Increased oxidative DNA damage, inducible nitric oxide synthase, nuclear factor κB expression and enhanced antiapoptosis-related proteins in Helicobacter pylori-infected non-cardiac gastric adenocarcinoma

BIRC3 induces the phosphoinositide 3-kinase-Akt pathway activation to promote trastuzumab resistance in human epidermal growth factor receptor 2-positive gastric cancer

BACKGROUND

Trastuzumab-targeted therapy is currently the standard of care for advanced human epidermal growth factor receptor 2 (HER2)-positive gastric cancer. However, the emergence of resistance to trastuzumab poses significant challenges.

AIM

To identify the key genes associated with trastuzumab resistance. These results provide a basis for the development of interventions to address drug resistance and improve patient outcomes.

METHODS

High-throughput sequencing and bioinformatics were used to identify the differentially expressed pivotal gene BIRC3 and delineate its potential function and pathway regulation. Tumor samples were collected from patients with HER2-positive gastric cancer to evaluate the correlation between BIRC3 expression and trastuzumab resistance. We established gastric cancer cell lines with both highly expressed and suppressed levels of BIRC3, followed by comprehensive in vitro and in vivo experiments to confirm the involvement of BIRC3 in trastuzumab resistance and to elucidate its underlying mechanisms.

RESULTS

In patients with HER2-positive gastric cancer, there is a significant correlation between elevated BIRC3 expression in tumor tissues and higher T stage, tumor node metastasis stage, as well as poor overall survival and progression-free survival. BIRC3 is highly expressed in trastuzumab-resistant gastric cancer cell lines, where it inhibits tumor cell apoptosis and enhances trastuzumab resistance by promoting the phosphorylation and activation of the phosphoinositide 3-kinase-Akt (PI3K-AKT) pathway in HER2-positive gastric cancer cells, both in vivo and in vitro.

CONCLUSION

This study revealed a robust association between high BIRC3 expression and an unfavorable prognosis in patients with HER2-positive gastric cancer. Thus, the high expression of BIRC3 stimulated PI3K-AKT phosphorylation and activation, stimulating the proliferation of HER2-positive tumor cells and suppressing apoptosis, ultimately leading to trastuzumab resistance.

The role of nitric oxide synthase/ nitric oxide in infection-related cancers: Beyond antimicrobial activity

As a free radical and endogenous effector molecule, mammalian endogenous nitric oxide (NO) is mainly derived from nitric oxide synthase (NOS) via L-arginine. NO participates in normal physiological reactions and provides immune responses to prevent the invasion of foreign bacteria. However, NO also has complex and contradictory biological effects. Abnormal NO signaling is involved in the progression of many diseases, such as cancer. In the past decades, cancer research has been closely linked with NOS/ NO, and many tumors with poor prognosis are associated with high expression of NOS. In this review, we give a overview of the biological effects of NOS/ NO. Then we focus on the oncogenic role of iNOS/ NO in HPV, HBV, EBV and H. pylori related tumors. In fact, there is growing evidence that iNOS could be used as a potential therapeutic target in cancer therapy. We emphasize that the pro-tumor effect of NOS/ NO is greater than the anti-tumor effect.

NF-κB in Gastric Cancer Development and Therapy

Gastric cancer is considered one of the most common causes of cancer-related death worldwide and, thus, a major health problem. A variety of environmental factors including physical and chemical noxae, as well as pathogen infections could contribute to the development of gastric cancer. The transcription factor nuclear factor kappa B (NF-κB) and its dysregulation has a major impact on gastric carcinogenesis due to the regulation of cytokines/chemokines, growth factors, anti-apoptotic factors, cell cycle regulators, and metalloproteinases. Changes in NF-κB signaling are directed by genetic alterations in the transcription factors themselves, but also in NF-κB signaling molecules. NF-κB actively participates in the crosstalk of the cells in the tumor micromilieu with divergent effects on the heterogeneous tumor cell and immune cell populations. Thus, the benefits/consequences of therapeutic targeting of NF-κB have to be carefully evaluated. In this review, we address recent knowledge about the mechanisms and consequences of NF-κB dysregulation in gastric cancer development and therapy.

Manifold role of ubiquitin in Helicobacter pylori infection and gastric cancer

Infection with H. pylori induces a strong host cellular response represented by induction of a set of molecular signaling pathways, expression of proinflammatory cytokines and changes in proliferation. Chronic infection and inflammation accompanied by secretory dysfunction can result in the development of gastric metaplasia and gastric cancer. Currently, it has been determined that the regulation of many cellular processes involves ubiquitinylation of molecular effectors. The binding of ubiquitin allows the substrate to undergo a change in function, to interact within multimolecular signaling complexes and/or to be degraded. Dysregulation of the ubiquitinylation machinery contributes to several pathologies, including cancer. It is not understood in detail how H. pylori impacts the ubiquitinylation of host substrate proteins. The aim of this review is to summarize the existing literature in this field, with an emphasis on the role of E3 ubiquitin ligases in host cell homeodynamics, gastric pathophysiology and gastric cancer.

Tampering of Viruses and Bacteria with Host DNA Repair: Implications for Cellular Transformation

A reduced ability to properly repair DNA is linked to a variety of human diseases, which in almost all cases is associated with an increased probability of the development of cellular transformation and cancer. DNA damage, that ultimately can lead to mutations and genomic instability, is due to many factors, such as oxidative stress, metabolic disorders, viral and microbial pathogens, excess cellular proliferation and chemical factors. In this review, we examine the evidence connecting DNA damage and the mechanisms that viruses and bacteria have evolved to hamper the pathways dedicated to maintaining the integrity of genetic information, thus affecting the ability of their hosts to repair the damage(s). Uncovering new links between these important aspects of cancer biology might lead to the development of new targeted therapies in DNA-repair deficient cancers and improving the efficacy of existing therapies. Here we provide a comprehensive summary detailing the major mechanisms that viruses and bacteria associated with cancer employ to interfere with mechanisms of DNA repair. Comparing these mechanisms could ultimately help provide a common framework to better understand how certain microorganisms are involved in cellular transformation.

