Superoxide dismutase promotes the epithelial-mesenchymal transition of pancreatic cancer cells via activation of the H2O2/ERK/NF-κB axis

The Role of Oxidative Stress in Tumorigenesis and Progression

Oxidative stress refers to the imbalance between the production of reactive oxygen species (ROS) and the endogenous antioxidant defense system. Its involvement in cell senescence, apoptosis, and series diseases has been demonstrated. Advances in carcinogenic research have revealed oxidative stress as a pivotal pathophysiological pathway in tumorigenesis and to be involved in lung cancer, glioma, hepatocellular carcinoma, leukemia, and so on. This review combs the effects of oxidative stress on tumorigenesis on each phase and cell fate determination, and three features are discussed. Oxidative stress takes part in the processes ranging from tumorigenesis to tumor death via series pathways and processes like mitochondrial stress, endoplasmic reticulum stress, and ferroptosis. It can affect cell fate by engaging in the complex relationships between senescence, death, and cancer. The influence of oxidative stress on tumorigenesis and progression is a multi-stage interlaced process that includes two aspects of promotion and inhibition, with mitochondria as the core of regulation. A deeper and more comprehensive understanding of the effects of oxidative stress on tumorigenesis is conducive to exploring more tumor therapies.

Determination and characterization of molecular heterogeneity and precision medicine strategies of patients with pancreatic cancer and pancreatic neuroendocrine tumor based on oxidative stress and mitochondrial dysfunction-related genes

Background

Mitochondria are significant both for cellular energy production and reactive oxygen/nitrogen species formation. However, the significant functions of mitochondrial genes related to oxidative stress (MTGs-OS) in pancreatic cancer (PC) and pancreatic neuroendocrine tumor (PNET) are yet to be investigated integrally. Therefore, in pan-cancer, particularly PC and PNET, a thorough assessment of the MTGs-OS is required.

Methods

Expression patterns, prognostic significance, mutation data, methylation rates, and pathway-regulation interactions were studied to comprehensively elucidate the involvement of MTGs-OS in pan-cancer. Next, we separated the 930 PC and 226 PNET patients into 3 clusters according to MTGs-OS expression and MTGs-OS scores. LASSO regression analysis was utilized to construct a novel prognostic model for PC. qRT-PCR(Quantitative real-time PCR) experiments were performed to verify the expression levels of model genes.

Results

The subtype associated with the poorest prognosis and lowerest MTGs-OS scores was Cluster 3, which could demonstrate the vital function of MTGs-OS for the pathophysiological processes of PC. The three clusters displayed distinct variations in the expression of conventional cancer-associated genes and the infiltration of immune cells. Similar molecular heterogeneity was observed in patients with PNET. PNET patients with S1 and S2 subtypes also showed distinct MTGs-OS scores. Given the important function of MTGs-OS in PC, a novel and robust MTGs-related prognostic signature (MTGs-RPS) was established and identified for predicting clinical outcomes for PC accurately. Patients with PC were separated into the training, internal validation, and external validation datasets at random; the expression profile of MTGs-OS was used to classify patients into high-risk (poor prognosis) or low-risk (good prognosis) categories. The variations in the tumor immune microenvironment may account for the better prognoses observed in high-risk individuals relative to low-risk ones.

Conclusions

Overall, our study for the first time identified and validated eleven MTGs-OS remarkably linked to the progression of PC and PNET, and elaborated the biological function and prognostic value of MTGs-OS. Most importantly, we established a novel protocol for the prognostic evaluation and individualized treatment for patients with PC.

Free radicals: Relationship to Human Diseases and Potential Therapeutic applications

Reactive species are highly-reactive enzymatically, or non-enzymatically produced compounds with important roles in physiological and pathophysiological cellular processes. Although reactive species represent an extensively researched topic in biomedical sciences, many aspects of their roles and functions remain unclear. This review aims to systematically summarize findings regarding the biochemical characteristics of various types of reactive species and specify the localization and mechanisms of their production in cells. In addition, we discuss the specific roles of free radicals in cellular physiology, focusing on the current lines of research that aim to identify the reactive oxygen species-initiated cascades of reactions resulting in adaptive or pathological cellular responses. Finally, we present recent findings regarding the therapeutic modulations of intracellular levels of reactive oxygen species, which may have substantial significance in developing novel agents for treating several diseases.

MS-5, a Naphthalene Derivative, Induces Apoptosis in Human Pancreatic Cancer BxPC-3 Cells by Modulating Reactive Oxygen Species

Pancreatic cancer is one of the most fatal cancers with a poor prognosis. Standard chemotherapies have proven largely ineffective because of their toxicity and the development of resistance. Therefore, there is an urgent need to develop novel therapies. In this study, we investigated the antitumor activity of MS-5, a naphthalene derivative, on BxPC-3, a human pancreatic cancer cell line. We observed that MS-5 was cytotoxic to BxPC-3 cells, as well as inhibited the growth of cells in a concentration- and time- dependent manner. Flow cytometry analysis revealed that the percentage of annexin V-positive cells increased after MS-5 treatment. We also observed cleavage of caspases and poly (ADP-ribose) polymerase, and downregulation of Bcl-xL protein. Flow cytometry analysis of intracellular levels of reactive oxygen species (ROS) and mitochondrial superoxide suggested that MS-5 induced the generation of mitochondrial superoxide while lowering the overall intracellular ROS levels. Thus, MS-5 may be potential candidate for pancreatic cancer treatment.

Senescent Human Pancreatic Stellate Cells Secrete CXCR2 Agonist CXCLs to Promote Proliferation and Migration of Human Pancreatic Cancer AsPC-1 and MIAPaCa-2 Cell Lines

Interactions between pancreatic cancer cells and pancreatic stellate cells (PSCs) play an important role in the progression of pancreatic cancer. Recent studies have shown that cellular senescence and senescence-associated secretory phenotype factors play roles in the progression of cancer. This study aimed to clarify the effects of senescence-induced PSCs on pancreatic cancer cells. Senescence was induced in primary-cultured human PSCs (hPSCs) through treatment with hydrogen peroxide or gemcitabine. Microarray and Gene Ontology analyses showed the alterations in genes and pathways related to cellular senescence and senescence-associated secretory phenotype factors, including the upregulation of C-X-C motif chemokine ligand (CXCL)-1, CXCL2, and CXCL3 through the induction of senescence in hPSCs. Conditioned media of senescent hPSCs increased the proliferation—as found in an assessment with a BrdU incorporation assay—and migration—as found in an assessment with wound-healing and two-chamber assays—of pancreatic cancer AsPC-1 and MIAPaca-2 cell lines. SB225002, a selective CXCR2 antagonist, and SCH-527123, a CXCR1/CXCR2 antagonist, attenuated the effects of conditioned media of senescent hPSCs on the proliferation and migration of pancreatic cancer cells. These results suggest a role of CXCLs as senescence-associated secretory phenotype factors in the interaction between senescent hPSCs and pancreatic cancer cells. Senescent PSCs might be novel therapeutic targets for pancreatic cancer.

