Oxidative-stress-related proteome changes in Helicobacter pylori-infected human gastric mucosa

Chloride intracellular channels in oncology as potential novel biomarkers and personalized therapy targets: a systematic review

Background

The chloride intracellular channels (CLICs) family includes six ion channels (CLIC1-CLIC6) expressed on the cellular level and secreted into interstitial fluid and blood. They are involved in the physiological functioning of multiple systems as well as the pathogenetic processes of cancer. CLICs play essential roles in the tumor microenvironment. The current systematic review aimed at identifying and summarizing the research of CLICs in oncology on clinical material to assess CLICs' potential as novel biomarkers and personalized therapy targets.

Materials and methods

The authors systematically searched the PubMed database for original articles concerning CLIC research on clinical material of all types of cancer - fluids and tissues.

Results

Fifty-three articles investigating in summary 3944 clinical samples were qualified for the current review. Studied material included 3438 tumor samples (87%), 437 blood samples (11%), and 69 interstitial fluid samples (2%). Studies investigated 21 cancer types, mostly hepatocellular carcinoma, colorectal, ovarian, and gastric cancer. Importantly, CLIC1, CLIC2, CLIC3, CLIC4, and CLIC5 were differently expressed in cancerous tissues and patients' blood compared to healthy controls. Moreover, CLICs were found to be involved in several cancer-associated signaling pathways, such as PI3K/AKT, MAPK/ERK, and MAPK/p38.

Conclusion

CLIC family members may be candidates for potential novel cancer biomarkers due to the contrast in their expression between cancerous and healthy tissues and secretion to the interstitial fluid and blood. CLICs are investigated as potential therapeutic targets because of their involvement in cancer pathogenesis and tumor microenvironment.

Bacteria-Mediated Oncogenesis and the Underlying Molecular Intricacies: What We Know So Far

Cancers are known to have multifactorial etiology. Certain bacteria and viruses are proven carcinogens. Lately, there has been in-depth research investigating carcinogenic capabilities of some bacteria. Reports indicate that chronic inflammation and harmful bacterial metabolites to be strong promoters of neoplasticity. Helicobacter pylori-induced gastric adenocarcinoma is the best illustration of the chronic inflammation paradigm of oncogenesis. Chronic inflammation, which produces excessive reactive oxygen species (ROS) is hypothesized to cause cancerous cell proliferation. Other possible bacteria-dependent mechanisms and virulence factors have also been suspected of playing a vital role in the bacteria-induced-cancer(s). Numerous attempts have been made to explore and establish the possible relationship between the two. With the growing concerns on anti-microbial resistance and over-dependence of mankind on antibiotics to treat bacterial infections, it must be deemed critical to understand and identify carcinogenic bacteria, to establish their role in causing cancer.

Recent developments in Phos-tag electrophoresis for the analysis of phosphoproteins in proteomics

INTRODUCTION

Phosphate-binding tag (Phos-tag) sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) is an important development capable of analyzing the phosphorylation state of proteins. Conventionally, proteins were separated via SDS-PAGE and Phos-tag SDS-PAGE that use different gels to identify phosphorylated proteins. However, it was often difficult to compare the electrophoretic mobility of the proteins in the different gels used. The recently developed Phos-tag diagonal electrophoresis has been able to solve this problem. It can indicate the SDS-PAGE and Phos-tag SDS-PAGE patterns on a single gel; therefore, phosphorylated proteins can be distinguished easily from non-phosphorylated proteins.

AREAS COVERED

This review assesses the importance of Phos-tag electrophoresis, which enables the analysis of protein phosphorylation states, in the field of proteomics. Additionally, this review describes the significance and actual experimental technique of Phos-tag diagonal electrophoresis, which was recently developed to overcome the drawbacks of Phos-tag SDS-PAGE.

EXPERT OPINION

Although shotgun analysis of proteins allows detecting many phosphorylation sites, it is challenging to clarify the differences in the phosphorylation states of protein molecules using this technique. Therefore, Phos-tag SDS-PAGE is frequently used to determine the phosphorylation state of proteins. This technique has become more powerful with the recent development of Phos-tag diagonal electrophoresis.

Gastric Helicobacter suis Infection Partially Protects against Neurotoxicity in A 6-OHDA Parkinson's Disease Mouse Model

The exact etiology of Parkinson’s disease (PD) remains largely unknown, but more and more research suggests the involvement of the gut microbiota. Interestingly, idiopathic PD patients were shown to have at least a 10 times higher prevalence of Helicobacter suis (H. suis) DNA in gastric biopsies compared to control patients. H. suis is a zoonotic Helicobacter species that naturally colonizes the stomach of pigs and non-human primates but can be transmitted to humans. Here, we investigated the influence of a gastric H. suis infection on PD disease progression through a 6-hydroxydopamine (6-OHDA) mouse model. Therefore, mice with either a short- or long-term H. suis infection were stereotactically injected with 6-OHDA in the left striatum and sampled one week later. Remarkably, a reduced loss of dopaminergic neurons was seen in the H. suis/6-OHDA groups compared to the control/6-OHDA groups. Correspondingly, motor function of the H. suis-infected 6-OHDA mice was superior to that in the non-infected 6-OHDA mice. Interestingly, we also observed higher expression levels of antioxidant genes in brain tissue from H. suis-infected 6-OHDA mice, as a potential explanation for the reduced 6-OHDA-induced cell loss. Our data support an unexpected neuroprotective effect of gastric H. suis on PD pathology, mediated through changes in oxidative stress.

