Gene expression changes in patient-matched gastric normal mucosa, adenomas, and carcinomas

Exosome miR-3184-5p inhibits gastric cancer growth by targeting XBP1 to regulate the AKT, STAT3, and IRE1 signalling pathways

MicroRNAs can regulate the transcription of protein-coding genes associated with the development and progression of cancer. In this study, we explored the potential diagnostic function of exosome miR-3184-5p in gastric cancer. This exosome was isolated from the blood samples of 150 patients with gastric cancer and 60 healthy participants. The mean particle size and concentration of serum exosome in the patients with gastric cancer were 104.6 nm (93.97-115.84) and 6.21e+009 particles/ml (5.15e+009-7.12e+009), respectively. miR-3184-5p expression was substantially downregulated in the patients with gastric cancer compared with that in the healthy participants. The gastric cancer cell line HGC-27 was cultured and transfected with the mimic and an inhibitor to overexpress and inhibit miR-3184-5p expression. miR-3184-5p strongly suppressed cell proliferation, migration, and invasion but induced cell apoptosis. Luciferase reporter assay revealed that XBP1 was the target of miR-3184-5p. miR-3184-5p substantially downregulated the expression of CD44, cyclin D1, MMP2, p65, p-AKT, and p-STAT3 but upregulated that of GRP78, IRE1, p-JNK, and CHOP. Moreover, miR-3184-5p cleaved caspase-12 and inhibited BCL-2 expression. These results suggested that the downregulation of miR-3184-5p in patients with gastric cancer might regulate the AKT, STAT3, and IRE1 pathways to promote the vitality of gastric cancer cells.

Clinically applicable 53-Gene prognostic assay predicts chemotherapy benefit in gastric cancer: A multicenter study

BACKGROUND

We previously established a 53-gene prognostic signature for overall survival (OS) of gastric cancer patients. This retrospective multi-center study aimed to develop a clinically applicable gene expression detection assay and to investigate the prognostic value of this signature.

METHODS

A TCGA gastric adenocarcinoma cohort (TCGA-STAD) was used for comparing 53-gene signature with other gene signatures. A high-throughput mRNA hybridization gene expression assay was developed to quantify the expression of 53-genes in formalin-fixed paraffin-embedded tissues of 540 patients enrolled from three hospitals. 180 patents were randomly selected from two hospitals to build a prognostic prediction model based on the 53-gene signature using leave-p-out (one-third out) cross-validation method together with Cox regression and Kaplan-Meier analysis, and the model was assessed on three validation cohorts.

FINDINGS

In the evaluation phase, studies based on TCGA-STAD showed that the 53-gene signature was significantly superior to other three prognostic signatures and was independent of TCGA molecular subtypes and clinical factors. For clinical validation and utility, the prognostic scores were generated using the newly developed assay, which was reliable and sensitive, in 100 sampling training sets and were significantly associated with OS in 100 sampling validation sets. The scores were significantly associated with OS in three independent and combined validation cohorts, and in patients with stages II and III/IV. The multivariate Cox regression demonstrated that the prognostic power of the score was independent of clinical factors, consistent with those findings in the TCGA dataset. Finally, patients with good prognostic scores exhibited significantly a better 5-year OS rate from adjuvant FOLFOX chemotherapy after surgery than from other chemotherapies.

INTERPRETATION

The 53-gene prognostic score system is clinically applicable for predicting the OS of patients independent of clinical factors in gastric cancers, which could also be a promising predictive biomarker for FOLFOX regimen.

FUNDING

Chinese National Science and Technology, National Natural Science Foundation and Natural Science Foundation of Jiangsu Province.

Differential networking meta-analysis of gastric cancer across Asian and American racial groups

Background

Gastric Carcinoma is one of the most lethal cancer around the world, and is also the most common cancers in Eastern Asia. A lot of differentially expressed genes have been detected as being associated with Gastric Carcinoma (GC) progression, however, little is known about the underlying dysfunctional regulation mechanisms. To address this problem, we previously developed a differential networking approach that is characterized by involving differential coexpression analysis (DCEA), stage-specific gene regulatory network (GRN) modelling and differential regulation networking (DRN) analysis.

Result

In order to implement differential networking meta-analysis, we developed a novel framework which integrated the following steps. Considering the complexity and diversity of gastric carcinogenesis, we first collected three datasets (GSE54129, GSE24375 and TCGA-STAD) for Chinese, Korean and American, and aimed to investigate the common dysregulation mechanisms of gastric carcinogenesis across racial groups. Then, we constructed conditional GRNs for gastric cancer corresponding to normal and carcinoma, and prioritized differentially regulated genes (DRGs) and gene links (DRLs) from three datasets separately by using our previously developed differential networking method. Based on our integrated differential regulation information from three datasets and prior knowledge (e.g., transcription factor (TF)-target regulatory relationships and known signaling pathways), we eventually generated testable hypotheses on the regulation mechanisms of two genes, XBP1 and GIF, out of 16 common cross-racial DRGs in gastric carcinogenesis.

