Activation of Signal Transduction and Activator of Transcription 3 Signaling Contributes to Helicobacter-Associated Gastric Epithelial Proliferation and Inflammation.

BACKGROUND/AIM: Although IL-6-mediated activation of the signal transduction and activator of transcription 3 (STAT3) axis is involved in inflammation and cancer, the role of STAT3 in Helicobacter-associated gastric inflammation and carcinogenesis is unclear. This study investigated the role of STAT3 in gastric inflammation and carcinogenesis and examined the molecular mechanism of Helicobacter-induced gastric phenotypes. METHODS: To evaluate the contribution of STAT3 to gastric inflammation and carcinogenesis, we used wild-type (WT) and gastric epithelial conditional Stat3-knockout (Stat3Δgec ) mice. Mice were infected with Helicobacter felis and euthanized at 18 months postinfection. Mouse gastric organoids were treated with recombinant IL-6 (rIL-6) or rIL-11 and a JAK inhibitor (JAKi) to assess the role of IL-6/STAT3 signaling in vitro. RESULTS: Inflammation and mucous metaplasia were more severe in WT mice than in Stat3Δgec mice. The epithelial cell proliferation rate and STAT3 activation were increased in WT mice. Application of rIL-6 and rIL-11 induced expression of intestinal metaplasia-associated genes, such as Tff2; this induction was suppressed by JAKi administration. CONCLUSIONS: Loss of STAT3 signaling in the gastric mucosa leads to decreased epithelial cell proliferation, atrophy, and metaplasia in the setting of Helicobacter infection. Therefore, activation of STAT3 signaling may play a key role in Helicobacter-associated gastric carcinogenesis.

Effects of Vonoprazan Compared with Esomeprazole on the Healing of Artificial Postendoscopic Submucosal Dissection Ulcers: A Prospective, Multicenter, Two-Arm, Randomized Controlled Trial.

BACKGROUND: Vonoprazan affords more clinical benefits than proton pump inhibitors (PPIs) during the healing of gastroduodenal ulcers. However, it remains controversial whether vonoprazan is more effective than PPIs when used to heal artificial ulcers arising after endoscopic submucosal dissection (ESD). AIM: This study investigated the effects of vonoprazan compared with esomeprazole on the healing of post-ESD artificial ulcers. METHODS: Sixty patients who underwent gastric ESD between May 2015 and May 2017 were randomized to treatment with vonoprazan (V group) or esomeprazole (E group) for 8 weeks. Upper endoscopy was performed at 4 and 8 weeks after ESD, and drug effects were estimated based on the ulcer healing rates and shrinkage rates. RESULTS: Fifty-three patients were analyzed. The respective 4- and 8-week ulcer healing rates did not differ significantly between V and E groups (8.0 versus 11.5%, P = 0.669; 88.9 versus 84.6%, P = 0.420). Similarly, the respective 4- and 8-week ulcer shrinkage rates did not differ significantly between V and E groups (96.8 versus 97.5%, P = 0.656; 100 versus 100%, P = 0.257). CONCLUSION: The healing of artificial ulcers after ESD did not differ using vonoprazan or esomeprazole. Both vonoprazan and esomeprazole were effective when used to promote artificial ulcer healing after ESD.

Overexpression of HER2 in the pancreas promotes development of intraductal papillary mucinous neoplasms in mice.

Pancreatic ductal adenocarcinoma (PDA) has a 5-year survival rate of less than 5% and is the sixth leading cause of cancer death. Although KRAS mutations are one of the major driver mutations in PDA, KRAS mutation alone is not sufficient to induce invasive pancreatic cancer in mice model. HER2, also known as ERBB2, is a receptor tyrosine kinase, and overexpression of HER2 is associated with poor clinical outcomes in pancreatic cancer. However, no report has shown whether HER2 and its downstream signaling contributes to the pancreatic cancer development. By immunohistochemical analysis in human cases, HER2 protein expression was detected in 40% of PDAs and 29% of intraductal papillary mucinous carcinomas, another type of pancreatic cancer. In a mouse model, we showed overexpression of activated HER2 (HER2 NT ) in the pancreas, in which cystic neoplastic lesions resembling intraductal papillary mucinous neoplasm-like lesions in humans had developed. We also found that HER2 NT cooperated with oncogenic Kras to accelerate the development of pancreatic intraepithelial neoplasms. In addition, using pancreatic organoids in 3D cultures, we found that organoids cultured from HER2 NT /Kras double transgenic mice showed proliferative potential and tumorigenic ability cooperatively. HER2-signaling inhibition was suggested to be an new therapeutic target in some types of PDAs.