Harnessing ROS-Induced Oxidative Stress for Halting Colorectal Cancer via Thiazolidinedione-Based SOD Inhibitors

Based on the "canonical" view of reactive oxygen species' (ROS) contribution to carcinogenesis, ROS induce oxidative stress and promote various tumor progression events. However, tumor cells also need to defend themselves against oxidative damage. This "heresy" was supported by several recent studies underlining the role of cellular antioxidant capacity in promoting metastasis and resistance to chemotherapy. Accordingly, harnessing the ROS-induced oxidative stress via selective suppression of the cancer antioxidant defense machinery has been launched as an innovative anticancer strategy. Within this approach, pharmacological inhibition of superoxide dismutases (SODs), the first-line defense antioxidant enzymes for cancer cells, selectively kills tumor cells and circumvents their acquired resistance. Various SOD inhibitors have been introduced, of which some were tolerated in clinical trials. However, the hit SOD inhibitors belong to diverse chemical classes and lack comprehensive structure-activity relationships (SAR). Herein, we probe the potential of newly synthesized benzylidene thiazolidinedione derivatives to inhibit SOD in colorectal cancer with special emphasis on their effects on correlated antioxidant enzymes aldehyde dehydrogenase 1 (ALDH1) and glutathione peroxidase (GPx). This may possibly bring a new dawn for utilizing thiazolidinediones (TZDs) in cancer therapy through SOD inhibition mechanisms. The preliminary 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay showed that all of the evaluated TZDs exhibited excellent safety profiles on normal human cells, recording an EC100 of up to 47.5-folds higher than that of doxorubicin. Compounds 3c, 6a, and 6e (IC50 = 4.4-4.7 μM) were superior to doxorubicin and other derivatives against Caco-2 colorectal cancer cells within their safe doses. The hit anticancer agents inhibited SOD (IC50 = 97.2-228.8 μM). Then, they were selected for further in-depth evaluation on the cellular level. The anticancer IC50 doses of 3c, 6a, and 6e diminished the antioxidant activities of SOD (by 29.7, 70.1, and 33.3%, respectively), ALDH1A (by 85.92, 95.84, and 86.48%, respectively), and GPX (by 50.17, 87.03, and 53.28%, respectively) in the treated Caco-2 cells, elevating the Caco-2 cellular content of ROS by 21.42, 7.863, and 8.986-folds, respectively. Docking simulations were conducted to display their possible binding modes and essential structural features. Also, their physicochemical parameters and pharmacokinetic profiles formulating drug-likeness were computed.

MDM2-mediated ubiquitination of LKB1 contributes to the development of diabetic cataract

Diabetic cataract (DC) is a common complication of diabetes mellitus. The epithelial-mesenchymal transition (EMT) of lens epithelial cells (LECs) is a crucial event in the development of DC. Murine double minute 2 (MDM2) is an E3 ubiquitin ligase that promotes EMT by regulating diverse targets. However, little is known about how MDM2 is involved in the pathogenesis of DC. We found the mRNA and protein levels of MDM2 were up-regulated in the lens of DC patients and rats. Thus, high glucose (HG)-induced human lens epithelial cells (HLECs) were constructed for further investigation. The results showed that the level of MDM2 was increased in HG-cultured HLECs, and the MDM2 knockdown alleviated HG-induced abnormal migration, EMT, and oxidative stress damage. Moreover, co-immunoprecipitation and ubiquitination assays demonstrated that MDM2 down-regulated LKB1 expression by ubiquitination degradation. LKB1 was found to be lower expressed in human and rat DC lenses, and HG-stimulated HLECs. Also, LKB1 overexpression mitigated HG-induced dysfunction of HLECs. Finally, our data showed that the changes related to EMT and oxidative stress induced by MDM2 knockdown were restored by down-regulation of LKB1. Together, MDM2 may involve in the pathogenesis of DC through down-regulating LKB1. MDM2 might be an effective therapeutical target of DC.

PPARγ/SOD2 Protects Against Mitochondrial ROS-Dependent Apoptosis via Inhibiting ATG4D-Mediated Mitophagy to Promote Pancreatic Cancer Proliferation

Pancreatic ductal adenocarcinoma (PDAC) is an extremely aggressive disease with poor prognosis. Our previous study found that peroxisome proliferator activated receptor gamma (PPARγ) was capable of enhancing glycolysis in PDAC cells. However, whether PPARγ could promote PDAC progression remains unclear. In our present study, PPARγ was positively associated with tumor size and poor prognosis in PDAC patients. Functional assays demonstrated that PPARγ could promote the proliferation of pancreatic cancer cells in vitro and in vivo. Additionally, flow cytometry results showed that PPARγ decreased mitochondrial reactive oxygen species (mitochondrial ROS) production, stabilized mitochondrial membrane potential (MMP) and inhibited cell apoptosis via up-regulating superoxide dismutase 2 (SOD2), followed by the inhibition of ATG4D-mediated mitophagy. Meanwhile, the activation of PPARγ might reduce pancreatic cancer cell stemness to improve PDAC chemosensitivity via down-regulating ATG4D. Thus, these results revealed that PPARγ/SOD2 might protect against mitochondrial ROS-dependent apoptosis via inhibiting ATG4D-mediated mitophagy to promote pancreatic cancer proliferation, further improving PDAC chemosensitivity.

Epithelial-mesenchymal transition and H2O2 signaling - a driver of disease progression and a vulnerability in cancers

Mutation-selective drugs constitute a great advancement in personalized anticancer treatment with increased quality of life and overall survival in cancers. However, the high adaptability and evasiveness of cancers can lead to disease progression and the development of drug resistance, which cause recurrence and metastasis. A common characteristic in advanced neoplastic cancers is the epithelial-mesenchymal transition (EMT) which is strongly interconnected with H₂O₂ signaling, increased motility and invasiveness. H₂O₂ relays its signal through the installation of oxidative posttranslational modifications on cysteines. The increased H₂O₂ levels that are associated with an EMT confer a heightened sensitivity towards the induction of ferroptosis as a recently discovered vulnerability.

Effects of Metallic and Carbon-Based Nanomaterials on Human Pancreatic Cancer Cell Lines AsPC-1 and BxPC-3

Pancreatic cancer, due to its asymptomatic development and drug-resistance, is difficult to cure. As many metallic and carbon-based nanomaterials have shown anticancer properties, we decided to investigate their potential use as anticancer agents against human pancreatic adenocarcinoma. The objective of the study was to evaluate the toxic properties of the following nanomaterials: silver (Ag), gold (Au), platinum (Pt), graphene oxide (GO), diamond (ND), and fullerenol (C₆₀(OH)₄₀) against the cell lines BxPC-3, AsPC-1, HFFF-2, and HS-5. The potential cytotoxic properties were evaluated by the assessment of the cell morphology, cell viability, and cell membrane damage. The cancer cell responses to GO and ND were analysed by determination of changes in the levels of 40 different pro-inflammatory proteins. Our studies revealed that the highest cytotoxicity was obtained after the ND treatment. Moreover, BxPC-3 cells were more sensitive to ND than AsPC-1 cells due to the ND-induced ROS production. Furthermore, in both of the cancer cell lines, ND caused an increased level of IL-8 and a decreased level of TIMP-2, whereas GO caused only decreased levels of TIMP-2 and ICAM-1 proteins. This work provides important data on the toxicity of various nanoparticles against pancreatic adenocarcinoma cell lines.

