Role In Gastric Carcinogenesis Research Articles

Gastrin May Mediate the Carcinogenic Effect of Helicobacter pylori Infection of the Stomach.

Gastric cancer occurs almost exclusively in patients with gastritis. Since Helicobacter pylori (Hp) was proved to cause gastritis, Hp was also expected to play a role in gastric carcinogenesis. Despite extensive studies, the mechanisms by which Hp cause gastric cancer are still poorly understood. However, there is evidence that the anatomical site of Hp infection is of major importance. Infection confined to the antral mucosa protects against gastric cancer but predisposes to duodenal ulcer, whereas Hp infection of the oxyntic mucosa increases the risk of gastric cancer. Hp infection does not predispose to cancers in the gastric cardia. In patients with atrophic gastritis of the oxyntic mucosa, the intragastric pH is elevated and the concentration of microorganisms in the stomach is increased. This does not lead to increased risk of gastric cancer at all anatomical sites. The site specificity of Hp infection in relation to cancer risk indicates that neither Hp nor the changes in gastric microflora due to gastric hypoacidity are carcinogenic per se. However, reduced gastric acidity also leads to hypergastrinemia, which stimulates the function and proliferation of enterochromaffin-like (ECL) cells located in the oxyntic mucosa. The ECL cell may be more important in human gastric carcinogenesis than previously realized, as every condition causing long-term hypergastrinemia in animals results in the development of neoplasia in the oxyntic mucosa. Patients with hypergastrinemia will far more often develop carcinomas in the gastric corpus. In conclusion, hypergastrinemia may explain the carcinogenic effect of Hp.

Claudin-1 enhances tumor proliferation and metastasis by regulating cell anoikis in gastric cancer.

Claudin-1 (CLDN1) is overexpressed in gastric cancer and correlated with tumor invasion, metastasis and poor outcome. Here, we both down and up regulated CLDN1 expression in gastric cancer cells to elucidate its role in gastric carcinogenesis and tumor progression. We found that deficiency of CLDN1 inhibited cells migration, invasion, and colony formation in vitro and tumorigenicity, metastasis in vivo. Also, CLDN1 promoted cell aggregation and increased anoikis resistance. Down or up regulation of CLDN1 was accompanied with changes of membrane β-catenin expression as well as Akt and Src activities. When β-catenin was up-regulated in CLDN1-KD cells, cell aggregation and anoikis resistance were restored, and Akt and Src signal pathways were re-activated. Taken together, these findings suggest that CLDN1 is oncogenic in gastric cancer and its malignant potential may be attributed in part to regulation of anoikis, by mediating membrane β-catenin-regulated cell-cell adhesion and cell survival.

Abstract 5261: Aberrant expression of HDAC6 sustains malignant progression by preventing epidermal growth factor receptor degradation in gastric cancer

Abstract Cytoplasmic deacetylase, histone deacetylase 6 (HDAC6) is a critical component of the lysomal protein degradation pathways. HDAC6 has been shown to be involved in carcinogenic transformation and to modulate the epithelial-mesenchymal transition in several cancers by way of the regulations of several critical cellular functions, but the biological roles in gastric carcinogenesis remains to be elucidated. In this study, we observed that HDAC6 is aberrantly over-expressed in a subset of gastric cancer, and that targeted-inactivation of HDC6 caused cell cycle and cell death pathways-independent growth inhibition. Additional experiments evidenced that ectopic overexpression of HDAC6 sustains epidermal growth factor receptor (EGFR) degradation in EGF-stimulated gastric cancer cells. In addition, we found that HDAC6 inactivation recovered rabaptin 5, a Rab5 interacting protein potentiating Rab5, a small GTPase that regulates early endocytic events. These findings suggest that aberrant overexpression of HDAC6 confers gastric cancer cells to sustain EGF-signaling by retardation of EGFR degradation by way of repression of rababtin-5, and HDAC6 is a bona fide target for therapeutic intervention in gastric cancers. Note: This abstract was not presented at the meeting. Citation Format: Se Jin Park, Hyun Jin Bae, Jung Woo Eun, Qinngyu Shen, Hyung Seok Kim, Woo Chan Shin, Won Sang Park, Jung Young Lee, Suk Woo Nam. Aberrant expression of HDAC6 sustains malignant progression by preventing epidermal growth factor receptor degradation in gastric cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5261. doi:10.1158/1538-7445.AM2014-5261

The impact of Helicobacter pylori on EGF, EGF receptor, and the c-erb-B2 expression

