associated disease-defining characteristics in tumorigenesis and organ fibrosis. Growth factors such as epidermal growth factor and fibroblast growth factor in addition to cytokines such as transforming growth factor-β1 (TGF-β1) is said to play a prominent role in remodeling related pathological events of cancer progression such as invasion, metastasis, apoptosis, EMT, etc. through redox related cellular secondary messengers, in particular the reactive oxygen species (ROS). However, the signaling cascade underlying the redox mechanism and thereby the progression of EMT remains largely unknown. In this study, upon TGF-β1 treatment, we observed an induction in NOX isoforms-NOX2 and NOX4-that have time (early and late) and cellular localization (nucleus and autophagosome co-localized) dependent effects in mediating EMT associated cell proliferation and migration through activation of the focal adhesion kinase (FAK)/SRC pathway in HeLa, human cervical cancer cells. Upon silencing NOX2/4 gene expression and using the SRC inhibitor (AZD0530), progression of TGF-β1 induced EMT related cellular remodeling, extra cellular matrix (ECM) production, cell migration and invasion, got significantly reverted. Together, these results indicate that NOX2 and NOX4 play important, albeit distinct, roles in the activation of cytokine mediated EMT and its associated processes via tyrosine phosphorylation of the FAK/SRC pathway.

Smart Sorting of Tumor Phenotype with Versatile Fluorescent Ag Nanoclusters by Sensing Specific Reactive Oxygen Species

Reactive oxygen species (ROS) play a crucial role in cancer formation and development, especially cancer metastasis. However, lack of a precise tool, which could accurately distinguish specific types of ROS, restricts an in-depth study of ROS in cancer development and progression. Herein, we designed smart and versatile fluorescent Ag nanoclusters (AgNCs) for sensitive and selective detection of different species of ROS in cells and tissues.

Methods: Firstly, dual-emission fluorescent AgNCs was synthesized by using bovine serum albumin (BSA) to sense different types of ROS (H₂O₂, O2•-, •OH). The responsiveness of the AgNCs to different species of ROS was explored by fluorescence spectrum, hydrodynamic diameter, and so on. Furthermore, dual-emission fluorescent AgNCs was used to sense ROS in tumor with different degrees of differentiation. Finally, the relationship between specific types of ROS and tumor cell invasion was explored by cell migration ability and the expression of cell adhesion and EMT markers.

Results: This dual-emission fluorescent AgNCs possessed an excellent ability to sensitively and selectively distinguish highly reactive oxygen species (hROS, including O₂•^-and •OH) from moderate reactive oxygen species (the form of H₂O₂), and exhibited no fluoresence and green fluorescence, respectively. The emission of AgNCs is effective in detecting cellular and tissular ROS. When cultured with AgNCs, malignant tumor cells exhibit non-fluorescence, while the benign tumor emits green and reduced red light and the normal cells appear in weak green and bright red fluorescence. We further verified that not just H₂O₂ but specific species of ROS (O₂•^-and •OH) were involved in cell invasion and malignant transformation. Our study warrants further research on the role of ROS in physiological and pathophysiological processes.

Conclusion: Taken together, AgNCs would be a promising approach for sensing ROS, and offer an intelligent tool to detect different kinds of ROS in tumors.

Targeting the functional interplay between endoplasmic reticulum oxidoreductin-1α and protein disulfide isomerase suppresses the progression of cervical cancer

BACKGROUND

Endoplasmic reticulum (ER) oxidoreductin-1α (Ero1α) and protein disulfide isomerase (PDI) constitute the pivotal pathway of oxidative protein folding, and are highly expressed in many cancers. However, whether targeting the functional interplay between Ero1α and PDI could be a new approach for cancer therapy remains unknown.

METHODS

We performed wound healing assays, transwell migration and invasion assays and xenograft assays to assess cell migration, invasion and tumorigenesis; gel filtration chromatography, oxygen consumption assay and in cells folding assays were used to detect Ero1α-PDI interaction and Ero1α oxidase activity.

FINDINGS

Here, we report that elevated expression of Ero1α is correlated with poor prognosis in human cervical cancer. Knockout of ERO1A decreases the growth, migration and tumorigenesis of cervical cancer cells, through downregulation of the H2O2-correlated epithelial-mesenchymal transition. We identify that the conserved valine (Val) 101 of Ero1α is critical for Ero1α-PDI complex formation and Ero1α oxidase activity. Val101 of Ero1α is specifically involved in the recognition of PDI catalytic domain. Mutation of Val101 results in a reduced ER, retarded oxidative protein folding and decreased H2O2 levels in the ER of cervical cancer cells and further impairs cell migration, invasion, and tumor growth.