H. pylori infection confers resistance to apoptosis via Brd4-dependent BIRC3 eRNA synthesis

H. pylori infection is one of the leading causes of gastric cancer and the pathogenicity of H. pylori infection is associated with its ability to induce chronic inflammation and apoptosis resistance. While H. pylori infection-induced expression of pro-inflammatory cytokines for chronic inflammation is well studied, the molecular mechanism underlying the apoptosis resistance in infected cells is not well understood. In this study, we demonstrated that H. pylori infection-induced apoptosis resistance in gastric epithelial cells triggered by Raptinal, a drug that directly activates caspase-3. This resistance resulted from the induction of cIAP2 (encoded by BIRC3) since depletion of BIRC3 by siRNA or inhibition of cIAP2 via BV6 reversed H. pylori-suppressed caspase-3 activation. The induction of cIAP2 was regulated by H. pylori-induced BIRC3 eRNA synthesis. Depletion of BIRC3 eRNA decreased H. pylori-induced cIAP2 and reversed H. pylori-suppressed caspase-3 activation. Mechanistically, H. pylori stimulated the recruitment of bromodomain-containing factor Brd4 to the enhancer of BIRC3 and promoted BIRC3 eRNA and mRNA synthesis. Inhibition of Brd4 diminished the expression of BIRC3 eRNA and the anti-apoptotic response to H. pylori infection. Importantly, H. pylori isogenic cagA-deficient mutant failed to activate the synthesis of BIRC3 eRNA and the associated apoptosis resistance. Finally, in primary human gastric epithelial cells, H. pylori also induced resistance to Raptinal-triggered caspase-3 activation by activating the Brd4-dependent BIRC3 eRNA synthesis in a CagA-dependent manner. These results identify a novel function of Brd4 in H. pylori-mediated apoptosis resistance via activating BIRC3 eRNA synthesis, suggesting that Brd4 could be a potential therapeutic target for H. pylori-induced gastric cancer.

H9N2 swine influenza virus infection-induced damage is mediated by TRPM2 channels in mouse pulmonary microvascular endothelial cells

Oxidative stress is implicated in the pathogenesis of influenza virus infection. Increasing evidences show that transient receptor potential melastatin 2 (TRPM2), a Ca²⁺-permeable non-selective cation channel, plays an important role in the pathomechanism of reactive oxygen species (ROS)-coupled diseases. The present study investigated the role of TRPM2 in pulmonary microvascular endothelial cells (PMVECs) during H9N2 influenza virus infection. We knocked down TRPM2 in PMVECs using TRPM2 shRNA lentiviral particles. Subsequently, we utilized enzyme-linked immunosorbent assay and flow cytometry to compare ROS levels, DNA damage, mitochondrial integrity, apoptosis, and inflammatory factors between control and TRPM2-knockdown PMVECs following H9N2 influenza virus infection. Inhibition of TRPM2 channels reduced H9N2 virus-induced intracellular ROS production, decreased DNA damage, and inhibited H9N2-induced cellular apoptosis. This study shows that the inhibition of TRPM2 channels may protect PMVECs from the damage caused by H9N2 virus infection. Our results highlight the importance of TRPM2 in modulating ROS production, apoptosis, mitochondrial dysfunction, cytokine expression, and DNA damage in H9N2 virus-infected PMVECs, and suggest that TRPM2 may be a potential antiviral target.

A lucid review of Helicobacter pylori-induced DNA damage in gastric cancer

Helicobacter pylori (H pylori) is the main risk factor for gastric cancer (GC). In recent years, many studies have addressed the effects of H pylori itself and of H pylori-induced chronic inflammation on DNA damage. Unrepaired or inappropriately repaired DNA damage is one possible carcinogenic mechanism. We may conclude that H pylori-induced DNA damage is one of the carcinogenic mechanisms of GC. In this review, we summarize the interactions between H pylori and DNA damage and the effects of H pylori-induced DNA damage on GC. Then, focusing on oxidative stress, we introduce the application of antioxidants in GC. At the end of this review, we discuss the outlook for further research on H pylori-induced DNA damage.

Gene expression patterns of COX-1, COX-2 and iNOS in H. Pylori infected histopathological conditions

BACKGROUND

Research indicates that Helicobacter pylori can inflict severe histological damage through the modulation of host-related genes. The current study investigated the effect of H. pylori genotypes in the outcome of disease, and the expression of anti-apoptotic related genes, COX-1, COX-2, and iNOS genes in benign, pre-malignant, and malignant lesions of gastric carcinogenesis.

MATERIALS AND METHODS

Tissue samples from H. pylori positive patients were graded based on the genotype of the infected H. pylori strain. Expression of COX-1, COX-2 and iNOS was assessed using a combination of real-time PCR and immunohistochemistry.

RESULTS

Gene expression studies confirmed that COX-2 and iNOS expression was highly and selectively induced in epithelium with premalignant changes such as atrophic conditions, metaplasia and dysplasia, suggesting an important role of these genes in the sequence to gastric carcinoma of the intestinal type. Furthermore, the expression of COX-2 and iNOS was also dependent on the genotype of H. pylori and subjects with genotype-1 exhibited significantly higher expressions of COX-2 and iNOS compared to other genotypes. Comparison of the expression levels among infected and uninfected individuals demonstrated significant difference in the expression pattern of COX-2 gene whereas iNOS expression was found only in subjects infected H. pylori (p < 0.001). Immunohistochemical staining showed 1.5619 folds higher propensity of COX-2 and 3.2941 folds higher intensity of iNOS expression in subjects infected with H. pylori genotype 1.

