Epigenetic alterations due to diet and Helicobacter pylori infection in gastric carcinogenesis

The Role of Methionine Restriction in Gastric Cancer: A Summary of Mechanisms and a Discussion on Tumor Heterogeneity

Gastric cancer is ranked as the fifth most prevalent cancer globally and has long been a topic of passionate discussion among numerous individuals. However, the incidence of gastric cancer in society has not decreased, but instead has shown a gradual increase in recent years. For more than a decade, the treatment effect of gastric cancer has not been significantly improved. This is attributed to the heterogeneity of cancer, which makes popular targeted therapies ineffective. Methionine is an essential amino acid, and many studies have shown that it is involved in the development of gastric cancer. Our study aimed to review the literature on methionine and gastric cancer, describing its mechanism of action to show that tumor heterogeneity in gastric cancer does not hinder the effectiveness of methionine-restricted therapies. This research also aimed to provide insight into the inhibition of gastric cancer through metabolic reprogramming with methionine-restricted therapies, thereby demonstrating their potential as adjuvant treatments for gastric cancer.

Helicobacter pylori-associated Chronic Atrophic Gastritis and Progression of Gastric Carcinogenesis

Chronic inflammation due to a Helicobacter pylori (H. pylori) infection is a representative cause of gastric cancer that can promote gastric carcinogenesis by abnormally activating immune cells and increasing the inflammatory cytokines levels. H. pylori infections directly cause DNA double-strand breaks in gastric epithelial cells and genetic damage by increasing the enzymatic activity of cytidine deaminase. Eventually, gastric cancer is induced through dysplasia. Hypermethylation of tumor suppressor genes is an important cause of gastric cancer because of a H. pylori infection. In addition, the changes in gastric microbiota and the mucosal inflammatory changes associated with a co-infection with the Epstein-Barr virus are associated with gastric cancer development. DNA damage induced by H. pylori and the subsequent responses of gastric stem cells have implications for gastric carcinogenesis. Although the pathogenesis of H. pylori has been established, many uncertainties remain, requiring more study.

Effect of Helicobacter pylori Eradication on Epigenetic Changes in Gastric Cancer-related Genes

It is known that gastric carcinogenesis results from the progressive changes from chronic gastritis to gastric atrophy, intestinal metaplasia, dysplasia, and invasive carcinoma. Several genetic and epigenetic alterations are involved in this process, and Helicobacter pylori (H. pylori) infection is believed to induce the initiation and progression of these steps. From an epigenetic point of view, H. pylori induces hypermethylation of genes involved in the development of gastric cancer and regulates the expression of various microRNAs (miRNAs). These H. pylori-related epigenetic changes are accumulated not only at the site of neoplasm but also in the adjacent non-cancerous gastric mucosa. Thereby, a state vulnerable to gastric cancer known as an epigenetic field defect is formed. H. pylori eradication can have an effective chemopreventive effect in gastric carcinogenesis. However, the molecular biological changes that occur in the stomach environment during H. pylori eradication have not yet been established. Several studies have reported that H. pylori eradication can restore infection-related changes, especially epigenetic alterations in gastric cancer-related genes, but some studies have shown otherwise. Simply put, it appears that the recovery of methylated gastric cancer-related genes and miRNAs during H. pylori eradication may vary among genes and may also differ depending on the histological subtype of the gastric mucosa. In this review, we will discuss the potential mechanism of gastric cancer prevention by H. pylori eradication, mainly from an epigenetic perspective.

Transcriptome profiling implicated in beneficiary actions of kimchi extracts against Helicobacter pylori infection