PurposeIncreased expression of epidermal growth factor (EGF), its receptor (EGFR), and c-erb-B2 protein, which is homological with the EGF receptor, in gastric mucosa, may play a role in gastric carcinogenesis. We assessed if the infection and eradication of Helicobacter pylori (H. pylori) affects the gastric expression of growth factors and serum gastrin concentrations. Patients/methodsWe examined immunohistochemically gastric EGF and both receptors’ expression in: gastric cancer (GC; n=29), chronic gastritis with H. pylori infection (GHp+; n=40) before and after eradication and in patients without H. pylori infection (GHp−; n=42). ResultsBefore the eradication therapy, gastric mucosal EGF and both receptor's expressions in GHp+ patients were increased compared to GHp− (p<0.05), but were similar to GC. After eradication, EGF and the receptor's expression significantly decreased in the gastric body. Both EGFR and c-erb-B2 expression in the antrum were still higher than in GHp− (p<0.05), and remained comparable to GC. ConclusionsIn patients with H. pylori infection the gastric mucosal EGF, EGFR, and c-erb-B2 expressions are similar to those observed in gastric cancer. The persistence of the antral expression of receptors after eradication, at a level comparable to the gastric cancer group, suggests their eventual role in the progression of changes initiated by H. pylori toward carcinogenesis.

Tu1658 Inhibition of Peritoneal Metastasis by Overcoming Death Receptor Resistance by Small Molecule Targeting of C-FLIP

Background: Helicobacter pylori (H.pylori) infection plays an important role in gastric carcinogenesis and exemplifies the strong association between inflammation and cancer. DARPP-32 (Dopamine and cAMP-regulated phosphoprotein, Mr 32000) is a novel cancer gene. The aim of this study was to investigate the role of inflammation and H.pylori in regulating DARPP-32 expression. Methods: Immunohistochemistry (IHC) were used to determine protein expression. DARPP-32 promoter activity was measured by a luciferase reporter system. The mRNA and protein levels were evaluated by quantitative real-time PCR and Western blot analysis. Results: The IHC analysis demonstrated overexpression of p-NFκB and DARPP-32 in the early stages of human gastric cancer. Therefore, we examined the relationship between NF-kB and DARPP-32, and found that DARPP-32 does not regulate the transcriptional activity of NF-κB as measured by pNF-κB luciferase reporter and western blot analysis. On the other hand, we found that TNF-α treatment leads to activation of NFκB and mediates upregulation of mRNA and protein levels of DARPP-32 in several gastric cancer cell lines (P 10-fold, P<0.001) and protein levels. In addition, treatment with an NF-κB inhibitor (BAY 11-7082) decreased DARPP-32 mRNA and protein levels. In an attempt to study the transcriptional regulation, we cloned a 2500 bp of the DARPP-32 promoter into the luciferase reporter (DARPP-32-Luc). The TNF-α treatment of AGS and MKN-45 cells led to a significant induction of luciferase activity of DARPP-32 reporter (P<0.01), and treatment of these cells with BAY 11-7082 (5 μM) reversed these effects (P<0.01). Furthermore, transient expression of NF-kB-p65 in AGS cells led to a 3fold induction in the luciferase activity of DARPP-32 reporter (P<0.01). Using deletion constructs, we have found that the -1000bp of promoter area is the most active region. We confirmed that NF-kB-p65 binds to DARPP-32 promoter by ChIP assay. In vitro data using gastric cancer cell lines and H.pylori infection (J166 and 7.13 strains) demonstrated simultaneous increase in the p-NF-kB and increase in the mRNA and protein levels of DARPP-32. Using the Tff1-KO gastric cancer mouse model that is characterized by NF-kB activation, we found that DARPP-32 was overexpressed at the protein and mRNA levels. Treatment of wild-type and Tff1-KO mice with H.pylori (PMSS1 strain) led to significant induction of both p-NF-kB and DARPP-32. Conclusion: Our results demonstrated, for the first time, that H. pylori infection leads to induction of NF-κB-dependent DARPP-32 expression. Given the oncogenic functions of DARPP-32 in regulating the PI3K/AKT and CXCR4 signaling, this novel DARPP-32 regulationmechanism provides a new paradigm in gastric carcinogenesis.