CONCLUSION

The up-regulation of COX-2 and iNOS was associated with the genotype of the H. pylori strain and the presence of certain genotype may greatly affect early events during carcinogenesis.

Analytical methods to access the chemical composition of an Euphorbia tirucalli anticancer latex from traditional Brazilian medicine

ETHNOPHARMACOLOGICAL RELEVANCE

Euphorbia tirucalli L. is widely used by Brazilian folk medicine, mainly for its anticancer activity. However, its commercialization was banned by The Brazilian National Sanitary Surveillance Agency (ANVISA) due to the presence of some compounds considered toxic, such as the diterpene esters.

AIM OF THE STUDY

Chemical and biological analyses were performed with the Brazilian Euphorbia tirucalli latex to support its wide traditional use in Brazil.

MATERIAL AND METHODS

Latex was collected by using two procedures, in a solution of dichloromethane: methanol (3:1, 100 mL) and in 100 mL of distilled water. The first procedure was concentrated as a crude extract and the second one was partitioned with hexane and dichloromethane. The partitions and crude extract were subjected to phytochemical analyses using three different methods: Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS) with electrospray ionization sources in negative mode (ESI(-)) as well as in tandem mass spectrometry ESI(-) MS/MS and Atmospheric Pressure Chemical Ionization in positive mode (APCI(+)), Gas Chromatography coupled Mass Spectrometry (GC-MS) and Nuclear Magnetic Resonance (NMR) (¹H-NMR and ¹³C-NMR). The cytotoxic potential was evaluated using the crude extract in macrophages RAW 264.7 and Gastric Adenocarcinoma (AGS) cancer cells. The evaluation of immunomodulatory activity was made through the detection of Nitric Oxide (NO) and cytokines as Tumor necrosis factor α (TNF-α) and Interleukin-6 (IL-6).

RESULTS

GC-MS showed the presence of some esters of fatty acids, for instance myristic, palmitic, stearic, oleic and linoleic acid and, mainly, triterpenes such as euphol and tirucallol. With NMR, most of the signals were related to triterpenoids euphol and tirucallol. However, when the latex was analyzed with ESI(-) FT-ICR MS, a wide variety of molecules from different classes of natural products (fatty acids, diterpenes, triterpenes, steroids) were found. On the other hand, when APCI(+)FT-ICR MS was used, the ion M^+. At ratio mass-charge (m/z) 426.38567, related to triterpenes euphol and tirucallol masses, presented the most intense peak, with a mass error of -0.11, indicating high accuracy. Diterpene esters from 4-deoxyphorbol and ingenol were identified only by ESI(-)FT-ICR MS and ESI(-)FT-ICR MS/MS. When evaluated biologically, the crude latex showed immunomodulatory activity, as it reduced the production of the pro-inflammatory cytokines TNF-α, IL-6 and NO, and the effect on NO reduction was more significant, obtaining in a similar result to the N(ω)-Nitro-L-Arginine Methyl Ester (L-NAME) standards, as well as significant cytotoxic activity with half inhibitory concentration (IC₅₀) values of 69.43 ± 1.29 μg/mL against AGS without damaging healthy ones.

CONCLUSION

It was verified that the Brazilian Euphorbia tirucalli latex consists mainly of the triterpenes euphol and tirucallol, which may be the main cause of the anticancer activity attributed to the plant, but many other minor compounds could have been determined by the FT-ICR MS method, such as the diterpene esters. It has antitumor potential because it acts selectively against cancer cells and it also prevents the progression of tumors, because it carries an important immunomodulatory effect.

The genetic association between iNOS and eNOS polymorphisms and gastric cancer risk: a meta-analysis

Objective

There are a number of susceptible factors for an increased risk of gastric cancer. Nitric oxide (NO) is considered to be associated with the development of a range of cancers. In particular, inducible nitric oxide synthase (iNOS) and endothelial nitric oxide synthase (eNOS) are known to play a central role in the production of NO. Published studies relating to the association between eNOS rs1799983, rs2070744, and iNOS rs2297518 polymorphisms and the risk of gastric cancer risk are conflicting and inconclusive and require further analysis.

Materials and methods

This study involved a meta-analysis of case–control studies relating to eNOS rs1799983, rs2070744, and iNOS rs2297518 polymorphisms published prior to January 2018. Literature searches were carried out in PubMed, Embase, Web of Science, the Cochrane Library databases, and the Chinese National Knowledge Infrastructure. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were used to evaluate the strength of association based on genotype data.

Results

A total of 1,356 cases and 1,791 controls were included from nine case–control studies involving eNOS rs1799983 (G894T), rs2070744 (T-786C), and iNOS rs2297518 (C150T) polymorphisms. Data analysis indicated that iNOS rs2297518 was a risk factor for Helicobacter pylorus-positive gastric cancer when compared with H. pylorus-negative gastric cancer (p=0.003, OR [95% CI] =2.19 [1.31–3.66]). In addition, the allelic, dominant, and recessive models of eNOS rs2070744 were significantly associated with a risk of gastric cancer (allelic model: p<0.00001, OR [95% CI] =0.23 [0.16–0.34]; dominant model: p<0.00001, OR [95% CI] =0.25 [0.15–0.42]; recessive model: p<0.00001, OR [95% CI] =0.16 [0.08–0.30]). No association was identified between eNOS rs1799983 and the risk of gastric cancer (p>0.05).