A metastasis suppressor Pt-dendrimer nanozyme for the alleviation of glioblastoma

Nanozymes are nanostructure-based materials which mimic the enzymatic characteristics of natural enzymes. Biological applications of nanozymes have been highlighted in basic research, industry, and translational medicine as a new cutting-edge tool. In this work, and for the first time, we disclose a tumor alleviation property of a nanozyme that is made up of amine-terminated sixth-generation polyamidoamine dendrimers with encapsulated tiny platinum nanoparticles. We systematically conducted the synthesis and characterization of the dendrimer-encapsulated Pt nanoparticles (denoted Pt-dendrimer) and confirmed their enzymatic function (hydrogen peroxide (H2O2) decomposition) within various cell lines (normal, cancerous), including glioblastoma (GBM) cells. By understanding the effects of the Pt-dendrimer at the gene level, especially related to cancer cell metastasis, we have thoroughly demonstrated its ability for tumor alleviation and suppressing GBM migration, invasion, and adhesion. The present findings show great promise for the application of the nanozyme for use in GBM-related basic research as well as at clinical sites.

Dual Role of Reactive Oxygen Species and their Application in Cancer Therapy

Reactive oxygen species (ROS) play a dual role in the initiation, development, suppression, and treatment of cancer. Excess ROS can induce nuclear DNA, leading to cancer initiation. Not only that, but ROS also inhibit T cells and natural killer cells and promote the recruitment and M2 polarization of macrophages; consequently, cancer cells escape immune surveillance and immune defense. Furthermore, ROS promote tumor invasion and metastasis by triggering epithelial-mesenchymal transition in tumor cells. Interestingly, massive accumulation of ROS inhibits tumor growth in two ways: (1) by blocking cancer cell proliferation by suppressing the proliferation signaling pathway, cell cycle, and the biosynthesis of nucleotides and ATP and (2) by inducing cancer cell death via activating endoplasmic reticulum stress-, mitochondrial-, and P53- apoptotic pathways and the ferroptosis pathway. Unfortunately, cancer cells can adapt to ROS via a self-adaption system. This review highlighted the bidirectional regulation of ROS in cancer. The study further discussed the application of massively accumulated ROS in cancer treatment. Of note, the dual role of ROS in cancer and the self-adaptive ability of cancer cells should be taken into consideration for cancer prevention.

Therapeutic effect of curcumin in gastrointestinal cancers: A comprehensive review

Gastrointestinal (GI) cancers with a high global prevalence are a leading cause of morbidity and mortality. Accordingly, there is a great need to develop efficient therapeutic approaches. Curcumin, a naturally occurring agent, is a promising compound with documented safety and anticancer activities. Recent studies have demonstrated the activity of curcumin in the prevention and treatment of different cancers. According to systematic studies on curcumin use in various diseases, it can be particularly effective in GI cancers because of its high bioavailability in the gastrointestinal tract. Nevertheless, the clinical applications of curcumin are largely limited because of its low solubility and low chemical stability in water. These limitations may be addressed by the use of relevant analogues or novel delivery systems. Herein, we summarize the pharmacological effects of curcumin against GI cancers. Moreover, we highlight the application of curcumin's analogues and novel delivery systems in the treatment of GI cancers.

Val16A SOD2 Polymorphism Promotes Epithelial-Mesenchymal Transition Antagonized by Muscadine Grape Skin Extract in Prostate Cancer Cells

Epithelial–mesenchymal transition (EMT), a key event in cancer metastasis, allows polarized epithelial cells to assume mesenchymal morphologies, enhancing invasiveness and migration, and can be induced by reactive oxygen species (ROS). Val16A (Ala) SOD2 polymorphism has been associated with increased prostate cancer (PCa) risk. We hypothesized that SOD2 Ala single nucleotide polymorphism (SNP) may promote EMT. We analyzed SOD2 expression and genotype in various prostate cell lines. Stable overexpression of Ala-SOD2 or Val-SOD2 allele was performed in Lymph Node Carcinoma of the Prostate (LNCaP) cells followed by analysis of intracellular ROS and EMT marker protein expression. Treatments were performed with muscadine grape skin extract (MSKE) antioxidant, with or without addition of H₂O₂ to provide further oxidative stress. Furthermore, MTS cell proliferation, cell migration, and apoptosis assays were completed. The results showed that SOD2 expression did not correlate with tumor aggressiveness nor SOD2 genotype. We demonstrated that the Ala-SOD2 allele was associated with marked induction of EMT indicated by higher Snail and vimentin, lower E-cadherin, and increased cell migration, when compared to Val-SOD2 allele or Neo control cells. Ala-SOD2 SNP cells exhibited increased levels of total ROS and superoxide and were more sensitive to co-treatment with H₂O₂ and MSKE, which led to reduced cell growth and increased apoptosis. Additionally, MSKE inhibited Ala-SOD2 SNP-mediated EMT. Our data indicates that treatment with a combination of H₂O₂-generative drugs, such as certain chemotherapeutics and antioxidants such as MSKE that targets superoxide, hold promising therapeutic potential to halt PCa progression in the future.

Traditional Chinese medicine may be further explored as candidate drugs for pancreatic cancer: A review

Pancreatic cancer is a disease with a high mortality rate. Although survival rates for different types of cancers have improved in recent years, the five-year survival rate of pancreatic cancer stands at 8%. Moreover, the current first-line therapy, gemcitabine, results in low remission rates and is associated with drug resistance problems. Alternative treatments for pancreatic cancer such as surgery, chemotherapy and radiation therapy provide marginal remission and survival rates. This calls for the search of more effective drugs or treatments. Traditional Chinese medicine contains numerous bioactive ingredients some of which show activity against pancreatic cancer. In this review, we summarize the mechanisms of five types of traditional Chinese medicine monomers. In so-doing, we provide new potential drug candidates for the treatment of pancreatic cancer.

