Multiple Repeats of Helicobacter pylori CagA C-Terminal Motifs Predict the Risk of Gastric Cancer in Iran

Background: CagA, a 120- to 145-kD Helicobacter pylori [H. pylori] protein, increases the risk of atrophic gastritis and gastric cancer [GC]. The pathogenic CagA contains a highly polymorphic Glu-Pro-Ile-Tyr-Ala [EPIYA] repeat region in the C-terminal portion of the protein. The aim of this study was to determine the number and type of EPIYA [glutamine-proline-isoleucine-tyrosine-alanine] motifs within the cagA 3' variable region among H. pylori isolates and their association with GC.

Materials and methods: The total number of 206 individuals [170 controls and 36 patients with GC] referring to the endoscopy units of several cities in Iran [2008-2014] were recruited. The polymerase chain reaction [PCR] amplification was performed to determine the presence of H. pylori, cagA gene, and EPIYA motifs.

Results: In this study, 81 [47.6 percent] and 22 [61.1 percent] of the controls and patients with GC were carriers of cagA+ strains, respectively. The overall frequency of EPIYA-AB, EPIYA-ABC, EPIYA-ABCC, and EPIYA-ABCCC in patients with GC were 0 percent, 59 percent, 9 percent, and 31.8 percent, respectively. The results of regression analysis showed a significant association between EPIYA-ABCCC motif and the risk of GC [OR = 9.99 [95 percentCI: 2.17-45.88], p = 0.003].

Conclusion: We propose that patients infected with H. pylori strains harboring more than one CagA EPIYA C motif [EPIYA-ABCCC] have an increased risk of GC, thus, testing for this genotype may have clinical usefulness

[New-generation monoclonal antibodies and inhibitors in the treatment of gastric cancer: recent findings and future perspectives]

Gastric cancer [GC] is the fourth most common disease worldwide and approximately one million people are diagnosed as having gastric adenocarcinoma. Each year, nearly 700,000 people lose their lives because of GC. Several altered molecular pathways are involved in the pathogenesis of GC, which can be targeted by specific monoclonal antibodies [mAbs]. In recent years, the use of mAbs has provided considerable success in the treatment of cancer. Such mAbs are laboratory-produced molecules that incur changes to precisely bind to specific sites. These drugs are similar to naturally produced antibodies as part of our immune system's response. They play an important role in the treatment of many diseases, such as the different types of cancer. In cancer therapy, bispecific antibodies are used for targeting immune effector cells to destruct tumor cells [cancer immunotherapy] or neutralize two different pathways through inactivation on the level of either receptors or ligands. It seems that the development of this type of therapeutic agents to effectively treat a variety of cancers such as GC, is inevitable. The aim of the present study was to describe molecular-targeted therapy by using new-generation mAbs and inhibitors for the treatment of GC

[Relationship between common KRAS gene mutations and clinicopathological features of patients with colorectal cancer in Isfahan, Iran]

Background: colorectal cancer [CRC] is one of the most common gastrointestinal cancers worldwide. KRAS mutations are found in 20-30% of the cases and are associated with poor response to anti-EGFR therapies. Mutations in the KRAS gene induce the constitutive protein activity by eliminating the GTPase activity in the signal transduction pathway. Somatic mutations of KRAS are located up to 90% in codons 12 and 13 of exon 2. Therefore, this study evaluated the association between KRAS mutations and clinicopathological features of patients with CRC in Isfahan

Materials and Methods: this study was performed on 52 patients with CRC referred to Al-Zahra Hospital in Isfahan. Total DNA was extracted from fresh tumor and normal tissues. The exon 2 of KRAS gene was amplified and sequenced for detection of the point mutations. After mutation analysis, the clinical and pathological associations of mutant genes were assessed

