The Double-Edged Sword Profile of Redox Signaling: Oxidative Events As Molecular Switches in the Balance between Cell Physiology and Cancer

Pelargonidin inhibits cell growth and promotes oxidative stress-mediated apoptosis in lung cancer A549 cells

Lung cancer has the worst prognosis with an average 5-year survival rate of only 10%-20%. Lung cancer has the highest prevalence rate and a second most common cause of cancer-associated mortalities worldwide. The present study was planned to explore the anticancer effects of pelargonidin against the lung cancer A549 cells via analyzing oxidative stress-mediated apoptosis. The viability of both control and pelargonidin-treated A549 cells was analyzed using the MTT cytotoxicity assay at different time periods. The levels of endogenous ROS generation, mitochondrial membrane potential (Δψm), and apoptosis were assessed using corresponding fluorescent staining assays. The levels of oxidative stress biomarkers, including TBARS, SOD, CAT, and GSH, in the cell lysates of control and pelargonidin-treated A549 cells were examined using the assay kits. The pelargonidin treatment substantially suppressed the A549 cell growth. Further, pelargonidin promoted the ROS production and depleted the Δψm levels in the A549 cells. The fluorescent staining assays witnessed the occurrence of increased apoptosis in the pelargonidin-treated A549 cells. The pelargonidin also boosted the TBARS and reduced the antioxidant levels thereby promoted the oxidative stress-regulated apoptosis in the A549 cells. In summary, the findings' results of the current study demonstrated an anticancer activity of pelargonidin on A549 cells. The pelargonidin treatment substantially decreased the growth and encouraged the oxidative stress-regulated apoptosis in A549 cells. Therefore, it was evident that the pelargonidin could be employed as an effective anticancer candidate to treat the lung cancer.

A pilot study of mitochondrial response to an in vivo prosthetic joint Staphylococcus aureus infection model

Prosthetic joint infections (PJI) are associated with orthopaedic morbidity and mortality. Mitochondria, the "cell's powerhouses," are thought to play crucial roles in infection response and in increased risk of sepsis mortality. No current research discusses PJI's effect on mitochondrial function and a lack of understanding of immune-infection interactions potentially hinders patient care. The purpose of this pilot study was to evaluate the impact of simulated PJI on local tissue mitochondrial function. Using an established prosthetic implant-associated in vivo model, tissues were harvested from the surgical limb of a methicillin-sensitive Staphylococcus aureus implant-associated infection group (n = 6) and compared to a noninfected group (n = 6) at postoperative day (POD) 21. Using mitochondrial coupling assays, oxygen consumption rate and extracellular acidification rate were assessed in each group. Electron flow through mitochondrial complexes reflected group activity. Electron Paramagnetic Resonance (EPR) spectrometry measured the oxidizing potential of serum samples from infected versus noninfected groups. On POD21, colony-forming units per gram of tissue showed 5 × 109 in the infected group and 101 in the noninfected group (p < 0.0001). Maximal respiration and oxygen consumption due to adenosine triphosphate synthesis were significantly lower in isolated mitochondria from infected limbs (p = 0.04). Both groups had similar complex I, III, IV, and V activity (p > 0.1). Infected group EPR signal intensity reflecting reactive oxygen species levels was 1.31 ± 0.30 compared to 1.16 ± 0.28 (p = 0.73) in the noninfected group. This study highlights PJI's role in mammalian cell mitochondrial dysfunction and oxidative tissue damage, which can help develop interventions to combat PJI.

Biomarkers in Laryngeal Squamous Cell Carcinoma: The Literature Review

Laryngeal squamous cell carcinoma (LSCC) is the second most common cancer among head and neck cancers. Despite a lower incidence of laryngeal carcinoma, new diagnostic techniques, and more targeted therapies, the overall survival has not changed significantly in the last decades, leading to a negative prognosis in advanced stages. Recently, several studies have focused on the identification of biomarkers that may play a critical role in the pathogenesis of LSCC. Reviewing the literature on the main databases, this study aims to investigate the role of some biomarkers in LSCC that are correlated with oxidative stress and inflammation: heat shock proteins; metallothioneins; nuclear factor erythroid 2-related factor 2; heme oxygenase; cyclooxygenase-2; and micro ribonucleic acids. This review shows that biomarker expression depends on the type, grade of differentiation, stage, and site of carcinoma. In addition, the role of these biomarkers in LSCC is still little-known and little-studied. However, the study of biomarker expression and the detection of a possible correlation with patients' epidemiological, clinicopathological, and therapeutics data may lead to better awareness and knowledge of the tumor, to the identification of the best therapeutic strategy, and the most proper follow-up protocol tailored for each patient. In conclusion, the achievement of these goals may improve the prognosis of LSCC patients.

Foodomics-Based Approaches Shed Light on the Potential Protective Effects of Polyphenols in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a chronic and progressive inflammatory disorder affecting the gastrointestinal tract (GT) caused by a wide range of genetic, microbial, and environmental factors. IBD is characterized by chronic inflammation and decreased gut microbial diversity, dysbiosis, with a lower number of beneficial bacteria and a concomitant increase in pathogenic species. It is well known that dysbiosis is closely related to the induction of inflammation and oxidative stress, the latter caused by an imbalance between reactive oxygen species (ROS) production and cellular antioxidant capacity, leading to cellular ROS accumulation. ROS are responsible for intestinal epithelium oxidative damage and the increased intestinal permeability found in IBD patients, and their reduction could represent a potential therapeutic strategy to limit IBD progression and alleviate its symptoms. Recent evidence has highlighted that dietary polyphenols, the natural antioxidants, can maintain redox equilibrium in the GT, preventing gut dysbiosis, intestinal epithelium damage, and radical inflammatory responses. Here, we suggest that the relatively new foodomics approaches, together with new technologies for promoting the antioxidative properties of dietary polyphenols, including novel delivery systems, chemical modifications, and combination strategies, may provide critical insights to determine the clinical value of polyphenols for IBD therapy and a comprehensive perspective for implementing natural antioxidants as potential IBD candidate treatment.

Endogenous and Exogenous Antioxidants as Agents Preventing the Negative Effects of Contrast Media (Contrast-Induced Nephropathy)

The use of conventional contrast media for diagnostic purposes (in particular, Gd-containing and iodinated agents) causes a large number of complications, the most common of which is contrast-induced nephropathy. It has been shown that after exposure to contrast agents, oxidative stress often occurs in patients, especially in people suffering from various diseases. Antioxidants in the human body can diminish the pathological consequences of the use of contrast media by suppressing oxidative stress. This review considers the research studies on the role of antioxidants in preventing the negative consequences of the use of contrast agents in diagnostics (mainly contrast-induced nephropathy) and the clinical trials of different antioxidant drugs against contrast-induced nephropathy. Composite antioxidant/contrast systems as theranostic agents are also considered.

Endogenous and Exogenous Regulation of Redox Homeostasis in Retinal Pigment Epithelium Cells: An Updated Antioxidant Perspective

The retinal pigment epithelium (RPE) performs a range of necessary functions within the neural layers of the retina and helps ensure vision. The regulation of pro-oxidative and antioxidant processes is the basis for maintaining RPE homeostasis and preventing retinal degenerative processes. Long-term stable changes in the redox balance under the influence of endogenous or exogenous factors can lead to oxidative stress (OS) and the development of a number of retinal pathologies associated with RPE dysfunction, and can eventually lead to vision loss. Reparative autophagy, ubiquitin-proteasome utilization, the repair of damaged proteins, and the maintenance of their conformational structure are important interrelated mechanisms of the endogenous defense system that protects against oxidative damage. Antioxidant protection of RPE cells is realized as a result of the activity of specific transcription factors, a large group of enzymes, chaperone proteins, etc., which form many signaling pathways in the RPE and the retina. Here, we discuss the role of the key components of the antioxidant defense system (ADS) in the cellular response of the RPE against OS. Understanding the role and interactions of OS mediators and the components of the ADS contributes to the formation of ideas about the subtle mechanisms in the regulation of RPE cellular functions and prospects for experimental approaches to restore RPE functions.