INTERPRETATION

Our study identifies the critical residue of Ero1α for recognizing PDI, which underlines the molecular mechanism of oxidative protein folding for tumorigenesis and provides a proof-of-concept for cancer therapy by targeting Ero1α-PDI interaction. FUND: This work was supported by National Key R&D Program of China, National Natural Science Foundation of China, and Youth Innovation Promotion Association, CAS.

Oncogenic Metabolism Acts as a Prerequisite Step for Induction of Cancer Metastasis and Cancer Stem Cell Phenotype

Metastasis is a major obstacle to the efficient and successful treatment of cancer. Initiation of metastasis requires epithelial-mesenchymal transition (EMT) that is regulated by several transcription factors, including Snail and ZEB1/2. EMT is closely linked to the acquisition of cancer stem cell (CSC) properties and chemoresistance, which contribute to tumor malignancy. Tumor suppressor p53 inhibits EMT and metastasis by negatively regulating several EMT-inducing transcription factors and regulatory molecules; thus, its inhibition is crucial in EMT, invasion, metastasis, and stemness. Metabolic alterations are another hallmark of cancer. Most cancer cells are more dependent on glycolysis than on mitochondrial oxidative phosphorylation for their energy production, even in the presence of oxygen. Cancer cells enhance other oncogenic metabolic pathways, such as glutamine metabolism, pentose phosphate pathway, and the synthesis of fatty acids and cholesterol. Metabolic reprogramming in cancer is regulated by the activation of oncogenes or loss of tumor suppressors that contribute to tumor progression. Oncogenic metabolism has been recently linked closely with the induction of EMT or CSC phenotypes by the induction of several metabolic enzyme genes. In addition, several transcription factors and molecules involved in EMT or CSCs, including Snail, Dlx-2, HIF-1α, STAT3, TGF-β, Wnt, and Akt, regulate oncogenic metabolism. Moreover, p53 induces metabolic change by directly regulating several metabolic enzymes. The collective data indicate the importance of oncogenic metabolism in the regulation of EMT, cell invasion and metastasis, and adoption of the CSC phenotype, which all contribute to malignant transformation and tumor development. In this review, we highlight the oncogenic metabolism as a key regulator of EMT and CSC, which is related with tumor progression involving metastasis and chemoresistance. Targeting oncometabolism might be a promising strategy for the development of effective anticancer therapy.

MicroRNAs and signaling networks involved in epithelial-mesenchymal transition

Epithelial-mesenchymal transition (EMT) is a phenomenon in which epithelial cells lose their cell-to-cell connection and are detached from the base membrane. EMT is fundamental for many biological processes such as embryonic development and neurogenesis. It also plays a significant role in cancer progression and metastasis. EMT regulation occurs through a sophisticated network of transcription regulations that include many signaling pathways. The exact mechanism of cancer gene regulation has not been understood yet. However, it is interesting to study the role of microRNAs and epigenetics mechanism in the cancer development. In this review, the transcription regulation of EMT and the analysis of possible overlap between microRNAs and their targets which are involved in the cancer development are scrutinized.

NADPH oxidase 5 promotes proliferation and fibrosis in human hepatic stellate cells

NADPH oxidase (Nox) variants Nox1, Nox2 and Nox4 are implicated in the progression of liver fibrosis. However, the role of Nox5 is not yet known, mainly due to the lack of this enzyme in rat and mouse genomes. Here we describe the expression and functional relevance of Nox5 in the human cell line of hepatic stellate cells (HSC) LX-2. Under basal conditions, three long (Nox5-L: Nox5α, -β, and -δ) and a short (Nox5-S or Nox5ε) splice variants were detected, which were silenced with specific siRNAs for Nox5. The most abundant isoform was Nox5-S, accounting for more than 90% of Nox5 protein. Overexpression of Nox5β generated reactive oxygen species (ROS) in the presence of calcium, as judged by the production of hydrogen peroxide, L-012 luminescence and cytochrome c reduction. Nox5ε did not generated ROS under these conditions, and a reduced ROS production was observed when co-expressed with Nox5β. In contrast, dihydroethidium oxidation was increased by Nox5β or Nox5ε, suggesting that Nox5ε induced intracellular oxidative stress by an unknown mechanism. Functional studies showed that both Nox5β and Nox5ε stimulated the proliferation of LX-2 cells and the collagen type I levels, while Nox5 siRNAs inhibited these effects. Interestingly, TGF-β and angiotensin II upregulated Nox5 expression, which was reduced in cells pre-incubated with catalase. Further studies silencing Nox5 in TGF-β-treated cells resulted in a reduction of collagen levels via p38 MAPK. Collectively, these results show for the first time that Nox5 can play a relevant role in the proliferation and fibrosis on human HSC.