Results: the prevalence of KRAS gene mutation was 15/4% [8 out of the 52 cases]. Six mutations found in codon 12 [75%], were G12D and G12A, and two mutations found in codon 13 [25%] were G13D. Common tumor sites were rectum and rectosigmoid. The mean age of the patients was 61/2+/-13/9 years [range: 31-87 years]. There was no significant relationship between the mutations and clinicopathological features of patients with CRC [p>0.05]

Conclusion: this paper presents new results on the frequency of KRAS mutations in patients with CRC. KRAS mutations could be used as molecular biomarkers to predict the lack of response to anti-EGFR monoclonal antibodies

[Long non-coding RNAs as novel biomarkers of gastric cancer]

Gastric cancer [GC] is the second leading cause of cancer-related deaths worldwide. Long non-coding RNAs [LncRNAs], a small class of molecules that are transcribed as non-coding RNAs with lengths ranging from [200 nt to 100 kb have no protein coding capacity. Ectopic expression of LncRNAs, plays an important role in the development of GC. These molecules are involved in physiological cellular processes such as genomic imprinting, X-chromosome inactivation, maintenance of pluripotency and organogenesis through making changes in chromatin, transcription, translation, and processing. It has been known that LncRNAs act as oncogenes or tumor suppressor genes. Some studies show that LncRNAs could interact with miRNA and block miRNA access to their mRNA targets. Recent studies have shown that LncRNAs involve in tumorigenesis, angiogenesis, proliferation, migration and differentiation, and apoptosis. They can be used as novel biomarkers for the early detection of GC as well as therapeutic targets. In this study we aimed to describe the latest findings about the role of LncRNAs in the development of GC

[Helicobacter pylori infection and stem cells: two main factors at the origin of gastric cancer]

Helicobacter pylori was the main cause of gastric cancer [GC] in all over the world that results in intestinal- and diffuse-type carcinoma. Infection by this bacterium remains chronic for a long time. In vitro studies have highlighted the role of stem cells in GC. H. pylori infection results in tissue injury and the adult/tissue stem cells subsequently start to replace the dead cells. The genetic alteration within those cells may be the cause of development of GC, suggesting cancerous cells in the stomach are derived from tissue stem cells. Studies have proved that the bone marrow-derived mesenchymal stem cells [BM-MSCs] take part in repair of the injured gastric tissue. When there was injury, the BM-MSCs migrate from bone marrow and participate in the repair of injured tissue that results in the progression of GC. Cancer stem cells [CSCs] harbor markers, targeting these markers via nano-drug systems can be used for GC therapy

Relevance of helicobacter pylori plasticity and cagPAI regions known genes to gastric and duedenal ulcers in Iran

Background: Helicobacter pylori [H. pylori] is the main cause of gastroduodenal diseases, such as chronic atrophic gastritis, gastric ulcer [GU], and duodenal ulcer [DU]. There is a close relationship between H. or/-specific factors and different gastroduodenal diseases. The aim of the present study was to clarify the roles of the plasticity region genes [jhp0940, jhp0945, and jhp0947] and the known genes of cagPAI [cagA and cage] in relation to GU and DU diseases

Materials and Methods: A total of 173 strains that were isolated from 114 patients with non-atrophic gastritis [NAG], 30 patients with DU, and 29 patients with GU were genotyped. Data were collected and analyzed using SPSS software version 19.

Results: The cagE gene had the highest frequency [69.4%] and jhp0945 had the least frequency [11.0%] among the genes. When GU was considered as a dependant factor in simple logistic regression analysis, no genotype correlation was found with risk for GU in Iran [p>0.05]. Statistical analysis showed that cagA+ and cagAV jhp0940+ genotypes were significantly associated with an increased risk of DU but not GU. The Odds ratios [95% CI] were 3.143 [1.120-8.817], and 7.250 [1.493-38.199], respectively

Conclusion: Given the high frequency of cagE, this gene could be a suitable marker for the presence of cagPAI in Iranian strains. cagA[+] and cagAV jhp0940+genotypes can be beneficial biomarkers for risk prediction of DU in Iran