An Integrative Omics Approach Reveals Involvement of BRCA1 in Hepatic Metastatic Progression of Colorectal Cancer

(1) Background & Aims: The roles of different cells in the tumor microenvironment (TME) are critical to the metastatic process. The phenotypic transformation of the liver cells is one of the most important stages of the hepatic metastasis progression of colorectal cancer (CRC). Our aim was to identify the major molecules (i.e., genes, miRNAs and proteins) involved in this process. (2) Methods: We isolated and performed whole-genome analysis of gene, miRNA, and protein expression in three types of liver cells (Ito cells, Kupffer cells, and liver sinusoidal endothelial cells) from the TME of a murine model of CRC liver metastasis. We selected the statistically significant differentially expressed molecules using the Student's t-test with Benjamini-Hochberg correction and performed functional statistically-significant enrichment analysis of differentially expressed molecules with hypergeometric distribution using the curated collection of molecular signatures, MSigDB. To build a gene-miRNA-protein network centered in Brca1, we developed a software package (miRDiana) that collects miRNA targets from the union of the TargetScan, MicroCosm, mirTarBase, and miRWalk databases. This was used to search for miRNAs targeting Brca1. We validated the most relevant miRNAs with real-time quantitative PCR. To investigate BRCA1 protein expression, we built tissue microarrays (TMAs) from hepatic metastases of 34 CRC patients. (3) Results: Using integrated omics analyses, we observed that the Brca1 gene is among the twenty transcripts simultaneously up-regulated in all three types of TME liver cells during metastasis. Further analysis revealed that Brca1 is the last BRCA1-associated genome surveillance complex (BASC) gene activated in the TME. We confirmed this finding in human reanalyzing transcriptomics datasets from 184 patients from non-tumor colorectal tissue, primary colorectal tumor and colorectal liver metastasis of the GEO database. We found that the most probable sequence of cell activation during metastasis is Endothelial→Ito→Kupffer. Immunohistochemical analysis of human liver metastases showed the BRCA1 protein was co-localized in Ito, Kupffer, and endothelial cells in 81.8% of early or synchronous metastases. However, in the greater part of the metachronous liver metastases, this protein was not expressed in any of these TME cells. (4) Conclusions: These results suggest a possible role of the co-expression of BRCA1 in Ito, Kupffer, and sinusoidal endothelial cells in the early occurrence of CRC liver metastases, and point to BRCA1 as a potential TME biomarker.

Lifestyle, Oxidative Stress, and Antioxidants: Back and Forth in the Pathophysiology of Chronic Diseases

Oxidative stress plays an essential role in the pathogenesis of chronic diseases such as cardiovascular diseases, diabetes, neurodegenerative diseases, and cancer. Long term exposure to increased levels of pro-oxidant factors can cause structural defects at a mitochondrial DNA level, as well as functional alteration of several enzymes and cellular structures leading to aberrations in gene expression. The modern lifestyle associated with processed food, exposure to a wide range of chemicals and lack of exercise plays an important role in oxidative stress induction. However, the use of medicinal plants with antioxidant properties has been exploited for their ability to treat or prevent several human pathologies in which oxidative stress seems to be one of the causes. In this review we discuss the diseases in which oxidative stress is one of the triggers and the plant-derived antioxidant compounds with their mechanisms of antioxidant defenses that can help in the prevention of these diseases. Finally, both the beneficial and detrimental effects of antioxidant molecules that are used to reduce oxidative stress in several human conditions are discussed.

Lifestyle, Oxidative Stress, and Antioxidants: Back and Forth in the Pathophysiology of Chronic Diseases

Oxidative stress plays an essential role in the pathogenesis of chronic diseases such as cardiovascular diseases, diabetes, neurodegenerative diseases, and cancer. Long term exposure to increased levels of pro-oxidant factors can cause structural defects at a mitochondrial DNA level, as well as functional alteration of several enzymes and cellular structures leading to aberrations in gene expression. The modern lifestyle associated with processed food, exposure to a wide range of chemicals and lack of exercise plays an important role in oxidative stress induction. However, the use of medicinal plants with antioxidant properties has been exploited for their ability to treat or prevent several human pathologies in which oxidative stress seems to be one of the causes. In this review we discuss the diseases in which oxidative stress is one of the triggers and the plant-derived antioxidant compounds with their mechanisms of antioxidant defenses that can help in the prevention of these diseases. Finally, both the beneficial and detrimental effects of antioxidant molecules that are used to reduce oxidative stress in several human conditions are discussed.

Lifestyle, Oxidative Stress, and Antioxidants: Back and Forth in the Pathophysiology of Chronic Diseases

Oxidative stress plays an essential role in the pathogenesis of chronic diseases such as cardiovascular diseases, diabetes, neurodegenerative diseases, and cancer. Long term exposure to increased levels of pro-oxidant factors can cause structural defects at a mitochondrial DNA level, as well as functional alteration of several enzymes and cellular structures leading to aberrations in gene expression. The modern lifestyle associated with processed food, exposure to a wide range of chemicals and lack of exercise plays an important role in oxidative stress induction. However, the use of medicinal plants with antioxidant properties has been exploited for their ability to treat or prevent several human pathologies in which oxidative stress seems to be one of the causes. In this review we discuss the diseases in which oxidative stress is one of the triggers and the plant-derived antioxidant compounds with their mechanisms of antioxidant defenses that can help in the prevention of these diseases. Finally, both the beneficial and detrimental effects of antioxidant molecules that are used to reduce oxidative stress in several human conditions are discussed.

FtH-Mediated ROS Dysregulation Promotes CXCL12/CXCR4 Axis Activation and EMT-Like Trans-Differentiation in Erythroleukemia K562 Cells

The cell-microenvironment communication is essential for homing of hematopoietic stem cells in stromal niches. Recent evidences support the involvement of epithelial-to-mesenchymal (EMT) process in hematopoietic stem cell homeostasis as well as in leukemia cells invasiveness and migration capability. Here, we demonstrate that the alteration of iron homeostasis and the consequent increase of redox metabolism, mediated by the stable knock down of ferritin heavy chain (FtH), enhances the expression of CXCR4 in K562 erythroleukemia cells, thus promoting CXCL12-mediated motility. Indeed, addition of the CXCR4 receptor antagonist AMD3100 reverts this effect. Upon FtH knock down K562 cells also acquire an “EMT-like” phenotype, characterized by the increase of Snail, Slug and Vimentin with the parallel loss of E-cadherin. By using fibronectin as substrate, the cell adhesion assay further shows a reduction of cell adhesion capability in FtH-silenced K562 cells. Accordingly, confocal microscopy shows that adherent K562 control cells display a variety of protrusions while FtH-silenced K562 cells remain roundish. These phenomena are largely due to the reactive oxygen species (ROS)-mediated up-regulation of HIF-1α/CXCR4 axis which, in turn, promotes the activation of NF-κB and the enhancement of EMT features. These data are confirmed by treatments with either N-acetylcysteine (NAC) or AMD3100 or NF-κB inhibitor IκB-alpha which revert the FtH-silenced K562 invasive phenotype. Overall, our findings demonstrate the existence of a direct relationship among iron metabolism, redox homeostasis and EMT in the hematological malignancies. The effects of FtH dysregulation on CXCR4/CXCL12-mediated K562 cell motility extend the meaning of iron homeostasis in the leukemia cell microenvironment.

