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  • Germany  (12)
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  • 1
    Keywords: CELLS ; EXPRESSION ; Germany ; SYSTEMS ; GENE ; GENE-EXPRESSION ; GENES ; microarray ; SACCHAROMYCES-CEREVISIAE ; METABOLISM ; COMPLEX ; COMPLEXES ; SEQUENCE ; METABOLITES ; gene expression ; ESCHERICHIA-COLI ; DATABASE ; OXYGEN ; CLUSTER ; MATRIX ; SYNTHETASE ; EXTRACTION ; LEVEL ; ENZYME ; TECHNOLOGY ; EXPRESSION PATTERNS ; CHAIN AMINO-ACIDS ; K-12
    Abstract: Background: Microarray technology produces gene expression data on a genomic scale for an endless variety of organisms and conditions. However, this vast amount of information needs to be extracted in a reasonable way and funneled into manageable and functionally meaningful patterns. Genes may be reasonably combined using knowledge about their interaction behaviour. On a proteomic level, biochemical research has elucidated an increasingly complete image of the metabolic architecture, especially for less complex organisms like the well studied bacterium Escherichia coli. Results: We sought to discover central components of the metabolic network, regulated by the expression of associated genes under changing conditions. We mapped gene expression data from E. coli under aerobic and anaerobic conditions onto the enzymatic reaction nodes of its metabolic network. An adjacency matrix of the metabolites was created from this graph. A consecutive ones clustering method was used to obtain network clusters in the matrix. The wavelet method was applied on the adjacency matrices of these clusters to collect features for the classifier. With a feature extraction method the most discriminating features were selected. We yielded network sub-graphs from these top ranking features representing formate fermentation, in good agreement with the anaerobic response of heterofermentative bacteria. Furthermore, we found a switch in the starting point for NAD biosynthesis, and an adaptation of the l-aspartate metabolism, in accordance with its higher abundance under anaerobic conditions. Conclusion: We developed and tested a novel method, based on a combination of rationally chosen machine learning methods, to analyse gene expression data on the basis of interaction data, using a metabolic network of enzymes. As a case study, we applied our method to E. coli under oxygen deprived conditions and extracted physiologically relevant patterns that represent an adaptation of the cells to changing environmental conditions. In general, our concept may be transferred to network analyses on biological interaction data, when data for two comparable states of the associated nodes are made available
    Type of Publication: Journal article published
    PubMed ID: 16524469
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  • 2
    Keywords: tumor ; Germany ; COHORT ; GENE ; HYBRIDIZATION ; TUMORS ; PATIENT ; MARKER ; SEQUENCE ; DELETION ; STAGE ; AMPLIFICATION ; COMPARATIVE GENOMIC HYBRIDIZATION ; COPY NUMBER ; PATTERNS ; microarrays ; NUMBER ; MARKERS ; REGION ; REGIONS ; PHENOTYPE ; REVEALS ; CHILDREN ; SEGMENTS ; 1p ; neuroblastoma ; CHROMOSOMES ; SUBSET ; CYTOGENETIC ANALYSIS ; BREAKPOINTS ; MYCN-AMPLIFICATION ; function ; LOSSES ; HIGH-RESOLUTION ANALYSIS ; genomic ; GENOMIC ALTERATIONS ; 11Q ; CGH ANALYSIS ; DNA-COPY-NUMBER
