Helicobacter pylori infection promotes autophagy through Nrf2-mediated heme oxygenase upregulation in human gastric cancer cells

Nrf2: A critical participant in regulation of apoptosis, ferroptosis, and autophagy in gastric cancer

Nuclear factor erythroid 2-related factor-2 (Nrf2) is a specific transcription factor that maintains redox homeostasis by regulating the expression of anti-oxidative stress-related genes. Hyperactivation of Nrf2 is involved in tumor progression and is associated with chemoresistance in a large number of solid tumors. Programmatic cell death (PCD), such as apoptosis, ferroptosis, and autophagy, plays a crucial role in tumor development and chemotherapy sensitivity. Accumulating evidence suggests that some anti-tumor compounds and genes can induce massive production of reactive oxygen species (ROS) via inhibiting Nrf2 expression, which exacerbates oxidative stress and promotes Gastric cancer (GC) cell death, thereby enhancing the sensitivity of GC cells to chemotherapy-induced PCD. In this review, we summarize the role of antitumor drugs in interfering in three different types of PCD (apoptosis, ferroptosis, and autophagy) in GC cells by modulating Nrf2 expression, as well as the molecular mechanisms through which targeting Nrf2 brings about PCD and chemosensitivity. It is reasonable to believe that Nrf2 serves as a potential therapeutic target, and targeting Nrf2 by drug or gene regulation could provide a new strategy for the treatment of GC.

Nrf2 in human cancers: biological significance and therapeutic potential

The nuclear factor-erythroid 2-related factor 2 (Nrf2) is able to control the redox balance in the cells responding to oxidative damage and other stress signals. The Nrf2 upregulation can elevate the levels of antioxidant enzymes to support against damage and death. In spite of protective function of Nrf2 in the physiological conditions, the stimulation of Nrf2 in the cancer has been in favour of tumorigenesis. Since the dysregulation of molecular pathways and mutations/deletions are common in tumors, Nrf2 can be a promising therapeutic target. The Nrf2 overexpression can prevent cell death in tumor and by increasing the survival rate of cancer cells, ensures the carcinogenesis. Moreover, the induction of Nrf2 can promote the invasion and metastasis of tumor cells. The Nrf2 upregulation stimulates EMT to increase cancer metastasis. Furthermore, regarding the protective function of Nrf2, its stimulation triggers chemoresistance. The natural products can regulate Nrf2 in the cancer therapy and reverse drug resistance. Moreover, nanostructures can specifically target Nrf2 signaling in cancer therapy. The current review discusses the potential function of Nrf2 in the proliferation, metastasis and drug resistance. Then, the capacity of natural products and nanostructures for suppressing Nrf2-mediated cancer progression is discussed.

Vorinostat Treatment of Gastric Cancer Cells Leads to ROS-Induced Cell Inhibition and a Complex Pattern of Molecular Alterations in Nrf2-Dependent Genes

Histone deacetylase inhibitors (HDACi) show high antineoplastic potential in preclinical studies in various solid tumors, including gastric carcinoma; however, their use in clinical studies has not yet yielded convincing efficacies. Thus, further studies on cellular/molecular effects of HDACi are needed, for improving clinical efficacy and identifying suitable combination partners. Here, we investigated the role of oxidative stress in gastric cancer cells upon treatment with HDACi. A particular focus was laid on the role of the Nrf2 pathway, which can mediate resistance to cell-inhibitory effects of reactive oxidative species (ROS). Using fluorescence-based ROS sensors, oxidative stress was measured in human gastric cancer cell lines. Activation of the Nrf2 pathway was monitored in luciferase reporter assays as well as by mRNA and proteomic expression analyses of Nrf2 regulators and Nrf2-induced genes. Furthermore, the effects of ROS scavenger N-acetyl-L-cysteine (NAC) and Nrf2-knockdown on HDACi-dependent antiproliferative effects were investigated in colorimetric formazan-based and clonogenic survival assays. HDACi treatment led to increased oxidative stress levels and consequently, treatment with NAC reduced cytotoxicity of HDACi. In addition, vorinostat treatment stimulated expression of a luciferase reporter under the control of an antioxidative response element, indicating activation of the Nrf2 system. This Nrf2 activation was only partially reversible by treatment with NAC, suggesting ROS independent pathways to contribute to HDACi-promoted Nrf2 activation. In line with its cytoprotective role, Nrf2 knockdown led to a sensitization against HDACi. Accordingly, the expression of antioxidant and detoxifying Nrf2 target genes was upregulated upon HDACi treatment. In conclusion, oxidative stress induction upon HDAC inhibition contributes to the antitumor effects of HDAC inhibitors, and activation of Nrf2 represents a potentially important adaptive response of gastric cancer cells in this context.

