Wong, Wai Ki Vicky. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 105-131). / Abstracts in English and Chinese. / Abstract --- p.ii / 摘要 --- p.iv / Acknowledgements --- p.vi / Table of contents --- p.vii / List of tables --- p.xii / List of figures --- p.xiii / List of abbreviations --- p.xiv / Chapter Chapter 1: --- Introduction --- p.1 / Chapter Chapter 2: --- Colorectal cancer / Chapter 2.1 --- Literature Review / Chapter 2.1.1 --- Colorectal cancer --- p.8 / Chapter 2.1.2 --- Incident rate of colorectal cancer --- p.8 / Chapter 2.1.3 --- Hereditary colorectal cancer --- p.9 / Chapter 2.1.4 --- Sporadic colorectal cancer and Wnt signaling pathway --- p.10 / Chapter 2.1.5 --- Chemotherapy treatment of colorectal cancer --- p.11 / Chapter 2.1.5.1 --- 5-Fluorouracil --- p.12 / Chapter 2.1.5.2 --- Oxaliplatin --- p.14 / Chapter 2.1.5.3 --- Irinotecan --- p.14 / Chapter 2.1.6 --- Biomarkers for colorectal cancer --- p.15 / Chapter 2.1.6.1 --- Thymidylate synthase --- p.15 / Chapter 2.1.6.2 --- Dihydropyrimidine dehydrogenase --- p.16 / Chapter 2.1.6.3 --- Thymidine phosphorylase --- p.16 / Chapter 2.1.6.4 --- Microsatellite-instability status --- p.16 / Chapter 2.1.6.5 --- Clinical uses of biomarkers for colorectal cancer --- p.17 / Chapter 2.1.7 --- Choice of cell line as colorectal cancer model --- p.17 / Chapter 2.1.8 --- Aims of study --- p.17 / Chapter 2.2 --- Materials and Methods / Chapter 2.2.1 --- Verification of SW480 as a nuclear β-catenin positive cell line / Chapter 2.2.1.1 --- Maintenance of cell lines --- p.21 / Chapter 2.2.1.2 --- Antibody --- p.21 / Chapter 2.2.1.3 --- Agar block preparation for SW480 and CCD-18C0 cells --- p.22 / Chapter 2.2.1.4 --- Immunocytochemical staining --- p.22 / Chapter 2.2.2 --- Effect of anti-cancer drugs on cell viability / Chapter 2.2.2.1 --- Maintenance of cell lines --- p.22 / Chapter 2.2.2.2 --- MTT cell viability assay --- p.23 / Chapter 2.3 --- Results / Chapter 2.3.1 --- SW480 is a β-catenin positive cell line --- p.24 / Chapter 2.3.2 --- Antiproliferative effects of cytotoxic drugs in SW480 cells / Chapter 2.3.2.1 --- 5-Fluorouracil --- p.26 / Chapter 2.3.2.2 --- Oxaliplatin --- p.29 / Chapter 2.3.2.3 --- Irinotecan --- p.31 / Chapter 2.4 --- Discussion / Chapter 2.4.1 --- SW480 as a nuclear β-catenin positive cell line --- p.33 / Chapter 2.4.2 --- Antiproliferative effects of 5-fluorouracil in SW480 cells --- p.33 / Chapter 2.4.3 --- Summary --- p.34 / Chapter Chapter 3: --- Effect of 5-fluorouracil on mRNA expression in SW480 cells / Chapter 3.1 --- Literature Review / Chapter 3.1.1 --- Application of quantitative real-time polymerase chain reaction in cancer research / Chapter 3.1.1.1 --- Principles of quantitative real-time polymerase chain reaction --- p.36 / Chapter 3.1.1.2 --- Advantages of quantitative real-time polymerase chain reaction over conventional polymerase chain reaction --- p.39 / Chapter 3.1.1.3 --- Determination of colorectal cancer biomarkers by quantitative real-time polymerase chain reaction --- p.39 / Chapter 3.2 --- Materials and Methods / Chapter 3.2.1 --- Determination of the effect of 5-fluorouracil on mRNA expression in SW480 cells / Chapter 3.2.1.1 --- Treatment of cells --- p.40 / Chapter 3.2.1.2 --- Extraction of total RNA from SW480 cells --- p.40 / Chapter 3.2.1.3 --- Removal of genomic DNA --- p.41 / Chapter 3.2.1.4 --- Determination of the efficiency of genomic DNA removal --- p.42 / Chapter 3.2.1.5 --- Determination of the purity and concentration of RNA --- p.42 / Chapter 3.2.1.6 --- Determination of the integrity of RNA --- p.43 / Chapter 3.2.1.7 --- First strand cDNA synthesis --- p.44 / Chapter 3.2.1.8 --- Real-time polymerase chain reaction using human Wnt signaling pathway RT2 ProfileŕёØ PCR array --- p.44 / Chapter 3.2.1.9 --- Calculation of the fold-change in genes expression between the 5-FU treated and control SW480 cells --- p.45 / Chapter 3.3 --- Results / Chapter 3.3.1 --- The quality and quantity of RNA --- p.46 / Chapter 3.3.2 --- Effects of 5-fluorouracil on genes expression in SW480 cells --- p.48 / Chapter 3.4 --- Discussion / Chapter 3.4.1 --- Alterations in mRNA expression in 5-fluorouracil treated SW480 cells --- p.55 / Chapter 3.4.1.1 --- Extracellular signaling molecules --- p.55 / Chapter 3.4.1.2 --- Canonical Wnt signaling pathway --- p.56 / Chapter 3.4.1.3 --- Regulators of cell cycle --- p.57 / Chapter 3.4.1.4 --- Regulators of growth and proliferation --- p.58 / Chapter 3.4.1.5 --- Regulators of transcription --- p.58 / Chapter 3.4.1.6 --- Regulators of Wnt receptor signaling pathway --- p.60 / Chapter 3.4.1.7 --- Other genes involved in Wnt signaling --- p.61 / Chapter 3.4.2 --- Limitations of Q-RT-PCR --- p.61 / Chapter 3.4.3 --- Summary --- p.62 / Chapter Chapter 4: --- Effect of 5-fluorouracil on proteins expression in SW480 cells / Chapter 4.1 --- Literature Review / Chapter 4.1.1 --- From mRNA to proteins --- p.63 / Chapter 4.1.2 --- Application of proteomics in cancer research --- p.63 / Chapter 4.1.3 --- Two-dimensional gel electrophoresis --- p.64 / Chapter 4.1.4 --- Principles of MALDI TOF mass spectrometry --- p.64 / Chapter 4.1.5 --- Peptide mass fingerprinting --- p.65 / Chapter 4.1.6 --- Drug response proteins detected by proteomics in colorectal cancer cell lines --- p.65 / Chapter 4.1.7 --- Detection of biomarker in colorectal cancer formation using proteomics --- p.66 / Chapter 4.2 --- Materials and Methods / Chapter 4.2.1 --- Determination of the effect of 5-fluorouracil on proteins expression in SW480 cells / Chapter 4.2.1.1 --- Treatment of cells --- p.67 / Chapter 4.2.1.2 --- Cell lysis --- p.67 / Chapter 4.2.1.3 --- Protein quantitation of cell lysate --- p.67 / Chapter 4.2.1.4 --- Sample preparation for two-dimensional electrophoresis --- p.68 / Chapter 4.2.1.5 --- Two-dimensional electrophoresis --- p.69 / Chapter 4.2.1.6 --- Silver staining --- p.69 / Chapter 4.2.1.7 --- Image analysis --- p.70 / Chapter 4.2.1.8 --- In-gel protein digestion --- p.70 / Chapter 4.2.1.9 --- Peptide mass fingerprinting using mass spectrometry --- p.71 / Chapter 4.3 --- Results / Chapter 4.3.1 --- Protein expression patterns of 5-fluorouracil treated and untreated SW480 cells by 2-dimensional electrophoresis --- p.72 / Chapter 4.3.2 --- Identification of the differentially expressed proteins after 5-fluorouracil treatment in SW480 cells --- p.75 / Chapter 4.4 --- Discussion / Chapter 4.4.1 --- Effects of 5-fluorouracil on protein expression in SW480 cells --- p.82 / Chapter 4.4.1.1 --- Identified upregulated proteins after 5-fluorouracil treatment in SW480 cells / Chapter 4.4.1.1.1 --- Cyclophilin A --- p.83 / Chapter 4.4.1.1.2 --- Cytokeratin 19 --- p.83 / Chapter 4.4.1.1.3 --- Cytokeratin 8 --- p.84 / Chapter 4.4.1.1.4 --- RAN --- p.84 / Chapter 4.4.1.1.5 --- Heat shock protein 27 --- p.84 / Chapter 4.4.1.1.6 --- Peroxiredoxin 6 --- p.85 / Chapter 4.4.1.2 --- Identified dowiiregulated proteins after 5-fluorouracil treatment in SW480 cells / Chapter 4.4.1.2.1 --- Heat shock protein 60 --- p.86 / Chapter 4.4.1.2.2 --- Cytokeratin 18 --- p.86 / Chapter 4.4.1.2.3 --- Cytokeratin 9 --- p.86 / Chapter 4.4.1.2.4 --- Carbamoylphosphate synthetase I --- p.87 / Chapter 4.4.1.2.5 --- a-Enolase --- p.87 / Chapter 4.4.1.2.6 --- Heat shock protein 70 --- p.87 / Chapter 4.4.1.2.7 --- nm23 --- p.88 / Chapter 4.4.1.2.8 --- β-actin --- p.88 / Chapter 4.4.2 --- Limitations of proteomics profiling --- p.89 / Chapter 4.4.3 --- Summary --- p.90 / Chapter Chapter 5: --- Verification of proteinśة identities by immunocytochemical staining / Chapter 5.1 --- Materials and Methods / Chapter 5.1.1 --- Antibodies --- p.91 / Chapter 5.1.2 --- Treatment of cells --- p.91 / Chapter 5.1.3 --- Agar block preparation of SW480 cells --- p.92 / Chapter 5.1.4 --- Immunocytochemical staining and evaluation --- p.92 / Chapter 5.1.5 --- Polymer-based immunohistochemical detection system --- p.93 / Chapter 5.1.6 --- Statistical analyses --- p.93 / Chapter 5.2 --- Results / Chapter 5.2.1 --- Confirmation of proteomic findings using immunocytochemical stainings in paraffin-embedded sections of 5-fluorouracil treated and untreated SW480 cells --- p.94 / Chapter 5.3 --- Discussion / Chapter 5.3.1 --- Immunocytochemical staining to verify proteomics findings of 5-fluorouracil treated and untreated SW480 cells --- p.99 / Chapter 5.3.2 --- Limitations of ICC staining --- p.100 / Chapter 5.3.3 --- Summary --- p.100 / Chapter Chapter 6: --- Conclusions and future perspectives / Chapter 6.1 --- Significance of study --- p.101 / Chapter 6.2 --- Future perspectives --- p.102 / References --- p.105

<p>Transforming growth factor-β (TGF-β) is a member of a large superfamily of cytokines which participate in many different types of cellular processes, such as growth inhibition, cell migration, differentiation, cell adhesion, wound healing and immunosuppression. Alterations of TGF-β superfamily signalling results in several different disorders, including bone disease, vascular disease and cancer. The TGF-β signalling pathways involve several different proteins, such as the Smad proteins, which upon receptor activation are translocated to the nucleus, where they affect transcriptional responses. </p><p>The actin cytoskeleton is an organised network of filaments with a highly dynamic structure, which is under a continuous reconstruction to control the morphology, survival, growth and motility of eukaryotic cells. The members of the family of small GTP-binding proteins have been shown to be important regulators of the actin cytoskeleton.</p><p>TGF-β was found to induce short term as well as long term actin reorganisation in prostate cancer cells. The short term response included membrane ruffling, and required signalling by the small GTPases Cdc42 and Rho as well as, the involvement of the mitogen-activated protein kinases p38 (p38 MAPK). The long term response included formation of stress fibers and required a cooperation between Smad and Rho GTPase signalling pathways involving the Rho-associated coiled-coil-containing protein kinase 1 (ROCK1). </p><p>The TGF-β-induced activation of Cdc42 was, furthermore, shown to require the inhibitory Smad7 and p38 MAP kinase, via a PI3K-dependent pathway. Mixed lineage kinase 3 (MLK3), a mediator downstream of Cdc42, was necessary for the Cdc42-dependent actin filament reorganisation.</p><p>Apoptosis is an important and carefully regulated process in human development and disease, which allows the multicellular organisms to remove cells that are in excess or potentially dangerous. TGF-β family members can induce apoptosis in many different cell types, in the presence or absence of other growth factors. Smad7 had previously been shown to be necessary for TGF-β-induced apoptosis of epithelial cells. We could show that Smad7 is required for TGF-β-induced activation of the TGF-β activated kinase 1 (TAK1)-mitogen-activated protein kinase kinase 3 (MKK3)-p38 MAPK pathway, which subsequently leads to apoptosis in prostate cancer cells.</p><p>Members of the lymphoid enhancer factor-1/T-cell factor (LEF1/TCF) family of transcription factors have, together with β-catenin, been shown to be nuclear effectors in the Wnt-signalling pathway. We investigated a possible cross-talk between the TGF-β and Wnt signalling pathways. We found that TGF-β, in a Smad7-dependent manner induced a nuclear accumulation of β-catenin and enhanced the transcriptional activity of β-catenin and the induction of the downstream target gene <i>c-myc</i>. Since β-catenin and c-Myc has been shown to promote apoptosis, our results suggests the possibility that β-catenin contributes to TGF-β-induced apoptosis</p>

