LST-2, a human liver-specific organic anion transporter, determines methotrexate sensitivity in gastrointestinal cancers

BACKGROUND & AIMS

One approach to the development of targeted cancer chemotherapy exploits increased uptake of the agent into neoplastic cells. In this scenario, higher concentrations of the agent in cancer cells are responsible for differential killing, whereas the low concentration in normal human cells decreases side effects. The aim of this study was to isolate an organic anion transporter that is weak in normal cells, but abundantly expressed in cancer cells, to deliver the anticancer drugs to the cells.

METHODS

A human liver complementary DNA (cDNA) library was screened with liver-specific transporter (LST)-1 cDNA as a probe. Northern blot analyses were performed using the isolated cDNA (termed LST-2). An LST-2-specific antibody was raised, and immunohistochemical analyses including immunoelectron microscopy were performed. Xenopus oocyte expression system was used for functional analysis. We also established a permanent cell line that consistently expresses LST-2 to examine the relationship between methotrexate uptake and sensitivity.

RESULTS

The isolated cDNA, LST-2, has 79.7% of overall homology with human LST-1. LST-2 exclusively expressed in the liver under normal conditions and its immunoreactivity was highest at the basolateral membrane of the hepatocytes around the central vein. Although its weak expression in the liver, LST-2 is abundantly expressed in the gastric, colon, and pancreatic cancers. On the other hand, the LST-1 was only detected in a hepatic cell line. LST-2 transports methotrexate in a saturable and dose-dependent manner. Furthermore, introduction of the LST-2 gene into mammalian cells potentiates sensitivity to methotrexate.

CONCLUSIONS

LST-2 is one of the prime candidate molecules for determining methotrexate sensitivity and may be a good target to deliver anticancer drugs to the gastrointestinal cancers.

NOD1 contributes to mouse host defense against Helicobacter pylori via induction of type I IFN and activation of the ISGF3 signaling pathway

Nucleotide-binding oligomerization domain 1 (NOD1) is an intracellular epithelial cell protein known to play a role in host defense at mucosal surfaces. Here we show that a ligand specific for NOD1, a peptide derived from peptidoglycan, initiates an unexpected signaling pathway in human epithelial cell lines that results in the production of type I IFN. Detailed analysis revealed the components of the signaling pathway. NOD1 binding to its ligand triggered activation of the serine-threonine kinase RICK, which was then able to bind TNF receptor-associated factor 3 (TRAF3). This in turn led to activation of TANK-binding kinase 1 (TBK1) and IkappaB kinase epsilon (IKKepsilon) and the subsequent activation of IFN regulatory factor 7 (IRF7). IRF7 induced IFN-beta production, which led to activation of a heterotrimeric transcription factor complex known as IFN-stimulated gene factor 3 (ISGF3) and the subsequent production of CXCL10 and additional type I IFN. In vivo studies showed that mice lacking the receptor for IFN-beta or subjected to gene silencing of the ISGF3 component Stat1 exhibited decreased CXCL10 responses and increased susceptibility to Helicobacter pylori infection, phenotypes observed in NOD1-deficient mice. These studies thus establish that NOD1 can activate the ISGF3 signaling pathway that is usually associated with protection against viral infection to provide mice with robust type I IFN-mediated protection from H. pylori and possibly other mucosal infections.

The polymorphism interleukin 8 -251 A/T influences the susceptibility of Helicobacter pylori related gastric diseases in the Japanese population

BACKGROUND

Helicobacter pylori infection is associated with variable clinical outcomes, including gastroduodenal diseases, and genetic factors may be relevant in this process.

AIMS

We investigated the effects of an interleukin 8 (IL-8) gene polymorphism on the risk of gastroduodenal diseases, the degree of H pylori induced gastritis, and IL-8 gene transcription.

SUBJECTS

The study was performed in 244 healthy control subjects and 690 H pylori positive patients with non-cardia gastric cancer, gastric ulcer, duodenal ulcer, or gastritis.

METHODS

We identified the IL-8 -251 A/T polymorphism by direct sequence analysis, and measured the gastritis score and serum pepsinogen (PG). The transcriptional promoter activity of the IL-8 gene was assessed by luciferase assay.

RESULTS

IL-8 -251A was associated with a higher risk of gastric cancer and gastric ulcer. Patients carrying IL-8 -251A showed an increased risk of gastric cancer (odds ratios (OR) 2.01 (95% confidence interval (CI) 1.38-2.92)) and gastric ulcer (OR 2.07 (95% CI 1.37-3.12)). Compared with patients younger than 49 years, atrophy and metaplasia scores in the antrum were significantly higher and the PG I/II ratio significantly lower in -251A carriers than in T/T carriers. In the in vitro assay, IL-8 -251A showed enhanced promoter activity in response to IL-1beta or tumour necrosis factor alpha.

CONCLUSIONS

The IL-8 -251A allele may be associated with progression of gastric atrophy in patients with H pylori infection, and may increase the risk of gastric cancer and gastric ulcer in Japanese people.