Correction to: Helicobacter-induced gastric inflammation alters the properties of gastric tissue stem/progenitor cells.

CORRECTION: Unfortunately, the original article [1] contained an error incorporated during production. A duplicated version of Table 1 was published in place of Table 2. Table 2 has been corrected in the original article and is also included correctly below.

Histological verification of the usefulness of magnifying endoscopy with narrow-band imaging for horizontal margin diagnosis of differentiated-type early gastric cancers.

BACKGROUND: Although magnifying endoscopy with narrow-band imaging (ME-NBI) can help identify the horizontal margin (HM) of early gastric cancer (EGC), little is known about the factors that can clarify the HM by using ME-NBI. We aimed to characterize the pathological features of lesions in which the HM was identified using ME-NBI. METHODS: The HMs of 639 differentiated-type EGCs treated with endoscopic submucosal dissection or surgery were analyzed using conventional endoscopy and ME-NBI. The number and width of the intervening parts (IP) and the number, width, and depth of the subepithelial capillaries (SEC) in cancerous and noncancerous areas were measured. RESULTS: In 13 lesions (2.0%), more than 90% of the HM was not recognized with conventional endoscopy, but 11 of these lesions were detectable with ME-NBI (NBI group). The HMs of the other 626 lesions were mostly recognized using conventional endoscopy (WLI/CE group). In the NBI group, the IP width, standard deviation (SD), and number of IPs did not significantly differ between the cancerous and noncancerous areas. However, the SEC number was significantly larger and the depth was shallower in cancerous areas. In the WLI/CE group, the IP width and SD were significantly larger, but the IP number was significantly smaller in cancerous areas. The SEC depth was significantly shallower in cancerous areas. CONCLUSIONS: Differences of IP width, SD, and IP number may be factors for identifying HMs with conventional endoscopy. Because NBI can better visualize vessel structures, the increased SEC number and shallow SECs may clarify the HM.

Helicobacter-induced gastric inflammation alters the properties of gastric tissue stem/progenitor cells.

BACKGROUND: Although Helicobacter-induced gastric inflammation is the major predisposing factor for gastric carcinogenesis, the precise mechanism by which chronic gastritis causes gastric cancer remains unclear. Intestinal and spasmolytic polypeptide-expressing metaplasia (SPEM) is considered as precancerous lesions, changes in epithelial tissue stem/progenitor cells after chronic inflammation has not been clarified yet. In this study, we utilized three-dimensional gastric epithelial cell culture systems that could form organoids, mimicking gastric epithelial layer, and characterized the changes in epithelial cells after chronic Helicobacter felis infection. METHODS: We used three mice model; 1) long-term H. felis infection, 2) H. felis eradication, and 3) MNU chemical carcinogenesis model. We performed cRNA microarray analysis after organoid culture, and analyzed the effects of chronic gastric inflammation on tissue stem cells, by the size of organoid, mRNA expression profile and immunohistochemical analysis. RESULTS: The number of organoids cultured from gastric epithelial cells was significantly higher in organoids isolated from H. felis-infected mice compared with those from uninfected gastric mucosa. Based on the mRNA expression profile, we found that possible stem cell markers such as Cd44, Dclk1, and genes associated with the intestinal phenotype, such as Villin, were increased in organoids isolated from H. felis-infected mucosa compared with the control. The upregulation of these genes were cancelled after H. felis eradication. In a xenograft model, tumors were generated only from organoids cultured from carcinogen-treated gastric mucosa, not from H. felis infected mucosa or control organoids. CONCLUSIONS: Our results suggested that, as a possible mechanism of gastric carcinogenesis, chronic inflammation induced by H. felis infection increased the number of tissue stem/progenitor cells and the expression of stem cell markers. These findings suggest that chronic inflammation may alter the direction of differentiation toward undifferentiated state and that drawbacks may enable cells to redifferentiate to intestinal metaplasia or neoplasia.

The feasibility of colorectal endoscopic submucosal dissection for the treatment of residual or recurrent tumor localized in therapeutic scar tissue.

