Institute of Digestive Disease

Hong Kong, China

Institute of Digestive Disease

Hong Kong, China
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Wang S.,Institute of Digestive Disease | Cheng Y.,Chinese University of Hong Kong | Du W.,Institute of Digestive Disease | Du W.,Shanghai JiaoTong University | And 9 more authors.
Gut | Year: 2013

Objective: Zinc-finger protein 545 (ZNF545) is a member of the family of Krüppel-associated box-containing zinc-finger proteins. The aim of this study was to clarify its biological function as a tumour suppressor in gastric cancer. Design: The biological function of ZNF545 was determined by cell growth and apoptosis assays. The ZNF545 target signal pathway was identified by promoter luciferase assay, northern blot, run-on transcription assay, chromatin immunoprecipitation and coimmunoprecipitation assays. The clinical application of ZNF545 was assessed in primary gastric cancers. Results: ZNF545 was silenced or reduced in 16 out of 18 gastric cancer cell lines by promoter hypermethylation. Restoration of ZNF545 expression in gastric cancer cell lines suppressed cell proliferation and induced apoptosis. These effects of ZNF545 were attributed to inhibition of ribosomal RNA (rRNA) transcription. Inhibition of rRNA transcription by ZNF545 was further revealed to be associated with direct ribosomal DNA (rDNA) promoter binding, recruitment of the corepressor, heterochromatin protein 1β, and reduction of trimethylated histone H3 at the Lys4 residue at the rDNA locus. ZNF545 methylation was detected in 51.9% (41/79) of gastric cancer tissues, 27.0% (20/74) of adjacent non-tumour gastric tissues (p=0.001), but none of 20 normal controls. Multivariate analysis revealed that patients with ZNF545 methylation had a significant decrease in overall survival. Kaplan-Meier survival curves showed that ZNF545 methylation was significantly associated with shortened survival in patients with stage I-II gastric cancer. Conclusions: ZNF545 acts as a functional tumour suppressor in gastric cancer by inhibiting rRNA transcription. Its methylation at early stages of gastric carcinogenesis is an independent prognostic factor.

Du W.,Institute of Digestive Disease | Du W.,Shanghai JiaoTong University | Wang S.,Institute of Digestive Disease | Zhou Q.,Chinese University of Hong Kong | And 8 more authors.
Oncogene | Year: 2013

Using genome-wide promoter methylation analysis, we identified a disintegrin-like and metalloprotease with thrombospondin type 1 motif 9 (ADAMTS9) is methylated in cancer. We aim to clarify its epigenetic inactivation, biological function and clinical implication in gastric cancer. ADAMTS9 was silenced in 6 out of 8 gastric cancer cell lines. The loss of ADAMTS9 expression was regulated by promoter hypermethylation and could be restored by demethylation agent. Ectopic expression of ADAMTS9 in gastric cancer cell lines (AGS, BGC823) inhibited cell growth curve in both the cell lines (P<0.0001), suppressed colony formation (P<0.01) and induced apoptosis (P<0.001 in AGS, P<0.01 in BGC823). Moreover, conditioned culture medium from ADAMTS9-transfected cell lines significantly disrupted the human umbilical vein endothelial cell tube formation capacity on Matrigel (P<0.01 in AGS, P<0.001 in BGC823). The in vivo growth of ADAMTS9 cells in nude mice was also markedly diminished after stable expression of ADAMTS9 (P<0.001). On the other hand, ADAMTS9 knockdown promoted cell proliferation (P<0.001). We further revealed that ADAMTS9 inhibited tumor growth by blocking activation of Akt and its downstream target the mammalian target of rapamycin (mTOR). ADAMTS9 also reduced phosphorylation of mTOR downstream targets p70 ribosomal S6 kinase, eIF4E-binding protein and downregulated hypoxia-inducible factor-1α. Therefore, this is the first demonstration that ADAMTS9 is a critical tumor suppressor of gastric cancer progression at least in part through suppression of oncogenic AKT/mTOR signaling. Moreover, promoter methylation of ADAMTS9 was detected in 29.2% (21/72) of primary gastric tumors. Multivariate analysis showed that patients with ADAMTS9 methylation had a poorer overall survival (relative risk (RR)=2.788; 95% confidence interval, 1.474-5.274; P=0.002). Kaplan-Meier survival curves showed that ADAMTS9 methylation was significantly associated with shortened survival in gastric cancer patients (P=0.001, log-rank test). In conclusion, ADAMTS9 acts as a functional tumor suppressor in gastric cancer through inhibiting oncogenic AKT/mTOR signaling pathway. Methylation of ADAMTS9 is an independent prognostic factor of gastric cancer. © 2013 Macmillan Publishers Limited.