Muramyl dipeptide activation of nucleotide-binding oligomerization domain 2 protects mice from experimental colitis

The mechanisms underlying the susceptibility of individuals with caspase recruitment domain 15 (CARD15) mutations and corresponding abnormalities of nucleotide-binding oligomerization domain 2 (NOD2) protein to Crohn disease are still poorly understood. One possibility is based on previous studies showing that muramyl dipeptide (MDP) activation of NOD2 negatively regulates TLR2 responses and that absence of such regulation leads to heightened Th1 responses. We now report that administration of MDP protects mice from the development of experimental colitis by downregulating multiple TLR responses, not just TLR2. The basis of these in vivo findings was suggested by in vitro studies of DCs, in which we showed that prestimulation of cells with MDP reduces cytokine responses to multiple TLR ligands and this reduction is dependent on enhanced IFN regulatory factor 4 (IRF4) activity. Further studies of mouse models of colitis showed that this inhibitory role of IRF4 does in fact apply to MDP-mediated protection from colitis, since neither IRF4-deficient mice nor mice treated with siRNA specific for IRF4 were protected. These findings indicate that MDP activation of NOD2 regulates innate responses to intestinal microflora by downregulating multiple TLR responses and suggest that the absence of such regulation leads to increased susceptibility to Crohn disease.

Identification of thyroid hormone transporters in humans: different molecules are involved in a tissue-specific manner

We have recently identified that rat organic anion transporters, polypeptide2 (oatp2) and oatp3, both of which transport thyroid hormones. However, in humans the molecular organization of the organic anion transporters has diverged, and the responsible molecule for thyroid hormone transport has not been clarified, except for human liver-specific transporter (LST-1) identified by us. In this study we isolated and characterized a novel human organic anion transporter, OATP-E from human brain. The isolated complementary DNA encodes a polypeptide of 722 amino acids with 12 transmembrane domains. A rat counterpart, oatp-E, was also identified. Homology analysis and the phylogenetic tree analysis revealed that OATP-E/oatp-E is a subfamily of the organic anion transporter. Human OATP-E transported 3,3',5-triiodo-L-thyronine (K(m), 0.9 microM), thyronine, and rT(3) in a Na(+)-independent manner. Although the clone was isolated from the brain, OATP-E messenger RNA was abundantly expressed in various peripheral tissues. The rat counterpart, oatp-E, also transported 3,3',5-triiodo-L-thyronine. In addition, in this study we revealed that human OATP, which is exclusively expressed in the brain, transported 3,3',5-triiodo-L-thyronine (K(m), 6.5 microM), T(4) (K(m), 8.0 microM), and rT(3). These data suggest that in humans, several different molecules are involved in transporting thyroid hormone: OATP in the brain, LST-1 in the liver, and OATP-E in peripheral tissues.

Cellular and molecular mechanisms underlying NOD2 risk-associated polymorphisms in Crohn's disease

The discovery that polymorphisms in the NOD2 (nucleotide-binding oligomerization domain containing 2) gene are associated with a greatly increased risk for the development of Crohn's disease has provided a means to achieve a deeper understanding of the dysregulation of mucosal immune responses to the commensal intestinal organisms that is thought to underlie this disease. NOD2 is a NOD-like receptor (NLR) family member that senses and responds to bacterial wall peptides; thus, the most widely held view of the relation of the NOD2 polymorphisms with Crohn's disease is that these polymorphisms lead to deficient immune responses to gut bacteria, and these, in turn, lead to quantitative or qualitative changes in the bacterial population in the gut lumen or lamina propria that cause inflammation at this site. Initially, this view was based mainly on the observation that defective NOD2 function can result in reduced α-defensin production by intestinal Paneth cells and that such impairment leads to loss of host defense against gut bacteria. In this review, we reconsider this possibility and marshal evidence that it is not in fact likely to be a prime element of Crohn's disease causation. More recently, evidence has been accumulating that the NOD2 dysfunction leads to Crohn's inflammation by inducing changes in the gut microbiome that influence immune effector or regulatory function. We review the strengths and weaknesses of this emerging hypothesis. Finally, we consider the possibility that NOD2 dysfunction can lead to inflammation because of a second and somewhat overlooked aspect of its function, that as an immunoregulator of innate immune responses. In particular, we review the body of evidence that NOD2 stimulation activates a cross-tolerance response that downregulates and thus prevents excessive TLR responses that cause Crohn's inflammation.