Dietary intervention to prevent Helicobacter pylori (H. pylori)-gastric cancer might be ideal because of no risk of bacterial resistance, safety, and rejuvenating action of atrophic gastritis. We have published data about the potential of fermented kimchi as nutritional approach for H. pylori. Hence recent advances in RNAseq analysis lead us to investigate the transcriptome analysis to explain these beneficiary actions of kimchi. gastric cells were infected with either H. pylori or H. pylori plus kimchi. 943 genes were identified as significantly increased or decreased genes according to H. pylori infection and 68 genes as significantly changed between H. pylori infection and H. pylori plus kimchi (p<0.05). Gene classification and Medline database showed DLL4, FGF18, PTPRN, SLC7A11, CHAC1, FGF21, ASAN, CTH, and CREBRF were identified as significantly increased after H. pylori, but significantly decreased with kimchi and NEO1, CLDN8, KLRG1, and IGFBP1 were identified as significantly decreased after H. pylori, but increased with kimchi. After KEGG and STRING-GO analysis, oxidative stress, ER stress, cell adhesion, and apoptosis genes were up-regulated with H. pylori infection but down-regulated with kimchi, whereas tissue regeneration, cellular anti-oxidative response, and anti-inflammation genes were reversely regulated with kimchi (p<0.01). Conclusively, transcriptomes of H. pylori plus kimchi showed significant biological actions.

Helicobacter pylori co-infection with Epstein-Barr virus and the risk of developing gastric adenocarcinoma at an early age: Observational study infectious agents and cancer

Background

Gastric cancer (GC) is one of the leading causes of morbidity and mortality worldwide. The onset and progression of gastric cancer are attributed to numerous triggers, these triggers may be infection of the gastric epithelium by Helicobacter pylori (H. pylori), or by Epstein-Barr virus (EBV). Both agents can establish a lifelong persistent infection in the host, leading to chronic inflammation, which also contributes to cancer development. Objective: The objective of this study is to present the status of co-infection with H. pylori and EBV and the risk of developing adenocarcinoma at an early age in the population of Grand Casablanca.

Methods

In this study, 100 gastric tissue samples from patients with gastric cancer were examined for detection of H. pylori and EBV in tumor tissue using PCR techniques, and the clinical relevance was statistically analyzed.

Results

Results revealed an individual Epstein-Barr virus (EBV) infection observed in (40 %) of gastric carcinoma cases. Furthermore, the frequency of EBV infection was significantly different with intestinal and diffuse gastric cancer types [15 % vs. 85 %; <0.05]. The prevalence of individual H. pylori infections was 34 %, while the frequency of co-infection was 16 %. Moreover, no significant association was found between co-infection and sex, tumor grade, stage, and lymph node metastasis, but there was a significant association between co-infection and the age of GC patients.

Conclusion

Thus understanding the status of co-infection could clarify the process of gastric carcinogenesis, and application of this knowledge for clinical purposes could facilitate diagnosis, risk management, and prevention.

Determination of the frequency of H. pylori and EBV infections

Correlation between co-infection and age of gastric cancer patients

Evaluation of the clinicopathological features associated with the presence of infectious agents.

Effect of Helicobacter pylori Infection on GATA-5 and TFF1 Regulation, Comparison Between Pediatric and Adult Patients

BACKGROUND

GATA factors, which constitute a family of transcription regulatory proteins, participate in gastrointestinal development. Trefoil factor 1 (TFF1) plays a crucial role in mucosal defense and healing, and evidence suggests that GATA-5 mediated its regulation. Gastric cancer is a multiple-step process triggered by Helicobacter pylori and is characterized by accumulation of molecular and epigenetic alteration. The aim of this study was to evaluate the effect of H. pylori infection on the regulation of GATA-5 and TFF1 in vitro and in vivo.

RESULTS

Infected cells exhibited upregulation of GATA-5 and TFF1 after 48 h. An increase in GATA-5 and TFF1 mRNA levels was also found in mice samples after 6 and 12 months of infection, respectively. In human samples, we found an association between H. pylori infection and GATA-5 upregulation. In fact, among H. pylori-infected patients, hypermethylation was observed in 45.5% of pediatric samples, in 62.6% of chronic gastritis samples, and in 63% of gastric cancer samples. Regarding TFF1, the expression levels were similar in pediatrics and adults patients, and were independent of H. pylori infection, and the expression of these factors was downregulated in gastric cancer samples. GATA-5 promoter methylation was associated with a decrease in TFF1 mRNA levels.

