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  • 1
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    German Medical Science GMS Publishing House; Düsseldorf
    In:  126. Kongress der Deutschen Gesellschaft für Chirurgie; 20090428-20090501; München; DOC09dgch11300 /20090423/
    Publication Date: 2009-05-06
    Keywords: ddc: 610
    Language: German
    Type: conferenceObject
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  • 2
    Abstract: In recent years, long non-coding RNA (lncRNA) research has identified essential roles of these transcripts in virtually all physiological cellular processes including tumorigenesis, but their functions and molecular mechanisms are poorly understood. In this study, we performed a high-throughput siRNA screen targeting 638 lncRNAs deregulated in cancer entities to analyse their impact on cell division by using time-lapse microscopy. We identified 26 lncRNAs affecting cell morphology and cell cycle including LINC00152. This transcript was ubiquitously expressed in many human cell lines and its RNA levels were significantly upregulated in lung, liver and breast cancer tissues. A comprehensive sequence analysis of LINC00152 revealed a highly similar paralog annotated as MIR4435-2HG and several splice variants of both transcripts. The shortest and most abundant isoform preferentially localized to the cytoplasm. Cells depleted of LINC00152 arrested in prometaphase of mitosis and showed reduced cell viability. In RNA affinity purification (RAP) studies, LINC00152 interacted with a network of proteins that were associated with M phase of the cell cycle. In summary, we provide new insights into the properties and biological function of LINC00152 suggesting that this transcript is crucial for cell cycle progression through mitosis and thus, could act as a non-coding oncogene.
    Type of Publication: Journal article published
    PubMed ID: 28536419
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  • 3
    Keywords: CELLS ; HEPATOCELLULAR-CARCINOMA ; MECHANISM ; COPY-NUMBER ; IMPORTIN-ALPHA ; HUMAN HOMOLOG ; SUSCEPTIBILITY GENE ; protein expression ; TARGET GENES ; SEGREGATION GENE CSE1
    Abstract: Proteins of the karyopherin superfamily including importins and exportins represent an essential part of the nucleocytoplasmic transport machinery. However, the functional relevance and regulation of karyopherins in hepatocellular carcinoma (HCC) is poorly understood. Here we identified cellular apoptosis susceptibility (CAS, exportin-2) and its transport substrate importin-alpha1 (imp-alpha1) among significantly up-regulated transport factor genes in HCC. Disruption of the CAS/imp-alpha1 transport cycle by RNAi in HCC cell lines resulted in decreased tumor cell growth and increased apoptosis. The apoptotic phenotype upon CAS depletion could be recapitulated by direct knockdown of the X-linked inhibitor of apoptosis (XIAP) and partially reverted by XIAP overexpression. In addition, XIAP and CAS mRNA expression levels were correlated in HCC patient samples (r=0.463; P〈0.01), supporting the in vivo relevance of our findings. Furthermore, quantitative mass spectrometry analyses of murine HCC samples (p53-/- versus p53+/+) indicated higher protein expression of CAS and imp-alpha1 in p53-/- tumors. Consistent with a role of p53 in regulating the CAS/imp-alpha1 transport cycle, we observed that both transport factors were repressed upon p53 induction in a p21-dependent manner. CONCLUSION: The CAS/imp-alpha1 transport cycle is linked to XIAP and is required to maintain tumor cell survival in HCC. Moreover, CAS and imp-alpha1 are targets of p53-mediated repression, which represents a novel aspect of p53's ability to control tumor cell growth in hepatocarcinogenesis.