Conclusion

iNOS rs2297518 and eNOS rs2070744 polymorphisms may represent susceptible factors for gastric cancer.

Helicobacter pylori Eradication Downregulates Cellular Inhibitor of Apoptosis Protein 2 in Gastric Carcinogenesis

Background/Aims

To evaluate the expression of cellular inhibitor of apoptosis protein 2 (cIAP2) during gastric carcinogenesis after Helicobacter pylori (HP) infection and after HP eradication.

Methods

We divided non-cancer patients into four groups according to the status of HP infection and atrophic gastritis (AG)/intestinal metaplasia (IM). We compared cIAP2 mRNA expression among these four groups and patients with HP-positive early gastric cancer (EGC) by using real-time polymerase chain reaction (PCR). We evaluated the expression of cIAP2 messenger RNA (mRNA)/protein by using real-time PCR/immunohistochemistry and the degree of apoptosis with a terminal deoxynucleotidyl transferase-mediated nick end labeling assay before and 12 months after endoscopic submucosal dissection (ESD) in HP-positive EGC patients, regardless of whether they had undergone eradication therapy.

Results

The expression of cIAP2 mRNA was significantly higher in the groups with HP(+), AG/IM(+), and HP-positive EGC than in the control, HP(+), and AG/IM(−) groups (p<0.005). In the HP eradication group, the expression of cIAP2 mRNA/protein significantly decreased (p=0.006) and apoptosis increased at the 12-month follow-up after ESD. In the HP noneradication group, the aforementioned changes were not found during the same follow-up period.

Conclusions

The expression of cIAP2 increased during gastric carcinogenesis after HP infection; HP eradication in the patients who had undergone ESD for EGC reversed overexpression of cIAP2 and suppressed cell apoptosis.

Inducible Nitric Oxide Synthase in the Carcinogenesis of Gastrointestinal Cancers

SIGNIFICANCE

Gastrointestinal (GI) cancer taken together constitutes one of the most common cancers worldwide with a broad range of etiological mechanisms. In this review, we have examined the impact of nitric oxide (NO) on the etiology of colon, colorectal, gastric, esophageal, and liver cancers. Recent Advances: Despite differences in etiology, initiation, and progression, chronic inflammation has been shown to be a common element within these cancers showing interactions of numerous pathways. NO generated at the inflammatory site contributes to the initiation and progression of disease. The amount of NO generated, time, and site vary and are an important determinant of the biological effects initiated. Among the nitric oxide synthase enzymes, the inducible isoform has the most diverse range, participating in numerous carcinogenic processes. There is emerging evidence showing that inducible nitric oxide synthase (NOS2) plays a central role in the process of tumor initiation and/or development.

CRITICAL ISSUES

Redox inflammation through NOS2 and cyclooxygenase-2 participates in driving the mechanisms of initiation and progression in GI cancers.

FUTURE DIRECTIONS

Understanding the underlying mechanism involved in NOS2 activation can provide new insights into important prevention and treatment strategies. Antioxid. Redox Signal. 26, 1059-1077.

Relation between gastric cancer and protein oxidation, DNA damage, and lipid peroxidation

OBJECTS

The aim of this study is to evaluate protein oxidation, DNA damage, and lipid peroxidation in patients with gastric cancer and to investigate the relationship between oxidative stress and gastric cancer.

METHODS

We investigated changes in serum protein carbonyl (PC), advanced oxidation protein products (AOPP), and 3-nitrotyrosine (3-NT) levels, as indicators of protein oxidation, serum 8-hydroxydeoxyguanosine (8-OHdG), as a biomarker of DNA damage, and malondialdehyde (MDA), conjugated diene (CD), 4-hydroxynonenal (4-HNE), and 8-ISO-prostaglandin F2α (8-PGF) in serum, as lipid peroxidation markers in gastric cancer (GC) patients and healthy control.

RESULTS

Compared with control, a statistically significant higher values of 8-OHdG, PC, AOPP, and 3-NT were observed in the GC patients (P < 0.05). The products of lipid peroxidation, MDA, CD, 4-HNE, and 8-PGF, were significantly lower in the GC patients compared to those of control (P < 0.05). In addition, the products of oxidative stress were similar between the Helicobacter pylori positive and the negative subgroups of GC patients.

CONCLUSIONS

GC patients were characterized by increased protein oxidation and DNA damage, and decreased lipid peroxidation. Assessment of oxidative stress and augmentation of the antioxidant defense system may be important for the treatment and prevention of gastric carcinogenesis.

Gastric adenocarcinoma and Helicobacter pylori: correlation with p53 mutation and p27 immunoexpression

INTRODUCTION

Helicobacter pylori infection is an established risk factor for gastric cancer development, but the exact underlying mechanism still remains obscure. The inactivation of tumor suppressor genes such as p53 and p27(KIP1) is a hypothesized mechanism, although there is no consensus regarding the influence of H. pylori cagA(+) in the development of these genetic alterations.

GOALS

To verify the relationship among H. pylori infection, p53 mutations and p27(Kip1) Protein (p27) expression in gastric adenocarcinomas (GA) seventy-four tissues were assayed by PCR for H. pylori and cagA presence. Mutational analysis of p53 gene was performed by single-strand conformation polymorphism (SSCP). Seventy tissues were analyzed by an immunohistochemical method for p27 expression.

