Loss of glutathione peroxidase 7 promotes TNF-α-induced NF-κB activation in Barrett's carcinogenesis

Downregulation of GPX8 in hepatocellular carcinoma: impact on tumor stemness and migration

PURPOSE

GPX8, which is found in the endoplasmic reticulum lumen, is a member of the Glutathione Peroxidases (GPXs) family. Its role in hepatocellular carcinoma (HCC) is unknown.

METHODS

Immunohistochemical staining was used to detect the protein levels of GPX8 in HCC tissue microarrays. A short hairpin RNA lentivirus was used to knock down GPX8, and the main signaling pathways were investigated using transcriptome sequencing and a phosphorylated kinase array. The sphere formation assays, cloning-formation assays and cell migration assays were used to evaluate the stemness and migration ability of HCC cells. Identifying the GPX8-interacting proteins was accomplished through immunoprecipitation and protein mass spectrometry.

RESULTS

The GPX8 protein levels were downregulated in HCC patients. Low expression of GPX8 protein was related to early recurrence and poor prognosis in HCC patients. GPX8 knockdown could enhance the stemness and migration ability of HCC cells. Consistently, Based on transcriptome analysis, multiple signaling pathways that include the PI3K-AKT and signaling pathways that regulate the pluripotency of stem cells, were activated after GPX8 knockdown. The downregulation of GPX8 could increase the expression of the tumor stemness markers KLF4, OCT4, and CD133. The in vivo downregulation of GPX8 could also promote the subcutaneous tumor-forming and migration ability of HCC cells. MK-2206, which is a small-molecule inhibitor of AKT, could reverse the tumor-promoting effects both in vivo and in vitro. We discovered that GPX8 and the 71-kDa heat shock cognate protein (Hsc70) have a direct interaction. The phosphorylation of AKT encouraged the translocation of Hsc70 into the nucleus and the expression of the PI3K p110 subunit, thereby increasing the downregulation of GPX8.

CONCLUSION

The findings from this study demonstrate the anticancer activity of GPX8 in HCC by inactivating the Hsc70/AKT pathway. The results suggest a possible therapeutic target for HCC.

Lactobacillus sp. Facilitate the Repair of DNA Damage Caused by Bile-Induced Reactive Oxygen Species in Experimental Models of Gastroesophageal Reflux Disease

Gastroesophageal reflux disease (GERD) leads to the accumulation of bile-induced reactive oxygen species and oxidative stress in esophageal tissues, causing inflammation and DNA damage. The progression sequence from healthy esophagus to GERD and eventually cancer is associated with a microbiome shift. Lactobacillus species are commensal organisms known for their probiotic and antioxidant characteristics in the healthy esophagus. This prompted us to investigate how Lactobacilli survive in a bile-rich environment during GERD, and to identify their interaction with the bile-injured esophageal cells. To model human reflux conditions, we exposed three Lactobacillus species (L. acidophilus, L. plantarum, and L. fermentum) to bile. All species were tolerant to bile possibly enabling them to colonize the esophageal epithelium under GERD conditions. Next, we assessed the antioxidant potential of Lactobacilli and role in bile injury repair: we measured bile-induced DNA damage using the ROS marker 8-oxo guanine and COMET assay. Lactobacillus addition after bile injury accelerated repair of bile-induced DNA damage through recruitment of pH2AX/RAD51 and reduced NFκB-associated inflammation in esophageal cells. This study demonstrated anti-genotoxic and anti-inflammatory effects of Lactobacilli, making them of significant interest in the prevention of Barrett's esophagus and esophageal adenocarcinoma in patients with GERD.

The Clinical Significance and Role of CXCL1 Chemokine in Gastrointestinal Cancers

One area of cancer research is the interaction between cancer cells and immune cells, in which chemokines play a vital role. Despite this, a comprehensive summary of the involvement of C-X-C motif ligand 1 (CXCL1) chemokine (also known as growth-regulated gene-α (GRO-α), melanoma growth-stimulatory activity (MGSA)) in cancer processes is lacking. To address this gap, this review provides a detailed analysis of CXCL1's role in gastrointestinal cancers, including head and neck cancer, esophageal cancer, gastric cancer, liver cancer (hepatocellular carcinoma (HCC)), cholangiocarcinoma, pancreatic cancer (pancreatic ductal adenocarcinoma), and colorectal cancer (colon cancer and rectal cancer). This paper presents the impact of CXCL1 on various molecular cancer processes, such as cancer cell proliferation, migration, and invasion, lymph node metastasis, angiogenesis, recruitment to the tumor microenvironment, and its effect on immune system cells, such as tumor-associated neutrophils (TAN), regulatory T (T_reg) cells, myeloid-derived suppressor cells (MDSCs), and macrophages. Furthermore, this review discusses the association of CXCL1 with clinical aspects of gastrointestinal cancers, including its correlation with tumor size, cancer grade, tumor-node-metastasis (TNM) stage, and patient prognosis. This paper concludes by exploring CXCL1's potential as a therapeutic target in anticancer therapy.

Activation of NOTCH signaling via DLL1 is mediated by APE1-redox-dependent NF-κB activation in oesophageal adenocarcinoma

OBJECTIVE

Oesophageal adenocarcinoma (EAC) arises in the setting of Barrett's oesophagus, an intestinal metaplastic precursor lesion that can develop in patients with chronic GERD. Here, we investigated the role of acidic bile salts, the mimicry of reflux, in activation of NOTCH signaling in EAC.

