Mitsuyoshi Kobayashi

The antidiabetic drug metformin inhibits gastric cancer cell proliferation in vitro and in vivo

Recent studies suggest that metformin, which is commonly used as an oral anti-hyperglycemic agent of the biguanide family, may reduce cancer risk and improve prognosis, but the mechanisms by which metformin affects various cancers, including gastric cancer, remains unknown. The goal of the present study was to evaluate the effects of metformin on human gastric cancer cell proliferation in vitro and in vivo and to study microRNAs (miRNA) associated with antitumor effect of metformin. We used MKN1, MKN45, and MKN74 human gastric cancer cell lines to study the effects of metformin on human gastric cancer cells. Athymic nude mice bearing xenograft tumors were treated with or without metformin. Tumor growth was recorded after 4 weeks, and the expression of cell-cycle-related proteins was determined. In addition, we used miRNA array tips to explore the differences among miRNAs in MKN74 cells bearing xenograft tumors treated with or without metformin in vitro and in vivo. Metformin inhibited the proliferation of MKN1, MKN45, and MKN74 in vitro. Metformin blocked the cell cycle in G0–G1 in vitro and in vivo. This blockade was accompanied by a strong decrease of G1 cyclins, especially in cyclin D1, cyclin-dependent kinase (Cdk) 4, Cdk6 and by a decrease in retinoblastoma protein (Rb) phosphorylation. In addition, metformin reduced the phosphorylation of epidermal growth factor receptor and insulin-like growth factor-1 receptor in vitro and in vivo. The miRNA expression was markedly altered with the treatment of metformin in vitro and in vivo. Various miRNAs altered by metformin also may contribute to tumor growth in vitro and in vivo. Mol Cancer Ther; 11(3); 549–60. ©2012 AACR.

Efficacy and safety of over-the-scope clip: Including complications after endoscopic submucosal dissection

AIM To retrospectively review the results of over-the-scope clip (OTSC) use in our hospital and to examine the feasibility of using the OTSC to treat perforations after endoscopic submucosal dissection (ESD). METHODS We enrolled 23 patients who presented with gastrointestinal (GI) bleeding, fistulae and perforations and were treated with OTSCs (Ovesco Endoscopy GmbH, Tuebingen, Germany) between November 2011 and September 2012. Maximum lesion size was defined as lesion diameter. The number of OTSCs to be used per patient was not decided until the lesion was completely closed. We used a twin grasper (Ovesco Endoscopy GmbH, Tuebingen, Germany) as a grasping device for all the patients. A 9 mm OTSC was chosen for use in the esophagus and colon, and a 10 mm device was used for the stomach, duodenum and rectum. The overall success rate and complications were evaluated, with a particular emphasis on patients who had undergone ESD due to adenocarcinoma. In technical successful cases we included not only complete closing by using OTSCs, but also partial closing where complete closure with OTSCs is almost difficult. In overall clinical successful cases we included only complete closing by using only OTSCs perfectly. All the OTSCs were placed by 2 experienced endoscopists. The sites closed after ESD included not only the perforation site but also all defective ulcers sites. RESULTS A total of 23 patients [mean age 77 years (range 64-98 years)] underwent OTSC placement during the study period. The indications for OTSC placement were GI bleeding (n = 9), perforation (n = 10), fistula (n = 4) and the prevention of post-ESD duodenal artificial ulcer perforation (n = 1). One patient had a perforation caused by a glycerin enema, after which a fistula formed. Lesion closure using the OTSC alone was successful in 19 out of 23 patients, and overall success rate was 82.6%. A large lesion size (greater than 20 mm) and a delayed diagnosis (more than 1 wk) were the major contributing factors for the overall unsuccessful clinical cases. The location of the unsuccessful lesion was in the stomach. The median operation time in the successful cases was 18 min, and the average observation time was 67 d. During the observation period, none of the patients experienced any complications associated with OTSC placement. In addition, we successfully used the OTSC to close the perforation site after ESD in 6 patients. This was a single-center, retrospective study with a small sample size. CONCLUSION The OTSC is effective for treating GI bleeding, fistulae as well as perforations, and the OTSC technique proofed effective treatment for perforation after ESD.

Effect of the anti-diabetic drug metformin in hepatocellular carcinoma in vitro and in vivo.