Tu1654 Pro-Inflammatory Signaling Transcriptional Regulates DARPP-32 in Gastric Cancer

Background: Helicobacter pylori (H.pylori) infection plays an important role in gastric carcinogenesis and exemplifies the strong association between inflammation and cancer. DARPP-32 (Dopamine and cAMP-regulated phosphoprotein, Mr 32000) is a novel cancer gene. The aim of this study was to investigate the role of inflammation and H.pylori in regulating DARPP-32 expression. Methods: Immunohistochemistry (IHC) were used to determine protein expression. DARPP-32 promoter activity was measured by a luciferase reporter system. The mRNA and protein levels were evaluated by quantitative real-time PCR and Western blot analysis. Results: The IHC analysis demonstrated overexpression of p-NFκB and DARPP-32 in the early stages of human gastric cancer. Therefore, we examined the relationship between NF-kB and DARPP-32, and found that DARPP-32 does not regulate the transcriptional activity of NF-κB as measured by pNF-κB luciferase reporter and western blot analysis. On the other hand, we found that TNF-α treatment leads to activation of NFκB and mediates upregulation of mRNA and protein levels of DARPP-32 in several gastric cancer cell lines (P 10-fold, P<0.001) and protein levels. In addition, treatment with an NF-κB inhibitor (BAY 11-7082) decreased DARPP-32 mRNA and protein levels. In an attempt to study the transcriptional regulation, we cloned a 2500 bp of the DARPP-32 promoter into the luciferase reporter (DARPP-32-Luc). The TNF-α treatment of AGS and MKN-45 cells led to a significant induction of luciferase activity of DARPP-32 reporter (P<0.01), and treatment of these cells with BAY 11-7082 (5 μM) reversed these effects (P<0.01). Furthermore, transient expression of NF-kB-p65 in AGS cells led to a 3fold induction in the luciferase activity of DARPP-32 reporter (P<0.01). Using deletion constructs, we have found that the -1000bp of promoter area is the most active region. We confirmed that NF-kB-p65 binds to DARPP-32 promoter by ChIP assay. In vitro data using gastric cancer cell lines and H.pylori infection (J166 and 7.13 strains) demonstrated simultaneous increase in the p-NF-kB and increase in the mRNA and protein levels of DARPP-32. Using the Tff1-KO gastric cancer mouse model that is characterized by NF-kB activation, we found that DARPP-32 was overexpressed at the protein and mRNA levels. Treatment of wild-type and Tff1-KO mice with H.pylori (PMSS1 strain) led to significant induction of both p-NF-kB and DARPP-32. Conclusion: Our results demonstrated, for the first time, that H. pylori infection leads to induction of NF-κB-dependent DARPP-32 expression. Given the oncogenic functions of DARPP-32 in regulating the PI3K/AKT and CXCR4 signaling, this novel DARPP-32 regulationmechanism provides a new paradigm in gastric carcinogenesis.

Differential expression of histone deacetylase and acetyltransferase genes in gastric cancer and their modulation by trichostatin A

Gastric cancer is still the second leading cause of cancer-related death worldwide, even though its incidence and mortality have declined over the recent few decades. Epigenetic control using histone deacetylase inhibitors, such as trichostatin A (TSA), is a promising cancer therapy. This study aimed to assess the messenger RNA (mRNA) levels of three histone deacetylases (HDAC1, HDAC2, and HDAC3), two histone acetyltransferases (GCN5 and PCAF), and two possible targets of these histone modifiers (MYC and CDKN1A) in 50 matched pairs of gastric tumors and corresponding adjacent nontumors samples from patients with gastric adenocarcinoma, as well as their correlations and their possible associations with clinicopathological features. Additionally, we evaluated whether these genes are sensitive to TSA in gastric cancer cell lines. Our results demonstrated downregulation of HDAC1, PCAF, and CDKN1A in gastric tumors compared with adjacent nontumors (P < 0.05). On the other hand, upregulation of HDAC2, GCN5, and MYC was observed in gastric tumors compared with adjacent nontumors (P < 0.05). The mRNA level of MYC was correlated to HDAC3 and GCN5 (P < 0.05), whereas CDKN1A was correlated to HDAC1 and GCN5 (P < 0.05 and P < 0.01, respectively). In addition, the reduced expression of PCAF was associated with intestinal-type gastric cancer (P = 0.03) and TNM stages I/II (P = 0.01). The increased expression of GCN5 was associated with advanced stage gastric cancer (P = 0.02) and tumor invasion (P = 0.03). The gastric cell lines treated with TSA showed different patterns of histone deacetylase and acetyltransferase mRNA expression, downregulation of MYC, and upregulation of CDKN1A. Our findings suggest that alteration of histone modifier genes play an important role in gastric carcinogenesis, contributing to MYC and CDKN1A deregulation. In addition, all genes studied here are modulated by TSA, although this modulation appears to be dependent of the genetic background of the cell line.