Ethanolic extract of Ocimum sanctum leaf modulates oxidative stress, cell cycle and apoptosis in head and neck cancer cell lines

Ocimum sanctum Linn. is a medicinal herb that has cytotoxic effects by inducing oxidative stress in some carcinomas. This study aimed to examine the impact of O. sanctum leaf extract on oxidative stress, cell cycle progression, and apoptosis in cell lines of head and neck squamous cell carcinoma (HNSCC). Isogenic primary (HN18/HN30) and metastatic (HN17/HN31) HNSCC cell lines were used. Preparation of the ethanolic extract of O. sanctum leaf (EEOS) was carried out. HNSCC cell lines were exposed to varying concentrations (0.1-0.8 mg/ml) of EEOS for a duration of 72 h, and the MTT assay was utilized to determine the cytotoxic doses. To assess the impact of EEOS on HNSCC cells, the levels of reactive oxygen species (ROS) and malondialdehyde were measured using a fluorometric method. Flow cytometry was utilized to evaluate effects of EEOS on the cell cycle, DNA damage, and apoptosis in HNSCC cells. Caspase-3 and -9 levels in the EEOS-treated HNSCC cells were measured by ELISA. The chemical components in EEOS were detected using high-performance liquid chromatography-electrospray ionization-time of flight-mass spectrometry. EEOS exhibited cytotoxicity against the HN18, HN17, HN30 and HN31 cells at minimum concentrations of 0.1, 0.3, 0.2 and 0.2 mg/ml, respectively. Treatment with EEOS resulted in a significant increase in ROS levels in HN18 and HN17 cells. Additionally, EEOS significantly induced the levels of malondialdehyde in HN18 and HN31 cells. Moreover, EEOS arrested the cell cycle in HN30 and HN31 cells, and significantly induced DNA damage and apoptosis in the HN18, HN30, and HN31 cells. EEOS selectively increased caspase-9 in the HN18 cells. However, caspase-3 was activated without apoptosis in the EEOS-treated HN17 cells. The constituents of EEOS were identified as rosmarinic acid, caffeic acid, and apigenin. In conclusion, EEOS exhibits various prooxidative and apoptotic effects between HNSCC cells.

Single-Cell Kinetic Modeling of β-Lapachone Metabolism in Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC) cells are highly heterogeneous in their metabolism and typically experience elevated reactive oxygen species (ROS) levels such as superoxide and hydrogen peroxide (H2O2) in the tumor microenvironment. Tumor cells survive under these chronic oxidative conditions by upregulating antioxidant systems. To investigate the heterogeneity of cellular responses to chemotherapeutic H2O2 generation in tumor and healthy tissue, we leveraged single-cell RNA-sequencing (scRNA-seq) data to perform redox systems-level simulations of quinone-cycling β-lapachone treatment as a source of NQO1-dependent rapid superoxide and hydrogen peroxide (H2O2) production. Transcriptomic data from 10 HNSCC patient tumors was used to populate over 4000 single-cell antioxidant enzymatic network models of drug metabolism. The simulations reflected significant systems-level differences between the redox states of healthy and cancer cells, demonstrating in some patient samples a targetable cancer cell population or in others statistically indistinguishable effects between non-malignant and malignant cells. Subsequent multivariate analyses between healthy and malignant cellular models pointed to distinct contributors of redox responses between these phenotypes. This model framework provides a mechanistic basis for explaining mixed outcomes of NAD(P)H:quinone oxidoreductase 1 (NQO1)-bioactivatable therapeutics despite the tumor specificity of these drugs as defined by NQO1/catalase expression and highlights the role of alternate antioxidant components in dictating drug-induced oxidative stress.

Synthesis, conformation and cytotoxic activity of short hybrid peptides containing conformationally constrained 1-(aminomethyl)cyclohexanecarboxylic acid and gabapentin

The present work describes the synthesis,conformation and cytotoxic activities of short β/γ hybrid peptides, Boc-β^2,2-Ac₆c-Gpn-NHMe, BG1; Boc-(β^2,2-Ac₆c-Gpn)₂-OMe, BG2; Boc-(β^2,2-Ac₆c-Gpn)₃-OMe, BG3; H-β^2,2-Ac₆c-Gpn-NHMe, BG4; H-(β^2,2-Ac₆c-Gpn)₂-OMe, BG5; H-(β^2,2-Ac₆c-Gpn)₃-OMe, BG6, Boc-β^2,2-Ac₆c-Gpn-OMe, BG7 and H-β^2,2-Ac₆c-Gpn-OMe, BG8. Mixed C₆/C₇ conformations were observed for β/γ hybrid peptides. Further, BG1-BG8 were screened against MCF-7 (Breast cancer), A549 (Lung Cancer), PC-3 (Prostate cancer), HCT-116 (Colon cancer), and MDA-MB-231 (Breast cancer) cell lines. Among all, BG6 exhibited potent cytotoxicity against all cancer cell lines with IC₅₀ ranging from 1.6 μM to 6.3 μM with relatively low cytotoxicity against normal epithelial breast cell line fR-2 and human embryonic kidney cell line HEK-293. Minimal hemolytic activity was observed for BG6 against human erythrocytes. Peptide BG6 displayed anti-migratory and anti-invasive potentials showing strong interactions with intrinsic apoptotic markers Bcl-2, Bax, and cleaved-PARP, as well as the induction of the mitochondria maladjustment mediated apoptosis.

Hormesis and Oxidative Distress: Pathophysiology of Reactive Oxygen Species and the Open Question of Antioxidant Modulation and Supplementation

Alterations of redox homeostasis leads to a condition of resilience known as hormesis that is due to the activation of redox-sensitive pathways stimulating cell proliferation, growth, differentiation, and angiogenesis. Instead, supraphysiological production of reactive oxygen species (ROS) exceeds antioxidant defence and leads to oxidative distress. This condition induces damage to biomolecules and is responsible or co-responsible for the onset of several chronic pathologies. Thus, a dietary antioxidant supplementation has been proposed in order to prevent aging, cardiovascular and degenerative diseases as well as carcinogenesis. However, this approach has failed to demonstrate efficacy, often leading to harmful side effects, in particular in patients affected by cancer. In this latter case, an approach based on endogenous antioxidant depletion, leading to ROS overproduction, has shown an interesting potential for enhancing susceptibility of patients to anticancer therapies. Therefore, a deep investigation of molecular pathways involved in redox balance is crucial in order to identify new molecular targets useful for the development of more effective therapeutic approaches. The review herein provides an overview of the pathophysiological role of ROS and focuses the attention on positive and negative aspects of antioxidant modulation with the intent to find new insights for a successful clinical application.

NOX2-mediated reactive oxygen species are double-edged swords in focal cerebral ischemia in mice

BACKGROUND

Reactive oxygen species (ROS) often promote acute brain injury after stroke, but their roles in the recovery phase have not been well studied. We tested the hypothesis that ROS activity mediated by NADPH oxidase 2 (NOX2) contributes to acute brain injury but promotes functional recovery during the delayed phase, which is linked with neuroinflammation, autophagy, angiogenesis, and the PI3K/Akt signaling pathway.

METHODS

We used the NOX2 inhibitor apocynin to study the role of NOX2 in brain injury and functional recovery in a middle cerebral artery occlusion (MCAO) stroke mouse model. Infarct size, neurological deficits and behavior were evaluated on days 3, 7, 10 and 14 after reperfusion. In addition, dynamic NOX2-induced ROS levels were measured by dihydroethidium (DHE) staining. Autophagy, inflammasomes, and angiogenesis were measured by immunofluorescence staining and western blotting. RNA sequencing was performed, and bioinformatics technology was used to analyze differentially expressed genes (DEGs), as well as the enrichment of biological functions and signaling pathways in ischemia penumbra at 7 days after reperfusion. Then, Akt pathway-related proteins were further evaluated by western blotting.