DESIGN

This study used public databases, EAC cell line models, L2-IL1β transgenic mouse model and human EAC tissue samples to identify mechanisms of NOTCH activation under reflux conditions.

RESULTS

Analysis of public databases demonstrated significant upregulation of NOTCH signaling components in EAC. In vitro studies demonstrated nuclear accumulation of active NOTCH1 cleaved fragment (NOTCH intracellular domain) and upregulation of NOTCH targets in EAC cells in response to reflux conditions. Additional investigations identified DLL1 as the predominant ligand contributing to NOTCH1 activation under reflux conditions. We discovered a novel crosstalk between APE1 redox function, reflux-induced inflammation and DLL1 upregulation where NF-κB can directly bind to and induce the expression of DLL1. The APE1 redox function was crucial for activation of the APE1-NF-κB-NOTCH axis and promoting cancer cell stem-like properties in response to reflux conditions. Overexpression of APE1 and DLL1 was detected in gastro-oesophageal junctions of the L2-IL1ß transgenic mouse model and human EAC tissue microarrays. DLL1 high levels were associated with poor overall survival in patients with EAC.

CONCLUSION

These findings underscore a unique mechanism that links redox balance, inflammation and embryonic development (NOTCH) into a common pro-tumorigenic pathway that is intrinsic to EAC cells.

APE1 redox function is required for activation of Yes-associated protein 1 under reflux conditions in Barrett's-associated esophageal adenocarcinomas

BACKGROUND

Esophageal adenocarcinoma (EAC) is characterized by poor prognosis and low survival rate. Chronic gastroesophageal reflux disease (GERD) is the main risk factor for the development of Barrett's esophagus (BE), a preneoplastic metaplastic condition, and its progression to EAC. Yes-associated protein 1 (YAP1) activation mediates stem-like properties under cellular stress. The role of acidic bile salts (ABS) in promoting YAP1 activation under reflux conditions remains unexplored.

METHODS

A combination of EAC cell lines, transgenic mice, and patient-derived xenografts were utilized in this study. mRNA expression and protein levels of APE1 and YAP1 were evaluated by qRT-PCR, western blot, and immunohistochemistry. YAP1 activation was confirmed by immunofluorescence staining and luciferase transcriptional activity reporter assay. The functional role and mechanism of regulation of YAP1 by APE1 was determined by sphere formation assay, siRNA mediated knockdown, redox-specific inhibition, and co-immunoprecipitation assays.

RESULTS

We showed that YAP1 signaling is activated in BE and EAC cells following exposure to ABS, the mimicry of reflux conditions in patients with GERD. This induction was consistent with APE1 upregulation in response to ABS. YAP1 activation was confirmed by its nuclear accumulation with corresponding up-regulation of YAP1 target genes. APE1 silencing inhibited YAP1 protein induction and reduced its nuclear expression and transcriptional activity, following ABS treatment. Further investigation revealed that APE1-redox-specific inhibition (E3330) or APE1 redox-deficient mutant (C65A) abrogated ABS-mediated YAP1 activation, indicating an APE1 redox-dependent mechanism. APE1 silencing or E3330 treatment reduced YAP1 protein levels and diminished the number and size of EAC spheroids. Mechanistically, we demonstrated that APE1 regulated YAP1 stability through interaction with β-TrCP ubiquitinase, whereas APE1-redox-specific inhibition induced YAP1 poly-ubiquitination promoting its degradation.

CONCLUSION

Our findings established a novel function of APE1 in EAC progression elucidating druggable molecular vulnerabilities via targeting APE1 or YAP1 for the treatment of EAC.

The overexpression of GPX8 is correlated with poor prognosis in GBM patients

Glutathione peroxidase 8 (GPX8), located in the endoplasmic reticulum, is associated with poor prognosis in several cancers. However, the expression and functions of GPX8 in cancers remain unclear. The purpose of this study was to explore the expression and functions of GPX8 in glioblastoma (GBM). We obtained expression data of GPX8 by accessing the TCGA, CGGA, GEPIA, and TIMER2.0 databases and validated them using western blot and immunohistochemistry. The Kaplan–Meier overall survival curve and Cox regression model were used to evaluate the prognostic value of GPX8 in glioma patients. Gene ontology (GO) and function enrichment analysis were used to investigate the potential function of GPX8 in GBM. Correlation analysis was used to clarify the role of GPX8 in proneural–mesenchymal transition (PMT). We studied the correlation between GPX8 expression and GBM immune infiltration by accessing cBioPortal and TIMER2.0 databases. Here, we demonstrated that GPX8 was significantly upregulated in GBM, and was associated with IDH-wildtype and mesenchymal subtype with poor prognosis. Survival analysis results indicated that GPX8 is an independent prognostic factor for overall survival (OS) in all WHO-grade glioma patients. Through the functional studies, we found that high expression of GPX8 correlated with mesenchymal signature and negatively correlated with proneural signature, indicating that GPX8 might promote PMT in GBM. Finally, based on correlation analysis, we found that the expression of GPX8 was associated with immune infiltration and the IL1/MYD88/IRAK/NF-κB pathway in GBM. Our results show that GPX8 is a key factor affecting the prognosis of GBM patients, and its targeting has the potential to provide a novel therapeutic approach.