BACKGROUND AND STUDY AIMS: Endoscopic submucosal dissection (ESD) is used to treat superficial colorectal tumors. Previous studies have reported the efficacy of ESD for treating residual or local recurrent colorectal tumors. This study sought to evaluate the efficacy of ESD in treating these lesions and to assess factors that prevent successful ESD. METHODS: This retrospective study assessed 25 cases of residual or local recurrent lesions that were previously treated using EMR (18 lesions), TEM (5 lesions), ESD (1 lesion) or surgery (1 lesion), and 459 primary lesions treated using ESD between April 2008 and September 2015. Clinicopathological characteristics, treatment outcome and adverse events were compared between groups with or without scar tissue. Factors related to perforation and a prolonged treatment time, which indicate the likelihood of technical difficulties, were identified using multiple logistic regression analysis. RESULTS: In residual or local recurrent lesions groups, patients experienced more perforations (32 % vs 4 %, P  < 0.001) and required a longer treatment time (117 min vs 61 min, P  < 0.001) compared with the primary lesions group. Both groups showed a similar curative resection rate. Emergency surgery was not needed in any case. Multiple logistic regression analysis indicated that tumor location and therapeutic scar tissue were high risk factors for perforation, and that large tumor size and therapeutic scar tissue were high risk factors for prolonged treatment time. CONCLUSIONS: ESD for residual or local recurrent colorectal tumors is a technically challenging, but effective and minimally invasive treatment. When performed carefully with sufficient proficiency, it is a useful treatment option.

Familial Adenomatous Polyposis with Multiple Helicobacter-negative Early Gastric Cancers Treated by Endoscopic Submucosal Dissection.

Stomach cancer rarely develops in patients with familial adenomatous polyposis (FAP), and Helicobacter pylori infection may increase the risk of FAP-related gastric cancer. We describe the case of a 64-year-old woman who developed multiple synchronous early gastric cancers without H. pylori infection. Nine cancer lesions were successfully treated by endoscopic submucosal dissection. An immunohistochemical analysis revealed that the tumors were positive for mucin (MUC)2, MUC6, and CDX2, but negative for MUC5AC, suggesting that the tumors were gastrointestinal mixed type. Periodical endoscopic surveillance is important for the detection of cancers at an early stage.

c-Jun N-terminal kinase in pancreatic tumor stroma augments tumor development in mice.

Pancreatic ductal adenocarcinoma (PDAC) is a life-threatening disease and there is an urgent need to develop improved therapeutic approaches. The role of c-Jun N-terminal kinase (JNK) in PDAC stroma is not well defined even though dense desmoplastic reactions are characteristic of PDAC histology. We aimed to explore the role of JNK in PDAC stroma in mice. We crossed Ptf1aCre/+ ;KrasG12D/+ mice with JNK1-/- mice to generate Ptf1aCre/+ ;KrasG12D/+ ;JNK1-/- (Kras;JNK1-/- ) mice. Tumor weight was significantly lower in Kras;JNK1-/- mice than in Kras;JNK1+/- mice, whereas histopathological features were similar. We also transplanted a murine PDAC cell line (mPC) with intact JNK1 s.c. into WT and JNK1-/- mice. Tumor diameters were significantly smaller in JNK1-/- mice. Phosphorylated JNK (p-JNK) was activated in α-smooth muscle actin (SMA)-positive cells in tumor stroma, and mPC-conditioned medium activated p-JNK in tumor-associated fibroblasts (TAF) in vitro. Relative expression of Ccl20 was downregulated in stimulated TAF. Ccl20 is an important chemokine that promotes CD8+ T-cell infiltration by recruitment of dendritic cells, and the number of CD8+ T cells was decreased in Kras;JNK1+/- mice compared with Kras;JNK1-/- mice. These results suggest that the cancer secretome decreases Ccl20 secretion from TAF by activation of JNK, and downregulation of Ccl20 secretion might be correlated with reduction of infiltrating CD8+ T cells. Therefore, we concluded that inhibition of activated JNK in pancreatic tumor stroma could be a potential therapeutic target to increase Ccl20 secretion from TAF and induce accumulation of CD8+ T cells, which would be expected to enhance antitumor immunity.

Diagnosis of pancreatic lesions collected by endoscopic ultrasound-guided fine-needle aspiration using next-generation sequencing.