    Abstract: The study of genomic alterations in neuroblastoma is of particular importance since several cytogenetic markers proved to be closely associated with the clinical phenotype. To disclose patterns of gains and losses, we performed high-resolution oligonucleotide array-based comparative genomic hybridization (aCGH). A total cohort of 90 patients was classified into 6 subsets according to tumor stage and outcome: Stages 1-3+ (with event), Stage 1-3- (no event), Stage 4+/-, and Stage 4S+/-. The aberration patterns in Stages 1-3- and 4S- tumors differed from all other groups as they were predominantly characterized by losses (3, 4, 14, X) and gains (7, 17) of whole chromosomes. However, 59/65 (91%) tumors of Stages 1-3+ or Stage 4 revealed numerous structural copy number alterations (sCNA). While deletions in chromosomes 1, 3, and I I discriminated outcome in Stage 4, there were no specific sCNA that distinguished tumor stage within the subgroup of unfavorable tumors. sCNA in 1p, 3p, 11q, 17q, or MYCN amplification (MNA) was seen among 22/24 patients who died, 10/12 with metastatic relapses, and 5/9 with local recurrences. Detailed breakpoint analyses on chromosomes 1, 3, 11, and 17 disclosed preferred breaking areas, although breakpoints were not identical. Amplifications were found in 18 patients and involved 2p24 (MYCN) and other segments of chromosome 2, as well as regions on chromosome arms 6q, 12q, and 17q. One single feature in 21q21.1 (BU678720, without known function yet) attracted particular attention since five patients showed a homozygous loss of this sequence. This article contains Supplementary Material available at http://www.interscience.wiley.com/jpages/1045-2257/suppmat. (c) 2006 Wiley-Liss, Inc
    Type of Publication: Journal article published
    PubMed ID: 16958102
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  • 3
    Keywords: ENVIRONMENT ; SPECTRA ; CELLS ; EXPRESSION ; GROWTH ; CELL ; Germany ; PATHWAY ; PATHWAYS ; INFORMATION ; SYSTEM ; SYSTEMS ; GENE ; GENE-EXPRESSION ; GENOME ; microarray ; SACCHAROMYCES-CEREVISIAE ; METABOLISM ; DOWN-REGULATION ; treatment ; culture ; PATTERNS ; gene expression ; MICROARRAY DATA ; ESCHERICHIA-COLI ; UP-REGULATION ; OXYGEN ; CLUSTERS ; TRANSCRIPTIONAL REGULATION ; CLUSTER ; RE ; PRODUCTS ; HYDROGEN-PEROXIDE ; EXCRETION ; LEVEL ; methods ; PROFILES ; EXPRESSION PROFILES ; technique ; uptake ; E ; SPECTRUM ; microbiology ; image processing ; TOPOLOGY ; METABOLIC PATHWAYS ; SALMONELLA-TYPHIMURIUM ; ADAPTIVE RESPONSE ; ANAEROBIC RESPIRATION ; DEOXYRIBONUCLEOTIDE SYNTHESIS ; FUMARATE REDUCTASE ; MULTIORGANISM DATABASE
    Abstract: Background: Biochemical investigations over the last decades have elucidated an increasingly complete image of the cellular metabolism. To derive a systems view for the regulation of the metabolism when cells adapt to environmental changes, whole genome gene expression profiles can be analysed. Moreover, utilising a network topology based on gene relationships may facilitate interpreting this vast amount of information, and extracting significant patterns within the networks. Results: Interpreting expression levels as pixels with grey value intensities and network topology as relationships between pixels, allows for an image-like representation of cellular metabolism. While the topology of a regular image is a lattice grid, biological networks demonstrate scale-free architecture and thus advanced image processing methods such as wavelet transforms cannot directly be applied. In the study reported here, one-dimensional enzyme-enzyme pairs were tracked to reveal sub-graphs of a biological interaction network which showed significant adaptations to a changing environment. As a case study, the response of the hetero-fermentative bacterium E. coli to oxygen deprivation was investigated. With our novel method, we