Zwitterionic Polymer-Gated Au@TiO2 Core-Shell Nanoparticles for Imaging-Guided Combined Cancer Therapy

With advances in nanoparticle (NP) synthesis and engineering, nanoscale agents with both therapeutic and diagnostic functions have been increasingly exploited for cancer management. Herein, we synthesized a new type of zwitterionic polymer-gated Au@TiO2 core-shell nanoparticles, which showed that they could selectively target and efficiently eliminate cancer cells via photothermal therapy (PTT), photodynamic therapy (PDT), pH/NIR-induced drug release, and cationic therapy. Methods: In the present study, the multifunctional therapeutic agent [Mn@P(CitAPDMAEMA)@Au@TiO2@DOX] was prepared to treat cancer with imaging-guided combination method. Firstly, Au@TiO2 core-shell nanoparticles (NPs) were synthesized. Taking advantage of broad and strong photoabsorption and reactive oxygen species (ROS) generation, Au@TiO2 core-shell NPs facilitated the single light-induced PTT and PDT. Next, a chemotherapy drug doxorubicin (DOX) was loaded into Au@TiO2 core-shell NPs. Then, a biocompatible zwitterionic polymer P(CitAPDMAEMA) was grafted to improve the hemocompatibility of NPs and prolong the circulation time. The polymer also served as a capping or switching material for pH-triggered drug release. In addition, the cationic nature of P(CitAPDMAEMA) eased the binding to human cervical cancer (HeLa) cells and effectively inhibited their growth in acidic environments (termed cationic therapy). Moreover, with Mn2+ ions immanently chelated, Mn@P(CitAPDMAEMA)@Au@TiO2@DOX NPs were able to provide enhanced contrast under T1- or T2-weighted magnetic resonance imaging (MRI). Results: The in vitro and in vivo anticancer experiments demonstrated the tumor was effectively inhibited with minimal side effects by the multifunctional NPs. Conclusions: As far as we know, this is the first presentation of four therapeutic methods into one nanomaterial, which will open up a new dimension for the design of combined treatment.

Effects of Mangaba (Hancornia speciosa) Fruit Extract Adsorbed onto PEG Microspheres in MCF-7 Breast Cancer Cells Co-Cultured with Blood Cells

Objective: To evaluate the antitumor effects of polyethylene glycol (PEG) microspheres with adsorbed Hancornia speciosa ethanolic extract (HSEE) on blood mononuclear (MN) cells co-cultured with MCF-7 breast cancer cells. Methods: PEG microspheres were adsorbed with HSEE and examined by flow cytometry and fluorescence microscopy. MCF-7 and MN cells obtained from volunteer donors were pre-incubated alone or co-cultured (MN and MCF-7 cells) for 24 h with or without HSEE, PEG microspheres or PEG adsorbed with HSEE (PEG-HSEE). Cell viability, superoxide release and superoxide dismutase were determined. Results: Fluorescence microscopy showed that PEG microspheres were able to absorb HSEE throughout their surface. Irrespective of the treatment, the viability index of MN cells, MCF-7 and their co-culture was not affected. Superoxide release increased in co-cultured cells treated with HSEE, adsorbed or not onto PEG microspheres. In co-cultured cells, SOD levels in culture supernatant increased in the treatment with HSEE, adsorbed onto PEG microspheres or not. Conclusion: HSEE has direct effects on MN cells co-cultured with MCF-7 cells. The results suggest the benefits of Hancornia speciosa fruit consumption by women at risk of breast cancer. In addition, because PEG-HSEE maintained oxidative balance in co-cultured cells, it is a promising alternative for the treatment of tumor cells.

Use of Antimetastatic SOD3-Mimetic Albumin as a Primer in Triple Negative Breast Cancer

Of the deaths attributed to cancer, 90% are due to metastasis. Treatments that prevent or cure metastasis remain elusive. Low expression of extracellular superoxide dismutase (EcSOD or SOD3) has been associated with poor outcomes and increased metastatic potential in multiple types of cancer. Here, we characterize the antimetastatic therapeutic mechanisms of a macromolecular extracellular SOD3-mimetic polynitroxyl albumin (PNA, also known as VACNO). PNA is macromolecular human serum albumin conjugated with multiple nitroxide groups and acts as an SOD-mimetic. Here we show that PNA works as a SOD3-mimetic in a highly metastatic 4T1 mouse model of triple negative breast cancer (TNBC). In vitro, PNA dose dependently inhibited 4T1 proliferation, colony formation, and reactive oxygen species (ROS) formation. In vivo, PNA enhanced reperfusion time in the hypoxic cores of 4T1 tumors as measured by ultrasound imaging. Furthermore, PNA enhanced ultrasound signal intensity within the cores of the 4T1 tumors, indicating PNA can increase blood flow and blood volume within the hypoxic cores of tumors. Lung metastasis from 4T1 flank tumor was inhibited by PNA in the presence or absence of doxorubicin, a chemotherapy agent that produces superoxide and promotes metastasis. In a separate study, PNA increased the survival of mice with 4T1 flank tumors when used in conjunction with three standard chemotherapy drugs (paclitaxel, doxorubicin, and cyclophosphamide), as compared to treatment with chemotherapy alone. In this study, PNA-increased survival was also correlated with reduction of lung metastasis. These results support the hypothesis that PNA works through the inhibition of extracellular superoxide/ROS production leading to the conversion of 4T1 cells from a metastatic tumorigenic state to a cytostatic state. These findings support future clinical trials of PNA as an antimetastatic SOD3-mimetic drug to increase overall survival in TNBC patients.

Modulation of Antioxidant Potential with Coenzyme Q10 Suppressed Invasion of Temozolomide-Resistant Rat Glioma In Vitro and In Vivo

The main reasons for the inefficiency of standard glioblastoma (GBM) therapy are the occurrence of chemoresistance and the invasion of GBM cells into surrounding brain tissues. New therapeutic approaches obstructing these processes may provide substantial survival improvements. The purpose of this study was to assess the potential of lipophilic antioxidant coenzyme Q10 (CoQ10) as a scavenger of reactive oxygen species (ROS) to increase sensitivity to temozolomide (TMZ) and suppress glioma cell invasion. To that end, we used a previously established TMZ-resistant RC6 rat glioma cell line, characterized by increased production of ROS, altered antioxidative capacity, and high invasion potential. CoQ10 in combination with TMZ exerted a synergistic antiproliferative effect. These results were confirmed in a 3D model of microfluidic devices showing that the CoQ10 and TMZ combination is more cytotoxic to RC6 cells than TMZ monotherapy. In addition, cotreatment with TMZ increased expression of mitochondrial antioxidant enzymes in RC6 cells. The anti-invasive potential of the combined treatment was shown by gelatin degradation, Matrigel invasion, and 3D spheroid invasion assays as well as in animal models. Inhibition of MMP9 gene expression as well as decreased N-cadherin and vimentin protein expression implied that CoQ10 can suppress invasiveness and the epithelial to mesenchymal transition in RC6 cells. Therefore, our data provide evidences in favor of CoQ10 supplementation to standard GBM treatment due to its potential to inhibit GBM invasion through modulation of the antioxidant capacity.