RESULTS

Our results showed that apocynin injection attenuated infarct size and mortality 3 days after stroke but promoted mortality and blocked functional recovery from 5 to 14 days after stroke. DHE staining showed that ROS levels were increased at 3 days after reperfusion and then gradually declined in WT mice, and these levels were significantly reduced by the NOX2 inhibitor apocynin. RNA-Seq analysis indicated that apocynin activated the immune response under hypoxic conditions. The immunofluorescence and western blot results demonstrated that apocynin inhibited the NLRP3 inflammasome and promoted angiogenesis at 3 days but promoted the NLRP3 inflammasome and inhibited angiogenesis at 7 and 14 days after stroke, which was mediated by regulating autophagy activation. Furthermore, RNA-Seq and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated that apocynin injection resulted in PI3K-Akt signaling pathway enrichment after 7 days of MCAO. We then used an animal model to show that apocynin decreased the protein levels of phosphorylated PI3K and Akt and NF-κB p65, confirming that the PI3K-Akt-NF-κB pathway is involved in apocynin-mediated activation of inflammation and inhibition of angiogenesis.

CONCLUSIONS

NOX2-induced ROS production is a double-edged sword that exacerbates brain injury in the acute phase but promotes functional recovery. This effect appears to be achieved by inhibiting NLRP3 inflammasome activation and promoting angiogenesis via autophagy activation.

Ononin Shows Anticancer Activity Against Laryngeal Cancer via the Inhibition of ERK/JNK/p38 Signaling Pathway

Background

Laryngeal cancer is a type of head and neck tumor with a poor prognosis and survival rate. The new cases of laryngeal cancer increased rapidly with a higher mortality rate around the world.

Objective

The current research work was focused to unveil the in vitro antitumor effects of ononin against the laryngeal cancer Hep-2 cells.

Methodology

The cytotoxic effects of ononin against the laryngeal cancer Hep-2 cells and normal HuLa-PC laryngeal cells were studied using an 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. The intracellular Reactive Oxygen Species (ROS) generation, apoptotic cell death, Mitochondrial Membrane Potential (MMP), and cell adhesion on the 25 and 50 µM ononin-treated Hep-2 cells were detected using respective staining assays. The levels of TBARS and antioxidants were assayed using specific kits. The expressions of c-Jun N-terminal kinase 1/2 (JNK1/2), Extracellular Signal-regulated Kinase 1/2 (ERK1/2), p38, Phosphatidylinositol-3 Kinase 1/2 (PI3K1/2), and protein kinase-B (Akt) in the ononin-treated Hep-2 cells were investigated using Reverse Transcription-Polymerase Chain Reaction (RT-PCR) assay.

Results

The ononin treatment effectively inhibited the Hep-2 cell viability but did not affect the viability of HuLa-PC cells. Furthermore, the ononin treatment effectively improved the intracellular ROS accumulation, depleted the MMP, and triggered apoptosis in Hep-2 cells. The Thiobarbituric acid reactive substances (TBARS) were improved, and Glutathione (GSH) levels and Superoxide dismutase (SOD) were depleted in the ononin-administered Hep-2 cells. The ononin treatment substantially inhibited the JNK/ERK/p38 axis in the Hep-2 cells.

Conclusion

Together, the outcomes of this exploration proved that the ononin has remarkable antitumor activity against laryngeal cancer Hep-2 cells.

Oxidative-Stress-Sensitive microRNAs in UV-Promoted Development of Melanoma

Simple Summary

Exposure to ultraviolet (UV) rays from the sun is one of the most important modifiable risk factors for skin cancer. Melanoma is the most life-threatening type of skin cancer. UV-induced DNA damage and oxidative stress represent two main mechanisms that, directly and indirectly, contribute to melanomagenesis. In addition, an interplay of abnormally expressed microRNAs (miRNAs) and redox imbalance is a hallmark in several cancers, including melanoma. UV radiation can be the central hub between these two cellular aberrations, as it is able to stimulate both. Here, to gain new mechanistic insights into melanomagenesis and identify new therapeutic targets for the prevention and treatment of melanoma, we report current evidence suggesting a complex interaction between UV-promoted deregulation of redox-sensitive miRNAs and known signal-transduction pathways underlying malignant transformation of melanocytes to melanoma.

Abstract

Melanoma is the most aggressive and life-threatening form of skin cancer. Key molecular events underlying the melanocytic transformation into malignant melanoma mainly involve gene mutations in which exposure to ultraviolet (UV) radiation plays a prominent role. However, several aspects of UV-induced melanomagenesis remain to be explored. Interestingly, redox-mediated signaling and perturbed microRNA (miRNA) profiles appear to be interconnected contributing factors able to act synergistically in melanoma initiation and progression. Since UV radiation can promote both redox imbalance and miRNA dysregulation, a harmful crosstalk between these two key cellular networks, with UV as central hub among them, is likely to occur in skin tissue. Therefore, decoding the complex circuits that orchestrate the interaction of UV exposure, oxidative stress, and dysregulated miRNA profiling can provide a deep understanding of the molecular basis of the melanomagenesis process. Furthermore, these mechanistic insights into the reciprocal regulation between these systems could have relevant implications for future therapeutic approaches aimed at counteracting UV-induced redox and miRNome imbalances for the prevention and treatment of malignant melanoma. In this review, we illustrate current information on the intricate connection between UV-induced dysregulation of redox-sensitive miRNAs and well-known signaling pathways involved in the malignant transformation of normal melanocytes to malignant melanoma.

Essential oil of Foeniculum vulgare subsp. piperitum fruits exerts an anti‑tumor effect in triple‑negative breast cancer cells

At present, the growing spread of tumor cases worldwide renders the research of new promising and selective anticancer drugs urgent. The biological action of extracts of medicinal plants or their essential oils (EOs) is an emerging field of interest, since they could comprise a rich source of phytochemicals that can prove promising. In the present study, the biological activity and mechanism of action of the EO of Foeniculum vulgare subsp. piperitum fruits (FVPEO) were investigated using MTT assays, morphological analyses and western blotting in MDA‑MB231 cells, a triple‑negative breast cancer cell line. The findings revealed that FVPEO could exert strong anticancer effects, causing a dose‑dependent inhibition of breast cancer MDA‑MB231 cell growth, accompanied with DNA condensation and fragmentation. The cytotoxic effect of FVPEO was counteracted by the addition of the antioxidant N‑acetylcysteine and was associated with a marked increase in reactive oxygen species and stress‑related proteins; such as manganese superoxide dismutase, c‑Jun, phospho‑c‑Jun N‑terminal kinase and nuclear factor E2‑related factor 2, and the latter's transcriptional targets, Heme oxygenase‑1 and NAD(P)H quinone oxidoreductase 1 (NQO1). As evidenced by the activation of caspase‑3 and fragmentation of poly(ADP‑ribose) polymerase‑1, which are typical apoptosis markers, FVPEO promoted apoptotic cell death accompanied with an increase in phosphorylated H2A histone family member X and the activation of the NQO1/p53 axis. In combination, the present experiments provided evidence that FVPEO could represent a reservoir of biologically active compounds suitable for both cancer prevention and treatment.

Algicidal Bacteria: A Review of Current Knowledge and Applications to Control Harmful Algal Blooms

Interactions between bacteria and phytoplankton in aqueous ecosystems are both complex and dynamic, with associations that range from mutualism to parasitism. This review focuses on algicidal interactions, in which bacteria are capable of controlling algal growth through physical association or the production of algicidal compounds. While there is some evidence for bacterial control of algal growth in the field, our understanding of these interactions is largely based on laboratory culture experiments. Here, the range of these algicidal interactions is discussed, including specificity of bacterial control, mechanisms for activity, and insights into the chemical and biochemical analysis of these interactions. The development of algicidal bacteria or compounds derived from bacteria for control of harmful algal blooms is reviewed with a focus on environmentally friendly or sustainable methods of application. Potential avenues for future research and further development and application of bacterial algicides for the control of algal blooms are presented.

