Une sous population de cellules au sein des tumeurs mammaires présente une capacité accrue de se renouveler et de reproduire l’hétérogénéité du cancer du sein. Maintenant il est bien connu que les cellules souches présomptives du cancer du sein possèdent des programmes d’expression des gènes qui correspondent à leurs caractéristiques biologiques uniques. Notre groupe a été impliqué dans la caractérisation épigénétique des cellules souches présomptives du cancer du sein et l’importance de la dérégulation des mécanismes épigénétiques comme la méthylation de l’ADN et le microARN au cours de la carcinogenèse. Plus spécifiquement cette étude détaille l’idée que la survie des cellules souches du cancer du sein peut être due à une signalisation via des circuits spécifiques de régulation, y compris la voie d’inflammation IL6-JAK-STAT. Ces cellules présentent une activation constitutive de cette voie associée à une configuration particulière de la chromatine. Une autre part de cette étude est d’explorer l’idée que des changements dans l’expression des microARN sont fondamentaux pour la maintenance des principales caractéristiques de ces cellules, et leur ciblage peut représenter une nouvelle approche de thérapie contre le cancer du sein. De plus, en testant directement les conséquences in vivo de la régulation de miR30a nous ouvrons la voie pour la recherche et la validation de l’utilisation potentielle des microARN comme thérapie anti cancéreuse. Ensemble, nos résultats apportent une nouvelle compréhension du rôle des modifications épigénétiques dans la maintenance des cellules souches du cancer du sein. De façon importante ces découvertes intègrent l’idée que des mécanismes de régulations différents mais coordonnés ont un rôle dans la survie des cellules souches du cancer du sien et donnent une perspective élargie pour la découverte de nouvelles cibles thérapeutiques / A subpopulation of cells within breast tumors is known to display an increased ability to self-renew and reproduce breast cancer cell heterogeneity. It is now known that putative breast cancer stem cells (CSCs) display distinct programs of gene expression that correlate with their unique biological characteristics. Our group has been involved in the epigenetic characterization of putative breast CSCs and the importance of the deregulation of epigenetic mechanisms such as DNA methylation and microRNA during carcinogenesis. More specifically, this study is detailing the idea that the survival of breast CSC may be dependent on signaling through specific regulatory circuits, including the well known inflammatory IL6-JAK-STAT pathway. These cells display a constitutive activation of this pathway associated with a distinct chromatin configuration. Another part of the study is exploring the idea that changes in microRNA expression are fundamental in sustaining the main attributes of these cells, and their targeting may represent a novel approach for breast cancer therapy. In addition, by directly testing the in vivo consequences of miR30a regulation, we open a window of opportunity for testing and validating the potential use of microRNAs in anti-neoplastic therapy. Together our results bring a new understanding of the role of epigenetic modifications in the maintenance of breast CSC. Importantly, these findings integrate the idea that different but coordinated regulation mechanisms play a role in the survival of CSC and give a larger perspective for finding novel therapeutic targets

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

The production of viable germ cells during human embryonic development determines adult reproductive success. This is particularly true for females, as development of germ cells (GCs) into primordial follicles before birth is imperative for future fertility. During fetal development GCs migrate to the genital ridge to form the gonad, after which several tightly regulated events, including proliferation, differentiation, and association with somatic cells, must occur to form a functional gonad. In the ovary these processes also include the initiation and subsequent arrest of meiosis. These developmental processes are orchestrated by local autocrine and paracrine factors, many of which remain to be identified in the human. In order to decipher further the pathways by which the gonad and GCs develop, potential regulators including prostaglandin (PG) E2, the interleukin (IL)6-type cytokines, and the prokinetecins (PROKs), were examined in the human fetal ovary and PROKs in the human fetal testis. Patterns of gene expression, protein localisation, function, and interaction of the potential mediators throughout human development (8-20 weeks gestation) were determined. Primary fetal tissue was investigated, in addition to immortalized GCs (T-Cam2 cells) and a murine model of fetal ovarian development. PGE2 interacts with known regulators of GC development in non-reproductive organs. It was postulated PGE2 may regulate GC progression by modulating these factors. Examination of PGE2 receptors and precursor enzymes in the fetal ovary revealed that all were present and some were developmentally regulated, with mRNA expression increasing with gestation. These developmentally regulated components were localised to the GCs. The PGE2 receptors were among those differentially expressed, with one localised solely to mature GCs. Culture of human fetal ovary confirmed that PGE2 regulates known regulators of GC development, increasing expression of survival and anti-apoptotic factors. To test the hypothesis that PGE2 is necessary for female GC development, paracetamol, an inhibitor of PGE2 precursor enzymes, was utilised in a murine model of fetal exposure. Fetal ovaries from this experiment displayed disruption of normal development. The IL6-type cytokines are also postulated to be involved in early gonad development, and are known to regulate proliferation and differentiation of mouse embryonic stem and GCs in vitro. A significant increase in transcript levels of the shared receptor components was determined in second trimester human ovaries, as well as developmental increases of several of the IL6-type ligands. Both common receptor components were located specifically in the GCs identifying them as the target of IL6 action in the human fetal ovary. The PROKs regulate cell migration, proliferation and differentiation, and modulate secretion of PGE2 and expression of some IL6-type cytokines. To-date, PROKs have not been examined in the human fetal gonad. Transcript levels were higher in the fetal testis compared to the ovary, with receptor and ligand components increasing with gestation. Most components also increased with gestation in the ovary. However, location of PROK components was strikingly different between the two tissues, with GCs being the primary target of PROK action in the fetal ovary, and Leydig and interstitial cells being the target in the testis. PROKs interaction with other regulators of gonad development was examined utilising a GC line in the case of the ovary and primary interstitial cell cultures in the case of the testis. These studies have identified new factors involved in human fetal gonad development, and how they interact with known regulatory pathways of development.