RETRACTED ARTICLE: Role of p16 gene promoter methylation in gastric carcinogenesis: a meta-analysis

This meta-analysis was performed to evaluate the relationships between promoter DNA methylation in tumor suppressor gene p16 and gastric carcinogenesis. The PubMed, CISCOM, CINAHL, Web of Science, Google Scholar, EBSCO, Cochrane Library and CBM databases were searched for relevant articles published before November 1st, 2013 without any language restrictions. Meta-analysis was conducted using the STATA 12.0 software. Crude odds ratios (ORs) with 95% confidence intervals (95% CI) were calculated. Forty-seven clinical cohort studies that met all inclusion criteria were included in this meta-analysis. A total of 2,813 gastric cancer (GC) patients were assessed. Our meta-analysis results revealed that the frequencies of p16 promoter methylation in the GC tissues were higher than those of normal and adjacent tissues (Normal: OR = 23.04, 95% CI = 13.55-39.15, P < 0.001; Adjacent: OR = 4.42, 95% CI = 1.66-11.76, P = 0.003; respectively). Furthermore, we observed significant associations of p16 promoter methylation with TNM stage, histologic grade, invasive grade, lymph node metastasis of GC (TNM stage: OR = 3.60, 95% CI: 2.17-5.98, P < 0.001; Histologic grade: OR = 2.63, 95% CI: 1.55-4.45, P < 0.001; Invasive grade: OR = 3.44, 95% CI: 1.68-7.06, P = 0.001; Lymph node metastasis: OR = 2.68, 95% CI: 1.66-4.32, P < 0.001; respectively). However, there were no correlations of p16 promoter methylation with the TNM stage and Helicobacter pylori (HP) infection of GC (Tumor size: OR = 0.76, 95% CI: 0.14-4.07, P = 0.746; HP infection: OR = 1.31, 95% CI: 0.75-2.27, P = 0.342; respectively). Our findings provide empirical evidence that p16 promoter methylation may play an important role in gastric carcinogenesis. Thus, p16 promoter methylation may be a promising potential biomarker for the early diagnosis of GC.

Increased expression of IL17A in human gastric cancer and its potential roles in gastric carcinogenesis

Inflammatory cytokines modulate immune responses in the tumor microenvironment during progression. The role of interleukin (IL) 17A in cancer is currently under debate. We aim to investigate the expression of IL17A in situ tumors as well as in nontumor gastric mucosa tissues and further explore the functional significance of IL17A on gastric cancer cells in vitro. We found that compared with nontumor regions, the expression of IL17A were increased significantly in tumors of gastric cancer patients (P=0.007). The immunoreactivity for IL17A was found only in cytoplasm of inflammatory cells as well as vascular endothelial cells but not in tumor cells. Consistently, IL17A transcription was silenced in a variety of gastric cancer cell lines. In vitro, recombinant human IL17A protein promotes cell proliferation and monolayer wound healing of both AGS and SGC7901cells, in a dose-dependent manner. Besides, IL17A inhibits H2O2-induced cell apoptosis. Expression of IL6 and MMP13 mRNA was increased significantly after IL17A stimulation. These data suggest that accumulation of intratumoral IL17A-producing cells may promote gastric cancer progression directly or by inducing key signal transduction pathways implicated in gastric carcinogenesis.

Deregulated expression of Nucleophosmin 1 in gastric cancer and its clinicopathological implications