Programmed cell death in Helicobacter pylori infection and related gastric cancer

Programmed cell death (PCD) plays a crucial role in maintaining the normal structure and function of the digestive tract in the body. Infection with Helicobacter pylori (H. pylori) is an important factor leading to gastric damage, promoting the Correa cascade and accelerating the transition from gastritis to gastric cancer. Recent research has shown that several PCD signaling pathways are abnormally activated during H. pylori infection, and the dysfunction of PCD is thought to contribute to the development of gastric cancer and interfere with treatment. With the deepening of studies on H. pylori infection in terms of PCD, exploring the interaction mechanisms between H. pylori and the body in different PCD pathways may become an important research direction for the future treatment of H. pylori infection and H. pylori-related gastric cancer. In addition, biologically active compounds that can inhibit or induce PCD may serve as key elements for the treatment of this disease. In this review, we briefly describe the process of PCD, discuss the interaction between different PCD signaling pathways and the mechanisms of H. pylori infection or H. pylori-related gastric cancer, and summarize the active molecules that may play a therapeutic role in each PCD pathway during this process, with the expectation of providing a more comprehensive understanding of the role of PCD in H. pylori infection.

Energy metabolism: a new target for gastric cancer treatment

Gastric cancer is the fifth most common malignancy worldwide having the fourth highest mortality rate. Energy metabolism is key and closely linked to tumour development. Most important in the reprogramming of cancer metabolism is the Warburg effect, which suggests that tumour cells will utilise glycolysis even with normal oxygen levels. Various molecules exert their effects by acting on enzymes in the glycolytic pathway, integral to glycolysis. Second, mitochondrial abnormalities in the reprogramming of energy metabolism, with consequences for glutamine metabolism, the tricarboxylic acid cycle and oxidative phosphorylation, abnormal fatty acid oxidation and plasma lipoprotein metabolism are important components of tumour metabolism. Third, inflammation-induced oxidative stress is a danger signal for cancer. Fourth, patterns of signalling pathways involve all aspects of metabolic transduction, and many clinical drugs exert their anticancer effects through energy metabolic signalling. This review summarises research on energy metabolism genes, enzymes and proteins and transduction pathways associated with gastric cancer, and discusses the mechanisms affecting their effects on postoperative treatment resistance and prognoses of gastric cancer. We believe that an in-depth understanding of energy metabolism reprogramming will aid the diagnosis and subsequent treatment of gastric cancer.

Cross-talk between Helicobacter pylori and gastric cancer: a scientometric analysis

Background

Helicobacter pylori (HP) is considered a leading risk factor for gastric cancer (GC). The aim of this article is to conduct bibliometric and visual analysis to assess scientific output, identify highly cited papers, summarize current knowledge, and explore recent hotspots and trends in HP/GC research.

Methods

A bibliographic search was conducted on October 24, 2023, to retrieve relevant studies on HP/GC research between 2003 and 2022. The search terms were attached to HP and GC. The main data were from the Web of Science Core Collection (WoSCC). Data visualization was performed using Biblioshiny, VOSviewer, and Microsoft Excel.