Transforming growth factor-β (TGF-β) is a member of a large superfamily of cytokines which participate in many different types of cellular processes, such as growth inhibition, cell migration, differentiation, cell adhesion, wound healing and immunosuppression. Alterations of TGF-β superfamily signalling results in several different disorders, including bone disease, vascular disease and cancer. The TGF-β signalling pathways involve several different proteins, such as the Smad proteins, which upon receptor activation are translocated to the nucleus, where they affect transcriptional responses. The actin cytoskeleton is an organised network of filaments with a highly dynamic structure, which is under a continuous reconstruction to control the morphology, survival, growth and motility of eukaryotic cells. The members of the family of small GTP-binding proteins have been shown to be important regulators of the actin cytoskeleton. TGF-β was found to induce short term as well as long term actin reorganisation in prostate cancer cells. The short term response included membrane ruffling, and required signalling by the small GTPases Cdc42 and Rho as well as, the involvement of the mitogen-activated protein kinases p38 (p38 MAPK). The long term response included formation of stress fibers and required a cooperation between Smad and Rho GTPase signalling pathways involving the Rho-associated coiled-coil-containing protein kinase 1 (ROCK1). The TGF-β-induced activation of Cdc42 was, furthermore, shown to require the inhibitory Smad7 and p38 MAP kinase, via a PI3K-dependent pathway. Mixed lineage kinase 3 (MLK3), a mediator downstream of Cdc42, was necessary for the Cdc42-dependent actin filament reorganisation. Apoptosis is an important and carefully regulated process in human development and disease, which allows the multicellular organisms to remove cells that are in excess or potentially dangerous. TGF-β family members can induce apoptosis in many different cell types, in the presence or absence of other growth factors. Smad7 had previously been shown to be necessary for TGF-β-induced apoptosis of epithelial cells. We could show that Smad7 is required for TGF-β-induced activation of the TGF-β activated kinase 1 (TAK1)-mitogen-activated protein kinase kinase 3 (MKK3)-p38 MAPK pathway, which subsequently leads to apoptosis in prostate cancer cells. Members of the lymphoid enhancer factor-1/T-cell factor (LEF1/TCF) family of transcription factors have, together with β-catenin, been shown to be nuclear effectors in the Wnt-signalling pathway. We investigated a possible cross-talk between the TGF-β and Wnt signalling pathways. We found that TGF-β, in a Smad7-dependent manner induced a nuclear accumulation of β-catenin and enhanced the transcriptional activity of β-catenin and the induction of the downstream target gene c-myc. Since β-catenin and c-Myc has been shown to promote apoptosis, our results suggests the possibility that β-catenin contributes to TGF-β-induced apoptosis

Ptf1a/p48 is a pancreas specific bHLH transcription factor that is required at early stages of embryonic development for pancreas formation and, during adulthood, for the proper exocrine pancreatic function. P48 also exerts an antiproliferative effect, which may exert a tumor suppressor activity. In this study, based on a yeast two-hybrid approach, we have identified new p48 partners that modulate the activity of p48. Among the newly identified putative interactors we found p/CAF, which is a coactivator that potentiates its transcriptional activity, and ICAT, an inhibitor of the &#946;-catenin/TCF signaling pathway. ICAT binds to p48 and is coexpressed with it in the pancreas during development and postnatally. Using different cellular models, ICAT overexpression in acinar tumor cells resulted in changes of the pancreatic specific gene expression pattern. Furthermore, high levels of ICAT inhibited the interaction between p48 and p/CAF. While this hetero-oligomeric complex is required for the acinar gene expression, ICAT itself is shown to be present in a reconstituted PTF1 complex in vivo. Importantly, altered ICAT expression is demonstrated in several histological types of pancreatic tumors, possibly contributing to their differentiation phenotype and neoplastic properties. / Ptf1a/p48 es un factor de transcripción bHLH específico del páncreas necesario durante los estadios tempranos del desarrollo embrionario para la formación del mismo, y para el correcto funcionamiento del páncreas exocrino en el adulto. P48 desempeña también una función antiproliferativa, la cual puede resultar en una actividad de supresión tumoral. En el presente estudio, basado en una estrategia de cribado de doble-híbrido en levadura, han sido identificadas nuevas proteínas que interaccionan y que modulan la actividad específica de p48. Entre las posibles proteínas que interaccionan y han sido identificadas de novo se encuentra p/CAF, un co-activador que potencia la actividad transcripcional de p48, y ICAT, un inhibidor de la vía de señalización de la &#946;-catenina. Se ha demostrado que ICAT se une a p48 y ambos son co-expresados en el páncreas durante el desarrollo y en el adulto. Utilizando diferentes modelos celulares, la sobreexpresión de ICAT en células tumorales acinares resultó en un cambio en el patrón de expresión de genes específicos del páncreas. Al mismo tiempo, se observó que niveles elevados de ICAT inhiben la interacción entre p48 y su co-activador p/CAF. Mientras que este complejo hetero-oligomérico es necesario para la expresión de los genes acinares, se demostró que ICAT está presente en un complejo PTF1 reconstituido in vivo. Finalmente, se observaron alteraciones en la expresión de ICAT en varios tipos histológicos de tumores pancreáticos, que posiblemente contribuyen a su fenotipo de diferenciación y propiedades neoplásicas.

