The mutagenic effect of hepatitis B (HBV) integration in predisposing risk to hepatocellular carcinoma (HCC) remains elusive. In this study, we performed transcriptome sequencing of HBV-positive HCC cell lines and showed transcription of viral-human gene fusions from the site of genome integrations. We discovered tumor-promoting properties of a chimeric HBx-LINE1 that, intriguingly, functions as a hybrid RNA. HBx-LINE1 can be detected in 23.3% of HBV-associated HCC tumors and correlates with poorer patient survival. HBx-LINE1 transgenic mice showed heightened susceptibility to diethylnitrosamine-induced tumor formation. We further show that HBx-LINE1 expression affects β-catenin transactivity, which underlines a role in activating Wnt signaling. Thus, this study identifies a viral-human chimeric fusion transcript that functions like a long noncoding RNA to promote HCC.

Allelic loss of chromosome region 3p21 is one of the most frequent events in the development of human cancers including lung, breast and bladder cancer. 1-3 A gene called RASSF1 has been discovered recently in this chromosome region. 4 One of the splice variants of this gene, RASSF1A, is inactivated frequently in many cancers including lung, breast and bladder by promoter hypermethylation. 5,6 Therefore both genetic and epigenetic alterations appeared to be involved in the RASSF1A inactivation. Furthermore, re-expression experiment in lung and renal cell carcinoma found that RASSF1A suppressed tumor growth in soft agar assay and in nude mice model. 5,7 These studies suggest that RASSF1A function as a tumor suppressor gene. Based on the presence of the RAS association domain in protein of RASSF1A, it is suggested that it exerts its function through RAS-mediated pathway. 4 More recently, RASSF1A is found to exert its effect by binding with novel RAS effector, Nore1 and MTS1. 8,9 Bladder cancer is the 6th most common cancer in the world. 10 Transitional cell carcinoma comprising the majority of bladder cancer, displays the multiple metachronous or synchronous features. Bladder cancer patients need a long-term follow-up with repeated urine cytology and cystoscopy for monitoring. 11 Conventional urine cytology has been the standard method for cancer detection. The sensitivity is low, however, especially for low grade transitional cell carcinoma (TCC). Therefore, a more sensitive and non-invasive method is required for cancer detection. We have reported previously that promoter hypermethylation of four cancer-related genes can be detected in voided urine of bladder cancer patients and appears to be more sensitive than conventional cytology in cancer detection. 12 In our study, we investigate the frequency of LOH in 3p21 regions and methylation status of RASSF1A in bladder cancer tissues. We also investigate the feasibility of detecting methylation of RASSF1A in voided urine and its potential role as tumor marker for bladder cancer. MATERIAL AND METHODS Tissues samplesForty bladder tumor tissues samples from transurethral resection specimens (8 frozen samples and 32 paraffin-embedded samples) were obtained at the Prince of Wales Hospital. Paraffin-embedded tissues from 6 samples of carcinoma in situ and 6 samples of normal urothelium from individuals without bladder cancer were also included. The clinical pathological data for all the tissue samples are summarized in Table I. Three human bladder cancer cell lines (T24, UMUC3 and J82) were obtained from American Type Culture Collection (Rockville, MD). Urine samplesPaired voided urine samples were collected from 14 patients ( Table I). The urine samples were spun down and the urine sediments were subjected to subsequent analysis. The corresponding urine samples were also subjected to conventional urine cytology examination by an experienced pathologist without knowledge of the methylation results. In Addition, 10 normal voided urine sediments from age-and gender-match c...

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 ¼ 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.

No abstract

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/b-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 b-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 b-catenin signaling. Conversely, ectopic overexpression of EZH2 in immortalized hepatocytes activated Wnt/b-catenin signaling to promote cellular proliferation. In human HCCs, concomitant overexpression of EZH2 and b-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/b-catenin signaling and consequential proliferation of HCC cells, thus representing a novel therapeutic target for this highly malignant tumor. Cancer Res; 71(11); 4028-39. Ó2011 AACR.

Severe acute respiratory syndrome (SARS) is a new human infectious disease with significant morbidity and mortality. The disease has been shown to be associated with a new coronavirus (SARS-CoV). The clinical and epidemiological aspects of SARS have been described. Moreover, the viral genome of SARS-CoV has been fully sequenced. However, much of the biological behaviour of the virus is not known and data on the tissue and cellular tropism of SARS-CoV are limited. In this study, six fatal cases of SARS were investigated for the tissue and cellular tropism of SARS-CoV using an in-situ hybridization (ISH) technique. Among all the tissues studied, positive signals were seen in pneumocytes in the lungs and surface enterocytes in the small bowel. Infected pneumocytes were further confirmed by immunofluorescence-fluorescence in-situ hybridization (FISH) analysis. These results provide important information concerning the tissue tropism of SARS-CoV, which is distinct from previously identified human coronaviruses, and suggest the possible involvement of novel receptors in this infection. Whereas the lung pathology was dominated by diffuse alveolar damage, the gut was relatively intact. These findings indicated that tissue responses to SARS-CoV infection are distinct in different organs.

Our results delineate an immunosuppressive mechanism of the hepatoma-intrinsic CCRK signalling and highlight an overexpressed kinase target whose inhibition might empower HCC immunotherapy.

Cathelicidins are a family of bacteriocidal polypeptides secreted by macrophages and polymorphonuclear leukocytes (PMN). LL-37, the only human cathelicidin, has been implicated in tumorigenesis, but there has been limited investigation of its expression and function in cancer. Here, we report that LL-37 activates a p53-mediated, caspase-independent apoptotic cascade that contributes to suppression of colon cancer. LL-37 was expressed strongly in normal colon mucosa but downregulated in colon cancer tissues, where in both settings its expression correlated with terminal deoxynucleotidyl transferase–mediated dUTP nick end labeling-positive apoptotic cells. Exposure of colon cancer cells to LL-37 induced phosphatidylserine externalization and DNA fragmentation in a manner independent of caspase activation. Apoptogenic function was mediated by nuclear translocation of the proapoptotic factors, apoptosis-inducing factor (AIF) and endonuclease G (EndoG), through p53-dependent upregulation of Bax and Bak and downregulation of Bcl-2 via a pertussis toxin–sensitive G-protein–coupled receptor (GPCR) pathway. Correspondingly, colonic mucosa of cathelicidin-deficient mice exhibited reduced expression of p53, Bax, and Bak and increased expression of Bcl-2 together with a lower basal level of apoptosis. Cathelicidin-deficient mice exhibited an increased susceptibility to azoxymethane-induced colon tumorigenesis, establishing pathophysiologic relevance in colon cancer. Collectively, our findings show that LL-37 activates a GPCR-p53-Bax/Bak/Bcl-2 signaling cascade that triggers AIF/EndoG–mediated apoptosis in colon cancer cells.