Results

In HP/GC research, 1970 papers were retrieved. The total number of papers (Np) in HP/GC was growing from 2003 to 2022. China and Japan were in the leading position and made the most contributions to HP/GC. Vanderbilt University and the US Department of Veterans Affairs had the highest Np. The most productive authors were Peek Jr Richard M. and Piazuelo M Blanca. Helicobacter received the most Np, while Gastroenterology had the most total citations (TC). High-cited publications and keyword clustering were used to identify the current status and trends in HP/GC research, while historical citation analysis provided insight into the evolution of HP/GC research. The hot topics included the effect of HP on gastric tumorigenesis and progression, the pathogenesis of HP-induced GC (HP factors), and the mechanisms by which HP affects GC (host factors). Research in the coming years could focus on topics such as autophagy, gut microbiota, immunotherapy, exosomes, epithelial-mesenchymal transition (EMT), and gamma-glutamyl transpeptidase (GGT).

Conclusion

This study evaluated the global scientific output in HP/GC research and its quantitative characteristics, identified the essential works, and collected information on the current status, main focuses and emerging trends in HP/GC research to provide academics with guidance for future paths.

The interaction between autophagy, Helicobacter pylori, and gut microbiota in gastric carcinogenesis

Chronic infection with Helicobacter pylori is the primary risk factor for the development of gastric cancer. Hindering our ability to comprehend the precise role of autophagy during H. pylori infection is the complexity of context-dependent autophagy signaling pathways. Recent and ongoing progress in understanding H. pylori virulence allows new frontiers of research for the crosstalk between autophagy and H. pylori. Novel approaches toward discovering autophagy signaling networks have further revealed their critical influence on the structure of gut microbiota and the metabolome. Here we intend to present a holistic view of the perplexing role of autophagy in H. pylori pathogenesis and carcinogenesis. We also discuss the intermediate role of autophagy in H. pylori-mediated modification of gut inflammatory responses and microbiota structure.

Helicobacter pylori infection induces autophagy via ILK regulation of NOXs-ROS-Nrf2/HO-1-ROS loop

Reactive oxygen species (ROS) can regulate the occurrence of autophagy, and effective control of the balance between ROS and autophagy may be an important strategy for Helicobacter pylori induced gastric-related diseases. In this study, infection with H. pylori led to a lower level of ILK phosphorylation and increased ROS generation. Knockdown of ILK enhanced total ROS generation, and upregulated NADPH oxidase (NOX) subunit p22-phox levels. Inhibition of NOXs affected total ROS generation. The inhibition of NOX and ROS generation reduced Nrf2 and HO-1 levels, and knockdown of ILK significantly enhanced Nrf2 levels in H. pylori-infected GES-1 cells. Activation of Nrf2 by DMF decreased ROS levels. Therefore, NOX-dependent ROS production regulated by ILK was essential for activation of Nrf2/HO-1 signaling pathways in H. pylori-infected GES-1 cells. Beclin1, ATG5 and LC3B-II levels were higher both in H. pylori-infected and ILK-knockdown GES-1 cells. In NAC-pretreated GES-1 cells infected with H. pylori, the LC3B-II level was decreased compared to that in cells after H. pylori infection alone. Stable low expression of ILK with further knockdown of Beclin1 or ATG5 significantly reduced LC3B-II levels in GES-1 cells, while with the addition of the autophagy inhibitor chloroquine (CQ), LC3B-II and p62 protein levels were both remarkably upregulated. H. pylori accelerated the accumulation of ROS and further led to the induction of ROS-mediated autophagy by inhibiting ILK levels. Together, these results indicate that H. pylori infection manipulates the NOX-ROS-Nrf2/HO-1-ROS loop to control intracellular oxygen stress and further induced ROS-mediated autophagy by inhibiting ILK levels.

