Juntaro Matsuzaki

Chromatin remodeling at Alu repeats by epigenetic treatment activates silenced microRNA-512-5p with downregulation of Mcl-1 in human gastric cancer cells.

Epigenetic therapy using DNA methylation inhibitors and histone deacetylase (HDAC) inhibitors has clinical promise for the treatment of human malignancies. To investigate roles of microRNAs (miRNAs) on epigenetic therapy of gastric cancer, the miRNA expression profile was analysed in human gastric cancer cells treated with 5-aza-2′-deoxycytidine (5-Aza-CdR) and 4-phenylbutyric acid (PBA). miRNA microarray analysis shows that most of miRNAs activated by 5-Aza-CdR and PBA in gastric cancer cells are located at Alu repeats on chromosome 19. Analyses of chromatin modification show that DNA demethylation and HDAC inhibition at Alu repeats activates silenced miR-512-5p by RNA polymerase II. In addition, activation of miR-512-5p by epigenetic treatment induces suppression of Mcl-1, resulting in apoptosis of gastric cancer cells. These results suggest that chromatin remodeling at Alu repeats plays critical roles in the regulation of miRNA expression and that epigenetic activation of silenced Alu-associated miRNAs could be a novel therapeutic approach for gastric cancer.

Overexpression of miR-142-5p and miR-155 in Gastric Mucosa-Associated Lymphoid Tissue (MALT) Lymphoma Resistant to Helicobacter pylori Eradication

microRNAs (miRNAs) are small non-coding RNAs that can function as endogenous silencers of target genes and play critical roles in human malignancies. To investigate the molecular pathogenesis of gastric mucosa-associated lymphoid tissue (MALT) lymphoma, the miRNA expression profile was analyzed. miRNA microarray analysis with tissue specimens from gastric MALT lymphomas and surrounding non-tumor mucosae revealed that a hematopoietic-specific miRNA miR-142 and an oncogenic miRNA miR-155 were overexpressed in MALT lymphoma lesions. The expression levels of miR-142-5p and miR-155 were significantly increased in MALT lymphomas which do not respond to Helicobacter pylori (H. pylori) eradication. The expression levels of miR-142-5p and miR-155 were associated with the clinical courses of gastric MALT lymphoma cases. Overexpression of miR-142-5p and miR-155 was also observed in Helicobacter heilmannii-infected C57BL/6 mice, an animal model of gastric MALT lymphoma. In addition, miR-142-5p and miR-155 suppress the proapoptotic gene TP53INP1 as their target. The results of this study indicate that overexpression of miR-142-5p and miR-155 plays a critical role in the pathogenesis of gastric MALT lymphoma. These miRNAs might have potential application as therapeutic targets and novel biomarkers for gastric MALT lymphoma.

Contribution of efflux pumps to clarithromycin resistance in Helicobacter pylori

Background and Aims:  Although clarithromycin (CLR) is one of the most commonly recommended component drugs of Helicobacter pylori eradication regimens, the prevalence of CLR‐resistant H. pylori has been increasing. It is well known that CLR resistance is associated with point mutations in 23S rRNA, but an active multidrug efflux mechanism of H. pylori may also play a role in its drug resistance. At least four gene clusters have been identified as efflux pump systems in H. pylori and the present study was designed to investigate their role in the CLR resistance of clinical isolates of H. pylori.

CD44 variant 9 expression in primary early gastric cancer as a predictive marker for recurrence

Background:Multiple early gastric cancers (EGCs) may develop in 6–14% of patients even after achieving curative endoscopic submucosal dissection (ESD); however, a useful biomarker for predicting recurrence is not available. The present study investigated whether the expression of CD44 variant 9 (CD44v9), a functional cancer stem cell marker, in the primary gastric cancer tissue represents an indicator of recurrence.Methods:Eighty-eight patients who underwent ESD for EGC from 2008 to 2010 were enrolled and monitored for recurrence for 3 years. The expression levels of CD44v9 in the tissue of initial EGCs were evaluated by immunohistochemistry, and the recurrence rate was compared between CD44v9-positive and CD44v9-negative groups. The mucin phenotype and expression of microRNA-21 (miR-21) and programmed cell death protein 4 (PDCD4) were also analysed.Results:The recurrence rate of EGC was significantly higher in the CD44v9-positive group than in the CD44v9-negative group (hazard ratio (HR), 21.8; 95% confidence interval (CI), 5.71–83.1). However, mucin phenotypes and the expression of miR-21 and PDCD4 did not predict recurrence after ESD. Meanwhile, grade of gastric atrophy was also identified as a significant marker of multiple recurrence (HR, 4.95; 95% CI, 1.30–18.8).Conclusion:CD44 variant 9 expression represents a potential predictive marker for recurrence in EGC.

Randomized clinical trial: rikkunshito in the treatment of functional dyspepsia—a multicenter, double-blind, randomized, placebo-controlled study

Rikkunshito, a standardized Japanese herbal medicine, is thought to accelerate gastric emptying and relieve dyspepsia, although no large‐scale, randomized, placebo‐controlled trials of rikkunshito have been conducted. This study aimed to determine the efficacy and safety of rikkunshito for treating functional dyspepsia (FD).

The tumor suppressor microRNA-29c is downregulated and restored by celecoxib in human gastric cancer cells.