β-Carotene Inhibits Expression of Matrix Metalloproteinase-10 and Invasion in Helicobacter pylori-Infected Gastric Epithelial Cells

Matrix metalloproteinases (MMPs), key molecules of cancer invasion and metastasis, degrade the extracellular matrix and cell–cell adhesion molecules. MMP-10 plays a crucial role in Helicobacter pylori-induced cell-invasion. The mitogen-activated protein kinase (MAPK) signaling pathway, which activates activator protein-1 (AP-1), is known to mediate MMP expression. Infection with H. pylori, a Gram-negative bacterium, is associated with gastric cancer development. A toxic factor induced by H. pylori infection is reactive oxygen species (ROS), which activate MAPK signaling in gastric epithelial cells. Peroxisome proliferator-activated receptor γ (PPAR-γ) mediates the expression of antioxidant enzymes including catalase. β-Carotene, a red-orange pigment, exerts antioxidant and anti-inflammatory properties. We aimed to investigate whether β-carotene inhibits H. pylori-induced MMP expression and cell invasion in gastric epithelial AGS (gastric adenocarcinoma) cells. We found that H. pylori induced MMP-10 expression and increased cell invasion via the activation of MAPKs and AP-1 in gastric epithelial cells. Specific inhibitors of MAPKs suppressed H. pylori-induced MMP-10 expression, suggesting that H. pylori induces MMP-10 expression through MAPKs. β-Carotene inhibited the H. pylori-induced activation of MAPKs and AP-1, expression of MMP-10, and cell invasion. Additionally, it promoted the expression of PPAR-γ and catalase, which reduced ROS levels in H. pylori-infected cells. In conclusion, β-carotene exerts an inhibitory effect on MAPK-mediated MMP-10 expression and cell invasion by increasing PPAR-γ-mediated catalase expression and reducing ROS levels in H. pylori-infected gastric epithelial cells.

Vicenin-2 inhibits the Helicobacterium pylori infection associated gastric carcinogenic events through modulation of PI3K/AKT and Nrf2 signaling in GES-1 cells

Helicobacter pylori (H. pylori), a microbial carcinogen of Gram-negative bacteria, has been recognized to be the highest risk factor for the growth of human gastric cancer (GC). Therefore, the inhibition of the growth rate of H. pylori has been considered an effective vital strategy to prevent GC development. This study highlights the inhibitory effect of vicenin-2 against H. pylori-induced gastric carcinogen signaling in human gastric epithelial cells (GES-1). In vitro cytotoxicity studies reported that 40 µM of vicenin-2  remarkably protects the gastric cells and this concentration shows 85% cell viability also does not produce toxicity. In addition, vicenin-2 prevents H. pylori-infected increased depletion of antioxidants mediated by reactive oxygen species generation, DNA damage, malondialdehyde, and nuclear fragmentation. Here, we noticed that vicenin-2 remarkably suppressed the expression range of the phosphorylated form of phosphatidylinositol 3-kinase/protein kinase B, phosphorylated p38 kinases, phosphorylated extracellular signal-regulated kinase-1, phosphorylated c-Jun N-terminal kinase, tumor necrosis factor-α, interleukin-6, cyclooxygenase-2 in GES-1 infected with H. pylori. Moreover, we observed that vicenin-2 enhanced the antioxidants protein nuclear factor erythroid factor-2 and phosphatase and tensin homolog expression in H. pylori-infected cells. Thus, vicenin-2 prevents the H. pylori-associated infection, and its resistance might be a potential strategy in preventing GC induced by H. pylori.

Cellular stress and redox activity proteins are involved in gastric carcinogenesis associated with Helicobacter pylori infection expressing high levels of thioredoxin-1

Helicobacter pylori infection is related to the development of gastric diseases. Our previous studies showed that high thioredoxin-1 (Trx1) expression in H. pylori can promote gastric carcinogenesis. To explore the underlying molecular mechanisms, we performed an isobaric tags for relative and absolute quantitation (iTRAQ)-based quantitative proteomic analysis of stomach tissues from Mongolian gerbil infected with H. pylori expressing high and low Trx1. Differences in the profiles of the expressed proteins were analyzed by bioinformatics and verified using Western blot analysis. We found three candidate proteins, 14-3-3α/β, glutathione-S-transferase (GST), and heat shock protein 70 (HSP70), in high Trx1 tissues compared with low Trx1 tissues and concluded that cellular stress and redox activity-related proteins were involved in the pathogenesis of gastric cancer associated with H. pylori Trx1.

Helicobacter pylori and Gastric Cancer: Adaptive Cellular Mechanisms Involved in Disease Progression

Helicobacter pylori (H. pylori) infection is the major risk factor associated with the development of gastric cancer. The transition from normal mucosa to non-atrophic gastritis, triggered primarily by H. pylori infection, initiates precancerous lesions which may then progress to atrophic gastritis and intestinal metaplasia. Further progression to dysplasia and gastric cancer is generally believed to be attributable to processes that no longer require the presence of H. pylori. The responses that develop upon H. pylori infection are directly mediated through the action of bacterial virulence factors, which drive the initial events associated with transformation of infected gastric cells. Besides genetic and to date poorly defined environmental factors, alterations in gastric cell stress-adaptive mechanisms due to H. pylori appear to be crucial during chronic infection and gastric disease progression. Firstly, H. pylori infection promotes gastric cell death and reduced epithelial cell turnover in the majority of infected cells, resulting in primary tissue lesions associated with an initial inflammatory response. However, in the remaining gastric cell population, adaptive responses are induced that increase cell survival and proliferation, resulting in the acquisition of potentially malignant characteristics that may lead to precancerous gastric lesions. Thus, deregulation of these intrinsic survival-related responses to H. pylori infection emerge as potential culprits in promoting disease progression. This review will highlight the most relevant cellular adaptive mechanisms triggered upon H. pylori infection, including endoplasmic reticulum stress and the unfolded protein response, autophagy, oxidative stress, and inflammation, together with a subsequent discussion on how these factors may participate in the progression of a precancerous lesion. Finally, this review will shed light on how these mechanisms may be exploited as pharmacological targets, in the perspective of opening up new therapeutic alternatives for non-invasive risk control in gastric cancer.