BackgroundThe process of gastric carcinogenesis still remains to be elucidated. The identification of genes related to this process may help to reduce mortality rates through early diagnosis and the development of new anticancer therapies. Nucleophosmin 1 (NPM1) acts in ribosome biogenesis, centrosome duplication, maintenance of genomic stability, and embryonic development. Recently, NPM1 has been implicated in the tumorigenesis processes. Here, we evaluated NPM1 gene and protein expression in gastric tumors and in corresponding non-neoplastic gastric samples.MethodsNPM1 protein expression was determined by Western blot in 17 pairs of gastric tumors and corresponding non-neoplastic gastric tissue. The protein immunoreactivity was observed in 12 tumor samples. mRNA expression was evaluated by reverse transcription quantitative polymerase chain reaction (RT-qPCR) in 22 pairs of gastric tumors and in matched non-neoplastic gastric tissue.ResultsNPM1 protein expression was significantly reduced in gastric cancer samples compared to matched non-neoplastic gastric samples (P = 0.019). The protein level of NPM1 was reduced at least 1.5-fold in 35% of tumors compared to paired non-neoplastic gastric tissue. However, NPM1 immunoreactivity was detected in neoplastic and non-neoplastic cells, including in intestinal metaplastic, gastritis and inflammatory cells. NPM1 was mainly expressed in nucleus and nucleolus subcellular compartments. The staining intensity and the percentage of immunoreactive cells varied among the studied cases. The NPM1 mRNA level was reduced at least 1.5-fold in 45.5% of samples and increased in 27.3% of samples. An inverse correlation between protein and mRNA expression was detected (r = -0.509, P = 0.037). Intestinal-type gastric cancer presented higher mRNA levels than diffuse-type (P = 0.026). However, reduced NPM1 protein expression was associated with intestinal-type gastric cancer compared to matched non-neoplastic gastric samples (P = 0.018). In addition, tumors from patients with known distant metastasis presented reduced NPM1 protein levels compared to tumors from patients without distant metastasis (P < 0.001).ConclusionAlthough the expression of NPM1 is heterogeneous in gastric tumors, our results suggest that NPM1 down-regulation may have a role in gastric carcinogenesis and may help in the selection of anticancer treatment strategies.

DNA methylation in gastric cancer, related toHelicobacter pyloriand Epstein-Barr virus

Gastric cancer is a leading cause of cancer death worldwide, and significant effort has been focused on clarifying the pathology of gastric cancer. In particular, the development of genome-wide analysis tools has enabled the detection of genetic and epigenetic alterations in gastric cancer; for example, aberrant DNA methylation in gene promoter regions is thought to play a crucial role in gastric carcinogenesis. The etiological viewpoint is also essential for the study of gastric cancers, and two distinct pathogens, Helicobacter pylori (H. pylori) and Epstein-Barr virus (EBV), are known to participate in gastric carcinogenesis. Chronic inflammation of the gastric epithelium due to H. pylori infection induces aberrant polyclonal methylation that may lead to an increased risk of gastric cancer. In addition, EBV infection is known to cause extensive methylation, and EBV-positive gastric cancers display a high methylation epigenotype, in which aberrant methylation extends to not only Polycomb repressive complex (PRC)-target genes in embryonic stem cells but also non-PRC-target genes. Here, we review aberrant DNA methylation in gastric cancer and the association between methylation and infection with H. pylori and EBV.

Efficacy ofHelicobacter pylorieradication for the prevention of metachronous gastric cancer after endoscopic resection for early gastric cancer

Helicobacter pylori (H. pylori) plays an important role in gastric carcinogenesis, as the majority of gastric cancers develop from H. pylori-infected gastric mucosa. The rate of early gastric cancer diagnosis has increased in Japan and Korea, where H. pylori infection and gastric cancer are highly prevalent. Early intestinal-type gastric cancer without concomitant lymph node metastasis is usually treated by endoscopic resection. Secondary metachronous gastric cancers often develop because atrophic mucosa left untreated after endoscopic treatment confers a high risk of gastric cancer. The efficacy of H. pylori eradication for the prevention of metachronous gastric cancer remains controversial. However, in patients who undergo endoscopic resection of early gastric cancer, H. pylori eradication is recommended to suppress or delay metachronous gastric cancer. Careful and regularly scheduled endoscopy should be performed to detect minute metachronous gastric cancer after endoscopic resection.

DNA methyltransferase3a expression is an independent poor prognostic indicator in gastric cancer.

To explore the alteration of DNA methyltransferase expression in gastric cancer and to assess its prognostic value. From April 2000 to December 2010, 227 men and 73 women with gastric cancer were enrolled in the study. The expression of DNA methyltransferases (DNMTs), including DNMT1, DNMT3a and DNMT3b, in the 300 cases of gastric carcinoma, of which 85 had paired adjacent normal gastric mucus samples, was evaluated by immunohistochemistry using a tissue microarray. Serum anti-Helicobacter pylori (H. pylori) IgG was detected by enzyme-linked immunosorbent assay (ELISA). The relationships between the above results and the clinicopathological characteristics were analyzed. Their prognostic value was evaluated using the Cox proportional hazards model. In gastric cancer, expression of DNMTs was mainly seen in the nucleus. Weak staining was also observed in the cytoplasm. Expression of DNMT1, DNMT3a and DNMT3b in gastric cancer was significantly higher compared to that in the paired control samples (60.0% vs 37.6%, 61.2% vs 4.7%, and 94.1% vs 71.8%, P < 0.01). The overall survival rate was significantly higher in the DNMT3a negative group than in the DNMT3a positive group in gastric cancer patients (Log-rank test, P = 0.032). No significant correlation was observed between DNMT1 and DNMT3b expression and the overall survival time (Log-rank test, P = 0.289, P = 0.347). Multivariate regression analysis indicated that DNMT3a expression (P = 0.025) and TNM stage (P < 0.001), but not DNMT1 (P = 0.54) or DNMT3b (P = 0.62), were independent prognostic factors in gastric cancer. H. pylori infection did not induce protein expression of DNMTs. The results suggest that expression of DNMT3a is an independent poor prognostic indicator in gastric cancer. DNMT3a might play an important role in gastric carcinogenesis.