MicroRNAs (miRNAs) are small noncoding RNAs that function as endogenous silencers of target genes and play critical roles during carcinogenesis. The selective cyclooxygenase‐2 (COX‐2) inhibitor celecoxib has been highlighted as a potential drug for treatment of gastrointestinal tumors. The aim of this study was to investigate the role of miRNAs in gastric carcinogenesis and the feasibility of a new therapeutic approach for gastric cancer. miRNA expression profiles were examined in 53 gastric tumors including gastric adenomas (atypical epithelia), early gastric cancers and advanced gastric cancers and in gastric cancer cells treated with celecoxib. miRNA microarray analysis revealed that miR‐29c was significantly downregulated in gastric cancer tissues relative to nontumor gastric mucosae. miR‐29c was significantly activated by celecoxib in gastric cancer cells. Downregulation of miR‐29c was associated with progression of gastric cancer and was more prominent in advanced gastric cancers than in gastric adenomas and early gastric cancer. In addition, expression of the oncogene Mcl‐1, a target of miR‐29c, was significantly increased in gastric cancer tissues relative to nontumor gastric mucosae. Activation of miR‐29c by celecoxib induced suppression of Mcl‐1 and apoptosis in gastric cancer cells. These results suggest that downregulation of the tumor suppressor miR‐29c plays critical roles in the progression of gastric cancer. Selective COX‐2 inhibitors may have clinical promise for the treatment of gastric cancer via restoration of miR‐29c.

Dysfunctional Gastric Emptying With Down-regulation of Muscle-Specific MicroRNAs in Helicobacter pylori-Infected Mice

BACKGROUND & AIMS Little is known about the pathogenic mechanisms of functional dyspepsia. We investigated the role of microRNAs (miRNAs) in gastric motility disorders associated with Helicobacter pylori infection. METHODS Male C57BL/6 mice were infected with H pylori. After long-term infection, gastric emptying was examined and compared with that of uninfected mice (controls). The miRNA expression profile was analyzed by miRNA microarray and quantitative reverse-transcriptase polymerase chain reaction. The results obtained from the animal study were confirmed by in vitro experiments. RESULTS Gastric emptying was significantly accelerated in mice after chronic infection with H pylori. Histologic examination showed that the muscular layers of the stomachs of H pylori-infected mice were significantly thickened. The miRNA expression profile revealed that the muscle-specific miRNAs miR-1 and miR-133 were significantly down-regulated in the stomachs after long-term infection with H pylori. However, expression of histone deacetylase 4 and serum response factor, which are reported target genes of miR-1 and miR-133, increased. Down-regulation of miR-1 and miR-133 and increased cell proliferation were observed in C2C12 mouse myoblast cells after coculture with H pylori. CONCLUSIONS Chronic infection with H pylori down-regulates expression of muscle-specific miRNAs and up-regulates expression of histone deacetylase 4 and serum response factor. These might cause hyperplasia in the muscular layer of the stomach and dysfunction in gastric emptying. These findings provide insight into the molecular pathogenesis of gastric motility disorders, including functional dyspepsia.

Ghrelin and oxidative stress in gastrointestinal tract

Oxidative stress is a major cause of the gastrointestinal damage under physical or psychological stress. Ghrelin exhibits gastroprotective effects and they are supposed to be derived from antioxidant effects. In gastroduodenal mucosal injury, the plasma ghrelin levels increase in response to the demand for gastroduodenal cytoprotection. However, in the condition of Helicobacter pylori-induced gastric mucosal severe atrophy, the plasma ghrelin concentration shifted to lower levels. In diabetic gastroparesis, the regulation of ghrelin secretion is impaired with vagal nerve dysfunction. Selective ghrelin agonist is expected to represent a new class of prokinetic agent. In addition, the plasma ghrelin levels are also enhanced by systemic oxidative stress, and ghrelin exhibits antioxidant effects in many organs, such as heart, pancreas, and lung. This suggests that ghrelin would be an important player as a sensor of systemic oxidative stress.

Novel combination of serum microRNA for detecting breast cancer in the early stage.

MicroRNA (miRNA), which are stably present in serum, have been reported to be potentially useful for detecting cancer. In the present study, we examined the expression profiles of serum miRNA in several large cohorts to identify novel miRNA that can be used to detect early stage breast cancer. We comprehensively evaluated the serum miRNA expression profiles using highly sensitive microarray analysis. A total of 1280 serum samples of breast cancer patients stored in the National Cancer Center Biobank were used. In addition, 2836 serum samples were obtained from non‐cancer controls, 451 from patients with other types of cancers, and 63 from patients with non‐breast benign diseases. The samples were divided into a training cohort including non‐cancer controls, other cancers and breast cancer, and a test cohort including non‐cancer controls and breast cancer. The training cohort was used to identify a combination of miRNA that could detect breast cancer, and the test cohort was used to validate that combination. miRNA expressions were compared between patients with breast cancer and non‐breast cancer, and a combination of five miRNA (miR‐1246, miR‐1307‐3p, miR‐4634, miR‐6861‐5p and miR‐6875‐5p) was found to be able to detect breast cancer. This combination had a sensitivity of 97.3%, specificity of 82.9% and accuracy of 89.7% for breast cancer in the test cohort. In addition, this combination could detect early stage breast cancer (sensitivity of 98.0% for Tis).

Classification of functional dyspepsia based on concomitant bowel symptoms

Background  Functional dyspepsia (FD) is a heterogeneous disease, and categorized into postprandial distress syndrome (PDS) and epigastric pain syndrome (EPS). However, many FD patients have overlap of both PDS and EPS. The present study was designed to examine whether FD could be categorized based on the presence of concomitant gastrointestinal symptoms.