Breast cancer is characterized in part by chronic inflammation and tissue remodelling in the mammary gland. Adipocyte enhancer binding protein 1 (AEBP1), a pro-inflammatory protein, is up-regulated in breast cancer and enhances cytokine secretion in the mammary tumour microenvironment. AEBP1 over-expression in cultured macrophages resulted in increased enzymatic activity of MMP-9, a matrix metalloproteinase implicated in processing cytokines and stimulating tumour cell growth and mobility. MMP-9 activates the cytokine tumour necrosis factor-alpha (TNF?), and is required for the transformation of epithelial cells by the cytokine interleukin 6 (IL6). Treatment of epithelial cells with TNF? and IL6, both of which promote tumourigenesis, induced AEBP1 expression. Chromatin immunoprecipitation results suggested AEBP1 induction is directly mediated by pro-inflammatory transcription factors NF-?B and STAT3, downstream effectors of TNF? and IL6, respectively. AEBP1 induction may enhance inflammation, thereby contributing to cell proliferation and survival.

Ensuring correct analytical responses is of the utmost importance in laboratory workand interferences with analyses can give incorrect results. Work to improve the precision of the analyses is an ongoing process. An interference in the analysis of Interleukin-6 (IL-6), a cytokine that reflects inflammatory processes in the body, is biotin. Biotin interferes with EnzymeLinkedImmunoSorbentAssay (ELISA) analysis by binding in to streptavidin thereby causing falsely low analytical responses. An attempt to reduce that interference is to raise the threshold for biotin by introducing a new reagent. The aim of this project was to introduce a new reagent with elevated biotin interference threshold and carry out a precision measurement as well as a patient comparison. In addition, a sustainability study was carried out to investigate possible changes in IL-6 concentration when samples are stored in room temperature with open or closed vessels. Control material was analysed during three consecutive days. The patient comparison was performed by analysing 20 patient samples with both the older reagent and the new one. The sustainability study was preformed last and here were 7 patient samples used to perform this part of the study. The control material was analysed with good results, a total coefficient of variation (CV%) was calculated at 1.6% for the lower control and 3.0% for the higher one. The comparison showed good correlation with only a minor negative bias for the new reagent. The sustainability study showed, in line with what the supplier has indicated, a sample shelf life of 6 h at room temperature without sealing. Interesting to mention is that samples over 50 pg/mL showed a shelf life more than 24 h at room temperature without sealing. The decision was made by the medically responsible doctor that the reagent was approved for use in the laboratory.

