The skin is the site where two of the most common types of epithelial cancer, basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), arise. In this work, we have investigated how ASPP2, a member of a family of proteins that interact with the p53 family, can affect skin tumourigenesis. ASPP2 is expressed in the squamous epithelia of various organs, localising exclusively in the upper and most differentiated layers. We show here that Balb/c ASPP2-null and heterozygous mice develop spontaneous SCCs. To investigate how the absence of ASPP2 from the epithelial compartment could lead to tumour formation, we analysed ASPP2’s relationship with pathways involved in the normal homeostasis of the epithelium, such as p63 and Notch. ΔNp63 is the main p63 isoform expressed in the adult epidermis, and its function is to drive the proliferation of the basal keratinocytes. Aberrant or misplaced activation of ΔNp63 in the epithelium is a known initiating cause for SCC. Consistent with this, ΔNp63 was found to be highly expressed in tumours derived from ASPP2-deficient mice. Our results indicate that ASPP2 is important in limiting ΔNp63 expression in the differentiated epithelium, preventing cell proliferation in the upper layers of the skin. This is achieved by antagonising ΔNp63 transcript and protein expression, resulting in a mutually exclusive expression pattern during differentiation of keratinocytes, as well as in epithelial cancer. ASPP2 expression was found reduced or lost in human SCC cell lines and during head and neck cancer progression, reflecting what was observed in ASPP2-deficient mice. Overall, our results indicate a possible mechanism by which p63 expression can be regulated in the skin, and provide a new model for the spontaneous formation of SCC in vivo. Additionally, we found that ASPP2 can cooperate with and enhance the activity of skin pro-differentiation pathways, such as Notch. In contrast to p63, ASPP2 and Notch1 are co-expressed in the differentiated layers of the squamous epithelium. Moreover, ASPP2 can interact with components of Notch nuclear transcriptional machinery, and it is shuttled into the nuclear compartment upon activation of Notch pathway. This recruitment results in modulation of Notch transcriptional activity on specific target genes with a differential pattern of binding sites, providing new insights into the understanding of Notch transcriptional regulation.

ABSTRACT In humans, advanced malignancies are often targeted with broad-spectrum cytotoxic drugs that engender several detrimental side effects, in addition to their primary usage for eradicating cancerous cells. One of the lesser-researched of these effects, histological distortion of the olfactory system impedes a patient's ability to smell, perceive flavor, and ultimately may interfere with their nutritional intake and recovery from chemotherapy. Recent studies have indicated that cytotoxic drugs can damage gustatory epithelia immediately following administration (Mukherjee & Delay, 2011, 2013). We sought to observe the histological effects that cyclophosphamide (CYP), one of the oldest and most popular alkylating antineoplastic agents, may have on the murine main olfactory epithelium (MOE) and vomeronasal organ (VNO). We utilized two immunohistochemical antibodies to label cells in the olfactory epithelia: anti-Ki67, a marker strictly associated with cell proliferation; and, anti-Keratin 5, a marker for the cytoskeleton of horizontal basal cells. Twenty-eight C57BL/6 mice were administered a single intraperitoneal injection of CYP (75 mg/kg), while 20 control mice were administered saline, all at approximately seven weeks of age. Mice were euthanized at days one, two, six, 14, 30, and 45 post injection; subsequently, they were perfused with 4% paraformaldehyde, decalcified, cryoprotected, cryosectioned, and incubated with anti-Ki67 and anti-Keratin 5 antibodies, sequentially. Quantification results by fluorescent imaging of labeled sections revealed a significant decrease in the number of proliferative cells in the MOE and VNO of CYP-injected mice within the first 10 days post injection, followed by a compensatory period of increased cell proliferation through day 45 post injection, compared to saline-injected mice. Co-localization of horizontal basal cells and proliferative cells in the MOE and VNO of CYP-injected mice was significantly amplified at approximately 14 and 45 days post injection, respectively, compared to saline-injected mice. Our results suggest that administration of CYP can rapidly depress the populations of proliferative cells in the murine MOE and VNO; consequently, horizontal basal cells may afford restoration of the proliferative cell populations in the murine MOE and VNO, 14 to 45 days post injection, respectively.