Effects of H2O2 Treatment Combined With PI3K Inhibitor and MEK Inhibitor in AGS Cells: Oxidative Stress Outcomes in a Model of Gastric Cancer

Gastric cancer is worldwide the fifth and third cancer for incidence and mortality, respectively. Stomach wall is daily exposed to oxidative stress and BER system has a key role in the defense from oxidation-induced DNA damage, whilst ErbB receptors have important roles in the pathogenesis of cancer. We used AGS cells as an aggressive gastric carcinoma cell model, treated with H₂O₂ alone or combined with ErbB signaling pathway inhibitors, to evaluate the effects of oxidative stress in gastric cancer, focusing on the modulation of ErbB signaling pathways and their eventual cross-talk with BER system. We showed that treatment with H₂O₂ combined with PI3K/AKT and MEK inhibitors influenced cell morphology and resulted in a reduction of cancer cell viability. Migration ability was reduced after H₂O₂ treatment alone or combined with MEK inhibitor and after PI3K/AKT inhibitor alone. Western blotting analysis showed that oxidative stress stimulated EGFR pathway favoring the MAPKs activation at the expense of PI3K/AKT pathway. Gene expression analysis by RT-qPCR showed ErbB2 and OGG1 increase under oxidative stress conditions. Therefore, we suggest that in AGS cells a pro-oxidant treatment can reduce gastric cancer cell growth and migration via a different modulation of PI3K and MAPKs pathways. Moreover, the observed ErbB2 and OGG1 induction is a cellular response to protect the cells from H₂O₂-induced cell death. In conclusion, to tailor specific combinations of therapies and to decide which strategy to use, administration of a chemotherapy that increases intracellular ROS to toxic levels, might not only be dependent on the tumor type, but also on the molecular targeting therapy used.

Construction of a Redox-Related Prognostic Model with Predictive Value in Survival and Therapeutic Response for Patients with Lung Adenocarcinoma

Background

Lung adenocarcinoma (LUAD) represents the most common histological subtype of lung cancer. Redox plays a significant role in oncogenesis and antitumor immunity. In this study, we aimed to investigate the prognostic redox-associated genes and construct a redox-based prognostic signature for LUAD.

Materials and Methods

A discovery cohort containing 479 LUAD samples from The Cancer Genome Atlas (TCGA) was analyzed. We identified prognostic redox-associated genes by weighted correlation network analysis (WGCNA) and univariate Cox regression analysis to construct a prognostic model via least absolute shrinkage and selection operator (LASSO)-multivariate Cox regression analyses. The performance of the redox-based model was validated in the TCGA cohort and an independent cohort of 456 samples by Cox regression analyses, log-rank test, and receiver operating characteristic (ROC) curves. Correlations of the model with clinicopathological variables and lymphocyte infiltration were assessed. Gene set enrichment analysis (GSEA) was used to clarify the underlying mechanism of the prognostic model. We constructed a nomogram based on the model and created calibration curves to show the accordance between actual survival and predicted survival of the nomogram.

Results

Stepwise analyses identified 6 prognostic redox-associated genes of LUAD and constructed a prognostic model that performed well in both the discovery and validation cohorts. The model was found to be associated with tumor stage, mutation of TP53 and EGFR, and lymphocyte infiltration. The model was mainly involved in the regulation of the cell cycle, DNA replication and repair, NADH metabolism, and the p53 signaling pathway. Calibration curves showed the high predictive accuracy of the nomogram.

Conclusions

This study explored the role of redox-associated genes in LUAD and constructed a prognostic model of LUAD. The signature was also associated with tumor progression and therapeutic response to immunotherapy. These findings contributed to uncovering the underlying mechanism and discovering novel prognostic predictor of LUAD.

Parthenolide and Its Soluble Analogues: Multitasking Compounds with Antitumor Properties

Due to its chemical properties and multiple molecular effects on different tumor cell types, the sesquiterpene lactone parthenolide (PN) can be considered an effective drug with significant potential in cancer therapy. PN has been shown to induce either classic apoptosis or alternative caspase-independent forms of cell death in many tumor models. The therapeutical potential of PN has been increased by chemical design and synthesis of more soluble analogues including dimethylaminoparthenolide (DMAPT). This review focuses on the molecular mechanisms of both PN and analogues action in tumor models, highlighting their effects on gene expression, signal transduction and execution of different types of cell death. Recent findings indicate that these compounds not only inhibit prosurvival transcriptional factors such as NF-κB and STATs but can also determine the activation of specific death pathways, increasing intracellular reactive oxygen species (ROS) production and modifications of Bcl-2 family members. An intriguing property of these compounds is its specific targeting of cancer stem cells. The unusual actions of PN and its analogues make these agents good candidates for molecular targeted cancer therapy.

Astaxanthin induces NADPH oxidase activation and receptor‑interacting protein kinase 1‑mediated necroptosis in gastric cancer AGS cells

Astaxanthin (ASX), a red-colored xanthophyll carotenoid, functions as an antioxidant or pro-oxidant. ASX displays anticancer effects by reducing or increasing oxidative stress. Reactive oxygen species (ROS) promote cancer cell death by necroptosis mediated by receptor-interacting protein kinase 1 (RIP1) and RIP3. NADPH oxidase is a major source of ROS that may promote necroptosis in some cancer cells. The present study aimed to investigate whether ASX induces necroptosis by increasing NADPH oxidase activity and ROS levels in gastric cancer AGS cells. AGS cells were treated with ASX with or without ML171 (NADPH oxidase 1 specific inhibitor), N-acetyl cysteine (NAC; antioxidant), z-VAD (pan-caspase inhibitor) or Necrostatin-1 (Nec-1; a specific inhibitor of RIP1). As a result, ASX increased NADPH oxidase activity, ROS levels and cell death, and these effects were suppressed by ML171 and NAC. Furthermore, ASX induced RIP1 and RIP3 activation, ultimately inducing mixed lineage kinase domain-like protein (MLKL) activation, lactate dehydrogenase (LDH) release and cell death. Moreover, the ASX-induced decrease in cell viability was reversed by Nec-1 treatment and RIP1 siRNA transfection, but not by z-VAD. ASX did not increase the ratio of apoptotic Bax/anti-apoptotic Bcl-2, the number of Annexin V-positive cells, or caspase-9 activation, which are apoptosis indices. In conclusion, ASX induced necroptotic cell death by increasing NADPH oxidase activity, ROS levels, LDH release and the number of propidium iodide-positive cells, as well as activating necroptosis-regulating proteins, RIP1/RIP3/MLKL, in gastric cancer AGS cells. The results of this study demonstrated the necroptotic effect of ASX on gastric cancer AGS cells, which required NADPH oxidase activation and RIP1/RIP3/MLKL signaling in vitro.

The Good and Bad of Nrf2: An Update in Cancer and New Perspectives in COVID-19

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a well-known transcription factor best recognised as one of the main regulators of the oxidative stress response. Beyond playing a crucial role in cell defence by transactivating cytoprotective genes encoding antioxidant and detoxifying enzymes, Nrf2 is also implicated in a wide network regulating anti-inflammatory response and metabolic reprogramming. Such a broad spectrum of actions renders the factor a key regulator of cell fate and a strategic player in the control of cell transformation and response to viral infections. The Nrf2 protective roles in normal cells account for its anti-tumour and anti-viral functions. However, Nrf2 overstimulation often occurs in tumour cells and a complex correlation of Nrf2 with cancer initiation and progression has been widely described. Therefore, if on one hand, Nrf2 has a dual role in cancer, on the other hand, the factor seems to display a univocal function in preventing inflammation and cytokine storm that occur under viral infections, specifically in coronavirus disease 19 (COVID-19). In such a variegate context, the present review aims to dissect the roles of Nrf2 in both cancer and COVID-19, two widespread diseases that represent a cause of major concern today. In particular, the review describes the molecular aspects of Nrf2 signalling in both pathological situations and the most recent findings about the advantages of Nrf2 inhibition or activation as possible strategies for cancer and COVID-19 treatment respectively.

Redox Imbalance and Mitochondrial Release of Apoptogenic Factors at the Forefront of the Antitumor Action of Mango Peel Extract

Today, an improved understanding of cancer cell response to cellular stress has become more necessary. Indeed, targeting the intracellular pro-oxidant/antioxidant balance triggering the tumor commitment to cell demise could represent an advantageous strategy to develop cancer-tailored therapies. In this scenario, the present study shows how the peel extract of mango-a tropical fruit rich in phytochemicals with nutraceutical properties-can affect the cell viability of three colon cancer cell lines (HT29, Caco-2 and HCT116), inducing an imbalance of cellular redox responses. By using hydro-alcoholic mango peel extract (MPE), we observed a consistent decline in thiol group content, which was accompanied by upregulation of MnSOD-a mitochondrial scavenger enzyme that modulates the cellular response against oxidative damage. Such an effect was the consequence of an early production of mitochondrial superoxide anions that appeared after just 30 min of exposure of colon cancer cells to MPE. The effect was accompanied by mitochondrial injury, consisting of the dissipation of mitochondrial membrane potential and a decrease in the level of proteins localized in the mitochondrial membrane-such as voltage-dependent anion-selective channel (VDAC1), mitofilin, and some members of Bcl-2 family proteins (Mcl-1, Bcl-2 and Bcl-X_L)-with the mitochondrial release of apoptogenic factors (cytochrome C and AIF). The analysis of the cytotoxic effects exerted by the different constituents of MPE (gallic acid, mangiferin, citric acid, quinic acid, pentagalloyl glucose, and methyl gallate) allowed us to identify those phytochemicals responsible for the observed anticancer effects, sustaining their future employment as chemopreventive or therapeutic agents.