RESULTS

From the samples examined, 95% (70/74) were H. pylori positive, 63% cagA(+). Altered p53 electrophoretic mobility was found in 72% of cases and significantly more frequent in the presence of cagA. Considerable reduction in p27 expression (19%) was found with a tendency for association between cagA(+) and p27(-), although the results were not statistically significant. Concomitant alterations of both suppressor genes were detected in 60% of cases. In the cases cagA(+), 66.7% of them had these concomitant alterations.

CONCLUSIONS

The data suggest that H. pylori cagA(+) contributes to p53 alteration and indicate that concomitant gene inactivation, with reduced p27 expression, may be a mechanism in which H. pylori can promote the development and progression of gastric cancer.

Correlation of xenobiotic-metabolizing enzymes, oxidative stress and NFkappaB signaling with histological grade and menopausal status in patients with adenocarcinoma of the breast

BACKGROUND

Adenocarcinoma of the breast is the most common cancer worldwide and accounts for the highest morbidity and mortality. The increasing global incidence of breast cancer emphasizes the need to understand the molecular mechanisms of breast tumorigenesis. The present study was designed to correlate changes in xenobiotic-metabolizing enzymes (XME), oxidative stress and NFkappaB signaling with histological grading and menopausal status in breast cancer patients.

METHOD

Sixty breast cancer patients histologically categorized as grades I, II and III, and as pre- and postmenopausal were chosen for the study. We analyzed phase I and phase II XME activities as well as the expression of the CYP isoforms CYP1A1 and CYP1B1, oxidative stress markers, and the expression of NFkappaB family members in tumor and adjacent tissues by immunohistochemical localization and Western blot analyses.

RESULTS

The breast tumors analyzed in the present study were characterized by increased activities of xenobiotic-metabolizing enzymes and enhanced oxidative damage to lipids, proteins, and DNA associated with variations in the expression of NFkappaB family members. The magnitude of the changes was however more pronounced in premenopausal patients and in grade III breast tumors.

CONCLUSION

The present study delineates the correlation between XME-mediated oxidative stress and NFkappaB signaling that leads to the development of breast cancer.

Antimicrobial activity of Artemisia douglasiana and dehydroleucodine against Helicobacter pylori

ETHNOPHARMACOLOGICAL RELEVANCE

The increasing resistance of Helicobacter pylori to antibiotics demands the search for novel compounds from plant based sources. Artemisia douglasiana Besser is widely used in Cuyo region (Argentina) as folk medicine for the treatment of gastric ailments.

AIM OF STUDY

Based on our previous studies that Artemisia douglasiana exert cytoprotective actions against ethanol-induced gastric mucosal injury we assayed the anti-Helicobacter pylori effect of the Artemisia douglasiana extract and its active compound, dehydroleucodine.

MATERIALS AND METHODS

The in vitro anti-bacterial activity of Artemisia douglasiana extract and its active compound, dehydroleucodine were determined against one standard strain and six clinical isolates of Helicobacter pylori by using the agar dilution methods.

RESULTS

The results showed that both dehydroleucodine and Artemisia douglasiana extract had activity against the microorganism with MICs between 1-8 and 60-120 mg/L, respectively.

CONCLUSIONS

Artemisia douglasiana may be a useful alternative treatment strategy principally in eradication of metronidazole and clarithromycin-resistant strain.

Endothelial nitric oxide synthase (eNOS) is not upregulated in gastric mucosa of Helicobacter pylori (H. pylori)-positive patients with type 2 diabetes mellitus

AIM

To evaluate the expression of eNOS and CD34 in gastric mucosa of Helicobacter pylori (H. pylori) positive diabetic patients, in correlation with glycaemic control and diabetic autonomic neuropathy (DAN).

METHODS

We prospectively studied 49 diabetic type 2 patients (29 women, mean age 65.32+/-8.56 years) and 30 control subjects (15 women, mean age 58.47+/-12.40) that underwent endoscopy. Biopsies from the body and antrum were evaluated for H. pylori-gastritis, eNOS and angiogenic marker CD34 expression. Statistical analysis in correlation with mean glycosylated haemoglobin (HbA1c) of the last 3 years, and DAN was performed.

RESULTS

The two groups were matched for age (p=0.144), sex (p=0.335), H. pylori-infection (p=0.617) and degree of gastritis (p=0.78). eNOS and CD34 attenuated expression correlated with diabetes mellitus (DM) in the corpus (p=0.009 and 0.02, respectively). eNOS and CD34 expression was upregulated in H. pylori-positive controls but not in H. pylori-positive diabetic patients (p=0.010 and 0.007 for the corpus and p=0.036 and 0.047 for the antrum, respectively). eNOS expression correlated with good glycaemic control (GGC) in the gastric corpus (p<0.001) and antrum (p=0.0037) and with absence of DAN (p=0.009 and 0.036, respectively for the corpus and antrum).

CONCLUSION

Chronic glycaemic control affects eNOS expression and angiogenesis in the gastric mucosa of patients with type 2 DM. eNOS expression is not upregulated in H. pylori-positive diabetic patients.

Helicobacter pylori infection and the pathogenesis of gastric cancer: a paradigm for host-bacterial interactions

Helicobacter pylori infection is the most important acquired risk factor for gastric cancer. The infection initiates a chronic inflammatory process that eventually alters the physiology of the gastric environment and leads to achlorohydria. Gastric atrophy may be part of this process but cancer can arise without this precursor. The net effect of decades of inflammation is the establishment of a milieu awash with pro-inflammatory cytokines and characterized by the activation of signalling pathways that cross-talk between inflammation and carcinogenesis. Many of the factors involved in chronic inflammation play a dual role in the process-promoting neoplastic progression but also facilitating cancer prevention. H. pylori bacterial virulence factors as well as host genetic factors play a major role in orchestrating the increased risk of cancer. The study of such host-bacterial interaction is key to uncovering the molecular and cellular pathways involved and will ultimately lead to developing preventive and therapeutic strategies against this global killer.