Made available in DSpace on 2016-12-23T13:54:30Z (GMT). No. of bitstreams: 1 Regina Furbino Villefort Rocha.pdf: 5172514 bytes, checksum: a4a9d38bcac502c5c9c1fe6298995e29 (MD5) Previous issue date: 2012-07-04 / Ameloblastomas são tumores odontogênicos (TOs) de origem epitelial e etiologia desconhecida. Porém, estudos recentes identificaram alterações moleculares associadas ao desenvolvimento e progressão dos TOs, dentre elas as móleculas de adesão celular E-caderina e beta catenina. Objetivos: realizar um levantamento epidemiológico dos casos de ameloblastomas pertencentes ao arquivo do Serviço de Anatomia Patológica da Universidade Federal do Espírito Santo (SAPB-UFES), analisar suas características histopatológicas e a expressão de beta catenina nas diferentes variantes de ameloblastomas. Método: estudo retrospectivo dos casos de ameloblastomas registrados no SAPB-UFES, no período compreendido entre março de 2004 e dezembro de 2010. Foram coletados dados sociodemográficos, clinicorradiográficos, dados sobre acesso, diagnóstico, tratamento e seguimento desses pacientes. As análises histopatológicas foram baseadas nos critérios de Vickers e Gorlin, Waldron e El-Mofty e da Organização Mundial da Saúde. Para análise imuno-histoquímica foi utilizada a técnica indireta de imuno-peroxidase, com anticorpo primário anti beta catenina monoclonal de camundongo. Foram avaliados a intensidade e a localização da marcação. Para análise semiquantitativa foram adotados os escores: negativo, postividade focal, positividade variável e uniformidade positiva. Resultados: foram encontrados 13 ameloblastomas, classificados histopatologicamente como sólidos (06), unicísticos (03) e desmoplásicos (03). Todos foram imunomarcados. A intensidade de marcação variou de fraca a forte (1 a 3). A média de marcação variou de 10,82% a 13,38% no núcleo; de 39,93% a 47,61% na membrana; e de 90,01% a 98,53% no citoplasma. Entretanto não foi encontrada diferença significante de expressão de beta catenina entre os três diferentes tipos de ameloblastomas. Conclusão: os resultados epidemiológicos foram semelhantes a outros estudos. A expressão citoplasmática de beta catenina evidencia o acúmulo da mesma no citoplasma e sugere alteração na via de sinalização de Wnt. Por outro lado, a redução da expressão na membrana sugere alteração na adesão celular / Ameloblastomas are odontogenic tumors (OTs) derived from epithelium which etiology remains unknown. However, recent studies have identified molecular changes associated with the development and progression of OTs, including cell adhesion molecules like E-cadherin and beta-catenin. Objectives: to conduct an epidemiological investigation of ameloblastomas cases from files of the Anatomical Pathology Service at Federal University of Espírito Santo (SAPB-UFES), analyze their histopathological features and the expression of beta-catenin in different variants of ameloblastomas. Methods: a retrospective study of ameloblastomas registered at SAPB-UFES between March 2004 and December 2010. Sociodemographic, clinical and imaginological data were collected, as well as data about access, diagnosis, treatment and follow up of these patients. The histopathological analyzes were based on Vickers and Gorlin, Waldron and El-Mofty and the World Health Organization criteria. Primary antibody anti beta-catenin mouse monoclonal and indirect immuno-peroxidase technique was employed for immunohistochemical analysis. Intensity and location of the immunostaining were analysed. For semiquantitative analysis the scores were: negative, focal, variable and uniformity positivity. Results: there were 13 ameloblastomas, histopathologically classified as solid (06), unicystic (03) and desmoplastic (03). All of them were immunostained. The intensity of immunostaining ranged from weak to strong (1-3). The mean of immunostaining ranged from 10.82% to 13.38% in the nucleus; from 39.93% to 47.61% in the membrane; and from 90.01% to 98.53% in the cytoplasm. However, there was no significant difference in expression of beta-catenin between three different types of ameloblastomas. Conclusion: The results were similar to other epidemiological studies. The cytoplasmic expression of beta-catenin shows accumulation in the cytoplasm and suggests changes in the Wnt signaling pathway. Moreover, the reduction of membrane expression suggests changes in cell adhesion

No description available.

