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Infection with Helicobacter pylori (H. pylori) is the main risk factor for gastric cancer, a leading cause of cancer-related death worldwide. The oncogenic functions of cyclin-dependent kinase 1 (CDK1) are not fully understood in gastric tumorigenesis. Using public datasets, quantitative real-time PCR, western blot, and immunohistochemical (IHC) analyses, we detect high levels of CDK1 in human and mouse gastric tumors. H. pylori infection induces activation of nuclear factor κB (NF-κB) with a significant increase in CDK1 in in vitro and in vivo models (p < 0.01). We confirm active NF-κB binding sites on the CDK1 promoter sequence. CDK1 phosphorylates and inhibits GSK-3β activity through direct binding with subsequent accumulation and activation of β-catenin. CDK1 silencing or pharmacologic inhibition reverses these effects and impairs tumor organoids and spheroid formation. IHC analysis demonstrates a positive correlation between CDK1 and β-catenin. The results demonstrate a mechanistic link between infection, inflammation, and gastric tumorigenesis where CDK1 plays a critical role. [Display omitted] • Infection with H. pylori is the main risk factor for gastric tumorigenesis • H. pylori infection induces CDK1 expression via an NF-κB-dependent transcription • CDK1 promotes activation of β-catenin signaling and cellular expansion Zhu et al. show induction of CDK1 in response to H. pylori infection via NF-κB-dependent transcription regulation. CDK1-mediated activation of β-catenin signaling, promoting expansion of cancer cells. The results demonstrate a mechanistic link between infection, inflammation, and gastric tumorigenesis where CDK1 plays a critical role. [ABSTRACT FROM AUTHOR]

Helicobacter pylori (H pylori) infection is the main risk factor for gastric cancer. The role of fibroblast growth factor receptors (FGRFs) in H pylori -mediated gastric tumorigenesis remains largely unknown. This study investigated the molecular and mechanistic links between H pylori , inflammation, and FGFR4 in gastric cancer. Cell lines, human and mouse gastric tissue samples, and gastric organoids models were implemented. Infection with H pylori was performed using in vitro and in vivo models. Western blot, real-time quantitative reverse-transcription polymerase chain reaction, flow cytometry, immunofluorescence, immunohistochemistry, chromatin immunoprecipitation, and luciferase reporter assays were used for molecular, mechanistic, and functional studies. Analysis of FGFR family members using The Cancer Genome Atlas data, followed by validation, indicated that FGFR4 messenger (m)RNA was the most significantly overexpressed member in human gastric cancer tissue samples (P <.001). We also detected high levels of Fgfr4 mRNA and protein in gastric dysplasia and adenocarcinoma lesions in mouse models. Infection with J166, 7.13, and PMSS1 cytotoxin-associated gene A (CagA)+ H pylori strains induced FGFR4 mRNA and protein expression in in vitro and in vivo models. This was associated with a concordant activation of signal transducer and activator of transcription 3 (STAT3). Analysis of the FGFR4 promoter suggested several putative binding sites for STAT3. Using chromatin immunoprecipitation assay and an FGFR -promoter luciferase reporter containing putative STAT3 binding sites and their mutants, we confirmed a direct functional binding of STAT3 on the FGFR4 promoter. Mechanistically, we also discovered a feedforward activation loop between FGFR4 and STAT3 where the fibroblast growth factor 19–FGFR4 axis played an essential role in activating STAT3 in a steroid receptor coactivator–dependent manner. Functionally, we found that FGFR4 protected against H pylori -induced DNA damage and cell death. Our findings demonstrated a link between infection, inflammation, and FGFR4 activation, where a feedforward activation loop between FGFR4 and STAT3 is established via steroid receptor coactivator in response to H pylori infection. Given the relevance of FGFR4 to the etiology and biology of gastric cancer, we propose FGFR4 as a druggable molecular vulnerability that can be tested in patients with gastric cancer. [Display omitted] Helicobacter pylori infection is a key step driving a novel tumorigenic feedforward signaling loop linking infection, inflammation, and fibroblast growth factor receptor 4 activation in gastric cancer. [ABSTRACT FROM AUTHOR]