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal.

Des pathologies lourdes, telles que les dystrophies de la rétine et certains cancers, impliquent une désorganisation de l'épithélium et la famille Crb, dont la protéine apicale Crumbs3 (isoformes Crb3A et Crb3B) fait partie. Les protéines transmembranaires Crb possèdent un domaine intracellulaire fortement conservé et des partenaires communs. Il est donc essentiel de comprendre comment ces protéines Crb sont régulées afin de mieux appréhender ces pathologies. Pour cela, j'ai étudié le complexe de polarité apical Crb3A (Crb3A, Pals1, PATJ) impliqué dans l'établissement et le maintien de la polarité apico-basale. Je me suis, tout d'abord, intéressée à la régulation des isoformes de Crb3 par leurs partenaires (Pals1 et PATJ), puis, à la régulation des protéines de la membrane apicale, dont Crb3A, par la Drebrine E2, un nouveau partenaire de Crb3A impliqué dans l'organisation du cytosquelette d'actine et la morphogenèse apicale. Mon travail a permis de mettre en évidence: 1) la régulation de la dynamique membranaire des isoformes de Crb3 par PATJ dans les cellules Caco-2/TC7, une lignée épithéliale intestinale humaine, mais aussi, 2) d'identifier une nouvelle fonction de la Drebrine E2 dans la régulation du trafic de plusieurs protéines de la membrane apicale dans ces cellules, dont, par exemple, la DPPIV (DiPeptidyl Peptidase IV). Dans les cellules déplétées en Drebrine E2, l'expression des protéines apicales est diminuée et leur endocytose est augmentée, puis, elles sont relocalisées dans le compartiment majeur de dégradation, le lysosome. / Some serious diseases like retinal dystrophies and some cancers involve epithelial cells disorganization and the Crumbs (Crb) proteins family. The apical Crb3 (Crb3A and Cr3B isoforms) protein belongs to Crb family. The transmembrane proteins Crb have a conserved intracellular domain with common partners. It is unclear how Crb proteins are regulated by their partners and this information is required to better understand these pathologies. Here, we decided to study the apical polarity Crb3A complex (Crb3A, Pals1, PATJ) which is involved in apico-basal polarity establishment and maintenance. First, I investigated Crb3 isoforms regulation by their partners (Pals1 and PATJ). Then, I studied the regulation of apical membrane proteins, such as Crb3A, by Drebrin E2, a new partner of Crb3A which is involved in actin cytoskeleton remodeling and apical morphogenesis. During my thesis, I demonstrated: 1) the regulation of Crb3 isoforms dynamics by PATJ in Caco-2/TC7 human intestinal epithelial cells, but also, 2) a new function for Drebrin E2 in regulating the trafficking of apical membrane proteins, like DPPIV (DiPeptidyl Peptidase IV). In Drebrin E2 KD cells, apical membrane proteins expression is decreased and we observe an increased endocytosis. This leads to relocalization of the apical membrane proteins to the main degradative compartment, the lysosome. These new datas suggest a role for Drebrin E2 in the regulation of apical membrane proteins recycling pathway. The Drebrin E2 KD cells phenotype is reminiscent of the microvillar inclusions disease (MVID). Now, I am trying to investigate the link between theses pathways.

