Tomoyuki Oikawa

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.

Gene polymorphisms of NOD1 and interleukin-8 influence the susceptibility to erosive esophagitis in Helicobacter pylori infected Japanese population

Helicobacter pylori (H. pylori) infection generally protects patients from erosive esophagitis through reduction of acid production due to gastric mucosal atrophy. However, there are H. pylori infected patients who still have erosive esophagitis. The reason for this discrepancy remains unclear. We have previously reported that polymorphisms in IL-8 promoter region influence the susceptibility of H. pylori related diseases. On the other hand, nucleotide-binding oligomerization domain 1 (NOD1) is known to play an important role in H. pylori infection. Hence, we hypothesized polymorphisms of these two molecules in H. pylori infected patients may influence the susceptibility to erosive esophagitis. Genomic DNA was extracted from 312 H. pylori infected Japanese, consisting of 110 patients with erosive esophagitis and 202 healthy controls. ND1+32656 T/GG and IL-8-251 A/T polymorphisms were genotyped by direct sequencing. ND1+32656 GG allele and IL-8-251 T/T allele increased the risk of erosive esophagitis with odds ratio (OR) of 1.9 (95% confidence interval (CI) 1.1-3.0, p=0.013) and 1.7 (95% CI 1.1-2.8, p=0.036), respectively. Combination of these two alleles increased the risk with OR of 3.2(95% CI 1.6-6.5, p=0.001). In conclusion, ND1+32656 GG and IL-8-251 T/T allele may be associated with less reactivity to H. pylori infection, and may increase the risk of erosive esophagitis even in H. pylori infected Japanese population.

Enhanced expression of the M2 isoform of pyruvate kinase is involved in gastric cancer development by regulating cancer-specific metabolism

Recent studies have indicated that increased expression of the M2 isoform of pyruvate kinase (PKM2) is involved in glycolysis and tumor development. However, little is known about the role of PKM2 in gastric cancer (GC). Therefore, we examined the expression and function of PKM2 in human GC. We evaluated PKM1 and PKM2 expression by quantitative RT‐PCR in gastric tissues from 10 patients who underwent gastric endoscopic submucosal dissection, 80 patients who underwent gastrectomy, and seven healthy volunteers, and analyzed the correlation with clinicopathological variables. To assess the function of PKM2, we generated PKM2‐knockdown GC cells, and investigated the phenotypic changes. Furthermore, we examined the induction of PKM2 expression by cytotoxin‐associated gene A (CagA), a pathogenic factor of Helicobacter pylori, using CagA‐inducible GC cells. We found that PKM2 was predominantly expressed not only in GC lesions but also in the normal gastric regions of GC patients and in the gastric mucosa of healthy volunteers. The PKM2 expression was significantly higher in carcinoma compared to non‐cancerous tissue and was associated with venous invasion. Knockdown of PKM2 in GC cells caused significant decreases in cellular proliferation, migration, anchorage‐independent growth, and sphere formation in vitro, and in tumor growth and liver metastasis in vivo. The serine concentration‐dependent cell proliferation was also inhibited by PKM2 silencing. Furthermore, we found that PKM2 expression was upregulated by CagA by way of the Erk pathway. These results suggested that enhanced PKM2 expression plays a pivotal role in the carcinogenesis and development of GC in part by regulating cancer‐specific metabolism.

Deficient aldehyde dehydrogenase 2 is associated with increased risk for esophageal squamous cell carcinoma in the presence of gastric hypochlorhydria.

Abstract Objective. In Orientals, deficient aldehyde dehydrogenase 2 (ALDH2) is associated with an increased risk for esophageal squamous cell carcinoma (ESCC). The local metabolism of carcinogenic acetaldehyde in the upper gastrointestinal tract could be involved in the association, but the underlying mechanism has not been fully elucidated. Since an anacidic stomach can promote bacteria-catalyzed local acetaldehyde production, the gastric acid level could also affect acetaldehyde metabolism. This study investigated whether ALDH2-related susceptibility to ESCC differs depending on the gastric secretion level. Material and methods. Sixty-two patients with ESCC and sex- and age-matched normal controls were enrolled in this study. ALDH2 polymorphism was analyzed by polymerase chain-restriction fragment length polymorphism, and those with an inactive allele (ALDH2-1/2-2 or ALDH2-2/2-2) were defined as ALDH2 deficient. Gastrin-stimulated acid output was assessed by endoscopic gastrin test and hypochlorhydria was defined as 0.6 mEq/10 min or lower. Multiple logistic regression analyses were used to adjust for other potential confounders. Results. ALDH2 deficiency or hypochlorhydria was more prevalent in ESCC compared with controls and both showed increased independent associations with ESCC in multivariate analysis. Stratified analysis by the gastric acid secretion level revealed that the associations between the ALDH2 genotype and ESCC differed according to the individual gastric acid secretion levels and that ALDH2 deficiency was a significant risk factor for ESCC exclusively in individuals with hypochlorhydria with an odds ratio (95% confidence interval): 5.0 (1.2–21.2). Conclusion. Microbial production of carcinogen acetaldehyde in the presence of gastric hypochlorhydria is most probably involved in the mechanism of ALDH2-related susceptibility to ESCC.