Endoscopic ultrasound-guided fine-needle aspiration (EUF-FNA) has improved the diagnosis of pancreatic lesions. Next-generation sequencing (NGS) facilitates the production of millions of sequences concurrently. Therefore, in the current study, to improve the detectability of oncogenic mutations in pancreatic lesions, an NGS system was used to diagnose EUS-FNA samples. A total of 38 patients with clinically diagnosed EUS-FNA specimens were analyzed; 27 patients had pancreatic ductal adenocarcinoma (PDAC) and 11 had non-PDAC lesions. DNA samples were isolated and sequenced by NGS using an Ion Personal Genome Machine system. The Cancer Hotspot Panel v2, which includes 50 cancer-related genes and 2,790 COSMIC mutations, was used. A >2% mutation frequency was defined as positive. KRAS mutations were detected in 26 of 27 PDAC aspirates (96%) and 0 of 11 non-PDAC lesions (0%). The G12, G13, and Q61 KRAS mutations were found in 25, 0, and 1 of the 27 PDAC samples, respectively. Mutations were confirmed by TaqMan® polymerase chain reaction analysis. TP53 mutations were detected in 12 of 27 PDAC aspirates (44%). SMAD4 was observed in 3 PDAC lesions and cyclin-dependent kinase inhibitor 2A in 4 PDAC lesions. Therefore, the current study was successfully able to develop an NGS assay with high clinical sensitivity for EUS-FNA samples.

Case of a tumor comprising gastric cancer and duodenal neuroendocrine tumor.

The present report describes a rare case of a tumor composed of early gastric cancer and a duodenal neuroendocrine tumor (NET). A 78-year-old woman underwent esophagogastroduodenoscopy at a local institution for screening of the upper gastrointestinal tract which revealed a protruded tumor through the pyloric ring from the pyloric antrum. The tumor was too large to treat at the facility; consequently, she was referred to our hospital for further management. Esophagogastroduodenoscopy with tumor biopsy of the lesion revealed the diagnosis of early gastric cancer. Endoscopic submucosal dissection was performed with sufficient free margins in both vertical and horizontal directions. Histopathological findings showed NET confined to the submucosal layer and covered by well-differentiated adenocarcinoma. Immunohistochemical stainings showed that the two lesions existed continuously. While the possibility of a collision cancer was considered, it was suggested that the two lesions existed continuously. Finally, the tumor was diagnosed as gastric cancer composed of duodenal NET G1, with a lymphatic invasion of NET component.

Intestine-specific homeobox (ISX) induces intestinal metaplasia and cell proliferation to contribute to gastric carcinogenesis.

BACKGROUND: Helicobacter pylori induces chronic inflammation and intestinal metaplasia (IM) through genetic and epigenetic changes and activation of intracellular signaling pathways that contribute to gastric carcinogenesis. However, the precise mechanism of IM in gastric carcinogenesis has not been fully elucidated. We previously found that intestine-specific homeobox (ISX) mRNA expression increased in organoids cultured from Helicobacter-infected mouse mucosa. In this study, we elucidate the role of ISX in the development of IM and gastric carcinogenesis. METHODS: ISX expression was assessed in Helicobacter-infected mouse and human gastric mucosa. MKN45 gastric cancer cells were co-cultured with H. pylori to determine whether Helicobacter infection induced ISX expression. We established stable MKN45 transfected cells expressing ISX (Stable-ISX MKN45) and performed a spheroid colony formation assay and a xenograft model. We performed ISX immunohistochemistry in cancer and adjacent gastric tissues. RESULTS: ISX expression was increased in mouse and human gastric mucosa infected with Helicobacter. The presence of IM and H. pylori infection in human stomach was correlated with ISX expression. H. pylori induced ISX mRNA and protein expression. CDX1/2, cyclinD1, and MUC2 were upregulated in Stable-ISX MKN45, whereas MUC5AC was downregulated. Stable-ISX MKN45 cells formed more spheroid colonies, and had high tumorigenic ability. ISX expression in gastric cancer and adjacent mucosa were correlated. CONCLUSIONS: ISX expression induced by H. pylori infection may lead to IM and hyperproliferation of gastric mucosa through CDX1/2 and cyclinD1 expression, contributing to gastric carcinogenesis.