Metformin is a commonly used oral anti-hyperglycemic agent of the biguanide family. Recent studies suggest that metformin may reduce cancer risk and improve prognosis. However, the antitumor mechanism of metformin in several types of cancers, including hepatocellular carcinoma (HCC), has not been elucidated. The goal of the present study was to evaluate the effects of metformin on HCC cell proliferation in vitro and in vivo, and to study microRNAs (miRNAs) associated with the antitumor effect of metformin in vitro. We used the cell lines Alex, HLE and Huh7, and normal hepatocytes to study the effects of metformin on human HCC cells. In an in vivo study, athymic nude mice bearing xenograft tumors were treated with metformin or left untreated. Tumor growth was recorded after 4 weeks, and the expression of cell cycle-related proteins was determined. Metformin inhibited the proliferation of Alex, HLE and Huh7 cells in vitro and in vivo. Metformin blocked the cell cycle in G0/G1 in vitro and in vivo. This blockade was accompanied by a strong decrease of G1 cyclins, especially cyclin D1, cyclin E and cyclin-dependent kinase 4 (Cdk4). In addition, microRNA (miRNA) expression was markedly altered by the treatment with metformin in vitro and in vivo. In addition, various miRNAs induced by metformin also may contribute to the suppression of tumor growth. Our results demonstrate that metformin inhibits the growth of HCC, possibly by inducing G1 cell cycle arrest through the alteration of microRNAs.

Establishment of pure NOTES procedure using a conventional flexible endoscope: review of six cases of gastric gastrointestinal stromal tumors

An increasing number of reports have recently been published on hybrid natural orifice transluminal endoscopic surgery (NOTES). These reports do not address how to complete an operation with a flexible endoscope alone (pure NOTES), but rather how to combine use of an endoscope and a laparoscope. Surgical procedures using flexible and rigid endoscopes have been developed using different processes and concepts. Recognizing this conceptual difference, we conducted a study to address how to establish a pure NOTES procedure. Six patients with gastric gastrointestinal stromal tumors (GISTs) underwent hybrid NOTES. Each case was retrospectively reviewed to determine the appropriateness of the treatment and the usefulness of the endoscopic submucosal dissection (ESD) method, double-scope method, spaced perforation method, duodenal balloon occlusion method, and loop clip technique. The development of operative procedures that take advantage of the characteristics of flexible endoscopes, even with conventional flexible endoscopic devices and conventional endoscopes alone, may contribute to the realization of pure NOTES.

Successful closing of duodenal ulcer after endoscopic submucosal dissection with over-the-scope clip to prevent delayed perforation.

Closure of post‐endoscopic submucosal dissection (ESD) duodenal artificial ulcer is not common in the clinical setting. We consider that post‐ESD ulcer closure by an over‐the‐scope‐clip (OTSC) method is one of the most effective ways to prevent delayed perforation. We report here two cases of mucosal duodenal cancer in a 65‐year‐old woman and in a 78‐year‐old man. Pathological examinations of the resected specimens revealed well‐differentiated adenocarcinomas. In these two clinical cases, we successfully carried out complete closures of post‐ESD duodenal ulcer using OTSC without any complications.

Esophageal function worsens with long duration of diabetes

BackgroundThe aim of this study was to assess the relationship between the duration of diabetes and esophageal dysfunction.MethodsWe examined 66 patients with type 2 diabetes. Duration of diabetes was determined by asking patients and from their medical records. The patients were divided into three groups according to the duration of their diabetes: group A, 1–4 years, n = 26; group B, 5–9 years, n = 20; and group C, 10+ years, n = 20. Ambulatory esophageal 24-h pH and motility were monitored, and gastroesophageal reflux and esophageal motility disorders were estimated in detail.ResultsWhen the duration of diabetes was long, the percentage of time with pH < 4 tended to increase. The amplitude of esophageal peristaltic waves and the frequency of effective peristalsis were reduced when the duration of diabetes was long. A significant correlation was observed between the duration of diabetes and the frequency of effective peristalsis. The number of esophageal peristaltic waves per minute and the percentage of multipeaked peristaltic waves increased significantly in group B, and decreased when the duration of diabetes became longer.ConclusionsGastroesophageal reflux and esophageal motility disorders worsened with long duration of diabetes. These esophageal dysfunctions should be considered in patients with long-standing diabetes.

Antitumor effect of metformin in esophageal cancer: In vitro study

Recent studies suggest that metformin, which is a member of the biguanide family and commonly used as an oral anti-hyperglycemic agent, may reduce cancer risk and improve prognosis of numerous types of cancer. However, the mechanisms underlying the antitumor effect of metformin on esophageal cancer remain unknown. The goal of the present study was to evaluate the effects of metformin on the proliferation of human ESCC in vitro, and to study changes in the expression profile of microRNAs (miRNAs), since miRNAs have previously been associated with the antitumor effects of metformin in other human cancers. The human ESCC cell lines T.T, KYSE30 and KYSE70 were used to study the effects of metformin on human ESCC in vitro. In addition, we used miRNA array tips to explore the differences between miRNAs in KYSE30 cells with and without metformin treatment. Metformin inhibited the proliferation of T.T, KYSE30 and KYSE70 cells in vitro. Metformin blocked the cell cycle in G0/G1 in vitro. This blockade was accompanied by a strong decrease of G1 cyclins, especially cyclin D1, as well as decreases in cyclin-dependent kinase (Cdk)4, Cdk6 and phosphorylated retinoblastoma protein (Rb). In addition, the expression of miRNAs was markedly altered with the treatment of metformin in vitro. Metformin inhibited the growth of three ESCC cell lines, and this inhibition may have involved reductions in cyclin D1, Cdk4 and Cdk6.