Current Strategies for Modulating Aβ Aggregation with Multifunctional Agents

Alzheimer's disease (AD), as the primary cause of dementia, has seriously affected millions of people worldwide and brought a very heavy financial and social burden. With the growth of population and aging, the situation will worsen unless efficacious drugs are found to reverse, stop, or even slow down disease progression. More and more evidence has demonstrated that amyloid-β (Aβ) aggregation is an upstream causative factor in AD pathogenesis and then triggers a slew of pathological events. Furthermore, the concentrated redox metal ions in the AD brain, especially Cu(II), can significantly exacerbate Aβ aggregation and contribute to the formation of neurotoxic reactive oxygen species (ROS). Therefore, the inhibition of Aβ aggregation and relief of amyloidosis-initiated neurotoxicity play a critical role in AD treatment. Until now, several methods have been proposed to modulate Aβ aggregation, such as developing aggregation inhibitors to interfere with Aβ assembly via noncovalent interactions, copper chelators to cut off metal-accelerated Aβ aggregation and concomitant cytotoxicity, photooxidation to reduce the hydrophobicity and aggregation tendency of Aβ, thermal dissociation to disrupt amyloid aggregates susceptible to temperature, degradation with artificial protease to fracture the Aβ peptide into small fragments, and the clearance of peripheral Aβ to bypass the obstruction of the BBB and reduce the Aβ burden.In this Account, we focus on our contributions to the development of Aβ-targeted multifunctional molecules and nanoparticles, emphasizing the diversified strategies and synergistic therapeutic effects. These therapeutic agents possess the following multifunctionalities: (1) compared with frequently used aggregation inhibitors restricted by intrinsically feeble and sensitive noncovalent interactions, multifunctional agents can efficiently block Aβ aggregation by exploiting two or more Aβ-specific inhibition strategies simultaneously; (2) apart from regulating Aβ aggregation, multipronged agents can also target and modulate other pathological factors in AD pathogenesis, such as increased oxidative stress, abnormal copper accumulation, and irreversible neuron loss; (3) multifunctional platforms with both diagnostic and therapeutic modalities through integrating in situ imaging, real-time diagnostics, a multitarget direction, stimuli-responsive drug release, and the blood-brain barrier (BBB) translocation features are instrumental in improving drug levels at trouble sites, diminishing off-target adverse reactions, evaluating therapeutic effects, and averting overtreatment.Given the fact that amyloid aggregation, local inflammation, and metal dyshomeostasis are universal biomarkers shared by various neurodegenerative disorders, this Account provides a perspective for the evolution of customized therapeutic agents with multiple reactivities for other neurodegenerative diseases. In addition, recent studies have indicated that Aβ aggregates can enter the nucleus and induce DNA damage and anomalous conformational transition. We also explore the influences of DNA on the biological effects of Aβ aggregates.

IκBα targeting promotes oxidative stress-dependent cell death

BACKGROUND

Oxidative stress is a hallmark of many cancers. The increment in reactive oxygen species (ROS), resulting from an increased mitochondrial respiration, is the major cause of oxidative stress. Cell fate is known to be intricately linked to the amount of ROS produced. The direct generation of ROS is also one of the mechanisms exploited by common anticancer therapies, such as chemotherapy.

METHODS

We assessed the role of NFKBIA with various approaches, including in silico analyses, RNA-silencing and xenotransplantation. Western blot analyses, immunohistochemistry and RT-qPCR were used to detect the expression of specific proteins and genes. Immunoprecipitation and pull-down experiments were used to evaluate protein-protein interactions.

RESULTS

Here, by using an in silico approach, following the identification of NFKBIA (the gene encoding IκBα) amplification in various cancers, we described an inverse correlation between IκBα, oxidative metabolism, and ROS production in lung cancer. Furthermore, we showed that novel IκBα targeting compounds combined with cisplatin treatment promote an increase in ROS beyond the tolerated threshold, thus causing death by oxytosis.

CONCLUSIONS

NFKBIA amplification and IκBα overexpression identify a unique cancer subtype associated with specific expression profile and metabolic signatures. Through p65-NFKB regulation, IκBα overexpression favors metabolic rewiring of cancer cells and distinct susceptibility to cisplatin. Lastly, we have developed a novel approach to disrupt IκBα/p65 interaction, restoring p65-mediated apoptotic responses to cisplatin due to mitochondria deregulation and ROS-production.

The Impact of Mitochondrial Fission-Stimulated ROS Production on Pro-Apoptotic Chemotherapy

Cancer is one of the world's deadliest afflictions. Despite recent advances in diagnostic and surgical technologies, as well as improved treatments of some individual tumor types, there is currently no universal cure to prevent or impede the uncontrolled proliferation of malignant cells. Targeting tumors by inducing apoptosis is one of the pillars of cancer treatment. Changes in mitochondrial morphology precede intrinsic apoptosis, but mitochondrial dynamics has only recently been recognized as a viable pharmacological target. In many cancers, oncogenic transformation is accompanied by accumulation of elevated cellular levels of ROS leading to redox imbalance. Hence, a common chemotherapeutic strategy against such tumor types involves deploying pro-oxidant agents to increase ROS levels above an apoptotic death-inducing threshold. The aim of this chapter is to investigate the benefit of stimulating mitochondrial fission-dependent production of ROS for enhanced killing of solid tumors. The main question to be addressed is whether a sudden and abrupt change in mitochondrial shape toward the fragmented phenotype can be pharmacologically harnessed to trigger a burst of mitochondrial ROS sufficient to initiate apoptosis specifically in cancer cells but not in non-transformed healthy tissues.

Anti-Stem Cell Property of Pterostilbene in Gastrointestinal Cancer Cells

Pterostilbene (PTE) is a natural sterbenoid contained in blueberries that has an antioxidant effect. In contrast, PTE also generates oxidative stress in cancer cells and provides an antitumor effect. Here, we examined the potential mechanism of this contrasting effect of PTE using three gastrointestinal cancer cell lines, namely CT26, HT29, and MKN74. PTE showed a dose-dependent inhibition of cell proliferation, sphere-forming ability, and stem cell marker expression in all three cell lines. Furthermore, the cells treated with PTE showed an increase in mitochondrial membrane potential and an increase in mitochondrial oxidative stress and lipid peroxide. Upon concurrent treatment with vitamin E, N-acetyl-L-cysteine, and PTE, the PTE-induced mitochondrial oxidative stress and growth inhibition were suppressed. These findings indicate that PTE induces oxidative stress in cancer cells, suppresses stemness, and inhibits proliferation. These antitumor effects of PTE are considered to be useful in cancer treatment.

Signal transducer and activator of transcription 3 mediates apoptosis inhibition through reducing mitochondrial ROS and activating Bcl-2 in gemcitabine-resistant lung cancer A549 cells

Lung cancer is a leading cause of cancer-related death worldwide. In this study, we used lung adenocarcinoma cells as a model, as lung adenocarcinoma has the highest mortality rate among all lung cancers. For the past few years, medical treatments or lung cancer have been limited because of chemotherapy resistance. Therefore, understanding the pathogenesis of the development of drug resistance in lung cancer is urgent. Gemcitabine is widely prescribed in the chemotherapeutic treatment of lung cancers. In this study, we developed gemcitabine-resistant lung adenocarcinoma cells (A549-GR) from the A549 cell line. The results showed that apoptotic protein expression and reactive oxygen species (ROS) generation were reduced in A549-GR cells compared to A549 cells. Interestingly, we found that signal transducer and activator of transcription 3 (STAT3) translocated to the nucleus and mitochondria to affect the apoptotic pathway and ROS generation, respectively. Furthermore, treatment with STAT3 small interfering RNA diminished the increase in ROS production, proliferation and antiapoptotic proteins in A549-GR cells. Taken together, the study demonstrated that STAT3 acts as an essential regulator and moderates apoptosis through two major mechanisms to induce gemcitabine resistance in cells; and these findings provide a potential target for the treatment of gemcitabine-resistant lung cancer.

