Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Breast cancer is the most commonly occurring cancer worldwide, more than 2.26 million new cases occurred in women in 2020. Treatment for breast cancer is normally individualized to the patient based on the presence of different receptors, these receptors include HER2, progesterone, and estrogen. The presence of these receptors generally comes with an amenable prognosis, and a wide array of available treatments. There are types of breast cancers that do not have any of these receptors and tend to be much more aggressive. This type of cancer is called triple negative and represents about 10 percent of all breast cancer occurrences in the United States. The lack of receptors makes this type of cancer extremely difficult to treat and generally comes with a poor prognosis. In the present study, we used triple negative breast cancer cell line MDA-MB231, which is known to use actin remodeling to evade immunologic response. These cells were treated with two novel, structurally similar flavonoids, CT1 and CT3 derived from an ethnobotanically recognized species of Chromolaena. CT1 and CT3 are extracted from the leaves of Chromolaena tacotana and then isolated and purified by chromatography. These compounds are used to treat cancer cells, at different concentrations that include 5, 10, 20, 40 and 80mM. MTT assays are used to determine their effect on cell viability, and the mechanism of action was analyzed by immunoblotting and TUNEL.. CT1 has a significantly stronger inhibitory effect on MDA-MB231 cell viability as compared to CT3. Preliminary analysis of the mechanism of action of CT1 has revealed that it neither follows the canonical intrinsic apoptotic pathway nor the extrinsic pathway that involves the activated form of c-JUN. By up-regulating actin, triple negative breast cancer is able to evade immunologic response and cancer treatment. CT1, a novel flavonoid extracted from the leaves of Chromoleana tacotana has shown cytotoxic effects against triple negative breast cancer cells effectively bypassing the actin response. The mechanism of action is currently under study.

Le récepteur de la progestérone (PR) est un acteur majeur du développement de la glande mammaire. Dans les cellules épithéliales normales, PR est exprimé sous deux isoformes PRA (94 kDa) et PRB (116 kDa) de façon équimolaire. Il est établi que celles-ci ont un impact important sur le développement des cancers du sein, mais leurs rôles dans l’évolution métastatique reste très mal connus. Le ratio d’expression PRA/PRB étant souvent déséquilibré dans les tumeurs mammaires, nous avons analysé le turnover des deux isoformes. Nous avons démontré que PRA et PRB sont les cibles de modifications post-traductionnelles dirigées par les MAPK qui tendent à stabiliser l’une ou l’autre isoforme de manière sélective. Ainsi, Erk1/2 (p42/44) inhibe la dégradation de PRB tandis que la p38 stabilise PRA. Il en résulte que le ratio PRA/PRB varie de façon importante en fonction des signalisations extracellulaires impliquant les facteurs de croissance et les cytokines inflammatoires souvent exacerbés dans les cancers. Pour mieux étudier les effets différentiels de PRA et PRB, nous avons établi un modèle cellulaire original exprimant de manière bi-inductible l’une ou l’autre isoforme de PR, à partir de la lignée cellulaire MDA-MB 231 provenant d’une métastase de cancer du sein. En étudiant les variations induites par PRA ou PRB sur le transcriptome de ces cellules, nous avons identifié les gènes cibles spécifiques de ces isoformes. Parmi-eux se trouvent de nombreux gènes impliqués dans les cancers, notamment agissant sur la prolifération, la survie et la motilité cellulaires comme uPA et PAI-1. De plus, en analysant la migration cellulaire, nous avons mis en évidence un effet pro-migratoire de PRB particulièrement important en absence d’hormone. En recherchant la cause de ces effets, nous avons découvert que PRB était colocalisé et interagissait avec la kinase d’adhésion focale (FAK) qu’il active au niveau des points d’adhésion focaux. Ces travaux soulignent l’incidence du ratio PRA/PRB et du statut du ligand sur les métastases du cancer du sein, aussi bien au niveau de la sélectivité transcriptionnelle que celui des régulations non génomiques impactant la migration cellulaire. Nous suggérons la possibilité de cibler les tumeurs mammaires par des antagonistes sélectifs de PR et des inhibiteurs des voies de signalisation des MAPK ou de FAK. / Progesterone receptor (PR) is a major actor of mammary gland development. PR is equally expressed as two main isoforms PRA (94 kDa) and PRB (116kDa) in the mammary gland epithelium. However, breast cancer progression has been associated with abnormalities of their expression ratio through undefined mechanisms. In this study, using a stably transfected cell line, we showed that PRA and PRB stabilizations are differentially regulated by Erk1/2 (p42/44) and p38 MAPKs respectively, leading to strongly influence PRA/PRB ratio. These results highlight the impact of growth factors and inflammatory cytokines on PRA/PRB imbalance in cancer cells. To study the differential effect of PR isoforms, we established an original bi-inducible cell line expressing either PRA and/or PRB. By analyzing variations induced by PRA and PRB on such cell transcriptomes, we identified the isoform-specific targets genes by DNA microarrays. Most of them are implicated in cancers, notably acting on cell proliferation, survival and motility. Furthermore, focusing our studies on cell migration, we showed that PRB acts as a pro-migratory factor particularly powerful in the absence of ligand. We discovered that PRB colocalized and interacted with the focal adhesion kinase (FAK) that was activated in focal adhesion points. Our results highlight the impacts of both PRA/PRB ratio and ligand status on metastatic evolution, in the contexts of transcriptional regulation as well as non-genomic events. We suggest the possibility to target mammary tumors by PR-selective antagonists and/or inhibitors of MAPK and FAK signalings.

Das triple-negative Mammakarzinom exprimiert weder Östrogen- noch Progesteronrezeptoren und es kommt zu keiner Überexprimierung des HER2-neu Gens. Daher haben bei diesem Subtyp des Mammakarzinoms spezifische Therapien, welche gezielt an diesen Rezeptoren wirken, keinerlei Nutzen. Etwa 60% aller Mammakarzinome exprimieren GnRH-Rezeptoren, welche als Ziel genutzt werden könnten. Der GnRH-Rezeptor kann für eine gezielte Chemotherapie mit zytotoxischen GnRH-Agonisten wie AN-152, bei welchem Doxorubicin an [D-Lys6]GnRH gebunden ist, genutzt werden. In der vorliegenden Arbeit habe ich in vitro als auch in vivo analysiert ob der zytotoxische GnRH-Agonist AN-152 Apoptose in triple-negativen Mammakarzinomzellen, welche GnRH-Rezeptoren exprimieren, induziert. Die GnRH-Rezeptorexpression in Tumorbiopsien triple-negativer Mammakarzinome wurde immunhistochemisch getestet. Die Zellproliferation wurde unter Verwendung des AlamarBlue®-Proliferationsassays analysiert. Die Apoptoseinduktion wurde durch die Bestimmung des mitochondrialen Membranpotentialverlustes quantifiziert. Die in vivo Experimente wurden mit Nackmäusen nach Xenotransplantation von humanen Brustkrebszellen durchgeführt. Wir konnten zeigen das die Behandlung triple-negativer aber GnRH-positiver MDA¬ MB 231, HCC 1806 und HCC 1937 Mammakarzinomzellen mit AN-152 in vitro zum apoptotischen Zelltod durch Aktivierung der Caspase-3 führt. Diese Antitumoreffekte konnten im Nacktmausmodell bestätigt werden. AN-152 inhibierte das Wachstum triple-negativer Mammakarzinomxenotransplantate in den Nacktmäusen komplett, ohne offensichtliche Nebenwirkungen. Der zytotoxische GnRH-Agonist AN-152 scheint ein passendes Medikament mit niedriger Toxizität für eine effiziente Therapie des triple-negativen Mammakarzinoms zu sein. (Föst C, Duwe F, Hellriegel M, Schweyer S, Emons G, Gründker C (2011). Targeted chemotherapy for triple-negative breast cancers via LHRH receptor. Oncol Rep, 25, 1481-7.)