Wu C.W.,Institute of Digestive Disease | Wu C.W.,CUHK Shenzhen Research Institute | Ng S.C.,Institute of Digestive Disease | Dong Y.,Institute of Digestive Disease | And 9 more authors.
Clinical Cancer Research | Year: 2014

Purpose: Detecting microRNA (miRNA) in stool is a novel approach for colorectal cancer (CRC) screening. This study aimed to identify stool-based miRNA as noninvasive biomarkers for detection of CRC and adenoma. Experimental Design: A miRNA expression array covering 667 human miRNAs was performed on five pairs of CRC and two pairs of advanced adenoma tissues. The most upregulated miRNAs were validated in 40 pairs of CRC tissues, 16 pairs of advanced adenoma tissues, and 424 stool samples, including 104 CRCs, 169 adenomas, 42 inflammatory bowel diseases (IBD), and 109 healthy controls. miRNA levels were followed-up after removal of lesions. Results: In an array analysis, miR-31 and miR-135b were the most upregulated miRNAs in CRC and advanced adenoma as compared with their adjacent normal tissues (>13-fold increase). In stool samples, level of miR-135b was significantly higher in subjects with CRC (P < 0.0001) or adenomas (P < 0.0001), but not in patients with IBD compared with controls. miR-135b showed a significant increasing trend across the adenoma to cancer sequence (P < 0.0001). Levels of miR-31 were not significantly different among groups. The sensitivity of stool mR-135b was 78% for CRC, 73% for advanced adenoma, and 65% for any adenoma, respectively, with a specificity of 68%. No significant difference in the miR-135b level was found between proximal and distal colorectal lesions. Stool miR-135b dropped significantly upon removal of CRC or advanced adenoma (P < 0.0001). Conclusion: Stool-based miR-135b can be used as a noninvasive biomarker for the detection of CRC and advanced adenoma. ©2014 AACR.

Kang W.,Sir o Center For Cancer | Kang W.,Institute of Digestive Disease | Tong J.H.M.,Sir o Center For Cancer | Tong J.H.M.,Institute of Digestive Disease | And 17 more authors.
Clinical Cancer Research | Year: 2011

Purpose: Yes-associated protein 1 (YAP1) is a multifunctional protein that can interact with different transcription factors to activate gene expression. The role of YAP1 in tumorigenesis is unclear. We aimed to investigate the functional role of YAP1 in tumorigenesis of gastric cancer. Experimental Design: YAP1 expresson in gastric adenocarcinoma was evaluated. The biological function was determined by proliferation assay, colony formation, cell invasion, and flow cytometric analysis through knocking down or ectopic expressing YAP1 in gastric cancer cell lines coupled with in vivo study. The possible downstream effectors of YAP1 were investigated by expression microarray. Results: YAP1 protein expression was upregulated in gastric cancer. Nuclear accumulation of YAP1 was associated with poor disease-specific survival (P = 0.021), especially in patients with early-stage diseases (P < 0.001). Knockdown YAP1 resulted in a significant reduction in proliferation, anchoragedependent colony formation, cell invasion, and cell motility. Ectopic YAP1 expression promoted anchorage-independent colony formation, induced a more invasive phenotype, and accelerated cell growth both in vitro and in vivo. Microarray analysis highlighted the alteration of MAPK (mitogenactivated protein kinase) pathway by YAP1. We confirmed a constitutive activation of RAF/MEK/ERK (extracellular signal-regulated kinase) in YAP1-expressing MKN45 cells and further showed that YAP1 enhanced serum/epidermal growth factor-induced c-Fos expression in gastric cancer cells. Conclusions: Our findings supported that YAP1 exhibits oncogenic property in gastric cancer. We provided the first evidence that YAP1 exerted the oncogenic function by enhancing the capacity to activate the early-response gene pathway. YAP1 could be a prognostic biomarker and potential therapeutic target for gastric cancer. © 2011 American Association for Cancer Research.