Conclusion

The current cross-racial integrative study from the viewpoint of differential regulation networking provided useful clues for understanding the common dysfunctional regulation mechanisms of gastric cancer progression and discovering new universal drug targets or biomarkers for gastric cancer.

Electronic supplementary material

The online version of this article (10.1186/s12918-018-0564-z) contains supplementary material, which is available to authorized users.

Gastric Cancer Associated Genes Identified by an Integrative Analysis of Gene Expression Data

Gastric cancer is one of the most severe complex diseases with high morbidity and mortality in the world. The molecular mechanisms and risk factors for this disease are still not clear since the cancer heterogeneity caused by different genetic and environmental factors. With more and more expression data accumulated nowadays, we can perform integrative analysis for these data to understand the complexity of gastric cancer and to identify consensus players for the heterogeneous cancer. In the present work, we screened the published gene expression data and analyzed them with integrative tool, combined with pathway and gene ontology enrichment investigation. We identified several consensus differentially expressed genes and these genes were further confirmed with literature mining; at last, two genes, that is, immunoglobulin J chain and C-X-C motif chemokine ligand 17, were screened as novel gastric cancer associated genes. Experimental validation is proposed to further confirm this finding.

Clinical and Therapeutic Implications of Follistatin in Solid Tumours

Follistatin (FST), as a single-chain glycosylated protein, has two major isoforms, FST288 and FST315. The FST315 isoform is the predominant form whilst the FST288 variant accounts for less than 5% of the encoded mRNA. FST is differentially expressed in human tissues and aberrant expression has been observed in a variety of solid tumours, including gonadal, gastric and lung cancer, hepatocellular carcinoma, basal cell carcinoma and melanoma. Based on the current evidence, FST is an antagonist of transforming growth factor beta family members, such as activin and bone morphogenetic proteins (BMPs). FST plays a role in tumourigenesis, metastasis and angiogenesis of solid tumours through its interaction with activin and BMPs, thus resulting in pathophysiological function. In terms of diagnosis, prognosis and therapy, FST has shown strong promise. Through a better understanding of its biological functions, potential clinical applications may yet emerge.

Chromoendoscopy in combination with random biopsies does not improve detection of gastric cancer foci in CDH1 mutation positive patients

Background and study aims: Hereditary diffuse gastric cancer (HGGC), an autosomal dominant tumor-syndrome, accounts for 1 % to 3 % of gastric cancers worldwide. Presumably 30 % to 40 % of all patients fulfilling the clinical guidelines for HDGC are carriers of a pathogenic mutation in the CDH1 gene. Patients often show multiple foci of signet ring cell carcinoma at early age and are advised to undergo prophylactic total gastrectomy (PTG). Our aim was to improve the endoscopic detection of HDGC by using an enhanced endoscopic protocol. Patient and methods: Patients with a proven CDH1 germline mutation identified in our institute were prospectively included. Patients were advised to undergo PTG and offered a baseline endoscopic examination prior surgery. Examination was performed by using high-resolution white-light endoscopy and pan-gastric chromoendoscopy with indigo carmine as dye combined with targeted and multiple random biopsies assessed by an expert histopathologist. Postoperative histopathology was compared with results from endoscopic biopsies. Results: Between September 2012 and November 2014 8 patients with a proven CDH1 germline mutation were included. We conducted 44 targeted (6.3/patient) and 225 random (32.1/patient) biopsies in 7 patients. We detected 1 gastric cancer by random biopsy (14 %). All other examinations showed no signs of cancer. Histopathology of gastrectomy specimen revealed multiple foci of gastric carcinoma in 6 patients (86 %) with a total number of 27 cancer foci. Conclusions: Examination with targeted and random biopsies combined with chromoendoscopy is not able to detect small foci of gastric cancer in CDH1 mutation carriers. Therefore PTG is advocated in these patients.

Epithelial Regeneration After Gastric Ulceration Causes Prolonged Cell-Type Alterations

BACKGROUND & AIMS

The peptic ulcer heals through a complex process, although the ulcer relapse often occurs several years later after healing. Our hypothesis is that even after visual evidence of healing of gastric ulceration, the regenerated epithelium is aberrant for an extended interval, increasing susceptibility of the regenerated epithelium to damage and further diseases.

METHODS

Gastric ulcers were induced in mice by serosal topical application of acetic acid.