Involvement of Nrf2 in the immune regulation of Litopenaeus vannamei against Vibrio harveyi infection

NF-E2-related factor-like-2 (Nrf2) is a transcription factor that belongs to the Cap'n'Collar transcription factor family and plays a role in regulating inflammation, autophagy, metabolism, proteostasis, and cancer prevention. However, its influence on Vibrio spp infection in L. vannamei remains uncertain. In this study, the effects of Nrf2 on the immune response in Vibrio spp infection was determined by RT-PCR and histopathological analysis. The results showed that RNAi of Nrf2 significantly decreased the expression of antioxidant-related genes (CAT, SOD and GST; p < 0.05), and significantly up-regulated inflammation-related genes (IMD, pro-PO, P38, Toll, Hsp70, NFκB and RAB6A; p < 0.05) and the apoptosis gene (caspase3). Under the infection of V. harveyi, histopathological analysis showed that after RNAi of Nrf2, the hepatopancreas of shrimp has an abnormal arrangement of hepatic tubules and vacuolization of hepatocyte; The basement membrane is peeled off and the epithelial cells are massively necrotic. Compared with the RNAi of Nrf2 group, the tissue damage in the SFN group was much lessened, and there were fewer apoptosis signals in the TUNEL assay. In conclusion, this experiment indicated that Nrf2 is involved in the regulation of inflammatory response, oxidative stress,and apoptosis induced by V. harveyi in L. vannamei.

6'-O-Galloylpaeoniflorin attenuates Helicobacter pylori-associated gastritis via modulating Nrf2 pathway

As a common disease of the digestive system, chronic gastritis is inflammation of the gastric mucosa caused by various factors. Helicobacter pylori (H. pylori) is one of the main causes of chronic gastritis, which can lead to gastric mucosal damage and gland atrophy, thereby promoting gastrocarcinogenesis. Oxidative stress and the inflammatory response are important mechanisms of H. pylori-induced gastritis. 6'-O-Galloylpaeoniflorin (GPF) is a substance isolated from peony root with antioxidant and anti-inflammatory activities. However, its role and mechanism in the pathogenesis of H. pylori-induced chronic gastritis remain unclear. This study explored the effects of GPF on H. pylori-induced gastric mucosal oxidative stress and inflammation using flow cytometry, western blotting, real-time quantitative PCR, and immunohistochemistry. We found that H. pylori infection increased oxidative stress and expression of inflammatory cytokines in vitro and in vivo and that these outcomes were inhibited by GPF. Furthermore, GPF activated nuclear factor erythroid-related factor-2 (Nrf2) and its downstream target genes in H. pylori-infected GES-1 cells and mice. The anti-inflammatory and antioxidant effects of GPF on H. pylori-infected cells were attenuated by an Nrf2 inhibitor. Taken together, these data suggest that GPF reduces H. pylori-induced gastric mucosa injury by activating Nrf2 signaling and that GPF is a potential candidate for the treatment of H. pylori-associated gastritis.

Overexpressed mitogen-and stress-activated protein kinase 1 promotes the resistance of cytarabine in acute myeloid leukemia through brahma related gene 1-mediated upregulation of heme oxygenase-1