    Type of Publication: Journal article published
    PubMed ID: 24799195
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  • 4
    Keywords: APOPTOSIS ; CANCER ; CELLS ; EXPRESSION ; GROWTH ; proliferation ; tumor ; carcinoma ; CELL ; Germany ; human ; IN-VIVO ; HEPATOCELLULAR-CARCINOMA ; DISTINCT ; GENE ; GENE-EXPRESSION ; GENES ; TUMORS ; ACTIVATION ; DNA ; INFECTION ; MECHANISM ; prognosis ; mechanisms ; BREAST-CANCER ; TARGET ; virus ; TRANSGENIC MICE ; COMPARATIVE GENOMIC HYBRIDIZATION ; gene expression ; NUMBER ; etiology ; RATES ; REGION ; ONCOGENE ; ALCOHOL ; OVEREXPRESSION ; gene expression profiling ; ALCOHOL-CONSUMPTION ; CONSUMPTION ; molecular ; RE ; ARRAY ; CANDIDATE GENES ; USA ; CANDIDATE ; CANCERS ; viral ; CHROMOSOME-ABERRATIONS ; ELONGATION-FACTOR EEF1A2
    Abstract: Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide and is characterized by aggressive tumor behavior coupled with poor prognosis. Various etiologies have been linked to HCC development, most prominently chronic hepatitis B and C virus infections as well as chronic alcohol consumption. In approximately 10% of HCCs, the etiology remains cryptic; however, recent epidemiological data suggest that most of these cryptogenic HCCs develop due to nonalcoholic steatohepatitis. To identify etiology-dependent DNA copy number aberrations and genes relevant to hepatocarcinogenesis, we performed array based comparative genomic hybridization of 63 HCCs of well-defined etiology and 4 HCC cell lines followed by gene expression profiling and functional analyses of candidate genes. For a 10-megabase chromosome region on 8q24, we observed etiology-dependent copy number gains and MYC overexpression in viral and alcohol-related HCCs, resulting in up-regulation of MYC target genes. Cryptogenic HCCs showed neither 8q24 gains, nor MYC overexpression, nor target gene activation, suggesting that tumors of this etiology develop by way of a distinct MYC-independent pathomechanism. Furthermore, we detected several etiology-independent small chromosome aberrations, including amplification of MDM4 on 1q32.1 and frequent gains of EEF1A2 on 20q13.33. Both genes were overexpressed in approximately half the HCCs examined, and gene silencing reduced cell viability as well as proliferation and increased apoptosis rates in HCC cell fines. Conclusion: Our findings suggest that MDM4 and EEF1A2 act as etiology-independent oncogenes in a significant percentage of HCCs
    Type of Publication: Journal article published
    PubMed ID: 18161050
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  • 5
    Abstract: In biomedical research, a variety of data like clinical, genetic, expression of coding or non-coding ribonucleic acid (RNA) transcripts, or proteomic data are processed to gain new insights into diseases and therapies. In transregional research networks, geographically distributed projects work on comparable research questions with data from different resources and in different formats. Providing an information platform that integrates the data of the projects can enable cross-project analysis and provides an overview of available data and resources (tissue, blood, etc.). For a German liver cancer research network consisting of 22 individual projects, we develop the integrated information platform pelican - platform enhancing liver cancer networked research. In our generic approach, data are made available to the research network by standardized data services based on technologies provided by the cancer Biomedical Informatics Grid (caBIG). It has shown that publishing service metadata in a corresponding repository is a major prerequisite for automated discovery, integration, and conversion of data records and data services. We identified data confidentiality and intellectual property considerations as major challenges while establishing such an integrated information platform. As a first result we implemented a working prototype to validate our approach.
    Type of Publication: Journal article published
    PubMed ID: 21893870
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  • 6
    Keywords: COMPLEX ; INFECTION ; IDENTIFICATION ; CORE PROTEIN ; SCREEN ; host factors ; CELLULAR COFACTORS ; HUH-7 CELLS ; PHOSPHATIDYLINOSITOL 4-KINASES ; RNA REPLICATION
    Abstract: Hepatitis C virus (HCV) is a major causative agent of chronic liver disease in humans. To gain insight into host factor requirements for HCV replication, we performed a siRNA screen of the human kinome and identified 13 different kinases, including phosphatidylinositol-4 kinase III alpha (PI4KIIIalpha), as being required for HCV replication. Consistent with elevated levels of the PI4KIIIalpha product phosphatidylinositol-4-phosphate (PI4P) detected in HCV-infected cultured hepatocytes and liver tissue from chronic hepatitis C patients, the enzymatic activity of PI4KIIIalpha was critical for HCV replication. Viral nonstructural protein 5A (NS5A) was found to interact with PI4KIIIalpha and stimulate its kinase activity. The absence of PI4KIIIalpha activity induced a dramatic change in the ultrastructural morphology of the membranous HCV replication complex. Our analysis suggests that the direct activation of a lipid kinase by HCV NS5A contributes critically to the integrity of the membranous viral replication complex.