Breast cancer is the second most common malignancy in the world, accounting for over 1.7 million new diagnoses and an estimated 500,000 deaths per year (1). Overexpression of the receptor tyrosine kinase ErbB2, also known as Her2 or Neu, occurs in over 30% of breast cancers and correlates with metastasis, poor prognosis, and decreased survival (1, 2). Although therapeutics targeting ErbB2 show clinical efficacy, many patients display no initial response or develop drug resistance over time (2). A deeper understanding of the molecular basis of ErbB2-driven tumorigenesis is thus required for the development of improved therapeutic strategies. In vitro experiments suggest that activation of the c-Jun NH2-terminal kinase (JNK) pathway, a mitogen-activated protein kinase pathway, promotes proliferation, cellular invasion, and stem cell expansion in ErbB2-driven breast cancer (3, 4). Furthermore, unpublished data from our lab using mammary epithelial cells expressing activated ErbB2 show that JNK is required for acinus formation in in vitro 3D cultures. In contrast to these studies showing a tumorigenic role for the JNK pathway, other data from our lab show that JNK loss results in accelerated breast tumor growth, suggesting a tumor suppressive role (5, 6). However, these studies were performed in p53 knockout mice with or without a Kras mutation, where the latter required extensive aging and genomic instability to occur before differences in tumor growth were observable. To date, limited in vivo studies exist to confirm the role of JNK in more biologically relevant breast tumor models, such as in ErbB2-mediated cancer, which accounts for over 30% of all human breast cancers. In addition, the molecular mechanisms by which JNK signaling promotes ErbB2-driven tumorigenesis remains poorly understood. To address the discrepancy in JNK function between the in vitro ErbB2-driven breast cancer data and the in vivo p53 knockout tumor data, I began the development of an in vivo murine model to confirm the role of JNK in ErbB2-driven breast cancer. This mouse model will also allow us to test a potential mechanism by which JNK regulates tumorigenesis. Studies show that ErbB2-mediated secretion of the inflammatory cytokine IL6 promotes transformation and tumor growth by activation of the STAT3 transcription factor, triggering an IL6/STAT3 autocrine signaling loop (7,8). A major regulator of Il6 gene expression includes activator protein 1 (AP-1), a transcription factor composed of downstream JNK targets in the Jun protein family (9). In vitro experiments using ErbB2-overexpressing mammary epithelial cell lines show that chemical inhibition of JNK suppresses secreted IL6 protein levels, supporting a role for the JNK pathway in IL6 regulation (7). Thus, I hypothesize that JNK drives ErbB2-driven breast cancer by promoting IL6-mediated tumor progression. Addressing this will increase our understanding of the role of JNK in ErbB2-driven breast cancer and reveal a potentially new mechanism by which JNK functions in tumor progression. Additionally, I began the development of a mouse model that will allow us to investigate the role of JNK in macrophage polarization as an alternative mechanism by which JNK regulates ErbB2-driven breast cancer. In addition to promoting STAT3-dependent tumor growth, IL6 can indirectly drive tumorigenesis by promoting expression of the IL4 receptor in macrophages, triggering STAT6-mediated macrophage polarization towards the pro-tumorigenic M2 phenotype (10, 11). Unlike classically activated M1 macrophages, which promote inflammation and anti-tumor immunity, alternatively activated M2 macrophages function in immunosuppression and metastasis and correlate with advanced stages of breast cancer (12, 13). Further evidence supporting a role for the JNK pathway in macrophage polarization includes a recent study suggesting that JunB, a downstream JNK target and component of the AP-1 complex, plays a crucial role in the induction of M2 macrophage polarization in human alveolar macrophages (13). I hypothesize that activation of the JNK signaling pathway induces IL6-dependent macrophage polarization towards the pro-tumorigenic M2 phenotype. Addressing this hypothesis will determine for the first time whether JNK functions in regulating macrophage polarization within the tumor microenvironment, offering a potentially new mechanism by which JNK can promote ErbB2-driven breast cancer. Determining the role of JNK in ErbB2-mediated breast cancer will have direct therapeutic relevance, as targeting JNK has the potential to inhibit ErbB2-driven breast cancer and other IL6-mediated diseases. Investigating the underlying mechanisms by which JNK functions in ErbB2-positive breast cancer can also offer new molecular targets and further contribute to effective drug design.

No description available.

Schwannomatosis (SWN) is a genetic disorder that predisposes affected individuals to develop multiple Schwannomas anywhere in the peripheral nervous system. This can be due to a mutation in the LZTR1 or SMARCB1 genes on chromosome 22. SWN has the defining clinical symptom of chronic pain and a lack of vestibular schwannomas, which sets it apart from other, related disorders such as Neurofibromatosis Type II (NF2). Currently, it is unknown what causes the chronic pain of SWN patients but it is hypothesized that cytokines may have promote the neuropathic pain experienced by patients. This study investigates the presence of the chemokine CCL2 and the cytokine IL6 in human SWN schwannomas and non-SWN schwannomas to determine if there is a difference in the presence of these cytokines between the two tumor types. It was demonstrated that all of the SWN schwannomas expressed both CCL2 and IL6 whereas the non-SWN schwannomas expressed only one or the other protein if either. These results indicate that the presence of these cytokines within the SWN schwannomas is different from non-SWN schwannomas and could be a potential contributing factor in the occurrence of neuropathic pain experienced by SWN which is part of the differential diagnosis for NF2 and SWN.

