Peroxisome proliferator-activated receptor alpha (PPARα) ligands have been reported to suppress cancer growth. However, the role of PPARα in hepatocarcinogenesis remains unclear. We investigated the functional significance of PPARα in hepatocellular carcinoma (HCC). PPARα-knockout (PPARα^-/-) mice were more susceptible to diethylnitrosamine (DEN)-induced HCC at 6 months compared with wild-type (WT) littermates (80% versus 43%, P < 0.05). In resected HCCs, TUNEL-positive apoptotic cells were significantly less in PPARα^-/- mice than in WT mice (P < 0.01), commensurate with a reduction in cleaved caspase-3 and caspase-7 protein expression. Ki-67 staining showed increased cell proliferation in PPARα^-/- mice (P < 0.01), with concomitant up-regulation of cyclin-D1 and down-regulation of p15. Moreover, ectopic expression of PPARα in HCC cells significantly suppressed cell proliferation and induced apoptosis. The anti-tumorigenic function of PPARα was mediated via NF-κB as evidenced by inhibition of NF-κB promoter activity, diminution of phosphor-p65, phosphor-p50 and BCL2 levels, and enhancing IkBa protein. Chromatin immunoprecipitation analysis confirmed PPARα directly binds to the IkBa promoter. In conclusion, PPARα deficiency enhances susceptibility to DEN-initiated HCC. PPARα suppresses tumor cell growth by inhibiting cell proliferation and inducing cell apoptosis via direct targeting IκBα and NF-κB signaling pathway.

Ning Zhang    Eagle sh Chu    Zhang Jingwan    Xiaoxing Li    Qiaoyi Liang    Jie Chen    陈旻湖    Teoh Narci C.    Geoffrey Farrell    沈祖堯     Jun Yu   

Oncotarget

2014

Background Gastric intestinal metaplasia (IM) is considered precancerous and is difficult to differentiate upon endoscopy. Endocytoscopy enables observation at a cellular level for focused biopsy. The present study examined the use of endocytoscopy for recognition of gastric IM. Patients and Methods Patients with a history of gastric IM were recruited. We first carried out narrow band imaging (NBI) endoscopy to look for suspicious areas of gastric IM. A prototype endocytoscope with a magnification of 450× was used to re-examine these areas. Areas examined were biopsied for histological comparison. Presence of goblet cells was considered as representative of IM upon endocytoscopy. Results Twenty patients were recruited with NBI demonstrating 102 suspicious lesions of gastric IM. Mean age of patients was 53.9 ± 7.6 years. Upon histology, 72 biopsies were confirmed as gastric IM, 15 showed IM and low-grade dysplasia, whereas 15were diagnosed as chronic gastritis. Endocytoscopy image quality was significantly better for areas of IM as compared to gastritis (P < 0.05; OR 21.7 [95% CI 4.5-105.9]). The presence of goblet cells upon endocytoscopy achieved a diagnostic accuracy of 0.86 for gastric IM. Receiver operator characteristics curve achieved an area under curve of 0.8 with the presence of goblet cells under endocytoscopy as compared to 0.64 for NBI alone. Conclusions Presence of goblet cells upon endocytoscopy indicates a diagnosis of gastric IM. Image quality of endocytoscopy, however, is suboptimal. Further developments in endocytoscopy should focus on image quality and staining methods to enhance differentiation between IM, dysplasia and early gastric cancer. © 2013 The Authors. Digestive Endoscopy © 2013 Japan Gastroenterological Endoscopy Society.

赵伟仁    Enders kwok wai Ng    To    Anthony Teoh    Candice Lam    Francis Chan    沈祖堯     James Lau   

Digestive Endoscopy

2014

A disintegrins and metalloproteinases with thrombospondinmotifs (ADAMTS) familymembers have been reported dysregulated in various cancers. Through refining a loss of heterozygosity locus at 11q25 by array-CGH, we identified ADAMTS8 as a novel candidate tumor suppressor gene. Although ADAMTS8 downregulation has been reported in several tumors, its biologic function and underlying mechanism remain largely unknown. Here, we found that ADAMTS8 is broadly expressed in normal tissues but frequently downregulated or silenced by promoter methylation in common carcinoma cell lines, including nasopharyngeal, esophageal squamous cell, gastric, and colorectal carcinomas. Pharmacologic or genetic demethylation restored ADAMTS8 expression, indicating that promoter methylation mediates its silencing. Aberrant methylation of ADAMTS8 was also detected in several types of primary tumors but rarely in normal tissues. Further functional studies showed that restoring ADAMTS8 expression suppressed tumor cell clonogenicity through inducing apoptosis.ADAMTS8as a secreted protease inhibited epidermal growth factor receptor (EGFR) signaling along with decreased levels of phosphorylated MEK and ERK. We further found that ADAMTS8 disrupted actin stress fiber organization and inhibited tumor cell motility. Thus, our data demonstrate that ADAMTS8 metalloprotease acts as a functional tumor suppressor through antagonizing EGFR-MEK-ERK signaling, in addition to its previously reported anti-angiogenesis function, and is frequently methylated in common tumors. Implications: This study uncovers the tumor suppressive function of ADAMTS8, one of the ADAMTS family members, and its frequent methylation in certain tumors could be developed as a potential biomarker. Mol Cancer Res; 12(2); 228-38. © 2013 AACR.