    Type of Publication: Journal article published
    PubMed ID: 21238945
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  • 7
    Keywords: EXPRESSION ; COMPLEX ; CANCER-CELLS ; STEM-CELLS ; LIVER-CANCER ; HUMAN HEPATOCELLULAR-CARCINOMA ; DNA METHYLATION PATTERNS ; HUMAN HEPATOCARCINOGENESIS ; CIRCADIAN GENE ; DISTINCT PATHWAYS
    Abstract: To identify new tumor-suppressor gene candidates relevant for human hepatocarcinogenesis, we performed genome-wide methylation profiling and vertical integration with array-based comparative genomic hybridization (aCGH), as well as expression data from a cohort of well-characterized human hepatocellular carcinomas (HCCs). Bisulfite-converted DNAs from 63 HCCs and 10 healthy control livers were analyzed for the methylation status of more than 14,000 genes. After defining the differentially methylated genes in HCCs, we integrated their DNA copy-number alterations as determined by aCGH data and correlated them with gene expression to identify genes potentially silenced by promoter hypermethylation. Aberrant methylation of candidates was further confirmed by pyrosequencing, and methylation dependency of silencing was determined by 5-aza-2'-deoxycytidine (5-aza-dC) treatment. Methylation profiling revealed 2,226 CpG sites that showed methylation differences between healthy control livers and HCCs. Of these, 537 CpG sites were hypermethylated in the tumor DNA, whereas 1,689 sites showed promoter hypomethylation. The hypermethylated set was enriched for genes known to be inactivated by the polycomb repressive complex 2, whereas the group of hypomethylated genes was enriched for imprinted genes. We identified three genes matching all of our selection criteria for a tumor-suppressor gene (period homolog 3 [PER3], insulin-like growth-factor-binding protein, acid labile subunit [IGFALS], and protein Z). PER3 was down-regulated in human HCCs, compared to peritumorous and healthy liver tissues. 5-aza-dC treatment restored PER3 expression in HCC cell lines, indicating that promoter hypermethylation was indeed responsible for gene silencing. Additionally, functional analysis supported a tumor-suppressive function for PER3 and IGFALS in vitro. Conclusion: The present study illustrates that vertical integration of methylation data with high-resolution genomic and transcriptomic data facilitates the identification of new tumor-suppressor gene candidates in human HCC. (HEPATOLOGY 2012;56:1817-1827).
    Type of Publication: Journal article published
    PubMed ID: 22689435
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  • 8
    Keywords: HEPATOCELLULAR-CARCINOMA ; NF-KAPPA-B ; STEM-CELLS ; PROGENITOR CELLS ; REPERFUSION INJURY ; END-PRODUCTS RAGE ; ETHIONINE-SUPPLEMENTED DIET ; GROUP BOX 1 ; ISCHEMIA-REPERFUSION ; CHOLINE-DEFICIENT
    Abstract: The receptor for advanced glycation endproducts (RAGE) is a multiligand receptor and member of the immunoglobulin superfamily. RAGE is mainly involved in tissue damage and chronic inflammatory disorders, sustaining the inflammatory response upon engagement with damage-associated molecular pattern molecules (DAMPs) such as S100 proteins and high-mobility group box 1 (HMGB1). Enhanced expression of RAGE and its ligands has been demonstrated in distinct tumors and several studies support its crucial role in tumor progression and metastasis by still unknown mechanisms. Here we show that RAGE supports hepatocellular carcinoma (HCC) formation in the Mdr2(-/-) mouse model, a prototype model of inflammation-driven HCC formation, which mimics the human pathology. Mdr2(-/-) Rage(-/-) (dKO) mice developed smaller and fewer HCCs than Mdr2(-/-) mice. Interestingly, although in preneoplastic Mdr2(-/-) livers RAGE ablation did not affect the onset of inflammation, premalignant dKO livers showed reduced liver damage and fibrosis, in association with decreased oval cell activation. Oval cells expressed high RAGE levels and displayed reduced proliferation upon RAGE silencing. Moreover, stimulation of oval cells with HMGB1 promoted an ERK1/2-Cyclin D1-dependent oval cell proliferation in vitro. Finally, genetic and pharmacologic blockade of RAGE signaling impaired oval cell activation in an independent mouse model of oval cell activation, the choline deficient ethionine-supplemented dietary regime. Conclusion: Our data identified a novel function of RAGE in regulating oval cell activation and tumor development in inflammation-associated liver carcinogenesis.