Association between the Body Mass Index and the Risk of Barrett's Esophagus in Japan

Background: We investigated the association between long-segment Barretts esophagus and obesity in the Japanese population in a multicenter case-control trial. Methods: One hundred thirteen patients with endoscopically detected Barretts esophagus with a length of more than 2 cm and the same number of sex- and age-matched controls were prospectively enrolled. Barretts esophagus was diagnosed based on the Prague C and M criteria. The body mass index (BMI) of the subjects was categorized into the following groups: normal, BMI <22.9; overweight, BMI 23.0-24.9, and obese, BMI >25.0. To determine the association between BMI and the risk of Barretts esophagus, multivariate logistic regression analyses were performed. Results: The basically adjusted regression model adjusted for smoking and alcohol consumption revealed that overweight and obesity were significantly associated with an elevated risk of Barretts esophagus (OR 2.4, 95% CI 1.2-4.7, and OR 2.5, 95% CI 1.3-4.6, respectively). The intensity of the association was not attenuated even after adjustment for gastroesophageal reflux disease-related parameters. Conclusions: An increased BMI was associated with an increased risk for Barretts esophagus through a gastroesophageal reflux-independent mechanism in the Japanese population. Further, unlike in Caucasian populations, being even slightly overweight with a BMI of 23.0-24.9 was an independent risk factor in the Japanese population.

Enhanced expression of semaphorin 3E is involved in the gastric cancer development

Semaphorins and their receptors are abnormally expressed in various cancers, but little is known about the expression and function of semaphorin 3E (SEMA3E) and its receptor, plexin D1 (PLXND1), in gastric cancer development or metastasis. We evaluated SEMA3E and PLXND1 expression by quantitative RT-PCR in gastric tissues from 62 patients who underwent gastrectomy and analyzed the correlation between their expression and clinicopathological variables. To assess the function of SEMA3E, we generated human gastric cancer cell lines with suppressed or increased SEMA3E expression. The expression level of SEMA3E, but not PLXND1, was correlated with lymph node involvement and metastatic progression in gastric cancer. A significant association was observed between a high level of SEMA3E expression and poor differentiation or poor survival in the intestinal type of gastric cancer. SEMA3E knockdown in gastric cancer cells attenuated cell proliferation and metastatic ability in vitro and in vivo. Moreover, SEMA3E caused cell proliferation and anchorage-independent cell growth in the intestinal type of gastric cancer. These results suggested that SEMA3E is likely to be involved in the development of gastric cancer and might also be a therapeutic target for its treatment.

Associations of cigarette smoking and alcohol drinking with stomach cancer survival: A prospective patient cohort study in Japan: Smoking, alcohol intake, and stomach cancer survival

Cigarette smoking and alcohol drinking may affect the prognosis of stomach cancer, but evidence has been inconsistent. We investigated the associations between pretreatment smoking and alcohol drinking and the risk of all‐cause and stomach cancer death among 1,576 patients with histologically confirmed stomach cancer diagnosed during 1997–2010 at a single hospital in Japan. Histories of smoking and alcohol drinking were assessed using a self‐administered questionnaire. The patients were followed until December 31, 2013. The Cox proportional hazards model was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). During 9,625.1 person‐years, 670 all‐cause and 419 stomach cancer deaths were documented. Among the patients overall, ever‐drinking was significantly associated with an increased risk of all‐cause death (HR: 1.25; 95% CI: 1.03–1.51), but not stomach cancer death. Positive linear associations with the frequency of drinking (ptrend = 0.02) and the amount of alcohol consumed per day (ptrend = 0.03) were observed for the risk of all‐cause death. Ever‐smoking was not related to either the risk of all‐cause or stomach cancer death. Conversely, among the patients who underwent curative resection, a significant positive association was found between ever‐smoking and the risk of stomach cancer death (HR: 2.44; 95% CI: 1.17–5.08). A positive association was also found for earlier age at start of smoking (ptrend = 0.0046). Pretreatment smoking and alcohol drinking have significant effects on stomach cancer survival. Lifestyle adjustments throughout life may improve survival.

Risk factors for cervical lymph node metastasis in endoscopically resected superficial hypopharyngeal cancers

OBJECTIVE Hypopharyngeal cancer is a head and neck cancer with a poor prognosis, and most cases show metastases on diagnosis. Cervical lymph node (LN) metastasis is a poor prognostic factor in hypopharyngeal cancer patients. The identification of risk factors for LN metastasis can help guide surgical treatment strategies for these patients. METHODS This retrospective study included 93 superficial hypopharyngeal cancer patients with 109 histopathologically examined lesions treated by endoscopic resection between January 2007 and December 2017. Tumor thickness quantification, quantification of budding nests, immunostaining and other histopathological analyses in paraffin-embedded, formalin-fixed tissue sections (3-μm) of surgical specimens were performed by a certified pathologist. RESULTS Cervical LN metastasis was positive in 18 out of 93 cases (19.3%) and 18 out of 109 lesions (16.5%). No differences were detected in patient characteristics between LN-positive and LN-negative cases, except for tumor thickness, which was significantly larger in LN-positive cases (3119.4±602.2μm vs. 1015.5±129.6μm, respectively; p<0.0001). Univariate analysis showed that tumor thickness ≥1000μm (odds ratio: 5.559, p=0.003), lesions with high budding grade (odds ratio: 5.188, p=0.01) and vascular invasion (odds ratio: 12.710, p=0.007) were significantly associated with cervical LN metastasis. Multivariate analysis revealed tumor thickness≥1000μm as the most significant risk factor for cervical LN metastasis in superficial hypopharyngeal cancer (odds ratio: 3.639, p=0.04). CONCLUSIONS We demonstrate for the first time that high budding grade may serve as powerful predictors of LN metastasis and tumor thickness ≥1000μm is a significant risk factor for LN metastasis of superficial hypopharyngeal cancer. These results should be further examined in future larger scale studies.