Choi Gigi Ching Gee    Li Jisheng    Wang Yajun    Li Li-Li    Zhong Lan    Brigette Ma    Xianwei Su    Jianming Ying    Tingxiu Xiang    Sunyoung Rha    Jun Yu    沈祖堯     George Tsao    Anthony Chan    Qian Tao   

Molecular Cancer Research

2014

The carboxyl terminus of Hsc70-interacting protein (CHIP, also named Stub1), a U-box containing E3 ubiquitin ligase, is involved in degradation of certain oncogenic proteins. Recent studies indicated that CHIP suppresses tumor progression in human cancers by targeting Src-3, hypoxia inducible factor 1a, NF-κB, ErbB2 and c-Myc. Here, we report that CHIP was downregulated, predominantly, in the late stages of human colorectal cancer (CRC), and that the CHIP promoter was hypermethylated in CRC specimens. Overexpression of CHIP in HCT-116 cells resulted in impaired tumor growth in nude mice and decreased abilities of tumor cell migration and invasion. Conversely, depletion of CHIP in HCT-116 cells promoted tumor growth and increased tumor cell migration and invasion. CHIP was further found to negatively regulate NF-κB signaling in HCT-116 cells by promoting ubiquitination and degradation of p65, a subunit of the NF-κB complex. The suppressive effect of CHIP led to decreased expression of NF-κB-targeted oncogenes including Cyclin D1, c-Myc, MMP-2, VEGF and IL-8. We proposed that CHIP inhibits the malignancy of CRC cells, possibly through targeting NF-κB signaling. This study provides functional evidence for CHIP as a potential tumor suppressor in CRC, and CHIP expression may be a marker for stages of CRC.

Wang Yangmeng    Ren Fangli    Wang Yin-Yin    Feng Yarui    Wang Dian-Jun    Jia Baoqing    Qiu Ying    Shiyan Wang    Jun Yu    沈祖堯     徐家科    Nikolajs Zeps    Zhijie Chang   

Carcinogenesis

2014

Helicobacter pylori and Epstein-Barr virus (EBV) account for roughly 80% and 10%, respectively, of gastric carcinomas worldwide. Autophagy is an evolutionarily conserved and intricately regulated cellular process that involves the sequestration of cytoplasmic proteins and organelles into double-membrane autophagosomes that eventually fuse with lysosomes for degradation of the engulfed content. Emerging evidence indicates that xenophagy, a form of selective autophagy, plays a crucial role in the pathogenesis of H. pylori- and EBV-induced gastric cancer. Xenophagy specifically recognizes intracellular H. pylori and EBV and physically targets these pathogens to the autophagosomal-lysosomal pathway for degradation. In this connection, H. pylori or EBV-induced dysregulation of autophagy may be causally linked to gastric tumourigenesis and therefore can be exploited as therapeutic targets. This review will discuss how H. pylori and EBV infection activate autophagy and how these pathogens evade recognition and degradation by the autophagic pathway. Elucidating the molecular aspects of H. pylori- and EBV-induced autophagy will help us better understand the pathogenesis of gastric cancer and promote the development of autophagy modulators as antimicrobial agents. Copyright © 2014 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Zhang Lin    沈祖堯     Yu Jun    Siew Ng    Sunny Wong    Chihin Cho    Simon siu man Ng    Francis Chan    William ka kei Wu   

Journal of Pathology

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.

Wu    Siew Ng    Yujuan Dong    Linwei Tian    吴兆文    Leung Wing-Wa    Law Wai Tak    Yau Tung On    Francis Chan    沈祖堯     Jun Yu   

Clinical Cancer Research

2014

Cathelicidin is a host defense peptide with multiple innate immunity-related functions. Recent findings indicate that cathelicidin is frequently dysregulated in human cancers where it plays a paradoxical yet dominant role in the regulation of tumor malignancy. In this review, the regulation of malignant phenotypes by cathelicidin in relation to the activation of its receptors and intracellular signaling is discussed. © 2014 Bentham Science Publishers.