CONCLUSIONS

Our results suggest that the upregulation of GATA-5 and TFF1 observed in vitro and in vivo may be correlated with a protective effect of the mucosa in response to infection. The epigenetic inactivation of GATA-5 observed in human biopsies from infected patients may suggest that this alteration is an early event occurring in association with H. pylori infection.

DNA methyltransferases and gastric cancer: insight into targeted therapy

Gastric cancer is a major health problem worldwide occupying most frequent causes of cancer-related mortality. In addition to genetic modifications, epigenetic alterations catalyzed by DNA methyltransferases (DNMTs) are a well-characterized epigenetic hallmark in gastric cancer. The reversible nature of epigenetic alterations and central role of DNA methylation in diverse biological processes provides an opportunity for using DNMT inhibitors to enhance the efficacy of chemotherapeutics. In this review, we discussed key factors or mechanisms such as SNPs, infections and genetic modifications that trigger DNMTs level modification in gastric cancer, and their potential roles in cancer progression. Finally, we focused on how inhibitors of the DNMTs can most effectively be used for the treatment of gastric cancer with multidrug resistance.

Molecular Signaling in Tumorigenesis of Gastric Cancer

Gastric cancer (GC) is regarded as the fifth most common cancer and the third cause of cancer-related deaths worldwide. Mechanism of GC pathogenesis is still unclear and relies on multiple factors, including environmental and genetic characteristics. One of the most important environmental factors of GC occurrence is infection with Helicobacter pylori that is classified as class one carcinogens. Dysregulation of several genes and pathways play an essential role during gastric carcinogenesis. Dysregulation of developmental pathways such as Wnt/β-catenin signaling, Hedgehog signaling, Hippo pathway, Notch signaling, nuclear factor-kB, and epidermal growth factor receptor have been found in GC. Epithelial-mesenchymal transition, as an important process during embryogenesis and tumorigenesis, is supposed to play a role in initiation, invasion, metastasis, and progression of GC. Although surgery is the main therapeutic modality of the disease, the understanding of biological processes of cell signaling pathways may help to develop new therapeutic targets for GC.

NFATc3 mediates the sensitivity of gastric cancer cells to arsenic sulfide

Arsenic sulfide (As4S4) is the main component of Realgar which is widely used in traditional Chinese medicine. Previously we showed that As4S4 inhibited the proliferation of colon cancer cells through regulating nuclear factor of activated T cells (NFAT) pathway. Here we explore the role of NFAT in gastric cancer. We showed that As4S4 inhibited the expression of NFATc1, NFATc3, and NFATc4, and modulated the expression of NFATc2 accompanying with p53. The baseline expression of NFATc3 varied distinctly in gastric cancer cell lines (AGS, MGC803, MKN28, MKN45, and SGC7901) and the sensitivity of these cells to As4S4 was dissimilar, with AGS and MGC803 cells showing higher sensitivity while the SGC7901 cells relatively resistant. Interestingly, the sensitivity to As4S4 was correlated with the level of expression of NFATc3, and the cells relatively sensitivity just showing higher expression of NFATc3. Furthermore, NFATc3 expression was significantly higher in gastric cancer tissues compared with the adjacent normal tissues. Our data also showed that, NFATc3 promoted the proliferation of gastric cancer cells by regulating c-Myc. In conclusion, As4S4 inhibited the proliferation of gastric cancer cells through NFATc3/c-Myc pathway and the diverse sensitivity among different cell lines correlated with the expression level of NFATc3 indicating that NFATc3 may be a potential therapeutic target in gastric cancer.

Helicobacter pylori Induces Hypermethylation of CpG Islands Through Upregulation of DNA Methyltransferase: Possible Involvement of Reactive Oxygen/Nitrogen Species

Helicobacter pylori infection has been considered to be one of the major factors implicated in etiology of gastric cancer. Aberrant DNA methylation accounts for epigenetic modifications induced by H. pylori. H. pylori-induced hypermethylation has been linked to enhancement of the rates of metastasis and recurrence in gastric cancer patients. H. pylori-induced gene hypermethylation has been known to be associated with inflammation. However, the molecular mechanisms underlying H. pylori-induced hypermethylation remain largely unknown. This review highlights possible involvement of reactive oxygen/nitrogen species in H. pylori-induced hypermethylation and gastric carcinogenesis.