    Type of Publication: Journal article published
    PubMed ID: 23504974
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  • 9
    Keywords: CANCER ; EXPRESSION ; SURVIVAL ; HEPATOCELLULAR-CARCINOMA ; GENES ; GROWTH-FACTOR RECEPTOR ; TUMOR PROGRESSION ; snail ; hepatitis
    Abstract: The cell adhesion molecule E-cadherin has critical functions in development and carcinogenesis. Impaired expression of E-cadherin has been associated with disrupted tissue homeostasis, progression of cancer and a worse patient prognosis. So far, the role of E-cadherin in homeostasis and carcinogenesis of the liver is not well understood. By use of a mouse model with liver-specific deletion of E-cadherin and administration of the carcinogen diethylnitrosamin, we demonstrate that loss of E-cadherin expression in hepatocytes results in acceleration of the growth of hepatocellular carcinoma (HCC). In contrast, liver regeneration is not disturbed in mice lacking E-cadherin expression in hepatocytes. In human HCC we observed four different expression patterns of E-cadherin. Notably, atypical cytosolic expression of E-cadherin was positively correlated with a poorer patient prognosis: The median overall survival of patients with HCC expressing E-cadherin on the membrane only was 221 weeks (95% confidence interval (CI), 51-391) compared to 131 weeks in patients with cytosolic expression (95% CI, 71 - 191 weeks; p〈0.05). In conclusion, we demonstrate that impaired expression of E-cadherin promotes hepatocellular carcinogenesis and is associated with a worse prognosis in humans.
    Type of Publication: Journal article published
    PubMed ID: 24840851
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  • 10
    Keywords: CANCER ; CELLS ; GROWTH ; MICE ; ACTIVATION ; SIGNALING PATHWAYS ; TUMOR-SUPPRESSOR ; senescence ; ACTIN ; SOMATIC MUTATIONS
    Abstract: The ubiquitously expressed transcriptional regulator serum response factor (SRF) is controlled by both Ras/MAPK (mitogen-activated protein kinase) and Rho/actin signaling pathways, which are frequently activated in hepatocellular carcinoma (HCC). We generated SRF-VP16(iHep) mice, which conditionally express constitutively active SRF-VP16 in hepatocytes, thereby controlling subsets of both Ras/MAPK- and Rho/actin-stimulated target genes. All SRF-VP16(iHep) mice develop hyperproliferative liver nodules that progresses to lethal HCC. Some murine (m)HCCs acquire Ctnnb1 mutations equivalent to those in human (h)HCC. The resulting transcript signatures mirror those of a distinct subgroup of hHCCs, with shared activation of oncofetal genes including Igf2, correlating with CpG hypomethylation at the imprinted Igf2/H19 locus. Conclusion: SRF-VP16(iHep) mHCC reveal convergent Ras/MAPK and Rho/actin signaling as a highly oncogenic driver mechanism for hepatocarcinogenesis. This suggests simultaneous inhibition of Ras/MAPK and Rho/actin signaling as a treatment strategy in hHCC therapy.
    Type of Publication: Journal article published
    PubMed ID: 25266280
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