Les canaux anioniques ont toujours été sous-estimés par rapport aux canaux cationiques principalement en raison des difficultés à caractériser leurs identités moléculaires et par l'absence d'inhibiteurs sélectifs puissants. C’est une classe comportant une grande hétérogénéité et une importante complexité comprenant entre autres le CFTR activé par l’AMP cyclique, les anoctamines activées par le calcium intracellulaire et les canaux VRAC activés lors d’un gonflement cellulaire. L’identité moléculaire d’une protéine essentielle aux courants ioniques déclenchés par le gonflement cellulaire a été découverte en 2014, permettant de pouvoir enfin investiguer le fonctionnement et le rôle de ces canaux. Dans une première partie, nous avons démontré l’absence de spécificité des inhibiteurs des principaux canaux chlorures. Cette étude met en exergue le besoin de développer de nouveaux inhibiteurs permettant de discriminer les différents canaux chlorures, mais aussi la nécessité de coupler l’approche pharmacologique à une approche génétique. Dans une deuxième partie, nous avons mis en évidence la perméabilité des canaux anioniques sensibles au gonflement cellulaire au glutathion, principal antioxydant cellulaire. Nos résultats suggèrent donc que les canaux VRAC pourraient être impliqués dans la régulation du stress oxydatif. Dans la troisième partie de ma thèse, nous avons montré que le facteur de croissance TGFβ1 stimule l’ouverture des canaux anioniques sensibles au gonflement cellulaire. Cette activation s’accompagne d’une perte de glutathion et d’une accumulation intracellulaire d’espèces réactives de l’oxygène. Cette dernière est à l’origine d’une transition épithélio-mésenchymateuse des cellules rénales. L’inhibition pharmacologique ainsi que la répression génétique des canaux VRAC réduit significativement les effets du TGFβ1. Enfin dans la dernière partie, nous avons caractérisé le rôle des canaux anioniques sensible au gonflement cellulaire dans la sécrétion de facteurs pro-inflammatoires par les macrophages stimulés par un choc hypotonique. En collaboration, nous avons montré que le blocage de la régulation du volume cellulaire, sous le contrôle de ces canaux, entraine une inhibition de l’activation de l’inflammasome et donc de la sécrétion des facteurs pro-inflammatoires. Bien que les mécanismes de signalisation cellulaire restent à déterminer, ces travaux mettent en lumière l’importance des canaux anioniques sensibles au gonflement cellulaire dans la transition épithéliomésenchymateuse et l’inflammasome. Il apparait que ces canaux pourraient être des cibles thérapeutiques prometteuses dans un certain nombre de pathologies et qu’il est primordial de poursuivre les investigations dans ce domaine. / Anion channels have always been underestimated compared to cationic channels mainly because of the difficulty in characterizing their molecular identities and the absence of potent selective inhibitors. It is a class with great heterogeneity and complexity, including CFTR activated by cAMP, anoctamines activated by intracellulaire calcium and VRAC channels activated by cell swelling. The molecular identity of an essential protein to the ionic currents triggered by cell swelling was discovered in 2014, allowing the scientist community to investigate the role of these channels. In a first part, we highlighted the lack of specificity of the inhibitors of different chloride channels. This study shed lights on the need to develop new inhibitors to discriminate the different chloride channels, but also the need to couple the pharmacological approach to a genetic approach. In a second part, we have demonstrated the glutathione permeability of Volume Regulated Anion Channels. Our results therefore suggest that VRAC channels might be involved in the regulation of oxidative stress as glutathione is the main antioxidant within the cell. In the third part of my thesis, we have shown that TGFβ1 growth factor stimulates the opening of Volume Regulated Anion Channels which is correlated with both a loss of glutathione and an intracellular accumulation of reactive oxygen species. The latter is at the origin of an epitheliomesenchymal transition of renal cells. The pharmacological inhibition as well as the genetic repression of the VRAC channels significantly reduces the effects of TGFβ1. Finally, in the last part, we characterized the role of Volume Regulated Anion Channels in the secretion of pro-inflammatory factors by macrophages stimulated by hypotonic shock. In collaboration, we have shown that blocking the regulation of cell volume, under the control of these channels, leads to an inhibition of the inflammasome and therefore of the secretion of pro-inflammatory factors. Although cell signaling mechanisms remain to be determined, this work highlights the importance of VRAC in the epithelial-mesenchymal transition and inflammasome. It appears that these channels could be promising therapeutic targets in a certain number of pathologies and that it is essential to continue the investigations in this field.