Proteotoxicity in cardiac amyloidosis: amyloidogenic light chains affect the levels of intracellular proteins in human heart cells

AL amyloidosis is characterized by widespread deposition of immunoglobulin light chains (LCs) as amyloid fibrils. Cardiac involvement is frequent and leads to life-threatening cardiomyopathy. Besides the tissue alteration caused by fibrils, clinical and experimental evidence indicates that cardiac damage is also caused by proteotoxicity of prefibrillar amyloidogenic species. As in other amyloidoses, the damage mechanisms at cellular level are complex and largely undefined. We have characterized the molecular changes in primary human cardiac fibroblasts (hCFs) exposed in vitro to soluble amyloidogenic cardiotoxic LCs from AL cardiomyopathy patients. To evaluate proteome alterations caused by a representative cardiotropic LC, we combined gel-based with label-free shotgun analysis and performed bioinformatics and data validation studies. To assess the generalizability of our results we explored the effects of multiple LCs on hCF viability and on levels of a subset of cellular proteins. Our results indicate that exposure of hCFs to cardiotropic LCs translates into proteome remodeling, associated with apoptosis activation and oxidative stress. The proteome alterations affect proteins involved in cytoskeletal organization, protein synthesis and quality control, mitochondrial activity and metabolism, signal transduction and molecular trafficking. These results support and expand the concept that soluble amyloidogenic cardiotropic LCs exert toxic effects on cardiac cells.

Application of proteomics to the study of Helicobacter pylori and implications for the clinic

INTRODUCTION

Helicobacter pylori (H. pylori) is a gram-negative bacterium that colonizes the gastric epithelium and mucous layer of more than half the world's population. H. pylori is a primary human pathogen, responsible for the development of chronic gastritis, peptic ulceration and gastric cancer. Proteomics is impacting several aspects of medical research: understanding the molecular basis of infection and disease manifestation, identification of therapeutic targets and discovery of clinically relevant biomarkers. Areas covered: The main aim of the present review is to provide a comprehensive overview of the contribution of proteomics to the study of H. pylori infection pathophysiology. In particular, we focused on the role of the bacterium and its most important virulence factor, CagA, in the progression of gastric cells transformation and cancer progression. We also discussed the proteomic approaches aimed at the investigation of the host response to bacterial infection. Expert commentary: In the field of proteomics of H. pylori, comprehensive analysis of clinically relevant proteins (functional proteomics) rather than entire proteomes will result in important medical outcomes. Finally, we provided an outlook on the potential development of proteomics in H. pylori research.

The Helicobacter pylori cytotoxin CagA is essential for suppressing host heat shock protein expression

Bacterial infections typically elicit a strong Heat Shock Response (HSR) in host cells. However, the gastric pathogen Helicobacter pylori has the unique ability to repress this response, the mechanism of which has yet to be elucidated. This study sought to characterize the underlying mechanisms by which H. pylori down-modulates host HSP expression upon infection. Examination of isogenic mutant strains of H. pylori defective in components of the type IV secretion system (T4SS), identified the secretion substrate, CagA, to be essential for down-modulation of the HSPs HSPH1 (HSP105), HSPA1A (HSP72), and HSPD1 (HSP60) upon infection of the AGS gastric adenocarcinoma cell line. Ectopic expression of CagA by transient transfection was insufficient to repress HSP expression in AGS or HEK293T cells, suggesting that additional H. pylori factors are required for HSP repression. RT-qPCR analysis of HSP gene expression in AGS cells infected with wild-type H. pylori or isogenic cagA-deletion mutant found no significant change to account for reduced HSP levels. In summary, this study identified CagA to be an essential bacterial factor for H. pylori-mediated suppression of host HSP expression. The novel finding that HSPH1 is down-modulated by H. pylori further highlights the unique ability of H. pylori to repress the HSR within host cells. Elucidation of the mechanism by which H. pylori achieves HSP repression may prove to be beneficial in the identification of novel mechanisms to inhibit the HSR pathway and provide further insight into the interactions between H. pylori and the host gastric epithelium.

Helicobacter pylori infection and gastric carcinoma: Not all the strains and patients are alike

Gastric carcinoma (GC) develops in only 1%-3% of Helicobacter pylori (H. pylori) infected people. The role in GC formation of the bacterial genotypes, gene polymorphisms and host's factors may therefore be important. The risk of GC is enhanced when individuals are infected by strains expressing the oncoprotein CagA, in particular if CagA has a high number of repeats containing the EPIYA sequence in its C'-terminal variable region or particular amino acid sequences flank the EPIYA motifs. H. pylori infection triggers an inflammatory response characterised by an increased secretion of some chemokines by immunocytes and colonised gastric epithelial cells; these molecules are especially constituted by proteins composing the interleukin-1beta (IL-1β) group and tumour necrosis factor-alpha (TNF-α). Polymorphisms in the promoter regions of genes encoding these molecules, could account for high concentrations of IL-1β and TNF-α in the gastric mucosa, which may cause hypochlorhydria and eventually GC. Inconsistent results have been attained with other haplotypes of inflammatory and anti-inflammatory cytokines. Genomic mechanisms of GC development are mainly based on chromosomal or microsatellite instability (MSI) and deregulation of signalling transduction pathways. H. pylori infection may induce DNA instability and breaks of double-strand DNA in gastric mucocytes. Different H. pylori strains seem to differently increase the risk of cancer development run by the host. Certain H. pylori genotypes (such as the cagA positive) induce high degrees of chronic inflammation and determine an increase of mutagenesis rate, oxidative-stress, mismatch repair mechanisms, down-regulation of base excision and genetic instability, as well as generation of reactive oxygen species that modulate apoptosis; these phenomena may end to trigger or concur to GC development.

[Proteomics analysis for Helicobacter pylori-infected gastric mucosa]

BACKGROUND/AIMS

Helicobacter pylori infection is linked to the development of gastric cancer. H. pylori-associated gastric inflammation is considered to be the first important step in the histogenesis of such neoplasia. However, studies that compare proteome of gastric mucosa infected with or without H. pylori are lacking.

METHODS

We employed proteomics analysis on the endoscopic biopsy specimens of gastric mucosa obtained from two groups (30 cases): healthy subjects without H. pylori infection (15 cases), and gastritis patients with H. pylori infection (15 cases). The pooled proteins obtained from gastric mucosa infected with or without H. pylori were separated by two-dimensional gel electrophoresis and analyzed by a computer-aided program. The altered protein expressions were then identified by mass spectrometry and validated by Western blotting and immunohistochemistry.

