Masahide Ebi

Tumor suppressor, AT motif binding factor 1 (ATBF1), translocates to the nucleus with runt domain transcription factor 3 (RUNX3) in response to TGF-β signal transduction

BACKGROUND AND AIMS AT motif binding factor 1 (ATBF1), a homeotic transcription factor, was identified as a tumor suppressor, and loss of heterozygosity at ATBF1 locus occurs frequently in gastric cancers. We previously showed that ATBF1 expression inversely correlated with the malignant character of gastric cancer and that ATBF1 enhanced the promoter activity of p21Waf1/Cip1. We also found that ATBF1 moves between cytoplasm and nucleus, but the precise mechanism of translocation is unknown. In this study, we investigated the mechanism of ATBF1 translocation to the nucleus with the runt domain transcription factor 3 (RUNX3) in cooperation with TGF-beta signal transduction. MATERIALS AND METHODS To analyze the expression of ATBF1 and RUNX3 in gastric cancer cells, we performed immunohistochemistry on 98 resected gastric cancer tissue samples and scored the nuclear staining intensity as grade 0 to grade 5. Co-immunoprecipitation (co-IP) of ATBF1 and RUNX3 was performed. Dual luciferase assays were performed by transfecting ATBF1 and RUNX3 with a p21Waf1/Cip1 reporter vector. To investigate the nuclear translocation of endogenous ATBF1 and RUNX3 in response to TGF-beta signal, we examined the subcellular localization of ATBF1 and RUNX3 in gastric cancer cells treated with recombinant TGF-beta1 using confocal laser scanning microscopy. RESULTS Strong immunohistochemical nuclear staining of ATBF1 was observed in 37 (37.8%) of the gastric cancer tissue samples, and RUNX3 nuclear staining was observed in 15 (15.3%). There was a statistically significant correlation between ATBF1 and RUNX3 nuclear localization (rs=0.433, p<0.001). Co-IP revealed a physical association between ATBF1 and RUNX3. ATBF1 and RUNX3 up-regulated p21Waf1/Cip1 promoter activity synergistically. In SNU16 gastric cancer cells, ATBF1 and RUNX3 were cytoplasmic before TGF-beta1 stimulation, but after 24h of TGF-beta1 stimulation, endogenous ATBF1 and RUNX3 translocated to the nucleus. CONCLUSION ATBF1 associates with RUNX3 and translocates to the nucleus in response to TGF-beta signal transduction and might function in the nucleus as tumor suppressor and transcriptional regulator.

Establishment of a long-term three-dimensional primary culture of mouse glandular stomach epithelial cells within the stem cell niche

Compared to the small intestine and colon, little is known about stem cells in the stomach because of a lack of specific stem cell markers and an in vitro system that allows long-term culture. Here we describe a long-term three-dimensional (3D) primary gastric culture system within the stem cell niche. Glandular stomach cells from neonatal mice cultured in collagen gel yielded expanding sphere-like structures for 3months. The wall of the gastrospheres consisted of a highly polarized epithelial monolayer with an outer lining of myofibroblasts. The epithelial cells showed a tall columnar cell shape, basal round nuclei, and mucus-filled cytoplasm as well as expression of MUC5AC, indicating differentiation into gastric surface mucous cells. These cells demonstrated the features of fully differentiated gastric surface mucous cells such as microvilli, junctional complexes, and glycogen and secretory granules. Fewer than 1% of cultured epithelial cells differentiated into enteroendocrine cells. Active proliferation of the epithelial cells and many apoptotic cells in the inner lumen revealed the rapid cell turnover in gastrospheres in vitro. This method enables us to investigate the role of signaling between cell-cell and epithelial-mesenchymal interactions in an environment that is extremely similar to the in vivo environment.

Blockage of angiotensin II type 1 receptor regulates TNF-α-induced MAdCAM-1 expression via inhibition of NF-κB translocation to the nucleus and ameliorates colitis

Mucosal vascular addressin cell adhesion molecule 1 (MAdCAM-1) is an important target in the treatment of inflammatory bowel disease (IBD). Recently, treatment of IBD with an antibody to alpha4beta7-integrin, a ligand for MAdCAM-1, has been an intense focus of research. Our aim was to clarify the mechanism by which MAdCAM-1 is regulated via angiotensin II type 1 receptor (AT1R), and to verify if AT1R might be a novel target for IBD treatment. The role of AT1R in the expression of MAdCAM-1 in SVEC (a murine high endothelial venule cell) and MJC-1 (a mouse colonic endothelial cell) was examined following cytokine stimulation. We further evaluated the effect of AT1R on the pathogenesis of immune-mediated colitis using AT1R-deficient (AT1R-/-) mice and a selective AT1R blocker. AT1R blocker significantly suppressed MAdCAM-1 expression induced by TNF-alpha, but did not inhibit phosphorylation of p38 MAPK or of IkappaB that modulate MAdCAM-1 expression. However, NF-kappaB translocation into the nucleus was inhibited by these treatments. In a murine colitis model induced by dextran sulfate sodium, the degree of colitis, judged by body weight loss, histological damage, and the disease activity index, was much milder in AT1R-/- than in wild-type mice. The expression of MAdCAM-1 was also significantly lower in AT1R-/- than in wild-type mice. These results suggest that AT1R regulates the expression of MAdCAM-1 under colonic inflammatory conditions through regulation of the translocation of NF-kappaB into the nucleus. Furthermore, inhibition of AT1R ameliorates colitis in a mouse colitis model. Therefore, AT1R might be one of new therapeutic target of IBD via regulation of MAdCAM-1.