Effects of different Helicobacter pylori culture filtrates on growth of gastric epithelial cells

AIM

To study the effects of different Helicobacter pylori (H pylori) culture filtrates on growth of gastric epithelial cells.

METHODS

Broth culture filtrates of H pylori were prepared. Gastric epithelial cells were treated with the filtrates, and cell growth was determined by growth curve and flow cytometry. DNA damage of gastric epithelial cells was measured by single-cell microgel electrophoresis.

RESULTS

Gastric epithelial cells proliferated actively when treated by CagA-gene-positive broth culture filtrates, and colony formation reached 40%. The number of cells in S phase increased compared to controls. Comet assay showed 41.2% comet cells in GES-1 cells treated with CagA-positive filtrates (P < 0.05).

CONCLUSION

CagA-positive filtrates enhance the changes in morphology and growth characteristics of human gastric epithelial tumor cells. DNA damage maybe one of the mechanisms involved in the growth changes.

New Aspects of Helicobacter pylori Infection Involvement in Gastric Oncogenesis

Gastric adenocarcinoma not located in the cardia still remains second only to lung cancer as the leading cause of cancer-related mortality worldwide, whereas adenocarcinoma of the cardia and gastroesophageal junction has been rapidly rising over the past two decades. Gastric malignancy can be subdivided into diffuse and intestinal pathologic entities that have different epidemiological and prognostic features. Various genetic and environmental factors lead to either abnormal gene overexpression or inappropriate expression of normal genes, whose products confer the malignant phenotype. Advances have been made in genetic changes mostly of the intestinal type; its development is probably a multistep process, as has been well described in colon carcinogenesis. Oncogene overexpression, tumor suppressor loss, and defective DNA mismatch repair is associated with gastric cancer. The most common genetic abnormalities tend to be loss of heterozygosity of particularly tumor suppressor p53 gene or "adenomatous polyposis coli" gene. The latter leads to gastric carcinogenesis through changes related to E-cadherin-catenin complex, which plays a critical role in normal tissue architecture maintenance. Mutation of any of its components results in loss of cell-cell adhesion, thereby contributing to malignancy. Putative trophic factors have also been involved in gastric oncogenesis. E-cadherin/CDH1 gene germline mutations have been recognized in families with an inherited predisposition to diffuse-type malignancy. This review focuses mainly on Helicobacter pylori infection involved in gastric carcinogenesis through various mechanisms, including repopulation of the stomach with bone marrow-derived stem cells that may facilitate gastric cancer progression, thereby necessitating eradication of this bacterium.

Difference of p53AIP1 mRNA expression in gastric mucosa between patients with gastric cancer and chronic gastritis infected with Helicobacter pylori

GOALS

To examine the significance of alteration of p53-regulated apoptosis-induced protein 1 (p53AIP1) expression in gastric carcinogenesis in patients with Helicobacter pylori infection.

BACKGROUND

H. pylori infection induces gastric mucosal inflammation and DNA damage of epithelial cells, which associate with gastric carcinogenesis. p53AIP1 is expressed after DNA damage and induces apoptosis in human cell lines.

STUDY

Endoscopic antral and corpus biopsies were obtained from 13 patients with chronic gastritis and 17 with gastric cancer. Expression of p53AIP1 and p53DINP1 mRNA was examined by semiquantitative reverse transcription polymerase chain reaction and mutation of p53 codon-46 was studied by direct sequence analysis. The grade of gastritis was assessed according to the updated Sydney System. Results were compared between patients with gastric cancer and chronic gastritis.

RESULTS

In the antrum, p53AIP1 mRNA expression was significantly lower in patients with gastric cancer than in those with chronic gastritis (P<0.05). In patients with chronic gastritis, expression of p53AIP1 mRNA was significantly higher in the antrum than in the corpus (P<0.05). In patients with chronic gastritis, antral mucosa with high p53AIP1 expression tended to have severe intestinal metaplasia. No mutation was found at p53 codon-46.

CONCLUSIONS

In H. pylori-infected gastric mucosa expression of p53AIP1 would be higher when the inflammation is severe or intestinal metaplasia is present. Insufficient expression of p53AIP1 may play a role in gastric carcinogenesis in patients infected with H. pylori infection.

The effect of nitric oxide, growth factors, and estrogen on gastric cell migration

BACKGROUND

To study gastric epithelial cell migration during nitric oxide (NO) and growth factor treatment, simulating inflammation and infection. Also, the effects of estrogen on migration of different malignant and nonmalignant gastric epithelial cell lines were explored.

MATERIAL AND METHODS

Isolated primary cultured rabbit gastric epithelial cells, rat gastric mucosal cells, human gastric adenocarcinoma cells, and human colon adenocarcinoma cells (WiDr) were cultured to confluency in appropriate media (5% CO2, 37 degrees C). The cells were treated by hepatocyte growth factor (HGF), transforming growth factor-alpha (TGF-alpha) and keratinocyte growth factor (KGF), with and without sodium nitroprusside (SNP, NO donor) or 17beta-estradiol. Caspase-3 activity and cell viability and migration speed after wounding were measured.

RESULTS

HGF was the most potent growth factor to stimulate migration. SNP dose-dependently decreased the speed of migration. HGF and TGF-alpha were able to overcome the SNP-induced inhibition of migration, whereas KGF was not. SNP also induced caspase-3 activity, which was inhibited by HGF and TGF-alpha. 17beta-estradiol decreased migration in all epithelial cells, but the decrease was more profound in malignant cell lines. HGF could overcome the estrogen retarded migration.