RESULTS

On mass spectrometry using MALDI TOF™ Analyzer, the up-regulation of Keratin 1, ezrin, adenosine triphosphate (ATP) synthase subunit alpha mitochondrial isoform c, Keratin type I cytoskeletal 19, and Keratin type I cytoskeletal 9 were identified; in contrast, 71 kd heat shock cognate protein, ATP synthase subunit alpha mitochondrial precursor, and annexin IV were down-regulated. Among them, membrane cytoskeleton linker ezrin was validated using Western blot and immunohistochemistry.

CONCLUSIONS

Expression of ezrin was significantly different between the gastric mucosa with and without H. pylori infection. Therefore, ezrin could be considered a promising potential molecular marker for detecting H. pylori infection in gastric mucosa.

Helicobacter pylori-an infectious risk factor for atherosclerosis?

Accumulating evidence implicates Helicobacter pylori (H. pylori) infection in the pathogenesis of certain diseases localized outside the stomach, particularly those characterized by persistent and low-grade systematic inflammation. Recently, the role of H. pylori infection in the development of atherosclerosis and its clinical complications has received attention. Atherosclerosis is a high-cost disease, and acute events resulting from this condition rank first among morbidity and mortality statistics in most industrialized countries. Atherosclerosis is a multifactorial disorder, and traditional risk factors explain only 50% of its etiology. Therefore, identifying new risk factors for atherosclerosis is necessary. Serological studies indicate that chronic H. pylori infection, especially that with more virulent strains, may predispose patients to the onset of atherosclerosis and related adverse clinical events, and PCR studies have detected H. pylori DNA in atherosclerotic plaques, although this finding remains controversial. If this association were to be confirmed, its importance to public health would be substantial, as the eradication of H. pylori is more straightforward and less costly than the long-term treatment of other risk factors. This review investigates the potential relationship between H. pylori infection and atherosclerosis from both epidemiological and pathogenic perspectives and characterizes the potential mechanisms underlying this correlation.

Testosterone and vitamin E administration up-regulated varicocele-reduced Hsp70-2 protein expression and ameliorated biochemical alterations

PURPOSE

This study was designed to evaluate the protective effects of vitamin E (VitE) and testosterone on varicocele (VCL)-induced damage in testis and sperm parameters and their effects on Hsp70-2 chaperone expression and on antioxidant status.

METHODS

Wistar rats were divided into five groups: control-sham, VCL-induced, VitE-treated varicocelized (150 mg/kg, orally), testosterone-administrated varicocelized (400 μg/kg, intraperitoneally) and VitE + testosterone-received VCL-induced rats. The sperm count, DNA integrity, motility, viability and histone-protamine transition were evaluated after 60 days. The antioxidant status was analyzed by determining testicular malondialdehyde (MDA), total antioxidant capacity (TAC), superoxide desmutase (SOD) and glutathione peroxidase (GSH-Px). Endocrine status of the testicular tissue was estimated by evaluating the Leydig cells steroidogenic activity using fluorescent analyses for cytoplasmic steroid foci and by determination of serum testosterone. The expression of Hsp70-2 protein was analyzed using imunohistochemical and western blot analyses. RNA damage of the germinal cells was examined with epi-fluorescent examination.

RESULTS

VitE and testosterone administration ameliorated the varicocele-reduced Leydig cell and testosterone level. In addition, co-administration of these compounds recovered the VCL-induced reduction of TAC, SOD, and GSH-px and lowered significantly (P < 0.05) the VCL-elevated content of MDA. The treated animals revealed with a significant (P < 0.05) up-regulation of the VCL-reduced expression of Hsp70-2 protein. Moreover, VitE and testosterone significantly (P < 0.05) inhibited the VCL-increased RNA damage in germinal cells.

CONCLUSION

Our data suggest that the protective effects of VitE and testosterone on VCL-induced derangements may depend on enhancing testicular antioxidant status and up-regulating endocrine activities, which enhanced the Hsp70-2 chaperone expression.

The phenyl-thiophenyl propenone RK-I-123 reduces the levels of reactive oxygen species and suppresses the activation of NF-κB and AP-1 and IL-8 expression in Helicobacter pylori-infected gastric epithelial AGS cells

OBJECTIVE

To investigate whether the phenyl-thiophenyl propenone RK-I-123 suppresses interleukin-8 (IL-8) expression and activation of mitogen-activated protein kinases (MAPKs) and transcription factors (nuclear factor-κB [NF-κB] and activator protein-1 [AP-1]) by reducing reactive oxygen species (ROS) levels in Helicobacter pylori-infected gastric epithelial cells.

MATERIAL

Helicobacter pylori in Korean isolates, human gastric epithelial AGS cells.

TREATMENT

AGS cells pretreated with or without RK-I-123 were cultured in the presence of H. pylori at a bacterium/cell ratio of 300:1.

METHODS

Reactive oxygen species and IL-8 levels were determined by dichlorofluorescein fluorescence and enzyme-linked immunosorbent assay. The IL-8 mRNA expression was analyzed by the real-time reverse transcription-polymerase chain reaction (RT-PCR). The MAPK and IκBα levels were determined by western blotting. The activation of NF-κB and AP-1 was determined by the electrophoretic mobility shift assay.

RESULTS

Helicobacter pylori induced an increase in ROS and IL-8 expression and activation of MAPKs and transcription factors (NF-κB and AP-1) together with the degradation of IκBα in AGS cells, all of which were inhibited by RK-I-123.

CONCLUSIONS

The RK-I-123 suppressed the H. pylori-induced IL-8 expression and activation of MAPKs, NF-κB, and AP-1 by reducing ROS levels in AGS cells. The RK-I-123 may be a potential candidate for the treatment of H. pylori-induced gastric inflammation.

Contribution of proteomics to the study of the role of cytokeratins in disease and physiopathology

Cytokeratins (CKs), the most abundant group of cytoskeletal intermediate filaments, and proteomics are strongly connected. On the one hand, proteomics has been extremely useful to uncover new features and functions of CKs, on the other, the highly abundant CKs serve as an exceptional tool to test new technological developments in proteomics. As a result, proteomics has contributed to finding valuable associations of CKs with diseases as diverse as cancer, cystic fibrosis, steatohepatitis, viral and bacterial infection, keratoconus, vitreoretinopathy, preeclampsia or the chronic fatigue syndrome, as well as to characterizing their participation in a number of physiopathological processes, including drug resistance, response to toxicants, inflammation, stem cell differentiation, embryo development, and tissue repair. In some cases, like in cystic fibrosis, CKs have been described as potential therapeutic targets. The development of a specific field of proteomics where CKs become the main subject of research aims and hypotheses is suggested.