<p>The lungs are vital organs whose airways are lined with a continuous layer of epithelial cells. Epithelial cells in the distal most part of the lung, the alveolar space, are specialized to facilitate gas exchange. Proximal to the alveoli is the airway epithelium, which provides an essential barrier and is the first line of defense against inhaled toxicants, pollutants, and pathogens. Although the postnatal lung is a quiescent organ, it has an inherent ability to regenerate in response to injury. Proper balance between maintaining quiescence and undergoing repair is crucial, with imbalances in these processes leading to fibrosis or tumor development. Stem and progenitor cells are central to maintaining balance, given that they proliferate and renew both themselves and the various differentiated cells of the lung. However, the precise mechanisms regulating quiescence and repair in the lungs are largely unknown. In this dissertation, ionizing radiation is used as a physiologically relevant injury model to better understand the repair process of the airway epithelium. We use in vitro and in vivo mouse models to study the response of a secretory progenitor, the club cell, to various doses and qualities of ionizing radiation. Exposure to radiation found in space environments and in some types of radiotherapy caused clonal expansion of club cells specifically in the most distal branches of the airway epithelium, indicating that the progenitors residing in the terminal bronchioles are radiosensitive. This clonal expansion is due to an increase in p53-dependent apoptosis, senescence, and mitotic defects. Through the course of this work, we discovered that p53 is not only involved in radiation response, but is also a novel regulator of airway epithelial homeostasis. p53 acts in a gene dose-dependent manner to regulate the composition of airway epithelium by maintaining quiescence and regulating differentiation of club progenitor cells in the steady-state lung. The work presented in this dissertation represents an advance in our understanding of the molecular mechanisms underlying maintenance of airway epithelial progenitor cells as well as their repair following ionizing radiation exposure.</p> / Dissertation

The plot of this PhD thesis is dedicated to investigation of the molecular pathways and events and their disruptions in the gastrointestinal tract (further abbreviated as GIT). The major role in this part plays the Wnt signaling pathway. This marvelous multipurpose machinery is responsible for epithelia renewal from stem cells (SCs) in the stomach and intestine, and for correct zonation and function of hepatic units. Of note, the Wnt pathway directs also development of embryo as well as homeostasis of many tissues apart from GIT in all metazoans, thus its flawless function is indispensable from one's origin to death. The main part of the thesis follows canonical Wnt signaling in its physiological condition and, in contrast, with pathological disturbances. This issue can be taken by variety of means as it is described in attached publications. The first publication deals with searching for new participants of Wnt signaling and their functions and describing unique markers of SCs in the intestine. Troy, the member of tumor necrosis factor receptor (TNFR) superfamily, was identified as a novel marker of intestinal SCs by probing microarray data from chromatin immunoprecipitation obtained in cultured colorectal cancer cell lines. Moreover, we found that Troy is a Wnt target gene inhibiting the...

La Broncho-pneumopathie Chronique Obstructive (BPCO) est une maladie respiratoire grave caractérisée par une inflammation chronique entrainant des lésions irréversibles de l’épithélium respiratoire et du parenchyme pulmonaire. Le principal facteur de risque est le tabagisme mais des études d’association génétique pangénomiques ont montré que certains polymorphismes nucléotidiques simples (SNP) des récepteurs nicotiniques (nAChRs) sont associés à l’incidence de la BPCO. Un de ces polymorphisme est le variant rs16969968 dans le 5ème exon du gène CHRNA5 codant la sous-unité α5. Le but de ce travail a été d’évaluer in vivo l’implication du SNP α5 dans les lésions pulmonaires caractérisant la BPCO et d’étudier l’impact fonctionnel du polymorphisme sur les voies de signalisation mises en jeu en aval des nAChRs. A l’aide de différents modèles in vivo murins et humains, nous avons pu montrer qu’indépendamment du tabagisme, le SNPα5 est associé à une inflammation cellulaire plus marquée, une sécrétion de cytokines pro-inflammatoires, des lésions emphysémateuses, une hyperplasie des cellules mucipares et des cellules Club moins fréquentes par rapport au génotype sauvage. Le SNPα5 est associé à une altération de la perméabilité