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第19551号 / 医博第4058号 / 新制||医||1012(附属図書館) / 32587 / 京都大学大学院医学研究科医学専攻 / (主査)教授 川口 義弥, 教授 坂井 義治, 教授 羽賀 博典 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

京都大学 / 新制・課程博士 / 博士(医学) / 甲第24879号 / 医博第5013号 / 新制||医||1068(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 後藤 慎平, 教授 渡邊 直樹, 教授 平井 豊博 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

Le rejet chronique se manifeste dans le poumon par la bronchiolite oblitérante (BO), une pathologie inflammatoire et fibrotique menant à l’oblitération des bronchioles. L’étiologie exacte de cette maladie demeure inconnue. Certaines études suggèrent qu'un déséquilibre des leucotriènes (LT) sur les prostaglandines (PG) favorise la fibrose pulmonaire. Les taux des LT et des PG dans le poumon humain post-transplantation sont inconnus. Nous proposons qu'un déséquilibre de cystéinyl leucotriènes (CysLT) sur la PGE2 existe dans le poumon transplanté et pourrait être impliqué dans la pathogenèse de la BO. Aussi, les leucotriènes contribueraient à la fibrose par la transition épithélio-mésenchymateuse (TEM). Afin de vérifier ces hypothèses, nous avons déterminé les taux de CysLT et de PGE2 dans le liquide de lavage broncho-alvéolaire (LBA) provenant de poumons transplantés chez l'homme ainsi que leurs corrélations cliniques. Nous avons également déterminé la capacité des CysLT à induire l’expression des marqueurs de la TEM in vitro. Nous avons découvert des taux de CysLT et PGE2 supérieurs à la normale dans les LBA des greffés. Un pic prédominant de CysLT sur PGE2 est observée à 52 semaines postgreffe et deux facteurs de risque de la BO, les infections au CMV et à l’Aspergillus, sont associés au ratio CysLT/PGE2> 1. In vitro, les CysLT induisent une répression des marqueurs épithéliaux mais n’induisent pas l’expression de marqueurs mésenchymateux chez les cellules épithéliales bronchiolaires. / Chronic rejection occurs, in the lung, in the form of bronchiolitis obliterans (BO), an inflammatory and fibroproliferative disease that leads to the obliteration of the bronchioles. A concept of the pathogenesis of BO has been suggested and several risk factors are associated to it, however, the exact etiology of this disease remains unknown. Studies have suggested that an imbalance of leukotrienes (LT) over prostaglandins (PG) promotes pulmonary fibrosis. The levels of LT and PG in the human lung post-transplantation are unknown. We propose that an imbalance of cysteinyl leukotrienes (CysLT) on PGE2 exists in the transplanted lung and may be implicated in the pathogenesis of BO. We also suggest that leukotrienes contribute to fibrosis through epithelial-mesenchymal transition (EMT). In order to test these hypotheses, we have determined the levels of CysLTs and PGE2 in human transplanted lung bronchoalveolar lavage fluid (BALf) samples and their clinical correlations. We have also determined the capacity of CysLT to induce the expression of EMT markers in vitro. We found high average levels of CysLT and PGE2 in the BAL of transplant patients. A predominant peak of CysLT over PGE2 was observed at 52 weeks post-transplantation and two risk factors for BO, CMV infections and Aspergillus were associated with CysLT/PGE2 ratio> 1. According to our experimental parameters, CysLT can induce the repression of epithelial markers but do not induce the expression of mesenchymal markers in vitro in small airway epithelial cells.

The frequent cause of failure of prostate carcinoma radiotherapy and chemotherapy is the emergence of resistance and a progress into the essentially incurable metastatic form of disease. Although the mechanisms of the radioresistance and chemoresistance are still not well understood, recent studies indicate that transcription factor Snail, a key mediator of the epithelial-mesenchymal transition and subsequent metastasis formation, plays a critical role in the development of the chemoresistance and radioresistance in the tumor cells. As the activation of the optimal DNA damage response pathway is the determining factor for the cell survival after chemotherapy and radiotherapy, we hypothesized the role of Snail in the transcription regulation of these processes. In this study, we first analyzed the relationship between Snail and ATM kinase, as the ATM was recently reported to regulate stability of Snail by its phosphorylation. Although, we observed a modest effect of ATM inhibition on Snail levels after cancer cells exposure to ionizing radiation, we did not fully reproduced the recently published findings. Furthermore, we evaluated the role of Snail in transcription regulation of cyclin-dependent kinase inhibitor p21waf1/cip1 . Our data point towards the suppressive role of Snail in p21waf1/cip1...