Common genetic variants at 1q22 and 10q23 and gastric cancer susceptibility in a Korean population

Genetic variants at 1q22 and 10q23 were identified as genetic markers of both gastric cancer and esophageal squamous cell carcinoma susceptibility by two genome-wide association studies. The aim of this study was to determine whether rs4072037A > G in MUC1 at 1q22 and rs2274223A > G in PLCE1 at 10q23 are associated with a risk of gastric cancer in a Korean population. We conducted a large-scale case-control study of 3,245 patients with gastric cancer and 1,700 controls. The allele frequencies of rs4072037G and rs2274223G were 11.2 and 25.5% among patients with gastric cancer, compared with 12.8 and 26.4%, respectively, among controls. We found that the rs4072037 AG genotype was significantly associated with a reduced risk of gastric cancer [odds ratios (OR) = 0.78; 95% confidence interval (CI) = 0.67-0.91 for AG vs AA]. Compared with the rs2274223 AA genotype, we found a significant association between the rs2274223 AG genotype and a weakly reduced risk of gastric cancer (OR = 0.87; 95% CI = 0.76-0.99 for AG vs AA). Our data suggest that genetic variants at 1q22 and 10q23 play a role in gastric carcinogenesis.

MicroRNA‐212 inhibits proliferation of gastric cancer by directly repressing retinoblastoma binding protein 2

Retinoblastoma binding protein 2 (RBP2), a newly found histone demethylase, is overexpressed in gastric cancer. We examined the upstream regulatory mechanism of RBP2 at the microRNA (miRNA) level and the role in gastric carcinogenesis. We used bioinformatics to predict that microRNA-212 (miR-212) might be a direct upstream regulator of RBP2 and verified the regulation in gastric epithelial-derived cell lines. Overexpression of miR-212 significantly inhibited the expression levels of RBP2, whereas knockdown of miR-212 promoted RBP2 expression. Furthermore, we identified the putative miR-212 targeting sequence in the RBP2 3' UTR by luciferase assay. MiR-212 inhibited the colony formation ability of cells by repressing RBP2 expression and increasing that of P21(CIP1) and P27(kip1), both critical in cell cycle arrest. In addition, the expression of RBP2 and miR-212 in tumor tissue and matched normal tissue from 18 patients further supported the results in vivo. MiR-212 directly regulates the expression of RBP2 and inhibits cell growth in gastric cancer, which may provide new clues to treatment.

Inducible nitric oxide synthase expression in gastric adenocarcinoma: impact on lymphangiogenesis and lymphatic metastasis

BackgroundLymphatic metastasis is the most important parameter in the spread of gastric carcinomas. Nitric oxide (NO) is a signaling molecule that plays an important role in inflammation and carcinogenesis. In this study, the possible link between inducible nitric oxide synthase (iNOS) expression with lymphangiogenesis and the clinicopathological parameters of gastric carcinomas was investigated.MethodsIn this study, iNOS expression and D2-40 (lymphatic endothelium-specific marker monoclonal antibody) reactivity were examined immunohistochemically in 41 gastric adenocarcinoma and 20 non-neoplastic gastric tissues. iNOS expression was scored semiquantitatively in the tumor parenchyma and stroma. D2-40-positive lymphatic vessels were used in the determination of lymphatic invasion and intratumoral and peritumoral lymphatic vascular density.ResultsiNOS expression was higher in gastric carcinoma tissue compared with non-neoplastic tissue. Particularly, iNOS expression in tumor cells was found to be closely related to lymphangiogenesis and lymphatic metastasis. The density of lymphatic invasion as well as intratumoral and peritumoral lymphatic vascular density were positively correlated with lymph node metastasis.ConclusionsOur results suggest that iNOS-mediated NO formation plays an important role in gastric carcinogenesis, tumor lymphangiogenesis, and the development of lymphatic metastases. Inhibition of the NO pathway may be an alternative treatment of gastric carcinomas.Virtual slidesThe virtual slides for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1713572940104388.