Comprehensive analysis of epigenetics regulation, prognostic and the correlation with immune infiltrates of GPX7 in adult gliomas

Gliomas are the most commonly occurring malignant brain tumor characterized by an immunosuppressive microenvironment accompanied by profound epigenetic changes, thus influencing the prognosis. Glutathione peroxidase 7 (GPX7) is essential for regulating reactive oxygen species homeostasis under oxidative stress. However, little is known about the function of GPX7 in gliomas. In this study, we hypothesized that GPX7 methylation status could influence biological functions and local immune responses that ultimately impact prognosis in adult gliomas. We conducted an integrated bioinformatics analysis mining GPX7 DNA methylation status, transcriptional and survival data of glioma patients. We discovered that GPX7 was remarkably increased in glioma tissues and cell lines, and was associated with poor prognosis. This upregulation was significantly linked to clinicopathological and molecular features, besides being expressed in a cell cycle-dependent manner. Our results consistently demonstrated that upregulation of GPX7 is tightly modulated by epigenetic processes, which also impacted the overall survival of patients with low-grade gliomas (LGG). Based on the analysis of biological functions, we found that GPX7 might be involved in immune mechanisms involving both innate and adaptive immunity, type I interferon production and regulation of synaptic transmission in LGG, whereas in GBM, it is mainly related to metabolic regulation of mitochondrial dynamics. We also found that GPX7 strongly correlates with immune cell infiltration and diverse immune cell markers, suggesting its role in tumor-specific immune response and in regulating the migration of immune cell types to the tumor microenvironment. Combining these multiple data, we provided the first evidence regarding the epigenetic-mediated regulatory mechanisms underlying GPX7 activation in gliomas. Furthermore, our study brings key insights into the significant effect of GPX7 in modulating both immune molecules and in immune cell infiltration in the microenvironment of gliomas, which might impact the patient outcome, opening up future opportunities to regulate the local immune response.

GPX7 Is Targeted by miR-29b and GPX7 Knockdown Enhances Ferroptosis Induced by Erastin in Glioma

Background

Glioma is a lethal primary tumor of central nervous system. Ferroptosis is a newly identified form of necrotic cell death. Triggering ferroptosis has shown potential to eliminate aggressive tumors. GPX7, a member of glutathione peroxidase family (GPXs), has been described to participate in oxidative stress and tumorigenesis. However, the biological functions of GPX7 in glioma are still unknown.

Methods

Bioinformatics method was used to assess the prognostic role of GPX7 in glioma. CCK8, wound healing, transwell and cell apoptosis assays were performed to explore the functions of GPX7 in glioma cells. In vivo experiment was also conducted to confirm in vitro findings. Ferroptosis-related assays were carried out to investigate the association between GPX7 and ferroptosis in glioma.

Results

GPX7 was aberrantly expressed in glioma and higher expression of GPX7 was correlated with adverse outcomes. GPX7 silencing enhanced ferroptosis-related oxidative stress in glioma cells and the loss of GXP7 sensitized glioma to ferroptosis induced by erastin. Furthermore, we found that miR-29b directly suppressed GPX7 expression post-transcriptionally. Reconstitution of miR-29b enhanced erastin sensitivity, partly via GPX7 suppression.

Conclusions

Our study clarified the prognostic role of GPX7 in glioma and preliminarily revealed the role of GPX7 in ferroptosis, which may be conducive to the exploration of therapeutic targets of glioma.

The Immune Underpinnings of Barrett's-Associated Adenocarcinogenesis: a Retrial of Nefarious Immunologic Co-Conspirators

There is no doubt that chronic gastroesophageal reflux disease increases the risk of esophageal adenocarcinoma (EAC) by several fold (odds ratio, 6.4; 95% CI, 4.6-9.1), and some relationships between reflux disease-mediated inflammation and oncogenic processes have been explored; however, the precise interconnections between the immune response and genomic instabilities underlying these pathologic processes only now are emerging. Furthermore, the precise cell of origin of the precancerous stages associated with EAC development, Barrett's esophagus, be it cardia resident or embryonic remnant, may shape our interpretation of the likely immune drivers. This review integrates the current collective knowledge of the immunology underlying EAC development and outlines a framework connecting proinflammatory pathways, such as those mediated by interleukin 1β, tumor necrosis factor α, leukemia inhibitory factor, interleukin 6, signal transduction and activator of transcription 3, nuclear factor-κB, cyclooxygenase-2, and transforming growth factor β, with oncogenic pathways in the gastroesophageal reflux disease-Barrett's esophagus-EAC cancer sequence. Further defining these immune and molecular railroads may show a map of the routes taken by gastroesophageal cells on their journey toward EAC tumor phylogeny. The selective pressures applied by this immune-induced journey likely impact the phenotype and genotype of the resulting oncogenic destination and further exploration of lesser-defined immune drivers may be useful in future individualized therapies or enhanced selective application of recent immune-driven therapeutics.

Cytokine Interaction With Cancer-Associated Fibroblasts in Esophageal Cancer

Esophageal cancer (EC) is a highly aggressive cancer with poor outcomes under current treatment regimens. More recent findings suggest stroma elements, specifically cancer-associated fibroblasts (CAFs), play a role in disease occurrence and progression. Cancer-associated fibroblasts are largely the product of converted fibroblasts, but a variety of other local cell types including epithelial cells, endothelial cells, and mesenchymal cells have also been shown to transform to CAFs under the correct conditions. Cancer-associated fibroblasts primarily function in the communication between the tumor microenvironment and cancer cells via cytokine and chemokine secretions that accentuate immunosuppression and cancer growth. Cancer-associated fibroblasts also pose issues for EC treatment by contributing to resistance of current chemotherapeutics like cisplatin. Targeting this cell type directly proves difficult given the heterogeneity between CAFs subpopulations, but emerging research provides hope that treatment is on the horizon. This review aims to unravel some of the complexities surrounding CAFs’ impact on EC growth and therapy.

