Association between Virulence Factors and TRAF1/4-1BB/Bcl-xL Expression in Gastric Mucosa Infected with Helicobacter pylori

Primary antibiotic resistance and its relationship with cagA and vacA genes in Helicobacter pylori isolates from Algerian patients

The epidemiology of Helicobacter pylori resistance to antibiotics is poorly documented in Africa and especially in Algeria. The aim of our study was to determine the antibiotic resistance rates, as well as its possible relationship with VacA and CagA virulence markers of isolates from Algerian patients. One hundred and fifty one H. pylori isolate were obtained between 2012 and 2015 from 200 patients with upper abdominal pain. Antimicrobial susceptibility testing was performed for amoxicillin, clarithromycin, metronidazole, ciprofloxacin, rifampicin and tetracycline. Molecular identification of H. pylori and the detection of vacA and cagA genes were performed using specific primers. We found that H. pylori was present in 83.5% of collected biopsies, 54.9% of the samples were cagA positive, 49.67% were vacA s1m1, 18.30% were vacA s1m2 and 25.49% were vacA s2m2. Isolates were characterized by no resistance to amoxicillin (0%), tetracycline (0%), rifampicin (0%), a high rate of resistance to metronidazole (61.1%) and a lower rate of resistance to clarithromycin (22.8%) and ciprofloxacin (16.8%). No statically significant relationship was found between vagA and cagA genotypes and antibiotic resistance results (p > 0.5) except for the metronidazole, which had relation with the presence of cagA genotype (p = 0.001).

CagA promotes proliferation and inhibits apoptosis of GES-1 cells by upregulating TRAF1/4-1BB

Cytotoxin-associated gene A (CagA) is one of the most important virulence factors of Helicobacter pylori, and serves a role in H. pylori‑mediated tumorigenesis in gastric cancer. However, the underlying molecular mechanism remains to be elucidated. The present study aimed to investigate the effects of CagA on the proliferation and apoptosis of GES‑1 cells, and the underlying mechanism. A CagA eukaryotic expression plasmid was constructed and transfected into GES‑1 cells. The mRNA and protein levels of CagA, tumor necrosis factor receptor‑associated factor 1 (TRAF1) and tumor necrosis factor receptor superfamily member 9 (4‑1BB) were determined using the reverse transcription‑quantitative polymerase chain reaction and western blot analysis, respectively. Western blot and ELISA analysis was used to detect the release of interleukin (IL)‑8. An MTT assay and flow cytometric analysis was used to assess cell viability and apoptosis, respectively. Ectopic expression of CagA markedly increased TRAF1 and 4‑1BB mRNA and protein levels in GES‑1 cells. CagA increased the expression and release of IL‑8 in GES‑1 cells. The expression of CagA significantly promoted the proliferation (P<0.05) and inhibited the apoptosis (P<0.05) of GES‑1 cells. In conclusion, CagA upregulated TRAF1/4‑1BB, thereby promoting the proliferation and inhibiting the apoptosis of GES-1 cells.

Relationship between vacA Types and Development of Gastroduodenal Diseases

The Helicobacter pylori vacuolating cytotoxin (VacA) is a secreted pore-forming toxin and a major virulence factor in the pathogenesis of H. pylori infection. While VacA is present in almost all strains, only some forms are toxigenic and pathogenic. While vacA and its genotypes are considered as markers of H. pylori-related diseases or disorders, the pathophysiological mechanisms of VacA and its genotypes remain controversial. This review outlines key findings of publications regarding vacA with emphasis on the relationship between vacA genotypes and the development of human disease.

Role of Helicobacter pylori infection in pathogenesis of gastric carcinoma

Gastric cancer (GC) is one of the most common carcinoma and the second leading cause of cancer-related deaths worldwide. Helicobacter pylori (H. pylori) infection causes a series of precancerous lesions like gastritis, atrophy, intestinal metaplasia and dysplasia, and is the strongest known risk factor for GC, as supported by epidemiological, preclinical and clinical studies. However, the mechanism of H. pylori developing gastric carcinoma has not been well defined. Among infected individuals, approximately 10% develop severe gastric lesions such as peptic ulcer disease, 1%-3% progresses to GC. The outcomes of H. pylori infection are determined by bacterial virulence, genetic polymorphism of hosts as well as environmental factors. It is important to gain further understanding of the pathogenesis of H. pylori infection for developing more effective treatments for this common but deadly malignancy. The recent findings on the bacterial virulence factors, effects of H. pylori on epithelial cells, genetic polymorphism of both the bacterium and its host, and the environmental factors for GC are discussed with focus on the role of H. pylori in gastric carcinogenesis in this review.

Challenges of deciphering gastric cancer heterogeneity

Gastric cancer is in decline in most developed countries; however, it still accounts for a notable fraction of global mortality and morbidity related to cancer. High-throughput methods are rapidly changing our view and understanding of the molecular basis of gastric carcinogenesis. Today, it is widely accepted that the molecular complexity and heterogeneity, both inter- and intra-tumour, of gastric adenocarcinomas present significant obstacles in elucidating specific biomarkers for early detection of the disease. Although genome-wide sequencing and gene expression studies have revealed the intricate nature of the molecular changes that occur in tumour landscapes, the collected data and results are complex and sometimes contradictory. Several aberrant molecules have already been tested in clinical trials, although their diagnostic and prognostic utilities have not been confirmed thus far. The gold standard for the detection of sporadic gastric cancer is still the gastric endoscopy, which is considered invasive. In addition, genome-wide association studies have confirmed that genetic variations are important contributors to increased cancer risk and could participate in the initiation of malignant transformation. This hypothesis could in part explain the late onset of sporadic gastric cancers. The elaborate interplay of polymorphic low penetrance genes and lifestyle and environmental risk factors requires additional research to decipher their relative impacts on tumorigenesis. The purpose of this article is to present details of the molecular heterogeneity of sporadic gastric cancers at the DNA, RNA, and proteome levels and to discuss issues relevant to the translation of basic research data to clinically valuable tools. The focus of this work is the identification of relevant molecular changes that could be detected non-invasively.