Association among lifestyle, clinical examination, polymorphisms in CDH1 gene and Traditional Chinese Medicine syndrome differentiation of gastric cancer

OBJECTIVE

To explore the association among life-style, clinical examination, polymorphisms in CDH1 gene and Traditional Chinese Medicine (TCM) syndrome differentiation of gastric cancer (GC).

METHODS

A hospital-based population of 387 GC patients was investigated in Jiangsu province. Relevant information regarding lifestyle and clinical examination were collected by a standard questionnaire. Four known single nucleotide polymorphisms (SNPs) in CDH1 were investigated by polymerase chain reaction-ligation detection reaction methods. Statistical analysis was conducted by SPSS 16.0 software.

RESULTS

The results showed that meal duration and the status of glutamic pyruvic transaminase were significantly associated with TCM syndrome differentiation of GC (both P < 0.05). None of the four SNPs in the E-cadherin (CDH1) gene achieved significant differences in their distributions among the nine syndrome types of GC (both P > 0.05). However, significant differences were observed in rs13689 genotype distributions between several pairs of syndrome types of GC, suggesting that rs13689 is correlated with the syndrome differentiation of GC.

CONCLUSION

Integrated analysis of lifestyle, clinical examination and CDH1 gene polymorphisms can contribute to a better understanding of the GC syndrome types and may improve the efficacy of interventions by stratifying disease according to TCM criteria.

RASAL1 influences the proliferation and invasion of gastric cancer cells by regulating the RAS/ERK signaling pathway

The aim of this study was to investigate the biological characteristics of the RASAL1 gene in a well-differentiated gastric cancer cell line MKN-28 and a poorly differentiated gastric cancer cell line BGC-823 cells, using RNA interference and gene transfection technology, respectively. MKN-28 cells were transfected with the shRNA of RASAL1 and BGC-823 cells were transfected with the pcDNA 3.1 plasmid vector containing RASAL1. RT-PCR and western blotting were then used to detect the expression of RASAL1 mRNA and protein. The activities of RAS and extracellular signal-regulated kinase 1/2 were analyzed by the pull-down method and western blotting. The proliferate capacity, apoptosis rate, invasive and migratory potentials of MKN-28 or BGC-823 cells were also measured by Cell Counting Kit-8 cell proliferation assay, propidium iodide/Annexin V staining coupled with flow cytometry, and transwell chamber assays, respectively. Measurement of RASAL1 mRNA and protein expression in two cells revealed successful transfection of the shRNA of RASAL1 and RASAL1-pcDNA3.1 plasmid into these two cells. Moreover, decreased expression of RASAL1 in MKN-28 cells resulted in increased expression of RAS-GTP and p-ERK1/2. Interestingly, decreased expression of RASAL1 inhibited apoptosis and facilitated cell proliferation, invasion and migration. The increased expression of RASAL1 in BGC-823 cells caused declined expression of RAS-GTP and p-ERK1/2, as well as promoted apoptosis and restrained cell proliferation, invasion and migration. The down-regulation of RASAL1 promoted the proliferation, invasion and migration of gastric cancer MKN-28 cells, and up-regulation of RASAL1 inhibited the proliferation, invasion and migration of BGC-823 gastric cancer cells by regulating the RAS/ERK signaling pathway. Thus, our results suggest that RASAL1 may play an important role as a tumor suppressor gene in gastric cancer.

