Molecular Alterations in Gastric Intestinal Metaplasia

Gastric cancer (GC) remains one of the most common causes of mortality worldwide. Intestinal metaplasia (IM) is one of the preneoplastic gastric lesions and is considered an essential predisposing factor in GC development. Here we present a review of recent most relevant papers to summarize major findings on the molecular alterations in gastric IM. The latest progress in novel diagnostic methods allows scientists to identify various types of molecular alterations in IM, such as polymorphisms in various genes, changes in the expression of micro-RNAs and long noncoding RNAs, and altered microbiome profiles. The results have shown that some of these alterations have strong associations with IM and a potential to be used for screening, treatment, and prognostic purposes; however, one of the most important limiting factors is the inhomogeneity of the studies. Therefore, further large-scale studies and clinical trials with standardized methods designed by multicenter consortiums are needed. As of today, various molecular alterations in IM could become a part of personalized medicine in the near future, which would help us deliver a personalized approach for each patient and identify those at risk of progression to GC.     

Molecular Alterations in Gastric Preneoplastic Lesions and Early Gastric Cancer

Prognosis of gastric cancer is dramatically improved by early diagnosis. Correa’s cascade correlates the expression of some molecular markers with the progression of preneoplastic lesions toward carcinoma. This article reviews the diagnostic and prognostic values of molecular markers in complete (MUC2) and incomplete (MUC2, MUC5AC, and MUC6) intestinal metaplasia, gastric dysplasia/intra-epithelial neoplasia, and early gastric cancer. In particular, considering preinvasive neoplasia and early gastric cancer, some studies have demonstrated a correlation between molecular alterations and prognosis, for example, mucins phenotype in gastric dysplasia, and GATA6, TP53 mutation/LOH and MUC6 in early gastric cancer. Moreover, this review considers novelties from the literature regarding the (immuno)histochemical characterization of diffuse-type/signet ring cell gastric cancer, with particular attention to clinical outcomes of patients. The aim of this review is the evaluation of the state of the art regarding suitable biomarkers used in the pre-surgical phase, which can distinguish patients with different prognoses and help decide the best therapeutic strategy.     

Role of miR-191/425 Cluster in Tumorigenesis and Diagnosis of Gastric Cancer

Gastric cancer (GC) is among the most frequent types of cancer worldwide. Therefore, understanding the biology of GC tumorigenesis is important for appropriate diagnosis and patient surveillance. The miR-191/425 cluster has been reported to be overexpressed in various human cancers, but the tumorigenic role and clinical significance of miR-191/425 overexpression in gastric carcinogenesis is currently undefined. In this study, the expression of miR-191 and miR-425 in GC tissue and serum was assessed, and the relationship between miRNA expression and clinicopathological data was analyzed. We found that miR-191 and miR-425 were both significantly increased in human GC tissues relative to adjacent normal controls. In addition, miR-191 levels correlated with GC tumor stage and metastatic state. Furthermore, the level of serum miR-191 was significantly higher in the GC group than in the control group when using serum miR-16 as an endogenous control. Finally, inhibition of miR-191 or miR-425 in the GC cell lines HGC-27 not only reduced cell proliferation and cell cycle progression but also impaired cell migration and invasion. Taken together, our results revealed the oncogenic roles of miR-191 and miR-425 in gastric carcinogenesis, and indicated the potential use of serum miR-191 as a novel and stable biomarker for GC diagnosis.     

Gastric Adenocarcinomas and Signet-Ring Cell Carcinoma: Unraveling Gastric Cancer Complexity through Microbiome Analysis—Deepening Heterogeneity for a Personalized Therapy

Gastric cancer (GC) is the fifth most prevalent cancer worldwide and the third leading cause of global cancer mortality. With the advances of the omic studies, a heterogeneous GC landscape has been revealed, with significant molecular diversity. Given the multifaceted nature of GC, identification of different patient subsets with prognostic and/or predictive outcomes is a key aspect to allow tailoring of specific treatments. Recently, the involvement of the microbiota in gastric carcinogenesis has been described. To deepen this aspect, we compared microbiota composition in signet-ring cell carcinoma (SRCC) and adenocarcinoma (ADC), two distinct GC subtypes. To this purpose, 10 ADC and 10 SRCC and their paired non-tumor (PNT) counterparts were evaluated for microbiota composition through 16S rRNA analysis. Weighted and unweighted UniFrac and Bray–Curtis dissimilarity showed significant community-level separation between ADC and SRCC. Through the LEfSe (linear discriminant analysis coupled with effect size) tool, we identified potential microbial biomarkers associated with GC subtypes. In particular, SRCCs were significantly enriched in the phyla Fusobacteria, Bacteroidetes, Patescibacteria, whereas in the ADC type, Proteobacteria and Acidobacteria phyla were found. Overall, our data add new insights into GC heterogeneity and may contribute to deepening the GC classification.     

