A Genetic and Immunohistochemical Analysis of Helicobacter pylori Phenotypes and p27 Expression in Adenocarcinoma Patients in Jordan

Stomach (gastric) cancer is one of the most prevalent and deadly cancers worldwide and most gastric cancers are adenocarcinomas. Based on prior research, there is an association between Helicobacter pylori (H. pylori) infection together with the frequency of duodenal ulcer, distal gastric adenocarcinoma, mucosa-associated lymphoid tissue (MALT) lymphoma, and antral gastritis. Helicobacter pylori virulence and toxicity factors have been identified before that significantly influence the clinical outcomes of H. pylori infection and gastric adenocarcinoma. However, it remains unclear exactly how different strains of H. pylori affect gastric adenocarcinoma. Current research suggests this involves tumor suppressor genes, like p27 but also H. pylori toxic virulence proteins. Therefore, we quantified known H. pylori genotypes within adenocarcinoma patients to establish the prevalence of known toxins that include cytotoxin-associated gene A (cagA) as well as vacuolating cytotoxin A (vacA) within patients of variable adenocarcinoma diagnosis. This analysis used gastrectomy samples validated for DNA viability. The incidence of H. pylori in adenocarcinoma patients in Jordan was established to be 54.5% positive (ureA gene positive) with cagA genotype occurrence at 57.1%, but also in this population study vacA gene ratios found to be 24.7%:22.1%:14.3%:14.3%. (vacAs1:vacAs2:vacAm1:vacAm2). Using immunohistochemistry (IHC), we confirmed with statistical significance that p27 was dysregulated and suppressed, within nearly all H. pylori vacA genotypes. In addition, within 24.6% of H. pylori samples analyzed was a different bacterial genotype, and curiously that p27 protein expression was retained in 12% of tested adenocarcinoma H. pylori samples. This is suggestive that p27 could be used as a prognostic indicator but also that an unknown genotype could be contributing to the regulatory effects of p27 protein within this bacterial and cellular environment that may include other virulence factors and unknown immune system regulatory changes.

PLK2 Single Nucleotide Variant in Gastric Cancer Patients Affects miR-23b-5p Binding

PURPOSE

Chromosomal instability is a hallmark of gastric cancer (GC). It can be driven by single nucleotide variants (SNVs) in cell cycle genes. We investigated the associations between SNVs in candidate genes, PLK2, PLK3, and ATM, and GC risk and clinicopathological features.

MATERIALS AND METHODS

The genotyping study included 542 patients with GC and healthy controls. Generalized linear models were used for the risk and clinicopathological association analyses. Survival analysis was performed using the Kaplan-Meier method. The binding of candidate miRs was analyzed using a luciferase reporter assay.

RESULTS

The PLK2 Crs15009-Crs963615 haplotype was under-represented in the GC group compared to that in the control group (Pcorr=0.050). Male patients with the PLK2 rs963615 CT genotype had a lower risk of GC, whereas female patients had a higher risk (P=0.023; P=0.026). The PLK2 rs963615 CT genotype was associated with the absence of vascular invasion (P=0.012). The PLK3 rs12404160 AA genotype was associated with a higher risk of GC in the male population (P=0.015). The ATM Trs228589-Ars189037-Grs4585 haplotype was associated with a higher risk of GC (P<0.001). The ATM rs228589, rs189037, and rs4585 genotypes TA+AA, AG+GG, and TG+GG were associated with the absence of perineural invasion (P=0.034). In vitro analysis showed that the cancer-associated miR-23b-5p mimic specifically bound to the PLK2 rs15009 G allele (P=0.0097). Moreover, low miR-23b expression predicted longer 10-year survival (P=0.0066) in patients with GC.

CONCLUSIONS

PLK2, PLK3, and ATM SNVs could potentially be helpful for the prediction of GC risk and clinicopathological features. PLK2 rs15009 affects the binding of miR-23b-5p. MiR-23b-5p expression status could serve as a prognostic marker for survival in patients with GC.