Drug resistance remains a major challenge in the current treatment of acute myeloid leukemia (AML). Finding specific molecules responsible for mediating drug resistance in AML contributes to the effective reversal of drug resistance. Recent studies have found that mitogen- and stress-activated protein kinase 1 (MSK1) is of great significance in the occurrence and development of tumors. In the current study, MSK1 was found highly expressed in drug-resistant AML patients. Heme oxygenase-1 (HO-1) has been previously validated to be associated with drug resistance in AML. Our study revealed a positive correlation between MSK1 and HO-1 in patient samples. In vitro experiments revealed that the sensitivity of AML cell lines THP-1 and U937 to cytarabine (Ara-C) significantly decreased after overexpression of MSK1. Meanwhile, downregulation of MSK1 by siRNA transfection or treatment of pharmacological inhibitor SB-747651A in AML cell lines and primary AML cells enhanced the sensitivity to Ara-C. Flow cytometry analysis showed that downregulation of MSK1 in AML cells accelerated apoptosis and arrested cell cycle progression in G0/G1 phase. However, the increased cell sensitivity induced by MSK1 downregulation was reversed by the induction of HO-1 inducer Hemin. Through further mechanism exploration, real-time PCR, immunofluorescence and Western blot analysis demonstrated that brahma related gene 1 (BRG1) was involved in the regulatory effect of MSK1 on HO-1. High expression of MSK1 could promote the resistance of AML through BRG1-mediated upregulation of HO-1. Downregulation of MSK1 enhanced the sensitivity of AML cells to Ara-C. Our findings provide novel ideas for developing effective anti-AML targets.

Quercetin reverses chronic unpredictable mild stress-induced depression-like behavior in vivo by involving nuclear factor-E2-related factor 2

Quercetin is a flavonoid compound rich in many natural plants with a wide range of pharmacological effects and nutritional value. Although previous studies have initially shown the antidepressant effect of quercetin in some models. However, the exact mechanism of the antidepressant effect of quercetin on the depression model induced by chronic unpredictable mild stress (CUMS) is still unclear or has not been clearly elucidated. The present study aimed to investigate the antidepressant effect of quercetin in vivo on a CUMS-induced depression model that is closest to human depression, and to explore its mechanism of action around nuclear factor-E2-related factor 2 (Nrf2) related signaling pathways, for the first time. Our results demonstrated that CUMS for 21 consecutive days caused significant decreases in the sucrose preference, and the horizontal score and vertical score in the open field test of mice respectively by 22.6%, 34.4%, and 66.6% (all P < 0.01), and a significant increase in the immobility time during the forced swimming test by 110.5% (P < 0.01), but fortunately, after chronic oral administration of high dose quercetin at 40 mg/kg, the abnormalities of the above indicators were significantly reversed by 26.2%, 40.1%, 152.7%, 43.5% (all P < 0.01). Further western blot analysis showed that CUMS caused the phosphorylation or expression levels of phosphoinositide 3-kinase (PI3K), protein kinase B (Akt), Nrf2 and heme oxygenase-1 (HO-1) proteins in the hippocampus of mice to significantly down-regulate by 60.0%, 72.1%, 90.0% and 50.1% (all P < 0.01), while after chronic oral administration of high dose quercetin at 40 mg/kg, the abnormalities of these proteins were significantly up-regulated by 85.8%, 182.0%, 325.1% and 60.3% (all P < 0.01). In addition, CUMS also caused significant reduction in the levels of antioxidants including superoxide dismutase (SOD) and glutathione-s transferase (GST) in the mice hippocampus by 51.3%, 40.3% (both P < 0.01), while after chronic oral administration of high dose quercetin at 40 mg/kg, the abnormalities of the above indicators were significantly reversed by 69.2% and 49.5% (both P < 0.01), as well as significant elevation in the levels of lipid peroxide malondialdehyde (MDA), inflammation medium nitric oxide (NO) and inducible nitric oxide synthase (iNOS) by 156.4%, 255.4% and 72.7% (all P < 0.01), while after chronic oral administration of high dose quercetin at 40 mg/kg, the abnormalities of the above indicators were significantly reversed by 45.9%, 26.8% and 55.2% (all P < 0.01). The medium dose of quercetin (20 mg/kg) only reversed some of the above indicators, while the low dose of quercetin (10 mg/kg) had no reversal effect on the above indicators. Collectively, the present study confirmed for the first time that quercetin weakened CUMS-induced depression in vivo, and its mechanism was at least partially attributable to the upregulation of hippocampal Nrf2 and the inhibition of iNOS, thereby correcting the central inflammatory response, and the imbalance between oxidation and antioxidant.