Notch1 signaling and regulatory T cell function

Previous studies have shown that the Notch1 and TGF-beta signaling pathways are mutually re-enforcing. Given recent evidence that regulatory T cell (Treg) effector function is mediated by TGF-beta signaling, we investigated whether Notch1 signaling also participated in Treg effector function. Initial studies showed that Notch1 ligands, particularly Jagged1, are present on Tregs and that, indeed, blockade of Notch1 signaling with an anti-Jagged1 or a blocking anti-Notch1 Ab inhibits Treg suppressor function in vitro. We then showed that a signaling component generated by Notch1 activation (Notch1 intracellular domain) of dendritic cells physically interacts with a signaling component generated by TGF-beta signaling (pSmad3). Furthermore, this interaction has functional downstream effects because over-expression of Notch1 intracellular domain facilitates pSmad3 translocation to the nucleus and enhances pSmad3 transcriptional activity of a Smad-sensitive promoter linked to a luciferase reporter. Finally, we showed that blockade of TGF-beta signaling and Notch signaling did not have additive inhibitory effects on Treg suppressor function. These results are consistent with the conclusion that Notch1 signaling facilitates TGF-beta-mediated effector function of Tregs.

The molecular basis of NOD2 susceptibility mutations in Crohn's disease

Nucleotide oligomerization domain (NOD)2 is a member of the NOD-like receptor family of proteins that initiate inflammatory responses when exposed to ligands derived from bacterial components that gain access to the intracellular milieu. It is thus somewhat paradoxical that polymorphisms in the gene that encode NOD2 (CARD15) that lead to impaired NOD2 function, are susceptibility factors in Crohn's disease, a condition marked by excessive inflammatory responses to normal bacterial flora. In an initial series of studies conducted in our laboratory to better define NOD2 function and to resolve this paradox we showed that NOD2 activation by its ligand, muramyl dipeptide (MDP) ordinarily downregulates responses to Toll-like receptor (TLR) stimulation, and thus cells lacking NOD2 mount increased responses to such stimulation. This fits with the fact that mice bearing an NOD2 transgene, and thus having cells with increased NOD2 function display decreased responses to TLR stimulation and are resistant to experimental colitis induction. In further studies, we showed that prestimulation of cells with NOD2 ligand renders them unresponsive to TLR stimulation, because such prestimulation results in the elaboration of inhibitory factor (IRF4), an inhibitor of TLR-induced inflammatory pathways. Furthermore, administration of MDP to normal mice induces IRF4 and prevents experimental colitis. These studies strongly suggest that NOD2 polymorphisms are associated with Crohn's disease because they lead to a decrease in the negative regulation of TLR responses occurring in the normal gut, and thus a pathologic increase in responses to the normal flora. The finding that MDP administration prevents experimental colitis opens the door to the possibility that such treatment might quell Crohn's disease relapses in patients without NOD2 abnormalities.

NOD2 transgenic mice exhibit enhanced MDP-mediated down-regulation of TLR2 responses and resistance to colitis induction

BACKGROUND & AIMS

Mutations in the CARD15 gene encoding NOD2 are susceptibility factors in Crohn's disease. We explored the mechanism of this susceptibility using mice that over express NOD2.

METHODS

Cellular and molecular responses of mice bearing an NOD2 transgene or administered plasmids that express wild-type and mutated NOD2 constructs were examined.

RESULTS

In initial studies, we showed that splenocytes from NOD2 transgenic mice as compared with littermate controls exhibit decreased interleukin (IL)-12p70 responses to peptidoglycan (PGN), a TLR2 ligand that contains muramyl dipeptide, but not other TLR ligands; in contrast, IL-12 responses to PAM(3)CSK(4), a TLR2 ligand that does not contain muramyl dipeptide, were normal. Similarly, transgenic mice as compared with controls exhibited greatly decreased IL-12p40 responses to intraperitoneal administration of PGN but not to lipopolysaccharide. In further studies, we showed using electrophoretic mobility shift assay that PGN-stimulated cells from transgenic mice exhibited decreased activation of nuclear factor kappaB. Finally, in a series of studies on the effect of the NOD2 on susceptibility to induced colitis, we found that (1) transgenic mice were highly resistant to induction of PGN colitis and partially resistant to induction of trinitrobenzene sulfonic acid (TNBS) colitis and (2) mice administered a plasmid expressing a wild-type NOD2 gene were completely resistant to TNBS colitis whereas mice administered a plasmid expressing an NOD2 gene with the Crohn's disease frameshift mutation were only slightly resistant to TNBS colitis.

CONCLUSIONS

These data offer new evidence that NOD2 mutations contribute to inflammatory bowel disease by causing excessive TLR2 cytokine responses.

Identification and characterization of novel rat and human gonad-specific organic anion transporters