calcique des cellules épithéliales et une modulation de la voie de signalisation AC3-PKA/C. Cette étude apporte pour la première fois une explication biologique à l’association entre le SNPα5 et la BPCO décrite dans les études d’association génétique pangénomiques à travers un rôle pro-inflammatoire du SNPα5 au niveau pulmonaire. / Chronic Obstructive Pulmonary Disease (COPD) is a critical respiratory disease characterized by a chronic inflammation leading to irreversible epithelial and parenchymal injuries. The main risk factor is tobacco consumption but several genome-wide association studies (GWAS) described some single-associated polymorphisms (SNP) on nicotinic acetylcholine receptors (nACHR) genes associated with COPD incidence. One of these polymorphisms is the rs16969968 variant in the 5th exon of CHRNA5 gene coding the α5 subunit (SNP α5). The aim of this study was to determine in vivo the involvement of SNPα5 in COPD-associated lung injuries and to deciphere the functional impact of the polymorphism on nAChR signaling pathways. Thanks to several in vivo models (mouse and human), we describe here that the SNPα5 is associated, irrespective of the tobacco consumption, to an increased inflammation, pro-inflammatory cytokines secretion, emphysema, goblet cell hyperplasia, and Club cell diminution compared to the wild-type genotype. The SNPα5 is associated with a decreased calcium influx and a modulation of AC3-PKA/C pathway in airway epithelial cells. Our study describe for the first time a biological explanation for the association between SNPα5 and COPD shown in GWAS with a pro-inflammatory role of SNPα5 in the lung.

Este trabalho teve como objetivo propor novo método para estudar a permeabilidade de fármacos, utilizando epitélio intestinal de rã-touro (Rana catesbeiana) em método ex vivo, empregando células de Franz. Por utilizar epitélio intestinal, um material de descarte proveniente de um animal utilizado como alimento humano, pode ser considerado um método alternativo, pois não implica no sacrifício de animais. A quantidade de fármaco permeada foi determinada por método de eletroforese capilar com detecção ultravioleta e validado para os antivirais lamivudina, zidovudina e aciclovir, na presença de metoprolol e floridizina. O fármaco escolhido como modelo nos ensaios de permeabilidade foi a lamivudina. Para estabelecimento do protocolo experimental dos estudos de permeabilidade, foi proposta uma análise de variância three-way para verificar a influência na permeabilidade dos fármacos, das seguintes variáveis: secção intestinal, pH da solução de Ringer e temperatura. Foram determinados a quantidade total de fármaco permeado (Qt), o coeficiente de permeabilidade aparente (Papp) e a constante de absorção de primeira ordem (ka). A partir da análise do planejamento experimental, os efeitos das variáveis não foram significativos, exceto para a secção intestinal. Os resultados de coeficiente de permeabilidade aparente (Papp) obtidos foram de 0,09 x 10-4 cm/s para lamivudina e de 0,22 x 10-4 cm/s para o metoprolol. O valor de Papp obtido de para o metoprolol é próximo dos valores encontrados na literatura para outras técnicas. Para a lamivudina, entretanto, a diferença encontrada em comparação às células Caco-2 pode ser devida às diferentes técnicas empregadas. / This work aimed to propose a new method for studying drug permeability using frog intestinal epithelium (Rana catesbeiana) in ex vivo method, using Franz cells. By using intestinal epithelium, a disposal material from an animal used as human food, can be considered an alternative method, because it doesn\'t involve the sacrifice of animals. The amount of permeated drug was determined by capillary electrophoresis method with UV detection and validated for antiviral drugs lamivudine, zidovudine and acyclovir in the presence of metoprolol and floridizina. The drug chosen as a model in permeability studies was lamivudine. To establish the experimental protocol for the permeability studies, a three-way analysis of variance was proposed to check the influence of intestinal section, pH of Ringer\'s solution and the temperature on the permeability. Total amount of drug permeated (Qt), apparent permeability coefficient (Papp) and first-order constant absorption (ka) were determined. By the analysis of experimental design, the effects of the variables were not significant, except for intestinal section. The results of apparent permeability coefficient (Papp) obtained were 0.09 x 10-4 cm/s for lamivudine and 0.22 x 10-4 cm/s for metoprolol. The value of Papp obtained for metoprolol is quite close to the values found in literature for other methods. For lamivudine, however, the difference found in comparison to Caco-2 cells may be due to different techniques.

