Purpose: To correlate spin-lattice relaxation time in the rotating frame (T1ρ) measurements with degree of liver fibrosis in a rat model. Materials and Methods: The protocols and procedures were approved by the local Animal Experimentation Ethics Committee. Liver fibrosis was induced with biliary duct ligation (BDL). Two studies, 1 month apart, were performed with a 3-T clinical imager. The first study involved longitudinal magnetic resonance (MR) imaging follow-up of BDL rats (n = 8) and control rats (n = 4) on days 8, 15, 21, and 29 after BDL. The second study involved MR imaging of another group of BDL and control rats (n = 5 for each) on days 24 and 38 after BDL. Hematoxylin-eosin and picrosirius red staining were performed in liver specimens from days 8, 15, 24, and 38 after BDL. Repeated-measures analysis of variance was used, and treatment groups were compared (Bonferroni adjustment). Results: On day 8, there were proliferation of bile duct and inflammatory cell infiltration around portal triads. While there was overlap, BDL rats (n = 8) demonstrated higher mean liver T1ρ values than did control rats(n = 4) on day 8 (46.7 msec ± 2.9 [standard deviation] vs 44.7 msec ± 1.2, P =.4). On day 15, BDL rats demonstrated liver fibrosis with a background of inflammatory infiltration. On day 15, mean T1ρ values in BDL rats could be largely separated from those in control rats (52.6 msec ± 6.0 vs 43.8 msec ± 1.5, P =.02). On day 24, BDL rats had liver T1ρ values 23.5% higher than in control rats (n = 5 for each group, P =.0007). Histomorphometric analysis showed that collagen content increased after surgery from days 8 to 24 (n = 6 for each group, P<.0001), with no further increase between days 24 and 38 (n = 6 for each group, P>.99). Conclusion: In this model, liver fibrosis was detected with T1ρ MR imaging; the degree of fibrosis was correlated with degree of increase in T1ρ measurements. © RSNA, 2011.

Yixiang Wáng    Jing Yuan    Eagle Chu    Minnieyy Go    Huang Hua    Anil tejbhan Ahuja    沈祖堯     Jun Yu   

Radiology

2011

Enhancer of zeste homolog 2 (EZH2) is the catalytic subunit of the Polycomb-repressive complex 2 (PRC2) that represses gene transcription through histone H3 lysine 27 trimethylation (H3K27me3). Although EZH2 is abundantly present in various cancers, the molecular consequences leading to oncogenesis remain unclear. Here, we show that EZH2 concordantly silences the Wnt pathway antagonists operating at several subcellular compartments, which in turn activate Wnt/β-catenin signaling in hepatocellular carcinomas (HCC). Chromatin immunoprecipitation promoter array and gene expression analyses in HCCs revealed EZH2 occupancy and reduced expression of Wnt antagonists, including the growth-suppressive AXIN2, NKD1, PPP2R2B, PRICKLE1, and SFRP5. Knockdown of EZH2 reduced the promoter occupancy of PRC2, histone deacetylase 1 (HDAC1), and H3K27me3, whereas the activating histone marks were increased, leading to the transcriptional upregulation of the Wnt antagonists. Combinatorial EZH2 and HDAC inhibition dramatically reduced the levels of nuclear β-catenin, T-cell factor-dependent transcriptional activity, and downstream pro-proliferative targets CCND1 and EGFR. Functional analysis revealed that downregulation of EZH2 reduced HCC cell growth, partially through the inhibition of β-catenin signaling. Conversely, ectopic overexpression of EZH2 in immortalized hepatocytes activated Wnt/β-catenin signaling to promote cellular proliferation. In human HCCs, concomitant overexpression of EZH2 and β-catenin was observed in one-third (61/179) of cases and significantly correlated with tumor progression. Our data indicate that EZH2-mediated epigenetic silencing contributes to constitutive activation of Wnt/β-catenin signaling and consequential proliferation of HCC cells, thus representing a novel therapeutic target for this highly malignant tumor. ©2011 AACR.

Alfred Cheng    Lau Suki Shuk-Kei    Yangchao Chen    Yutaka Kondo    Li May S.    Feng Hai    Arthur ka keung Ching    Kinfai Cheung    Wong Hoi Kin    Tong Joanna H.    Hongchuan Jin    Kwongwai Choy    Jun Yu    Kafai To    王昭春    Huang Tim H.-M.    沈祖堯    