We have isolated three novel organic anion transporter cDNAs designated rat GST-1 (gonad-specific transporter), rat GST-2, and human GST, expressed at high levels in the testis. Rat GST-1, GST-2, and human GST consist of 748, 702, and 719 amino acids, respectively, and all molecules possess the 12 predicted transmembrane domains, which is a common structure of organic anion transporters. Northern blot analyses and in situ hybridization revealed that both of the rat molecules are highly expressed in the testis, especially in Sertoli cells, spermatogonia, and Leydig cells. Weak signals are also detected in the epididymis and ovary in adult rat. The exclusive expression of human GST mRNA in the testis was confirmed by RT-PCR. The pharmacological experiments of Xenopus laevis oocytes injected with the respective rat GST-1- and GST-2-cRNAs revealed that both rat GST-1 and GST-2 transport taurocholic acid, dehydroepiandrosterone sulfate, and T4 with Michaelis-Menten kinetics (taurocholic acid, Km = 8.9 and 2.5 microm, dehydroepiandrosterone sulfate, Km = 25.5 and 21.microm, and T4, Km = 6.4 and 5.8 for rat GST-1 and GST-2, respectively). T3 was also transported by rat GST-1 and GST-2. These data suggest that rat GST-1 and GST-2 might be one of the molecular entities responsible for transporting dehydroepiandrosterone sulfate and thyroid hormones involved in the regulation of sex steroid transportation and spermatogenesis in the gonad.

Molecular characterization of human and rat organic anion transporter OATP-D

We have isolated and characterized a novel human and rat organic anion transporter subtype, OATP-D. The isolated cDNA from human brain encodes a polypeptide of 710 amino acids (Mr 76,534) with 12 predicted transmembrane domains. The rat clone encodes 710 amino acids (Mr 76,821) with 97.6% amino acid sequence homology with human OATP-D. Human and rat OATP-D have moderate amino acid sequence homology with LST-l/rlst-1, the rat oatp family, the prostaglandin transporter, and moatl/MOAT1/KIAA0880/OATP-B. Phylogenetic tree analysis revealed that OATP-D is branched in a different position from all known organic anion transporters. OATP-D transports prostaglandin E1 (Km 48.5 nM), prostaglandin E2 (Km 55.5 nM), and prostaglandin F2,, suggesting that, functionally, OATP-D encodes a protein that has similar characteristics to those of the prostaglandin transporter. Rat OATP-D also transports prostaglandins. The expression pattern of OATP-D mRNA was abundant mainly in the heart, testis, brain, and some cancer cells. Immunohistochemical analysis further revealed that rat OATP-D is widely expressed in the vascular, renal, and reproductive system at the protein level. These results suggest that OATP-D plays an important role in translocating prostaglandins in specialized tissues and cells.

NOD2 downregulates colonic inflammation by IRF4-mediated inhibition of K63-linked polyubiquitination of RICK and TRAF6

It is well established that polymorphisms of the caspase activation and recruitment domain 15 (CARD15) gene, a major risk factor in Crohn's disease (CD), lead to loss of nucleotide-binding oligomerization domain 2 (NOD2) function. However, a molecular explanation of how such loss of function leads to increased susceptibility to CD has remained unclear. In a previous study exploring this question, we reported that activation of NOD2 in human dendritic cells by its ligand, muramyl dipeptide (MDP), negatively regulates Toll-like receptor (TLR)-mediated inflammatory responses. Here we show that NOD2 activation results in increased interferon regulatory factor 4 (IRF4) expression and binding to tumor necrosis factor receptor associated factor 6 (TRAF6) and RICK (receptor interacting serine-threonine kinase). We then show that such binding leads to IRF4-mediated inhibition of Lys63-linked polyubiquitination of TRAF6 and RICK and thus to downregulation of nuclear factor (NF)-κB activation. Finally, we demonstrate that protection of mice from the development of experimental colitis by MDP or IRF4 administration is accompanied by similar IRF4-mediated effects on polyubiquitination of TRAF6 and RICK in colonic lamina propria mononuclear cells. These findings thus define a mechanism of NOD2-mediated regulation of innate immune responses to intestinal microflora that could explain the relation of CARD15 polymorphisms and resultant NOD2 dysfunction to CD.

Cdx2 Expression and Intestinal Metaplasia Induced by H. pylori Infection of Gastric Cells Is Regulated by NOD1-Mediated Innate Immune Responses

Chronic infection with the bacterial Helicobacter pylori is a major cause of gastric and duodenal ulcer disease, gastric mucosal atrophy, and cancer. H. pylori-induced expression of the intestinal epithelial-specific transcription factor caudal-related homeobox 2 (Cdx2) contributes to intestinal metaplasia, a precursor event to gastric cancer. Given a role for the bacterial pattern recognition molecule nucleotide-binding oligomerization domain 1 (NOD1) in the innate immune response to bacterial infection, we investigated mechanisms used by NOD1 to regulate H. pylori infection and its propensity towards the development of intestinal metaplasia. We found that Cdx2 was induced by H. pylori infection in both normal and neoplastic gastric epithelial cells in a manner that was inversely related to NOD1 signaling. Mechanistic investigations revealed that Cdx2 induction relied upon activation of NF-κB but was suppressed by NOD1-mediated activation of TRAF3, a negative regulator of NF-κB. In vivo, prolonged infection of NOD1-deficient mice with H. pylori led to increased Cdx2 expression and intestinal metaplasia. Furthermore, gastric epithelial cells from these mice exhibited increased nuclear expression of the NF-κB p65 subunit and decreased expression of TRAF3. Overall, our findings illuminated a role for NOD1 signaling in attenuating H. pylori-induced Cdx2 expression in gastric epithelial cells, suggesting a rationale to augment NOD1 signaling in H. pylori-infected patients to limit their risks of accumulating precancerous gastric lesions.