detected, as expected, an up-regulation in the pathways of hexose nutrients up-take and metabolism and formate fermentation. Furthermore, our approach revealed a down-regulation in iron processing as well as the up-regulation of the histidine biosynthesis pathway. The latter may reflect an adaptive response of E. coli against an increasingly acidic environment due to the excretion of acidic products during anaerobic growth in a batch culture. Conclusion: Based on microarray expression profiling data of prokaryotic cells exposed to fundamental treatment changes, our novel technique proved to extract system changes for a rather broad spectrum of the biochemical network
    Type of Publication: Journal article published
    PubMed ID: 17488495
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  • 4
    Keywords: CANCER ; CELLS ; EXPRESSION ; GROWTH ; GROWTH-FACTOR ; carcinoma ; Germany ; INHIBITION ; GENE ; PROTEIN ; PROTEINS ; LINES ; INFECTION ; MECHANISM ; prognosis ; CARCINOGENESIS ; mechanisms ; CELL-LINES ; E7 ; DELETION ; LESIONS ; PROGRESSION ; CARCINOMA CELLS ; WOMEN ; COLORECTAL-CANCER ; CERVICAL-CANCER ; LINE ; TUMOR-SUPPRESSOR GENE ; human papillomavirus ; CARCINOMA-CELLS ; BETA ; CERVICAL-CARCINOMA ; CARCINOMAS ; squamous cell carcinoma ; intraepithelial neoplasia ; UTERINE CERVIX ; GROWTH-FACTOR-BETA ; POOR-PROGNOSIS ; cell lines ; GENOMIC INSTABILITY ; FACTOR-BETA ; molecular ; DEFICIENCY ; TUMOR-SUPPRESSOR ; TUMOR-GROWTH ; TGF-BETA ; MOLECULAR-MECHANISMS ; RESPONSIVENESS ; carcinoma cell ; CIN lesion ; cytogenetic ; DPC4 INACTIVATION ; multistep carcinogenesis ; PAPILLOMAVIRUS INFECTIONS ; SUPPRESSOR ; TGF beta ; tumor suppressor gene
    Abstract: Squamous cell carcinoma of the uterine cervix is one of the most frequent cancers affecting women worldwide. Carcinomas arise from cervical intraepithelial lesions, in which infection with high-risk human papillomavirus types has led to deregulated growth control through the actions of the viral E6 and E7 oncoproteins. The molecular mechanisms underlying progression to invasive tumor growth are poorly understood. One important feature, however, is the escape from growth inhibition by transforming growth factor beta (TGF-beta). Loss of chromosomal arm 18q is among the most frequent cytogenetic alterations in cervical cancers and has been associated with poor prognosis. Since the TGF-beta response is mediated by Smad proteins and the tumor suppressor gene Smad4 resides at 18q21, we have analysed the Smad4 gene for cervical cancer-associated alterations in cell lines and primary carcinomas. Here, we report Smad4 deficiency in four out of 13 cervical cancer cell lines which is due to an intronic rearrangement or deletions of 30 exons. All cell lines, however, showed either absent or moderate responsiveness to TGF-beta irrespective of their Smad4 status. In 41 primary squamous cervical carcinomas analysed, 10 samples showed loss of Smad4 protein expression and 26 samples a reduced expression. Altogether, our results strongly suggest that Smad4 gene alterations are involved in cervical carcinogenesis
    Type of Publication: Journal article published
    PubMed ID: 15531914
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  • 5
    Keywords: CANCER ; EXPRESSION ; IN-VITRO ; SURVIVAL ; tumor ; CELL ; Germany ; IN-VIVO ; VITRO ; VIVO ; GENE ; transcription ; cell line ; TISSUE ; TUMORS ; LINES ; PATIENT ; ACTIVATION ; TRANSCRIPTION FACTOR ; MARKER ; REDUCTION ; TISSUES ; CELL-LINES ; NO ; AMPLIFICATION ; COPY NUMBER ; ASSAY ; NUMBER ; RATES ; CELL-LINE ; chemotherapy ; LINE ; MELANOMA ; METASTATIC MELANOMA ; PCR ; ONCOGENE ; MALIGNANT-MELANOMA ; MELANOMA PATIENTS ; real-time PCR ; cell lines ; ONCOLOGY ; RE ; PATIENT SURVIVAL ; chemosensitivity ; LINEAGE ; REAL-TIME ; TUMOR TISSUE ; biomarker ; analysis ; methods ; USA ; correlation ; cancer research ; in vivo ; LINEAGE SURVIVAL ; MITF ; quantitative ; MELANOMAS ; LUMINESCENCE ; chemotherapeutics ; MASTER REGULATOR