PD-L1 Status in Gastric Cancers,Association with the Transcriptional,Growth Factors,AKT/mTOR Components Change,and Autophagy Initiation

Introduction: The programmed death receptor ligand 1 (PD-L1) immunohistochemistry (IHC) assay is a widely used selection method for pembrolizumab treatment in gastric cancer (GC) patients. PD-L1 is the main regulator of immunity in oncogenesis. Material and methods: The study included 38 patients with GC. The combined treatment consisted of neoadjuvant FOLFOX6, or FLOT, chemotherapy and surgery. PD-L1 + tumor status was recorded in 12 patients (CPS > 5), with a negative status recorded in 26 patients. RT-PCR determined the expression of molecular markers. The level of LC3B protein was detected by Western Blotting analysis. Results: An overexpression of PD-1, PD-L2 in the tumor is associated with AKT/mTOR mRNA profile change and autophagy initiation in IHC PD-L1 positive GCs. NACT influences these biological features, modifying the expression of AKT/mTOR components and autophagic flux. In PD-L1 positive cancers, the effect of NACT and molecular markers rearrangements are essential compared to the PD-L1 negative cancers. Conclusion: The IHC PD-L1 status in gastric cancers is the significant marker of cancer progression, recovering the multiple inner mechanisms of cancer spreading and leading to ineffective therapy. Autophagy induction and angiogenesis are found in PD-L1 positive gastric cancers.     

Gastroprotective effect of selenium on ethanol-induced gastric damage in rats

In the present study, we examined the gastroprotective effect of selenium against ethanol-induced gastric mucosal lesions in rats. The gastric mucosal lesions were produced by oral administration with various concentrations of ethanol for three days, and 80% ethanol treatment was determined to be the optimal condition for induction of gastric damage. To identify the protective effect of selenium on ethanol-induced gastric damage, various doses of selenium were given as pretreatment for three days, and then gastric damage was induced by 80% ethanol treatment. Selenium showed a protective effect against ethanol-induced gastric mucosal lesions in a dose dependent manner. Specifically, 100 μg/kg selenium showed the highest level of gastroprotection. In addition, selenium markedly attenuated ethanol-induced lipid peroxidation in gastric mucosa and increased activities of radical scavenging enzymes, such as superoxide dismutase (SOD), catalase, and glutathione peroxidase in a dose-dependent manner. Histological data showed that 100 μg/kg selenium distinctly reduced the depth and severity of the ethanol induced gastric lesion. These results clearly demonstrate that selenium inhibits the formation of ethanol-induced gastric mucosal lesions through prevention of lipid peroxidation and activation of enzymatic radical scavenging.     

The Tumor Suppressor Roles of miR-433 and miR-127 in Gastric Cancer

The discovery of microRNAs (miRNAs) provides a new and powerful tool for studying the mechanism, diagnosis and treatment of human cancers. Currently, the methylation epigenetic silencing of miRNAs with tumor suppressor features by CpG island hypermethylation is emerging as a common hallmark of different tumors. Here we showed that miR-433 and miR-127 were significantly down-regulated in gastric cancer (GC) tissues compared with the adjacent normal regions in 86 paired samples. Moreover, the lower level of miR-433 and miR-127 was associated with pM or pTNM stage in clinical gastric cancer patients. The restored expression of miR-433 and miR-127 in GC cells upon 5-Aza-CdR and TSA treatment suggested the loss of miR-433 and miR-127 was at least partly regulated by epigenetic modification in GC. Furthermore, the ectopic expression of miR-433 and miR-127 in gastric cancer cell lines HGC-27 inhibits cell proliferation, cell cycle progression, cell migration and invasion by directly interacting with the mRNA encoding oncogenic factors KRAS and MAPK4 respectively. Taken together, our results showed that miR-433 and miR-127 might act as tumor suppressors in GC, and it may provide novel diagnostic and therapeutic options for human GC clinical operation in the near future.     

