Shusaku Tsutsui

Production of adiponectin, an anti-inflammatory protein, in mesenteric adipose tissue in Crohn’s disease

Background and aims: A characteristic feature of Crohn’s disease (CD) is mesenteric adipose tissue hypertrophy. Mesenteric adipocytes or specific proteins secreted by them may play a role in the pathogenesis of CD. We recently identified adiponectin as an adipocyte specific protein with anti-inflammatory properties. Here we report on expression of adiponectin in mesenteric adipose tissue of CD patients. Methods and results: Mesenteric adipose tissue specimens were obtained from patients with CD (n = 22), ulcerative colitis (UC) (n = 8) and, for controls, colon carcinoma patients (n = 28) who underwent intestinal resection. Adiponectin concentrations were determined by enzyme linked immunosorbent assay, and adiponectin mRNA levels were determined by real time quantitative reverse transcription-polymerase chain reaction. Tissue concentrations and release of adiponectin were significantly increased in hypertrophied mesenteric adipose tissue of CD patients compared with normal mesenteric adipose tissue of CD patients (p = 0.002, p = 0.040, respectively), UC patients (p = 0.002, p = 0.003), and controls (p<0.0001, p<0.0001). Adiponectin mRNA levels were significantly higher in hypertrophied mesenteric adipose tissue of CD patients than in paired normal mesenteric adipose tissue from the same subjects (p = 0.024). Adiponectin concentrations in hypertrophied mesenteric adipose tissue of CD patients with an internal fistula were significantly lower than those of CD patients without an internal fistula (p = 0.003). Conclusions: Our results suggest that adipocytes in hypertrophied mesenteric adipose tissue produce and secrete significant amounts of adiponectin, which could be involved in the regulation of intestinal inflammation associated with CD.

Gastrin Induces Heparin-Binding Epidermal Growth Factor-like Growth Factor in Rat Gastric Epithelial Cells Transfected With Gastrin Receptor

BACKGROUND & AIMS Parietal cells express heparin-binding epidermal growth factor (EGF)-like growth factor (HB-EGF). However, it is unknown whether HB-EGF mediates the trophic action of gastrin. The purpose of this study was to determine whether gastrin modulates the expression of HB-EGF, which mediates the proliferative effects of gastrin on gastric epithelial cells. METHODS RGM1 cells, a rat gastric epithelial cell line, were transfected with a human gastrin receptor complementary DNA. Gastrin induction of messenger RNAs (mRNAs) for EGF-related polypeptides was assayed by Northern blotting. Processing of cell surface-associated proHB-EGF and secretion of HB-EGF were determined by flow cytometry and Western blotting, respectively. Tyrosine phosphorylation of the EGF receptor was assayed by immunoprecipitation and Western blotting with an antiphosphotyrosine antibody. Cell growth was evaluated by [3H]thymidine incorporation. RESULTS Gastrin induced expression of HB-EGF mRNA, processing of proHB-EGF, release of HB-EGF into the medium, and tyrosine phosphorylation of the EGF receptor. The growth-stimulatory effects of gastrin were partly inhibited by anti-rat HB-EGF serum and completely blocked by AG1478, an EGF receptor-specific tyrphostin. CONCLUSIONS The findings suggest that HB-EGF at least partially mediates the proliferative effects of gastrin on gastric epithelial cells.

Pathophysiology, diagnosis, and treatment of gastrointestinal stromal tumors.