TGF-β induced epithelial-mesenchymal transition in an advanced cervical tumor model by 3D printing

An advanced in vitro cervical tumor model was established by 3D printing to study the epithelial-to-mesenchymal transition (EMT), which is a very important stage of dissemination of carcinoma leading to metastatic tumors. A HeLa/hydrogel grid construct composed of gelatin, alginate, Matrigel and HeLa cells was fabricated by forced extrusion in a layer-by-layer fashion. HeLa cells rapidly proliferated, formed spheroids and presented tumorigenic characteristic in the 3D-printed structure. With the supplement of TGF-β, aggregated HeLa cells started to disintegrate, and some of them changed into fibroblast-like spindle morphology, which indicated that EMT was induced. The down-regulation of epithelial marker E-cadherin, and up-regulation of mesenchymal markers such as snail, vimentin and N-cadherin were all observed in the 3D-printed model, and performed differently in 3D and 2D models. The TGF-β induced EMT was inhibited by the treatment of disulfiram and EMT pathway inhibitor C19 in a dose dependent manner, showing great potential for future studies of a therapeutic program towards cervical tumor metastasis.

How the Warburg effect supports aggressiveness and drug resistance of cancer cells?

Cancer cells employ both conventional oxidative metabolism and glycolytic anaerobic metabolism. However, their proliferation is marked by a shift towards increasing glycolytic metabolism even in the presence of O₂ (Warburg effect). HIF1, a major hypoxia induced transcription factor, promotes a dissociation between glycolysis and the tricarboxylic acid cycle, a process limiting the efficient production of ATP and citrate which otherwise would arrest glycolysis. The Warburg effect also favors an intracellular alkaline pH which is a driving force in many aspects of cancer cell proliferation (enhancement of glycolysis and cell cycle progression) and of cancer aggressiveness (resistance to various processes including hypoxia, apoptosis, cytotoxic drugs and immune response). This metabolism leads to epigenetic and genetic alterations with the occurrence of multiple new cell phenotypes which enhance cancer cell growth and aggressiveness. In depth understanding of these metabolic changes in cancer cells may lead to the development of novel therapeutic strategies, which when combined with existing cancer treatments, might improve their effectiveness and/or overcome chemoresistance.

Residual Ammonium Persulfate in Nanoparticles Has Cytotoxic Effects on Cells through Epithelial-Mesenchymal Transition

Ammonium persulfate (APS), a low molecular weight chemical compound with strong oxidizing properties, should to be totally removed during preparation of nanomaterials due to its cytotoxicity. APS exerts its oxidative stress effects mainly on cell membrane, but its intracellular influence remains unclear. Here, we designed a facile negatively-charged carboxylic gelatin-methyacrylate (carbox-GelMA) nanoparticle (NP) as a cargo-carrier through the catalytic and oxidizing action of APS in W/O system. The formed APS-loaded carbox-GelMA NPs (APS/NPs) were transported into the lysosome in MCF-7 breast cancer cells. The intracellular APS/NPs produced a high level of oxidative stress in lysosome and induced epithelial-mesenchymal transition (EMT). Consequently, the MCF-7 cells challenged with APS/NPs had a strong metastatic and invasive capability in vitro and in vivo. This study highlights that a facile APS-loaded nanocarrier has cyctotoxicity on cells through EMT. Unexpectedly, we found a novel pathway inducing EMT via lysosomal oxidative stress.

CYT-Rx20 Inhibits Cervical Cancer Cell Growth and Migration Through Oxidative Stress-Induced DNA Damage, Cell Apoptosis, and Epithelial-to-Mesenchymal Transition Inhibition

OBJECTIVE

The β-nitrostyrene family has been reported to possess anticancer properties. However, the anticancer activity of β-nitrostyrenes on cervical cancer cells and the underlying mechanisms involved remain unexplored. In this study, a β-nitrostyrene derivative CYT-Rx20 (3'-hydroxy-4'-methoxy-β-methyl-β-nitrostyrene) was synthesized, and its anticancer activity on cervical cancer cells and the mechanisms involved were investigated.