TLR9 Promoter Polymorphism Is Associated with Both an Increased Susceptibility to Gastric Carcinoma and Poor Prognosis

ObjectiveGenetic polymorphisms of Toll-like receptors (TLRs) may influence the effects of H. pylori infection and play important roles in gastric carcinogenesis. The aim of this study was to determine whether the polymorphisms of TLR4 and TLR9 are associated with susceptibility to gastric carcinoma and its prognosis.MethodsThis study consisted of 314 patients with gastric cancer and 314 healthy controls. The polymorphisms were assessed using polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP) analysis. Survival was analyzed by Kaplan–Meier survival curves.ResultsNo variant genotypes of TLR4+896A/G, TLR4+1196C/T, or TLR9 -1237T/C were detected. For TLR9 -1486 T/C, multiple logistic regression analyses revealed that compared with the TT homozygote, patients with both the TC variant (adjusted odds ratio (OR) = 1.47, 95% confidence interval (CI) = 1.04–2.10) and the CC variant (adjusted OR = 1.63, 95% CI = 1.01–2.64) had higher risks of gastric cancer. Further stratification analyses revealed that an increased risk of gastric cancer associated with C carriers was evident among females (adjusted OR = 1.84, 95%CI = 1.02–3.33), in younger subjects aged less than 60 years old (adjusted OR = 1.86, 95%CI = 1.15–3.00), and subjects with H. pylori infection (adjusted OR = 1.53, 95% CI = 1.03–2.27). We also observed a significant association between C carriers and noncardia gastric cancer (adjusted OR = 1.51, 95% CI = 1.03–2.20). In addition, we demonstrated that the C carrier genotype and H. pylori infection may have a synergistic effect and conferred an OR of 2.44 for developing gastric cancer. TLR9 -1486C was also identified as an independent marker of poor survival of carcinoma.ConclusionsOur results suggest that TLR9 -1486C carriers are associated with an increased risk and poor prognosis of gastric carcinoma in the Chinese population.

Helicobacter pylori infection and antioxidants can modulate the genotoxic effects of heterocyclic amines in gastric mucosa cells

Helicobacter pylori (H. pylori) infection plays an important role in gastric carcinogenesis. This bacterium may induce cancer transformation and change the susceptibility of gastric mucosa cells to various exogenous dietary irritants. The aim of the study was to evaluate the influence of H. pylori infection on the reaction of the stomach cells to a genotoxic effect of heterocyclic amines (HCAs). These well-known mutagens are formed during cooking of protein-rich foods, primarily meat. Taking into account that persons consuming a mixed-western diet are exposed to these compound nearly an entire lifetime and more than half of human population is infected with H. pylori, it is important to assess the combined effect of H. pylori infection and HCAs in the context of DNA damage in gastric mucosa cells, which is a prerequisite to cancer transformation. We employed 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), 2-amino-3,8-dimethyl-imidazo[4,5-f]quinoxaline (MeIQx) and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) because these substances are present in a great amount in cooked and fried meat. Using alkaline comet assay, we showed that the extent of the DNA damage induced by HCAs was significantly higher in H. pylori infected gastric mucosa cells than in non-infected counterparts. We did not observed any difference in the efficiency of repair of DNA lesions induced by HCAs in both type of cells. Vitamin C reduced the genotoxic effects of HCAs in H. pylori infected and non-infected gastric mucosa cells. Melatonin more effectively decreased DNA damage caused by HCAs in H. pylori infected gastric mucosa cells as compared with control. Our results suggest that H. pylori infection may influence the susceptibility of gastric mucosa cells to HCAs and dietary antioxidative substances, including vitamin C and melatonin may inhibit the genotoxic effects of HCAs on gastric mucosa cells and may reduce the risk of carcinogenesis caused by food borne mutagens and H. pylori infection.