abstract: Breast cancer cell invasion is a highly orchestrated process driven by a myriad of complex microenvironmental stimuli. These complexities make it difficult to isolate and assess the effects of specific parameters including matrix stiffness and tumor architecture on disease progression. In this regard, morphologically accurate tumor models are becoming instrumental to perform fundamental studies on cancer cell invasion within well-controlled conditions. In this study, the use of photocrosslinkable hydrogels and a novel, two-step photolithography technique was explored to microengineer a 3D breast tumor model. The microfabrication process presented herein enabled precise localization of the cells and creation of high stiffness constructs adjacent to a low stiffness matrix. To validate the model, breast cancer cell lines (MDA-MB-231, MCF7) and normal mammary epithelial cells (MCF10A) were embedded separately within the tumor model and cellular proliferation, migration and cytoskeletal organization were assessed. Proliferation of metastatic MDA-MB-231 cells was significantly higher than tumorigenic MCF7 and normal mammary MCF10A cells. MDA-MB-231 exhibited highly migratory behavior and invaded the surrounding matrix, whereas MCF7 or MCF10A cells formed clusters that were confined within the micropatterned circular features. F-actin staining revealed unique 3D protrusions in MDA-MB-231 cells as they migrated throughout the surrounding matrix. Alternatively, there were abundance of 3D clusters formed by MCF7 and MCF10A cells. The results revealed that gelatin methacrylate (GelMA) hydrogel, integrated with the two-step photolithography technique, has great promise in creating 3D tumor models with well-defined features and tunable stiffness for detailed studies on cancer cell invasion and drug responsiveness. / Dissertation/Thesis / Supplementary Movie 3 / Supplementary Movie 1 / Supplementary Movie 2 / Supplementary Movie 5 / Supplementary Movie 4 / Masters Thesis Bioengineering 2015

Introduction: Breast cancer is the most frequently diagnosed cancer found in women across the world, with an estimated 2.3 million new cases occurring in 2020. Additionally, over 684,000 deaths annually are attributed to breast cancer across the globe, making it the most common cause of cancer-related death in women. Further, treatment of breast cancer relies heavily on whether or not the cancer cells express estrogen, progesterone, and HER 2 receptors and this expression profile is often related to how quickly the cells grow and spread. In the United States, breast cancer cells that are hormone receptor positive and HER-2 negative make up about 73% of breast cancer cases, and cells that do not express any receptor and are known as triple negative, make up around 12% of cases (American Cancer Society, 2019). With that being said, CT1 and CT3 are novel compounds that have a cytotoxic effect on cell lines representing up to 85% of all breast cancer subtypes in the United States. Methods: The leaves of Chromolaena tacotana that contains the flavonoids CT1 and CT3 were dried and placed in a soxhlet extractor using dichloromethane (CH2Cl2) to extract the chlorophyll. The flavonoids were extracted using a column chromatography eluted with trichloromethane (CHCl3), a 1:1 dilution of CHCl3:methanol and methanol, followed by isolation and purification of the compounds. Human breast cancer cell lines MCF7, MDA-MB-231, and SKBr3 were treated with CT1 and CT3 at concentrations of 5, 10, 20, 40 and 80 µM, followed by incubation for 24 hours. To assess cell viability an MTT assay was conducted by adding a 5-diphenyl-tetrazolium bromide reagent. The purple-colored formazan crystals were solubilized with acidified isopropanol, then analyzed by spectrophotometry. Results: CT1 appeared to have the most cytotoxic effects compared to CT3 on MCF7. The opposite effect was observed for SKBr3 with CT3 showing the most effects as compared to CT1. No differential effect was observed on MDA-MB-231 since both CT1 and CT3 showed similar inhibition of cell viability. Conclusions: The results from the different breast cancer cell lines SKBr3, MCF7, and MDA-MB-231 vary based on how they responded to CT1 and CT3. CT3 was more effective on SKBr3 than CT1. CT1 was more effective on MCF7 than CT3. For MDA-MB-231, both CT1 and CT3 showed similar significant cytotoxic effects. The antiproliferative effects of CT1 and CT3 appear to be concentration dependent on all cells studied. In view of the results from MDA-MB-231 triple negative breast cancer cell line, the cytotoxic effect of the flavonoids is not dependent on the presence of estrogen, progesterone, or HER2 receptors on breast cancer cells. Further studies on the mechanism of action are necessary to elucidate the molecular targets of CT1 and CT3.