Early and late genome-wide gastric epithelial transcriptome response during infection with the human carcinogen Helicobacterpylori

Infection of the stomach by Helicobacter pylori is a major risk factor for the development of gastric cancer. Colonization of the gastric epithelium leads to the activation of multiple disease-related signaling pathways. Serine protease HtrA represents an important secreted virulence factor that mediates cleavage of cellular junctions. However, its potential role in nuclear responses is unknown. Here, we performed a genome-wide RNA-seq analysis of polarized gastric epithelial cells infected by wild-type (wt) and ΔhtrA mutant bacteria. Fluorescence microscopy showed that H. pylori wt, but not ΔhtrA bacteria, preferably localized at cellular junctions. Our results pinpointed early (2 h) and late (6 h) transcriptional responses, with most differentially expressed genes at 6 h post infection. The transcriptomes revealed HtrA-dependent targeting of genes associated with inflammation and apoptosis (e.g. IL8, ZFP36, TNF). Accordingly, infection with the ΔhtrA mutant induced increased apoptosis rates in host cells, which was associated with reduced H. pylori CagA expression. In contrast, transcription of various carcinogenesis-associated genes (e.g. DKK1, DOCK8) was affected by H. pylori independent of HtrA. These findings suggest that H. pylori disturbs previously unknown molecular pathways in an HtrA-dependent and HtrA-independent manner, and provide valuable new insights of this significant pathogen in humans and thus potential targets for better controlling the risk of malignant transformation.

Helicobacter pylori CagA EPIYA Motif Variations Affect Metabolic Activity in B Cells

Background: Helicobacter pylori (Hp) colonizes the human stomach and can induce gastric cancer and mucosa-associated lymphoid tissue (MALT) lymphoma. Clinical observations suggest a role for the Hp virulence factor cytotoxin-associated gene A (CagA) in pathogenesis. The pathogenic activity of CagA is partly regulated by tyrosine phosphorylation of C-terminal Glu-Pro-Ile-Tyr-Ala (EPIYA) motifs in host cells. However, CagA differs considerably in EPIYA motifs, whose functions have been well characterized in epithelial cells. Since CagA is fragmented in immune cells, different CagA variants may exhibit undetected functions in B cells. Methods: B cells were infected with Hp isolates and isogenic mutants expressing different CagA EPIYA variants. CagA translocation and tyrosine phosphorylation were investigated by Western blotting. Apoptosis was analyzed by flow cytometry and metabolic activity was detected by an MTT assay. Results: Isogenic CagA EPIYA variants are equally well translocated into B cells, followed by tyrosine phosphorylation and cleavage. B cell apoptosis was induced in a CagA-independent manner. However, variants containing at least one EPIYA-C motif affected metabolic activity independently of phosphorylation or multiplication of EPIYA-C motifs. Conclusions: The diverse structure of CagA regulates B cell physiology, whereas B cell survival is independent of CagA.

Vaccine development against Helicobacter pylori: from ideal antigens to the current landscape

Introduction: The interest of the world scientific community for an effective vaccine against Helicobacter pylori infection arises from its high prevalence and association with many diseases. Moreover, with an immunological response that is not always effective for the eradication of the bacteria and an increasing antibiotic resistance in the treatment of this infection, the search for a vaccine and new therapeutic modalities to control this infection is urgent.Areas covered: We bring an overview of the infection worldwide, discussing its prevalence, increasing resistance to antibiotics used in its therapy, in addition to the response of the immune system to the infection registered so far. Moreover, we address the most used antigens and their respective immunological responses expected or registered up to now. Finally, we address the trials and their partial results in development for such vaccines.Expert opinion: Although several studies for the development of an effective vaccine against this pathogen are taking place, many are still in the preclinical phase or even without updated information. In this sense, taking into account the high prevalence and association with important comorbidities, the interest of the pharmaceutical industry in developing an effective vaccine against this pathogen is questioned.