Os craniofaringiomas são os tumores mais frequentes da região hipotálamohipofisária na faixa etária pediátrica. Apesar de serem histologicamente benignos, sua tendência infiltrativa e seu comportamento agressivo resultam em significante morbimortalidade. Histologicamente podem ser divididos em dois subtipos: adamantinomatosos e papilíferos. A patogênese dos craniofaringiomas é pouco compreendida. Mutações no gene CTNNB1, que codifica a proteína beta-catenina, são a única alteração molecular conhecida até o momento implicada na tumorigênese dos craniofaringiomas adamantinomatosos. Tais mutações afetam o sítio de degradação da beta-catenina, que passa a se acumular no citoplasma e no núcleo, ativando excessivamente a via de sinalização WNT, através da ligação aos fatores de transcrição da família LEF/TCF, levando a tumorigênese. Recentemente foi descoberto um novo mecanismo de determinação da linhagem celular hipofisária regulado pela beta-catenina, através do qual ela interage diretamente com o PROP1 para determinar a diferenciação celular hipofisária. De acordo com esse modelo, o complexo protéico PROP1/beta- catenina atua simultaneamente como repressor do HESX1 e ativador do PIT1, dependendo dos co-fatores associados. Pacientes com mutações germinativas inativadoras no PROP1 desenvolvem hipopituitarismo e podem apresentar aumento hipofisário com imagens de ressonância nuclear magnética (RNM) da região selar muitas vezes semelhantes àquelas dos craniofaringiomas, com hiperssinal em T1. Por outro lado, camundongos com expressão persistente do Prop1 exibem defeitos na regulação da proliferação celular hipofisária, incluindo cistos da bolsa de Rathke, hiperplasia adenomatosa e tumores, sugerindo que mutações com ganho de função no PROP1 também poderiam contribuir para a patogênese de tumores hipofisários em seres humanos. A semelhança entre as imagens de RNM dos pacientes com craniofaringiomas e daqueles com aumento hipofisário devido a mutações inativadoras no PROP1, e o fato de que camundongos transgênicos com expressão persistente do Prop1 apresentam aumento da susceptibilidade a tumores hipofisários, deram base a nossa hipótese de que uma desregulação na expressão do PROP1 em humanos poderia estar envolvida na patogênese dos craniofaringiomas adamantinomatosos. Esse trabalho teve como objetivo avaliar a presença de mutação somática no exon 3 do CTNNB1 e avaliar a expressão desse gene e do gene PROP1 em craniofaringiomas adamantinomatosos. Foram obtidas 14 amostras desse tipo de tumor por meio da ressecção terapêutica. As amostras foram submetidas à extração do RNA e posterior transcrição reversa para obtenção de cDNA. A partir do cDNA foi realizada PCR e sequenciamento do exon 3 do CTNNB1 em todas as amostras. Porém, a avaliação por PCR em tempo real foi realizada apenas em 12 amostras, devido à qualidade inadequada de 2 amostras para submissão a essa metodologia. Foram encontradas mutações missense, em heterozigose em 9 das 14 amostras, sendo 5 previamente descritas e 2 ainda não descritas em craniofaringiomas adamantinomatosos. Hiperexpressão do CTNNB1 foi encontrada em 7 amostras, sendo 5 com mutação e 2 sem mutação no CTNNB1.A hiperexpressão variou de 2,5 a 6,2 vezes maior que o pool de hipófise normal. Contudo, a expressão do PROP1 foi indetectável em todas as amostras. Concluímos que o aumento da expressão do CTNNB1 presente em 58% das amostras sugere o envolvimento também da hiperexpressão desse gene na etiopatogenia do craniofaringioma adamantinomatoso, enquanto a ausência de expressão do PROP1 afasta a participação desse gene na etiopatogenia do craniofaringioma adamantinomatoso / Craniopharyngiomas are the the commonest tumors to involve the hypothalamo-pituitary regions in childhood population. Histologically they are benign, and can be divided in two primary subtypes: the adamantinomatous and the papillary. Although histologically benign, their infiltrative tendency and aggressive behavior can result in great morbidity. The pathogenesis of craniopharyngiomas is poorly understood. To date, beta-catenin gene (CTNNB1) mutations have been identified only in the adamantinomatous subtype. These mutations affect the degradation target box of beta-catenin that accumulates in the cytoplasm and the nucleus increasing the transcriptional activity of WNT pathway through interaction with the transcription factors of LEF/TCF family, leading to tumorigenesis. Recently, an interaction between beta-catenin and PROP1 was described as a new mecanism for beta-catenindependent regulation of pituitary cell-lineage determination. According to this novel model, the PROP1/beta-catenin proteic complex would act as a binary switch to simultaneously repress the transcription factor HESX1 and to activate expression of transcription factor PIT1, depending on the associated cofactors. Patients with loss-of-function mutations in PROP1 present combined pituitary hormonal deficiency generally associated with pituitary enlargement and the magnetic resonance imaging (MRI) of the sellar region in these patients sometimes resembles that of the craniopharyngiomas, with T1 hyperintense signal. On the other hand, transgenic mice with persistent Prop1 expression exhibit defects consistent with misregulation of pituitary cell proliferation, including adenomatous hyperplasia with formation of Rathke\'s cleft cysts and tumors suggesting that misregulation of PROP1 expression in human could contribute to pathogenesis of pituitary tumors. The similarity between the MRI images of craniopharyngiomas patients and that of patients with loss-of-function mutations in PROP1, associated with the fact that transgenic mice with persistent Prop1 expression exhibit increased susceptibility to pituitary tumors gave rise to our hypothesis that a misregulation of PROP1 expression could be involved in the pathogenesis of adamantinomatous craniopharyngiomas. The aim of this study was to analyze the presence of somatic mutations in exon 3 of CTNNB1 and the expression pattern of this gene and the PROP1 gene in adamantinomatous craniopharyngiomas. Fourteen samples were obtained from therapeutic surgery and submitted to RNA extraction and reverse transcription in order to produce the cDNA. The cDNA was used as a template to CTNNB1 exon 3 PCR reaction followed by direct sequencing of all samples. However, the real-time RT-PCR analysis was realized only in 12 samples, since 2 of them had an insufficient quality for this method. Missence, heterozygous mutations were found in 9 out of 14 samples; five were previously described and 2 not yet described in adamantinomatous craniopharyngiomas. Overexpression of CTNNB1 was found in 7 samples, which them 5 with CTNNB1 mutation 2 whitout. The overexpression ranged from 2.5 to 6.2 fold more than pituitary normal pool. However, the PROP1 expression was undetectable in all the samples. We could conclude that the amount of 58% CTNNB1 overexpressed samples suggest also a role of this overexpression in the pathogenesis of adamantinomatous craniopharingiomas, while the undetectable levels of PROP1 exclude a role of this gene in the pathogenesis of adamantinomatous craniopharingiomas