Cancer cells change their glucose metabolism to overcome increased ROS: One step from cancer cell to cancer stem cell?

Cancer cells can adapt to low energy sources in the face of ATP depletion as well as to their high levels of ROS by altering their metabolism and energy production networks which might also have a role in determining cell fate and developing drug resistance. Cancer cells are generally characterized by increased glycolysis. This is while; cancer stem cells (CSCs) exhibit an enhanced pentose phosphate pathway (PPP) metabolism. Based on the current literature, we suggest that cancer cells when encountering ROS, first increase the glycolysis rate and then following the continuation of oxidative stress, the metabolic balance is skewed from glycolysis to PPP. Therefore, we hypothesize in this review that in cancer cells this metabolic deviation during persistent oxidative stress might be a sign of cancer cells' shift towards CSCs, an issue that might be pivotal in more effective targeting of cancer cells and CSCs.

The role of DNA methylation in human trophoblast differentiation

The placenta is a vital fetal exchange organ connecting mother and baby. Specialised placental epithelial cells, called trophoblasts, are essential for adequate placental function. Trophoblasts transform the maternal vasculature to allow efficient blood flow to the placenta and facilitate adequate nutrient uptake. Placental development is in part regulated by epigenetic mechanisms. However, our understanding of how DNA methylation contributes to human trophoblast differentiation is limited. To better understand how genome-wide methylation differences affect trophoblast differentiation, reduced representation bisulfite sequencing (RRBS) was conducted on four matched sets of trophoblasts; side-population trophoblasts (a candidate human trophoblast stem cell population), cytotrophoblasts (an intermediate progenitor population), and extravillous trophoblasts (EVT, a terminally differentiated population) each isolated from the same first trimester placenta. Each trophoblast population had a distinct methylome. In line with their close differentiation relationship, the methylation profile of side-population trophoblasts was most similar to cytotrophoblasts, whilst EVT had the most distinct methylome. In comparison to mature trophoblast populations, side-population trophoblasts exhibited differential methylation of genes and miRNAs involved in cell cycle regulation, differentiation, and regulation of pluripotency. A combined methylomic and transcriptomic approach was taken to better understand cytotrophoblast differentiation to EVT. This revealed methylation of 41 genes involved in epithelial to mesenchymal transition and metastatic cancer pathways, which likely contributes to the acquisition of an invasive EVT phenotype. However, the methylation status of a gene did not always predict gene expression. Therefore, while CpG methylation plays a role in trophoblast differentiation, it is likely not the only regulatory mechanism involved in this process.

Targeting Cancer with Phytochemicals via Their Fine Tuning of the Cell Survival Signaling Pathways

The role of phytochemicals as potential prodrugs or therapeutic substances against tumors has come in the spotlight in the very recent years, thanks to the huge mass of encouraging and promising results of the in vitro activity of many phenolic compounds from plant raw extracts against many cancer cell lines. Little but important evidence can be retrieved from the clinical and nutritional scientific literature, where flavonoids are investigated as major pro-apoptotic and anti-metastatic compounds. However, the actual role of these compounds in cancer is still far to be fully elucidated. Many of these phytochemicals act in a pleiotropic and poorly specific manner, but, more importantly, they are able to tune the reactive oxygen species (ROS) signaling to activate a survival or a pro-autophagic and pro-apoptosis mechanism, depending on the oxidative stress-responsive endowment of the targeted cell. This review will try to focus on this issue.

Inhibitory Effect of Anoectochilus formosanus Extract on Hyperglycemia-Related PD-L1 Expression and Cancer Proliferation

Traditional herb medicine, golden thread (Anoectochilus formosanus Hayata) has been used to treat various diseases. Hyperglycemia induces generation of reactive oxygen species (ROS) and enhancement of oxidative stress which are risk factors for cancer progression and metastasis. In this study, we evaluated hypoglycemic effect of A. formosanus extracts (AFEs) in an inducible hyperglycemia animal model and its capacity of free-radical scavenging to establish hyperglycemia-related carcinogenesis. AFE reduced blood glucose in hyperglycemic mice while there was no change in control group. The incremental area under blood glucose response curve was decreased significantly in hyperglycemic mice treated with AFE in a dose-dependent manner. AFE and metformin at the same administrated dose of 50 mg/kg showed similar effect on intraperitoneal glucose tolerance test in hyperglycemic mice. Free-radical scavenger capacity of AFE was concentration dependent and 200 μg/ml of AFE was able to reduce more than 41% of the free radical. Treatment of cancer cells with AFE inhibited constitutive PD-L1 expression and its protein accumulation. It also induced expression of pro-apoptotic genes but inhibited proliferative and metastatic genes. In addition, it induced anti-proliferation in cancer cells. The results suggested that AFE not only reduced blood glucose concentration as metformin but also showed its potential use in cancer immune chemoprevention/therapy via hypoglycemic effect, ROS scavenging and PD-L1 suppression.

Elevated G6PD expression contributes to migration and invasion of hepatocellular carcinoma cells by inducing epithelial-mesenchymal transition

Altered metabolism is one of the hallmarks of cancer cells. Pentose phosphate pathway (PPP) is a fundamental component of cellular metabolism. Glucose-6-phosphate dehydrogenase (G6PD), the rate-limiting enzyme of the PPP, is elevated in many cancers and contributes to tumor growth by producing ribose-5-phosphate and NADPH through PPP. However, the role of G6PD in hepatocellular carcinoma (HCC) metastasis and the clinical significance of G6PD in HCC progression and prognosis have not been well determined. In this study, by investigating tissue samples from HCC patients and HCC cell lines, we found that elevated G6PD expression is significantly associated with HCC metastasis and poor prognosis of HCCs, and that knockdown of G6PD inhibits in vitro proliferation, migration and invasion of HCC cell lines. Further studies reveal that G6PD contributes to HCC migration and invasion of hepatocellular carcinoma cells by inducing epithelial-mesenchymal transition through activation of signal transducer and activator of transcription 3 (STAT3) pathway. Our findings suggest that targeting G6PD could open up possibilities for metastasis intervention and improve the patients' outcomes for HCC.