RESULTS

Gastric ulcers induced by acetic acid visually healed within 30 days. However, regenerated epithelial architecture was poor. The gene profile of regenerated tissue was abnormal, indicating increased stem/progenitor cells, deficient differentiated gastric cell types, and deranged cell homeostasis. Despite up-regulation of PDX1 in the regenerated epithelium, no mature antral cell type was observed. Four months after healing, the regenerated epithelium lacks parietal cells, trefoil factor 2 (TFF2) and (sex-determining region Y)-box 9 (SOX9) remain up-regulated deep in the gastric gland, and the Na/H exchanger 2 (a TFF2 effector in gastric healing) remains down-regulated. Gastric ulcer healing was strongly delayed in TFF2 knockout mice, and re-epithelialization was accompanied with mucous metaplasia. After Helicobacter pylori inoculum 30 days after ulceration, we observed that the gastric ulcer selectively relapses at the same site where it originally was induced. Follow-up evaluation at 8 months showed that the relapsed ulcer was not healed in H pylori-infected tissues.

CONCLUSIONS

These findings show that this macroscopically regenerated epithelium has prolonged abnormal cell distribution and is differentially susceptible to subsequent damage by H pylori.

Molecular classification and prediction in gastric cancer

Gastric cancer, a highly heterogeneous disease, is the second leading cause of cancer death and the fourth most common cancer globally, with East Asia accounting for more than half of cases annually. Alongside TNM staging, gastric cancer clinic has two well-recognized classification systems, the Lauren classification that subdivides gastric adenocarcinoma into intestinal and diffuse types and the alternative World Health Organization system that divides gastric cancer into papillary, tubular, mucinous (colloid), and poorly cohesive carcinomas. Both classification systems enable a better understanding of the histogenesis and the biology of gastric cancer yet have a limited clinical utility in guiding patient therapy due to the molecular heterogeneity of gastric cancer. Unprecedented whole-genome-scale data have been catalyzing and advancing the molecular subtyping approach. Here we cataloged and compared those published gene expression profiling signatures in gastric cancer. We summarized recent integrated genomic characterization of gastric cancer based on additional data of somatic mutation, chromosomal instability, EBV virus infection, and DNA methylation. We identified the consensus patterns across these signatures and identified the underlying molecular pathways and biological functions. The identification of molecular subtyping of gastric adenocarcinoma and the development of integrated genomics approaches for clinical applications such as prediction of clinical intervening emerge as an essential phase toward personalized medicine in treating gastric cancer.

Trefoil factors: Gastrointestinal-specific proteins associated with gastric cancer

Trefoil factor family (TFF), composed of TFF1, TFF2, and TFF3, is a cluster of secreted peptides characterized by trefoil domain (s) and C-terminal dimerization domain. TFF1, a gastric tumor suppressor, is a single trefoil peptide originally detected in breast cancer cell lines but expressed mainly in the stomach; TFF2, a candidate of gastric cancer suppressor with two trefoil domains, is abundant in the stomach and duodenal Brunner's glands; and TFF3 is another single trefoil peptide expressed throughout the intestine which can promote the development of gastric carcinoma. According to multiple studies, TFFs play a regulatory function in the mammals' digestive system, namely in mucosal protection and epithelial cell reconstruction, tumor suppression or promotion, signal transduction and the regulation of proliferation and apoptosis. Action mechanisms of TFFs remain unresolved, but the recent demonstration of a GKN (gastrokine) 2-TFF1 heterodimer implicates structural and functional interplay with gastrokines. This review aims to encapsulate the structural and biological characteristics of TFF.

Association between Promoter Polymorphisms of TFF1, TFF2, and TFF3 and the Risk of Gastric and Diffuse Gastric Cancers in a Korean Population

Gastric cancer is one of the most common cancers in the world. The aims of this study were to evaluate the association between polymorphisms in TFF gene family, TFF1, TFF2, and TFF3 and the risk of gastric cancer (GC) and GC subgroups in a Korean population via a case-control study. The eight polymorphisms in TFF gene family were identified by sequencing and genotyped with 377 GC patients and 396 controls by using TaqMan genotyping assay. The rs184432 TT genotype of TFF1 was significantly associated with a reduced risk of GC (odds ratio, [OR) = 0.45; 95% confidence interval, [CI] = 0.25-0.82; P = 0.009), more protective against diffuse-type GC (OR = 0.20; 95% CI = 0.05-0.89; P = 0.035) than GC (OR = 0.34; 95% CI = 0.14-0.82; P = 0.017) in subjects aged < 60 yr, and correlated with lymph node metastasis negative GC and diffuse-type GC (OR = 0.44; 95% CI = 0.23-0.86; P = 0.016 and OR = 0.20; 95% CI = 0.05-0.87; P = 0.031, respectively). In addition, a decreased risk of lymph node metastasis negative GC and diffuse-type GC was observed for rs225359 TT genotype of TFF1 (OR = 0.46, 95% CI = 0.24-0.88; P = 0.020 and OR = 0.21, 95% CI = 0.05-0.88; P = 0.033, respectively). These findings suggest that the rs184432 and rs225359 polymorphisms in TFF1 have protective effects for GC and contribute to the development of GC in Korean individuals.