METHODS

The effect of CYT-Rx20 on human cervical cancer cell growth was evaluated using cell viability assay. Reactive oxygen species (ROS) generation and annexin V staining were detected by flow cytometry. The protein expression levels of cleaved caspase-3, cleaved caspase-9, cleaved poly (ADPribose) polymerase, γH2AX, β-catenin, Vimentin, and Twist were measured by Western blotting. DNA double-strand breaks were determined by γ-H2AX foci formation and neutral comet assay. Migration assay was used to determine cancer cell migration. Nude mice xenograft was used to investigate the antitumor effects of CYT-Rx20 in vivo.

RESULTS

CYT-Rx20 induced cytotoxicity in cervical cancer cells by promoting cell apoptosis via ROS generation and DNA damage. CYT-Rx20-induced cell apoptosis, ROS generation, and DNA damage were reversed by thiol antioxidants. In addition, CYT-Rx20 inhibited cervical cancer cell migration by regulating the expression of epithelial-to-mesenchymal transition markers. In nude mice, CYT-Rx20 inhibited cervical tumor growth accompanied by increased expression of DNA damage marker γH2AX and decreased expression of mesenchymal markers β-catenin and Twist.

CONCLUSIONS

CYT-Rx20 inhibits cervical cancer cells in vitro and in vivo and has the potential to be further developed into an anti-cervical cancer drug clinically.

Suberoylanilide hydroxamic acid induces thioredoxin1-mediated apoptosis in lung cancer cells via up-regulation of miR-129-5p

Histone deacetylase (HDAC) inhibitors, especially suberoylanilide hydroxamic acid (SAHA) induce apoptosis in various cancer cells. Here, we investigated the effect of SAHA on apoptosis in lung cancer cells and addressed the role of reactive oxygen species (ROS), glutathione (GSH), and thioredoxin1 (Trx1) levels in this process. We also identified the miRNAs that down-regulate Trx1 expression at RNA level and thereby influence apoptotic cell death of SAHA increased intracellular ROS levels and promoted apoptotic cell death in cancerous cells but not in non-cancerous normal lung cells. Likewise, SAHA induced GSH depletion specifically in cancerous cells. While N-acetyl cysteine (NAC) reduced ROS level and reversed the effect of SAHA on cell death, L-buthionine sulfoximine (BSO) further enhanced GSH depletion, and promoted cell death. SAHA decreased the mRNA and protein levels of Trx1 in lung cancer cells. Knockdown/suppression of Trx1 intensified apoptosis in SAHA-treated lung cancer cells whereas overexpression of Trx1 prevented the cell death in these cells. SAHA up-regulated the level of miR-129-5p, which binds to 3' untranslated region (3'UTR) of Trx1 and down-regulates Trx1 expression. Down-regulation of Trx1 led to activation of apoptosis-signal regulating kinase (ASK), which induced apoptotic cell death by triggering ASK-JNK or ASK-p38 kinase pathway. In conclusion, changes in ROS and GSH levels in SAHA-treated lung cancer cells partially co-related with cell death. SAHA induced apoptosis via the down-regulation of Trx1, which was regulated by miR-129-5p.

ABCG2 and NCF4 polymorphisms are associated with clinical outcomes in diffuse large B-cell lymphoma patients treated with R-CHOP

The impact of pharmacogenetics on predicting survival in diffuse large B-cell lymphoma (DLBCL) remains unclear. We tested 337 DLBCL patients treated with rituximab-cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) for 9 single nucleotide polymorphisms from 6 genes (CD20, FCGR2A, NAD(P)H, ABCC2, ABCG2 and CYP3A5). Patients who carried the NCF4 rs1883112 GG genotype showed significantly shorter progression-free survival (PFS) (P = 0.023) and event-free survival (EFS) (P < 0.001) comparing with A allele. A significantly shortened PFS (P = 0.013) and EFS (P = 0.002) was also observed in the patients with ABCG2 rs2231137 GG genotype. Furthermore, the elder (> 60 years old) or male patients with ABCG2 rs2231137 GG genotype had poorer PFS and EFS than A allele. Moreover, CD20 rs2070770 CC and RAC2 rs13058338 AT genotypes were independent predictors of chemotherapy-induced toxicity. Cox proportional hazards analyses demonstrated that the GG genotype of ABCG2 rs2231137 and NCF4 rs1883112 were risk factors in DLBCL patients. In conclusion, the identified polymorphisms provide guide for the identification of DLBCL patients who are likely to benefit from chemotherapy.