Gastric Helicobacter suis Infection Partially Protects against Neurotoxicity in A 6-OHDA Parkinson's Disease Mouse Model

The exact etiology of Parkinson’s disease (PD) remains largely unknown, but more and more research suggests the involvement of the gut microbiota. Interestingly, idiopathic PD patients were shown to have at least a 10 times higher prevalence of Helicobacter suis (H. suis) DNA in gastric biopsies compared to control patients. H. suis is a zoonotic Helicobacter species that naturally colonizes the stomach of pigs and non-human primates but can be transmitted to humans. Here, we investigated the influence of a gastric H. suis infection on PD disease progression through a 6-hydroxydopamine (6-OHDA) mouse model. Therefore, mice with either a short- or long-term H. suis infection were stereotactically injected with 6-OHDA in the left striatum and sampled one week later. Remarkably, a reduced loss of dopaminergic neurons was seen in the H. suis/6-OHDA groups compared to the control/6-OHDA groups. Correspondingly, motor function of the H. suis-infected 6-OHDA mice was superior to that in the non-infected 6-OHDA mice. Interestingly, we also observed higher expression levels of antioxidant genes in brain tissue from H. suis-infected 6-OHDA mice, as a potential explanation for the reduced 6-OHDA-induced cell loss. Our data support an unexpected neuroprotective effect of gastric H. suis on PD pathology, mediated through changes in oxidative stress.

Transcriptome profiling implicated in beneficiary actions of kimchi extracts against Helicobacter pylori infection

Dietary intervention to prevent Helicobacter pylori (H. pylori)-gastric cancer might be ideal because of no risk of bacterial resistance, safety, and rejuvenating action of atrophic gastritis. We have published data about the potential of fermented kimchi as nutritional approach for H. pylori. Hence recent advances in RNAseq analysis lead us to investigate the transcriptome analysis to explain these beneficiary actions of kimchi. gastric cells were infected with either H. pylori or H. pylori plus kimchi. 943 genes were identified as significantly increased or decreased genes according to H. pylori infection and 68 genes as significantly changed between H. pylori infection and H. pylori plus kimchi (p<0.05). Gene classification and Medline database showed DLL4, FGF18, PTPRN, SLC7A11, CHAC1, FGF21, ASAN, CTH, and CREBRF were identified as significantly increased after H. pylori, but significantly decreased with kimchi and NEO1, CLDN8, KLRG1, and IGFBP1 were identified as significantly decreased after H. pylori, but increased with kimchi. After KEGG and STRING-GO analysis, oxidative stress, ER stress, cell adhesion, and apoptosis genes were up-regulated with H. pylori infection but down-regulated with kimchi, whereas tissue regeneration, cellular anti-oxidative response, and anti-inflammation genes were reversely regulated with kimchi (p<0.01). Conclusively, transcriptomes of H. pylori plus kimchi showed significant biological actions.

Facing Cell Autophagy in Gastric Cancer - What Do We Know so Far?

Autophagy is a process by which misfolded proteins and damaged organelles in the lysosomes of tumor cells were degraded reusing decomposed substances and avoiding accumulation of large amounts of harmful substances. Here, the role of autophagy in the development of malignant transformation of gastric tumors, and the underlying mechanisms involved in autophagy formation, and the application of targeted autophagy in the treatment of gastric cancer were summarized.

The role of Nrf2 in autoimmunity and infectious disease: Therapeutic possibilities

Nrf2 is a cytoprotective transcription factor which is involved in ameliorating oxidative stress and toxic insults. Recently, an immunomodulatory role for Nrf2 has gained appreciation as it has been shown to protect cells and hosts alike in a variety of immune and inflammatory disorders. However, Nrf2 utilizes numerous distinct pathways to elicit its immunomodulatory effects. In this review, we summarize the literature discussing the roles of Nrf2 in autoimmunity and infectious diseases with a goal of understanding the potential to therapeutically target Nrf2.