CONCLUSIONS

Growth factors can overcome NO-induced retardation of cell migration and inhibit NO-induced caspase-3 activity, which altogether might also have physiological significance in in vivo inflammation and in gastric cancer. The more profound decrease in migration speed of gastric adenocarcinoma cell line may suggest that estrogen might be one of the protective factor against female gastric adenocarcinoma before menopausal age.

A paradigm for direct stress-induced mutation in prokaryotes

Environmental stresses may lead to selection for hypermutator bacterial cells, which have an increased chance of generating beneficial variants. With stress removal, cost of mutation exceeds the fitness advantage, selecting against hypermutators. Hypermutators arise through several mechanisms, including inactivation of mismatch repair genes (MMR) or induction of error-prone polymerases. Helicobacter pylori may provide an alternative mechanism of stress-induced mutagenesis, since it lacks the MMR genes and error-prone polymerases found in other bacterial species, and possesses an endogenously high mutation frequency. In this study, we expose H. pylori strains to reactive oxygen species and reactive nitrogen species, stressors found in their natural environment. These exposures directly resulted in elevated rates of spontaneous point mutation, deletion between direct repeats, and intergenomic recombination. We demonstrate that these effects are transient and do not involve selection for hypermutator strains. That H. pylori possesses direct repeats in regions where potential gene rearrangements can occur suggests a mechanism for targeted mutation in response to stress that avoids the deleterious fitness costs of fixed hypermutation. These studies provide a new paradigm for adaptation under increased selective pressures that may be present in other prokaryotes.

Nitric oxide, a double edged sword in cancer biology: Searching for therapeutic opportunities

Nitric oxide (NO) is a pleiotropic molecule critical to a number of physiological and pathological processes. The last decade has witnessed major advances in dissecting NO biology and its role in cancer pathogenesis. However, the complexity of the interactions between different levels of NO and several aspects of tumor development/progression has led to apparently conflicting findings. Furthermore, both anti-NO and NO-based anticancer strategies appear effective in several preclinical models. This paradoxical dichotomy is leaving investigators with a double challenge: to determine the net impact of NO on cancer behavior and to define the therapeutic role of NO-centered anticancer strategies. Only a comprehensive and dynamic view of the cascade of molecular and cellular events underlying tumor biology and affected by NO will allow investigators to exploit the potential antitumor properties of drugs interfering with NO metabolism. Available data suggest that NO should be considered neither a universal target nor a magic bullet, but rather a signal transducer to be modulated according to the molecular makeup of each individual cancer and the interplay with conventional antineoplastic agents.

Alzheimer's disease and Helicobacter pylori infection: Defective immune regulation and apoptosis as proposed common links

Although degenerative diseases of the central nervous system, including Alzheimer's disease (AD), have an increasingly high impact on aged population their association with Helicobacter pylori (H. pylori) infection has not as yet been thoroughly researched. Current H. pylori infection appears to induce irregular humoral and cellular immune responses that, owing to the sharing of homologous epitopes (molecular mimicry), cross-react with components of nerves, thereby contributing and possibly perpetuating the apoptotic neural tissue damage observed in neurodegenerative diseases including AD. An association between AD and H. pylori infection has been recently addressed by two studies. A higher seropositivity for anti-H. pylori immunoglobulin G antibodies in 30 patients with AD than in 30 age-matched controls was reported in one study; this serological test, however, has limitations because it does not discriminate between current and old infections. In the other study, by introducing the histological method (the actual gold standard) for diagnosis of H. pylori infection, we reported a higher prevalence of H. pylori infection in 50 AD patients than in 30 anemic controls. This pathogen may influence the pathophysiology of AD by promoting platelet and platelet-leukocyte aggregation; releasing various pro-inflammatory and vasoactive substances; developing cross-mimicry with host antigens; producing reactive oxygen metabolites and circulating lipid peroxides; influencing the apoptotic process; and increasing, through induction of atrophic gastritis, homocysteine, which contributes to vascular disorders implicated in endothelial damage and neurodegeneration.

UvrD helicase suppresses recombination and DNA damage-induced deletions

UvrD, a highly conserved helicase involved in mismatch repair, nucleotide excision repair (NER), and recombinational repair, plays a critical role in maintaining genomic stability and facilitating DNA lesion repair in many prokaryotic species. In this report, we focus on the UvrD homolog in Helicobacter pylori, a genetically diverse organism that lacks many known DNA repair proteins, including those involved in mismatch repair and recombinational repair, and that is noted for high levels of inter- and intragenomic recombination and mutation. H. pylori contains numerous DNA repeats in its compact genome and inhabits an environment rich in DNA-damaging agents that can lead to increased rearrangements between such repeats. We find that H. pylori UvrD functions to repair DNA damage and limit homologous recombination and DNA damage-induced genomic rearrangements between DNA repeats. Our results suggest that UvrD and other NER pathway proteins play a prominent role in maintaining genome integrity, especially after DNA damage; thus, NER may be especially critical in organisms such as H. pylori that face high-level genotoxic stress in vivo.

Effects of the insecticide permethrin on three life stages of the grass shrimp, Palaemonetes pugio

Toxicity of the pyrethroid insecticide permethrin was assessed using three life stages of the estuarine grass shrimp, Palaemonetes pugio. Adult and larval shrimp were tested with and without sediment. An aqueous embryo test was also conducted. Cellular stress biomarkers, glutathione, and lipid peroxidation, were assessed. Larval shrimp were the most sensitive life stage with a 96-h lethal concentration (LC(50)) value of 0.05 microg/L, compared to 0.25 microg/L for adults, and 6.4 microg/L for embryos. The presence of sediment significantly decreased toxicity of permethrin to both adult and larval shrimp. Permethrin exposure increased time to hatch in embryos and decreased swimming behavior of larvae. Lipid peroxidation levels were significantly decreased in the adult shrimp, but increased in larval shrimp exposed to permethrin. Low levels of permethrin may negatively affect grass shrimp health and survival. Permethrin use in the coastal zone should be carefully managed to avoid adverse impacts on nontarget estuarine organisms.