A via canônica Wnt/beta-catenina regula várias funções em vertebrados, incluindo diferenciação de células T, bem como a proliferação, sobrevivência, morfogênese e migração de vários tipos celulares. As células T CD4+ é fundamental para a competência imunológica. Foi observado pelo nosso grupo que células T CD4+ humanas apresentam ativação da via Wnt/beta-catenina após tratamento com sais de lítio ou outros agonistas da via. A ativação desta via induziu a proliferação de células T CD4+ naive e de memória central. Em conjunto, estes dados sugerem um importante papel da via Wnt/beta-catenina na homeostase de células T CD4+ humanas. Seria importante avaliar o papel da via Wnt/beta-catenina nas células do sistema imune no modelo murino, já que pouco se sabe sobre seu efeito na homeostase de células T CD4+ murinas. A ativação da via Wnt/beta-catenina pode ser induzida com inibidores da proteína Glicogênio sintase quinase 3beta (GSK3beta), por exemplo, os sais de lítio (LiCl e Li2CO3) e inibidores específicos (SB, CHIR) em vários tipos celulares. Neste trabalho, avaliamos o efeito de inibidores de GSK3? na ativação da via Wnt/beta-catenina canônica em esplenócitos e células T CD4+, através da realização de experimentos in vivo e in vitro, avaliando a expressão de seus genes alvo HIG2, Bcl-xL, Ciclina D1 e c-myc. Verificou-se que o tratamento in vivo agudo (2-12 h após a administração) ou crônico (administração diária por 30 dias) de camundongos não é capaz de ativar a via Wnt/beta-catenina in vivo em células esplênicas e células T CD4+, embora o mesmo tratamento induza a expressão dos genes alvo da via no tecido cerebral (córtex e hipocampo). Além disso, também não foi possível verificar ativação da via em esplenócitos e células T CD4+ após tratamento in vitro das mesmas com LiCl ou os inibidores específicos de GSK3beta testados(CHIR99021, SB-216763), embora essa ativação tenha sido observada na linhagem celular HEK293. Nossos resultados sugerem que a via Wnt/beta-catenina (canônica) não é induzível em células T CD4+ murinas maduras, com os agonistas testados. Isso pode ter implicações fisiológicas, por exemplo sobre a homeostase de células T CD4+, já que a proliferação homeostática de células T, influenciada em humanos pela via Wnt/beta-catenina, é menos importante em camundongos / The Wnt/beta-catenin pathway regulates many functions in vertebrates, including T cell differentiation, as well as proliferation, morphogenesis and migration in different cell types. CD4+ T cells play is fundamental for immunological competence. Our group has observed that human CD4+ T cells present activation of the Wnt/beta-catenin pathway after treatment with lithium salts or other pathway agonists. The activation of this pathway induced proliferation in naive and central memory CD4+ T cells. Together, these results suggest an important role for the Wnt/beta-catenin pathway in the homeostasis of human CD4+ T cells. It would be very important to evaluate the role of the Wnt/beta-catenin pathway in T cells in the mouse model, since little is known about its effect in mice CD4+ T cell homeostasis. The activation of the Wnt/beta-catenin pathway may be induced with Glycogen Synthase Kinase 3B (GSK3beta) inhibitors, i.e., lithium salts as mentioned above, and specific GSK3beta inhibitors (SB, CHIR) in different cell types. In this work, we evaluated the effect of GSK3beta inhibitors in the activation of the canonical Wnt/beta-catenin in splenocytes and CD4+ T cells, by conducting experiments in vivo and in vitro, evaluating the expression of its target genes HIG2, Bcl-xL, Cyclin D1 and c-myc. We verified that acute (2-12 hours after administration) or chronic (daily administration for 30 days) treatment of mice with lithium salts is not able to activate the Wnt/beta-catenin pathway in splenocytes and CD4+ T cells, although we could observe activation in brain tissues (cortex and hypothalamus). Besides, no activation of the Wnt/beta-catenin pathway was observed in these cell types after in vitro treatment with LiCl or the specific inhibitors of GSK3beta (CHIR99021, SB-216763), while the pathway was activated by the same treatments in HEK293 cells. Our results suggest that the Wnt/beta-catenin pathway is not inducible in murine mature CD4+ T cells with the tested agonists. This may have physiological implications, for instance on the homeostasis of CD4+ T cells, where homeostatic proliferation - influenced the Wnt/beta-catenin pathway in human T cells - is less important in the maintenance of the murine peripheral T cell pool

Contexte: Le carcinome hépatocellulaire (CHC) est la plus fréquent des tumeurs primitives du foie. Près de 50% des CHC sont causés par une infection par le virus de l'hépatite B (VHB). Au cours des différents stades de l’infection par le VHB, des multiples altérations génétiques et/ou chromosomiques s'accumulent et favorisent ainsi le développement tumoral. Objectives: a) étudier, in vitro et in vivo, le rôle potentiel d’un nouveau gène susceptible d’être impliqué dans la carcinogénèse hépatique : IRF-2 (Interferon regulatory factor 2). Ce gène a été identifié comme fréquemment délété par analyse CGH-SNP dans les CHC liés à l’infection par le VHB. b) caractériser une série de CHC liés au VHB en étudiant le statut viral, les altérations génétiques et l’expression de différents gènes afin de mieux comprendre le rôle du VHB dans l’hépato-carcinogenèse et comparer ces différents paramètres avec une série de CHC non liés au VHB. Résultats : a) Dans une série de 125 CHC, Sandrine Imbeaud, au sein du laboratoire, a effectué une analyse CGH-SNP microarray et a identifié une région commune