Puerarin induces Nrf2 as a cytoprotective mechanism to prevent cadmium-induced autophagy inhibition and NLRP3 inflammasome activation in AML12 hepatic cells

Liver is the main target organ of cadmium (Cd) toxicity and puerarin (PU) has been shown to prevent Cd-induced hepatic cell damage via its antioxidant activity. Nrf2 acts as a critical regulator of cellular defense against various oxidative insults, but its role in the protection of PU against Cd-induced hepatic damage has not yet been clarified. Hereby, this study was designed to investigate the underlying mechanism using mouse hepatocyte line AML-12. Data firstly showed that Cd-inhibited Nrf2 pathway was markedly restored by PU treatment, assessed by Nrf2 nuclear translocation, protein levels of Keap1 and Nrf2 downstream target genes. Accordingly, Cd-reduced protein levels of antioxidant enzymes were significantly up-regulated by PU. Next, Nrf2 silencing cellular model was established to further elucidate the role of Nrf2 in the protection of PU against Cd-induced hepatic damage. Attenuation of Cd-induced autophagy inhibition and autophagosome accumulation by PU was remarkably countered by Nrf2 silencing. Moreover, alleviation of Cd-induced NLRP3 inflammasome activation by PU was distinctly prevented by Nrf2 knockdown, assessed by protein levels of NLRP3 inflammosome complex and downstream IL-18 and IL-1β production. Collectively, our data suggest that PU restores Cd-induced Nrf2 inhibition to prevent autophagy inhibition and NLRP3 inflammasome activation, providing novel insights into the protection of PU against Cd-induced hepatic cell damage.

Dietary intake of walnut prevented Helicobacter pylori-associated gastric cancer through rejuvenation of chronic atrophic gastritis

The fact that Fat-1 transgenic mice producing n-3 polyunsaturated fatty acids via overexpressed 3-desaturase significantly mitigated Helicobacter pylori (H. pylori)-associated gastric tumorigenesis through rejuvenation of chronic atrophic gastritis (CAG) led us to study whether dietary intake of walnut plentiful of n-3 PUFAs can be nutritional intervention to prevent H. pylori-associated gastric cancer. In our model that H. pylori-initiated, high salt diet-promoted gastric carcinogenesis, pellet diet containing 100 mg/kg and 200 mg/kg walnut was administered up to 36 weeks. As results, control mice (24 weeks) developed significant chronic CAG, in which dietary walnuts significantly ameliorated chronic atrophic gastritis. Expressions of COX-2/PGE₂/NF-κB/c-Jun, elevated in 24 weeks control group, were all significantly decreased with walnut (p<0.01). Tumor suppressive enzyme, 15-PGDH, was significantly preserved with walnut. Control mice (36 weeks) all developed significant tumors accompanied with severe CAG. However, significantly decreased tumorigenesis was noted in group treated with walnuts, in which expressions of COX-2/PGE₂/NF-κB/IL-6/STAT3, all elevated in 36 weeks control group, were significantly decreased with walnut. Defensive proteins including HO-1, Nrf2, and SOCS-1 were significantly increased in walnut group. Proliferative index as marked with Ki-67 and PCNA was significantly regulated with walnut relevant to 15-PGDH preservation. Conclusively, walnut can be an anticipating nutritional intervention against H. pylori.

Nrf2 promotes esophageal squamous cell carcinoma (ESCC) resistance to radiotherapy through the CaMKIIα-associated activation of autophagy

BACKGROUND

NF-E2-related factor 2 (Nrf2) is involved in the radiation resistance of esophageal squamous cell carcinoma (ESCC), but the underlying molecular mechanism is unclear. The purpose of our study was to explore the role of Nrf2 in the radiation resistance of ESCC and the potential molecular mechanism.