Cancer Research

2011

TGF-β/Smad3 signaling promotes fibrosis, but the development of therapeutic interventions involving this pathway will require the identification and ultimate targeting of downstream fibrosis-specific genes. In this study, using a microRNA microarray and real-time PCR, wild-type mice had reduced expression of miR-29 along with the development of progressive renal fibrosis in obstructive nephropathy. In contrast, Smad3 knockout mice had increased expression of miR-29 along with the absence of renal fibrosis in the same model of obstruction. In cultured fibroblasts and tubular epithelial cells, Smad3 mediated TGF-β-induced downregulation of miR-29 by binding to the promoter of miR-29. Furthermore, miR-29 acted as a downstream inhibitor and therapeutic microRNA for TGF-β/Smad3-mediated fibrosis. In vitro, overexpression of miR-29b inhibited, but knockdown of miR-29 enhanced, TGF-β-induced expression of collagens I and III by renal tubular cells. Ultrasound-mediated gene delivery of miR-29b either before or after established obstructive nephropathy blocked progressive renal fibrosis. In conclusion, miR-29 is a downstream inhibitor of TGF-β/Smad3-mediated fibrosis and may have therapeutic potential for diseases involving fibrosis. Copyright © 2011 by the American Society of Nephrology.

Qin Wei    Arthurck Chung    Xiaoru Huang    Xiaoming Meng    David Hui    Cheukman Yu    沈祖堯     Huiyao Lan   

Journal of the American Society of Nephrology

2011

Hepatocellular carcinoma (HCC) is the fifth most common cancer worldwide. It is more prevalent in men than women. Related to this, recent genetic studies have revealed a causal role for androgen receptor (AR) in hepatocarcinogenesis, but the underlying molecular mechanism remains unclear. Here, we used genome-wide location and functional analyses to identify a critical mediator of AR signaling - cell cycle-related kinase (CCRK) - that drives hepatocarcinogenesis via a signaling pathway dependent on β-catenin and T cell factor (TCF). Ligand-bound AR activated CCRK transcription and protein expression via direct binding to the androgen- responsive element of the CCRK promoter in human HCC cell lines. In vitro analyses showed that CCRK was critical in human cell lines for AR-induced cell cycle progression, hepatocellular proliferation, and malignant transformation. Ectopic expression of CCRK in immortalized human liver cells activated β-catenin/TCF signaling to stimulate cell cycle progression and to induce tumor formation, as shown in both xenograft and orthotopic models. Conversely, knockdown of CCRK decreased HCC cell growth, and this could be rescued by constitutively active β-catenin or TCF. In primary human HCC tissue samples, AR, CCRK, and β-catenin were concordantly overexpressed in the tumor cells. Furthermore, CCRK overexpression correlated with the tumor staging and poor overall survival of patients. Our results reveal a direct AR transcriptional target, CCRK, that promotes hepatocarcinogenesis through the upregulation of β-catenin/TCF signaling.

Feng Hai    Alfred Cheng    Tsang Daisy Pui-Fong    Li May S.    Minnieyy Go    Yuesun Cheung    Zhao Guijun    Samuel sai ming Ng    Lin Marie C.M.    于俊    Paul Lai    Kafai To    沈祖堯    

Journal of Clinical Investigation

2011

Human norovirus (hNoV) remains refractory to propagation in cell culture systems. We believe that knowing the exact cell type that hNoV targets will provide important insights into culturing the virus. By the use of an in vitro whole-virus binding assay, the hNoV genogroup II genotype 4 Sakai variant was found to bind predominantly to cells of the lamina propria and Brunner's glands, but not to those of the luminal epithelial surface, of human duodenum tissue. Our findings, together with accumulating evidence reported elsewhere, suggest that hNoV may display tropism to nonepithelial cells, which is distinct from observations of other human enteric pathogens. © 2011, American Society for Microbiology.

陈子蔚    Ho Wing-Shan    沈祖堯    

Journal of Virology

2011

赵伟仁    沈祖堯    

Gastrointestinal Endoscopy

2011

We investigated the association of Interleukin (IL)-6-6331 polymorphisms with susceptibility to gastric cancer in 375 patients with gastric cancer and 386 age-and gender-matched healthy controls. After adjustment for the potential confounding effects of gender and age, IL-6-6331TC genotype was associated with a decreased risk of gastric cancer compared with the CC genotype. Further stratification analyses indicated that the protective effect of TC genotype was also observed in poorly differentiated gastric cancer, noncardia gastric cancer, and intestinal-type gastric cancer, respectively. These results suggest that the IL-6-6331 polymorphism is involved in susceptibility to developing gastric cancer. © 2011 Informa Healthcare USA, Inc.