Molecular Basis of Alzheimer's Disease: Focus on Mitochondria

Alzheimer's disease (AD) is a progressive neurodegenerative disease, characterized by memory loss and multiple cognitive impairments. With the increased aging population, AD is a major health concern in society. Morphological and pathological studies revealed that AD is associated with the loss of synapses, defective mitochondria, and the proliferation of reactive astrocytes and microglia, in addition to the presence amyloid-β and phosphorylated tau in learning and memory regions of the brain in AD patients. AD occurs in two forms: early-onset familial and late-onset sporadic. Genetic mutations in APP, PS1, and PS2 loci cause familial AD. Multiple factors are reported to be involved in late-onset AD, including APOE4 genotype, polymorphisms in several gene loci and type 2 diabetes, traumatic brain injury, stroke, and age-related factors, including increased reactive oxygen species production and dysfunction in mitochondria. It is widely accepted that synaptic damage and mitochondrial dysfunction are early events in disease process. The purpose of this article is to highlight molecular triggers to the disease process. This article also reviews factors, including age, gender, lifestyle, epigenetic factors, and type 2 diabetes, that are involved in late-onset AD. This article also discusses recent developments in research of mitochondrial structure, function, physiology, dynamics, biogenesis, mitophagy, and mitochondrial DNA changes in healthy and diseased states.

ROS-Dependent ER Stress and Autophagy Mediate the Anti-Tumor Effects of Tributyltin (IV) Ferulate in Colon Cancer Cells

Organotin compounds represent potential cancer therapeutics due to their pro-apoptotic action. We recently synthesized the novel organotin ferulic acid derivative tributyltin (IV) ferulate (TBT-F) and demonstrated that it displays anti-tumor properties in colon cancer cells related with autophagic cell death. The purpose of the present study was to elucidate the mechanism of TBT-F action in colon cancer cells. We specifically show that TBT-F-dependent autophagy is determined by a rapid generation of reactive oxygen species (ROS) and correlated with endoplasmic reticulum (ER) stress. TBT-F evoked nuclear factor erythroid-2 related factor 2 (Nrf2)-mediated antioxidant response and Nrf2 silencing by RNA interference markedly increased the anti-tumor efficacy of the compound. Moreover, as a consequence of ROS production, TBT-F increased the levels of glucose regulated protein 78 (Grp78) and C/EBP homologous protein (CHOP), two ER stress markers. Interestingly, Grp78 silencing produced significant decreasing effects on the levels of the autophagic proteins p62 and LC3-II, while only p62 decreased in CHOP-silenced cells. Taken together, these results indicate that ROS-dependent ER stress and autophagy play a major role in the TBT-F action mechanism in colon cancer cells and open a new perspective to consider the compound as a potential candidate for colon cancer treatment.

Enhanced lipid biosynthesis in human tumor-induced macrophages contributes to their protumoral characteristics

Background

Tumor-associated macrophages (TAMs) are key components of the tumor microenvironment (TME) in non-medullary thyroid carcinoma (TC) and neuroblastoma (NB), being associated with a poor prognosis for patients. However, little is known about how tumors steer the specific metabolic phenotype and function of TAMs.

Methods

In a human coculture model, transcriptome, metabolome and lipidome analysis were performed on TC-induced and NB-induced macrophages. The metabolic shift was correlated to functional readouts, such as cytokine production and reactive oxygen species (ROS) production, including pharmacological inhibition of metabolic pathways.

Results

Based on transcriptome and metabolome analysis, we observed a strong upregulation of lipid biosynthesis pathways in TAMs. Subsequently, lipidome analysis revealed that tumor-induced macrophages have an increased total lipid content and enriched levels of intracellular lipids, especially phosphoglycerides and sphingomyelins. Strikingly, this metabolic shift in lipid synthesis contributes to their protumoral functional characteristics: blocking key enzymes of lipid biosynthesis in the tumor-induced macrophages reversed the increased inflammatory cytokines and the capacity to produce ROS, two well-known protumoral factors in the TME.

Conclusions

Taken together, our data show that tumor cells can stimulate lipid biosynthesis in macrophages to induce protumoral cytokine and ROS responses and advocate lipid biosynthesis as a potential therapeutic target to reprogram the TME.

Imaging Hg2+-Induced Oxidative Stress by NIR Molecular Probe with "Dual-Key-and-Lock" Strategy

Mercury (Hg) is considered an extremely toxic heavy metal which is extremely harmful to both the human body and environment. In addition, Hg²⁺-induced oxidative stress also exerts a crucial role to play in pathophysiological mechanisms of mercury toxicity. Thus, efficient and specific fluorescent probes for imaging Hg²⁺-induced oxidative stress are necessary. In the present study, we rationally design a novel Hg²⁺-activated and ICT-based NIR emission fluorescent probe NIR-HO for sequentially monitoring the ONOO^- level with a "dual-key-and-lock" strategy. The probe NIR-HO showed rapid response and excellent specificity and sensitivity for the detection of Hg²⁺ and ONOO^- in vitro. Cell imaging demonstrated that Hg²⁺-induced oxidative stress was involved in ONOO^- upregulation. Also, GSH, NAC, and EDTA were employed as excellent detoxifying drugs against Hg²⁺-induced toxicity. Moreover, the probe NIR-HO was successfully used for imaging Hg²⁺ and ONOO^- in vivo. In brief, NIR-HO provides a simple and powerful approach which can be used to image Hg²⁺-induced oxidative stress in the pathological environment.

ROS-Mediated Therapeutic Strategy in Chemo-/Radiotherapy of Head and Neck Cancer

Head and neck cancer is a highly genetic and metabolic heterogeneous collection of malignancies of the lip, oral cavity, salivary glands, pharynx, esophagus, paranasal sinuses, and larynx with five-year survival rates ranging from 12% to 93%. Patients with head and neck cancer typically present with advanced stage III, IVa, or IVb disease and are treated with comprehensive modality including chemotherapy, radiotherapy, and surgery. Despite advancements in treatment modality and technique, noisome recurrence, invasiveness, and resistance as well as posttreatment complications severely influence survival rate and quality of life. Thus, new therapeutic strategies are urgently needed that offer enhanced efficacy with less toxicity. ROS in cancer cells plays a vital role in regulating cell death, DNA repair, stemness maintenance, metabolic reprogramming, and tumor microenvironment, all of which have been implicated in resistance to chemo-/radiotherapy of head and neck cancer. Adjusting ROS generation and elimination to reverse the resistance of cancer cells without impairing normal cells show great hope in improving the therapeutic efficacy of chemo-/radiotherapy of head and neck cancer. In the current review, we discuss the pivotal and targetable redox-regulating system including superoxide dismutases (SODs), tripeptide glutathione (GSH), thioredoxin (Trxs), peroxiredoxins (PRXs), nuclear factor erythroid 2-related factor 2/Kelch-like ECH-associated protein 1 (Nrf2/keap1), and mitochondria electron transporter chain (ETC) complexes and their roles in regulating ROS levels and their clinical significance implicated in chemo-/radiotherapy of head and neck cancer. We also summarize several old drugs (referred to as the non-anti-cancer drugs used in other diseases for a long time) and small molecular compounds as well as natural herbs which effectively modulate cellular ROS of head and neck cancer to synergize the efficacy of conventional chemo-/radiotherapy. Emerging interdisciplinary techniques including photodynamic, nanoparticle system, and Bio-Electro-Magnetic-Energy-Regulation (BEMER) therapy are promising measures to broaden the potency of ROS modulation for the benefit of chemo-/radiotherapy in head and neck cancer.