A Japanese case series of 12 patients with esophageal eosinophilia

BACKGROUND

Eosinophilic esophagitis (EoE) has been a rarely recognized condition in Asian populations, and its clinical manifestation is rarely documented. Our aim was to describe clinically, endoscopically, and pathologically the features of patients with esophageal eosinophilia, including EoE.

METHODS

Twelve patients histologically proven to have esophageal eosinophilia were investigated. The histological diagnostic cutoff value was defined as a peak of ≥15 eosinophils/high-power field (HPF) in esophageal biopsies. Symptoms, endoscopic and pathological findings, and treatment outcome were evaluated.

RESULTS

Nine of the 12 patients were male and the 12 patients had a mean age of 47.7 years. Allergic conditions were concurrent in a total of 3 patients. Mild peripheral eosinophilia was observed in only 2 patients. The predominant symptom was solid-food dysphagia, but some patients complained of heartburn, or chest, epigastric, or back pain. Three asymptomatic subjects were also incidentally diagnosed during endoscopic screening. Linear furrows, concentric rings, and white exudates in the esophagus were frequently observed. In 4 of 5 patients who were administered a proton pump inhibitor (PPI), esophageal eosinophilia was histologically decreased or disappeared with symptom relief and endoscopic improvement. In 2 patients unresponsive to PPI, topical steroid therapy, administered by the swallowing of fluticasone propionate, led to symptomatic and histological remission.

CONCLUSIONS

The endoscopic recognition of linear furrows, concentric rings, and white exudates is important in the diagnosis of eosinophilic esophageal inflammation. In a subset of patients this condition improves clinicopathologically with PPI treatment, and typical EoE, as strictly defined by unresponsiveness to PPI, appears to be a rather rare condition.

Helicobacter pylori-negative gastric mucosa-associated lymphoid tissue lymphomas: A review

Since Isaacson and Wright first reported on the extra-nodal marginal zone B-cell lymphoma of the stomach in 1983, following studies have clarified many aspects of this disease. We now know that the stomach is the most affected organ by this disease, and approximately 90% of gastric mucosa-associated lymphoid tissue (MALT) lymphomas are related to Helicobacter pylori (H. pylori) infection. This implies that approximately 10% of gastric MALT lymphomas occur independent of H. pylori infection. The pathogenesis of these H. pylori-negative gastric MALT lymphomas remains unclear. To date, there have been several speculations. One possibility is that genetic alterations result in nuclear factor-kappa B (NF-κB) activation. Among these alterations, t(11;18)(q21;q21) is more frequently observed in H. pylori-negative gastric MALT lymphomas, and such translocation results in the synthesis of fusion protein API2-MALT1, which causes canonical and noncanonical NF-κB activation. Another possibility is infection with bacteria other than H. pylori. This could explain why H. pylori eradication therapy can cure some proportions of H. pylori-negative gastric MALT lymphoma patients, although the bacteria responsible for MALT lymphomagenesis are yet to be defined. Recent advances in endoscopy suggest magnifying endoscopy with narrow band imaging as a useful tool for both detecting gastric MALT lymphoma lesions and judging the response to treatment. A certain proportion of H. pylori-negative gastric MALT lymphoma patients respond to eradication therapy; hence, H. pylori eradication therapy could be considered as a first-line treatment for gastric MALT lymphomas regardless of their H. pylori infection status.

Gender differences in oesophageal mucosal injury in a reflux oesophagitis model of rats

OBJECTIVE

There is a strong male predominance of oesophageal adenocarcinoma, which might be related to the higher prevalence of precursor lesions such as erosive reflux oesophagitis in men compared with women. This experiment investigated the gender difference in a reflux oesophagitis model of rats and explored the potential role of oestrogen in controlling oesophageal tissue damage.

DESIGN

An acid-reflux oesophagitis model was surgically produced in male and female rats, and ascorbic acid in the diet and sodium nitrite in the drinking water were administered to half of either group to provoke luminal exogenous nitric oxide (NO) as an exacerbating agent. Seven days after the surgery, the oesophagus was excised, and the injury area, myeloperoxidase activity and pro-inflammatory cytokine levels were measured. Furthermore, 17β-oestradiol was administered to ovariectomised female rats or male rats, which then underwent reflux oesophagitis surgery.

RESULTS

While there was no gender difference in oesophageal damage in the baseline model, oesophageal damage was more intensively observed in males than in females in the presence of exogenous NO administration. While oesophageal damage was increased in ovariectomised rats compared with sham ovariectomised, exacerbated oesophageal damage was attenuated by the replacement of 17β-oestradiol. In addition, exacerbated oesophageal damage in male rats was suppressed by 17β-oestradiol.