Helicobacterpylori and gastric cancer: peptide-based new therapeutic strategies

Helicobacter pylori [H. pylori] is the most important pathogens with the ability to persist for decades in the stomach; and it is considered as the most common agent for gastric cancer

The development of disease depends on factors such as strain-specific bacterial constituents, host susceptibility and environmental cofactors

Eradication of H. pylori can not only remarkably reduce the risk of relapse of peptic ulcers but also decrease the risk of gastric cancer in infected individuals with no severe injury or malignant tumor. In most cases, the gastric MALT lymphoma can be completely treated by the eradication of H. pylori infection

The use of anti-H pylori or anti-cancer therapeutic peptides, may be an effective strategy for the prevention of gastric cancer

Therefore, this review was aimed to assess literature regarding H. pylori virulence factors associated with gastric cancer as well as new therapeutic methods based on peptides

new generation of cold-shock vector derived from pCold I [pCold I-LZ] for expression of recombinant peptides and proteins

Finding shows that there were several problems in the treatment of Helicobacterpylori infection such as the emergence of resistance to the antibiotics, the risk of recrudescence, and the high cost of treatment. The ineffectiveness of conventional treatment mechanisms against cancer cells reveals the importance of peptides as a novel therapeutic approach. However, the short length of peptides was a restriction factor to realise this approach. As a result, one or more amino acid residues were added during the cloning process that leads to the loss of the original peptide folding. The aim of study was to change the structure of the pCold I vector using site-directed mutagenesis in order to do the directional cloning of each target gene and express/purify the small peptides and native proteins without any additional N-terminus amino acids. Site-directed mutagenesis was performed by plasmid amplification in two individual PCR reactions. Two PCR products were mixed and denatured to separate the nascent strands of plasmid DNA from the parental ones. Slow cooling conditions were used to allow reannealing of PCR products. The products were digested with Dpnl that digests methylated parental strands, and then transformed into E.coli DH5a. The mutant plasmid was identified by digestion with Ndel and Peel and sequencing. The mutant plasmids were not digested by Ndel. The presence of mutation was also confirmed by sequencing. In mutant vector the cut sites of both the first restriction enzyme at the multiple cloning site [at the nucleotide level] and factor Xa [at the amino acid level] became the same. The modified vector can be widely used for a fast and more convenient cloning and expression of the native proteins and short peptides, including anti-H.pylori peptides and anti-angiogenesis, gastric anti-CSCs and anti-metastatic peptides

Helicobacterpylori-induced genotoxic damage in human b lymphocytes

Helicobacter pylori [H. pylori] is recognized as the causative agent of peptic and duodenal ulcers, gastric adenocarcinoma, and low-grade mucosa-associated lymphoid tissue [MALT] lymphoma. In the present study, we investigate the genotoxic damage of lysates of H, pylori in human B lymphocytes. Human B lymphocytes were treated with 0, 10, 20, and 30 microg/mL of total protein concentration of lysates obtained from H. pylori isolates from dyspeptic patients. Direct H. pylori-induced DNA damage was investigated by the in vitro cytokinesis-block micronucleus assay which detects chromosomal fragments and maldistributed whole chromosomes. The total mean micronuclei number [tMMN] observed per 1000 binucleus B cells significantly correlated with increasing protein concentration of H pylori lysates [r[2]=0.994, p=0.006]. The highest tMMN [3.81-fold] was observed in cells treated with 30 microg/mL of H, pylori lysate [12.43 +/- 1.91] when compared with the control [3.26 +/- 0.48]. This study provides evidence of the direct effect of H, pylori in chromosomal breakage of human B lymphocytes, which might lead to the development of abnormal B cells. Long-term infection by H. pylori has been implicated in epithelial cell damage as a result of continuous induction of the immune system by bacterial antigens. However, the results of this study propose that persistent H. pylori infection could also directly damage B lymphocyte DNA from which gastric MALT lymphoma arises

Allelic variation of helicobacter pylori baba and caga genes and their association with clinical consequences