TGFβ induces proHB-EGF shedding and EGFR transactivation through ADAM activation in gastric cancer cells

BACKGROUND AND AIMS Transforming growth factor-beta (TGFβ) is known to potently inhibit cell growth. Loss of responsiveness to TGFβ inhibition on cell growth is a hallmark of many types of cancer, yet its mechanism is not fully understood. Membrane-anchored heparin-binding EGF-like growth factor (proHB-EGF) ectodomain is cleaved by a disintegrin and metalloproteinase (ADAM) members and is implicated in epidermal growth factor receptor (EGFR) transactivation. Recently, nuclear translocation of the C-terminal fragment (CTF) of pro-HB-EGF was found to induce cell growth. We investigated the association between TGFβ and HB-EGF signal transduction via ADAM activation. MATERIALS AND METHODS The CCK-8 assay in two gastric cancer cell lines was used to determine the effect for cell growth by TGFβ. The effect of two ADAM inhibitors was also evaluated. Induction of EGFR phosphorylation by TGFβ was analyzed and the effect of the ADAM inhibitors was also examined. Nuclear translocation of HB-EGF-CTF by shedding through ADAM activated by TGFβ was also analyzed. EGFR transactivation, HB-EGF-CTF nuclear translocation, and cell growth were examined under the condition of ADAM17 knockdown. RESULT TGFβ-induced EGFR phosphorylation of which ADAM inhibitors were able to inhibit. TGFβ induced shedding of proHB-EGF allowing HB-EGF-CTF to translocate to the nucleus. ADAM inhibitors blocked this nuclear translocation. TGFβ enhanced gastric cancer cell growth and ADAM inhibitors suppressed this effect. EGFR phosphorylation, HB-EGF-CTF nuclear translocation, and cell growth were suppressed in ADAM17 knockdown cells. CONCLUSION HB-EGF-CTF nuclear translocation and EGFR transactivation from proHB-EGF shedding mediated by ADAM17 activated by TGFβ might be an important pathway of gastric cancer cell proliferation by TGFβ.

Multicenter, prospective trial of white-light imaging alone versus white-light imaging followed by magnifying endoscopy with narrow-band imaging for the real-time imaging and diagnosis of invasion depth in superficial esophageal squamous cell carcinoma.

BACKGROUND Magnifying endoscopy with narrow-band imaging (ME-NBI) has been used to estimate the invasion depth of superficial esophageal squamous cell carcinoma (SESCC), but the real diagnostic power of ME-NBI remains unclear because of few prospective studies. OBJECTIVES To evaluate whether ME-NBI adds additional information to white-light imaging (WLI) for the diagnosis of invasion depth of SESCC. DESIGN Multicenter, prospective trial using real-time imaging and diagnosis. SETTING Seven Japanese institutions. PATIENTS Fifty-five patients with SESCC were enrolled from June 2011 to October 2013, and the results for 49 lesions were analyzed. INTERVENTIONS Patients underwent primary WLI followed by ME-NBI, and reports of primary WLI (WLI alone) were completed before secondary ME-NBI (WLI followed by ME-NBI). To standardize diagnosis among examiners, this trial was started after achievement of a mean κ value≥.6 among 11 participating endoscopists. MAIN OUTCOME MEASUREMENTS Diagnosis of invasion depth by each tool was divided into cancer limited to the epithelium and the lamina propria mucosa and cancer invading beyond the muscularis mucosae (≥T1a-MM) and then collated with the final pathologic diagnosis by an independent pathologist blinded to the clinical data. RESULTS The accuracy of invasion depth in WLI alone and WLI followed by ME-NBI was 71.4% and 65.3% (P=.375), respectively. Sensitivity for ≥T1a-MM was 61.1% for both groups (P=1.000), and specificity for ≥T1a-MM was 77.4% for WLI alone and 67.7% for WLI followed by ME-NBI (P=.375). LIMITATION Open-label trial. CONCLUSIONS ME-NBI showed no additional benefit to WLI for diagnosis of invasion depth of SESCC. (University Hospital Network Clinical Trials Registry number: UMIN000005632.).

