Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O câncer colo-retal (CCR) representa o quarto tipo de câncer mais freqüente no Brasil entre homens e mulheres e a sobrevida para esse tipo de neoplasia é considerada boa, se a doença for diagnosticada em estádio inicial. Neste tipo de câncer a progressão do adenoma (tumor benigno) para o adenocarcinoma (tumor maligno) é dependente do acúmulo de mutações em diversos oncogenes e genes supressores de tumor. Estas mutações podem levar a alterações de importantes vias de sinalização que controlam estes eventos como, por exemplo, as vias Wnt e EGFR. No entanto, os mecanismos moleculares e celulares mediados por estas vias durante a progressão do CCR permanecem por serem definidos. Neste trabalho foi avaliada a participação da via Wnt e do EGFR durante a progressão do CCR usando células Caco-2, uma linhagem celular derivada de adenocarcinoma de cólon humano como modelo. As células foram tratadas com EGF, ativador da via EGFR, e cloreto de lítio (LiCl), um conhecido inibidor da enzima GSK-3β e conseqüentemente, ativador da via Wnt, ou alternativamente com a combinação de ambas drogas. Após os tratamentos, foi avaliada a morfologia celular, localização e expressão de proteínas juncionais, os padrões proliferativos e do ciclo celular e o potencial tumorigênico (migração e formação de colônias). Nossos resultados mostram que a localização subcelular das proteínas juncionais claudina-1 e β-catenina foi alterada após tratamento com EGF e LiCl, porém a expressão não foi afetada. A localização nuclear de β-catenina, um marcador da ativação da via Wnt, foi observada após tratamento com ambos os compostos, no entanto estes agentes modularam a enzima GSK-3β de forma diferencial. Além disso, tratamento com EGF aumentou a capacidade proliferativa e migratória da célula, mas não alterou a formação de colônias. LiCl, apesar de ser um conhecido ativador da via Wnt, inibiu o aumento da proliferação e migração causado pelo EGF, como visto pelo tratamento das células com EGF+LiCl, e reduziu a formação de colônias. Nossos resultados revelaram que LiCl possui uma atividade supressora de tumor o que pode representar um novo papel para este composto como um possível agente terapêutico para o tratamento do CCR. / Colorectal cancer (CCR) represents the fourth type of cancer most common in Brazil among men and women and the survival for this tumor type is considered good if the disease is diagnosed at early stage. The progression of an adenoma (benign tumor) to an adenocarcinoma (malign tumor) is dependent on the accumulation of mutations in a variety of oncogenes and tumors suppressors genes. These mutations can lead to alterations of important cell signaling pathways that control these events, such as Wnt e EGFR. However, the molecular and cellular mechanisms mediated by these pathways during CCR progression remain to be defined. In the present study we assesses the role that Wnt and EGFR pathway play during CCR progression using Caco-2 cells, a human cell line derived of colorectal cancer, as a model. Cells were treated with EGF, an EGFR pathway activator, and lithium chloride, (LiCl) a known inhibitor of the enzyme GSK-3β and, therefore a Wnt pathway activator or alternatively by using combination of both drugs. After treatments, we monitored cell morphology, localization and expression of junctional proteins, proliferative and cell cycle patterns, and the tumorigenic potential (cell migration and colony formation). We show that subcellular localization of the junctional proteins claudin-1 and β-catenin was altered after treatment with EGF and LiCl, however the expression were not affected. Nuclear localization of β-catenin, a marker of Wnt pathway activation, was observed after treatment with both compounds, however these agents modulated in a differential fashion the enzyme GSK-3β. Furthermore, EGF treatment increased the proliferative and migratory capacity of the cells, but did not alter colony formation potential. LiCl, despite being a known activator of the Wnt pathway, inhibited the increase of proliferation and migration caused by EGF, as demonstrated by the cell treatments with EGF+LiCl, and reduced the cell colony formation. Our results reveal that LiCl present a suppressor tumor activity, which may represent a new role for this compound as potential therapeutic agent in the CCR treatment.