Mucin 1 Gene (MUC1) and Gastric-Cancer Susceptibility

Gastric cancer (GC) is one of the major malignant diseases worldwide, especially in Asia. It is classified into intestinal and diffuse types. While the intestinal-type GC (IGC) is almost certainly caused by Helicobacter pylori (HP) infection, its role in the diffuse-type GC (DGC) appears limited. Recently, genome-wide association studies (GWAS) on Japanese and Chinese populations identified chromosome 1q22 as a GC susceptibility locus which harbors mucin 1 gene (MUC1) encoding a cell membrane-bound mucin protein. MUC1 has been known as an oncogene with an anti-apoptotic function in cancer cells; however, in normal gastric mucosa, it is anticipated that the mucin 1 protein has a role in protecting gastric epithelial cells from a variety of external insults which cause inflammation and carcinogenesis. HP infection is the most definite insult leading to GC, and a protective function of mucin 1 protein has been suggested by studies on Muc1 knocked-out mice.     

Deregulated SLC2A1 Promotes Tumor Cell Proliferation and Metastasis in Gastric Cancer

Gastric cancer (GC) is one of the common reasons of cancer-related death with few biomarkers for diagnosis and prognosis. Solute carrier family 2 (facilitated glucose transporter) member 1 protein SLC2A1, also known as glucose transporter type 1 (GLUT1), has been associated with tumor progression, metastasis, and poor prognosis in many human solid tumors. However, little is reported about its clinical significance and biological functions in GC. Here we observed a strong up-regulation of SLC2A1 in patients with GC and found that SLC2A1 was significantly correlated with depth of invasion and clinical stage. Additionally, over-expression of SLC2A1 in GC cells promotes cellular proliferation and metastasis in vitro and enhances tumor growth in vivo as well as enhancement of glucose utilization. Meanwhile, elevated SLC2A1 also contributes to tumor metastasis in vitro. Our results indicate SLC2A1 exhibits a pivotal role in tumor growth, metastasis and glucose metabolism, and also suggest SLC2A1 as a promising target for gastric cancer therapy.     

Emerging Role of miRNAs in the Drug Resistance of Gastric Cancer

Gastric cancer is the third leading cause of cancer mortality worldwide. Unfortunately, most gastric cancer cases are diagnosed in an advanced, non-curable stage and with a limited response to chemotherapy. Drug resistance is one of the most important causes of therapy failure in gastric cancer patients. Although the mechanisms of drug resistance have been broadly studied, the regulation of these mechanisms has not been completely understood. Accumulating evidence has recently highlighted the role of microRNAs in the development and maintenance of drug resistance due to their regulatory features in specific genes involved in the chemoresistant phenotype of malignancies, including gastric cancer. This review summarizes the current knowledge about the miRNAs’ characteristics, their regulation of the genes involved in chemoresistance and their potential as targeted therapies for personalized treatment in resistant gastric cancer.     

Discordance Rate of HER2 Status in Primary Gastric Carcinomas and Synchronous Lymph Node Metastases: A Multicenter Retrospective Analysis

Background: The assessment of human epidermal growth factor receptor 2 (HER2) gene amplification is essential in order to identify those patients affected by advanced gastric cancer who may benefit from Trastuzumab targeted therapy. Materials and Methods: With the aim to investigate the concordance rate in HER2 status between primary gastric carcinoma (GC) and synchronous lymphnode metastases, we investigated HER2 status in a cohort of 108 surgical formalin-fixed paraffin-embedded specimens of GC and matched synchronous metastatic lymph nodes collected from three different units of Anatomic Pathology in southern of Italy. Fleiss-Cohen weighted k statistics were used to assess the concordance rate of HER2 status. Results: HER2 amplification was observed in 17% of primary GCs and the overall concordance rate with corresponding nodal metastases was 90.74%. Changes in HER2 status between primary GC and matched synchronous metastases were evidenced in 10 (9.26%) cases. Of these, 6 cases were HER2 amplified in the primary GC and not amplified in the metastases, while 4 were HER2 not amplified in the primary tumour and amplified in the lymph node metastases. Conclusions: Although at present the simultaneous determination of HER2 in advanced gastric cancer and corresponding metastatic lymph nodes is not mandatory, the possibility that the synchronous metastases of GC have a different HER2 status from that of the primary tumour is of remarkable significance; Indeed this may have influence on the therapeutic management and prognosis of the patients.     