Jun Yu    Jia Yanhong    Kinfai Cheung    曾志荣    Linwei Tian    Shiyan Wang    Pinjin Hu    沈祖堯    

Cancer Investigation

2011

Background: PRDM (PRDI-BF1 and RIZ domain containing) proteins are zinc finger proteins involved in multiple cellular regulations by acting as epigenetic modifiers. We studied a recently identified PRDM member PRDM5 for its epigenetic abnormality and tumor suppressive functions in multiple tumorigeneses. Methodology/Principal Findings: Semi-quantitative RT-PCR showed that PRDM5 was broadly expressed in human normal tissues, but frequently silenced or downregulated in multiple carcinoma cell lines due to promoter CpG methylation, including 80% (4/5) nasopharyngeal, 44% (8/18) esophageal, 76% (13/17) gastric, 50% (2/4) cervical, and 25% (3/12) hepatocellular carcinoma cell lines, but not in any immortalized normal epithelial cell lines. PRDM5 expression could be restored by 5-aza-2′-deoxycytidine demethylation treatment in silenced cell lines. PRDM5 methylation was frequently detected by methylation-specific PCR (MSP) in multiple primary tumors, including 93% (43/46) nasopharyngeal, 58% (25/43) esophageal, 88% (37/42) gastric and 63% (29/46) hepatocellular tumors. PRDM5 was further found a stress-responsive gene, but its response was impaired when the promoter was methylated. Ectopic PRDM5 expression significantly inhibited tumor cell clonogenicity, accompanied by the inhibition of TCF/β-catenin-dependent transcription and downregulation of CDK4, TWIST1 and MDM2 oncogenes, while knocking down of PRDM5 expression lead to increased cell proliferation. ChIP assay showed that PRDM5 bound to its target gene promoters and suppressed their transcription. An inverse correlation between the expression of PRDM5 and activated β-catenin was also observed in cell lines. Conclusions/Significance: PRDM5 functions as a tumor suppressor at least partially through antagonizing aberrant WNT/β-catenin signaling and oncogene expression. Frequent epigenetic silencing of PRDM5 is involved in multiple tumorigeneses, which could serve as a tumor biomarker. © 2011 Shu et al.

Xingsheng Shu    Hua Geng    Li Li-Li    Jianming Ying    Chunhong Ma    Wang Yajun    Poon Fan Fong    Xian Wang    Ying Ying    Winnie Yeo    Srivastava Gopesh    George Tsao    Jun Yu    沈祖堯     Shi Huang    Anthony Chan    Qian Tao   

PLoS ONE

2011

Objective: Non-alcoholic fatty liver disease (NAFLD) is the hepatic manifestation of metabolic syndrome and is associated with cardiovascular risk. The aim of this study was to determine the role of fatty liver in predicting coronary artery disease and clinical outcomes in patients undergoing coronary angiogram. Methods: This was a prospective cohort study carried out in a University hospital. Consecutive patients who underwent coronary angiogram had ultrasound screening for fatty liver. Significant cardiovascular disease was defined as ≥50% stenosis in at least one coronary artery. The primary outcome was a composite end point comprising cardiovascular deaths, non-fatal myocardial infarction and the need for further coronary intervention during prospective follow-up. Results: Among 612 recruited patients, 356 (58.2%) had fatty liver by ultrasonography, 318 (52.0%) had elevated serum alanine aminotransferase and 465 (76.0%) had significant coronary artery disease. Coronary artery disease occurred in 84.6% of patients with fatty liver and 64.1% of those without fatty liver (p<0.001). After adjusting for demographic and metabolic factors, fatty liver (adjusted OR 2.31; 95% CI 1.46 to 3.64) and alanine aminotransferase level (adjusted OR 1.01; 95% CI 1.00 to 1.02) remained independently associated with coronary artery disease. At a mean follow-up of 87622 weeks, 30 (10.0%) patients with fatty liver and 18 (11.0%) patients without fatty liver reached the composite clinical end point (p=0.79). Conclusions: In patients with clinical indications for coronary angiogram, fatty liver is associated with coronary artery disease independently of other metabolic factors. However, fatty liver cannot predict cardiovascular mortality and morbidity in patients with established coronary artery disease.

Vincent Wong    Grace Wong    Gabriel Yip    Lo Angeline Oi-Shan    Limquiaco Jenny L.    Winnie cw Chu    Angel mei ling Chim    Cheukman Yu    于俊    Francis Chan    沈祖堯     Henry lik yuen Chan   

Gut

2011

In a cohort of hospitalized adults with seasonal influenza A in Hong Kong, viral RNA was frequently (47%) detected in stool specimens. Viable virus was rarely isolated. Viral RNA positivity had little correlation with gastrointestinal symptoms and outcomes. In vitro studies suggested low potential for seasonal influenza viruses to cause direct intestinal infections.

陈子蔚    李礼舜    Paul Chan    Kafai To    Rity Wong    Ho Wing-Shan    Karry Ngai    沈祖堯    

Emerging Infectious Diseases

2011