Os tumores odontogênicos benignos compreendem um grupo de neoplasias originárias dos tecidos dentários. Pesquisas vêm buscando identificar moléculas envolvidas nos mecanismos moleculares que regulam a remodelação da matriz extracelular (MEC) e como isto influencia no comportamento localmente invasivo presente em alguns destes tumores. A Transição Epitélio-Mesenquimal (TEM conversão do fenótipo epitelial em mesenquimal) é bem caracterizada em diversos carcinomas, culminando em mestástase. MMPs são enzimas que degradam os componentes da MEC, geram moléculas bioativas, participam da TEM e o controle da remodelação da MEC dá-se pelo balanço entre elas, seus inibidores (TIMPs e RECK) e seu ativador (EMMPRIN). Assim, o objetivo deste trabalho foi delinear o perfil de expressão das MMPs (-2, -7, -9 e -14), seus inibidores (TIMPs -2, -3, -4 e RECK), seu ativador (EMMPRIN) e marcadores da TEM (Snail, Slug, N-caderina, Fibronectina, a-Actina de músculo liso e Vimentina) em Ameloblastomas (AB) e Tumores Odontogênicos Cístico Calcificantes (TOCC). Ainda, realizamos a comparação da expressão de cada molécula avaliada em cada compartimento celular (epitélio e estroma) e correlação entre as moléculas avaliadas no mesmo tumor. Utilizamos 19 casos de AB e 18 casos de TOCC (Serviço de Anatomia Patológica da FOUSP), localização das enzimas/proteínas por imunoistoquímica e analisadas nos compartimentos epitelial e estromal. Todas as proteínas/enzimas analisadas foram detectadas tanto nos AB quanto nos TOCC, sendo a maioria expressa em ambos os compartimentos. A N-caderina foi localizada apenas no epitélio dos AB e a Vimentina somente no estroma em ambos os tumores. Na comparação entre o epitélio x estroma dos ameloblastomas, verificamos que houve diferença estatisticamente significante (p<0,05) para a MMP-2, MMP-7, EMMPRIN/CD147, Fibronectina, a-Actina de músculo liso, N-caderina, Vimentina, Snail e Slug. Na comparação entre o epitélio x estroma dos TOCC, verificamos que houve diferença estatisticamente significante (p<0,05) para a MMP-9, RECK, EMMPRIN/CD147, Vimentina, N-caderina, Snail e Slug. Assim, entre o epitélio x estroma dos ameloblastomas e TOCC, verificamos que houve diferença estatisticamente significante (p<0,05) para a MMP-2, MMP-7, MMP-9, RECK, EMMPRIN/CD147, Fibronectina, Vimentina, a-Actina de músculo liso, N-caderina, Snail e Slug. Esta é a primeira vez que a EMMPRIN, RECK, TIMP-3, TIMP-4, Ncaderina, Snail e Slug são descritas em TOCC e TIMP-3, TIMP-4, Snail e Slug em ameloblastomas. Concluímos que estas proteínas/enzimas estão diferencialmente expressas tanto no epitélio quanto no estroma destes tumores e sugerimos que estes podem participar do comportamento localmente invasivo. / Odontogenic tumors comprise a group of benign neoplasms originating from dental tissues. Research looking for identify molecules involved in the molecular mechanisms that regulate extracellular matrix remodeling (ECM) and how this impacts on locally invasive behavior present in some of these tumors. Epithelial-Mesenchymal Transition (EMT - conversion of epithelial phenotype into mesenchymal phenotype) is well characterized in several carcinomas, leaving to metastasis. MMPs are enzymes that degrade ECM components, generate bioactive molecules, participating in the EMT and control ECM remodeling is given by the balance between them, their inhibitors (TIMPs and RECK) and its activator (EMMPRIN). The aim of this study was evaluate expression profile of MMPs (-2, -7, -9 and - 14), their inhibitors (TIMPs -2, -3, -4 and RECK), its activator (EMMPRIN) and EMT markers (Snail, Slug, N-cadherin, Fibronectin, -smooth muscle actin and Vimentin) in ameloblastomas (AB) and Calcifying Cystic Odontogenic Tumor (CCOT). We also compared the expression of each molecule assessed in each cellular compartment (epithelium and stroma) and correlation between molecules evaluated in the same tumor. We used 19 AB cases and 18 CCOT cases from files of Pathology Laboratory (FOUSP), localization of enzymes/proteins and analyzed by immunohistochemistry in epithelial and stromal compartments. All proteins/enzymes were detected in both AB and CCOT, mostly expressed in both compartments. N-cadherin was localized only in the epithelium of AB and Vimentin only in stromal in both tumors. Comparing \"epithelium vs stroma\" of AB, we observed a statistically significant difference (p <0.05) for MMP-2, MMP-7, EMMPRIN/CD147, Fibronectin, -smooth muscle actin, N-cadherin, Vimentin, Snail and Slug. Comparing \"epithelium vs stroma\" of CCOT, we observed a statistically significant difference (p <0.05) for MMP-9, RECK, EMMPRIN/CD147, Vimentin, N-cadherin, Snail and Slug. Analizing epithelium vs stroma\" between AB and CCOT, we observed a statistically significant difference (p <0.05) for MMP-2, MMP-7, MMP-9, RECK, EMMPRIN/CD147, Fibronectin, Vimentin , -smooth muscle actin, N-cadherin, Snail and Slug. This is the first time that EMMPRIN, RECK, TIMP-3, TIMP-4, N-cadherin, Snail and Slug are described in CCOT and TIMP-3, TIMP-4, Snail and Slug in AB. We conclude that these proteins/enzymes are differentially expressed in both epithelium and stroma of these tumors and suggest that they may participate locally invasive behavior.

Introdução: Os marcadores moleculares têm sido utilizados para identificar subgrupos de tumores com comportamento clínico distinto, inclusive quanto ao padrão de recidiva. Objetivo: Caracterizar a expressão imunoistoquímica de vimentina (VIM) e E-caderina (CDH1) em carcinomas ductais invasivos (CDI) de mama e sua associação com a expressão de citoqueratina 5 (CK5), e características clínico-patológicas. Métodos: Microarranjos teciduais (TMA) foram construídos a partir de 82 amostras de CDI de mama. Imunoistoquímica (IHQ) foi realizada para determinar os receptores hormonais (RH; receptores de estrógeno e progesterona) e receptor do fator de crescimento epidérmico humano 2 (HER2), VIM, CDH1, CK5 e Ki-67. Os tumores foram classificados como luminal A (RH+, HER2-), luminal B (RH+, HER2+ ou Ki-67 alto), HER2 hiperexpresso (RH-, HER2+) e triplo negativo (TN; RH-, HER2-). Resultados: O fenótipo VIM+/CDH1-/low não foi observado nos tumores luminal A, B e HER2 hiperexpresso, enquanto que este fenótipo estava presente em 61,9% dos TN (p= 0,0001). A mediana de Ki-67 em tumores VIM+/CDH1-/low foi 13,6 (variação, 17,8-45,4), em comparação com 9,8 (variação de 4,1-38,1) nos não- VIM+/CDH1-/low (p= 0,0007). O acometimento linfonodal foi menos freqüente em pacientes com VIM+/CDH1-/low do que nos não- VIM+/CDH1-/low (23% X 61%, teste de 2, p = 0,01). A sobrevida livre de doença em 5 anos foi de 61,5% e 83,7% (teste de log-rank, p= 0,02) e a sobrevida global em 5 anos foi de 51,2% e 83,5% (teste de log-rank, p= 0,03) em pacientes com tumores com fenótipo VIM+/CDH1-/low e não VIM+/CDH1-/low, respectivamente. Conclusão: A expressão de VIM e CDH1 identificaram um subconjunto de CDI de mama com fenótipo mesenquimal com alto grau histológico e alto índice mitótico. / Introduction: Molecular markers have been used to identify subgroups of tumors with distinct clinical behavior, including recurrence pattern. Objective: To characterize the immunohistochemical expression of vimentin (VIM) and E-cadherin (CDH1) in invasive ductal carcinoma (IDC) of the breast and its association with cytokeratin 5 (CK5) expression and clinicopathological features. Methods: A tissue microarray was constructed from 82 IDC breast cancer specimens. Immunohistochemistry (IHC) was used to determine hormone receptor (HR; estrogen and progesterone receptors) status and human epidermal growth factor receptor 2 (HER2), VIM, CDH1, CK5, and Ki-67 expression. Tumors were classified as luminal A (HR+, HER2-), luminal B (HR+, HER2+ or high Ki-67), HER2 enriched (HR-, HER2+), and triple negative (TNBC; HR-, HER2-). Results: The VIM+/CDH1-/low phenotype was not observed in luminal A, luminal B and HER2 enriched tumors, whereas this phenotype was present in 61.9% of triple negative (TNBC) tumors (p = 0.0001). The median Ki-67 index in VIM+/CDH1-/low tumors was 13.6 (range, 17.8-45.4) compared with 9.8 (range, 4.1-38.1) in non-VIM+/CDH1-/low tumors (p= 0.0007). The presence of lymph node metastasis was less frequent in patients with VIM+/CDH1-/low tumors than in those with non-VIM+/CDH1-/low tumors (23% vs. 61%; 2 test, p= 0.01). The 5-years disease-free survival was 61.5% and 83.7% (log-rank test; p= 0.02) and the 5-year overall survival was 51.2% and 83.5% (log-rank test; p= 0.03) in patients with VIM+/CDH1-/low phenotype and non-VIM+/CDH1-/low phenotype tumors, respectively. Conclusion: The expression of VIM and CDH1 identified a subset of IDC breast cancer of the mesenchymal phenotype with high histological grade and high mitotic index.