Latest insights into the effects of Helicobacter pylori infection on gastric carcinogenesis

There appears to be the strong association between Helicobacter pylori (H pylori) and gastric cancer. We reviewed the latest evidences about the effects of H pylori infection on gastric carcinogenesis, classified into epidemiology, dynamics of gastric mucosal changes, DNA damages, virulence factors, host factors, and source of gastric malignancy. Through the considerable progress made in research into virulence factors resulting from differences between H pylori strains, such as cagA positivity, as well as into host factors, such as gene polymorphisms, a diverse spectrum of H pylori-associated diseases, including gastric cancer, is beginning to lend itself to elucidation. The impact of the novel hypothesis advanced by Houghton et al proposing bone-marrow derived stem cells (BMDC) as a potential source of gastric malignancy on evolving research remains to be seen with interest. Further progress in research into H pylori eradication as a viable prophylaxis of gastric cancer, as well as into the mechanisms of gastric carcinogenesis, is to be eagerly awaited for the current year and beyond.

Role of the nrf-2 gene in protection and repair of gastric mucosa against oxidative stress

Helicobacter pylori infection, as well as NSAIDs induce oxidative stress on gastric mucosa, thereby causing mucosal damage and retarding mucosal repair. Cells can survive against chronic oxidative stress by enhancing activities of anti-oxidant enzymes, thereby protecting cells from DNA damage. Recent studies have clearly shown that the gene encoding Nrf-2 (NF-E2 p45-related factor-2) plays an important role in the induction of antioxidant enzymes against oxidative stress. In this paper, we will describe the cellular mechanisms by which the nrf-2 gene stimulates anti-oxidant enzyme activities during exposure to oxidative stress. Secondly, we will also mention the beneficial effects of sulforaphane, an isothiocyanate family which is abundantly included in broccoli sprouts, on gastric mucosa. Sulforaphane stimulates nrf-2 gene-dependent anti-oxidant enzyme activities, thereby protecting cells from oxidative injury. Finally, we will state our perspective on the efficacy of sulforaphane in protection and repair of gastric mucosa against oxidative stress during H. pylori infection.

Differences in oxidative stress dependence between gastric adenocarcinoma subtypes

AIM: To investigate the extent of oxidative stress in pre-neoplastic and neoplastic gastric mucosa in relation to their pathological criteria and histological subtypes.

METHODS: A total of 104 gastric adenocarcinomas from 98 patients (88 infiltrative and 16 intraepithelial tumors) were assessed immunohistochemically for expression of iNOS and occurrence of nitrotyrosine (NTYR)-containing proteins and 8-hydroxy-2’-deoxyguanosine (8-OH-dG)-containing DNA, as markers of NO production and damages to protein and DNA.

RESULTS: Tumor cells staining for iNOS, NTYR and 8-OH-dG were detected in 41%, 62% and 50% of infiltrative carcinoma, respectively. The three markers were shown for the first time in intraepithelial carcinoma. The expression of iNOS was significantly more frequent in tubular carcinoma (TC) compared to diffuse carcinoma (DC) (54% vs 18%; P = 0.008) or in polymorphous carcinoma (PolyC) (54% vs 21%; P = 0.04). NTYR staining was obviously more often found in TC than that in PolyC (72% vs 30%; P=0.03). There was a tendency towards a higher rate of iNOS staining when distant metastasis (pM) was present. In infiltrative TC, the presence of oxidative stress markers was not significantly correlated with histological grade, density of inflammation, the depth of infiltration (pT), lymph nodes dissemination (pN) and pathological stages (pTNM).

CONCLUSION: The iNOS-oxidative pathway may play an important role in TC, but moderately in PolyC and DC. DNA oxidation and protein nitration occur in the three subtypes. Based on the significant differences of NTYR levels, TC and PolyC appear as two distinct subtypes.

Overcoming Fas-mediated apoptosis accelerates Helicobacter-induced gastric cancer in mice

The initiating molecular events in Helicobacter-induced gastric carcinogenesis are not known. Early in infection, Fas antigen-mediated apoptosis depletes parietal and chief cell populations, leading to architectural distortion. As infection progresses, metaplastic and dysplastic glands appear, which are resistant to Fas-mediated apoptosis. These abnormal lineages precede, and are thought to be the precursor lesions of, gastric cancer. Acquisition of an antiapoptotic phenotype before transformation of cells suggests that loss of Fas sensitivity may be an early required trait for gastric cancer. We reasoned that forced Fas-apoptosis resistance would result in earlier and more aggressive gastric cancer in our mouse model. Fas antigen-deficient (lpr) mice or C57BL/6 wild-type mice were irradiated and reconstituted with C57BL/6 marrow forming partial lpr/wt chimera or wt/wt control mice, extending the life span of the lpr and ensuring a competent immune response to Helicobacter felis infection. Infected lpr/wt mice developed gastric cancer as early as 7 months after infection (compared with 15 months in wt/wt mice). At 10 months (90%) and 15 months (100%), mice developed aggressive invasive lesions. This earlier onset and more aggressive histology strongly argues that Fas-apoptosis resistance is an early and important feature of gastric cancer formation.