Hedgehog Signaling Regulates the Survival of Gastric Cancer Cells by Regulating the Expression of Bcl-2

Gastric cancer is the second most common cause of cancer deaths worldwide. The underlying molecular mechanisms of its carcinogenesis are relatively poorly characterized. Hedgehog (Hh) signaling, which is critical for development of various organs including the gastrointestinal tract, has been associated with gastric cancer. The present study was undertaken to reveal the underlying mechanism by which Hh signaling controls gastric cancer cell proliferation. Treatment of gastric cancer cells with cyclopamine, a specific inhibitor of Hh signaling pathway, reduced proliferation and induced apoptosis of gastric cancer cells. Cyclopamine treatment induced cytochrome c release from mitochondria and cleavage of caspase 9. Moreover, Bcl-2 expression was significantly reduced by cyclopamine treatment. These results suggest that Hh signaling regulates the survival of gastric cancer cells by regulating the expression of Bcl-2.     

Exogenous Asymmetric Dimethylarginine (ADMA) in Pathogenesis of Ischemia-Reperfusion-Induced Gastric Lesions: Interaction with Protective Nitric Oxide (NO) and Calcitonin Gene-Related Peptide (CGRP)

Asymmetric dimethylarginine (ADMA) is an endogenous nitric oxide (NO) synthesis inhibitor and pro-inflammatory factor. We investigated the role of ADMA in rat gastric mucosa compromised through 30 min of gastric ischemia (I) and 3 h of reperfusion (R). These I/R animals were pretreated with ADMA with or without the combination of l-arginine, calcitonin gene-related peptide (CGRP) or a small dose of capsaicin, all of which are known to afford protection against gastric lesions, or with a farnesoid X receptor (FXR) agonist, GW 4064, to increase the metabolism of ADMA. In the second series, ADMA was administered to capsaicin-denervated rats. The area of gastric damage was measured with planimetry, gastric blood flow (GBF) was determined by H₂-gas clearance, and plasma ADMA and CGRP levels were determined using ELISA and RIA. ADMA significantly increased I/R-induced gastric injury while significantly decreasing GBF, the luminal NO content, and the plasma level of CGRP. This effect of ADMA was significantly attenuated by pretreatment with CGRP, l-arginine, capsaicin, or a PGE₂ analogue. In GW4064 pretreated animals, the I/R injury was significantly reduced and this effect was abolished by co-treatment with ADMA. I/R damage potentiated by ADMA was exacerbated in capsaicin-denervated animals with a further reduction of CGRP. Plasma levels of IL-10 were significantly decreased while malonylodialdehyde (MDA) and plasma TNF-α contents were significantly increased by ADMA. In conclusion, ADMA aggravates I/R-induced gastric lesions due to a decrease of GBF, which is mediated by a fall in NO and CGRP release, and the enhancement of lipid peroxidation and its pro-inflammatory properties.     

难治性胃溃疡组织中VEGF表达的检测及意义

目的研究血管内皮生长因子(VEGF)在消化性溃疡发病中的作用,探讨难治性胃溃疡的血管分子学机制。方法收集30例因难治性溃疡和并发穿孔等并发症而行胃大部切除的患者作为难治性溃疡组,取其溃疡周边和远处组织,同时收集30例首诊为胃溃疡且经胃镜证实的患者,取溃疡周边和远处组织与难治性胃溃疡组作对照进行研究。采用免疫组化法检测VEGF蛋白表达。结果难治性溃疡组周边区的VEGF阳性细胞数为36,远处区为55,对照组溃疡周边区和远处区的阳性细胞数分别为57和70,两组患者溃疡周边区和远处区VEGF阳性细胞数组间和组内比较差别均有显著性意义(P<0.01)。结论VEGF表达水平显著降低。     

Effect of a Cytoprotective Dose of Dehydroleucodine,Xanthatin, and 3-Benzyloxymethyl-5H-furan-2-one on Gastric Mucosal Lesions Induced by Mast Cell Activation