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. Activating mutations of KIT or the platelet-derived growth factor receptor alpha gene (PDGFRA) have been identified in the vast majority of GISTs. The respective oncoproteins exhibit constitutive tyrosine kinase activity and promote cell growth. KIT and PDGFRA mutations are rarely found in GISTs in patients with neurofibromatosis type 1 (NF1) suggesting that the pathogenesis of GIST in NF1 patients is different from that in non-NF1 patients. Endoscopic diagnosis of GIST is usually difficult. Endoscopic ultrasonography (EUS)-guided fine-needle aspiration biopsy (EUS-FNAB) is a useful method for the diagnosis of GIST and for the detection of KIT or PDGFRA mutations. Imatinib mesylate, a tyrosine kinase inhibitor known to inhibit the activities of BCR-ABL, KIT, and PDGFR, is currently being used for the treatment of both chronic myeloid leukemia and metastatic GIST. The clinical response to imatinib therapy correlates with the types of mutations of KIT and PDGFRA, and the determination of KIT and PDGFRA mutations is useful for predicting the effect of imatinib. Resistance to imatinib after an initial response has been reported; secondary point mutations in KIT or PDGFRA that confer imatinib resistance are the most common mechanisms responsible for acquired resistance to imatinib. The continued development of target-specific therapies should increase the probability of cure in most patients with GISTs.

SHORT-TERM OUTCOMES OF ENDOSCOPIC SUBMUCOSAL DISSECTION (ESD) FOR EARLY GASTRIC NEOPLASM: MULTICENTER SURVEY BY OSAKA UNIVERSITY ESD STUDY GROUP

Background:  Endoscopic submucosal dissection (ESD) was developed for en bloc removal of large and flat gastrointestinal tract neoplasms. In Japan, ESD is performed under conscious sedation. The risks for sedation‐related complications of ESD, such as postoperative pneumonia, have not been evaluated. The aim of this study was to evaluate the incidence of postoperative pneumonia after ESD in a multicenter survey.

Adiponectin prevents progression of steatohepatitis in mice by regulating oxidative stress and Kupffer cell phenotype polarization.

Aim:  We reported previously that hypoadiponectinemia enhances hepatic oxidative stress and accelerates progression of nonalcoholic steatohepatitis (NASH) in mice. However, the precise mechanism and preventive effects of adiponectin on NASH remain unclear. The aim of this study was to examine the effects of adiponectin on steatohepatitis using adiponectin‐knockout (KO) mice and adenovirus‐mediated adiponectin expression system.

Disturbed gastrointestinal motility and decreased interstitial cells of Cajal in diabetic db/db mice

Background and Aim:  Diabetes mellitus (DM) often causes gastrointestinal dysmotility. Interstitial cells of Cajal (ICC), which express c‐kit receptor tyrosine kinase (KIT), are considered the pacemaker cells for gastrointestinal movement. The present study was designed to determine the role of ICC in the pathogenesis of gastroenteropathy in type 2 DM.

The tetraspanin CD9 modulates epidermal growth factor receptor signaling in cancer cells

CD9 is a member of the tetraspanins, and has been shown to be involved in a variety of cellular activities such as migration, proliferation, and adhesion. In addition, it has been known that CD9 can associate with other proteins. Here we demonstrated the physical and functional association of CD9 with epidermal growth factor receptor (EGFR) on MKN‐28 cells. Double‐immunofluorescent staining and immunoprecipitation demonstrated the complex formation of CD9‐EGFR and CD9‐β1 integrin, and that both complexes are colocalized on the cell surface especially at the cell–cell contact site. Anti‐CD9 monoclonal antibody ALB6 induced a dotted or patch‐like aggregation pattern of both CD9‐EGFR and CD9‐β1 integrin. The internalization of EGFR after EGF‐stimulation was significantly enhanced by the treatment with ALB6. CD9 can associate with EGFR in hepatocellular carcinoma cells (HepG2/CD9) and Chinese hamster ovary cancer cells (CHO‐HER/CD9), which were transfected with pTJ/human EGFR/CD9. Furthermore expression of CD9 specifically attenuated EGFR signaling in CHO‐HER/CD9 cells through the down regulation of surface expression of EGFR. These results suggest that CD9 might have an important role that attenuates EGFR signaling. Therefore, CD9 not only associates EGFR but also a new regulator, which may affect EGF‐induced signaling in cancer cells. J. Cell. Physiol. 216: 135–143, 2008.

Surgical interventions for focal progression of advanced gastrointestinal stromal tumors during imatinib therapy.