Su1982 Favorable Prognostic Factors in Advanced Gastric Cancer Patients Ineligible for Criteria of the Clinical Trial

Background/Aims: According to Correa's hypothesis, adenoma at stomach plays a role in gastric carcinogenesis as a precursor. Since endoscopic resection including endoscopic submucosal dissection for premaligant or cancerous lesion has been generally accepted as one of treatment options, endoscopist may have a chance to get the pathologic results showing early gastric cancer arising from adenoma (EGC-AFA). However there have been few reports about clinicopathologic characteristics of EGC-AFA. The aim of this study was to evaluate characteristics of EGC-AFA compared to de novo EGC treated by endoscopic resection. Methods: Between January 2008 and December 2011, 1005 EGCs form 981 S-524 AGA Abstracts patients by endoscopic resectionwere enrolled.We retrospectively reviewed clinicopathologic data of 1005 EGC lesions. Among them 161 lesions (16%) were EGC-AFA and 844 (84%) were de novo EGC. Results: There was no significant difference of age, sex, location of tumor, and gross morphology on EGD between two groups. Synchronous cancer was significantly more frequent in EGC-AFA than in de novo EGC (19.3% vs 10.3%, p=0.001). The tumor size of EGC-AFA measured on EGD was significantly larger than that of de novo EGC (16.6±9.9mm vs 14.5±7.3mm, p=0.004). However, there was no significant difference of actual tumor size on pathologic specimen. The frequency of pathologic discrepancy between biopsy specimen and resected one was higher in EGC-AFA than in de novo EGC (36.6% vs 24.2%, p=0.01). In pathologic characteristics, the differentiated type adenocarcinoma has been shown more frequent in EGC-AFA than de novo EGC (95% vs 88%, p= 0.009), and the submucosal invasion according to T stage (T1b) was significantly less frequent in EGC-AFA than in de novo EGC (12.4% vs 18.0%, p=0.001). Conclusion: The observation of co-existence of adenoma and carcinoma in one specimen is not uncommon. Due to association of adenomatous changes around cancerous lesion, misdiagnosis rate at biopy specimen higher in EGC-AFA and the size measurement of EGC-AFA might be exaggerated on EGD examination. The features of more differentiation and less invasiveness would give more favorable prognosis to EGC-AFA. The endoscopist should pay attention on synchronous ormetachronous lesions on follow up endoscopic examinationwhen encountered EGC-AFA.

Su1983 Pepsinogen I/II Ratio Is Superior to Pepsinogen I and II and Gastrin 17 in the Diagnosis of Atrophic Gastritis

Background/Aims: According to Correa's hypothesis, adenoma at stomach plays a role in gastric carcinogenesis as a precursor. Since endoscopic resection including endoscopic submucosal dissection for premaligant or cancerous lesion has been generally accepted as one of treatment options, endoscopist may have a chance to get the pathologic results showing early gastric cancer arising from adenoma (EGC-AFA). However there have been few reports about clinicopathologic characteristics of EGC-AFA. The aim of this study was to evaluate characteristics of EGC-AFA compared to de novo EGC treated by endoscopic resection. Methods: Between January 2008 and December 2011, 1005 EGCs form 981 S-524 AGA Abstracts patients by endoscopic resectionwere enrolled.We retrospectively reviewed clinicopathologic data of 1005 EGC lesions. Among them 161 lesions (16%) were EGC-AFA and 844 (84%) were de novo EGC. Results: There was no significant difference of age, sex, location of tumor, and gross morphology on EGD between two groups. Synchronous cancer was significantly more frequent in EGC-AFA than in de novo EGC (19.3% vs 10.3%, p=0.001). The tumor size of EGC-AFA measured on EGD was significantly larger than that of de novo EGC (16.6±9.9mm vs 14.5±7.3mm, p=0.004). However, there was no significant difference of actual tumor size on pathologic specimen. The frequency of pathologic discrepancy between biopsy specimen and resected one was higher in EGC-AFA than in de novo EGC (36.6% vs 24.2%, p=0.01). In pathologic characteristics, the differentiated type adenocarcinoma has been shown more frequent in EGC-AFA than de novo EGC (95% vs 88%, p= 0.009), and the submucosal invasion according to T stage (T1b) was significantly less frequent in EGC-AFA than in de novo EGC (12.4% vs 18.0%, p=0.001). Conclusion: The observation of co-existence of adenoma and carcinoma in one specimen is not uncommon. Due to association of adenomatous changes around cancerous lesion, misdiagnosis rate at biopy specimen higher in EGC-AFA and the size measurement of EGC-AFA might be exaggerated on EGD examination. The features of more differentiation and less invasiveness would give more favorable prognosis to EGC-AFA. The endoscopist should pay attention on synchronous ormetachronous lesions on follow up endoscopic examinationwhen encountered EGC-AFA.