The aim of this study was to determine whether the lactones dehydroleucodine, xanthatin and 3-benzyloxymethyl-5H-furan-2-one, would be effective in an animal model of gastric ulcer induced by mast cell activation. Rats were divided into ten groups. Treatments were repeated for four days. The degree of gastric erosion was assessed with a scoring system and histological preparations. Gastric mast cell morphology was analyzed by histological procedures. Serum serotonin levels were determined as markers of mast cell activation. Statistical analyses were done using ANOVA and Tukey–Kramer test. We demonstrated that the repeated administration of compound 48/80 results in extensive mucosal lesions in the gastric mucosa and that such lesions occurred in association with mast cell degranulation and a significant increase of serum serotonin. We showed that these lesions were prevented by dehydroleucodine, xanthatin, and 3-benzyloxymethyl-5H-furan-2-one and that this effect was similar to that obtained with sodium cromoglycate. In conclusion, the results of the present study indicate that the optimal gastric cytoprotective dose of dehydroleucodine, xanthatin, and 3-benzyloxymethyl-5H-furan-2-one is efficacious in an animal model of gastric ulcer induced by mast cell activation. Our findings suggest that these lactones could be valuable tools for designing novel therapeutic agents for digestive disorders associated with inappropriate mast cell activation.     

Quantum Dots-Based Immunofluorescent Imaging of Stromal Fibroblasts Caveolin-1 and Light Chain 3B Expression and Identification of Their Clinical Significance in Human Gastric Cancer

Caveolin-1 (Cav-1) expression deficiency and autophagy in tumor stromal fibroblasts (hereafter fibroblasts) are involved in tumor proliferation and progression, particularly in breast and prostate cancer. The aim of this study was to detect the expression of fibroblastic Cav-1 and LC3B, markers of autophagy, in gastric cancer (GC) and to analyze their clinical significances. Furthermore, because Epstein-Barr virus (EBV)-associated GC (EBVaGC) is a unique subtype of GC; we compared the differential expression of fibroblastic Cav-1 and LC3B in EBVaGC and non-EBVaGC. Quantum dots (QDs)-based immunofluorescence histochemistry was used to examine the expression of fibroblastic Cav-1 and LC3B in 118 cases of GC with adequate stroma. QDs-based double immunofluorescence labeling was performed to detect the coexpression of Cav-1 and LC3B proteins. EBV-encoded small RNA was detected by QDs-based fluorescence in situ hybridization to identify EBVaGC. Multivariate analysis indicated that low fibroblastic Cav-1 level was an independent prognosticator (p = 0.029) that predicted poorer survival of GC patients. Positive fibroblastic LC3B was correlated with lower invasion (p = 0.032) and was positively associated with Cav-1 expression (r = 0.432, p < 0.001). EBV infection did not affect fibroblastic Cav-1 and LC3B expression. In conclusion, positive fibroblastic LC3B correlates with lower invasion, and low expression of fibroblastic Cav-1 is a novel predictor of poor GC prognosis.     

Frequent gene amplification predicts poor prognosis in gastric cancer

Gastric cancer is one of the most common malignancies worldwide. However, genetic alterations leading to this disease are largely unknown. Gene amplification is one of the most frequent genetic alterations, which is believed to play a major role in the development and progression of gastric cancer. In the present study, we identified three frequently amplified genes from 30 candidate genes using real-time quantitative PCR method, including ERBB4, C-MET and CD44, and further explored their association with clinicopathological characteristics and poor survival in a cohort of gastric cancers. Our data showed amplification of these genes was significantly associated with certain clinicopathological characteristics, particularly tumor differentiation and cancer-related death. More importantly, amplification of these genes was significantly related to worse survival, suggesting that these amplified genes may be significant predictors of poor prognosis and potential therapeutic targets in gastric cancer. Targeting these genes may thus provide new possibilities in the treatment of gastric cancer.     

Tumor-Associated Macrophages and Inflammatory Microenvironment in Gastric Cancer: Novel Translational Implications

Gastric cancer (GC) represents the fifth most frequently diagnosed cancer worldwide, with a poor prognosis in patients with advanced disease despite many improvements in systemic treatments in the last decade. In fact, GC has shown resistance to several treatment options, and thus, notable efforts have been focused on the research and identification of novel therapeutic targets in this setting. The tumor microenvironment (TME) has emerged as a potential therapeutic target in several malignancies including GC, due to its pivotal role in cancer progression and drug resistance. Therefore, several agents and therapeutic strategies targeting the TME are currently under assessment in both preclinical and clinical studies. The present study provides an overview of available evidence of the inflammatory TME in GC, highlighting different types of tumor-associated cells and implications for future therapeutic strategies.