Curcumin inhibits superoxide dismutase-induced epithelial-to-mesenchymal transition via the PI3K/Akt/NF-κB pathway in pancreatic cancer cells

Curcumin is a natural polyphenol compound derived from turmeric. It possesses multiple pharmacological properties, including antioxidant, anti-inflammatory and anti-tumor progression properties. Our recent study demonstrated that superoxide dismutase (SOD)-dependent production of hydrogen peroxide (H2O2) promoted the invasive and migratory activity of pancreatic cancer cells. However, whether curcumin suppresses SOD-induced cancer progression and the related mechanisms remains unclear. Since epithelial‑to-mesenchymal transition (EMT) plays a key role in tumor metastasis, the aim of the present study was to examine whether curcumin intervenes with SOD-induced EMT in pancreatic cancer and the underlying mechanism. The human pancreatic cancer cells BxPC-3 and Panc-1 were exposed to SOD in the presence or absence of curcumin, catalase (CAT, a scavenger of H2O2), or LY 294002 [a phosphoinositide-3 kinase (PI3K) inhibitor]. Intracellular reactive oxygen species (ROS) and H2O2 were evaluated by 2,7-dichlorodihydrofluorecein diacetate and H2O2 assay, respectively. The activation of p-Akt and p-nuclear factor (NF)-κB were examined by western blotting. The migratory and invasive abilities of pancreatic cancer cells were tested by the wound healing and Transwell invasion assays. The expression of E-cadherin, N-cadherin and vimentin (EMT-related genes) were measured by reverse transcription-quantitative polymerase chain reaction and western blotting at the mRNA and protein levels, respectively. The findings of the present study demonstrated that curcumin decreased SOD-induced production of ROS and H2O2 in BxPC-3 and Panc-1 cells. Curcumin was able to suppress SOD-induced invasion and migration, and it also regulated the expression of the above‑mentioned EMT-related genes and cell morphology. SOD-induced cell invasion was also inhibited by catalase and LY 294002. Furthermore, the levels of p-Akt and p-NF-κB caused by SOD could be offset by treatment with curcumin and LY 294002. To summarize, these results demonstrated that curcumin was able to prevent SOD-driven H2O2-induced pancreatic cancer metastasis by blocking the PI3K/Akt/NF-κB signaling pathway. The use of curcumin to inhibit the H2O2/Akt/NF-κB axis may be a promising therapeutic approach to the treatment of patients with pancreatic cancer.

Redox regulation in tumor cell epithelial-mesenchymal transition: molecular basis and therapeutic strategy

Epithelial–mesenchymal transition (EMT) is recognized as a driving force of cancer cell metastasis and drug resistance, two leading causes of cancer recurrence and cancer-related death. It is, therefore, logical in cancer therapy to target the EMT switch to prevent such cancer metastasis and recurrence. Previous reports have indicated that growth factors (such as epidermal growth factor and fibroblast growth factor) and cytokines (such as the transforming growth factor beta (TGF-β) family) are major stimulators of EMT. However, the mechanisms underlying EMT initiation and progression remain unclear. Recently, emerging evidence has suggested that reactive oxygen species (ROS), important cellular secondary messengers involved in diverse biological events in cancer cells, play essential roles in the EMT process in cancer cells by regulating extracellular matrix (ECM) remodeling, cytoskeleton remodeling, cell–cell junctions, and cell mobility. Thus, targeting EMT by manipulating the intracellular redox status may hold promise for cancer therapy. Herein, we will address recent advances in redox biology involved in the EMT process in cancer cells, which will contribute to the development of novel therapeutic strategies by targeting redox-regulated EMT for cancer treatment.

Hyperglycemia Promotes the Epithelial-Mesenchymal Transition of Pancreatic Cancer via Hydrogen Peroxide

Diabetes mellitus (DM) and pancreatic cancer are intimately related, as approximately 85% of patients diagnosed with pancreatic cancer have impaired glucose tolerance or even DM. Our previous studies have indicated that high glucose could promote the invasive and migratory abilities of pancreatic cancer cells. We therefore explored the underlying mechanism that hyperglycemia modulates the metastatic potential of pancreatic cancer. Our data showed that streptozotocin- (STZ-) treated diabetic nude mice exhibit larger tumor size than that of the euglycemic mice. The number of nude mice that develop liver metastasis or ascites is much more in the STZ-treated group than that in the euglycemic group. Hyperglycemic mice contain a higher plasma H₂O₂-level than that from euglycemic mice. The injection of polyethylene glycol-conjugated catalase (PEG-CAT), an H₂O₂ scavenger, may reverse hyperglycemia-induced tumor metastasis. In addition, hyperglycemia could also modulate the expression of epithelial-mesenchymal transition- (EMT-) related factors in pancreatic tumor tissues, as the E-cadherin level is decreased and the expression of mesenchymal markers N-cadherin and vimentin as well as transcription factor snail is strongly increased. The injection of PEG-CAT could also reverse hyperglycemia-induced EMT. These results suggest that the association between hyperglycemia and poor prognosis of pancreatic cancer can be attributed to the alterations of EMT through the production of hydrogen peroxide.

Resveratrol inhibits hyperglycemia-driven ROS-induced invasion and migration of pancreatic cancer cells via suppression of the ERK and p38 MAPK signaling pathways

Increasing evidence suggests that there is a strong relationship between diabetes mellitus (DM) and pancreatic cancer. Our previous study revealed that hyperglycemia could enhance the invasive and migratory activities of pancreatic cancer cells. Resveratrol, a natural polyphenolic phytoalexin, has many biological and pharmaceutical properties, including antioxidant and anti-tumorigenic capabilities. The aim of the present study was to evaluate whether resveratrol affects hyperglycemia-induced reactive oxygen species (ROS) production as well as the invasion and migration of pancreatic cancer and its underlying mechanisms. Human pancreatic cancer Panc-1 cells were exposed to high glucose condition with or without resveratrol, N-acetylcysteine (NAC, a scavenger of free radicals), PD 98059 (an ERK inhibitor) or SB 203580 (a p38 MAPK inhibitor). The intracellular ROS and hydrogen peroxide (H2O2) were determined using 2,7-dichlorodihydrofluorecein diacetate and H2O2 assay. MTT, wound healing assay and transwell matrigel invasion assay were used to detect the proliferation, migration and invasion potential of cancer cells. The expressions of uPA, E-cadherin and Glut-1 were examined using QT-PCR and western blot analysis at mRNA and protein levels. The activation of p-ERK, p-p38 and p-NF-κB were measured by western blot analysis. The results of the present study showed that resveratrol could significantly decrease high glucose-induced production of ROS and H2O2 in Panc-1 cells. Resveratrol was also able to inhibit high glucose-induced proliferation, migration and invasion of pancreatic cancer cells. High glucose-modulated expression of uPA, E-cadherin and Glut-1 were inhibited by resveratrol. In addition, high glucose-induced activation of ERK and p38 MAPK signaling pathways as well as the transcription factor NF-κB could also be suppressed by resveratrol. Furthermore, resveratrol was able to suppress H2O2-induced migration and invasion abilities of pancreatic cancer cells. Taken together, these data indicate that resveratrol plays an important role in suppressing hyperglycemia-driven ROS-induced pancreatic cancer progression by inhibiting the ERK and p38 MAPK signaling pathways, providing evidence that resveratrol might be a potential candidate for chemoprevention of pancreatic cancer.