Tsang W.P.,Li Ka Shing Institute of Health science | Ng E.K.O.,Institute of Digestive Disease | Ng S.S.M.,Chinese University of Hong Kong | Jin H.,Institute of Digestive Disease | And 3 more authors.
Carcinogenesis | Year: 2010

H19 is an imprinted oncofetal non-coding RNA recently shown to be the precursor of miR-675. The pathophysiological roles of H19 and its mature product miR-675 to carcinogenesis have, however, not been defined. By quantitative reverse transcription-polymerase chain reaction, both H19 and miR-675 were found to be upregulated in human colon cancer cell lines and primary human colorectal cancer (CRC) tissues compared with adjacent noncancerous tissues. Subsequently, the tumor suppressor retinoblastoma (RB) was confirmed to be a direct target of miR-675 as the microRNA suppressed the activity of the luciferase reporter carrying the 3′-untranslated region of RB messenger RNA that contains the miR-675-binding site. Suppression of miR-675 by transfection with anti-miR-675 increased RB expression and at the same time, decreased cell growth and soft agar colony formation in human colon cancer cells. Reciprocally, enhanced miR-675 expression by transfection with miR-675 precursor decreased RB expression, increased tumor cell growth and soft agar colony formation. Moreover, the inverse relationship between the expressions of RB and H19/miR-675 was also revealed in human CRC tissues and colon cancer cell lines. Our findings demonstrate that H19-derived miR-675, through downregulation of its target RB, regulates the CRC development and thus may serve as a potential target for CRC therapy. © The Author 2009. Published by Oxford University Press. All rights reserved. For Permissions, please email:

Yu J.,Institute of Digestive Disease | Shen B.,Institute of Digestive Disease | Chu E.S.H.,Institute of Digestive Disease | Teoh N.,Australian National University | And 10 more authors.
Hepatology | Year: 2010

Although peroxisome proliferator-activated receptor gamma (PPARγ) agonist have been shown to inhibit hepatocellular carcinoma (HCC) development, the role of PPARγ in hepatocarcinogenesis remains unclear. We investigated the therapeutic efficacy of PPARγ against HCC. PPARγ-deficient (PPARγ+/-) and wild-type (PPARγ+/+) littermates were used in a diethylnitrosamine (DEN)-induced HCC model and treated with PPARγ agonist (rosiglitazone) or the vehicle alone for 8 months. The effects of PPARγ on HCC cell growth and apoptosis were examined using PPARγ-expressing adenovirus (Ad-PPARγ). PPARγ+/- mice were more susceptible to DEN-induced HCC than PPARγ+/+ mice (94% versus 62%, P < 0.05), and rosiglitazone significantly reduced the incidence of HCC in PPARγ+/+ mice (vehicle 62% versus treatment 24%, P < 0.01), but not in PPARγ +/- mice, indicating that PPARγ suppresses hepatocellular carcinogenesis. A pronounced expression of PPARγ was observed in a HCC cell line (Hep3B) infected with Ad-PPARγ. Such induction markedly suppressed HCC cell viability (P < 0.01). Further, Hep3B infection with Ad-PPARγ revealed a decreased proportion of cells in S-phase (12.92% versus 11.58%, P < 0.05), with arrest at G2/M phase (38.2% versus 55.68%, P < 0.001), and there was concomitant phosphorylation of the key G2/M phase inhibitors cdc25C and cdc2. PPARγ overexpression increased cell apoptosis (21.47% versus 35.02%, P < 0.01), mediated by both extrinsic (Fas and tumor necrosis factor-α) and intrinsic (caspase-9, caspase-3, caspase-7, and poly[ADP-ribose] polymerase) pathways. Moreover, PPARγ directly induced a putative tumor suppressor gene, growth differentiation factor-15. Conclusion: Loss of one PPARγ allele is sufficient to enhance susceptibility to HCC. PPARγ suppresses tumor cell growth through reducing cell proliferation and inducing G2/M phase arrest, apoptosis, and up-regulating growth differentiation factor-15. Thus, PPARγ acts as a tumor-suppressor gene in the liver. Copyright © 2010 by the American Association for the Study of Liver Diseases.