    Abstract: Purpose: The microphthalmia-associated transcription factor (MITF) is regarded as a key oncogene of the melanocytic lineage since it was detected by a genome-wide analysis to be strongly amplified in 15% to 20% of metastatic melanomas. MITF gene amplification was shown to be associated with a reduced survival in metastatic melanoma patients, and reduction of MITF activity was shown to sensitize melanoma cell lines to chemotherapeutics, suggesting the intratumoral MITF gene copy number as a predictive biomarker of response and survival after chemotherapy. Patients and Methods: To validate this hypothesis, we investigated MITF gene amplification in tumor tissues obtained from 116 metastatic melanoma patients before an individualized sensitivity-directed chemotherapy using quantitative real-time PCR. MITF amplification rates were correlated with tumor chemosensitivity quantified by an ATP-based luminescence assay and with chemotherapy outcome in terms of response and survival. Results: Of 116 tumor tissues, 104 were evaluable for MITF gene amplification. Strong amplification (〉= 4 copies per cell) was detected in 24 of 104 tissues (23%), whereas 62 of 104 tissues (60%) harbored 〉3 copies per cell. Strong MITF gene amplification was associated with a reduced disease-specific survival (P = 0.031). However, no correlation was found between MITF copy number and in vitro chemosensitivity or in vivo chemotherapy response. Conclusion: Our findings suggest that strong amplifications of the melanoma oncogene MITF affects patient survival but does not influence tumor chemosensitivity and chemotherapy response. Thus, the MITF gene copy number seems a useful prognostic marker in metastatic melanoma but could not be confirmed as a predictive marker of chemosensitivity and chemotherapy response
    Type of Publication: Journal article published
    PubMed ID: 17975146
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  • 6
    Keywords: RECEPTOR ; CANCER ; CELLS ; SURVIVAL ; tumor ; carcinoma ; Germany ; CLASSIFICATION ; DIAGNOSIS ; FOLLOW-UP ; COHORT ; DISEASE ; HISTORY ; LONG-TERM ; NEW-YORK ; POPULATION ; GENE ; PROTEIN ; SAMPLE ; SAMPLES ; PATIENT ; RANTES ; DNA ; IMPACT ; primary ; polymorphism ; NO ; PROGRESSION ; MELANOMA ; METASTATIC MELANOMA ; PCR ; MULTIVARIATE ; IMMUNE-RESPONSE ; IMMUNOTHERAPY ; vaccination ; chemokine ; SERUM ; ONCOLOGY ; TUMOR-GROWTH ; PATIENT SURVIVAL ; CCR5 ; analysis ; methods ; USA ; immunology
    Abstract: Purpose Chemokines influence both tumor progression and anti-tumor immune response. A 32-bp-deletion polymorphism in the chemokine receptor 5 gene (CCR5 Delta 32) has been shown to result in a non-functional protein. This study was aimed at evaluating the potential impact of this gene polymorphism on disease progression and treatment outcome in patients with melanoma. patients and methods CCR5 genotyping was performed by PCR on DNA extracted from serum samples of 782 cutaneous melanoma patients with known disease history and long-term clinical follow-up. Genotypes were correlated with patient survival and types of treatment. Results Of 782 melanoma patients, 90 (11.5%) were heterozygous and 12 (1.5%) were homozygous for CCR5 Delta 32. Analyzing the