Brain Opioid Activity and Oxidative Injury: Different Molecular Scenarios Connecting Celiac Disease and Autistic Spectrum Disorder

Celiac Disease (CD) is an immune-mediated disease triggered by the ingestion of wheat gliadin and related prolamins from other cereals, such as barley and rye. Immunity against these cereal-derived proteins is mediated by pro-inflammatory cytokines produced by both innate and adaptive system response in individuals unable to adequately digest them. Peptides generated in this condition are absorbed across the gut barrier, which in these patients is characterized by the deregulation of its permeability. Here, we discuss a possible correlation between CD and Autistic Spectrum Disorder (ASD) pathogenesis. ASD can be induced by an excessive and inappropriate brain opioid activity during the neonatal period. Cereal-derived peptides produced in celiac patients cross the blood–brain barrier and bind to endogenous opioid receptors interfering with neurotransmission and generating deleterious effects on brain maturation, learning and social relations. Moreover, an increase in oxidative stress and a decrease in the antioxidant capacity, as well as an extended mitochondrial impairment in the brain, could represent a possible connection between ASD and CD. Therefore, we critically discuss the proposed relationship between ASD and CD and the possible usefulness of a gluten-free diet in ASD patients.

Reactive Oxygen Species and Antitumor Immunity-From Surveillance to Evasion

The immune system is a crucial regulator of tumor biology with the capacity to support or inhibit cancer development, growth, invasion and metastasis. Emerging evidence show that reactive oxygen species (ROS) are not only mediators of oxidative stress but also players of immune regulation in tumor development. This review intends to discuss the mechanism by which ROS can affect the anti-tumor immune response, with particular emphasis on their role on cancer antigenicity, immunogenicity and shaping of the tumor immune microenvironment. Given the complex role that ROS play in the dynamics of cancer-immune cell interaction, further investigation is needed for the development of effective strategies combining ROS manipulation and immunotherapies for cancer treatment.

Modulation of the tumor microenvironment by natural agents: implications for cancer prevention and therapy

The development of cancer is not just the growth and proliferation of a single transformed cell, but its surrounding environment also coevolves with it. Indeed, successful cancer progression depends on the ability of the tumor cells to develop a supportive tumor microenvironment consisting of various types of stromal cells. The interactions between the tumor and stromal cells are bidirectional and mediated through a variety of growth factors, cytokines, metabolites, and other biomolecules secreted by these cells. Tumor-stromal crosstalk creates optimal conditions for the tumor growth, metastasis, evasion of immune surveillance, and therapy resistance, and its targeting is being explored for clinical management of cancer. Natural agents from plants and marine life have been at the forefront of traditional medicine. Numerous epidemiological studies have reported the health benefits imparted on the consumption of certain fruits, vegetables, and their derived products. Indeed, a significant majority of anti-cancer drugs in clinical use are either naturally occurring compounds or their derivatives. In this review, we describe fundamental cellular and non-cellular components of the tumor microenvironment and discuss the significance of natural compounds in their targeting. Existing literature provides hope that novel prevention and therapeutic approaches will emerge from ongoing scientific efforts leading to the reduced tumor burden and improve clinical outcomes in cancer patients.

Non-redox cycling mechanisms of oxidative stress induced by PM metals

Metallic compounds contribute to the oxidative stress of ambient particulate matter (PM) exposure. The toxicity of redox inert ions of cadmium, mercury, lead and zinc, as well as redox-active ions of vanadium and chromium is underlain by dysregulation of mitochondrial function and loss of signaling quiescence. Central to the initiation of these effects is the interaction of metal ions with cysteinyl thiols on glutathione and key regulatory proteins, which leads to impaired mitochondrial electron transport and persistent pan-activation of signal transduction pathways. The mitochondrial and signaling effects are linked by the production of H₂O₂, generated from mitochondrial superoxide anion or through the activation of NADPH oxidase, which extends the range and amplifies the magnitude of the oxidative effects of the metals. This oxidative burden can be further potentiated by inhibitory effects of the metals on the enzymes of the glutathione and thioredoxin systems. Along with the better-known Fenton-based mechanisms, the non-redox cycling mechanisms of oxidative stress induced by metals constitute significant pathways for cellular injury induced by PM inhalation.

Identification of an Apis cerana cerana MAP kinase phosphatase 3 gene (AccMKP3) in response to environmental stress

MAP kinase phosphatase 3 (MKP3), a member of the dual-specificity protein phosphatase (DUSP) superfamily, has been widely studied for its role in development, cancer, and environmental stress in many organisms. However, the functions of MKP3 in various insects have not been well studied, including honeybees. In this study, we isolated an MKP3 gene from Apis cerana cerana and explored the role of this gene in the resistance to oxidation. We found that AccMKP3 is highly conserved in different species and shares the closest evolutionary relationship with AmMKP3. We determined the expression patterns of AccMKP3 under various stresses. qRT-PCR results showed that AccMKP3 was highly expressed during the pupal stages and in adult muscles. We further found that AccMKP3 was induced in all the stress treatments. Moreover, we discovered that the enzymatic activities of peroxidase, superoxide dismutase, and catalase increased and that the expression levels of several antioxidant genes were affected after AccMKP3 was knocked down. Collectively, these results suggest that AccMKP3 may be associated with antioxidant processes involved in response to various environmental stresses.

The Anti-Cancer Effect of Mangifera indica L. Peel Extract is Associated to γH2AX-mediated Apoptosis in Colon Cancer Cells

Ethanolic extracts from Mangifera indica L. have been proved to possess anti-tumor properties in many cancer systems. However, although most effects have been demonstrated with fruit pulp extract, the underlying molecular mechanisms of mango peel are still unclear. This study was designed to explore the effects of mango peel extract (MPE) on colon cancer cell lines. MPE affected cell viability and inhibited the colony formation trend of tumor cells, while no effects were observed in human dermal fibroblasts used as a non-cancerous cell line model. These events were a consequence of the induction of apoptosis associated to reactive oxygen species (ROS) production, activation of players of the oxidative response such as JNK and ERK1/2, and the increase in Nrf2 and manganese superoxide dismutase (MnSOD). Significantly, mango peel-activated stress triggered a DNA damage response evidenced by the precocious phosphorylation of histone 2AX (γH2AX), as well as phosphorylated Ataxia telangiectasia-mutated (ATM) kinase and p53 upregulation. Mango peel extract was also characterized, and HPLC/MS (High Performance Liquid Chromatography/Mass Spectrometry) analysis unveiled the presence of some phenolic compounds that could be responsible for the anti-cancer effects. Collectively, these findings point out the importance of the genotoxic stress signaling pathway mediated by γH2AX in targeting colon tumor cells to apoptosis.

Selenocoumarins as new multitarget antiproliferative agents: Synthesis, biological evaluation and in silico calculations

Herein we report a straightforward preparation of new antiproliferative agents based on the hybridization of a coumarin skeleton and an organoselenium motif. Three families were obtained: isoselenocyanate, selenocarbamates and selenoureas. The main purpose of these hybrid structures is the development of new antiproliferative agents with a multitarget mode of action. A strong correlation between the nature of the organosenium scaffold and the antiproliferative activity was observed. Thus, whereas selenocarbamates proved to be inactive, or moderate antiproliferative agents, isoselenocyanate and most of the selenoureas behaved as strong antiproliferative agents, with GI₅₀ values within the low micromolar range. Interestingly, a good selectivity toward tumor cell lines was found for some of the compounds. Moreover, an increase in the ROS level was observed for tumor cells, and accordingly, these pro-oxidant species might be involved in their mode of action. Overall, title compounds were found not to be substrates for P-glycoprotein, which is overexpressed in many cancer cells as a way of detoxification, and thus, to develop drug resistance. In silico calculations revealed that the selenoderivatives prepared herein might undergo a strong interaction with the active site of HDAC8, and therefore, be potential inhibitors of histone deacetylase 8. In vitro assessment against HDAC8 revealed a strong inhibition of such enzyme exerted by selenoureas, particularly by symmetrical coumarin-containing selenourea. Two compounds showed good antiproliferative data and appear as plausible leads for further testings. The symmetrical coumarin 6 displays the best in vitro inhibition of HDAC8, but is affected by P-gp. In contrast, the N-butyl selenourea coumarin derivative 5a escapes P-gp resistance but has lower HDAC8 inhibition activity.