Melatonin attenuates TGFβ1-induced epithelial-mesenchymal transition in lung alveolar epithelial cells

Idiopathic pulmonary fibrosis (IPF) is the most common interstitial lung disease. However, the pathogenesis remains to be fully elucidated. Melatonin is secreted by the pineal gland, it has a strong antioxidant effect, and exerts an anti-fibrosis effect. Whether melatonin attenuates pulm -onary fibrosis by inhibiting epithelial‑mesenchymal transition (EMT) requires further research. The present study aimed to investigate whether melatonin prevents transforming growth factor‑β1 (TGF‑β1)‑induced EMT and underlying signaling pathways using reverse transcription‑quantitative polymerase chain reaction, western blot analysis and immunofluorescence. The results demonstrated that melatonin inhibits EMT in A549 cells, and the Wnt/β‑catenin and Smad2/3 signaling pathways are involved in the EMT of the A549 cell line as they were suppressed by melatonin. The present study indicates that melatonin inhibited TGFβ1‑induced epithelial‑mesenchymal transition in the A549 cell line and may potentially be useful in the treatment of IPF.

Gemcitabine treatment promotes pancreatic cancer stemness through the Nox/ROS/NF-κB/STAT3 signaling cascade

Gemcitabine, the standard chemotherapy drug for advanced pancreatic cancer, has shown limited benefits because of profound chemoresistance. However, the mechanism involved remains unclear. Cancer stem cells exhibit great tumorigenicity and are closely correlated with drug resistance and tumor relapse. In this study, we demonstrated that certain doses of gemcitabine increased the ratios of CD24⁺ and CD133⁺ cells and the expression of stemness-associated genes such as Bmi1, Nanog, and Sox2. The enhancement of stemness after gemcitabine treatment was accompanied by increased cell migration, chemoresistance, and tumorigenesis. Moreover, we found that gemcitabine promoted the binding of phosphorylated STAT3 to the promoter of Bmi1, Nanog, and Sox2 genes. Furthermore, inhibition of STAT3 partially reversed gemcitabine-induced sphere formation, migration, chemoresistance, and tumor relapse. We also demonstrated that the activation of STAT3 and gemcitabine-enhanced stemness was NADPH oxidase (Nox)-generated, ROS-dependent, and NF-κB partially mediated the process. Together, our results suggest a pivotal role of pancreatic cancer stem cells in developing chemoresistance toward gemcitabine treatment through the Nox/ROS/NF-κB/STAT3 signaling pathway. These findings will provide new insight for identifying potential targets that can be used to sensitize pancreatic cancer cells to chemotherapy.

Effects of Chrysotile Exposure in Human Bronchial Epithelial Cells: Insights into the Pathogenic Mechanisms of Asbestos-Related Diseases

BACKGROUND

Chrysotile asbestos accounts for > 90% of the asbestos used worldwide, and exposure is associated with asbestosis (asbestos-related fibrosis) and other malignancies; however, the molecular mechanisms involved are not fully understood. A common pathogenic mechanism for these malignancies is represented by epithelial-mesenchymal transition (EMT), through which epithelial cells undergo a morphological transformation to assume a mesenchymal phenotype. In the present work, we propose that chrysotile asbestos induces EMT through a mechanism involving a signaling pathway mediated by tranforming growth factor beta (TGF-β).

OBJECTIVES

We investigated the role of chrysotile asbestos in inducing EMT in order to elucidate the molecular mechanisms involved in this event.

METHODS

Human bronchial epithelial cells (BEAS-2B) were incubated with 1 μg/cm2 chrysotile asbestos for ≤ 72 hr, and several markers of EMT were investigated. Experiments with specific inhibitors for TGF-β, glycogen synthase kinase-3β (GSK-3β), and Akt were performed to confirm their involvement in asbestos-induced EMT. Real-time polymerase chain reaction (PCR), Western blotting, and gelatin zymography were performed to detect mRNA and protein level changes for these markers.

RESULTS

Chrysotile asbestos activated a TGF-β-mediated signaling pathway, implicating the contributions of Akt, GSK-3β, and SNAIL-1. The activation of this pathway in BEAS-2B cells was associated with a decrease in epithelial markers (E-cadherin and β-catenin) and an increase in mesenchymal markers (α-smooth muscle actin, vimentin, metalloproteinases, and fibronectin).

CONCLUSIONS

Our findings suggest that chrysotile asbestos induces EMT, a common event in asbestos-related diseases, at least in part by eliciting the TGF-β-mediated Akt/GSK-3β/SNAIL-1 pathway.