complete cohort, the disease-specific survival from date of primary diagnosis was not influenced by CCR5 status. Similarly, no significant impact could be detected on the treatment outcome of stage III patients. In 139 stage IV patients receiving immunotherapy, CCR5 Delta 32 was associated with a decreased survival compared to patients not carrying the deletion (median 12.5 vs. 20.3 months, P = 0.029). Multivariate analysis revealed the CCR5 genotype as an independent factor impacting disease-specific survival in this patient population (P = 0.002), followed by gender (P = 0.019) and pathological classification of the primary (pT; P = 0.022). Conclusion The presence of the CCR5 Delta 32 polymorphism in patients with stage IV melanoma results in a decreased survival following immunotherapy and may help to select patients less likely to benefit from this type of treatment
    Type of Publication: Journal article published
    PubMed ID: 17909797
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  • 7
    Keywords: CANCER ; CANCER CELLS ; CELLS ; EXPRESSION ; GROWTH ; INVASION ; tumor ; TUMOR-CELLS ; CELL ; Germany ; human ; SITE ; SITES ; GENE ; GENES ; transcription ; COMPONENTS ; MOLECULES ; TISSUE ; MECHANISM ; FAMILY ; TRANSCRIPTION FACTOR ; IMPACT ; CARCINOGENESIS ; INDUCTION ; mechanisms ; BINDING ; SIGNAL ; MOLECULE ; ALPHA ; cytokines ; TARGET ; DELETION ; CHROMATIN ; PROMOTER ; MEMBRANE ; PROMOTERS ; MUTATION ; inactivation ; DERIVATIVES ; REGION ; CANCER-CELLS ; REGIONS ; MUTATIONS ; BETA ; SUPERFAMILY ; GROWTH-FACTOR-BETA ; TRANSCRIPTIONAL REGULATION ; GAMMA-2 CHAIN ; CYTOKINE ; molecular ; ONCOLOGY ; FAMILIES ; TUMOR SUPPRESSION ; TUMOR-SUPPRESSOR ; basement membrane ; TRANSFECTION ; TGF-BETA ; interaction ; MOLECULAR-MECHANISMS ; methods ; SUPPRESSOR ; TGF beta ; SIGNALS ; COLON-CARCINOMA CELLS ; BARRIER ; ENGLAND ; UPSTREAM ; response ; synthesis ; Smad4 ; SUPPRESSOR E-CADHERIN ; chromatin immunoprecipitation ; tumor suppressor ; FUNCTIONAL INACTIVATION ; BINDING SITE ; ACTIVATOR PROTEIN-1 ; AP-1 COMPLEX
    Abstract: Background: Functional inactivation of the tumor suppressor Smad4 in colorectal and pancreatic carcinogenesis occurs coincident with the transition to invasive growth. Breaking the basement membrane ( BM) barrier, a prerequisite for invasive growth, can be due to tumor induced proteolytic tissue remodeling or to reduced synthesis of BM molecules by incipient tumor cells. Laminin-332 (laminin-5), a heterotrimeric BM component composed of alpha 3-, beta 3- and gamma 2-chains, has recently been identified as a target structure of Smad4 and represents the first example for expression control of an essential BM component by a tumor and invasion suppressor. Biochemically Smad4 is a transmitter of signals of the TGF beta superfamily of cytokines. We have reported previously, that Smad4 functions as a positive transcriptional regulator of constitutive and of TGF beta-induced transcription of all three genes encoding Laminin-332, LAMA3, LAMB3 and LAMC2. Methods: Promoter-reporter constructs harboring 4 kb upstream regions, each of the three genes encoding Laminin-322 as well as deletion and mutations constructs were established. Promoter activities and TGF beta induction were assayed through transient transfections in Smad4-negative human cancer cells and their stable Smad4-positive derivatives. Functionally relevant binding sites were subsequently confirmed through chromatin immunoprecipitation. Results: Herein, we report that Smad4 mediates transcriptional regulation through three different mechanisms, namely through Smad4 binding