CONCLUSION

This is the first study showing the prominent gender difference in the severity of oesophageal tissue damage in a gastro-oesophageal reflux disease-related animal model, highlighting the critical involvement of oestrogen in controlling gastro-oesophageal reflux disease-related oesophageal epithelial injury.

Helicobacter pylori induces gastric mucosal intestinal metaplasia through the inhibition of interleukin-4-mediated HMG box protein Sox2 expression

Helicobacter pylori is a major cause of the transdifferentiation into intestinal metaplasia that may develop gastric cancer. However, the molecular pathogenesis of this transdifferentiation is poorly understood. A SRY-related HMG box protein Sox2 is an essential transcription factor of organ development in brain, lung, and stomach. Our aim of this study was to investigate the mechanism responsible for regulation of Sox2 in host Th1-dominant response to H. pylori. Sox2 protein was immunohistochemically expressed in both human oxyntic and pyloric glands with H. pylori infection, but not in intestinal metaplasia. Western immunoblotting of gastric epithelial cell lines showed that IL-4, a Th2-related cytokine, dose dependently enhanced Sox2 expression among H. pylori infection-mediated cytokines. Small changes of Sox2 expression were observed after each treatment with IFN-gamma, IL-1beta, or TNF-alpha. IL-4-mediated Sox2 induction was suppressed by the inhibition of STAT6 activation with STAT6 RNA interference, and electrophoretic mobility shift assay indicated that activation of the Sox2 promoter by IL-4 occurred through the action of STAT6. Furthermore, H. pylori and IFN-gamma inhibited the phosphorylation of STAT6, resulting in the suppression of IL-4-mediated Sox2 expression. Immunohistochemical analyses showed significantly the suppressed STAT6 activity in H. pylori-infected human gastric mucosa. Additionally, downregulation of Sox2 by knockdown experiments led to intestinal phenotype with expressions of Cdx2 and MUC2. These results suggest that H. pylori and IFN-gamma interfere with the differentiation into oxyntic and pyloric glands by the downregulation of Sox2 on IL-4/STAT6 signaling, which may contribute to the transdifferentiation into intestinal metaplasia.

Low serum levels of pepsinogen and gastrin 17 are predictive of extensive gastric atrophy with high-risk of early gastric cancer

Atrophic gastritis (AG) is a well-recognized high-risk condition for developing gastric cancer (GC). Gastrin 17 (G17), a hormone secreted from antral G cells, regulates gastric acid secretion, and its serum level is a possible indicator of antral atrophy. Serum pepsinogen is well established as the indicator of AG involving the corpus. Here we investigated whether serum PG and G17 levels would be useful for determining the topographic pattern of AG and estimating the risk of GC. Enrolled were 122 Japanese patients with early GC (114 well- to moderate-differentiated cancers and 8 poorly-differentiated cancers). In addition, 178 subjects without GC were recruited as control from those undergoing endoscopic examination (non-GC group). All subjects were histologically assigned to the following four groups: non-AG, antrum-predominant AG, corpus-predominant AG, and multifocal AG, affecting the antrum and corpus. Serum concentrations of pepsinogen and G17 were determined using ELISA. Multifocal AG was more frequent in the GC group than in the adjusted non-GC group, and had the highest risk of GC (OR 25.1). Serum G17 was significantly decreased with the exacerbation of antral atrophy in the coexistence of corpus atrophy. Serum biomarker profiles showed that the low levels of pepsinogen and G17 could discriminate between multifocal AG and other types of AG, but not with pepsinogen level alone. Serologically defined multifocal AG had the highest cancer risk among other serologically defined AG groups (OR 26.9). In conclusion, the low serum levels of pepsinogen and G17 are predictive of extensive gastric atrophy with high-risk of early GC.

Comparison of the long-term outcomes of endoscopic resection for superficial squamous cell carcinoma and adenocarcinoma of the esophagus in Japan

OBJECTIVES

Few studies have simultaneously evaluated the long-term outcomes of endoscopic resection (ER) for squamous cell carcinoma (SCC) and adenocarcinoma (AC) of the esophagus in Japan. The objective of this study was to evaluate the long-term outcomes of ER for superficial esophageal cancer in consecutive patients.

METHODS

This was a retrospective study from a single institution. From April 2001 to June 2012, 204 patients with SCC and 26 patients with AC were included from a total of 355 consecutive patients who were treated by esophageal ER at the Tohoku University Hospital. Patients with submucosal invasion deeper than 200 μm and lymphovascular involvement were excluded. The intervention followed was endoscopic therapy.

RESULTS

Overall survival, disease-free survival, and recurrence rates were evaluated as long-term outcomes. In the SCC group, during the median observation time of 36.5 months (range, 6-120 months), 22 (10.8%) patients experienced metachronous recurrence, 4 (2.0%) patients experienced local recurrence, and 27 (13.2%) patients died from causes unrelated to SCC. In the AC group, during the median observation time of 45.5 months (range, 6-131 months), one patient (3.8%) experienced metachronous recurrence and two (7.7%) died from causes unrelated to AC. The cumulative 5-year overall survival rates were not significantly different between SCC (75.9%) and AC (88.9%) (P=0.120). The cumulative 5-year disease-free survival rates of SCC (57.1%) were significantly lower than those of AC (85.2%; P=0.017). The cumulative 5-year recurrence rates of SCC (32.0%) were significantly higher than those of AC (4.2%; P=0.023).