BackgroundAlthough imatinib has shown high activity in the majority of patients with advanced gastrointestinal stromal tumors (GIST), it has become clear that secondary resistance appears during chronic therapy. The aim of this study was to retrospectively analyze the safety and prognostic effects of surgical interventions for focal progression during imatinib treatment.MethodsBetween January 2002 and May 2005, 16 patients who had focal lesions of secondary-resistant GIST to imatinib treatment (male/female, 12 : 4; median age, 62 years) underwent surgical interventions such as resection, radiofrequency ablation, and their combination.ResultsPostoperative complications, including liver abscess, bile leak, wound infection, and ileus were mostly mild, and the patients recovered with conservative therapy. There was no hospital death. The median time to progression (TTP) of all patients was 5.5 months, and only one patient died of the disease; the others are alive after a median follow up of 12.4 months. Patients with complete resections of resistant lesions (n = 7) showed significantly better median TTP than those with incomplete resections (n = 9; P = 0.014). The impact of curability on focal lesions with secondary resistance was mainly significant in patients with tumors of stomach origin (P = 0.013), and a smaller number (P = 0.014) and smaller size (P = 0.018) of resistant lesions. Overall survival was 100% at 1 year and 75% at 2 years.ConclusionOur study indicates that surgical interventions in patients with GIST resistant to imatinib therapy are efficacious when complete resections are performed, when the lesions are of gastric origin, when the number of lesions is lower, and when the lesions are a smaller size.

Cd9-mediated activation of the p46 Shc isoform leads to apoptosis in cancer cells

CD9, a member of the tetraspanin family, has been shown to be involved in a range of cellular activities, including migration, proliferation and adhesion, but the molecular mechanisms by which it mediates such events is unclear. Here, we found that anti-CD9 monoclonal antibody ALB6 inhibited cell proliferation, reduced cell viability and induced not only morphological changes specific to apoptosis but also molecular changes, as evidenced by TUNEL and annexin-V staining. For the possible mechanism of ALB6-induced apoptosis, ALB6 activated the c-Jun NH2-terminal kinase/stress-activated protein kinase (JNK/SAPK) and p38 mitogen-activated-protein kinase (MAPK) within 5-15 minutes, as well as caspase-3 within 24-48 hours. It is noteworthy that ALB6 induced tyrosine phosphorylation of the p46 Shc isoform specifically and that the overexpression of its dominant-negative form completely suppressed the ALB6-induced activation of JNK/SAPK, p38 MAPK and caspase-3, resulting in the inhibition of apoptotic cell death. These results suggest that CD9 might regulate apoptosis through the specialized signals in human cancer cell lines.

Gastric ESD under Heparin Replacement at High-Risk Patients of Thromboembolism Is Technically Feasible but Has a High Risk of Delayed Bleeding: Osaka University ESD Study Group

Objectives. Heparin replacement (HR) is often performed in patients with a high risk of thrombosis undergoing endoscopic procedures. However, information about the influence of HR is scarce. The aim of this study is to assess the clinical impact of HR for gastric endoscopic submucosal dissection (ESD). Methods. This is a retrospective study comprising approximately 1310 consecutive gastric neoplasms in 1250 patients, who underwent ESD in 5 institutes. We assessed the clinical findings and outcomes of ESD under HR, compared to ESD without HR as control. Results. A total of 24 EGC lesions in 24 patients were treated by ESD under HR. In the HR group, the complete en-bloc resection rate was 100%. The delayed bleeding rate was, however, higher in the HR group than in the controls (38% versus 4.6%). The timing of bleeding in the HR group was significantly later than in controls. In the control group, 209 patients discontinued antithrombotic therapy during perioperative period, and their delayed bleeding rate was not different from those without antithrombotic therapy (5.7% versus. 4.4%). A thromboembolic event was encountered in 1 patient under HR after delayed bleeding. Conclusion. ESD under HR is technically feasible but has a high risk of delayed bleeding.