MicroRNAs mediated regulation of glutathione peroxidase 7 expression and its changes during adipogenesis

Glutathione peroxidase 7 (GPx7) acts as an intracellular stress sensor/transmitter and plays an important role in adipocyte differentiation and the prevention of obesity related pathologies. For this reason, finding the regulatory mechanisms that control GPx7 expression is of great importance. As microRNAs (miRNAs) could participate in the regulation of GPx7 expression, we studied the inhibition of GPx7 expression by four selected miRNAs with relation to obesity and adipogenesis. The effect of the transfection of selected miRNAs mimics on GPx7 expression was tested in three cell models (HEK293, SW480, AT-MSC). The interaction of selected miRNAs with the 3'UTR of GPx7 was followed up on using a luciferase gene reporter assay. In addition, the levels of GPx7 and selected miRNAs in adipose tissue mesenchymal stem cells (AT-MSC) and mature adipocytes from four human donors were compared, with the changes in these levels during adipogenesis analyzed. Our results show for the first time that miR-137 and miR-29b bind to the 3'UTR region of GPx7 and inhibit the expression of this enzyme at the mRNA and protein level in all the human cells tested. However, no negative correlation between miR-137 nor miR-29b level and GPx7 was observed during adipogenesis. Despite the confirmed inhibition of GPx7 expression by miR-137 and miR-29b, the action of these two molecules in adipogenesis and mature adipocytes must be accompanied by other regulators.

The antioxidant response in Barrett's tumorigenesis: A double-edged sword

Esophageal adenocarcinoma (EAC) is the dominant form of esophageal malignancies in the United States and other industrialized countries. The incidence of EAC has been rising rapidly during the past four decades. Barrett's esophagus (BE) is the main precancerous condition for EAC, where a metaplastic columnar epithelium replaces normal squamous mucosa of the lower esophagus. The primary risk factor for BE and EAC are chronic gastroesophageal reflux disease (GERD), obesity and smoking. During the BE-dysplasia-EAC sequence, esophageal cells are under a tremendous burden of accumulating reactive oxygen species (ROS) and oxidative stress. While normal cells have intact antioxidant machinery to maintain a balanced anti-tumorigenic physiological response, the antioxidant capacity is compromised in neoplastic cells with a pro-tumorigenic development antioxidant response. The accumulation of ROS, during the neoplastic progression of the GERD-BE-EAC sequence, induces DNA damage, lipid peroxidation and protein oxidation. Neoplastic cells adapt to oxidative stress by developing a pro-tumorigenic antioxidant response that keeps oxidative damage below lethal levels while promoting tumorigenesis, progression, and resistance to therapy. In this review, we will summarize the recent findings on oxidative stress in tumorigenesis in the context of the GERD-BE-EAC process. We will discuss how EAC cells adapt to increased ROS. We will review APE1 and NRF2 signaling mechanisms in the context of EAC. Finally, we will discuss the potential clinical significance of applying antioxidants or NRF2 activators as chemoprevention and NRF2 inhibitors in treating EAC patients.

Prognostic Signatures of Metabolic Genes and Metabolism-Related Long Non-coding RNAs Accurately Predict Overall Survival for Osteosarcoma Patients

In this study, we identified eight survival-related metabolic genes in differentially expressed metabolic genes by univariate Cox regression analysis based on the therapeutically applicable research to generate effective treatments (n = 84) data set and genotype tissue expression data set (n = 396). We also constructed a six metabolic gene signature to predict the overall survival of osteosarcoma (OS) patients using least absolute shrinkage and selection operator (Lasso) Cox regression analysis. Our results show that the six metabolic gene signature showed good performance in predicting survival of OS patients and was also an independent prognostic factor. Stratified correlation analysis showed that the metabolic gene signature accurately predicted survival outcomes in high-risk and low-risk OS patients. The six metabolic gene signature was also verified to perform well in predicting survival of OS patients in an independent cohort (GSE21257). Then, using univariate Cox regression and Lasso Cox regression analyses, we identified an eight metabolism-related long noncoding RNA (lncRNA) signature that accurately predicts overall survival of OS patients. Gene set variation analysis showed that the apical surface and bile acid metabolism, epithelial mesenchymal transition, and P53 pathway were activated in the high-risk group based on the eight metabolism-related lncRNA signature. Furthermore, we constructed a competing endogenous RNA (ceRNA) network and conducted immunization score analysis based on the eight metabolism-related lncRNA signature. These results showed that the six metabolic gene signature and eight metabolism-related lncRNA signature have good performance in predicting the survival outcomes of OS patients.