No description available.

O câncer de mama é uma neoplasia altamente maligna e continua a ser a segunda principal causa de mortalidade entre as mulheres. Os efeitos antitumorais de metaloproteinases e desintegrinas de veneno de serpentes têm sido investigados em vários tipos de células tumorais. Neste estudo, foram avaliados os efeitos antitumorais e anti-angiogênicos induzidos pela Bothropoidina, uma metaloproteinase desintegrina-like isolada da peçonha de Bothrops pauloensis em células de câncer de mama humano MDA-MB-231 e células endoteliais. Após 24 horas de tratamento com 100pg/mL de Bothropoidina foi constatado um efeito citotóxico moderado de 30% em MDA-MB-231 contra 10% de citotoxicidade em MCF10A (uma linha de células da mama não tumorigênica), uma diferença significativa que sugere uma possível preferência desta proteína por alvos em células tumorais. Observou-se apoptose e apoptose tardia após tratamento com Bothropoidina (10pg/mL e 40pg/mL) em células MDA-MB-231. Além disso, esta toxina não só inibiu a adesão de células MDA-MB-231 de uma forma dose dependente, como a migração celular em aproximadamente 45%. Bothropoidina reduziu a viabilidade e adesão de células endoteliais em Matrigel e inibiu a angiogênese in vitro estimulada por bFGF em Matrigel, mostrando um número de vasos formados significativamente menor em relação ao controle. Os resultados demonstraram que Bothropoidina tem um potente efeito antitumoral e antiangiogênico in vitro, representando uma ferramenta biotecnológica para elucidar o efeito antitumoral de metaloproteinases desintegrinas-like em células cancerígenas. / Breast cancer is a highly malignant carcinoma and remains the second leading cause of mortality among women. The antitumor effects of metalloproteinases and disintegrins from snake venom on various types of cancer cells have been investigated. In this study, we evaluated the antitumor and antiangiogenic effects on MDA-MB-231 human breast cancer cells and endothelial cells induced by Bothropoidin, a disintegrin-like metalloproteinase isolated from Bothrops pauloensis snake venom. At 24h after treatment at 100pg/mL, Bothropoidin exerted a moderate cytotoxic effect of 30% on MDA-MB-231 versus 10% cytotoxicity against MCF10A (a non-tumorigenic breast cell line), a significant difference that suggests a possible preference by this protein for targets in cancer cells. Early and late apoptosis of MDA-MB-231 was observed after Bothropoidin treatment (10gg/mL and 40gg/mL). Furthermore, this toxin inhibited not only the adhesion of MDA-MB-231 cells in a dose-dependent manner but also cell migration by approximately 45%. In addition, Bothropoidin decreased endothelial cells viability and adhesion in Matrigel and inhibited in vitro angiogenesis in Matrigel stimulated by bFGF, showing significantly fewer formed vessels. The results demonstrated that Bothropoidin has potent in vitro antitumor and antiangiogenic effect and represents a biotechnological tool for elucidating the antitumor effect of disintegrins-like metalloproteinases in cancer cells. / Dissertação (Mestrado)

Previous studies have shown that the upregulation of CD151 and β1 is associated with poor prognosis in many cancers such as breast cancer. Studies have provided evidence that these proteins are associated with the adhesion and migration of tumor cells. In this study, a microfluidic flow chamber was utilized to determine how CD151 and β1 affected the firm and initial adhesion of metastatic breast cancer cells to a planar endothelial monolayer under shear stress. This system mimicked the adhesion of metastatic breast cancer cells to the endothelial cells of the circulatory system. CD151 and β1 increased the firm adhesion of metastatic breast cancer cells onto an endothelial monolayer when subjected to high shear stresses. CD151 and β1 increased the initial adhesion of metastatic breast cancer cells onto an endothelial monolayer. A transwell assay was utilized to determine how CD151 and β1 affected random migration through different matrixes and random transendothelial migration. CD151 and β1 decreased the random migration of metastatic breast cancer cells through matrices. Additionally, background information is provided related to the metastatic cascade, how it can be modeled with microfluidics, and how CD151 and β1 have been known to effect cancer and metastasis.