to a functional SBE site exclusively in the LAMA3 promoter, Smad4 binding to AP1 (and Sp1) sites presumably via interaction with AP1 family components and lastly a Smad4 impact on transcription of AP1 factors. Whereas Smad4 is essential for positive regulation of all three genes, the molecular mechanisms are significantly divergent between the LAMA3 promoter as compared to the LAMB3 and LAMC2 promoters. Conclusion: We hypothesize that this divergence in modular regulation of the three promoters may lay the ground for uncoupled regulation of Laminin-332 in Smad4-deficient tumor cells in response to stromally expressed cytokines acting on budding tumor cells
    Type of Publication: Journal article published
    PubMed ID: 18664273
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  • 8
    Keywords: EXPRESSION ; SURVIVAL ; carcinoma ; CELL ; Germany ; CLASSIFICATION ; DIAGNOSIS ; FOLLOW-UP ; RISK ; SITE ; SITES ; GENES ; PROTEIN ; TISSUE ; TUMORS ; PATIENT ; IMPACT ; IDENTIFICATION ; REGION ; RECURRENCE ; REGIONS ; SQUAMOUS-CELL CARCINOMA ; HEAD ; NECK ; pathology ; relapse ; PROTEOMICS ; PROTEOMIC ANALYSIS ; NECK-CANCER ; CELL CARCINOMA ; ONCOLOGY ; HNSCC ; PROFILES ; prospective ; SELDI-TOF-MS ; SQUAMOUS-CELL ; PROFILE ; field cancerization ; tumours ; HEAD-AND-NECK ; Follow up ; proteomic ; biomarker protein profiles ; CHROMOSOME-17 ; ORAL EPITHELIAL DYSPLASIA ; pharynx and oesophagus carcinoma
    Abstract: 'Field cancerization' in head and neck squamous cell carcinoma (HNSCC) is poorly understood and it may extend from the pharynx into the oesophagus. Both local recurrences and second primary carcinomas/second field tumours may originate from field cancerization. Our prospective pilot study aimed at the identification of patients suffering from field cancerization on the basis of mucosal protein profiles. Five mucosal biopsies from the oropharynx, hypopharynx and from three regions of the oesophagus were taken from 24 patients. Protein profiles were generated from the mucosal biopsies. After classifier learning, using the profiles of the patients without tumour diagnosis (n = 9), we were able to discriminate between the different mucosal sites and between healthy mucosa and HNSCC using tumour and healthy tissue samples. Mucosal biopsies of tumour patients (n = 15) revealed changes in the protein profiles similar to those in the tumours. During 42 months median follow-up, six tumour patients experienced local recurrences and second field tumours, of which three occurred in the oesophagus. In all six cases, tumour relapse was correctly predicted by altered mucosal protein profiles (p = 0.007, Fisher's exact test, two-tailed). Consequently, molecular field cancerization had a strong impact on progression-free survival (p = 0.007, log-rank test). Protein profiles of small diagnostic biopsies hold great promise to improve personalized risk assessment in HNSCC. Larger studies are needed to further substantiate these findings. Copyright (C) 2010 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd
    Type of Publication: Journal article published
    PubMed ID: 20593486
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  • 9
    Keywords: Germany ; TARGETS ; AUTOANTIBODIES ; neuroblastoma ; IDENTIFICATION ; TARGET ; pediatric ; pediatrics
    Type of Publication: Meeting abstract published
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  • 10
