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.

Gastric cancer is the leading cause of cancer-related mortality worldwide. Given the importance of gastric cancer in public health, identifying biomarkers associated with disease onset is an important part of precision medicine. The hedgehog signaling pathway is considered as one of the most significant widespread pathways of intracellular signaling in the early events of embryonic development. This pathway contributes also to the maintenance of pluripotency of cancer stem cells pluripotency. In this study, we analyzed the expression levels of sonic hedgehog (Shh) signaling pathway genes IHH, BOC, RAB23a and their regulatory miRNAs including MIR-195-5p, MIR-509-3-5p, MIR-6738-3p in gastric cancer patients. In addition, the impact of infection status on the expression level of those genes and their regulatory miRNAs was investigated. One hundred samples taken from 50 gastric cancer patients (50 tumoral tissues and their adjacent non-tumoral counterparts) were included in this study. There was a significant difference in all studied genes and miRNAs in tumoral tissues in comparison with their adjacent non-tumoral counterparts. The lower expression of IHH, BOC, RAB23, miR-195-5p, and miR-6738-3p was significantly associated with more advanced cancer stage. Additionally, IHH upregulation was significantly associated with CMV infection (P < 0.001). Also, receiver operating characteristic (ROC) curve analysis indicated that mir-195 was significantly related to several clinicopathological features including tumor stage, grade, age, gender, and infection status of gastric cancer and can be considered as a potential diagnostic biomarker for gastric cancer. This study confirms the important role of Shh signaling pathway genes in gastric cancer tumorigenesis and their potential as novel molecular biomarkers and therapeutic targets.

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