GPx7 ameliorates non-alcoholic steatohepatitis by regulating oxidative stress

Non-alcoholic fatty liver disease (NAFLD) is one of the most common liver diseases. NAFLD can further progress to irreversible liver failure such as non-alcoholic steatohepatitis (NASH) fibrosis and cirrhosis. However, specific regulator of NASH- fibrosis has yet to be established. Here, we found that glutathione peroxidase 7 (GPx7) was markedly expressed in NASH fibrosis. Although GPx7 is an antioxidant enzyme protecting other organs, whether GPx7 plays a role in NASH fibrosis has yet to be studied. We found that knockdown of GPx7 in transforming growth factor-β (TGF-β) and free fatty acids (FFA)- treated LX-2 cells elevated the expression of pro-fibrotic and pro-inflammatory genes and collagen synthesis. Consistently, GPx7 overexpression in LX-2 cells led to the suppression of ROS production and reduced the expression of pro-fibrotic and pro-inflammatory genes. Further, NASH fibrosis induced by choline-deficient amino acid defined, high fat diet (CDAHFD) feeding was significantly accelerated by knockdown of GPx7, as evidenced by up-regulated liver fibrosis and inflammation compared with CDAHFD control mice. Collectively, these results suggest that GPx7 might be a novel therapeutic target to prevent the progression and development of NAFLD.

Emerging roles for non-selenium containing ER-resident glutathione peroxidases in cell signaling and disease

Maintenance of cellular redox control is pivotal for normal cellular functions and cell fate decisions including cell death. Among the key cellular redox systems in mammals, the glutathione peroxidase (GPX) family of proteins is the largest conferring multifaceted functions and affecting virtually all cellular processes. The endoplasmic reticulum (ER)-resident GPXs, designated as GPX7 and GPX8, are the most recently added members of this family of enzymes. Recent studies have provided exciting insights how both enzymes support critical processes of the ER including oxidative protein folding, maintenance of ER redox control by eliminating H₂O₂, and preventing palmitic acid-induced lipotoxicity. Consequently, numerous pathological conditions, such as neurodegeneration, cancer and metabolic diseases have been linked with altered GPX7 and GPX8 expression. Studies in mice have demonstrated that loss of GPX7 leads to increased differentiation of preadipocytes, increased tumorigenesis and shortened lifespan. By contrast, GPX8 deficiency in mice results in enhanced caspase-4/11 activation and increased endotoxic shock in colitis model. With the increasing recognition that both types of enzymes are dysregulated in various tumor entities in man, we deem a review of the emerging roles played by GPX7 and GPX8 in health and disease development timely and appropriate.

GPX8 promotes migration and invasion by regulating epithelial characteristics in non-small cell lung cancer

Background

Non‐small cell lung cancer (NSCLC) is the most common cause of cancer‐related death worldwide. The family of glutathione peroxidase (GPX), an important antioxidant enzyme in human tissues, has been discovered to play a key role in the development of cancers. GPX8 is the most promising molecule of the family in a therapeutic strategy against a variety of cancers.

The main purpose of this study was to examine and analyze the function and clinical value of GPX8 in NSCLC.

Methods

Immunohistochemistry (IHC), western blot analysis and quantitative real‐time polymerase chain reaction (qPCR) were used to assess GPX8 expression and its clinical significance in NSCLC. A series of cell biology experiments and bioinformatic analysis tools were further used to study the function of GPX8.

Results

GPX8 expression in tumor tissues was much higher than that in normal lung tissues. High expression of GPX8 in NSCLC was correlated with a worse clinical outcome and prognosis. Furthermore, GPX8 could inhibit the apoptosis of tumor cells and promote its migration and invasion.

Conclusions

Our results conclusively demonstrated that GPX8 could affect the oncogenesis and prognosis of NSCLC via regulating epithelial characteristics. The study also illustrated that GPX8 could serve as a prognostic predictor and potential therapeutic target for NSCLC.

Omeprazole prevents CDX2 and SOX9 expression by inhibiting hedgehog signaling in Barrett's esophagus cells

Activation of hedgehog (Hh) signaling contributes to the progression of Barrett's esophagus (BE), which increases the risk of esophageal adenocarcinoma. Recent clinical studies revealed that proton-pump inhibitors (PPIs) but not H2 receptor antagonists (H2RAs) were associated with a decreased risk of esophageal adenocarcinoma. We would like to know whether PPIs interfere with BE progression during BE treatment. Here, we explored the role of omeprazole on Hh signaling and expression of two crucial biomarkers of BE, SOX9 and CDX2. We demonstrated that bile acids elevated expression of Hh pathway target genes, such as GLI1 and PTCH1, and induced SOX9 and CDX2 up-regulation in both CP-A and CP-B cells. Omeprazole, but not famotidine, down-regulated these genes induced by bile acids. In addition, omeprazole-induced down-regulation of SOX9 and CDX2 was mediated by Hh signaling. To explore the mechanisms by which omeprazole inhibits Hh signaling, we performed luciferase assay but did not find any effects of omeprazole on the activity of GLI1 promoter, the critical transcription factor of Hh signaling. Therefore, we used miRNA sequencing and a bioinformatics tool in our study to identify the differently expressed miRNAs in BE organoids treated with or without omeprazole, and we identified miR-2116-3p was involved in omeprazole-mediated inhibition of Hh signaling and subsequent down-regulation of SOX9 and CDX2. Collectively, our data indicate omeprazole inhibits Hh signaling and subsequent SOX9 and CDX2 expression via up-regulating miR-2116-3p. We have demonstrated a novel acid-independent mechanism of omeprazole that might yield valuable insight into clinical management of BE progression, irrespective of acid reflux symptoms.

