CDX1/2 and KLF5 Expression and Epigenetic Modulation of Sonic Hedgehog Signaling in Gastric Adenocarcinoma.

Gastric cancer is among the commonplace causes of cancer death worldwide. Sonic hedgehog (Shh) signaling is an important pathway which may be dysregulated in many cancers.CDX1/2, and KLF5are key transcription factors involved in Shh pathway and cancer stem cells. The aim of this study was to investigate the expression and epigenetic alterations of these genes in gastric cancer patients. DNA methylation's modifications of CDX1, KLF5 and CDX2 genes alongside with the expressions of these genes in gastric cancer tissues and their non-tumoral counterparts (margin tissues) were analyzed using methylation specific sequencing, and Real time PCR Taq man assays, respectively. The expression of CDX1 (P = 0.002) and KLF5 (P = 0.010) were decreased significantly, but it was considerably increased for CDX2 (P = 0.001). Relatively, the results for the regulatory region methylation status of each CpG site had shown a notable fluctuation in these genes with no significant difference in most places. The creation of metastatic lymph nodes in patients was significantly associated with increased expression of CDX2 gene. The modifications of these genes expression can be considered as a cancer biomarker in future studies. Methylation of the investigated genes is not the main mechanism of gastric cancer development.

Epigenetic alterations of CYLD promoter modulate its expression in gastric adenocarcinoma: A footprint of infections.

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 (<60), high grade, and no lymph-node metastasis (p = 0.001, 0.002, 0.03, and 0.003, respectively). Among the 31 analyzed CpG sites located in about 600 bp region within the promoter, two CpG sites were hypermethylated in GC tissues. We also found a significant inverse association between DNA promoter methylation and CYLD expression (p = 0.02). Furthermore, a direct association between H. pylori, EBV, and CMV infections with hypermethylation and reduced CYLD expression was observed (p = 0.04, 0.03, and 0.03, respectively). Our findings indicate that CYLD is downregulated in GC. Infectious agents may influence CYLD expression.

CTNNBIP1 downregulation is associated with tumor grade and viral infections in gastric adenocarcinoma.

Gastric cancer is a life-threatening disease; resulting from interaction among genetic, epigenetic, and environmental factors. Aberrant dysregulation and methylation changes in Wnt/ß-catenin signaling downstream elements are a prevalent phenomenon encountered in gastric tumorigenesis. Also, viral infections play a role in gastric cancer development. CTNNBIP1 (ß-catenin interacting protein 1) gene is an antagonist of Wnt signaling which binds to the ß-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.

DNA methyltransferases and gastric cancer: insight into targeted therapy.

Gastric cancer is a major health problem worldwide occupying most frequent causes of cancer-related mortality. In addition to genetic modifications, epigenetic alterations catalyzed by DNA methyltransferases (DNMTs) are a well-characterized epigenetic hallmark in gastric cancer. The reversible nature of epigenetic alterations and central role of DNA methylation in diverse biological processes provides an opportunity for using DNMT inhibitors to enhance the efficacy of chemotherapeutics. In this review, we discussed key factors or mechanisms such as SNPs, infections and genetic modifications that trigger DNMTs level modification in gastric cancer, and their potential roles in cancer progression. Finally, we focused on how inhibitors of the DNMTs can most effectively be used for the treatment of gastric cancer with multidrug resistance.

Prevalence of multiple infections and the risk of gastric adenocarcinoma development at earlier age.

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.

Coinheritance of Sicilian (뫧)0-Thalassemia and Two Rare Hemoglobin Variants: A Complex Case of Hemoglobinopathy.

α-Thalassemia (α-thal) is considered as the most common inherited hemoglobin disorder worldwide. The present study describes the first observation of a combination of rare α-chain variants, and ß-globin gene cluster deletion. A 21-year-old woman with thalassemia trait, marked microcytosis, mild anemia, and normal range of Hb F was referred to Amirkola genetic center in the North of Iran for routine molecular test of thalassemia in the context of carrier detection and prevention of thalassemia major birth. Nucleotide sequencing revealed a novel compound heterozygosity status for two non-deletional mutations on HBA2, Hb O Indonesia (α116(GH4)Glu â†’ Lys), and Hb Matsue-Oki (α75 (EF4) Asp â†’ Asn), together with heterozygosity for the sicilian (δß)0-thal mutation. This finding highlights the necessity of deep molecular investigation of thalassemia in regions where thalassemia is abundant, and present highly heterogeneous population.

Hedgehog signaling pathway: Epigenetic regulation and role in disease and cancer development.

The evolutionarily conserved Hedgehog (Hh) signaling pathway have critical roles in development and homeostasis of tissues. Under physiological conditions, Hh is controlled at different levels via stem cell maintenance and tissue regeneration. Aberrant activation of this signaling pathway may occur in a wide range of human diseases including different types of cancer. In this review we present a concise overview on the key genes composing Hh signaling pathway and provide recent advances on the molecular mechanisms that regulate Hh signaling pathway from extracellular and receptors to the cytoplasmic and nuclear machinery with a highlight on the role of microRNAs. Furthermore, we focus on critical studies demonstrating dysregulation of the Hh pathway in human disease development, and potential therapeutic implications. Finally, we introduce recent therapeutic drugs acting as Shh signaling pathway inhibitors, including those in clinical trials and preclinical studies.

Application of unique sequence index (USI) barcode to gene expression profiling in gastric adenocarcinoma.

Accurate expression profiling is imperative for understanding the biological roles of mRNAs. Real-time PCR have been at the forefront of biological innovation in detection and monitoring of gene expression, however, fluorophore-labeled oligonucleotides and double-stranded DNA binding dyes, the two most frequently used dyes in RNA detection, are not very cost effective and have poor specificity, respectively. We have developed a cost effective and specific approach for mRNA expression profiling via added unique sequence index (USI) to cDNAs before amplification. USI is a barcode which enable the detection of each target RNA. Using this method, caudal type homeobox 1 (CDX1) and FAT atypical cadherin 4 (FAT4) expressions were investigated in tumoral and non-tumoral tissues of gastric cancer patients and compared with commercial ABI kit. Both methods indicated that FAT4 and CDX1 expression were significantly reduced in gastric cancer tissues compared with adjacent noncancerous tissues. Moreover, we have shown that this assay is highly sensitive, linear and reproducible. USI barcode not only provides a powerful tool for mRNA detection due to its sensitivity, specificity and cost-effectiveness, but also allows comfortable design for real-time qPCR assays within the least time and empowers the analysis of many transcripts of virtually any organism. Furthermore, USI barcode is highly affordable for large numbers of different samples or small sample sizes without microarray and expensive commercial platforms.

FAT4 hypermethylation and grade dependent downregulation in gastric adenocarcinoma.

Gastric cancer is one of the major causes of death due to cancer in the world. It is a multi-factorial disease with epigenetic factors being also involved in its development. FAT4 is a tumor suppressor gene exerting an important role in cell adhesion. This study aimed at analyzing FAT4 expression and promoter methylation in gastric cancer. FAT4 expression was studied in 30 tumoral tissues and their non-tumoral counterparts using Taqman real time PCR method. Promoter methylation was assessed using bisulfite conversion method followed by sequencing. Tumor tissues showed reduced FAT4 expression (P = 0.04). FAT4 downregulation was associated with tumor grade, with higher repression at advanced grades. Significant increase of promoter methylation was observed in tumoral tissues. Reduced expression of FAT4 and increased methylation of its promoter may be one of the effective processes in turning a healthy stomach tissue into a tumor tissue.