Proteomic changes in rat spermatogenesis in response to in vivo androgen manipulation; impact on meiotic cells

The production of mature sperm is reliant on androgen action within the testis, and it is well established that androgens act on receptors within the somatic Sertoli cells to stimulate male germ cell development. Mice lacking Sertoli cell androgen receptors (AR) show late meiotic germ cell arrest, suggesting Sertoli cells transduce the androgenic stimulus co-ordinating this essential step in spermatogenesis. This study aimed to identify germ cell proteins responsive to changes in testicular androgen levels and thereby elucidate mechanisms by which androgens regulate meiosis. Testicular androgen levels were suppressed for 9 weeks using testosterone and estradiol-filled silastic implants, followed by a short period of either further androgen suppression (via an AR antagonist) or the restoration of intratesticular testosterone levels. Comparative proteomics were performed on protein extracts from enriched meiotic cell preparations from adult rats undergoing androgen deprivation and replacement in vivo. Loss of androgenic stimulus caused changes in proteins with known roles in meiosis (including Nasp and Hsp70–2), apoptosis (including Diablo), cell signalling (including 14-3-3 isoforms), oxidative stress, DNA repair, and RNA processing. Immunostaining for oxidised DNA adducts confirmed spermatocytes undergo oxidative stress-induced DNA damage during androgen suppression. An increase in PCNA and an associated ubiquitin-conjugating enzyme (Ubc13) suggested a role for PCNA-mediated regulation of DNA repair pathways in spermatocytes. Changes in cytoplasmic SUMO1 localisation in spermatocytes were paralleled by changes in the levels of free SUMO1 and of a subunit of its activating complex, suggesting sumoylation in spermatocytes is modified by androgen action on Sertoli cells. We conclude that Sertoli cells, in response to androgens, modulate protein translation and post-translational events in spermatocytes that impact on their metabolism, survival, and completion of meiosis.

Genetic aspects of gastric cancer instability

Unravelling the molecular mechanisms underlying gastric carcinogenesis is one of the major challenges in cancer genomics. Gastric cancer is a very complex and heterogeneous disease, and although much has been learned about the different genetic changes that eventually lead to its development, the detailed mechanisms still remain unclear. Malignant transformation of gastric cells is the consequence of a multistep process involving different genetic and epigenetic changes in numerous genes in combination with host genetic background and environmental factors. The majority of gastric adenocarcinomas are characterized by genetic instability, either microsatellite instability (MSI) or chromosomal instability (CIN). It is believed that chromosome destabilizations occur early in tumour progression. This review summarizes the most common genetic alterations leading to instability in sporadic gastric cancers and its consequences.

Ribosomal genes and heat shock proteins as putative markers for chronic, sublethal heat stress in Arctic charr: applications for aquaculture and wild fish

Arctic charr thrive at high densities and can live in freshwater year round, making this species especially suitable for inland, closed containment aquaculture. However, it is a cold-water salmonid, which both limits where the species can be farmed and places wild populations at particular risk to climate change. Previously, we identified genes associated with tolerance and intolerance to acute, lethal temperature stress in Arctic charr. However, there remained a need to examine the genes involved in the stress response to more realistic temperatures that could be experienced during a summer heat wave in grow-out tanks that are not artificially cooled, or under natural conditions. Here, we exposed Arctic charr to sublethal heat stress of 15-18°C for 72 h, and gill tissues extracted before, during (i.e., at 72 h), immediately after cooling and after 72 h of recovery at ambient temperature (6°C) were used for gene expression profiling by microarray and qPCR analyses. The results revealed an expected pattern for heat shock protein expression, which was highest during heat exposure, with significantly reduced expression (approaching control levels) quickly thereafter. We also found that the expression of numerous ribosomal proteins was significantly elevated immediately and 72 h after cooling, suggesting that the gill tissues were undergoing ribosome biogenesis while recovering from damage caused by heat stress. We suggest that these are candidate gene targets for the future development of genetic markers for broodstock development or for monitoring temperature stress and recovery in wild or cultured conditions.

Antibodies against Helicobacter pylori heat shock protein 60 aggravate HSP60-mediated proinflammatory responses

Anti-Helicobacter pylori heat shock protein 60 (HpHSP60) antibodies are usually found in H. pylori-infected patients and are known to be associated with the progression of gastric diseases. However, the effects of these antibodies on the functions of HpHSP60 have not been identified. This study aims to investigate the effects of the interaction between anti-HSP60 antibodies and HpHSP60 on inflammatory responses. Anti-HpHSP60 polyclonal sera and monoclonal antibodies (mAbs) were produced to evaluate their effects on HpHSP60-induced IL-8 and TNF-α activity. The results indicated that anti-HpHSP60 polyclonal sera collected from patients infected with H. pylori or from rabbit and mice immunized with HpHSP60 could significantly enhance HpHSP60-mediated IL-8 and TNF-α secretion from monocytic THP-1 cells. Similar effects were also found with anti-HpHSP60 mAbs. Further analysis revealed that this phenomenon was only carried out by anti-HpHSP60 antibody but not by other non-specific mAbs. Moreover, the non-specific mAbs decreased the synergism of HpHSP60 and anti-HpHSP60 mAbs in proinflammatory cytokine induction. Herein, we have examined the role of anti-HpHSP60 antibody in host immune responses for the first time. This study demonstrated that H. pylori HSP60/mAbs could modulate helicobacterial pathogenesis by increasing IL-8 and TNF-α production. The pathogen-specific antibodies may execute potential immune functions rather than recognize or neutralize microbes.

Helicobacter pylori in a Korean isolate expressed proteins differentially in human gastric epithelial cells

PURPOSE

The proteins expressed in gastric epithelial cells infected with Helicobacter pylori (H. pylori) may determine the clinical outcome such as chronic gastritis, peptic ulcer, and gastric carcinoma. The present study aims to determine the differentially expressed proteins in human gastric epithelial AGS cells that were infected with H. pylori in a Korean isolate, a cagA+, vacA s1b m2 iceA1 H. pylori by proteomic analysis. The differentially expressed proteins, whose expression levels were more or less than twofold in H. pylori-infected cells, were analyzed.