Predictive Biomarkers of Gastroesophageal Reflux Disease and Barrett's Esophagus in World Trade Center Exposed Firefighters: a 15 Year Longitudinal Study

Gastroesophageal reflux disease (GERD) and Barrett’s Esophagus (BE), which are prevalent in the World Trade Center (WTC) exposed and general populations, negatively impact quality of life and cost of healthcare. GERD, a risk factor of BE, is linked to obstructive airways disease (OAD). We aim to identify serum biomarkers of GERD/BE, and assess the respiratory and clinical phenotype of a longitudinal cohort of never-smoking, male, WTC-exposed rescue workers presenting with pulmonary symptoms. Biomarkers collected soon after WTC-exposure were evaluated in optimized predictive models of GERD/BE. In the WTC-exposed cohort, the prevalence of BE is at least 6 times higher than in the general population. GERD/BE cases had similar lung function, D_LCO, bronchodilator response and long-acting β-agonist use compared to controls. In confounder-adjusted regression models, TNF-α ≥ 6 pg/mL predicted both GERD and BE. GERD was also predicted by C-peptide ≥ 360 pg/mL, while BE was predicted by fractalkine ≥ 250 pg/mL and IP-10 ≥ 290 pg/mL. Finally, participants with GERD had significantly increased use of short-acting β-agonist compared to controls. Overall, biomarkers sampled prior to GERD/BE presentation showed strong predictive abilities of disease development. This study frames future investigations to further our understanding of aerodigestive pathology due to particulate matter exposure.

Reprogramming human A375 amelanotic melanoma cells by catalase overexpression: Upregulation of antioxidant genes correlates with regression of melanoma malignancy and with malignant progression when downregulated

Reactive oxygen species (ROS) are implicated in tumor transformation. The antioxidant system (AOS) protects cells from ROS damage. However, it is also hijacked by cancers cells to proliferate within the tumor. Thus, identifying proteins altered by redox imbalance in cancer cells is an attractive prognostic and therapeutic tool. Gene expression microarrays in A375 melanoma cells with different ROS levels after overexpressing catalase were performed. Dissimilar phenotypes by differential compensation to hydrogen peroxide scavenging were generated. The melanotic A375-A7 (A7) upregulated TYRP1, CNTN1 and UCHL1 promoting melanogenesis. The metastatic A375-G10 (G10) downregulated MTSS1 and TIAM1, proteins absent in metastasis. Moreover, differential coexpression of AOS genes (EPHX2, GSTM3, MGST1, MSRA, TXNRD3, MGST3 and GSR) was found in A7 and G10. Their increase in A7 improved its AOS ability and therefore, oxidative stress response, resembling less aggressive tumor cells. Meanwhile, their decrease in G10 revealed a disruption in the AOS and therefore, enhanced its metastatic capacity.

These gene signatures, not only bring new insights into the physiopathology of melanoma, but also could be relevant in clinical prognostic to classify between non aggressive and metastatic melanomas.

Omeprazole Inhibits Cell Proliferation and Induces G0/G1 Cell Cycle Arrest through Up-regulating miR-203a-3p Expression in Barrett's Esophagus Cells

Existing data suggest that proton pump inhibitors (PPIs), particularly omeprazole, have significant anti-tumor action in monotherapy and or combination chemotherapy. Hedgehog (Hh) signaling pathway represents a leading candidate as a molecular mediator of Barrett's esophagus (BE). Studies have indicated reduced miRNAs in BE progression, however, little is known about the latent anti-neoplasm effects of miRNAs in BE cells. Here, we investigated whether omeprazole could inhibit BE progression by regulating Hh pathway and explored the promising Hh-targeted miRNAs in BE cells. We conducted qRT-PCR and immunoblotting assay to evaluate the effects of omeprazole on the expression of Hh signaling components and miR-203a-3p in CP-A and CP-B cells. The promising target genes of miR-203a-3p were predicted by bioinformatics methods, and verified by luciferase assays and qRT-PCR. The effects of omeprazole on BE cell proliferation and cell cycle distribution were determined. The overexpression or silencing of miR-203a-3p was performed to test its anti-proliferative effects. Finally, rescue experiments that miR-203a-3p inhibitor alleviated the effects of omeprazole on decreasing the levels of Gli1 mRNA, protein and luciferase were performed. Mechanistic studies showed that omeprazole could inhibit the expression of Gli1 and the nuclear localization of Gli1. Moreover, we determined that omeprazole could selectively up-regulated the expression of miR-203a-3p, and Gli1 was a bona fide target of miR-203a-3p. miR-203a-3p inhibitor alleviated the suppressing effects of omeprazole on Gli1 luciferase activity, mRNA and protein level. The functional assay suggested that omeprazole could dose-dependently inhibit BE cell growth and induce cell cycle arrest in G0/G1 phase. Additionally, overexpression and silencing of miR-203a-3p in BE cells disrupted cell cycle progress, resulting in suppressing and accelerating cell proliferation, respectively. Taken together, these data provide a novel mechanism of potentially anti-neoplastic effects for omeprazole through modulation of miR-203a-3p expression and thus suppressing Hh/Gli1 signaling in BE cells.