    Keywords: CANCER ; CANCER CELLS ; CELLS ; EXPRESSION ; GROWTH ; IN-VITRO ; tumor ; carcinoma ; CELL ; Germany ; human ; IN-VIVO ; MODEL ; VITRO ; VIVO ; SYSTEM ; GENE ; GENE-EXPRESSION ; GENES ; cell line ; TRANSDUCTION ; RESPONSES ; IMPACT ; INDUCTION ; tumour ; DOWN-REGULATION ; SUPPRESSION ; SIGNAL ; cytokines ; TARGET ; gene expression ; resistance ; CARCINOMA CELLS ; colorectal cancer ; COLORECTAL-CANCER ; cervical cancer ; CERVICAL-CANCER ; CELL-LINE ; LINE ; SIGNALING PATHWAY ; CANCER-CELLS ; COLORECTAL CANCERS ; EXTRACELLULAR-MATRIX ; CARCINOMA-CELLS ; SUPERFAMILY ; CERVICAL-CARCINOMA ; cervical carcinoma ; GROWTH-FACTOR-BETA ; TARGETS ; C-MYC ; OVEREXPRESSION ; pancreatic carcinoma ; HIGH-LEVEL ; CELL-GROWTH ; CYTOKINE ; MATRIX ; ONCOLOGY ; TUMOR SUPPRESSION ; LIGHT ; extracellular matrix ; RESTORATION ; regulation ; TGF-BETA ; interaction ; LEVEL ; TARGET GENES ; methods ; pancreatic ; SUPPRESSOR ; EVENTS ; tumour suppressor ; function ; LOSSES ; CANCERS ; in vivo ; SIGNALS ; carcinogenic ; COLON-CARCINOMA CELLS ; ENGLAND ; PREDICT ; colorectal ; NOV ; evidence ; cell growth ; BETAIG-H3 GENE ; BRONCHIAL EPITHELIAL-CELLS ; Smad4 ; STABLE RNA INTERFERENCE ; SUPPRESSOR E-CADHERIN ; tumour suppression
    Abstract: Background: Smad4 is a tumour suppressor frequently inactivated in pancreatic and colorectal cancers. We have recently reported loss of Smad4 in every fourth carcinoma of the uterine cervix. Smad4 transmits signals from the TGF-beta superfamily of cytokines and functions as a versatile transcriptional co-modulator. The prevailing view suggests that the tumour suppressor function of Smad4 primarily resides in its capability to mediate TGF-beta growth inhibitory responses. However, accumulating evidence indicates, that the acquisition of TGF-beta resistance and loss of Smad4 may be independent events in the carcinogenic process. Through inducible reexpression of Smad4 in cervical cancer cells we wished to shed more light on this issue and to identify target genes implicated in Smad4 dependent tumor suppression. Methods: Smad4-deficient human C4-II cervical carcinoma cells were used to establish inducible Smad4 reexpression using the commercial Tet-on (TM) system (Clontech). The impact of Smad4 reexpression on cell growth was analysed in vitro and in vivo. Transcriptional responses were assessed through profiling on cDNA macroarrays (Clontech) and validated through Northern blotting. Results: Clones were obtained that express Smad4 at widely varying levels from approximately physiological to 50-fold overexpression. Smad4-mediated tumour suppression in vivo was apparent at physiological expression levels as well as in Smad4 overexpressing clones. Smad4 reexpression in a dose-dependent manner was associated with transcriptional induction of the extracellular matrix-associated genes, BigH3, fibronectin and PAI-I, in response to TGF-beta. Smad4-dependent regulation of these secreted Smad4 targets is not restricted to cervical carcinoma cells and was confirmed in pancreatic carcinoma cells reexpressing Smad4 after retroviral transduction and in a stable Smad4 knockdown model. On the other hand, the classical cell cycle-associated TGF-beta target genes, c-myc, p21 and p15, remained unaltered. Conclusion: Our results show that Smad4-mediated tumour suppression in cervical cancer cells is not due to restoration of TGF-beta growth inhibitory responses. Rather, tumour cell-ECM interactions may be more relevant for Smad4-mediated tumour suppression. C4-II cells with a high level inducible Smad4 expression may serve as a model to indicate further Smad4 targets responsive to diverse environmental stimuli operative in vivo
    Type of Publication: Journal article published
    PubMed ID: 17997817
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