Gastric juice microRNA-421 is a new biomarker for screening gastric cancer

MicroRNA-421 (miR-421) plays crucial roles during carcinogenesis and is a potential tumor marker in the diagnosis of several types of cancers. However, whether miR-421 in gastric juice, which is specific for gastric tissue, can be used as a biomarker for gastric cancer screening is unclear. In the present study, real-time quantitative reverse transcription-polymerase chain reaction was used to analyze miR-421 levels in gastric juice from patients with gastric cancer or benign gastric disease, or normal. A receiver operating characteristic (ROC) curve was constructed to evaluate the diagnostic values. The results showed that gastric juice levels of miR-421 in patients with gastric cancer were significantly different from those in benign gastric diseases (P < 0.001). The area under the ROC curve of miR-421 was up to 0.767 (95 % CI = 0.684-0.850). The levels of miR-421 in gastric juice from gastric patients were not significantly associated with the main clinicopathological factors such as tumor size, Lauren's classification, and Borrmann's classification. For the detection of early gastric cancer, the use of gastric juice miR-421 showed a remarkable improvement compared with the use of serum carcinoembryonic antigen alone. These results indicated that gastric juice miRNAs such as miR-421 are useful biomarkers for screening gastric cancer.

Honey and apoptosis in human gastric mucosa

BACKGROUND

Gastric cancer is the fourth most common malignancy in the world. Honey is a complex mixture of special biological active constituents. Honey possesses antioxidant and antitumor properties. Nutritional studies have indicated that consumption of honey modulates the risk of developing gastric cancer. On the other hand, apoptosis has been reported to play a decisive role in precancerous changes. Our chief study was conducted to assess the relationship between consumption of honey and apoptosis in human gastric mucosa.

METHOD

This cross-sectional study was conducted on 98 subjects over 18 years old, referred to two hospitals in Tabriz, Iran. Subjects were undergone an upper gastrointestinal endoscopy, 62 subjects were finally enrolled. Honey consumption was assessed by a Food Frequency Questionnaire (FFQ) and apoptosis was detected by TUNEL technique. We tested polynomial curve to find the best fit between honey consumption and apoptosis.

RESULTS

A positive relation between honey consumption and apoptosis was found (P=0.024). Our results indicated that the final and the best fit curve was: apoptosis = 1.714+1.648(honey amount) - 0.533(honey amount)2 +1.833×10-5(honey amount)7.

CONCLUSION

Honey consumption had positive effects on gastric cancer by inducing apoptosis in gastric mucosa.

Clinical potential of DNA methylation in gastric cancer: a meta-analysis

BACKGROUND

Accumulating evidence indicates aberrant DNA methylation is involved in gastric tumourigenesis, suggesting it may be a useful clinical biomarker for the disease. The aim of this study was to consolidate and summarize published data on the potential of methylation in gastric cancer (GC) risk prediction, prognostication and prediction of treatment response.

METHODS

Relevant studies were identified from PubMed using a systematic search approach. Results were summarized by meta-analysis. Mantel-Haenszel odds ratios were computed for each methylation event assuming the random-effects model.

RESULTS

A review of 589 retrieved publications identified 415 relevant articles, including 143 case-control studies on gene methylation of 142 individual genes in GC clinical samples. A total of 77 genes were significantly differentially methylated between tumour and normal gastric tissue from GC subjects, of which data on 62 was derived from single studies. Methylation of 15, 4 and 7 genes in normal gastric tissue, plasma and serum respectively was significantly different in frequency between GC and non-cancer subjects. A prognostic significance was reported for 18 genes and predictive significance was reported for p16 methylation, although many inconsistent findings were also observed. No bias due to assay, use of fixed tissue or CpG sites analysed was detected, however a slight bias towards publication of positive findings was observed.

CONCLUSIONS

DNA methylation is a promising biomarker for GC risk prediction and prognostication. Further focused validation of candidate methylation markers in independent cohorts is required to develop its clinical potential.

A genetic variation in APE1 is associated with gastric cancer survival in a Chinese population