Nos últimos anos, notou-se aumento da incidência de carcinoma espinocelular de orofaringe (CECOF) associado ao HPV. Sabe-se que CECOF associado ao HPV apresenta melhor prognóstico do que CECOF não infectado por HPV. Inúmeros estudos em carcinoma cervical demonstram alterações de TLRs, isto provavelmente devido às associações das oncoproteínas E6 e E7 com estes receptores. Em humanos, existem 10 TLRs identificados, os quais colaboram na resposta imune contra bactérias, fungos e vírus, bem como colaboram na promoção ou regressão do tumor. Esta influência do TLR na carcinogênese tem sido alvo de inúmeros estudos devido à ligação entre inflamação e o câncer. O presente trabalho teve como objetivo verificar diferenças na expressão e função de receptores Toll-like em carcinoma espinocelular de orofaringe (CECOF). Para tal, foram utilizados trinta e sete espécimes diagnosticados como CECOF e a expressão imuno-histoquímica das proteínas p16 e TLR4 analisadas. Duas linhagens de CECOF HPV16 + e duas CECOF HPV-. foram utilizadas para análise da expressão de TLR1-10, IL-6 e IL-8, por qPCR. A detecção dos principais TLRs (TLR1, TLR2, TLR6 e TLR4) foi feita por citometria de fluxo. Para ativação da via de sinalização de TLR2, e posterior análise da expressão de IL6 e IL8, as células foram estimuladas com peptidoglicano. Para verificar a expressão e função de TLR4, as células foram estimuladas com LPS e LPS UP para posterior análise de IL-6 e IL-8, por ELISA. Os resultados demonstraram diferenças na expressão gênica de TLR1 e TLR6 entre as linhagens HPV- e o grupo HPV+ e diferenças na expressão proteica de TLR9. TLR2 apresentou aumento da expressão proteica em todas as linhagens e demonstra desencadeamento da resposta imune, com secreção de IL6 e IL8 nas linhagens HPV- (SCC72 e SCC89) e em uma das linhagens HPV+ (SCC2). Interessantemente, TLR4 não apresentou diferenças significativas na expressão gênica e proteica. Entretanto, as linhagens HPV+ não demonstraram resposta pró-inflamatória mesmo quando estimuladas com LPS e LPS ultra puro, agonista específico de TLR4. Assim, este trabalho contribui para estabelecer o perfil da expressão dos receptores Toll-like em linhagens celulares de CECOF HPV- e HPV+, e aponta para alterações ocorridas na via de sinalização mediada por TLR4. Além disso, nossos resultados abrem portas para futuros estudos na avaliação de alterações causadas no sistema imune inato pelo HPV, em carcinomas espinocelulares de orofaringe. / The incidence of HPV- associated oropharynx squamous cell carcinoma (OPSCC) has increased in recent years. HPV- associated OPSCC has a better prognosis than OPSCC not infected with HPV. In cervical carcinoma, HPV oncoproteins E6 and E7 influence the expression of Toll-like receptors (TLR). To date, 10 TLRs have been identified in humans and many are important for the detection of bacteria, fungi and viruses, as well as regression and tumor promotion. This influence of TLR in carcinogenesis has been the subject of numerous studies, due to the connection between inflammation and cancer. This study aimed to determine differences in the expression and function of Toll-like receptor in OPSCC. Thirty-seven tumours were selected and immunohistochemistry for p16 and TLR4 was performed. Two HPV16-associated OPSCC and two OPSCC not associated to HPVcell lines were used. qPCR was performed to analyze the expression of TLR1-10, IL-6 and IL-8. The detection of the main TLRs (TLR1, TLR2, TLR6 and TLR4) was performed by flow cytometry. For activation of the TLR2-signaling pathway and subsequent analysis of IL6 and IL8 expression, cells were stimulated with peptidoglycan. To verify the expression and function TLR4 cells were stimulated with LPS and LPS UP and subsequent analysis of IL-6 and IL-8 by ELISA. The results showed differences in the expression of TLR1 and TLR6 between the HPV- group and the HPV+ group and differences in protein expression of TLR9. TLR2 has increased protein expression in all cell lines and demonstrates the trigger of the immune response, with the secretion of IL6 and IL8 in HPV- cell lines (SCC72 and SCC89) and one HPV+ cell line (SCC2). Interestingly, TLR4 showed no significant differences in gene and protein expression. However, HPV+ cell lines showed no pro-inflammatory response even when stimulated with LPS and LPS UP, a specific agonist of TLR4. This work helps to establish the profile of the expression of Toll-like receptors in OPSCC (SCC72 and SCC89) and HPV- associated OPSCC (SCC2 and SCC90), in vitro, and points to changes in the signaling pathway mediated by TLR4. In addition, our results open new avenues for future studies to assess changes in the innate immune system caused by HPV in oropharynx carcinomas.