Helicobacter pylori [H. pylori] is classified as a class I carcinogen. The low infection rate seen in developed countries [8.9%] compared with a high infection rate [52%-98%] in developing countries indicates a strong association between infection prevalence and socioeconomic status. Adhesion of H, pylori to gastric epithelial cells is an important aggressive factor. One of the genes that encodes for an adhesive protein is babA2, which facilitates the location of bacteria on gastric epithelial cells and delivery of toxic proteins [CagA, VacA] into the host cells. BabA2 is a 78 KD protein that binds to the Le[b] antigens on gastric epithelial cells. Some studies have shown an association between babA2 and peptic ulcer disease or gastric cancer. The cagA gene which encodes an immunodominant protein has a mosaic structure composed of protected and various regions. The C-terminal region of CagA, which includes multiple numbers of EPIYA [Glu-Pro-Ile-Tyr-Ala] motifs, is tyrosine-phosphorylated. Western and East Asian strains represent EPIYA-C and EPIYA-D motifs, respectively. The C- and D- types serve as low-affinity and high-affinity SHP-2-binding sites and interfere with SHP-2 phosphatase activity. A majority of East Asian strains have shown strong conservation and lack of duplication in the D region while the Western strains have shown multiple numbers of the EPIYA-C motif, which increase gastric cancer risk. CagA, either tyrosine-phosphorylated [in its C-terminal motifs] or not in host cells, alters the expression of certain genes to cause gastric cancer. The importance of these genes in predicting clinical outcomes is related to the phylogeographical origins of the bacterium. If the mechanisms by which H. pylori causes cancer are elucidated, they can assist in achieving effective strategies for the prevention and treatment of gastric cancer

Increase in resistance rates of H. pylori isolates to metronidazole and tetracycline-comparison of three 3-year studies

Antimicrobials have been useful in the treatment of H.pylori-related dyspeptic diseases. However, emergence of resistant strains often decreases the eradication rates of H.pylori infections. Large-scale use of antimicrobials will lead to the diminishment of susceptible strains while allowing resistant survivors to outgrow and spread resistance genes. The aim of this study was to assess the change in antimicrobial resistance rate of H.pylori isolates from 2005 to 2008 and indicate the consequences of indiscriminate and widespread use of antimicrobials against H. pylori-and non-H.pylori-related infections. A total of 110 H. pylori strains were isolated from dyspeptic patients during 2005 to 2008 and tested for their susceptibility to antimicrobials using the disk diffusion method. MICs were determined for metronidazole [8 micro g/mL], tetracycline [0.5 micro g/mL], clarithromycin [2 micro g/mL], amoxicillin [1 micro g/mL] and furazolidone [0.5 micro g/mL]. Since the rates of resistance to metronidazole and tetracycline were remarkably high, another 50 isolates were tested for their susceptibility to metronidazole at the same MIC [8 micro g/mL] and tetracycline at MICs of 0.5, 1 and 2 micro g/mL. Resistance rates were compared to those obtained in our two previous studies between 1997-2000 and 2001-2004. The resistance rates of 110 H.pylori isolates to clarithromycin, amoxicillin and furazolidone were 7.3%, 7.3%, and 4.5%, respectively. Among 160 H.pylori isolates, 55.6% exhibited resistance to metronidazole and 38.1% to tetracycline. Compared to our two previous studies, the resistance rates of H.pylori isolates to current antimicrobials has changed over time. The change in resistance rates of clarithromycin, amoxicillin and furazolidone was not statistically significant. However, resistance to metronidazole and tetracycline showed a considerable increase from 33-36.3% to 55.6% and 0-0.7% to 38.1%, respectively. Emergence of resistance due to the intensive use of antibiotics has become a global public health problem. It appears that plasmid-carried genes are involved in the spread of resistance traits among bacteria. Results obtained in this study indicate that the increase in resistance rates of H.pylori isolates to metronidazole and tetracycline could be the indication of indiscriminate and frequent use of antibiotics in Iran