de délétion homozygote localisée en 4q34.3-35 comprenant le gène IRF-2 dans 4 échantillons. Nous avons ensuite mis en évidence par séquençage des mutations somatiques inactivatrices dans 2 autres tumeurs. In vitro, la sousexpression d’IRF-2 a entrainé une augmentation de la prolifération cellulaire et sa sur-expression a induit une promotion de l'apoptose cellulaire. In vivo, l’extinction d’IRF-2 était responsable de la formation de tumeurs de grande taille. Les 6 tumeurs inactivées pour IRF-2 étaient associées au VHB (p = 0.0003), et les mutations de TP53 et d’IRF-2 étaient mutuellement exclusives. La sousexpression de IRF-2 induisait une sous-expression de TP53 et une forte corrélation entre les expressions protéiques de p53 et de IRF-2 a été observée (r2 = 0,72, p = 0,004). En plus, on a observé que l’expression des gènes cibles directs de TP53 était modulée par le niveau d‘expression d’IRF-2. Nous avons émise l'hypothèse que IRF-2 pourrait altérer la fonction de p53 car IRF-2 est connue pour se lier à MDM2, un régulateur négatif de l’expression de p53. Le traitement des cellules inactivées pour IRF-2 avec MG132, un inhibiteur du protéasome, a induit la restauration de l'expression de p53. In vivo, le traitement avec bortézomib, un inhibiteur du proteasome utilisé en oncologie, a entrainé une régression des tumeurs inactivées pour IRF-2. b) Nous avons caractérisé sur le plan clinique et moléculaire une série de CHC liés au VHB et, ensuite, nous avons comparé nos résultats avec ceux d’une série de CHC liés à autres étiologies. Nous avons montré que les CHC liés au VHB présentaient des caractéristiques cliniques et pathologiques différentes de celles des CHC non liés au VHB : ils survenaient chez des patients plus jeunes (P < 0.0001), d'origine Africaine ou Asiatique (P < 0.0001), avec un taux sérique d'alpha-foeto protéine élevé (P = 0.008) et étaient sur le plan histologique des tumeurs peu différenciés (P = 0.04). Nous avons identifié des mutations inactivatrices du gène HBX dans 71% des tumeurs et dans 33% des tissus non tumoraux adjacents (P < 0.0001). Dans 63% des cas, le nombre de copies virales dans les tumeurs était plus faible que dans les tissus non tumoraux adjacents (P < 0.0001). Le gène TP53 était le gène le plus fréquemment muté dans les CHC liés au VHB (41%, P = 0.0002), avec des mutations R249S présentes dans 14 échantillons (16%, p < 0.0001). Ce type de mutation est classiquement associé à l'aflatoxine B1. Nous avons observé que les mutations de TP53 étaient un prédicteur indépendant de survie uniquement pour les patients infectés par le VHB. Enfin, ... / Pas de résumé en anglais / Introduzione: Il carcinoma epatocellulare (HCC) è il tumore primitivo più comune del fegato. Nel mondo, quasi il 50% di tutti gli HCC sono causati dal virus dell'epatite B (HBV). Durante le fasi dell’ infezione da HBV, si possono accumulare alterazioni genetiche e / o cromosomiche e quindi promuovere lo sviluppo del tumore. Obiettivi: a) analizzare in vitro e in vivo il ruolo potenziale di un nuovo gene potenzialmente coinvolto nella carcinogenesi epatica: IRF-2 (Interferon regulatory factor 2). Questo gene è stato identificato mediante l’analisi CGH-SNP come frequentemente deleto negli HCC correlati all’ HBV. b) caratterizzare una cohorte di HCC correlati all’HBV studiandone lo stato virale, le alterazioni genetiche e l’espressione di differenti geni al fine di comprendere meglio il ruolo di HBV nella carcinogenesis epatocellulare e confrontare questi parametri con una cohorte di HCC a diversa eziologia. Risultati: a) In laboratorio, Sandrine Imbeaud ha condotto un'analisi SNP-CGH microarray su una cohorte di 125 HCC che ha evidenziato una regione deleta in maniera omozigote localizzata sul braccio lungo del cromosoma 4 (4q34.3-35) in 4 campioni tumorali. La regione comprende un unico gene: IRF2. In altri due campioni sono state identificate mutazioni somatiche inattivatrici mediante sequenziamento della regione codante di IRF-2. In vitro, la soppressione di IRF-2 ha indotto un aumento della proliferazione cellulare, al contrario, la sua sovra-espressione ha causato un aumento dell’apoptosi cellulare. In vivo, la soppressione di IRF-2 è responsabile della formazione di tumori più grandi nei topi nude. I 6 tumori mutati per IRF2 sono tutti correlati all’ HBV (p = 0,0003. Nella cohorte di tumori studiati, le mutazioni di TP53 e di IRF-2 erano vicendevolmente esclusive. Inoltre, la soppressione dell’espressione della proteina IRF-2 induceva una riduzione dell’espressione della proteina p53 ed una stretta correlazione tra l’espressione delle due proteine è stata osservata (r2 = 0,72, p = 0,004). Inoltre, abbiamo dimostrato che il livello di espressione di IRF-2 è in grado di modulare l'espressione di alcuni geni target di TP53. Abbiamo, quindi, ipotizzato che IRF2 possa alterare la funzione di p53. Come è noto IRF2 può legarsi a MDM2, un regolatore negativo di p53 che induce la sua degradazione proteasomica. Il trattamento di cellule inattivate per IRF2 con MG132, un inibitore del proteasoma, induceva il restauro dell’espressione di p53. In vivo, il trattamento con bortezomib, chemioterapico inibitore del proteasoma, ha determinato la regressione del tumore inattivato per IRF2. b) 86 HCC correlati all’HBV sono stati caratterizzati dal punto di vista clinico e molecolare ed in seguito sono stati confrontati una serie di 90 HCC correlati ad altre eziologie. Gli HCC correlati all’HBV hanno delle caratteristiche cliniche e patologiche diverse da quelle degli HCC d’altra eziologia: insorgenza in pazienti più giovani (p <0,0001), di origine africana o asiatica (P <0.0001), alfa-fetoproteina sierica elevata (P = 0.008) e scarsa differenziazione istologica (P = 0,04). Mutazioni inattivatrici del gene HBX sono state identificate nel 71% dei tumori e il 33% dei tessuti non tumorali adiacenti (P <0.0001). Nel 63% dei casi, il numero di copie virali nel tessuto tumorale era inferiore rispetto al tessuto non tumorale adiacente (p <0,0001). Il gene TP53 è stato il gene più frequentemente mutato nella serie di HCC correlati a HBV (41%, p = 0,0002), con una considerevole presenza di mutazioni al codone 249 (R249S) (16%, p <0,0001). Questo tipo di mutazione è associate classicamente all’ aflatossina B1. Abbiamo osservato, inoltre, che TP53 mutato era un predittore indipendente di sopravvivenza solo per i pazienti infetti da HBV. Infine, ...