Introdução: A endometriose é uma doença ginecológica comum caracterizada pela presença de estroma e/ou glândula endometrial fora da cavidade uterina, e que não possui sua etiopatogenia bem estabelecida. A transição epitélio-mesênquima (TEM) é um processo que consiste em uma série de mudanças no fenótipo de células epiteliais que fazem com que estas células assumam características de células mesenquimais. Assim como observado na TEM, as células endometriais no contexto da endometriose apresentam capacidade migratória, invasibilidade e elevada resistência à apoptose. As moléculas de adesão têm adquirido crescente relevância na TEM, pois relacionam-se à perda de adesão célula-célula com o aumento da invasão e metástase. O objetivo deste estudo foi investigar a expressão de marcadores relacionados com a TEM na endometriose superficial, ovariana e profunda. Pacientes e Métodos: Foram selecionadas 103 mulheres que preenchiam os critérios de inclusão estabelecidos, constituindo 2 grupos de estudo independentes entre si: 18 mulheres com endometriose peritoneal, ovariana e profunda concomitantes; 85 mulheres com endometriose ovariana e/ou profunda, dividido em 44 mulheres com endometriose ovariana e 41 com endometriose intestinal. Através de reações de imunoistoquímica, a expressão proteica dos marcadores e-caderina, n-caderina, betacatenina, receptor de estrogênio e receptor de progesterona foram avaliados nos tecidos de interesse em cada grupo de estudo. Além dos locais de doença, as mulheres foram avaliadas quanto à relação com a fase do ciclo e à classificação histológica da doença. Resultados: As lesões de endometriose de ovário mostraram uma menor expressão de n-caderina em comparação às lesões de intestino e peritônio (p=0,032). O receptor de estrogênio e receptor de progesterona se mostraram significativamente menos expressos no componente epitelial da doença de ovário do que no epitélio da endometriose de peritônio e intestino (p=0,002; p=0,48). A expressão da n-caderina apresentou uma correlação direta com a expressão do receptor de estrogênio no estroma da endometriose de intestino (p=0,036). Conclusão: Estes resultados sugerem que a transição epitélio-mesênquima esteja envolvida na etiopatogenia da endometriose, demonstrando que a doença de ovário se comporta de maneira diferente da doença superficial e da doença infiltrativa profunda, sendo a n-caderina um importante fator envolvido neste processo possivelmente influenciada pela ação do estrogênio / Background: Endometriosis is a common gynecological disease defined as the presence of ectopic endometrial glands and stroma outside the uterine cavity, and its pathogenesis is not well established. The epithelial to mesenchymal transition (EMT) is a process consisting of a series of changes in the phenotype of epithelial cells that make these cells assume the characteristics of mesenchymal cells. As observed in the EMT, endometrial cells in the context of endometriosis have the capacity of migration, invasiveness and high resistance to apoptosis. . The adhesion molecules have become progressively relevant in EMT, in view of the cell-to-cell adhesion loss, with increased invasion and metastasis. The goal of this study was to investigate the expression of markers related to EMT in superficial, ovarian and deep endometriosis. Patients and Methods: 103 women were selected who met the inclusion criteria, constituting two independent study groups: 18 women with peritoneal, ovarian and deep concomitant endometriosis, 85 women with ovarian and / or deep endometriosis, divided in 44 women with ovarian endometriosis and 41 with intestinal endometriosis. Through immunohistochemical reactions, the protein expression of e-cadherin, ncadherin, beta-catenin, estrogen receptor and progesterone receptor markers were evaluated in tissues of interest in each study group. In addition to the sites of the disease, menstrual phase and histological classification (well-differentiated, undifferentiated, mixed pattern and stromal) of the disease were recorded. Results: The ovarian endometrisis showed less n-cadherin marker than lesions of the peritoneum and bowel (p=0,032). Ovarian endometriosis also showed markedly decreased expression of estrogen and progesterone receptors in epithelial cells, compared with peritoneal and deep endometriosis (p=0,002; p=0,48). The expression of N-cadherin showed a direct correlation with estrogen receptor expression in the stroma of bowel endometriosis (p = 0.036). Conclusion: These results suggest that epithelial to mesenchymal transition involved in the pathogenesis of endometriosis, demonstrating that the ovary disease behaves differently disease than peritoneal and deep disease, so that the n-cadherin is an important factor involved in this process, possibly influenced by the action of estrogen

As neoplasias mamárias apresentam um grande desafio tanto para a medicina humana, quanto para a medicina veterinária. Esses tumores apresentam ampla heterogeneidade intertumoral e intratumoral, dificultando assim a busca por tratamentos eficazes. Recentemente, pesquisadores tem voltado sua atenção para uma população de células que apresentam características muito semelhantes as células-tronco. São as chamadas células iniciadoras de tumores (CITs). Estas são descritas como as principais responsáveis por falhas nas quimioterapias e no surgimento de recidivas tumorais, devido ao seu potencial tumorigênico, de auto-renovação e de resistência a drogas antineoplásicas. Entretanto, o estudo dessas células é limitado pelas dificuldades no isolamento e na caracterização pós-enriquecimento dessas células, devido à perda do fenótipo em modelos in vitro. Sendo assim, vários estudos estão buscando maneiras alternativas de enriquecer essa população. Uma das maneiras mais utilizadas, baseia-se na indução do processo de transição epitélio-mesenquimal, através da superexpressão de fatores de transcrição como SNAI1, SLUG, ZEB1 e ZEB2. Sendo assim, nós objetivamos expressar de maneira exógena os fatores de transcrição SLUG e ZEB1 em células oriundas de carcinomas mamários caninos, caracterizar seus efeitos nessas células e observar se esses fatores de transcrição seriam capazes de induzir o fenótipo de CIT. Primeiramente, quatro amostras de carcinomas mamários caninos foram analisados quanto sua morfologia e os níveis de expressão gênica de quatro fatores de transcrição associados a transição epitélio-mesenquimal: SLUG, STAT3, ZEB1 e ZEB2. Após, nós selecionamos duas dessas amostras (CC-20E e CL-28E), que apresentavam morfologia típica de células epiteliais e baixa expressão dos fatores de transcrição citados acima e expressamos de maneira exógena e de forma estável os fatores de transcrição SLUG e ZEB1, através do processo de transdução lentiviral. Entretanto, apenas a transdução com os plasmídeos contendo a região codificante de SLUG foi eficiente. Sendo assim, nós avaliamos os efeitos da expressão exógena de SLUG nas células CC-20E e CL-28E, quanto a alteração de morfologia e expressão de filamentos intermediários como citoqueratina, vimentina e actina. Além disso, nós avaliamos se a expressão exógena de SLUG poderia regular a expressão de outros genes associados a EMT, além de genes supressores de tumores, alvos de SLUG. Por fim, nós avaliamos se a expressão exógena de SLUG poderia induzir ao fenótipo de CITs, verificando se havia alteração na sensibilidade das células aos quimioterápicos doxorrubicina e paclitaxel, além de avaliar o potencial tumorigênico e de auto-renovação dessas células em cultivos de baixa aderência. A expressão exógena de SLUG nas células CC-20E e CL-28E, não induziu a alterações na morfologia epitelial das células. Entretanto, as células alteraram sua disposição em monocamada no cultivo, formando tipos de túbulos semidiferenciados, característicos do processo de EMT híbrido ou parcial. Além, disso, houve um equilíbrio entre a expressão