CITATION

Gulino GR, Polimeni M, Prato M, Gazzano E, Kopecka J, Colombatto S, Ghigo D, Aldieri E. 2016. Effects of chrysotile exposure in human bronchial epithelial cells: insights into the pathogenic mechanisms of asbestos-related diseases. Environ Health Perspect 124:776-784; http://dx.doi.org/10.1289/ehp.1409627.

Transforming growth factor-β1 in carcinogenesis, progression, and therapy in cervical cancer

Transforming growth factor β1 (TGF-β1) is a multifunctional cytokine that plays important roles in cervical tumor formation, invasion, progression, and metastasis. TGF-β1 functions as a tumor inhibitor in precancerous lesions and early stage cancers of cervix whereas as a tumor promoter in later stage. This switch from a tumor inhibitor to a tumor promoter might be due to various alterations in TGF-β signaling pathway, such as mutations or loss of expression of TGF-β receptors and SMAD proteins. Additionally, the oncoproteins of human papillomaviruses have been shown to stimulate TGF-β1 expression, which in turn suppresses host immune surveillance. Thus, in addition to driving tumor cell migration and metastasis, TGF-β1 is believed to play a key role in promoting human papillomavirus infection by weakening host immune defense. In this article, we will discuss the role of TGF-β1 in the expression, carcinogenesis, progression, and therapy in cervical cancers. A better understanding of this cytokine in cervical carcinogenesis is essential for critical evaluation of this cytokine as a potential prognostic marker and therapeutic target.

Epithelial-mesenchymal transition: a new target in anticancer drug discovery

The conversion of cells with an epithelial phenotype into cells with a mesenchymal phenotype, referred to as epithelial-mesenchymal transition, is a critical process for embryonic development that also occurs in adult life, particularly during tumour progression. Tumour cells undergoing epithelial-mesenchymal transition acquire the capacity to disarm the body's antitumour defences, resist apoptosis and anticancer drugs, disseminate throughout the organism, and act as a reservoir that replenishes and expands the tumour cell population. Epithelial-mesenchymal transition is therefore becoming a target of prime interest for anticancer therapy. Here, we discuss the screening and classification of compounds that affect epithelial-mesenchymal transition, highlight some compounds of particular interest, and address issues related to their clinical application.

Role of an SNP in Alternative Splicing of Bovine NCF4 and Mastitis Susceptibility

Neutrophil cytosolic factor 4 (NCF4) is component of the nicotinamide dinucleotide phosphate oxidase complex, a key factor in biochemical pathways and innate immune responses. In this study, splice variants and functional single-nucleotide polymorphism (SNP) of NCF4 were identified to determine the variability and association of the gene with susceptibility to bovine mastitis characterized by inflammation. A novel splice variant, designated as NCF4-TV and characterized by the retention of a 48 bp sequence in intron 9, was detected in the mammary gland tissues of infected cows. The expression of the NCF4-reference main transcript in the mastitic mammary tissues was higher than that in normal tissues. A novel SNP, g.18174 A>G, was also found in the retained 48 bp region of intron 9. To determine whether NCF4-TV could be due to the g.18174 A>G mutation, we constructed two mini-gene expression vectors with the wild-type or mutant NCF4 g.18174 A>G fragment. The vectors were then transiently transfected into 293T cells, and alternative splicing of NCF4 was analyzed by reverse transcription-PCR and sequencing. Mini-gene splicing assay demonstrated that the aberrantly spliced NCF4-TV with 48 bp retained fragment in intron 9 could be due to g.18174 A>G, which was associated with milk somatic count score and increased risk of mastitis infection in cows. NCF4 expression was also regulated by alternative splicing. This study proposes that NCF4 splice variants generated by functional SNP are important risk factors for mastitis susceptibility in dairy cows.

Reciprocal regulation of TGF-β and reactive oxygen species: A perverse cycle for fibrosis

Transforming growth factor beta (TGF-β) is the most potent pro-fibrogenic cytokine and its expression is increased in almost all of fibrotic diseases. Although signaling through Smad pathway is believed to play a central role in TGF-β's fibrogenesis, emerging evidence indicates that reactive oxygen species (ROS) modulate TGF-β's signaling through different pathways including Smad pathway. TGF-β1 increases ROS production and suppresses antioxidant enzymes, leading to a redox imbalance. ROS, in turn, induce/activate TGF-β1 and mediate many of TGF-β's fibrogenic effects, forming a vicious cycle (see graphic flow chart on the right). Here, we review the current knowledge on the feed-forward mechanisms between TGF-β1 and ROS in the development of fibrosis. Therapeutics targeting TGF-β-induced and ROS-dependent cellular signaling represents a novel approach in the treatment of fibrotic disorders.