RESULTS

Nrf2 expression was introduced into Ec109 and KYSE-30 ESCC cells with lentivirus. CCK-8 and colony formation assays were used to evaluate the effect of Nrf2 on radioresistance in culture. The autophagy level was assessed by western blotting, flow cytometry, and confocal fluorescence microscopy. The effect of Nrf2 on the transcription of Ca2 +/calmodulin-dependent protein kinase II α (CaMKIIα) was studied by chromatin immunoprecipitation. We found that the overexpression of Nrf2 increased the radiation resistance of ESCC cells. Mechanistically, Nrf2 triggered the radiation resistance of ESCC cells by targeting CaMKIIα and subsequently activating autophagy. In addition, we found that Nrf2 directly regulated the transcription of CaMKIIα by binding to its promoter region. The effect of Nrf2 on radiation resistance was also explored in both a xenograft mouse model and ESCC patient samples. Consistent with the results of the in vitro study, high Nrf2 expression level resulted in in vivo radioresistance in an Ec109-derived xenograft mouse model. Furthermore, we also demonstrated that upregulations of both Nrf2 and CaMKIIα was closely related to lower survival rates of ESCC patients.

CONCLUSIONS

Our study reveals that Nrf2 promotes the radiation resistance of ESCC by targeting CaMKIIα and subsequently activating autophagy, which is characterized by the suppression of phosphorylated mTOR and p62, activation of Beclin 1, and transformation of LC3-I to LC3-II.

Interaction of 22 risk SNPs with Helicobacter pylori infection and risk of gastric cardia adenocarcinoma

Aim: To determine the prevalence of Helicobacter pylori infection and correlation between H. pylori infection and single nucleotide polymorphism (SNPs) identified in gastric cardia adenocarcinoma (GCA) patients. Methods: A case control study was performed. 22 risks of GCA-related SNPs were identified by genotyping assay and the relationship between susceptibility loci for GCA and H. pylori infection was further analyzed. Results: Helicobacter pylori infection was associated with GCA significantly (odds ratio: 1.40; 95% CI: 1.29-1.53 p < 0.01). Five GCA risk SNPs had their genotypes significantly different between H. pylori positive patients and H. pylori negative patients. Conclusion: The interaction between SNPs susceptibility loci and H. pylori infection is associated with an increased risk of GCA.

α-Lipoic Acid Inhibits IL-8 Expression by Activating Nrf2 Signaling in Helicobacter pylori-infected Gastric Epithelial Cells

Helicobacter pylori (H. pylori) causes gastritis and gastric cancers. Oxidative stress is involved in the pathological mechanism of H. pylori-induced gastritis and gastric cancer induction. Therefore, reducing oxidative stress may be beneficial for preventing the development of H. pylori-associated gastric diseases. Nuclear factor erythroid-2-related factor 2 (Nrf2) is a crucial regulator for the expression of antioxidant enzyme heme oxygenase-1 (HO-1), which protects cells from oxidative injury. α-Lipoic acid (α-LA), a naturally occurring dithiol, shows antioxidant and anti-inflammatory effects in various cells. In the present study, we examined the mechanism by which α-LA activates the Nrf2/HO-1 pathway, suppresses the production of pro-inflammatory cytokine interleukine-8 (IL-8), and reduces reactive oxygen species (ROS) in H. pylori-infected AGS cells. α-LA increased the level of phosphorylated and nuclear-translocated Nrf2 by decreasing the amount of Nrf2 sequestered in the cytoplasm by complex formation with Kelch-like ECH1-associated protein 1 (KEAP 1). By using exogenous inhibitors targeting Nrf2 and HO-1, we showed that up-regulation of activated Nrf2 and of HO-1 results in the α-LA-induced suppression of interleukin 8 (IL-8) and ROS. Consumption of α-LA-rich foods may prevent the development of H. pylori-associated gastric diseases by decreasing ROS-mediated IL-8 expression in gastric epithelial cells.