O câncer de mama é a neoplasia responsável pelo maior número de mortes em mulheres no Brasil, portanto, é importante encontrar novos marcadores específicos e de diagnóstico precoce, utilizando procedimentos simples e rápidos. A via de sinalização Wnt regula importantes funções celulares como proliferação, sobrevida e adesão. Esta via está associada com os processos de iniciação e progressão em muitos tipos tumorais, como câncer de cólon familiar, melanoma e pulmão; sendo que mutações em β-Catenina (CTNNb1) explicam só 30% dos casos de sinalização aberrante encontrada no câncer de mama, indicando que existem outros componentes e/ou reguladores da via que possam estar envolvidos. O objetivo deste trabalho foi avaliar as variantes genéticas e epigenéticas nos genes do complexo de degradação de β-Catenina num grupo de pacientes com câncer de mama e num grupo controle; e determinar os perfis de transcrição dos componentes da via de sinalização Wnt e da molécula de expressão exclusiva do epitélio mamário, a Mamaglobina Humana (MGA), assim como associar estes resultados com as características clínicas, histológicas e patológicas do tumor. Para atingir este objetivo foram coletadas amostras de sangue periférico de 102 mulheres com câncer de mama e 102 mulheres sadias como grupo controle. A avaliação das variantes rs465899 do gene APC, rs2240308 e rs151279728 do gene AXIN2, rs5030625 do gene CDH1 e rs334558 do gene GSK3, foi realizada por meio de PCR-RFLPs e sequenciamento, a análise dos perfis de metilação dos promotores pela MS-PCR. A RT-qPCR foi usada para determinar os níveis de expressão dos componentes da via e a MGA. As variantes rs2240308 e rs151279728 do gene AXIN2 mostraram uma forte associação com o risco de desenvolver o câncer de mama. Um aumento significativo foi observado no nível de expressão de AXIN2 no grupo de mulheres com câncer de mama. Análises adicionais mostraram perfis de expressão diferencial dos genes APC, AXIN2, CTNNB1, GSK3 e CSNK1A1 associado ao status dos receptores hormonais e histogênese tumoral. MGA foi identificado exclusivamente em 38% dos pacientes com câncer de mama e foi associada com a progressão da doença. Este é o primeiro estudo que relaciona uma variante do gene AXIN2 com o câncer de mama na população brasileira. As variantes avaliadas do gene AXIN2 são marcadores promissores de susceptibilidade ao câncer de mama na população estudada, sendo importante, a avaliação desta variante genética na população e determinar o seu real efeito no processo de iniciação e/ou progressão do câncer de mama. / Background: Wnt/β-catenin signaling pathway is an important regulator of cellular functions such as proliferation, survival and cell adhesion. This pathway is associated with tumor initiation and progression; -catenin (CTNNB1) mutations explains only 30% of aberrant signaling found in breast cancer, indicating that other components and/or regulating of the Wnt/β-catenin pathway may be involved. Objective: The objective of the study was to evaluate the APC rs465899, AXIN2 rs2240308 and rs151279728, CDH1 rs5030625 and GSK3 rs334558 polymorphisms, APC, AXIN2, CDH1 and GSK3 promoter methylation status and expression profile of -Catenin destruction complex genes and MGA in peripheral blood of breast cancer patients. Methods: We collected peripheral blood samples from 102 breast cancer and 102 healthy subjects. The identification of the mutation was performed using PCR-RFLPs and DNA sequencing. MSP and HRM-MS was used to measure promoter methylation and RT-qPCR to determine expression profile. Results: We found significant association of AXIN2 rs2240308 polymorphism with breast cancer. Increased risk was observed even after stratification based on clinicpathological characteristics. AXIN2 rs151279728 polymorphism was found only in 9 breast cancer patients, but none in control group subject. APC and CDH1 polymorphisms were not associated with breast cancer. GSK3 polymorphism was weak associated with breast cancer and heterozygous status was associated with breast cancer protection after group stratification. APC and CDH1 promoter methylation in breast cancer patients was found. Significant increase was observed in AXIN2, CTNNB1 and GSK3 level expression in breast cancer patients. APC was down-regulated in breast cancer patients. Further analyses, showed APC, AXIN2, CTNNB1, GSK3 and CSKN1A1 gene expression associated to receptor status and histological type. MGA was found only in breast cancer patients and was associated with cancer progression. Conclusion: The present study reports, for the first time, that AXIN2 genetic defect and -catenin destruction complex expression disturbance may be found in breast cancer patients, providing additional support to the role of Wnt/-catenin pathway dysfunction in breast cancer tumorigenesis. However, the functional consequence of this genetic alteration remains to be determined. In another hand MGA was determined like a good biomarker for diagnosis and prognosis outcome.