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TGF-β1 is the most potent ubiquitous profibrogenic cytokine.

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TGF- β 1 induces redox imbalance by ↑ ROS production and ↓ anti-oxidant defense system

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Redox imbalance, in turn, activates latent TGF-β1 and induces TGF-β1 expression.

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Redox imbalance also mediates many of TGF-β1’s profibrogenic effects

Transforming Growth Factor-Beta and Oxidative Stress Interplay: Implications in Tumorigenesis and Cancer Progression

Transforming growth factor-beta (TGF-β) and oxidative stress/Reactive Oxygen Species (ROS) both have pivotal roles in health and disease. In this review we are analyzing the interplay between TGF-β and ROS in tumorigenesis and cancer progression. They have contradictory roles in cancer progression since both can have antitumor effects, through the induction of cell death, senescence and cell cycle arrest, and protumor effects by contributing to cancer cell spreading, proliferation, survival, and metastasis. TGF-β can control ROS production directly or by downregulating antioxidative systems. Meanwhile, ROS can influence TGF-β signaling and increase its expression as well as its activation from the latent complex. This way, both are building a strong interplay which can be taken as an advantage by cancer cells in order to increment their malignancy. In addition, both TGF-β and ROS are able to induce cell senescence, which in one way protects damaged cells from neoplastic transformation but also may collaborate in cancer progression. The mutual collaboration of TGF-β and ROS in tumorigenesis is highly complex, and, due to their differential roles in tumor progression, careful consideration should be taken when thinking of combinatorial targeting in cancer therapies.

Antioxidant Mechanisms and ROS-Related MicroRNAs in Cancer Stem Cells

Increasing evidence indicates that most of the tumors are sustained by a distinct population of cancer stem cells (CSCs), which are responsible for growth, metastasis, invasion, and recurrence. CSCs are typically characterized by self-renewal, the key biological process allowing continuous tumor proliferation, as well as by differentiation potential, which leads to the formation of the bulk of the tumor mass. CSCs have several advantages over the differentiated cancer cell populations, including the resistance to radio- and chemotherapy, and their gene-expression programs have been shown to correlate with poor clinical outcome, further supporting the relevance of stemness properties in cancer. The observation that CSCs possess enhanced mechanisms of protection from reactive oxygen species (ROS) induced stress and a different metabolism from the differentiated part of the tumor has paved the way to develop drugs targeting CSC specific signaling. In this review, we describe the role of ROS and of ROS-related microRNAs in the establishment and maintenance of self-renewal and differentiation capacities of CSCs.

Involvement of ROS-alpha v beta 3 integrin-FAK/Pyk2 in the inhibitory effect of melatonin on U251 glioma cell migration and invasion under hypoxia

BACKGROUND

Melatonin, a well-known antioxidant, has been shown to possess anti-invasive properties for glioma. However, little is known about the effect of melatonin on glioma cell migration and invasion under hypoxia, which is a crucial microenvironment for tumor progress. In addition, focal adhesion kinase (FAK) and proline-rich tyrosine kinase 2 (Pyk2) are closely associated with cell migration and invasion. Therefore, we investigated the possible role of these kinases and its related signaling in the regulation of human U251 glioma cells behavior by melatonin under hypoxia.

METHODS

The abilities of migration and invasion of U251 glioma cells were determined by wound healing and transwell assay in vitro. The intracellular production of reactive oxygen species (ROS) was measured by using the fluorescent probe 6-carboxy-2', 7'-dichorodihydrofluorescein diacetate (DCFH-DA). Immunofluorescence experiments and western blotting analysis were used to detect the expression level of protein. Small interfering RNAs (siRNA) was used to silence specific gene expression.

RESULTS

The pharmacologic concentration (1 mM) of melatonin significantly inhibited the migration and invasion of human U251 glioma cells under hypoxia. The inhibitory effect of melatonin was accompanied with the reduced phosphorylation of FAK and Pyk2, and decreased expression of alpha v beta 3 (αvβ3) integrin. Additionally, inhibition of αvβ3 integrin by siRNA reduced the phosphorylation of FAK/Pyk2 and demonstrated the similar anti-tumor effects as melatonin, suggesting the involvement of αvβ3 integrin- FAK/Pyk2 pathway in the anti-migratory and anti-invasive effect of melatonin. It was also found that melatonin treatment decreased the ROS levels in U251 glioma cells cultured under hypoxia. ROS inhibitor apocynin not only inhibited αvβ3 integrin expression and the phosphorylation levels of FAK and Pyk2, but also suppressed the migratory and invasive capacity of U251 glioma cells under hypoxia.