Helicobacter pylori infection is the predominant risk factor for gastric cancer. RAS protein activator like 2 (RASAL2) is considered a double-edged sword in carcinogenesis. Herein, we investigated the role of RASAL2 in response to H pylori infection and gastric tumorigenesis. Bioinformatics analyses of local and public databases were applied to analyze RASAL2 expression, signaling pathways, and clinical significance. In vitro cell culture, spheroids, patient-derived organoids, and in vivo mouse models were used. Molecular assays included chromatin immunoprecipitation, co-immunoprecipitation, Western blotting, quantitative polymerase chain reaction, and immunocyto/histochemistry. H pylori infection induced RASAL2 expression via a nuclear factor-κB (NF-κB)-dependent mechanism whereby NF-κB was directly bound to the RASAL2 promoter activating its transcription. By gene silencing and ectopic overexpression, we found that RASAL2 upregulated β-catenin transcriptional activity. RASAL2 inhibited protein phosphatase 2A activity through direct binding with subsequent activation of the AKT/β-catenin signaling axis. Functionally, RASAL2 silencing decreased nuclear β-catenin levels and impaired tumor spheroids and organoids formation. Furthermore, the depletion of RASAL2 impaired tumor growth in gastric tumor xenograft mouse models. Clinicopathological analysis indicated that abnormal overexpression of RASAL2 correlated with poor prognosis and chemoresistance in human gastric tumors. These studies uncovered a novel signaling axis of NF-κB/RASAL2/β-catenin, providing a novel link between infection, inflammation and gastric tumorigenesis. [Display omitted] Our study uncovers a signaling axis of nuclear factor-κB/RAS protein activator like 2/β-catenin, providing a novel link between infection, inflammation, and gastric tumorigenesis. [ABSTRACT FROM AUTHOR]

Background: Gastric adenocarcinoma is a leading cause of cancer mortality. The role of dopamine and cAMP regulated phosphoprotein MW 32 kDa (DARPP-32) overexpression in the gastric tumorigenesis cascade remains unclear. Methods: The expression of DARPP-32 in the multistep carcinogenesis cascade was examined using immunohistochemistry analysis on 533 samples. The contribution of DARPP-32 in cellular transformation and molecular signaling was investigated using NIH3T3, AGS, and SNU16 cells. Results: The composite expression score (CES), calculated from immunostaining patterns, increased significantly from normal or gastritis to metaplasia, dysplasia, and adenocarcinoma (P < .001). In patients with normal stomach or gastritis and tumor samples, a 76% and 77% chance, respectively, was found (P < .001) that CES was higher in the tumor. High median CES correlated with well- or moderately differentiated (P = .03) gastric adenocarcinomas. NIH3T3 cells transfected with DARPP-32 demonstrated increased levels of phospho-AKT and a 5-fold increase in the number of foci as compared with the control (P = .02). DARPP-32 expression in AGS cells led to increased protein levels of phospho-AKT and BCL-2. For validation, the knockdown of endogenous DARPP-32 expression in SNU16 cells using shRNA resulted in decreased levels of phospho-AKT phosphorylation and BCL-2. Conclusion: Our results suggest that DARPP-32 overexpression may participate in the transition to intestinal metaplasia and in the progression to neoplasia. The ability of DARPP-32 to transform NIH3T3 cells and to regulate AKT and BCL-2 underscores its possible oncogenic potential. [Copyright &y& Elsevier]