Chemopreventive Strategies for Inflammation-Related Carcinogenesis: Current Status and Future Direction

A sustained and chronically-inflamed environment is characterized by the presence of heterogeneous inflammatory cellular components, including neutrophils, macrophages, lymphocytes and fibroblasts. These infiltrated cells produce growth stimulating mediators (inflammatory cytokines and growth factors), chemotactic factors (chemokines) and genotoxic substances (reactive oxygen species and nitrogen oxide) and induce DNA damage and methylation. Therefore, chronic inflammation serves as an intrinsic niche for carcinogenesis and tumor progression. In this article, we summarize the up-to-date findings regarding definitive/possible causes and mechanisms of inflammation-related carcinogenesis derived from experimental and clinical studies. We also propose 10 strategies, as well as candidate agents for the prevention of inflammation-related carcinogenesis.

Redox signaling in the gastrointestinal tract

Redox signaling regulates physiological self-renewal, proliferation, migration and differentiation in gastrointestinal epithelium by modulating Wnt/β-catenin and Notch signaling pathways mainly through NADPH oxidases (NOXs). In the intestine, intracellular and extracellular thiol redox status modulates the proliferative potential of epithelial cells. Furthermore, commensal bacteria contribute to intestine epithelial homeostasis through NOX1- and dual oxidase 2-derived reactive oxygen species (ROS). The loss of redox homeostasis is involved in the pathogenesis and development of a wide diversity of gastrointestinal disorders, such as Barrett's esophagus, esophageal adenocarcinoma, peptic ulcer, gastric cancer, ischemic intestinal injury, celiac disease, inflammatory bowel disease and colorectal cancer. The overproduction of superoxide anion together with inactivation of superoxide dismutase are involved in the pathogenesis of Barrett's esophagus and its transformation to adenocarcinoma. In Helicobacter pylori-induced peptic ulcer, oxidative stress derived from the leukocyte infiltrate and NOX1 aggravates mucosal damage, especially in HspB+ strains that downregulate Nrf2. In celiac disease, oxidative stress mediates most of the cytotoxic effects induced by gluten peptides and increases transglutaminase levels, whereas nitrosative stress contributes to the impairment of tight junctions. Progression of inflammatory bowel disease relies on the balance between pro-inflammatory redox-sensitive pathways, such as NLRP3 inflammasome and NF-κB, and the adaptive up-regulation of Mn superoxide dismutase and glutathione peroxidase 2. In colorectal cancer, redox signaling exhibits two Janus faces: On the one hand, NOX1 up-regulation and derived hydrogen peroxide enhance Wnt/β-catenin and Notch proliferating pathways; on the other hand, ROS may disrupt tumor progression through different pro-apoptotic mechanisms. In conclusion, redox signaling plays a critical role in the physiology and pathophysiology of gastrointestinal tract.

Overview of major molecular alterations during progression from Barrett's esophagus to esophageal adenocarcinoma

Esophageal adenocarcinoma (EAC) develops in the sequential transformation of normal epithelium into metaplastic epithelium, called Barrett's esophagus (BE), then to dysplasia, and finally cancer. BE is a common condition in which normal stratified squamous epithelium of the esophagus is replaced with an intestine-like columnar epithelium, and it is the most prominent risk factor for EAC. This review aims to impartially systemize the knowledge from a large number of publications that describe the molecular and biochemical alterations occurring over this progression sequence. In order to provide an unbiased extraction of the knowledge from the literature, a text-mining methodology was used to select genes that are involved in the BE progression, with the top candidate genes found to be TP53, CDKN2A, CTNNB1, CDH1, GPX3, and NOX5. In addition, sample frequencies across analyzed patient cohorts at each stage of disease progression are summarized. All six genes are altered in the majority of EAC patients, and accumulation of alterations correlates well with the sequential progression of BE to cancer, indicating that the text-mining method is a valid approach for gene prioritization. This review discusses how, besides being cancer drivers, these genes are functionally interconnected and might collectively be considered a central hub of BE progression.

NPGPx (GPx7): a novel oxidative stress sensor/transmitter with multiple roles in redox homeostasis

NPGPx (GPx7) is a member of the glutathione peroxidase (GPx) family without any GPx activity. GPx7 displays a unique function which serves as a stress sensor/transmitter to transfer the signal to its interacting proteins by shuttling disulfide bonds in response to various stresses. In this review, we focus on the exceptional structural and biochemical features of GPx7 compared to other 7 family members and described how GPx7 regulates the diverse signaling targets including GRP78, PDI, CPEB2, and XRN2, and their different roles in unfolded protein response, oxidative stress, and non-targeting siRNA stress response, respectively. The phenotypes associated with GPx7 deficiency in mouse or human including ROS accumulations, highly elevated cancer incidences, auto-immune disorders, and obesity are also revealed in this paper. Finally, we compare GPx8 with GPx7, which shares the highest structural similarity but different biological roles in stress response. These insights have thus provided a more comprehensive understanding of the role of GPx7 in the maintenance of redox homeostasis.

Hint1 Up-Regulates IκBα by Targeting the β-TrCP Subunit of SCF E3 Ligase in Human Hepatocellular Carcinoma Cells

BACKGROUND AND AIM

There is increasing evidence that histidine triad nucleotide-binding protein 1 (HINT1) is a novel tumor suppressor. In the present study, we investigated the mechanism by which HINT1 promotes the stability of inhibitor of NF-κB α (IκBα) in the cytoplasm of hepatocellular carcinoma (HCC) cells, which was observed in our previous study (Wang et al. in Int J Cancer 124:1526-1534, 2009).