Bloc biopsy by using submucosal endoscopy with a mucosal flap method for gastric subepithelial tumor tissue sampling (with video).

Subepithelial tumors (SETs) include widely malignant tumors such as GI stromal tumors, malignant lymphomas, carcinoid tumors, gastric cancers similar to SETs, and benign tumors such as leiomyomas, aberrant pancreas, and lipomas. Currently, minimally invasive local resection techniques such as hybrid natural orifice transluminal endoscopic surgery (NOTES), which consists of endoscopic full-thickness gastric resection, have been developed for the treatment of GI stromal tumors. 1 However, there is no consensus regarding the optimal strategy for the tissue diagnosis of SETs before determining the plans for further management such as surgical resection or observation. SET differentiation is essentially important, because different types of lesions may need different management, prognoses, and therapeutic options. EUS morphologic features alone have limited specificity for the diverse subtypes of SETs, and EUS cannot differentiate between a benign or malignant origin. Recently, several diagnostic methods have been proposed for the tissue diagnosis of SETs. EUS-guided FNA (EUS-FNA) biopsy has been introduced as an easy, safe, and valuable method for obtaining tissue samples for the accurate diagnosis of GI SETs. 2-7 In

Antidiabetic drug metformin inhibits esophageal adenocarcinoma cell proliferation in vitro and in vivo.

Esophageal carcinoma is the eighth most common cancer worldwide and the sixth leading cause of cancer-related deaths, with one of the worst prognoses of any form of cancer. Treatment with the anti-diabetic drug metformin has been associated with reduced cancer incidence in patients with type 2 diabetes. This study therefore evaluated the effects of metformin on the proliferation, in vitro and in vivo, of human esophageal adenocarcinoma cells, as well as the microRNAs associated with the antitumor effects of metformin. Metformin inhibited the proliferation of the esophageal adenocarcinoma cell lines OE19, OE33, SK-GT4 and OACM 5.1C, blocking the G0 to G1 transition in the cell cycle. This was accompanied by strong reductions in G1 cyclins, especially cyclin D1, cyclin-dependent kinase (Cdk)4, and Cdk6, and decreases in retinoblastoma protein phosphorylation. In addition, metformin reduced the phosphorylation of epidermal growth factor receptor and insulin-like growth factor and insulin-like growth factor-1 receptor, as well as angiogenesis-related proteins, such as vascular endothelial growth factor, tissue inhibitor of metalloproteinases (TIMP)-1, and TIMP-2. Metformin also markedly altered microRNA expression. Treatment with metformin of athymic nude mice bearing xenograft tumors reduced tumor proliferation. These findings suggest that metformin may have clinical use in the treatment of esophageal adenocarcinoma.

Local steroid injection into the artificial ulcer created by endoscopic submucosal dissection for gastric cancer: prevention of gastric deformity

BACKGROUND AND STUDY AIMS Endoscopic submucosal dissection (ESD) of large gastric lesions results in an extensive artificial ulcer that can lead to marked gastric deformity. The aim of the current study was to evaluate therapeutic efficacy in the prevention of gastric deformity of local triamcinolone acetonide (TCA) injection into the extensive artificial ulcer following ESD. PATIENTS AND METHODS A total of 45 patients who were diagnosed with early gastric cancer were enrolled. Patients were randomly assigned by the sealed-envelope randomization method to either local TCA injections (n = 21) or sham-control (n = 20) groups. Two clips were placed at the two maximum outer edges of the artificial ulcer after the lesion had been resected (Day 0). Local TCA injections were performed on postoperative Day 5 and Day 12. The distance between the two clips was measured by endoscopic measuring forceps on Days 5, 12, 30, and 60. Granulation formation and gastric deformity were evaluated by visual analog scale (VAS) on Days 30 and 60. RESULTS Local TCA injection did not alter clip-to-clip distance on postoperative Day 60, and formation of flat granulation tissue over the ulcer was followed by regenerative mucosa without any gastric deformity. The sham-control group showed significant shortening of clip-to-clip distance compared with the local steroid-injected group and protruded forms of granulation tissue with mucosal convergence. Histological evaluation revealed prominent growth of neovessels, swelling, and marked increases in endothelial cells in the local steroid-injected group compared with the sham-control group. CONCLUSIONS Local steroid injection into the floor of a post-ESD artificial ulcer promotes the formation of granulation tissue at an early stage of the healing process leading to regeneration of gastric mucosa without mucosal convergence or gastric deformity.