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.

Οι φυλλοειδείς όγκοι του μαστού είναι σπάνια διφασικά νεοπλάσματα, με ποικίλου βαθμό κίνδυνο για τοπική υποτροπή και μετάσταση, που αποτελούνται από επιθηλιακό και στρωματικό στοιχείο. Η επιθηλιακή προς μεσεγχυματική μετατροπή, κρίσιμης σημασίας γεγονός κατά την εμβρυογένεση, έχει φανεί ότι συμμετέχει στην παθογένεια της ίνωσης διαφόρων οργάνων καθώς και στη διηθητική και μεταστατική ικανότητα πολλών τύπων καρκινωμάτων. Ο σκοπός της παρούσας μελέτης είναι η διερεύνηση του κατά πόσον το φαινόμενο ΕΜΤ συμμετέχει στην παθογένεια των φυλλοειδών όγκων. Υλικό-Μέθοδος: Η έφραση της Ε-καντχερίνης, της β-κατενίνης και της ILK μελετήθηκε ανοσοϊστοχημικά σε δείγματα μονιμοποιημένα σε φορμόλη και εγκλεισμένα σε παραφίνη από 71 εξαιρεθέντες φυλλοειδείς όγκους, 44 καλοήθεις (62%), 20 ενδιάμεσης κακοήθειας (28%) και 7 κακοήθεις (10%). Διερευνήθηκαν συσχετίσεις με κλινικοπαθολογικές παραμέτρους όπως τον ιστολογικό τύπο των όγκων (καλοήθεις, οριακής κακοήθειας και κακοήθεις). Αποτελέσματα: Στο μη νεοπλασματικό επιθήλιο παρατηρήθηκε μεμβρανικής εντόπισης ανοσοθετικότητα για την Ε-καντχερίνη και τη β-κατενίνη και αρνητική ανοσοχρώση για την ILK. Αντίθετα, στο επιθηλιακό στοιχείο των όγκων παρατηρήθηκε μείωση της μεμβρανικής εντόπισης ανοσοθετικότητας για την Ε-καντχερίνη και τη β-κατενίνη. Η απώλεια της μεμβρανικής Ε-καντχερίνης ήταν μεγαλύτερη στους οριακής κακοήθειας και κακοήθεις όγκους (Kruskal-Wallis test p=0.000). Πυρηνικής και κυτταροπλασματικής εντόπισης ανοσοθετικότητα για την Ε-καντχερίνη και τη β-κατενίνη, καθώς και πυρηνικής και κυτταροπλασματικής εντόπισης ανοσοθετικότητα για την ILK ανιχνεύθηκαν τόσο στο επιθηλιακό όσο και στο στρωματικό στοιχείο των όγκων. Στους οριακής κακοήθειας και κακοήθεις όγκους παρατηρήσαμε στατιστικώς σημαντικά μεγαλύτερη πυρηνική/κυτταροπλασματική ανοσοθετικότητα Ε-καντχερίνης ( Kruskal-Wallis test p=0.013/p=0.006 αντίστοιχα για επιθηλιακά κύτταρα και p=0.017 για στρωματικά κύτταρα) και μεγαλύτερη πυρηνική/κυτταροπλασματική ανοσοθετικότητα για την ILK (Kruskal-Wallis test p=0.031 /p=0.012 αντίστοιχα για στρωματικά κύτταρα). Συμπέρασμα: Τα ευρήματα αυτά υποδηλώνουν ότι μία διεργασία τύπου ΕΜΤ μπορεί να εμπλέκεται στην παθογένεια των φυλλοειδών όγκων συμβάλλοντας στην δημιουργία όγκων με πιο επιθετικό φαινότυπo. / Phyllodes breast tumors consist of epithelial and mesenchymal components. Epithelial-mesenchymal transition (EMT) has been implicated in carcinogenesis. The aim of this study was to investigate whether EMT is involved in the pathogenesis of phyllodes breast tumors. Methods: E-cadherin, β-catenin and integrin-linked kinase (ILK) expression was evaluated immunohistochemically in 71 FFPE human phyllodes breast tumors (44/71 (62%) benign, 20/71 (28%) bordeline and 7/71 (10%) malignant). Correlations with tumor histopathology (benign, borderline, malignant) were investigated. Results: Non-neoplastic breast epithelium showed membranous E-cadherin and β-catenin expression and negative ILK immunoreactivity. Decreased membranous expression of E-cadherin and β-catenin in tumor epithelial component was observed. Loss of membranous E-cadherin was higher in borderline/malignant tumors (Kruskal-Wallis test p=0.000). Nuclear/cytoplasmic immunoreactivity of E-cadherin and β-catenin, as well as nuclear/cytoplasmic expression of ILK was detected in both epithelial and stromal tumor cells. We observed significantly higher nuclear/cytoplasmic immunoreactivity of E-cadherin (Kruskal-Wallis test p=0.013/p=0.006 respectively for epithelial cells and p=0.017 for stromal cells) and nuclear/cytoplasmic stromal expression of ILK (Kruskal-Wallis test p=0.031 /p=0.012 respectively) in borderline/malignant tumors. Conclusion: These results suggest that an-EMT-like process may be implicated in phyllodes breast tumors pathogenesis contributing to a more malignant phenotype.