William ka kei Wu    沈祖堯     Alfred Cheng    Francis Chan    Simon siu man Ng    Kafai To    Xiaojuan Wang    Zhang    Sunny Wong    Jun Yu    Chihin Cho   

Current Medicinal Chemistry

2014

Inflammatory cytokines modulate immune responses in the tumor microenvironment during progression. The role of interleukin (IL) 17A in cancer is currently under debate. We aim to investigate the expression of IL17A in situ tumors as well as in nontumor gastric mucosa tissues and further explore the functional significance of IL17A on gastric cancer cells in vitro. We found that compared with nontumor regions, the expression of IL17A were increased significantly in tumors of gastric cancer patients (P=0.007). The immunoreactivity for IL17A was found only in cytoplasm of inflammatory cells as well as vascular endothelial cells but not in tumor cells. Consistently, IL17A transcription was silenced in a variety of gastric cancer cell lines. In vitro, recombinant human IL17A protein promotes cell proliferation and monolayer wound healing of both AGS and SGC7901cells, in a dose-dependent manner. Besides, IL17A inhibits HO-induced cell apoptosis. Expression of IL6 and MMP13 mRNA was increased significantly after IL17A stimulation. These data suggest that accumulation of intratumoral IL17A-producing cells may promote gastric cancer progression directly or by inducing key signal transduction pathways implicated in gastric carcinogenesis. © 2014 International Society of Oncology and BioMarkers (ISOBM).

Wu Xiaoqin    曾志荣    Xu Lixia    Jun Yu    Cao Qing-Hua    陈旻湖    沈祖堯     Pinjin Hu   

Tumor Biology

2014

Background and Aims: Distinguishing Crohn's disease (CD) from intestinal tuberculosis (ITB) is a clinical challenge. This meta-analysis assessed the clinical usefulness of Interferon-gamma releasing assay (IGRA) and anti-Saccharomyces cerevisiae antibody (ASCA) in the diagnosis of ITB and CD, respectively. Methods: Systematic search without language restriction was conducted in AMED, EBM, MEDLINE, EMBASE, and Google Scholar until September 2013. Studies that have evaluated performance of IGRA (QuantiFERON-TB Gold or T-SPOT.TB) or ASCA in distinguishing ITB from CD were eligible. Main outcome measures included sensitivity and specificity. Random-effects models were used to combine estimates from studies with significant heterogeneity. Area under the curve (AUC) was used to measure accuracy of the tests. Results: Eleven studies (five IGRA, three ASCA, three IGRA and ASCA) involving 1081 subjects were included. The pooled sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio of IGRA for the diagnosis of ITB was 81% (95% CI, 75-86%), 85% (95% CI, 81-89%), 6.02 (95% CI: 4.62-7.83), and 0.19 (95% CI: 0.10-0.36), respectively. The AUC was 0.92. The pooled sensitivity and specificity of ASCA for the diagnosis of CD was 33% (95% confidence interval [CI], 27%-38%) and 83% (95% CI, 77-88%), respectively with an AUC of 0.58. T-SPOT.TB showed a higher sensitivity than QuantiFERON-TB Gold for the diagnosis of ITB. Conclusions: IGRA and ASCA have a high specificity for the diagnosis of ITB. Both IGRA and ASCA may have a supplementary role in the differential diagnosis between ITB and CD when conventional workup is not diagnostic. © 2014 Journal of Gastroenterology and Hepatology Foundation and Wiley Publishing Asia Pty Ltd.

Siew Ng    Hirai Hoyee W.    Kelvin kf Tsoi    Sunny Wong    Francis Chan    沈祖堯     Wu Justin C.Y.   

Journal of Gastroenterology and Hepatology (Australia)

2014

Background: Recent studies showed that previous negative results from faecal immunochemical tests (FITs) for colorectal cancer (CRC) screening was associated with lower risk of advanced neoplasia (AN). We evaluated whether prior FIT results should be included to estimate the risk of AN in 2008-2012.Methods: A community-based screening practice recruited 5,813 asymptomatic residents aged 50 to 70 years in Hong Kong for CRC screening. We included study participants who had (1). positive FIT with subsequent colonoscopy workup (FIT+ group; n5356); (2). negative FIT in three consecutive years and received a colonoscopy (FIT- group; n5857); (3). received colonoscopy without FIT (colonoscopy group; n5473); and (4). received both colonoscopy and FIT at the same time (combined group; n54,127). One binary logistic regression model evaluated whether prior FIT results were associated with colonoscopy findings of AN.Results: The proportion of participants having AN/CRC was 18.0% (FIT+), 5.5% (FIT-), 8.0% (colonoscopy group), and 4.3% (combined group), respectively. When compared with the colonoscopy group, those in the FIT- group were not significantly more or less likely to have AN/CRC (AOR 50.77, 95% C.I.50.51 to 1.18, p 50.230). Having one (AOR50.73, 95% C.I. 0.48-1.12, p50.151) or three consecutive negative FIT result (AOR50.98, 95% C.I. 0.60-1.62, p50.944) were not associated with lower risks of AN/CRC. Subjects in the FIT+ group was 3.32-fold (95% C.I. 2.07 to 5.32, p,0.001) more likely to have AN/CRC.Conclusions: These findings indicated that subjects with negative FIT findings could be risk stratified similarly as those who had not previously received FIT.

黄至生    Jessica Ching    Chan Victor C.W.    Shum Jeffrey P.    Lam Thomas Y.T.    Luk Arthur K.C.    沈祖堯     Keping Xie   

PLoS ONE

2014