Association of Intestinal Microbiota with Metabolic Markers and Dietary Habits in Patients with Type 2 Diabetes

Background/Aims: Evidence suggests that intestinal microbiota, along with factors such as diet and host genetics, contributes to obesity, metabolic dysfunction and diabetes. Therefore, we examined the relationship between gut microbiota, blood metabolic markers, dietary habits and fecal short-chain fatty acids (SCFAs) in patients with type 2 diabetes mellitus (T2DM). Methods: Dietary habits, blood and fecal samples from 59 T2DM patients were recruited, and the association of intestinal microbiota with metabolic markers and dietary habits was analyzed. Results: Total energy intake was 1,692 ± 380 kcal/day. Carbohydrate, fat and protein intakes were 57.5 ± 5.2, 23.2 ± 5.3 and 13.2 ± 2.2%, respectively. Dietary habits - high carbohydrate, fat, and protein intake - were associated with increased counts of Clostridium clusters IV and XI and decreased counts of Bifidobacterium spp., order Lactobacillales and Clostridium cluster IV. Protein intake was negatively correlated with fecal acetate and total SCFAs. Total SCFAs, propionate and acetate were negatively correlated with blood insulin levels and the homeostasis model of insulin resistance. Conclusion: Diets low in protein and carbohydrates favor a healthy gut microbiome and improve glucose tolerance in T2DM patients, although further elucidation of the role of the gut microbiome could lead to better therapies and prophylaxes.

Magnifying Chromoendoscopy and Endoscopic Ultrasonography Measure Invasion Depth of Early Stage Colorectal Cancer With Equal Accuracy on the Basis of a Prospective Trial

BACKGROUND & AIMS Magnifying chromoendoscopy (MC) and endoscopic ultrasonography (EUS) are used to estimate the depth of colorectal cancer (CRC) invasion, but it is not clear which procedure is more accurate. We performed a prospective study to compare MC and EUS. METHODS A total of 70 patients with an early stage flat CRC lesion were enrolled at 6 institutions in Japan and randomly assigned to groups assessed by MC followed by EUS or EUS followed by MC. Results from MC and EUS measurements of 66 lesions were included in the final analysis. The invasion depth of each lesion was measured by each procedure and categorized as mucosal to slight submucosal (depth <1000 μm) or deep submucosal (depth ≥ 1000 μm); measurements were compared with the final diagnosis on the basis of the pathology analysis. All participating examiners achieved a mean κ value ≥ 0.6 for both MC and EUS before this trial. RESULTS MC and EUS each measured the depth of lesion invasion with 71.2% accuracy (correctly for 47 of 66 lesions). MC identified lesions with deep submucosal invasion with 74.2% sensitivity and 68.6% specificity, whereas EUS identified them with 67.7% sensitivity and 74.3% specificity. The differences between MC and EUS measurements did not differ significantly. However, MC required significantly shorter observation time than EUS (361.7 ± 164.5 seconds vs 451.2 ± 209.4 seconds, P = .002). CONCLUSIONS MC and EUS are equally accurate in estimating the invasion depth of early stage CRC lesions. However, neither procedure has sufficient diagnostic accuracy to be used as the standard. University Hospital Medical Network Clinical Trials Registry, Number: UMIN 000005085.

Nuclear translocation of the cytoplasmic domain of HB-EGF induces gastric cancer invasion

BackgroundMembrane-anchored heparin-binding epidermal growth factor-like growth factor (proHB-EGF) yields soluble HB-EGF, which is an epidermal growth factor receptor (EGFR) ligand, and a carboxy-terminal fragment of HB-EGF (HB-EGF-CTF) after ectodomain shedding. We previously reported that HB-EGF-CTF and unshed proHB-EGF which has the cytoplasmic domain of proHB-EGF (HB-EGF-C), translocate from the plasma membrane to the nucleus and regulate cell cycle after shedding stimuli. However, the significance of nuclear exported HB-EGF-C in human gastric cancer is unclear.MethodsWe investigated the relationship between intracellular localization of HB-EGF-C and clinical outcome in 96 gastric cancer patients treated with gastrectomy. Moreover, we established stable gastric cancer cell lines overexpressing wild-type HB-EGF (wt-HB-EGF) and mutated HB-EGF (HB-EGF-mC), which prevented HB-EGF-C nuclear translocation after shedding. Cell motility between these 2 gastric cancer cell lines was investigated using a transwell invasion assay and a wound healing assay.ResultsOf the 96 gastric cancer cases, HB-EGF-C immunoreactivity was detected in both the nucleus and cytoplasm in 19 cases (19.8 %) and in the cytoplasm only in 25 cases (26.0 %). The nuclear immunoreactivity of HB-EGF-C was significantly increased in stage pT3/4 tumors compared with pT1/2 tumors (T1/2 vs. T3/4: 11.1 % vs. 36.4 %, P < 0.01). The growth of wt-HB-EGF- and HB-EGF-mC-expressing cells significantly increased compared with control cells, but the growth of HB-EGF-mC-expressing cells was significantly decreased compared with wt-HB-EGF-expressing cells. Gastric cancer cell invasion obviously increased in wt-HB-EGF-expressing cells, but invasion in HB-EGF-mC-expressing cells showed a slight increase compared with control cells. Moreover, wt-HB-EGF overexpression increased the effectiveness of wound healing, but had no significant effect in HB-EGF-mC-expressing cells.ConclusionsBoth the function of HB-EGF as an EGFR ligand and a novel signal for HB-EGF-C nuclear translocation induce gastric cancer growth, whereas HB-EGF-C nuclear translocation independently plays a critical role in gastric cancer invasion. The present study demonstrated that HB-EGF-C nuclear translocation might be crucial in gastric cancer invasion. HB-EGF-C nuclear translocation may offer a prognostic marker and a new molecular target for gastric cancer therapy.