One major reason of CNS pharmacotherapy's impediment is the existence of "barriers" between blood and CNS, especially the Blood-Brain Barrier (BBB), a neurovascular structure localized at the level of brain microvasculature. Main factors responsible for this barrier function are drug efflux transporters type ABC (ATP-Binding Cassette) and SLC (SoLute Carrier) expressed at BBB level and known to be at the origin of multi-drug resistance phenomenon. Recent researches aim at unraveling the signaling mechanisms regulating these transporters in order to modulate their activity and improve pharmacotherapy in brain diseases. For years, these transporters have been studied in adult organism. But, there is a wide spread belief that the BBB in embryo, fetus, new born and infant is "immature", implying caution in giving drugs to infants. However, current knowledge on the functional status of the BBB in immature organism remains very limited.This study was performed in the aim of understanding: 1) The ontogenesis of ABC and SLC transporters during brain maturation, 2) the functional role of four BBB drug efflux transporters (P-glycoprotein (P-gp), Breast Cancer Resistance Protein (bcrp), Organic Anion Transporter 3 (oat3), and Transporting Peptide 1a4 (oatp1a4) transporters) in children's brain, and 3) the mechanisms that regulate their functional expression under normal and pathological conditions, mostly under inflammatory conditions, because indeed alterations in structural and functional components of the BBB have been reported in a long list of CNS pathologies in adults. Our results showed changing properties of the BBB during ontogenesis, as well as an age-related differential regulation of BBB drug efflux transporters under normal and inflammatory conditions.These findings highlight the importance of considering an age-related response of CNS to drugs and of taking into account the specific properties of juvenile BBB during definition of therapeutic strategies designed to treat childhood brain diseases, and this in the clinical perspective of developing new drugs with enhanced efficacy in children's CNS.

Insulin like Growth Factor Binding Proteins (IGFBPs) 1 to 6 have important physiological functions of regulating half life and bioavailability of Insulin like Growth Factors (IGFs). Consequently, these have been known to play important roles in embryonic development, postnatal growth and disease conditions like cancer. However, the physiological roles of IGFBPs are diverse and not restricted only to the IGF regulation. These molecules are found to be tumor suppressors or promoters depending on the physiological contexts. IGFBP-2 has been established as a tumor promoter and found to be unregulated in several cancers including breast, ovarian, prostate cancer and glioblastoma (GBM). Various in vitro and in vivo studies have convincingly demonstrated the role of IGFBP-2 in inducing tumor cell proliferation, migration, invasion and chemoresistance. Increased plasma and tissue levels of IGFBP-2 have been associated with poor clinical outcome with respect to patients’ response to the therapy, relapse and overall survival. Various studies so far have demonstrated the role of IGFBP-2 in promoting glioma cell proliferation, migration, invasion, chemoresistance and determining stamens of GICs (Glioma Initiating Cells). However, the exact mechanisms underlying these functions remain unknown. Apart from being a diagnostic and prognostic indicator, IGFBP-2 has also been proposed as a therapeutic target. Therefore it is essential to understand mechanistic insights into pro-tumorigenic functions of IGFBP-2. Apart from the conventional function of regulating IGFs, IGFBP-2 has been shown to have several IGF independent functions. In a previous study, we reported IGFBP-2 as an upstream regulator of β-catenin signaling pathway in breast cancer. Interestingly, this study linked the association of higher expression of IGFBP-2 and β-catenin with the lymph node metastasis status of breast cancer. β-catenin signaling has been considered as one of the most important pro-tumorigenic pathways in several cancers including glioblastoma. Considering the importance of IGFBP-2 and β-catenin signaling pathways in glioblastoma, it becomes important to evaluate regulation of β-catenin activity by IGFBP-2 in glioma and address its clinical relevance. With this aim, the objectives of this study are,  To study mechanism of IGFBP-2 mediated regulation of β-catenin signaling in glioma cells and prognostic significance of IGFBP-2 and β-catenin expression in GBM tissues.  