RESULTS

Ten proteins (chromatin assembly factor-1, proliferating cell nuclear antigen, 14-3-3 protein tau, eukaryotic translation initiation factor 6, heat-shock protein 90beta, dimethylarginine dimethylaminohydrolase-1, L-lactate dehydrogenase B chain, prohibitin, triosephosphate isomerase, protein disulfide isomerase) were up-regulated while eight proteins (heat-shock gp96 precursor, nucleophosmin, ornithine aminotransferase, Ku70, L-arginine-glycine amidinotransferase, Smad anchor for receptor activation, ADP-ribosylation factor, WD repeat-containing protein isoform 1) were down-regulated by H. pylori infection in AGS cells. These proteins are related to cell proliferation, cell adhesion, carcinogenesis, cell-defense mechanisms against oxidative stress, membrane trafficking, and energy metabolism.

CONCLUSIONS

Oxidative stress, cell proliferation, cell adhesion, and membrane trafficking may be involved in the pathogenesis of gastric diseases including cancer associated with H. pylori in a Korean isolate.

Immune reactions against elongation factor 2 kinase: specific pathogenesis of gastric ulcer from Helicobacter pylori infection

Helicobacter pylori (H. pylori) infection is a definite causative factor for gastric ulcers (GUs). In the present study we detected a specific antigen of gastric epithelial cells (HGC-27) using cell ELISA, which was recognized by the sera of GU patients (n = 20) but not in patients with chronic gastritis (CG; n = 20) or in healthy volunteers (HC; n = 10). This antigen was over-expressed by a stressful (heat-stressed) environment, and was identified as elongation factor 2 kinase (EF-2K) by western blotting. The GU patients' lymphocytes stimulated by H. pylori specifically disrupted heat-stressed HGC-27 cells in a cytotoxic assay. In flow cytometry, the effector cells (lymphocytes) from GU patients were significantly differentiated to T helper type 1 lymphocyte (Th1) and cytotoxic T lymphocyte (CTL) as opposed to those from CG patients. The target cells (HGC-27) expressed EF-2K and MHC-class I together with costimulatory molecules from heat stress. This antigen specific immune mechanism could have a prominent role in the pathogenesis of GU.

Microarray based analysis of temperature and oxidative stress induced messenger RNA in Schistosoma mansoni

The body's defense against schistosome infection can take many forms. For example, upon developing acute schistosomiasis, patients often have fever coinciding with larval maturation, migration and early oviposition. As the infection becomes established, the parasite comes under oxidative stress generated by the host immune system. The most common treatment for schistosomiasis is the anti-helminthic drug praziquantel. Its effectiveness, however, is limited due to its inability to kill schistosomes 2-4 weeks post-infection. Clearly there is a need for new anti-schistosomal drugs. We hypothesize that gene products expressed as part of a protective response against heat and/or oxidative stress are potential therapeutic targets for future drug development. Using a 12,166 element oligonucleotide microarray to characterize Schistosoma mansoni genes induced by heat and oxidative stress we found that 1878 S. mansoni elements were significantly induced by heat stress. These included previously reported heat-shock genes expressing homologs of HSP40, HSP70 and HSP86. One thousand and one elements were induced by oxidative stress including those expressing homologs of superoxide dismutase, glutathione peroxidase and aldehyde dehydrogenase. Seventy-two elements were common to both stressors and could potentially be exploited in the development of novel anti-schistosomal therapeutics.

Expression of suppressors of cytokine signaling-3 in Helicobacter pylori-infected rat gastric mucosal RGM-1cells

Our previous studies show that Helicobacter pylori (H. pylori) induces oxidative stress and the expression of proinflammatory cytokines in gastric epithelial cells. H. pylori induces the expression of molecular chaperones and proteins involved in protein-folding machinery as a defense mechanism against cellular stress. The suppressors of cytokine signaling (SOCS) are known as negative regulators of major immune signal pathways. The purpose of this article is to determine whether H. pylori in a Korean isolate (HP99) induces the expression of SOCS in rat gastric mucosal RGM-1 cells as a defense mechanism. As a result, HP99 induced SOCS-3 expression time-dependently in RGM-1 cells. SOCS-1 was not expressed while SOCS-2 expression was not changed by HP99 infection in RGM-1 cells. SOCS-3 might have a defensive role in H. pylori-infected gastric mucosal cells. Further study by manipulating SOCS-3 gene should be performed to investigate the physiological meaning of SOCS-3 induced by H. pylori in gastric mucosal cells.

Interaction between the Helicobacter pylori CagA and alpha-Pix in gastric epithelial AGS cells

The gastric pathogen Helicobacter pylori (H. pylori) translocates the CagA protein into epithelial cells by a type IV secretion process. Upon translocation into the host cell cytosol, CagA undergoes tyrosine phosphorylation. Phosphorylation of CagA occurs within the C terminus of the protein and is mediated by members of the Src family of tyrosine kinases. Phosphorylation of CagA induces the dephosphorylation of as yet unidentified cellular proteins, rearrangements of the host cell actin cytoskeleton, and cell scattering. This article aims to determine the cellular protein that interacts with CagA. Gastric epithelial AGS cells were stimulated with CagA-positive H. pylori (NCTC11637, at a bacteria/cell ratio of 500:1) and cultured in antibiotic-free medium. Proteins were isolated from the cells with or without H. pylori infection. CagA-interactive protein was determined by immunoprecipitation using anti-CagA antibody and proteomic analysis. We found that alpha-Pix interacts with CagA and alpha-Pix was constitutively expressed in AGS cells. Upon H. pylori stimulation, CagA was translocated into the cells and the expression of alpha-Pix (PAK-interactive exchange factor) was increased in AGS cells time dependently. The interaction of alpha-Pix with CagA was increased by H. pylori infection in AGS cells. Phosphorylation of CagA induces the dephosphorylation of alpha-Pix in AGS cells. alpha-Pix is a family of PAK-binding proteins that strongly activates PAK (p21-activated tyrosine kinase). PAK regulates changes in gene expression and mediates actin cytoskeletal and cell morphological changes. The novel finding of this study is that phosphorylation of CagA induces the dephosphorylation of alpha-Pix, which may modulate cytoskeletal changes of gastric epithelial cells through PAK.