Altered DNA repair can be associated with aggressive tumor biology and impact on survival of cancer patients. We investigated whether genetic variation of human apurinic/apyrimidinic (AP) endonuclease, a key multifunctional gene involved in the base excision repair pathway, would play a role in gastric cancer survival outcomes. We genotyped APE1 rs1760944 by the TaqMan method in 925 gastric cancer patients. Analyses of association between the polymorphism and survival outcomes were carried out using the Kaplan-Meier method, Cox proportional hazards models, and the log-rank test. Survival analyses for all patients showed that the differences in median survival time between gastric cancer carriers with APE1 rs1760944 TT (55 months) and those with GT/GG (78 months), were statistically significant (P = 0.025, log-rank test). Kaplan-Meier survival estimates revealed that gastric cancer patients carrying the GT/GG genotypes had a higher survival than TT, and this protective effect was also more pronounced among subgroups with tumor size >5 cm (hazard ratio = 0.66, 95% confidence interval = 0.49-0.88), diffuse-type gastric cancer (0.76, 0.60-0.97), T3 depth of invasion (0.73, 0.57-0.93), lymph node metastasis (0.73, 0.58-0.92), no distant metastasis (0.81, 0.66-0.99), and TNM stage III and IV (0.75, 0.58-0.99 for stage III; 0.50, 0.29-0.88 for stage IV). Our results showed that the genetic variant rs1760944 in APE1 was associated with gastric cancer survival in a Chinese population. Larger studies are needed to verify our findings in different populations.

Lineage-specific promoter DNA methylation patterns segregate adult progenitor cell types

Mesenchymal stem cells (MSCs) can differentiate into multiple mesodermal cell types in vitro; however, their differentiation capacity is influenced by their tissue of origin. To what extent epigenetic information on promoters of lineage-specification genes in human progenitors influences transcriptional activation and differentiation potential remains unclear. We produced bisulfite sequencing maps of DNA methylation in adipogenic, myogenic, and endothelial promoters in relation to gene expression and differentiation capacity, and unravel a similarity in DNA methylation profiles between MSCs isolated from human adipose tissue, bone marrow (BM), and muscle. This similarity is irrespective of promoter CpG content. Methylation patterns of MSCs are distinct from those of hematopoietic progenitor cells (HPCs), pluripotent human embryonic stem cells (hESCs), and multipotent hESC-derived mesenchymal cells (MCs). Moreover, in vitro MSC differentiation does not affect lineage-specific promoter methylation states, arguing that these methylation patterns in differentiated cells are already established at the progenitor stage. Further, we find a correlation between lineage-specific promoter hypermethylation and lack of differentiation capacity toward that lineage, but no relationship between weak promoter methylation and capacity of transcriptional activation or differentiation. Thus, only part of the restriction in differentiation capacity of tissue-specific stem cells is programmed by promoter DNA methylation: hypermethylation seems to constitute a barrier to differentiation, however, no or weak methylation has no predictive value for differentiation potential.

Dietary reference values of individual micronutrients and nutriomes for genome damage prevention: current status and a road map to the future

Damage to the genome is recognized as a fundamental cause of developmental and degenerative diseases. Several micronutrients play an important role in protecting against DNA damage events generated through endogenous and exogenous factors by acting as cofactors or substrates for enzymes that detoxify genotoxins as well as enzymes involved in DNA repair, methylation, and synthesis. In addition, it is evident that either micronutrient deficiency or micronutrient excess can modify genome stability and that these effects may also depend on nutrient-nutrient and nutrient-gene interaction, which is affected by genotype. These observations have led to the emerging science of genome health nutrigenomics, which is based on the principle that DNA damage is a fundamental cause of disease that can be diagnosed and nutritionally prevented on an individual, genetic subgroup, or population basis. In this article, the following topics are discussed: 1) biomarkers used to study genome damage in humans and their validation, 2) evidence for the association of genome damage with developmental and degenerative disease, 3) current knowledge of micronutrients required for the maintenance of genome stability in humans, 4) the effect of nutrient-nutrient and nutrient-genotype interaction on DNA damage, and 5) strategies to determine dietary reference values of single micronutrients and micronutrient combinations (nutriomes) on the basis of DNA damage prevention. This article also identifies important knowledge gaps and future research directions required to shed light on these issues. The ultimate goal is to match the nutriome to the genome to optimize genome maintenance and to prevent pathologic amounts of DNA damage.