Insulin-like growth factor binding proteins (IGFBPs) modulate the bioavailability of IGFs in circulation. IGFBPs 1-6 bind IGFs with high affinity and can either potentiate or inhibit IGF signaling in a context dependent manner. IGFBP2 is a 36 kDa protein and the second most abundant IGFBP in serum. Numerous studies in the recent past have implied a pro-tumorigenic role of IGFBP2. Elevated expression of IGFBP2 has been observed in multiple malignancies, including glioblastoma multiforme (GBM), ovarian, pancreatic, gastric, prostate, colon, breast, thyroid cancer and leukemia. In addition, increased expression of IGFBP2 in both tissues and serum of patients has been correlated with poor prognosis in prostate, glioblastoma and colon cancers. Pro-tumorigenic actions of IGFBP2 have been supported by in vitro studies, where IGFBP2 increases the tumorigenic potential of adrenocortical tumor cells, epidermoid carcinoma cells, glioma cells and ovarian cancer cells. Further, using xenograft animal models, the role of IGFBP2 in the progression of glioma has been established. In breast cancer, IGFBP2 was found to be over expressed in ductal carcinoma in situ and invasive breast cancer samples. IGFBP2 over expression has been shown to confer drug resistance and an increased expression has been reported to correlate with lymph node metastasis in T1 breast carcinomas. These reports implicate IGFBP2 in breast cancer biology. However, its role in breast cancer progression is not well defined. With this background, the following objectives were set for the current study: Functional characterization of IGFBP2 with respect to its possible role in breast cancer progression. Elucidation of the molecular mechanisms of IGFBP2 actions. Towards this, immunohistochemistry was performed on 132 invasive ductal carcinoma (IDC) grade III tumors using IGFBP2 specific antibody. It was observed that IGFBP2 expression was significantly higher in tumors in comparison to normal tissues that showed no detectable staining for IGFBP2. It was also observed that expression of IGFBP2 significantly correlated with the expression of ER. To understand the functional significance of IGFBP2 over expression in breast cancer, IGFBP2 was characterized with respect to proliferation, survival and tumor forming ability (in vitro and in vivo) in BT474 breast cancer cells. The knockdown of IGFBP2 expression resulted in suppression of colony formation (nearly 70%) in these breast cancer cells, which could be partially reversed upon exogenous addition of IGFBP2 protein. Proliferation assays using stable clones with knockdown of IGFBP2 in BT474 cells showed a significant decrease in proliferation as compared to vector transfected cells in the presence of serum. Culturing of IGFBP2 knockdown breast cancer cells in serum free medium resulted in their growth arrest in G0/G1 phase of cell cycle as compared to control cells, which progressed through the cell cycle. Prolonged culturing of IGFBP2 knockdown cells in serum free condition (up to 72 h) resulted in the increase of cells in sub G1 phase of the cell cycle. Prolonged depletion of growth factors (serum free conditions) could result in apoptosis of these G1 arrested IGFBP2 knockdown cells. When serum starved IGFBP2 knockdown cells were treated with IGFBP2 protein, the cells arrested in G0/G1 phase were able to progress through the cell cycle and concomitant decrease in sub G1 fraction was observed. Knockdown of IGFBP2 resulted in significantly decreased number and visibly smaller colonies in anchorage independent conditions in vitro. Consistent with this observation, in vivo tumor xenograft formation with IGFBP2 knockdown cells also showed significant reduction in tumor weight as compared to vector generated tumors. These results imply that IGFBP2 has potent growth promoting effects on breast cancer and acts as a mitogen/survival factor for breast cancer cells. To elucidate the molecular mechanisms underlying the pro-tumorigenic effects of IGFBP2, the transcriptome profile following IGFBP2 perturbation in breast cancer cells was determined. IGFBP2 knockdown resulted in significant changes in the expression of genes associated with cellular proliferation and tumorigenicity. The down regulated genes were found to be associated with several events, notably cell cycle, p53 and Wnt signaling, as revealed by Gene Set Enrichment Analysis (GSEA). To further validate these results in breast cancer tissues, whole genome expression analysis was performed in 19 breast tumor samples which were categorized as IGFBP2 positive or negative based on immunohistochemical staining pattern. In comparison to IGFBP2 negative tumors, IGFBP2 positive tumors showed increased expression of genes belonging to MAPK, focal adhesion and Wnt signaling pathway. In order to identify the genes commonly regulated by IGFBP2 in cell lines and tumors, the gene expression profiles of IGFBP2 positive versus IGFBP2 negative tumors and IGFBP2 knockdown breast cancer cells were compared. 347 genes were found to be common among IGFBP2 regulated genes in tumors and cell line. The most significant networks representing the web of interactions among these genes were found to be associated with cellular growth and proliferation, cellular movement and nucleic acid metabolism, indicating an association of IGFBP2 expression phenotype to the distinct changes in expression of genes associated with the regulation of cellular growth and migration. Silencing of IGFBP2 in BT474 cells resulted in a reduced IGF signaling as evidenced by the reduced phosphorylation of IGF1R and concomitantly that of ERK. This effect could be reversed upon addition of the IGFBP2 protein, implying that IGFBP2 potentiates IGF signaling in breast cancer cells. Besides IGF ligand and their receptors, regulation of proliferation associated genes like CENPF, TOP2A, CCND1 and FOXM1 by IGFBP2 was observed, thus providing a molecular basis for the pro-proliferative effects of IGFBP2 on breast cancer cells. Addition of IGFBP2 to immortal breast cells resulted in reduced IGF1R signaling and reduced pERK and pAKT signaling. Additionally, the genes involved in cellular proliferation were down regulated upon IGFBP2 treatment in immortal cells. IGFBP2 knockdown clones had reduced expression of FOXM1, a key regulator of cell cycle for G1/S and G2/M transition, and M phase progression. The regulation of CENPF and CCND1 genes was established following over expression of FOXM1 in IGFBP2 knockdown cells. One of the important and novel finding of this study is the regulation of Wnt signaling pathway genes such as CCND1, MMP7, FGF18, MYCBP, FN1 and survivin by IGFBP2. In support of this, β-catenin protein was found to be regulated by IGFBP2 in breast cancer and GBM cells, as evidenced by knockdown and over expression studies. Furthermore, regulation of β-catenin by IGFBP2 was found to involve integrin-FAK and IGF1R signaling. Another important finding of this study is the correlation of IGFBP2 over expression with elevated β-catenin levels in breast tumors. When expression of both IGFBP2 and β-catenin was correlated with the lymph node status of breast cancers, a significant association of IGFBP2 and β-catenin staining with increased lymph node metastasis was observed in comparison with tumors that did not show staining for either protein. Altogether, in this study employing genomic, cellular and molecular approaches, a pro- tumorigenic role for IGFBP2 in breast cancer has been established. Furthermore, this study provides novel insights into the molecular mechanisms employed by IGFBP2 involving IGF1R, FAK and Wnt signaling pathways during breast cancer progression.