METHODS

We examined HINT1 and IκBα expression in HCC cell lines and determined the effect of HINT1 overexpression and knockdown on IκBα protein and mRNA expression in these cell lines. Then, ubiquitination assays were performed to investigate the effects of HINT1 expression plasmid transfection on IκBα ubiquitination. Next, the interaction between HINT1 and β-TrCP was investigated in immunoprecipitation and immunofluorescence assays.

RESULTS

Our data showed that increased HINT1 expression in HepG2 and SMMC7702 cells markedly increased IκBα protein levels, while decreased HINT1 expression markedly decreased them. Overexpression or knockdown of HINT1 did not alter the transcription of IκBα, but HINT1 inhibited proteasomal IκBα degradation and reduced its ubiquitination levels. This inhibition might occur because HINT1 is a component of the SCF(β-TrCP) E3 ligase, which is responsible for IκBα ubiquitination and degradation.

CONCLUSION

This study provides new evidence that HINT1 is a regulator of IκBα through SCF(β-TrCP) E3 ligase. These findings help to clarify the mechanism underlying the anticancer effects of HINT1.

Prevention strategies for esophageal cancer: Perspectives of the East vs. West

Esophageal cancer is the eighth most common cancer worldwide. Esophageal adenocarcinoma (EAC) and esophageal squamous cell carcinoma (ESCC) are the two major phenotypes in Western and Eastern countries, respectively. Because of different pathways in carcinogenesis, the risk factors and effective steps for prevention of esophageal cancer are different between EAC and ESCC. The carcinogenesis of EAC is initiated by the acid exposure of the esophageal mucosa from stomach while that of the ESCC are related to the chronic irritation of carcinogens mainly by the alcohol, cigarette, betel quid, and hot beverage. To eliminate the burden of esophageal cancer on the global health, the effective strategy should be composed of the primary, secondary, and tertiary prevention. In this article, we perform a systematic review of the preventive strategies for esophageal cancer with special emphasis on the differences from the perspectives of Western and Eastern countries.

NPGPx modulates CPEB2-controlled HIF-1α RNA translation in response to oxidative stress

Non-selenocysteine-containing phospholipid hydroperoxide glutathione peroxidase (NPGPx or GPx7) is an oxidative stress sensor that modulates the antioxidative activity of its target proteins through intermolecular disulfide bond formation. Given NPGPx's role in protecting cells from oxidative damage, identification of the oxidative stress-induced protein complexes, which forms with key stress factors, may offer novel insight into intracellular reactive oxygen species homeostasis. Here, we show that NPGPx forms a disulfide bond with the translational regulator cytoplasmic polyadenylation element-binding protein 2 (CPEB2) that results in negative regulation of hypoxia-inducible factor 1-alpha (HIF-1α) RNA translation. In NPGPx-proficient cells, high oxidative stress that disrupts this bonding compromises the association of CPEB2 with HIF-1α RNA, leading to elevated HIF-1α RNA translation. NPGPx-deficient cells, in contrast, demonstrate increased HIF-1α RNA translation under normoxia with both impaired induction of HIF-1α synthesis and blunted HIF-1α-programmed transcription following oxidative stress. Together, these results reveal a molecular mechanism for how NPGPx mediates CPEB2-controlled HIF-1α RNA translation in a redox-sensitive manner.

The antioxidant machinery of the endoplasmic reticulum: Protection and signaling

Cellular metabolism is inherently linked to the production of oxidizing by-products, including reactive oxygen species (ROS) hydrogen peroxide (H2O2). When present in excess, H2O2 can damage cellular biomolecules, but when produced in coordinated fashion, it typically serves as a mobile signaling messenger. It is therefore not surprising that cell health critically relies on both low-molecular-weight and enzymatic antioxidant components, which protect from ROS-mediated damage and shape the propagation and duration of ROS signals. This review focuses on H2O2-antioxidant cross talk in the endoplasmic reticulum (ER), which is intimately linked to the process of oxidative protein folding. ER-resident or ER-regulated sources of H2O2 and other ROS, which are subgrouped into constitutive and stimulated sources, are discussed and set into context with the diverse antioxidant mechanisms in the organelle. These include two types of peroxide-reducing enzymes, a high concentration of glutathione derived from the cytosol, and feedback-regulated thiol-disulfide switches, which negatively control the major ER oxidase ER oxidoreductin-1. Finally, new evidence highlighting emerging principles of H2O2-based cues at the ER will likely set a basis for establishing ER redox processes as a major line of future signaling research. A fundamental problem that remains to be solved is the specific, quantitative, time resolved, and targeted detection of H2O2 in the ER and in specialized ER subdomains.

Is Campylobacter to esophageal adenocarcinoma as Helicobacter is to gastric adenocarcinoma?

Esophageal adenocarcinoma develops through a cascade of cellular changes that shares similarities to the etiology of Helicobacter pylori-associated intestinal-type gastric adenocarcinoma. While host genetics and immune response have been implicated in the progression to esophageal adenocarcinoma, studies investigating esophageal microbial communities suggest that bacteria may also play an important role in driving the inflammation that leads to disease. Of these, emerging Campylobacter species have been found to be more prevalent and abundant in patients progressing through the esophageal adenocarcinoma cascade compared to controls. Given that these bacteria possess several virulence mechanisms such as toxin production, cellular invasion, and intracellular survival, emerging Campylobacter species should be investigated as etiological agents of the chronic esophageal inflammation that leads to cancer.