Proteomic analysis of proteins regulated by TRPS1 transcription factor in DU145 prostate cancer cells

The aim of the present study was to identify proteins differentially regulated by TRPS1 in human prostate cancer cells in order to better understand the role of TRPS1 in prostate cancer development. The proteomes of androgen-independent DU145 prostate cancer cells, that do not express TRPS1 and of genetically engineered DU145 cells that stable and inducible express recombinant TRPS1 protein, were compared. Using two-dimensional electrophoresis followed by mass spectrometric analysis, 13 proteins that were differentially expressed between these two cell lines were identified. These proteins represent a dominant reduction of expression of antioxidant proteins, including superoxide dismutase, protein disulfide isomerase A3 precursor, endoplasmin precursor and annexin A2. Furthermore, regulation was observed for mitochondrion-associated proteins, glycolytic enzymes, a cytoskeleton-associated protein, a nuclear protein and proteins involved in apoptosis. Our data indicate that overexpression of TRPS1 protein is correlated with reduced protein expression of certain antioxidants. This suggests a possible involvement of TRPS1 in oxidative stress, and possibly in apoptosis in androgen-independent DU145 prostate cancer cells.

Proteomic alteration in gastic adenocarcinomas from Japanese patients

Background

Gastric adenocarcinomas comprise one of the common types of cancers in Asian countries including Japan. Comprehensive protein profiling of paired surgical specimens of primary gastric adenocarcinomas and nontumor mucosae derived from Japanese patients was carried out by means of two-dimensional gel electrophoresis (2D-EP) and liquid chromatography-electrospray ionic tandem mass spectrometry (LC-ESI-MS) to establish gastric cancer-specific proteins as putative clinical biomarkers and molecular targets for chemotherapy.

Results

Relatively common alterations in protein expression were revealed in the tumor tissues. Increases in manganese dismutase and nonhistone chromosomal protein HMG-1 (HMG-1) were observed, while decreases in carbonic anhydrases I and II, glutatione-S-transferase and foveolin precursor (gastrokine-1) (FOV), an 18-kDa stomach-specific protein with putative tumor suppressor activity, were detected. RT-PCR analysis also revealed significant down-regulation of FOV mRNA expression in tumor tissues.

Conclusion

A possible pathological role for down-regulation of FOV in gastric carcinogenesis was demonstrated. Evaluation of the specific decreases in gene and protein expression of FOV in patients may be utilized as clinical biomarkers for effective diagnosis and assessment of gastric cancer.

The Reaction of Hydrogen Atoms with Methionine Residues: A Model of Reductive Radical Stress Causing Tandem Protein-Lipid Damage

The occurrence of tandem damage, due to reductive radical stress involving proteins and lipids, is shown by using a biomimetic model. It is made of unsaturated lipid vesicle suspensions in phosphate buffer in the presence of methionine, either as a single amino acid or as part of a protein such as RNase A, which contains four methionine residues. The radical process starts with the formation of H(.) atoms by reaction of solvated electrons with dihydrogen phosphate anions, which selectively attack the thioether function of methionine. The modification of methionine to alpha-aminobutyric acid is accompanied by the formation of thiyl radicals, which in turn cause the isomerization of the cis fatty acid residues to the trans isomers. The relationship between methionine modification and lipid damage and some details of the reductive radical stress obtained by proteomic analysis of irradiated RNase A are presented.

Oxidative stress in Helicobacter pylori-induced gastric cell injury

Oxygen radicals are supposed to be involved in inflammation and cell proliferation. Helicobacter pylori induces decrease in antioxidant defense factors, such as GSH, mucus and constitutive nitric oxide (NO), gastric mucosal injury and inflammation. Inflammation and injury might be caused by oxidant-mediated expression of inflammatory cytokine interleukin-8 (IL-8) and inflammatory enzymes such as cyclooxtgenase-2 (COX-2) and inducible nitric oxide synthase (iNOS), which were mediated by oxidant-sensitive transcription factors such as nuclear factor-kappaB (NF-kappaB) and activator protein-1 (AP-1), possibly with mitogen activated protein kinase (MAPK) activation. H. pylori-induced alterations in protein expression demonstrate the involvement of oxidative stress in the pathogenesis of H. pylori-induced gastric diseases. The differentially expressed genes and proteins may be useful as prognostic indices for gastric diseases associated with H. pylori infection. In conclusion, oxygen radicals are produced in gastric epithelial cells infected with H. pylori, which may reduce the antioxidant defense mechanism and turn on the expression of inflammatory genes, adhesion molecules and mediators stimulating cell proliferation, as well as defensive molecular chaperones in gastric epithelial cells.

Expression of cytokeratins in Helicobacter pylori –associated chronic gastritis of adult patients infected with cagA+ strains: An immunohistochemical study

AIM: To investigate the expression of different cytokeratins (CKs) in gastric epithelium of adult patients with chronic gastritis infected with Helicobacter pylori (H pylori) cagA+ strains.

METHODS: The expression of CK 7, 8, 18, 19 and 20 was studied immunohistochemically in antral gastric biopsies of 84 patients. All the CKs were immunostained in cagA+H pylori gastritis (57 cases), non-H pylori gastritis (17 cases) and normal gastric mucosa (10 cases).

RESULTS: In cagA+ H pylori gastritis, CK8 was expressed comparably to the normal antral mucosa from surface epithelium to deep glands. Distribution of CK18 and CK 19 was unchanged, i.e. transmucosal, but intensity of the expression was different in foveolar region in comparison to normal gastric mucosa. Cytokeratin 18 immunoreactivity was significantly higher in the foveolar epithelium of H pylori-positive gastritis compared to both H pylori-negative gastritis and controls. On the contrary, decrease in CK19 immunoreactivity occurred in foveolar epithelium of H pylori-positive gastritis. In both normal and inflamed antral mucosa without H pylori infection, CK20 was expressed strongly/moderately and homogenously in surface epithelium and upper foveolar region, but in H pylori -induced gastritis significant decrease of expression in foveolar region was noted. Generally, in both normal antral mucosa and H pylori-negative gastritis, expression of CK7 was not observed, while in about half cagA+ H pylori-infected patients, moderate focal CK7 immunoreactivity of the neck and coiled gland areas was registered, especially in areas with more severe inflammatory infiltrate.