dos filamentos intermediários de citoqueratina e vimentina nas células, além do aumento na expressão dos genes CDH1 (E-caderina) e CDH2 (N-caderina), resultado que sustentou a indução de EMT parcial. O processo de EMT parcial induziu maior resistência ao quimioterápico paclitaxel, além de potencializar a tumorigenecidade e a capacidade de auto-renovação das células em cultivos de baixa aderência. Sendo assim, no presente estudo, nós obtivemos um cultivo com características que mimetizam as CITs, demonstrando que os processos que induzem esse fenótipo são semelhantes tanto na espécie canina, quanto em humanos, sustentando a hipótese de que neoplasias mamárias caninas podem servir como modelo para o estudo das CITs e, consequentemente, do desenvolvimento neoplásico de tumores sólidos. / Mammary neoplasms present a major challenge for both human and veterinary medicine, due to intertumoral and intratumoral heterogeneity, hindering the search for effective treatments. Recently, researchers has highlighted a population of cells with features very similar to stem cells. Known as Tumor-Initiating Cells (TICs), they are described as the main responsible for chemotherapy failures and tumor recurrence, due to their tumorigenic potential, self-renewal ability and drug resistance. The study of TICs is limited mainly by their difficult isolation owing to specific markers absence, and furthermore, cells lose their phenotype when placed in vitro. Therefore, several studies are seeking for alternatives to enrich this population in regular cultures. One way is based on the epithelial-mesenchymal transition induction through of transcription factors overexpression, such as SNAI1, SLUG, ZEB1 e ZEB2. So, the aim of this study was to overexpresse the SLUG and ZEB1 transcription factors in a cell culture derived from canine mammary carcinomas, evaluate its effects and observe whether these transcription factors would be capable of inducing the TIC phenotype. First, four canine mammary carcinomas cell cultures were analyzed for their morphology and gene expression levels of four transcription factors associated with epithelial-mesenchymal transition: SLUG, STAT3, and ZEB1 ZEB2. After, we selected two samples (CC-20E and CL-28E) with typical morphology of epithelial cells and low expression of the transcription factors mentioned above. We then overexpress, stably, the transcription factors SLUG and ZEB1 by lentiviral transduction, However, only SLUG transduction was efficient. Then, we evaluated the effects of SLUG overexpression in CC-20E and CL-28E cells as the change of morphology, expression of intermediate filaments as cytokeratin, vimentin and actin. In addition, we evaluated whether SLUG overexpression could regulate the expression of other EMT-associated genes as well as tumor suppressor genes, and assessed evaluated the tumorigenic potential and self-renewal of these cells in low adherence cultures. Finally, we assessed whether SLUG overexpression could induce drug resistance through doxorubicin and paclitaxel sensivity assay. The SLUG overexpression did not induce modification in epithelial cell morphology, however, cells changed their arrangement in monolayer culture, inducing the semidifferentiated tubules, typical of hybrid or partial EMT process. In, addition, there was a balanced expression between cytokeratin and vimentin, possibly explained by an increase in CDH1 expression (E-cadherin) and CDH2 (N-cadherin) typical of partial EMT. Furthermore, the partial EMT generated cells presenting paclitaxel resistance, and enhanced the tumorigenic potential and self-renewal capacity of the cells on low adherent plates. Thus, in this study, we obtained a cell culture exhibiting features that mimics the TICs, demonstrating the mechanisms which regulate this phenotype are similar in dogs and humans, supporting the hypothesis that canine mammary carcinomas are a great model for the study of TICs and solid tumors development.