Ajamieh H.,Australian National University | Farrell G.,Australian National University | Wong H.J.,Australian National University | Yu J.,Institute of Digestive Disease | And 3 more authors.
Journal of Gastroenterology and Hepatology (Australia) | Year: 2012

Background and Aim: Steatosis accentuates the severity of hepatic ischemia-reperfusion injury (IRI). 3-Hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors ("statins") protect the heart and brain against post-ischemic injury, without necessarily lowering serum cholesterol. We tested whether 10-day or 1-day atorvastatin administration protects livers with fatty change or non-alcoholic steatohepatitis (NASH) against IRI. Methods: Mice with dietary or genetic simple steatosis (SS) or NASH were subjected to 60min of partial hepatic ischemia/24-h reperfusion, with/without atorvastatin administered with food (5mg/kg body weight) for 10days, or injected intravenously (5mg/kg) 24h before ischemia. Liver injury, Toll-like receptor-4 (TLR4), cytokines/chemokines, endothelial nitric oxide synthase (eNOS), activation and thromboxane B2 production were determined. Results: Atorvastatin conferred 70-90% hepatic protection against IRI in obese animals with SS or NASH, in which IRI was accentuated twofold to fivefold. IRI markedly upregulated TLR4 and activated nuclear factor-κB (NF-κB); atorvastatin abrogated these effects, as well as activating eNOS. Atorvastatin dampened the post-ischemic induction of thromboxane B2, macrophage inflammatory protein-1a, monocyte chemotactic protein-1, tumor necrosis factor-α, interleukin (IL)-12 p40, γ-interferon, IL-6, and adhesion molecules (vascular cell adhesion molecule-1, E-selectin, vascular endothelial-cadherin), and reduced macrophage and neutrophil recruitment. There was no reduction in serum cholesterol that could explain these effects, and hepatic cholesterol was normal in these mice. A single 24-h injection of atorvastatin conferred equivalent hepatoprotection. Conclusion: Statins exert major hepatoprotection against IRI in lean, fatty, and NASH livers that is not due to cholesterol removal. Rather, statins downregulate TLR4 to prevent NF-κB activation, with resultant suppression of adhesion molecules, chemokines/cytokines, and thromboxane B2 production. Short-term statin treatment is an effective, readily-available preventive agent against hepatic IRI, irrespective of obesity and fatty liver disease. © 2012 Journal of Gastroenterology and Hepatology Foundation and Blackwell Publishing Asia Pty Ltd.