CONCLUSION: Alterations in expression of CK 7, 18, 19 and 20 together with normal expression of CK8 occur in antral mucosa of H pylori-associated chronic gastritis in adult patients infected with cagA+ strains. Alterations in different cytokeratins expression might contribute to weakening of epithelial tight junctions observed in H pylori-infected gastric mucosa.

Helicobacter pylori infection and gastric cancer

The pathogenesis of gastric cancer (GC) includes a sequence of events that begins with Helicobacter pylori-induced chronic superficial gastritis, progressing towards atrophic gastritis, intestinal metaplasia, dysplasia and eventually GC. The association between H. pylori and GC is supported by experimental data showing a capacity of H. pylori to induce GC in animals, and the results of interventional studies showing that H. pylori eradication can lower the risk of GC and prevent development of pre-cancerous lesions in humans and in experimental animals. The "driving force" of gastric carcinogenesis is a chronic gastric inflammation, whose intensity and localisation depending on bacterial, host and environmental factors, determines the risk of GC. The mechanisms by which chronic inflammation lead to epithelial and pre-cancerous lesions include induction of oxidative stress, perturbation of the epithelial cells proliferation/apoptosis ratio, and cytokine secretion. Several molecular alterations associated with gastric carcinogenesis have also been described.

Gene expression and protein profiling of AGS gastric epithelial cells upon infection with Helicobacter pylori

Helicobacter pylori, one of the most common bacterial pathogens, colonizes the human stomach and causes a variety of gastric diseases. This pathogen elicits a range of phenotypic responses in infected cultured AGS gastric epithelial cells, including expression of proinflammatory genes and changes in the actin cytoskeleton. Some of these responses are mediated by the type IV secretion system (T4SS) encoded by the cag pathogenicity island. We have used two global approaches, namely 2-DE combined with PMF and cDNA expression array analyses, to study in both a comprehensive and quantitative manner the protein profile and the temporal patterns of mRNA accumulation in AGS cells upon infection with H. pylori and isogenic T4SS mutants. We identified 140 transcripts and detected 190 protein species that were differentially regulated upon infection. Infection with wild-type H. pylori induced expression of a variety of host genes and changes in protein pattern involved in transcriptional responses, cell shape regulation and signal transduction. Among them, some were differentially regulated in a cag PAI-dependent manner, as shown by both the proteomic and cDNA expression array approaches. While 2-DE and PMF allowed us to examine the protein profiles in the infected host, array analysis enabled us to demonstrate dynamic temporal changes in host gene expression profile. In conclusion, our combined application of the two global approaches provides further molecular details on how the host cell responds to infection by H. pylori and its isogenic T4SS mutants on both transcriptional and protein levels. The findings pinpoint host proteins such as serine/threonine and tyrosine kinases, transcription factors, cell cycle related components and actin cytoskeletal signaling molecules as potential targets of individual H. pylori virulence determinants. This study serves as a basis for future work on transcription and proteome analyses of the H. pylori infection model.

Proteomic analysis of proteins expressed by Helicobacter pylori under oxidative stress

Helicobacter pylori is a spiral, slow growing gram-negative microaerophilic bacterium. It has been shown to be the etiological agent of gastroduodenal diseases, such as chronic gastritis, gastric and duodenal ulcers, and gastric cancer. To address the influence of oxidative stress and its underlying mechanisms, we have compared proliferation, urease activity and protein expression profile of H. pylori incubated under normal microaerophilic (5% O2) and aerobic stress (20% O2) conditions. Oxidative-stress cells displayed coccoid morphology and time-dependent decrease in proliferation. The urease activity was completely abrogated after 32 h. We have further compared the protein expression profiles of H. pylori under normal growing and oxidative-stress conditions by a global proteomic analysis, which includes high-resolution 2-DE followed by MALDI-TOF-MS and bioinformatic databases search/peptide-mass comparison. The results revealed that more than ten proteins were differentially expressed under oxidative stress. Most notably, the protein expression levels of urease accessory protein E (UreE, an essential metallochaperone for urease activity) and alkylhydroperoxide reductase (AhpC) with antioxidant potential are greatly decreased under stress conditions. Measurements of messenger RNA transcription level by performing RT-PCR on total mRNA also confirmed that gene expressions for these two proteins are consistently repressed under oxygen tension. These changes form a firm basis to account for the loss of urease activity and anti-oxidative ability of H. pylori after long-term exposure to reactive oxygen. Conceivably, UreE and AhpC may thus be listed as potential targets for the development of therapeutic drugs against H. pylori.

The roles of vitamin C in Helicobacter pylori associated gastric carcinogenesis

Ascorbic acid, as one of the important water-soluble vitamins, is essential for a range of physiological functions, including the syntheses of collagen, carnitine and neurotransmitters. It is also an important dietary antioxidant against oxidative stress. Current information suggests that vitamin C might be protective against the development of gastric cancer. Chronic infection with Helicobacter pylori is recognized to be a significant cause of gastric adenocarcinoma. Inflammation induced by H. pylori infection in the stomach not only causes significantly enhanced consumption of vitamin C, but also reduces secretion of the vitamin into the gastric lumen. Most of the evidence relating to vitamin C and H. pylori infection derives from clinical studies and experiments directly examining the effect of vitamin C on H. pylori-associated gastric carcinogenesis and remains limited. Furthermore, results from recent studies suggest that vitamin C might also increase the risk of cancer through its pro-oxidant activity and protect against oxidative stress in cancer cells through its antioxidant action. In this article we review recent publications on vitamin C research and assess the potential roles of vitamin C in H. pylori associated gastric carcinogenesis. The possible adverse effects of the vitamin C are also discussed.