CONCLUSIONS

These results suggest that melatonin exerts anti-migratory and anti-invasive effects on glioma cells in response to hypoxia via ROS-αvβ3 integrin-FAK/Pyk2 signaling pathways. This provides evidence that melatonin may be a potential therapeutic molecule targeting the hypoxic microenvironment of glioma.

FOXP1 inhibits cell growth and attenuates tumorigenicity of neuroblastoma

BACKGROUND

Segmental genomic copy number alterations, such as loss of 11q or 3p and gain of 17q, are well established markers of poor outcome in neuroblastoma, and have been suggested to comprise tumor suppressor genes or oncogenes, respectively. The gene forkhead box P1 (FOXP1) maps to chromosome 3p14.1, a tumor suppressor locus deleted in many human cancers including neuroblastoma. FoxP1 belongs to a family of winged-helix transcription factors that are involved in processes of cellular proliferation, differentiation and neoplastic transformation.

METHODS

Microarray expression profiles of 476 neuroblastoma specimens were generated and genes differentially expressed between favorable and unfavorable neuroblastoma were identified. FOXP1 expression was correlated to clinical markers and patient outcome. To determine whether hypermethylation is involved in silencing of FOXP1, methylation analysis of the 5' region of FOXP1 in 47 neuroblastomas was performed. Furthermore, FOXP1 was re-expressed in three neuroblastoma cell lines to study the effect of FOXP1 on growth characteristics of neuroblastoma cells.

RESULTS

Low expression of FOXP1 is associated with markers of unfavorable prognosis like stage 4, age >18 months and MYCN amplification and unfavorable gene expression-based classification (P < 0.001 each). Moreover, FOXP1 expression predicts patient outcome accurately and independently from well-established prognostic markers. Array-based CGH analysis of 159 neuroblastomas revealed that heterozygous loss of the FOXP1 locus was a rare event (n = 4), but if present, was associated with low FOXP1 expression. By contrast, DNA methylation analysis in 47 neuroblastomas indicated that hypermethylation is not regularly involved in FOXP1 gene silencing. Re-expression of FoxP1 significantly impaired cell proliferation, viability and colony formation in soft agar. Furthermore, induction of FOXP1 expression led to cell cycle arrest and apoptotic cell death of neuroblastoma cells.

CONCLUSIONS

Our results suggest that down-regulation of FOXP1 expression is a common event in high-risk neuroblastoma pathogenesis and may contribute to tumor progression and unfavorable patient outcome.

Antioxidants maintain E-cadherin levels to limit Drosophila prohemocyte differentiation

Mitochondrial reactive oxygen species (ROS) regulate a variety of biological processes by networking with signal transduction pathways to maintain homeostasis and support adaptation to stress. In this capacity, ROS have been shown to promote the differentiation of progenitor cells, including mammalian embryonic and hematopoietic stem cells and Drosophila hematopoietic progenitors (prohemocytes). However, many questions remain about how ROS alter the regulatory machinery to promote progenitor differentiation. Here, we provide evidence for the hypothesis that ROS reduce E-cadherin levels to promote Drosophila prohemocyte differentiation. Specifically, we show that knockdown of the antioxidants, Superoxide dismutatase 2 and Catalase reduce E-cadherin protein levels prior to the loss of Odd-skipped-expressing prohemocytes. Additionally, over-expression of E-cadherin limits prohemocyte differentiation resulting from paraquat-induced oxidative stress. Furthermore, two established targets of ROS, Enhancer of Polycomb and FOS, control the level of E-cadherin protein expression. Finally, we show that knockdown of either Superoxide dismutatase 2 or Catalase leads to an increase in the E-cadherin repressor, Serpent. As a result, antioxidants and targets of ROS can control E-cadherin protein levels, and over-expression of E-cadherin can ameliorate the prohemocyte response to oxidative stress. Collectively, these data strongly suggest that ROS promote differentiation by reducing E-cadherin levels. In mammalian systems, ROS promote embryonic stem cell differentiation, whereas E-cadherin blocks differentiation. However, it is not known if elevated ROS reduce E-cadherin to promote embryonic stem cell differentiation. Thus, our findings may have identified an important mechanism by which ROS promote stem/progenitor cell differentiation.