Curcumin inhibits hypoxia-induced epithelial‑mesenchymal transition in pancreatic cancer cells via suppression of the hedgehog signaling pathway

Hypoxic microenvironment, a common feature of pancreatic cancer, is associated with tumor proliferation, metastasis and epithelial-mesenchymal transition (EMT) changes. In recent years, many natural agents, including curcumin, have been proven to possess the ability to inhibit the progression of pancreatic cancer. However, whether curcumin is able to suppress hypoxia-induced pancreatic cancer progression and the underlying mechanisms are still not fully elucidated. The aim of the present study was to evaluate whether curcumin affects hypoxia-induced EMT and the activation of Hh signaling pathway in pancreatic cancer. The human pancreatic cancer cell line Panc-1, was treated with hypoxic condition and curcumin. Cell proliferation was assessed by the MTT assay. Wound healing assay and transwell invasion assay were used to detect the migratory and invasive activity of cancer cells. The EMT-related factors, E-cadherin, N-cadherin, vimentin were detected by QT-PCR, western blot analysis and immunofluorescence staining. The Hh signaling-related factors, SHH, SMO and GLI1 were detected by western blot analysis. The results of present study showed that curcumin could not only inhibit the hypoxia-induced cell proliferation, migration and invasion in pancreatic cancer, but also mediate the expression of EMT-related factors. In addition, curcumin remarkably inhibited hypoxia-mediated activation of Hh signaling pathway. Taken together, these data indicate that curcumin plays an important role in suppressing hypoxia-induced pancreatic cancer metastasis by inhibiting the Hh signaling pathway. Curcumin might be a potential candidate for chemoprevention of this severe disease.

Decreased expression of E-cadherin by Porphyromonas gingivalis-lipopolysaccharide attenuates epithelial barrier function

BACKGROUND AND OBJECTIVE

The gingival epithelium is a first line of defense against bacterial challenge. E-cadherin (E-cad) plays an important role in cell-cell adhesion as a barrier in the epithelium. Recently, a decrease in the expression of E-cad has been observed in inflamed gingival tissue. The aims of this study were to clarify the changes in E-cad expression and barrier function in human gingival epithelial cells stimulated with Porphyromonas gingivalis-lipopolysaccharide (P. gingivalis-LPS) and to evaluate the influence of these changes on the inflammatory reaction. Furthermore, to clarify the mechanism of the E-cad changes induced by P. gingivalis-LPS, we focused on reactive oxygen species (ROS) that are reported to induce a decrease in E-cad expression.

MATERIAL AND METHODS

Human gingival epithelial cells were incubated in Humedia-KG2 in the presence or absence of P. gingivalis-LPS and antioxidants to analyze ROS involvement in P. gingivalis-LPS-induced E-cad changes. E-cad protein expression was analyzed by immunofluorescence staining. To investigate barrier function and inflammatory changes, we performed transport and cytokine assays using gingival epithelial cells and macrophages co-culture model in transwell plates. Medium containing 10 μg/mL P. gingivalis-LPS (transport substance) was added to the upper compartment, which harvested gingival epithelial cells, and medium without P. gingivalis-LPS was added to the lower compartment, which harvested macrophages. In the transport assay, P. gingivalis-LPS penetration was analyzed using the Limulus amebocyte lysate test. In the cytokine assay, we examined the change in tumor necrosis factor-α (TNF-α) production from the macrophages in the lower compartment using enzyme-linked immunosorbent assay.

RESULTS

Expression of E-cad in human gingival epithelial cells was decreased by P. gingivalis-LPS, and the decrease in E-cad accelerated the penetration of P. gingivalis-LPS through the monolayer. In addition, the concentration of TNF-α was higher under the E-cad reduced monolayer. Antioxidants, particularly vitamin E and l-ascorbic acid 2-phosphate magnesium salt, inhibited the decrease in E-cad expression, penetration of P. gingivalis-LPS and increase in TNF-α.

CONCLUSION

These results suggest that the decrease in E-cad caused by P. gingivalis-LPS leads to destruction of the epithelial barrier function in human gingival epithelial cells, and finally accelerates the inflammatory reaction under the barrier. Antioxidants, particularly vitamin E and l-ascorbic acid 2-phosphate magnesium salt, may restore the impaired function by scavenging ROS, which are related to the decrease in E-cad expression by P. gingivalis-LPS.

Reactive Oxygen Species and Targeted Therapy for Pancreatic Cancer

Pancreatic cancer is the fourth leading cause of cancer-related death in the United States. Reactive oxygen species (ROS) are generally increased in pancreatic cancer cells compared with normal cells. ROS plays a vital role in various cellular biological activities including proliferation, growth, apoptosis, and invasion. Besides, ROS participates in tumor microenvironment orchestration. The role of ROS is a doubled-edged sword in pancreatic cancer. The dual roles of ROS depend on the concentration. ROS facilitates carcinogenesis and cancer progression with mild-to-moderate elevated levels, while excessive ROS damages cancer cells dramatically and leads to cell death. Based on the recent knowledge, either promoting ROS generation to increase the concentration of ROS with extremely high levels or enhancing ROS scavenging ability to decrease ROS levels may benefit the treatment of pancreatic cancer. However, when faced with oxidative stress, the antioxidant programs of cancer cells have been activated to help cancer cells to survive in the adverse condition. Furthermore, ROS signaling and antioxidant programs play the vital roles in the progression of pancreatic cancer and in the response to cancer treatment. Eventually, it may be the novel target for various strategies and drugs to modulate ROS levels in pancreatic cancer therapy.

Lipoxin A4 Attenuates Cell Invasion by Inhibiting ROS/ERK/MMP Pathway in Pancreatic Cancer

Lipoxin A₄ (LXA₄), an endogenous arachidonic acid metabolite, was previously considered an anti-inflammatory lipid mediator. But it also has the potential to inhibit cancer progression. To explore the therapeutic effect of LXA₄ in pancreatic cancer, we used Panc-1 cells to investigate the mechanism by which LXA₄ can attenuate pancreatic cancer cell invasion. Our data showed that LXA₄ significantly inhibited both cell invasion and the expression of matrix metalloproteinase- (MMP-) 9 and MMP-2. Further experiments implied that LXA₄ decreased the levels of intracellular reactive oxygen species (ROS) and the activity of the extracellular signal regulated kinases (ERK) pathway to achieve similar outcome to ROS scavenger N-acetyl-l-cysteine (NAC). However, a decreased level of intracellular ROS was not observed in cells treated with the specific ERK pathway inhibitor FR180204. The blocking of either intracellular ROS or ERK pathway caused the downregulation of MMP-9 and MMP-2 expression. Furthermore, tests revealed that LXA₄ inhibited MMP-9 and MMP-2 at the mRNA, protein, and functional levels. Finally, LXA₄ dramatically limited the invasion of CoCl₂-mimic hypoxic cells and abrogated intracellular ROS levels, ERK activity, and MMPs expression. These results suggest that LXA₄ attenuates cell invasion in pancreatic cancer by suppressing the ROS/ERK/MMPs pathway, which may be beneficial for preventing the invasion of pancreatic cancer.