Entre todos os cânceres de pele, o melanoma está entre os menos comuns, mas é responsável pela maior parte das mortes. No caso da doença metastática, não há um tratamento satisfatório capaz de prolongar a vida do paciente. Isso leva à necessidade de novas estratégias e de novos tratamentos que possam reverter a quimiorresistência do tumor. Entre as proteínas que têm seu perfil de expressão modificado no melanoma está a proibitina, cuja expressão aumenta durante a progressão tumoral. Proibitina é uma chaperona mitocondrial pertencente a uma família de proteínas que possuem um resíduo hidrofóbico SPFH, que confere a ela uma capacidade de ancoragem e de organização de espaços em membranas. Além disso, no compartimento nuclear, é um inibidor da família de fatores de transcrição E2F, juntamente com a proteína retinoblastoma (Rb). Em melanomas, proibitina localiza-se no citoplasma, associada à mitocôndria, e no núcleo. No citoplasma, proibitina faz parte da resposta a diversas drogas, como cisplatina, dacarbazina, temozolamida, vimblastina e tunicamicina pode estar relacionado com o aumento de espécies reativas de oxigênio (ROS), já que essas drogas podem de alguma forma induzir ROS intracelular. O aumento de expressão de proibitina, nesse contexto, poderia fazer parte de uma resposta protetora da mitocôndria, o que em última análise protegeria a célula contra a morte celular, já que a inibição de proibitina sensibiliza a célula ao tratamento com cisplatina ou tunicamicina. Além disso, o estresse provocado pela privação de soro fetal bovino em linhagens de melanoma leva ao aumento de expressão de proibitina e é acompanhado pela indução de ROS. No núcleo, proibitina esta colocalizada com MCM5 e MCM7, mas não MCM2. A inibição de proibitina leva ao aumento de expressão de metaloproteinases de matriz extracelular, não só em melanomas, mas também em linhagens de câncer de mama e de câncer de pulmão. Ainda, proibitina parece estar relacionada com o fenômeno da transição epitélio mesênquima, já que a inibição de proibitina leva ao aumento de expressão de marcadores mesenquimais como N-caderina e vimentina e a perda de expressão de marcadores epiteliais, como a E-caderina. Outras funções controladas por E2F1 que proibitina pode estar modulando são a capacidade de E2F1 induzir reparo de DNA devido a lesões causadas por radiação UVB e a indução de senescência. A inibição de proibitina em linhagem de câncer de pulmão protegeu a célula contra o dano genotóxico causado pela radiação UVB, pelo aumento da proteína de reparo de DNA Gadd45a, que é induzida por E2F1. Ainda, a inibição de proibitina diminuiu a quantidade de células senescência induzida por adriamicina em linhagens de melanoma. Ainda, a expressão de proibitina responde a fatores do microambiente tumoral como TGF?, IL4 e LPS juntamente com INF? e, além disso, têm sua expressão diminuída durante a maturação de macrófagos. Esses resultados mostram que proibitina pode atuar protegendo o tumor ou bloqueando vias importantes para seu desenvolvimento, dependendo da sua compartimentalização subcelular / Among all skin cancers, melanoma is the least common, but is responsible for most deaths. In metastatic disease, no satisfactory treatment can prolong the patient\'s life. This leads to the need for new strategies and new treatments that may reverse tumor chemoresistance. Among proteins that have their expression profile altered in melanoma is prohibitin whose expression increases during tumor progression. Prohibitin is a mitochondrial chaperone belonging to a family of proteins which possess a hydrophobic residue SPFH, which gives it a capacity for anchorage and organization in membrane regions. Furthermore, in the nuclear compartment, prohibitin is an inhibitor of the E2F transcription factor family, together with the retinoblastoma protein (Rb). In melanomas, prohibitin is located in the cytoplasm, associated to the mitochondria, and inside the nucleus. In the cytoplasm, prohibitin is part of the response to various drugs such as cisplatin, dacarbazine, temozolomide, vinblastine and tunicamycin and may be associated with increased reactive oxygen species (ROS), since these drugs can somehow induce intracellular ROS. Prohibitin overxpression in this context could be part of a protective response of the mitochondria, which ultimately protect cells against death, as prohibitin inhibition sensitizes cells to cisplatin or tunicamycin treatment. Moreover, the stress caused by deprivation of fetal bovine serum in melanoma cell lines leads to prohibitin overexpression and is accompanied by ROS induction. In the nucleus, prohibitin is colocalized to MCM5 and MCM7, but not to MCM2. Inhibition of prohibitin leads to increased expression of matrix metalloproteinases, not only on melanomas but also on breast cancer and lung cancer cell lines. Further, prohibitin appears to be related to the phenomenon of epithelial mesenchymal transition, since prohibitin inhibition leads to increased expression of mesenchymal markers such as N-cadherin and vimentin and loss of expression of epithelial markers, such as E-cadherin. Other functions controlled by E2F1 that are modulated by prohibitin include be the ability of E2F1 to induce DNA repair against UVB radiation and the induction of cellular senescence. Inhibition of prohibitin in lung cancer cell line protected against genotoxic damage caused by UVB radiation, due to DNA repair protein Gadd45a overexpression, which is induced by E2F1. Also, prohibitin inhibition decreased the amount of cell senescence induced by adriamycin in melanoma cell line. Further, prohibitin expression is triggered by tumor microenvironmental factors such as TGF?, IL4, and LPS together with INF? and, in addition, prohibitin expression decreases during macrophages maturation. These results show that prohibitin may act protecting the tumor or blocking pathways important for its development, depending on its subcellular compartment distribution