CONCLUSIONS

The rate of recurrence after ER was higher in patients with SCC than that in patients with AC. These findings suggest that, by detecting AC of the esophagus earlier, a satisfactory prognosis without recurrence can be expected after ER in Japan, and more rigorous endoscopic follow-up is necessary after ER in patients with SCC than in those with AC.

A prospective comparative study of optical coherence tomography and EUS for tumor staging of superficial esophageal squamous cell carcinoma

BACKGROUND

The precise assessment of superficial esophageal squamous cell carcinomas (SESCCs) limited to the epithelium (EP) or lamina propria mucosa (LPM), the standard indication for endoscopic resection, is important to ensure good outcomes of endoscopic resection. With regard to tomographic imaging techniques, although the accuracy of EUS is practically insufficient, we previously demonstrated that high-resolution optical coherence tomography (OCT) might enable precise assessment for staging in a noninvasive and real-time manner.

OBJECTIVE

To clarify the accuracy of the preoperative staging of SESCCs by using OCT compared with that by using 20-MHz probe-type EUS.

DESIGN

A prospective study.

SETTING

An academic medical center.

PATIENTS

A total of 123 consecutive patients with 131 SESCCs were enrolled from May 2007 to September 2011.

INTERVENTIONS

A specialist examined the patients, by using both OCT and EUS, recorded a representative still image for each lesion, and reported the staging immediately after each examination. Another blinded investigator reviewed the recorded images and reported the staging independently. The histological staging was confirmed by the resected specimens. Finally, we calculated the accuracy of staging by using OCT and EUS.

MAIN OUTCOME MEASUREMENTS

The accuracy of OCT or EUS for EP/LPM.

RESULT

The accuracy for EP/LPM by using OCT was significantly higher than that by using EUS (OCT, 94.6%; HF-EUS, 80.6%; P < .05). Interobserver agreement of OCT and EUS was good and moderate, respectively.

LIMITATIONS

The small number of patients; a single-center, single-operator, nonrandomized, crossover study.

CONCLUSIONS

We prospectively demonstrated that the preoperative staging of SESCC by using OCT was more useful than that by using EUS.

A pilot study of scheduled endoscopic balloon dilation with oral agent tranilast to improve the efficacy of stricture dilation after endoscopic submucosal dissection of the esophagus

BACKGROUNDS AND AIM

As circumferential or near-circumferential endoscopic submucosal dissection (ESD) for superficial esophageal neoplasms might evoke refractory strictures, multiple sessions of endoscopic balloon dilation (EBD) are required. We aimed to assess the effectiveness and safety of oral agent tranilast with EBD for improving the efficacy of stricture dilation after esophageal ESD.

METHODS

In an open-label prospective study at a single institution, 31 asymptomatic consecutive patients with superficial esophageal squamous cell carcinomas were enrolled from April 2007 to October 2010. After ESD, we performed scheduled EBD (twice weekly for 4 wk) with or without administration of oral agent tranilast for 8 weeks. Thereafter, we added additional EBD on the basis of solid criteria-for example, patient's awareness of vomiting >1/wk and inability of passage of routine endoscope through the ESD site. We compared the rates of post-ESD strictures and the numbers of additional EBD sessions for 48 weeks after ESD and the Dysphagia score between tranilast (T)-group and none (N)-group, based on patients' subjective symptoms, at 16, 24, and 48 weeks after ESD.

RESULTS

The percentage of post-ESD strictures in T-group was significantly lower than that in N-group (P=0.04). The median numbers of additional EBD sessions and Dysphagia score at 16 and 24 weeks after ESD in T-group were significantly smaller than those in N-group (P=0.0138, 0.002, 0.005, respectively). No adverse events and no recurrence were observed.

CONCLUSIONS

We demonstrated for the first time that scheduled EBD combined with oral agent tranilast might be effective and safe for improving the efficacy of stricture dilation after esophageal ESD.

Factors Associated With Metachronous Gastric Cancer Development After Endoscopic Submucosal Dissection for Early Gastric Cancer

GOALS

To clarify the factors associated with metachronous gastric cancer development after endoscopic submucosal dissection (ESD) for early gastric cancer.

BACKGROUND

Patients who undergo ESD for early gastric cancer have an appreciable risk of developing metachronous gastric cancer. However, there have been few reports on the association between life style and the development of such cancer.