Oncolytic reovirus combined with trastuzumab enhances antitumor efficacy through TRAIL signaling in human HER2-positive gastric cancer cells

The human epidermal growth factor receptor 2 (HER2)-targeting agent, trastuzumab, is effective for HER2-overexpressing gastric cancer therapy. As oncolytic reovirus is currently undergoing clinical trials internationally, we wanted to explore whether combination therapy using trastuzumab and reovirus might provide a novel, more effective therapeutic option for gastric cancer. Cell proliferation and cell apoptosis were examined in vitro, while molecular analysis of pathways responsible for cell damage was examined using polymerase chain reaction array. Activation of the proteins related to apoptosis, cell growth and survival was detected by Western blotting. Mouse tumor xenograft models were used to examine antitumor activity in vivo. Reovirus sensitized HER2-overexpressing gastric cancer cells to undergo apoptosis. Both in vitro and in vivo studies provided evidence that the combination therapy is a more powerful modality against HER2-overexpressing gastric cancer cells than treatment using a single agent. Molecular analysis indicated that combination therapy induced significantly higher levels of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in cancer cells. Antibody against TRAIL strongly inhibited cell toxicity caused by the combined treatment. These data suggest that reovirus may augment trastuzumab-induced cytotoxicity in gastric cancer cells.

Annexin A2 regulates a disintegrin and metalloproteinase 17-mediated ectodomain shedding of pro-tumor necrosis factor-α in monocytes and colon epithelial cells.

Background:Understanding the mechanism of tumor necrosis factor (TNF)-&agr; shedding is important because TNF-&agr; triggers inflammatory bowel disease development. A disintegrin and metalloproteinase (ADAM) 17 is a key enzyme for the shedding of not only the type 1 membrane-anchored protein, amphiregulin, but also the type 2 protein, TNF-&agr;. However, the detailed mechanism by which ADAM17 cleaves type 1 and 2 membrane-anchored proteins is unclear. Annexin (ANX) A2 is involved in ADAM17-mediated amphiregulin shedding. In this study, we examined whether ANX A2 is involved in TNF-&agr; shedding. Methods:We prepared U937, HT29, and HCT116 cells overexpressing alkaline phosphatase (AP)-tagged proTNF-&agr; and depleted ADAM17 and ANX A2. We assessed TNF-&agr; release and shedding by measuring the TNF-&agr; release concentration and AP activities in conditioned media after interleukin-1&bgr; or 12-O-tetradecanoylphorbol-13-acetate (TPA) stimulation by enzyme-linked immunosorbent assay and AP assay, respectively. A direct association of ANX A2 with ADAM17 was examined with immunoprecipitation and Western blotting. Results:Enzyme-linked immunosorbent assay and AP assay showed interleukin-1&bgr;–induced TNF-&agr; shedding in HCT116 and HT29 cells and TPA-induced TNF-&agr; release in U937 cells. KB-R7785 and ADAM17 depletion significantly blocked TNF-&agr; shedding by TPA. ANX A2 depletion significantly inhibited TNF-&agr; shedding by interleukin-1&bgr; and TPA. In contrast, ANX A2 depletion did not abrogate ADAM17-mediated amphiregulin and heparin-binding epidermal growth factor-like growth factor shedding. ANX A2 was directly associated with ADAM17. Conclusions:ANX A2 was closely associated with ADAM17 and played an important role in TNF-&agr; shedding by TPA. Inhibition of ANX A2 might be a new therapeutic strategy for prevention of TNF-&agr; shedding during inflammatory bowel disease inflammation.