Angiogenic and growth factors in gastric cancer

BACKGROUND

Antiangiogenic treatment is at the horizon in the palliative treatment of gastric cancer (GC), but data on proangiogenic biomarkers are still limited. The aim of this study was to analyze five proteins with a function in tumor angiogenesis: vascular endothelial growth factor (VEGF), angiopoietin-2 (Ang-2), follistatin, leptin, and platelet endothelial cell adhesion molecule 1 (CD31) in peripheral blood and corresponding tumor tissue.

MATERIAL AND METHODS

From 2008-2010, tumor tissue (n = 76) and corresponding preoperative serum (n = 69) of patients with localized GC were collected; 45 had perioperative chemotherapy. Protein serum or tumor lysate levels of these factors were measured by an angiogenesis multiplex immunoassay and correlated with response and survival.

RESULTS

Serum Ang-2 had prognostic relevance in the whole study population (P = 0.027). In subgroup analysis, serum VEGF and Ang-2 had prognostic relevance in primarily resected patients (P = 0.028; P = 0.048) but no association was found in neoadjuvantly treated patients. Follistatin concentration in the tumor tissue was associated with prognosis in all patients (P = 0.019). Tumor VEGF concentrations were correlated with histopathologic response (P = 0.011), with patients showing >50% remaining tumor having higher VEGF concentrations. The tissue Ang-2/VEGF ratio was significantly correlated with both clinical and histopathologic response (P = 0.029, P = 0.009). Additionally, the level of leptin in the tissue was associated with clinical response: nonresponding patients had higher leptin levels than those of responding patients (P = 0.032).

CONCLUSIONS

Our results show the importance of angiogenetic factors in serum and tumor tissue in GC for prognosis and treatment response. Further trials in larger patient populations are warranted for a further evaluation of proangiogenetic factors as biomarkers in gastrointestinal cancer.

Promoter hypermethylation and downregulation of trefoil factor 2 in human gastric cancer

Trefoil factor 2 (TFF2) plays a protective role in gastric mucosa and may be involved in the progression of gastric cancer, but the detailed functions and underlying molecular mechanisms are not clear. The present study used a combination of clinical observations and molecular methods to investigate the correlation between abnormal expression of TFF2 and gastric cancer progression. TFF2 expression was evaluated by reverse transcription polymerase chain reaction (RT-PCR), quantitative PCR (qPCR), and western blot and immunohistochemistry analyses. TFF2 methylation levels were analyzed by genomic bisulfite sequencing method. The results showed that TFF2 mRNA and protein expression were decreased in gastric cancer tissues compared with the matched non-cancerous mucosa, and the decreased level was associated with the differentiation and invasion of gastric cancer. Moreover, the average TFF2 methylation level of CpG sites in the promoter region was 70.4% in three gastric cancer tissues, while the level in associated non-neoplastic tissues was 41.0%. Furthermore, the promoter hypermethylation of TFF2 was also found in gastric cancer cell lines, AGS and N87, and gene expression was significantly increased following treatment with a demethylating agent, 5-Aza-2′-deoxycytidine. In conclusion, TFF2 expression was markedly decreased in gastric cancer and promoter hypermethylation was found to regulate the downregulation of TFF2. TFF2 has been suggested as a tumor suppressor in gastric carcinogenesis and metastasis.

Gastric cancer: clinical aspects, epidemiology and molecular background

The validity and usefulness of the 7th edition of the UICC tumor node metastasis classification in the context of clinical management of gastric cancer are discussed. The most relevant new agent in gastric cancer therapy is trastuzumab for HER2-positive gastric carcinomas. This marks the success of continuous effort of translational research. Trastuzumab, initially applied in palliative settings, is currently being evaluated also in neoadjuvant treatment regimens. Several new meta-analyses support the carcinogenic effect of high salt intake and smoking in the context of Helicobacter pylori infection. Further data have become available on the efficacy of protective agents, acetyl salicylic acid/nonsteroidal anti-inflammatory drugs, and antioxidants. In search for a successful prevention strategy, the focus is on the identification of individuals at high risk who demand screening (testing) and surveillance. Serological assessment of gastric mucosal abnormalities with increased risk for gastric cancer development is extensively studied, and new data are presented from Asia as well as from Europe. New high-throughput techniques combined with bioinformatic vector analysis open the gate to the identification of new potential diagnostic and therapeutic targets. Furthermore, these approaches allow us to elucidate the interplay of bacterial virulence factors and the host's immune response as well as H. pylori-associated alterations of mucosal gene expression.