Isolation of human single chain variable fragment (scFv) against IGFBP-2 and its characterization as an inhibitor for IGFBP-2 pro-tumorigenic functions. Towards this, we established stable IGFBP-2 knockdown U251 cell line and IGFBP-2 over expressing LN229 and U87 cell lines. IGFBP-2 modulation in these glioma cell lines did not alter the rate of proliferation but there was a significant effect on cellular migration and invasion. In case of U251 cell line, there was a significant decrease in the intracellular levels of β-catenin while in IGFBP-2 over expressing cell lines there was a marked increase in intracellular β-catenin suggesting that IGFBP-2 is involved in the regulation of β-catenin in these cells. It was observed that this regulation of β-catenin was not because of its transcriptional regulation or regulation of canonical Wnt ligands Wnt1, Wnt2 and Wnt3a. To further delineate the pathway and understand the mechanism behind regulation of β-catenin, upstream regulators of β-catenin were analyzed. GSK3β is an important negative regulator of β-catenin which primes it for ubiquitination and proteasomal degradation. Phosphorylation of GSK3β at Ser9 position renders this enzyme inactive. In our study, it was observed that there was a significant downregulation of p-GSK3β in U251 cells with IGFBP-2 knockdown and upregulation in IGFBP-2 over expressing cell lines. Overexpression of IGFBP-2 in LN229 and U87 cell lines resulted in considerable decrease in the GSK3β mediated phosphorylation of β-catenin. This study unequivocally established that regulation of β-catenin by IGFBP-2 is via inactivation of GSK3β. Furthermore, regulation of GSK3β was found to be due to action of FAK following binding of IGFBP-2 to integrins. The expression pattern of IGFBP-2 and β-catenin protein in the tumor tissues of 112 GBM patients was studied and its correlation with patient survival was analysed. In this analysis it was observed that co-expression of IGFBP-2 and β-catenin is a strong predictor of patient prognosis. These results further implied the importance of understanding IGFBP-2 and β-catenin association in GBM pathology. One of the interesting observations in our study is that, not only full length IGFBP-2 protein but also C-terminal domain of IGFBP-2 was sufficient to regulate β-catenin and other IGFBP-2 mediated functions. This strongly asserts the importance of C-terminal region of IGFBP-2 as a tumor promoter. Towards an attempt to develop an inhibitor for IGFBP-2 actions, we screened a human single chain variable fragment (scFv) library using phage display technique. From this screening, one scFv (B7J) was identified which was a binder of full length IGFBP-2 as well as C-terminal domain of IGFBP-2. This scFv showed inhibition of IGFBP-2-cell surface interaction and also efficiently inhibited IGFBP-2-induced signaling pathways like ERK, FAK and GSK3β/β-catenin. B7J treatment also neutralized regulation of IGFBP-2 transcriptional targets like MMP2 and CD24. Gelatin zymography indicated the ability of B7J to decrease matrix metalloprotease activity in the conditioned medium of glioma cells. These effects ultimately reflected on the IGFBP-2-induced cellular migratory and invasive behaviour which was largely abrogated by B7J scFv treatment. Considering the therapeutic importance of scFvs because of their small size, better tumor penetration and tumor retention capacity than full length antibody molecules, such kind of strategy could be of great importance in the management of GBM. Altogether, this study provides a mechanistic insight of IGFBP-2 mediated actions involving integrin/FAK/GSK3β/β-catenin pathways and the possible role of this crosstalk in the aggressiveness of glioblastoma. This study also provides a proof of principle that an inhibitor like anti IGFBP-2 scFv could be of importance for controlling invasive glioblastoma.

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