Background & Aims: Chronic inflammation contributes to the pathogenesis of gastric tumorigenesis. The aurora kinase A (AURKA) gene is frequently amplified and overexpressed in gastrointestinal cancers. We investigated the roles of AURKA in inflammation and gastric tumorigenesis. Methods: We used quantitative real-time reverse transcription polymerase chain reaction, immunofluorescence, immunohistochemistry, luciferase reporter, immunoblot, co-immunoprecipitation, and in vitro kinase assays to analyze AGS and MKN28 gastric cancer cells. We also analyzed Tff1−/− mice, growth of tumor xenografts, and human tissues. Results: We correlated increased expression of AURKA with increased levels of tumor necrosis factor-α and inflammation in the gastric mucosa of Tff1−/− mice (r = 0.62; P = .0001). MLN8237, an investigational small-molecule selective inhibitor of AURKA, reduced nuclear staining of nuclear factor-κB (NF-κB) p65 in human gastric cancer samples and mouse epithelial cells, suppressed NF-κB reporter activity, and reduced expression of NF-κB target genes that regulate inflammation and cell survival. Inhibition of AURKA also reduced growth of xenograft tumors from human gastric cancer cells in mice and reversed the development of gastric tumors in Tff1−/− mice. AURKA was found to regulate NF-κB activity by binding directly and phosphorylating IκBα in cells. Premalignant and malignant lesions from the gastric mucosa of patients had increased levels of AURKA protein and nuclear NF-κB, compared with healthy gastric tissue. Conclusions: In analyses of gastric cancer cell lines, human tissue samples, and mouse models, we found AURKA to be up-regulated during chronic inflammation to promote activation of NF-κB and tumorigenesis. AURKA inhibitors might be developed as therapeutic agents for gastric cancer. [Copyright &y& Elsevier]

Abstract: To determine the relevance of MGMT in Barrett’s carcinogenesis, we analyzed promotor hypermethylation and expression of MGMT in Barrett’s adenocarcinomas and its paired precursor lesions from 133 patients using a methylation-specific PCR, real-time RT-PCR and immunohistochemistry. Hypermethylation was detected in 78.9% of esophageal adenocarcinomas, in 100% of Barrett’s intraepithelial neoplasia, in 88.9% of Barrett’s metaplasia, but only in 21.4% of normal esophageal mucosa samples (P <0.001) and correlated significantly with downregulation of MGMT transcripts (P =0.048) and protein expression (P =0.02). Decrease of protein expression was significantly correlated with progressed stage of disease, lymph node invasion and tumor size. We conclude, that aberrant promoter methylation of MGMT is a frequent and early event during tumorigenesis of Barrett’s esophagus. High prevalence of MGMT hypermethylation may represent a candidate marker for improved diagnosis and targeted therapy in Barrett’s adenocarcinoma. [Copyright &y& Elsevier]

In this study, we investigated the mRNA and protein expression of S100A2 and S100A4 in adenocarcinomas of the stomach and esophagus. Real-time reverse transcription-polymerase reaction analysis on 72 tumors revealed frequent overexpression of S100A2 and S100A4 in Barrett's adenocarcinomas (BAs) (P ≤ .01). Immunohistochemical analysis on tumor tissue microarrays that contained 187 tumors showed absent to weak staining for S100A2 in all normal gastric mucosa samples, whereas normal esophageal mucosa samples demonstrated moderate to strong nuclear staining. Contrary to the nuclear expression of S100A2 in normal esophageal mucosa, two thirds of Barrett's dysplasia and BAs that overexpressed S100A2 demonstrated stronger cytosolic staining than nuclear staining (P ≤ .001). Overexpression of S100A2 protein was more frequently seen in well-differentiated tumors than in others (P = .02). Moderate to strong staining of S100A4 was detected in two thirds of tumors and was frequently observed in the presence of Barrett's esophagus (P = .02). Similar to S100A2, the expression of S100A4 was predominantly cytosolic in two thirds of the tumors (P = .001). There was a significant correlation between S100A4 overexpression and lymph node metastasis (N2-N4) (P = .027). These results demonstrate frequent cytosolic overexpression of S100A2 and S100A4 in BAs. Further studies are ongoing to understand the biological significance of these S100A proteins in Barrett's tumorigenesis. [ABSTRACT FROM AUTHOR]