Chiu P.W.Y.,Institute of Digestive Disease | Wai Ng E.K.,Institute of Digestive Disease | Teoh A.Y.B.,Institute of Digestive Disease | Lam C.C.H.,Institute of Digestive Disease | And 2 more authors.
Gastrointestinal Endoscopy | Year: 2010

Background: Gastrojejunal anastomosis is commonly performed for palliative management of malignant gastric outlet obstruction and bariatric surgery. Natural orifice transluminal endoscopic surgery revolutionized the surgical approach to intra-abdominal surgery. This study explored the possibility of performing gastrojejunostomy (GJ) by using a hybrid natural orifice transluminal endoscopic surgery approach. Objective: To develop a surgical technique for the performance of transgastric endoscopic GJ (TGEJ) in a porcine model. Design: Prospective series of animal experiments. Setting: University hospital animal laboratory. Animals: Thirteen female domestic pigs. Interventions: With the animals under general anesthesia, the endoscope is passed through the gastrotomy and a segment of small bowel is retrieved into the stomach. An enterotomy is then created, and an EndoGIA stapler is introduced through an intragastric port and passed between the small bowel and stomach wall. A GJ is formed after firing of the EndoGIA stapler. The pigs are allowed to resume their diet 1 day after the operation and are allowed to survive for 2 weeks before they are euthanized. The patency of the GJ is confirmed with a repeat endoscopy, contrast study, and postmortem examination. Results: A total of 13 TEGJs were performed, 11 of which were successful. The mean operative time was 53.6 ± 45.7 minutes. The mean time for gastrotomy was 4.7 minutes, and that for GJ was 42.5 minutes. One TEGJ was converted to open surgery because of malpositioning of the intragastric port, and the other failed because the enterotomy was too extensive. Ten of 11 pigs survived for 2 weeks, and endoscopic examination with contrast study confirmed that all the gastrojejunostomies were patent. On postmortem examination, the average size of the GJ was 30 mm. Limitations: The length between duodenojejunal flexure and the site chosen to perform the GJ could not be determined. Conclusions: TEGJ is technically feasible with a patent and sizable anastomosis. © 2010 American Society for Gastrointestinal Endoscopy.

Yu J.,Institute of Digestive Disease | Chu E.S.H.,Institute of Digestive Disease | Wang R.,Institute of Digestive Disease | Wang S.,Institute of Digestive Disease | And 5 more authors.
Gastroenterology | Year: 2010

Background & Aims: Heme oxygenase-1 (HO-1), an antioxidant defense enzyme, has been shown to protect against oxidant-induced tissue injury. We investigated the role of HO-1 in nutritional steatohepatitis in vitro and in vivo. Methods: AML-12 hepatocytes were cultured in methionine- and choline-deficient (MCD) medium. Cells were transfected with an adenovirus vector that expressed HO-1 (Ad-HO-1) or incubated with the HO-1 inducer hemin or the HO-1 inhibitor stannic mesoporphyrin for 24 hours. C57BL6 mice and db/db mice were fed MCD or control diets, with or without hemin, for up to 4 weeks. Results: AML-12 cells exposed to MCD medium developed significant steatosis, increased release of alanine aminotransferase, and showed signs of oxidative injury. Incubation with hemin induced HO-1 protein, suppressed steatosis, and reduced levels of alanine aminotransferase and lipid peroxidation. A comparable effect was observed in cells transfected with Ad-HO-1, whereas incubation of these cells with stannic mesoporphyrin completely abolished the Ad-HO-1- or hemin-mediated protection of hepatocytes. Mice injected with hemin significantly attenuated MCD-induced steatohepatitis and increased HO-1 protein and activity. This effect was associated with up-regulation of antioxidant chaperones and enzymes, down-regulation of proinflammatory cytokines, and up-regulation of the anti-inflammatory interleukin-22. Moreover, the reduction in steatosis caused by hemin was affected by up-regulation of peroxisome proliferator-activated receptor-α and by down-regulation of sterol regulatory element binding protein-1c. Conclusions: HO-1 can interrupt progression of nutritional steatohepatitis by inducing an antioxidant pathway, suppressing production of cytokines, and modifying fatty acid turnover. Induction of HO-1 might provide a new approach for treatment of steatohepatitis. © 2010 AGA Institute.

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