Ethanol-Mediated Stress Promotes Autophagic Survival and Aggressiveness of Colon Cancer Cells via Activation of Nrf2/HO-1 Pathway

Epidemiological studies suggest that chronic alcohol consumption is a lifestyle risk factor strongly associated with colorectal cancer development and progression. The aim of the present study was to examine the effect of ethanol (EtOH) on survival and progression of three different colon cancer cell lines (HCT116, HT29, and Caco-2). Our data showed that EtOH induces oxidative and endoplasmic reticulum (ER) stress, as demonstrated by reactive oxygen species (ROS) and ER stress markers Grp78, ATF6, PERK and, CHOP increase. Moreover, EtOH triggers an autophagic response which is accompanied by the upregulation of beclin, LC3-II, ATG7, and p62 proteins. The addition of the antioxidant N-acetylcysteine significantly prevents autophagy, suggesting that autophagy is triggered by oxidative stress as a prosurvival response. EtOH treatment also upregulates the antioxidant enzymes SOD, catalase, and heme oxygenase (HO-1) and promotes the nuclear translocation of both Nrf2 and HO-1. Interestingly, EtOH also upregulates the levels of matrix metalloproteases (MMP2 and MMP9) and VEGF. Nrf2 silencing or preventing HO-1 nuclear translocation by the protease inhibitor E64d abrogates the EtOH-induced increase in the antioxidant enzyme levels as well as the migration markers. Taken together, our results suggest that EtOH mediates both the activation of Nrf2 and HO-1 to sustain colon cancer cell survival, thus leading to the acquisition of a more aggressive phenotype.

Small molecules as therapeutic drugs for Alzheimer's disease

Mitochondrial dysfunction is a central protagonist of Alzheimer's disease (AD) pathogenesis. Mitochondrial dysfunction stems from various factors including mitochondrial DNA damage and oxidative stress from reactive oxygen species, membrane and ionic gradient destabilization, and interaction with toxic proteins such as amyloid beta (Aβ). Therapeutic drugs such as cholinesterase and glutamate inhibitors have proven to improve synaptic neurotransmitters, but do not address mitochondrial dysfunction. Researchers have demonstrated that oxidative damage may be reduced by increasing endogenous antioxidants, and/or increasing exogenous antioxidants such as vitamin C & E, beta-carotene and glutathione. Nonetheless, as AD pathology intensifies, endogenous antioxidants are overwhelmed, and exogenous antioxidants are unable to reach neuronal mitochondria as they are blocked by the blood brain barrier. Current therapeutic methods however include novel usage of lipophilic phosphonium cation bound to antioxidants, to effect neuronal mitochondria targeted activity. Mitochondria targeted MitoQ, MitoVitE, MitoTempo, MitoPBN and MCAT concentrate within mitochondria where they scavenge free-radicals, and augment mitochondrial dysfunction. Additional molecules include Szeto-Schiller (SS) peptides which target stability of the inner mitochondrial membrane, and DDQ molecule capable of improving bioenergetics and reduce mitochondrial fragmentation. This article discusses advantages and disadvantages of small molecules, their ability to mitigate Aβ induced damage, and ability to ameliorate synaptic dysfunction and cognitive loss.

Sub-lethal Doses of Polybrominated Diphenyl Ethers, in Vitro, Promote Oxidative Stress and Modulate Molecular Markers Related to Cell Cycle, Antioxidant Balance and Cellular Energy Management

In the present study, we evaluated the effects of different concentrations of the polybrominated diphenyl ethers (PBDEs) BDE-209, BDE-47 and BDE-99, on the vitality and oxidative stress of a HS-68 human cell culture exposed to the compounds for three days. The results showed that for this exposure time, only the highest concentrations produced a significant vitality reduction and oxidative stress induction (p < 0.05), measured as reactive oxygen species (ROS). Subsequently, in order to verify the effects of sub-lethal doses, cells were exposed for a longer time and data collected, after 12 and 20 days, to study ROS production and some molecular markers related to cell cycle and stress (p53, pRB, PARP, c-Jun and c-Fos), antioxidant status and proliferation (ERK, c-Jun and c-Fos), energy balance (NRF2, AMPK, HIF). Most of the biomarkers were influenced by the treatments, indicating that sub-lethal doses of PBDEs, for longer time, can enhance the production of ROS, altering the energetic metabolism, cell cycle and antioxidant balance, determining possible negative effects on the cell proliferation equilibrium.

A large pooled analysis refines gene expression-based molecular subclasses in cutaneous melanoma

This study aimed to establish the number of expression-based molecular subclasses in cutaneous melanoma, identify their dominant biological pathways and evaluate their clinical relevance. To this end, consensus clustering was performed separately on two independent datasets (n = 405 and n = 473) composed of publicly available cutaneous melanoma expression profiles from previous studies. Four expression-based molecular subclasses were identified and labelled ‘Oxidative phosphorylation’, ‘Oestrogen response/p53-pathway’, ‘Immune’ and ‘Cell cycle’, based on their dominantly expressed biological pathways determined by gene set enrichment analysis. Multivariate survival analysis revealed shorter overall survival in the ‘Oxidative phosphorylation’ subclass compared to the other subclasses. This was validated in a third independent dataset (n = 214). Finally, in a pooled cohort of 76 patients treated with anti-PD-1 therapy a trend towards a difference in response rates between subclasses was observed (‘Immune’ subclass: 65% responders, ‘Oxidative Phosphorylation’ subclass: 60% responders, other subclasses: <50% responders). These findings support the stratification of cutaneous melanoma in four expression-based molecular subclasses.

The relationships between cytochromes P450 and H2O2: Production, reaction, and inhibition

In this review we address the relationship between cytochromes P450 (P450) and H2O2. This association can affect biology in three distinct ways. First, P450s produce H2O2 as a byproduct either during catalysis or when no substrate is present. This reaction, known as uncoupling, releases reactive oxygen species that may have implications in disease. Second, H2O2 is used as an oxygen-donating co-substrate in peroxygenase and peroxidase reactions catalyzed by P450s. This activity has proven to be important mainly in reactions involving prokaryotic P450s, and investigators have harnessed this reaction with the aim of adaptation for industrial use. Third, H2O2-dependent inhibition of human P450s has been studied in our laboratory, demonstrating heme destruction and also the inactivating oxidation of the heme-thiolate ligand to a sulfenic acid (-SOH). This reversible oxidative modification of P450s may have implications in the prevention of uncoupling and may give new insights into the oxidative regulation of these enzymes. Research has elucidated many of the chemical mechanisms involved in the relationship between P450 and H2O2, but the application to biology is difficult to evaluate. Further studies are needed reveal both the harmful and protective natures of reactive oxygen species in an organismal context.

Reactive Chemicals and Electrophilic Stress in Cancer: A Minireview

Exogenous reactive chemicals can impair cellular homeostasis and are often associated with the development of cancer. Significant progress has been achieved by studying the macromolecular interactions of chemicals that possess various electron-withdrawing groups and the elucidation of the protective responses of cells to chemical interventions. However, the formation of electrophilic species inside the cell and the relationship between oxydative and electrophilic stress remain largely unclear. Derivatives of nitro-benzoxadiazole (also referred as nitro-benzofurazan) are potent producers of hydrogen peroxide and have been used as a model to study the generation of reactive species in cancer cells. This survey highlights the pivotal role of Cu/Zn superoxide dismutase 1 (SOD1) in the production of reactive oxygen and electrophilic species in cells exposed to cell-permeable chemicals. Lipophilic electrophiles rapidly bind to SOD1 and induce stable and functionally active dimers, which produce excess hydrogen peroxide leading to aberrant cell signalling. Moreover, reactive oxygen species and reactive electrophilic species, simultaneously generated by redox reactions, behave as independent entities that attack a variety of proteins. It is postulated that the binding of the electrophilic moiety to multiple proteins leading to impairing different cellular functions may explain unpredictable side effects in patients undergoing chemotherapy with reactive oxygen species (ROS)-inducing drugs. The identification of proteins susceptible to electrophiles at early steps of oxidative and electrophilic stress is a promising way to offer rational strategies for dealing with stress-related malignant tumors.