Made available in DSpace on 2014-06-12T15:54:21Z (GMT). No. of bitstreams: 2 arquivo5215_1.pdf: 1381913 bytes, checksum: 3a78f7ed849513c01bc3e4ced1760801 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2006 / O ácido úsnico é um metabólito de líquen que apresenta uma grande variedade de atividades biológicas, dentre as quais, citotoxidade frente a células oriundas de tumores malignos humanos. Apesar da existência de revisões recentes sobre a atividade citotóxica do ácido úsnico, o mecanismo de ação desta droga ainda não foi completamente elucidado. Não existe na literatura referência ao envolvimento do gene supressor de tumor p53 com os efeitos do ácido úsnico. Na sua forma normal, a proteína p53 atua em resposta a diferentes estresses celulares levando à transcrição de genes que induzem a retenção do ciclo celular ou apoptose. Entre as formas de atuação do p53 está a repressão de genes que codificam proteínas associadas à polimerização e estabilização de microtúbulos. Estas funções são perdidas quando ocorrem mutações em sua via metabólica, o que acontece em mais de 50% dos tumores cancerosos humanos. O objetivo deste trabalho foi investigar se o mecanismo da ação anticancerígena do ácido úsnico envolve a ativação da via metabólica p53. Para estudos da sensibilidade de linhagens cancerígenas ao ácido úsnico, foram realizados ensaios pelo método colorimétrico do MTT [3-(4,5- dimethylthiazol-2-yl)-2,5diphenyl-tetrazolium bromide], utilizando-se várias concentrações do fármaco (1 a 60 μM) por 72h, frente às seguintes linhagens de células malignas humanas: MCF7(câncer de mama, positiva para receptores de estrogênio, p53 normal), MDA-MB-231(câncer de mama, negativa para receptores de estrogênio, p53 inativo), H1299 (câncer de pulmão, nula para p53). Para determinar o envolvimento do p53 na ação citotóxica do ácido úsnico, os níveis das proteínas p53 e p21 (um inibidor de quinases dependentes de ciclinas cuja expressão é controlada pelo p53) em células MCF7 tratadas com 29 μM de ácido úsnico por 24h foram determinados utilizando-se ensaios western blot com o anticorpo monoclonal DO-12 (específico para p53) e WAF1 (específico para p21). Para verificar se a ação anticancerígena do ácido úsnico resulta em dano ao DNA celular, a fosforilação da SER15 do p53 (um marcador para danos em DNA) foi investigada, após tratamento de células MCF7 com 29 μM de ácido úsnico por 24h. Nestes estudos, ensaios western blot foram realizados com o anticorpo policlonal FOSFO-SER15, específico para serina fosforilada. Para verificar se o aumento nos níveis da proteína p53 detectados após o tratamento com ácido úsnico eram acompanhados por um aumento em sua atividade transcricional, foram executados ensaios com ß-Gal. Nesta metodologia utilizaram-se fibroblastos T22 de camundongos, portadores do plasmídeo RGDFos-LacZ (contendo o resíduo de 36 pb do sítio de ligação para o p53), tratados com diferentes concentrações de ácido úsnico. Para a investigação dos efeitos do ácido úsnico na formação e estabilização de microtúbulos, células MCF7 foram tratadas com 29 μM de ácido úsnico por 24h, fixadas em metanol e tratadas com anticorpo monoclonal anti-ß-tubulina. O ácido úsnico mostrou atividade citotóxica frente às várias linhagens celulares oriundas de tumores malignos humanos, promovendo elevação nos níveis das proteínas p53 e p21. Entretanto, este aumento não foi acompanhado de incremento na atividade transcricional nem da fosforilação da SER15 do p53. Também não foram detectadas modificações na formação dos microtúbulos. As propriedades anticancerígenas do ácido úsnico como agente não genotóxico que atua de uma forma independente do p53 fazem dele um candidato em potencial para novas terapias de câncer