STUDY

Patients with early gastric cancer who underwent ESD at our institution between 2003 and 2012 were enrolled. Metachronous gastric cancer was defined as secondary gastric cancer detected >1 year after initial ESD. Factors, including age, gender, body mass index, eradication of Helicobacter pylori, cigarette smoking, drinking, and continuous use of a proton pump inhibitor, associated with metachronous gastric cancer development were evaluated by Cox proportional hazard regression analysis.

RESULTS

A total of 539 patients with a mean 53.6-month follow-up period were analyzed. The 5-year cumulative incidence of secondary gastric cancer was 13.0%. Multivariate analysis exhibited that age of 60 years and above [hazard ratio (95% confidence interval)=4.05 (1.23-13.4)] and cigarette smoking [2.12 (1.19-3.78)] were independent risk factors for metachronous gastric cancer development. Furthermore, ≥20 pack-years of smoking [1.51 (1.03-2.24)] was a significant risk factor with a dose-response relationship (P for trend=0.042). There was no significant association between Helicobacter pylori eradication and metachronous gastric cancer development.

CONCLUSIONS

This is the first study to demonstrate the detailed association between cigarette smoking and metachronous gastric cancer development.

The Risk Factors for Metastasis in Non-Ampullary Duodenal Neuroendocrine Tumors Measuring 20 mm or Less in Diameter

BACKGROUND/AIMS

The treatment strategy for non-ampullary duodenal neuroendocrine tumors (NAD-NETs) ≤20 mm in diameter has not been established. In this study, we aimed to evaluate the detailed characteristics of NAD-NETs ≤20 mm in diameter to clarify the risk factors of subsequent metastasis.

METHODS

The patients with NAD-NETs ≤20 mm in diameter who had been treated at 12 institutions between 1992 and 2013 were enrolled. Clinical records were retrieved, and histopathological findings of all cases were centrally reviewed by 2 pathologists.

RESULTS

We studied 49 patients with a mean follow-up period of 66.5 months. Thirty-five patients were initially treated with endoscopic resection (ER), and 14 with surgery. A univariate analysis revealed the ORs and 95% CIs of the risk factors for metastasis were lymphovascular invasion (12.5 [2.01-77.9]), multiple tumors (9.75 [1.46-65.4]), a tumor size of 11-20 mm (6.67 [1.21-36.6]), and World Health Organization grade G2 (7.13 [1.16-43.9]). Five-year overall and disease-specific survival rates were 86.1 and 97.2%, respectively.

CONCLUSION

This is the first study to demonstrate the risk factors of metastasis in NAD-NETs ≤20 mm in diameter. These findings may be helpful for determining the appropriate therapeutic approach and the clinical strategy of treatment following ER.

Activation of type I IFN signaling by NOD1 mediates mucosal host defense against Helicobacter pylori infection

Infection of gastric epithelial cells with Helicobacter pylori (H. pylori) induces a complex array of host protective immune responses. The best known are the adaptive T helper type 1 and type 17 responses that are induced in the gastric lamina propria by antigen-presenting cells via presentation of H. pylori antigens to CD4(+) T cells. Recently, it has become apparent that innate immune responses are also induced by H.pylori infection, both in epithelial cells and in underlying antigen-presenting cells. One important component of these innate responses involves the activity of NOD1, an intra-cellular sensor of peptides derived from the peptidoglycan component of the bacterial cell wall. In this review, we discuss our recent work showing that the signaling pathway utilized by NOD1 results in the generation of type I interferon and that this cytokine mediates both chemokine and cytokine responses that regulate the severity of gastric H. pylori infection.

Estrogen Enhances Esophageal Barrier Function by Potentiating Occludin Expression

BACKGROUND

We recently demonstrated that a female sex hormone, estrogen, suppressed esophageal epithelial injury in a reflux esophagitis model of rat, suggesting that estrogen may play an important role in controlling the progress of the gastro-esophageal reflux disease spectrum. However, the precise mechanism of the action is unclear.

AIM

To investigate the potential role of estrogen in the esophageal barrier function.

METHODS

Male rabbits were pretreated with either continuous release 17β-estradiol or placebo, and the excised esophageal mucosa was subjected to Ussing chamber experiments after the 2-week pre-treatment. The mucosal side of the chamber was perfused with luminal irritants (HCl or acidified sodium nitrite), while the basal side was perfused by modified Krebs buffer. The epithelial barrier function was evaluated by the transmembrane resistance and the epithelial permeability. The intercellular space of the epithelium was investigated with transmission electron microscopy and the expression of tight junction protein, occludin, claudin-1, and claudin-4, with immunoblotting.

RESULTS

Estrogen pre-treatment significantly attenuated the decrease in the transmembrane resistance and the increase in the epithelial permeability induced by luminal irritants. Furthermore, the dilation of the intercellular space induced by luminal HCl was significantly alleviated by 17β-estradiol administration. The baseline occludin expression was significantly potentiated by 17β-estradiol administration.

CONCLUSIONS

This is the first study showing an enhancement of the esophageal barrier function by 17β-estradiol administration. The lack of the protective effect of estrogen could be responsible for the male predominance of erosive reflux esophagitis.