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Gastric cancer is the third leading cause of cancer death with 5-year survival rate of about 30-35%. Since early detection is associated with decreased mortality, identification of novel biomarkers for early diagnosis and proper management of patients with the best response to therapy is urgently needed. Long noncoding RNAs (lncRNAs) due to their high specificity, easy accessibility in a noninvasive manner, as well as their aberrant expression under different pathological and physiological conditions, have received a great attention as potential diagnostic, prognostic, or predictive biomarkers. They may also serve as targets for treating gastric cancer. In this review, we highlighted the role of lncRNAs as tumor suppressors or oncogenes that make them potential biomarkers for the diagnosis and prognosis of gastric cancer. Relatively, lncRNAs such as H19, HOTAIR, UCA1, PVT1, tissue differentiation-inducing nonprotein coding, and LINC00152 could be potential diagnostic and prognostic markers in patients with gastric cancer. Also, the impact of lncRNAs such as ecCEBPA, MLK7-AS1, TUG1, HOXA11-AS, GAPLINC, LEIGC, multidrug resistance-related and upregulated lncRNA, PVT1 on gastric cancer epigenetic and drug resistance as well as their potential as therapeutic targets for personalized medicine was discussed.

Gastric cancer (GC) is one of the most common causes of cancer-related death in the world, with multiple genetic and epigenetic alterations involved in disease development. CYLD tumor suppressor gene encodes a multifunctional deubiquitinase which negatively regulates various signaling pathways. Deregulation of this gene has been found in different types of cancer. This study aimed to evaluate for the first time the CpG island methylation pattern of CYLD gene promoter, and its expression level in gastric adenocarcinoma. CYLD messenger RNA expression and promoter methylation in 53 tumoral and their non-neoplastic counterpart tissues were assessed using quantitative polymerase chain reaction and bisulfite sequencing. Also, we investigated the impacts of the infectious agents including Helicobacter pylori (H. pylori), EBV, and CMV on CYLD expression and promoter methylation in GC. Results showed that the expression level of CYLD was downregulated in GC, and was significantly associated with gender (female), patient's age (

Gastric cancer risk is higher for malignancies motivated by bacterial and viral infections. Epigenetic abnormalities including DNA methylation, histone modifications, and noncoding RNAs are important regulatory key players in gastric cancer development in infected patients. Epigenetic memory restoration is an extremely interesting phenomenon which should be considered in therapeutic approaches. In vitro and in vivo antiviral treatments in combination with epigenetic therapeutic strategies along with standard chemotherapy revealed promising outcomes in gastric cancer prevention and treatment. This review summarizes our current understanding of the gastric cancer infections and epigenetic alterations caused by these agents. We focus on studies highlighting recent advances in epigenetic restoration by target specific drugs and present also a comprehensive overview of effective antiviral drug treatments against gastric cancer.

Helicobacter pylori and Epstein-Barr virus are well established infections for gastric cancer development. However, the role of cytomegalovirus alone or in combination with other infections is unclear. In this case-control study, the prevalence of different infections was evaluated, and their frequency was compared with clinicopathologic features among gastric cancer patients and normal volunteers from 2012 to 2017. Approximately two-thirds (61.9%) of the gastric cancer patients had at least 1 viral infection, while viral infection prevalence in normal volunteers was only 4.7% (P = 0.021). The higher infection frequency in gastric cancer patients was observed for EBV (49.2%). No CMV DNA was detected in normal volunteers. In contrast, one-fourth of the gastric cancer patients were infected with CMV. Furthermore, CMV frequency in tumoral tissues (68.75%) was significantly higher than in nontumoral tissues (12.5%) (P = 0.0311). Although H. pylori infection was significantly lower in tumoral tissues than in nontumoral tissues (P = 0.0136), all tumoral tissues had cagA, while only 61.5% of nontumoral tissues were cagA positive. CMV-infected patients were affected 14 years earlier than uninfected, and CMV-negative patients (mean age = 56 vs. 69 and 70 years; P= 7.6×10-3 and P = 2.7×10-4, respectively). Also, EBV viral load in earlier grades and stages was more than 100-fold higher than advanced grades and stages. Our results show a high level of infections in gastric cancer. The association of these infections especially with CMV contributes to gastric adenocarcinoma development at earlier age.

Gastric cancer is a life-threatening disease; resulting from interaction among genetic, epigenetic, and environmental factors. Aberrant dysregulation and methylation changes in Wnt/β-catenin signaling downstream elements are a prevalent phenomenon encountered in gastric tumorigenesis. Also, viral infections play a role in gastric cancer development. CTNNBIP1 (β-catenin interacting protein 1) gene is an antagonist of Wnt signaling which binds to the β-catenin molecules. The CTNNBIP1 function as tumor suppressor gene or oncogene in different types of cancer is controversial. Moreover, its function and regulatory mechanisms in gastric cancer progression is unknown. In the present study, we examined CTNNBIP1 gene expression, the methylation status of the regulatory region of the gene, and their association with Epstein-Barr virus (EBV), and cytomegalovirus (CMV) and Helicobacter pylori infections in human gastric adenocarcinoma tissues in comparison with their adjacent nontumoral tissues. Our data revealed a significant downregulation of CTNNBIP1 in gastric tumors. Female patients showed lower level of CTNNBIP1 than males (p < 0.05). Also, decreased expression of CTNNBIP1 was markedly associated with well-differentiated tumor grades (p < 0.05). No methylation change was observed between tumoral and nontumoral tissues. Additionally, CTNNBIP1 down regulation was significantly associated with CMV infection (p < 0.05). In the absence of EBV infection, lower expression of CTNNBIP1 was observed. There was no association between H. pylori infection and CTNNBIP1 expression. Our findings revealed the tumor suppressor role for CTNNBIP1 in gastric adenocarcinoma. Interestingly, EBV and CMV infections modulate CTNNBIP1 expression.