Antiinflamatórios não-esteroidais (AINEs) são muito utilizados para o alívio da dor. Estudos indicam que 1 em 7 pacientes com doenças inflamatórias crônicas usam AINEs e que 1 em 5 pessoas usam AINEs para dores agudas. Os AINEs inibem a cicloxigenase (COX-1 e COX-2) ou seletivamente a COX-2, e apesar de sua excelente ação antiinflamatória e analgésica, muitos são os efeitos colaterais. Problemas gastrointestinais (GI) são a queixa mais comum para os AINEs convencionais, que também são associados a apoptose de diferentes tipos celulares. Os COX-2 seletivos apresentam menos problemas GI, mas seu uso tem sido questionado pelo risco de trombose e enfarto do miocárdio. Todos os AINEs parecem interferir no processo de cicatrização, embora os resultados dos estudos realizados apresentem-se conflitantes. Uma vez que os AINEs são utilizados por grande número de pessoas, o objetivo do nosso trabalho foi avaliar os efeitos dessa medicação sobre o tecido epitelial e durante o processo de cicatrização. Ratos Wistar foram tratados diariamente com AINEs convencional (diclofenaco, 3mg/Kg) ou um COX-2 seletivo (Celecoxibe, 1mg/Kg) por períodos de 7 e 14 dias. O controle foi feito com animais da mesma idade e peso não submetidos ao tratamento com AINEs. Após 7 dias, em todos os animais, controles e tratados, foram realizadas feridas cirúrgicas (4cm de diâmetro) no dorso depilado, sob anestesia com Tribromoetanol. Foram analisados, histológica e histometricamente, os epitélios da mucosa bucal, e a área de cicatrização (3 e 7 dias pós-cirurgia). Os resultados obtidos foram tabelados para avaliação estatística apropriada. No geral foi possível observar que todos os AINEs provocaram alterações com o seu uso agudo, no entanto para os inibidores seletivos da COX- 2 houve uma tendência à normalização com o uso crônico, não observada com o uso do AINE convencional. Na avaliação da cicatrização foi possível observar que os AINEs convencionais provocaram um pequeno atraso no processo de cicatrização, o que não foi observado com o uso de AINE seletivo para COX-2. Foi possível concluir que é necessário cautela em pacientes que fazem uso de AINEs, por provocarem alterações significativas no epitélio bucal, sendo os convencionais os que apresentam alterações mais significativas principalmente a longo prazo / Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used for pain relief mostly in inflammatory chronic diseases. One in 7 patients with chronic inflammatory diseases uses NSAIDs, 1 in 5 uses NSAIDs for acute pain. NSAIDs may inhibit cyclooxygenase (COX-1 and COX-2) or COX-2 selectively, and despite their excellent anti-inflammatory and analgesic action, there are many side effects related. Gastrointestinal (GI) problems are the most commmon complaint for conventional NSAIDs, wich are also associated with different cell types apoptosis. The COX-2 selective NSAIDs have less GI problems, but may be associated to risks of cardiovascular events. All of NSAIDs seems to interfere with wound healing, although studies results may show conflicting results. Since NSAIDs are used by large numbers of people, the aim of this study was to evaluate the effects of this medication on the epithelial tissue and during wound healing process. Wistar rats were treated daily with conventional NSAIDs (diclofenac, 3mg/Kg) or selective COX-2 (celecoxib, 1mg/Kg) for a period of 7-14 days. The control group was animals of similar age and weight not treated with NSAIDs. After 7 days in all the animals, control and treated, were made surgical wounds (4cm in diameter) on the shaved back under anesthesia with Tribromoethanol. Oral mucosa and wound healing were histological and histometrically analyzed (3 and 7 days after surgery). The results received appropriated statistical evaluation. It was possible to observe that both NSAIDs lead to changes with acute use, but only selective COX-2 inhibitors tends to get back to normal parameters with long lasting use. Related to wound healing, it was possible to verify that conventional NSAIDs was associated to a slightly delay in wound healing process, which was not observed with selective COX-2 NSAIDs use. It was possible to conclude that caution is needed with the use of NSAIDs. They cause significant changes in oral epithelium and the convenional one causes most signifcant changes with long term use