H. pylori-induced promoter hypermethylation downregulates USF1 and USF2 transcription factor gene expression

Helicobacter pylori infection is associated with the development of gastric adenocarcinoma. Upstream stimulatory factors USF1 and USF2 regulate the transcription of genes related to immune response, cell cycle and cell proliferation. A decrease in their expression is observed in human gastric epithelial cells infected with H. pylori, associated to a lower binding to their DNA E-box recognition site as shown by electrophoretic mobility shift assay. DNA methylation leads to gene silencing. The treatment of cells with 5'-azacytidine, an inhibitor of DNA methylation, restored the USF1 and USF2 gene expression in the presence of infection. Using promoter PCR methylation assay, a DNA hypermethylation was shown in the promoter region of USF1 and USF2 genes, in infected cells. The inhibition of USF1 and USF2 expression by H. pylori and the DNA hypermethylation in their gene promoter region was confirmed in gastric tissues isolated from 12 to 18 months infected mice. Our study demonstrated the involvement of USF1 and USF2 as molecular targets of H. pylori and the key role of DNA methylation in their regulation. These mechanisms occurred in the context of metaplastic lesions, suggesting that alteration of USF1 and USF2 levels could participate in the promotion of neoplastic process during H. pylori infection.

Up-regulation of Nrf2-mediated heme oxygenase-1 expression by eckol, a phlorotannin compound, through activation of Erk and PI3K/Akt

The aim of the present study was to examine the cytoprotective effect of eckol, a phlorotannin found in Ecklonia cava and to elucidate underlying mechanisms. Heme oxygenase-1 (HO-1) is an important antioxidant enzyme that plays a role in cytoprotection against oxidative stress. Eckol-induced HO-1 expression both at the level of mRNA and protein in Chinese hamster lung fibroblast (V79-4) cells, resulting in increased HO-1 activity. The transcription factor NF-E2-related factor 2 (Nrf2) is a critical regulator of HO-1, achieved by binding to the antioxidant response element (ARE). Eckol treatment resulted in the enhanced level of phosphorylated form, nuclear translocation, ARE-binding, and transcriptional activity of Nrf2. Extracellular regulated kinase (Erk) and phosphatidylinositol 3-kinase (PI3K)/protein kinase B (PKB, Akt) contributed to ARE-driven HO-1 expression. Eckol activated both Erk and Akt, and treatments with U0126 (an Erk kinase inhibitor), LY294002 (a PI3K inhibitor), specific Erk1 siRNA, and Akt siRNA suppressed the eckol-induced activation of Nrf2, resulting in a decrease in HO-1 expression. ZnPP (a HO-1 inhibitor), HO-1 siRNA, and Nrf2 siRNA markedly abolished the cytoprotective effect of eckol against hydrogen peroxide-induced cell damage. Likewise, U0126 and LY294002 inhibited the eckol-induced cytoprotective effect against oxidative cell damage. These studies demonstrate that eckol attenuates oxidative stress by activating Nrf2-mediated HO-1 induction via Erk and PI3K/Akt signaling.

Polymorphisms of TGFB1 and VEGF genes and survival of patients with gastric cancer

Background

Some TGFB1 and VEGF polymorphisms are believed to be functional. Given that these genes are involved in tumor growth and progression including angiogenesis, dissemination, and invasiveness, we hypothesized that these polymorphisms would be associated with survival in patients with gastric cancer.

Methods

We genotyped TGFB1 -509 C>T, +1869 T>C, and +915 G>C and VEGF -1498T>C, -634G>C, and +936C>T in 167 patients with gastric cancer. Using the Kaplan and Meier method, log-rank tests, and Cox proportional hazard models, we evaluated associations among TGFB1 and VEGF variants with overall, 1-year, and 2-year survival rates.

Results

Although there were no significant differences in overall survival rates among all polymorphisms tested, patients with TGFB1+915CG and CC genotypes had a poorer 2-year survival (adjusted hazard ratio (HR), 3.06; 95% confidence interval (CI), 1.09–8.62; P = 0.034) than patients with the GG genotype had. In addition, patients heterozygous for VEGF -634CG also had a poorer 1-year survival (adjusted HR, 2.08; 95% CI, 1.03–4.22; P = 0.042) than patients with the -634GG genotype.

Conclusion

Our study suggested that TGFB1+915CG/CC and VEGF -634CG genotypes may be associated with short-term survival in gastric cancer patients. However, larger studies are needed to verify these findings.