O chá verde e um produto da planta Camellia sinensis e apresenta em sua composição mais de 200 substâncias, sendo as mais conhecidas as catequinas, ou polifenóis, ou flavonóides, mas há também os polissacarídeos conjugados, os aminoácidos, cafeína e vitaminas. Estudos têm demonstrado que o consumo regular de chá verde reduz o risco de câncer, protegendo contra seus eventos iniciais e retardando a progressão da doença, que possui ação antioxidante e propriedades bactericidas e pode ser um coadjuvante no tratamento de diabetes, hipertensão e hipercolesterolemia. O objetivo desse trabalho foi avaliar e comparar as características dos epitélios de revestimento da pele e da mucosa bucal, assim como o processo de cicatrização, em animais controle e os que fizeram uso de chá verde. Ratos Wistar receberam chá verde para beber no lugar de água. O controle foi realizado com animais com pesos e idades semelhantes que receberam água de torneira para beber. Após 2 semanas, controles e tratados foram submetidos à cirurgia em seu dorso, sendo essas áreas avaliadas aos 1, 3 e 7 dias de pós-operatório (PO). Para avaliação dos epitélios sem cirurgia foram utilizados animais tratados com chá verde durante 2 e 8 semanas e foram utilizados os epitélios da pele, da língua, dos palatos mole e duro e da gengiva. Na avaliação da cicatrização, observou-se aumento de epitélio neoformado aos 3 dias PO, e diminuição de edema tanto aos 3, quantos aos 7 dias PO. Observaram-se, na avaliação dos epitélios, alterações nucleares e epiteliais nos períodos iniciais de uso do chá verde, que tendem a ser normalizadas com o uso continuado; foram avaliados, também, os valores de colesterol total, triglicérides, HDL, VLDL e LDL e observou-se diminuição significativa principalmente nos valores de triglicérides. / Green tea, a product from Camellia sinensis, consists of over 200 components. The most known are the catechins, or polyphenolic compounds, or flavonoids, but it contains also polysacharide conjugates, amino acids, caffeine and vitamins. Studies have suggested that the regular use of green tea reduces the risk of cancer, protecting against initial events and progression of the disease, that may act as antioxidant, has bactericidal properties, and that green tea consumption may be an adjuvant in the treatment of diabetes mellitus, hypertension and hypercholesterolemia. The purpose of this study was the evaluation the oral epithelium, skin epithelium and wound healing process. Our experimental study was carried out with Male Wistar rats, separated in two groups, experimental and control. To the control group were served water ad libitum, and the experimental group received green tea instead of water. After 2 weeks of experimental period, all the animals, control and experimental groups, suffered surgical wounds on the dorsum. The animals were sacrificed on days 1, 3 and 7 after surgery. Skin samples were used for light microscopy evaluation. Our results allow us to observe that the experimental group (green tea drinking) presented accelerated epithelial neoformation on day 3 after surgery, when epithelial neoformation is in initial phases. To epithelium evaluation were used animals receiving green tea for 2 and 8 weeks (skin, tongue, palates and gun were used). We observed epithelial and nuclear changes, but this values tend of return to control patterns with continued use. We also evaluated lipoproteins, such as total cholesterol, triglycerides, HDL, LDL and VLDL. Triglycerides values were significantly decrease in experimental group.