Die Wirkung von zwei endogen neuroprotektiven Substanzen, Melatonin und 17 beta-Estradiol wurde an drei Caspase-abhängigen, apoptotischen, aber Exzitotoxin-unabhängigen Schadensmodellen an neuronalen Primärkulturen untersucht und mit der bei vorwiegend nekrotischen Schadensmodellen verglichen. Es zeigten sich eine Abhängigkeit des neuroprotektiven Potentials von der Art des Zelluntergangs sowie unterschiedliche Mechanismen der Neuroprotektion. Melatonin wirkte in allen drei apoptischen Modellen nicht neuroprotektiv, sondern verstärkte die Schädigung der Neurone noch, während partiell gegen die OGD-induzierte Nekrose (OGD, engl. Oxygen glucose deprivation, kombinierter Sauerstoff- und Glukoseentzug) kortikaler Neurone Schutz erzielt wurde. Der Einsatz des endogenen neuroprotektiven Faktors Melatonin als Therapeutikum ist möglicherweise nur bei neurodegenerativen Erkrankungen mit exzitotoxischer Schädigung durch Glutamat oder oxidativem Stress wie bei Epilepsie oder dem Schlaganfall durch Ischämie sinnvoll. Die fehlende bzw. potenzierenden Wirkung von Melatonin bei neuronaler Apoptose in vitro, stellt jedoch einen therapeutischen Erfolg bei der Behandlung der mit apoptotischer Schädigung einhergehenden Alzheimer'schen Erkrankung in Frage. Bei klinischer Anwendung ist auch der von uns erhobene Befund zu beachten, dass in vitro native neuronale Zellen durch Melatonin geschädigt werden. 17 beta-Estradiol wirkte sowohl bei nekrotischer als auch bei apoptotischer Zellschädigung. Dabei zeigten sich wesentliche Unterschiede in den Mechanismen der Neuroprotektion und in der Ansprechbarkeit verschiedener Regionen des Gehirns. Schutz vor Apoptose konnte nur durch eine Langzeitvorbehandlung (20 h) in septalen und hippokampalen Kulturen, nicht jedoch in kortikalen Kulturen beobachtet werden. Dieser Effekt liess sich durch Rezeptorantagonisten, Proteinsynthesehemmung sowie durch Hemmung der Phosphoinositol-3-Kinase blockieren. Eine Kurzzeitbehandlung war gegen Apoptose nicht wirksam, zeigte gegen OGD und Glutamattoxizität jedoch neuroprotektives Potential. Dieser Effekt liess sich nicht antagonisieren, so dass hier ein direkter antioxidativer Mechanismus wahrscheinlich erscheint. Die antiapoptotische Wirkung in septalen und hippokampalen Kulturen korrelierte mit einer höheren Dichte des Estrogenrezeptors-alpha und einer erhöhten Expression antiapoptotischer Proteine in diesen Regionen. Da bei der Alzheimer'schen Erkrankung der Kortex betroffen ist, könnte der fehlende Effekt von 17 beta-Estradiol in kortikalen Neuronen sowohl auf die neuronale Apoptose als auch auf die Proteinexpression von Bcl-2 und Bcl-xL möglicherweise auf experimenteller Basis erklären, warum eine langfristige Estrogentherapie bei Frauen mit milder bis moderater Alzeimer'scher Erkrankung den Progress der Erkrankung nicht aufhalten konnte (Mulnard et al. 2000). / The neuroprotective effect of melatonin and 17 beta-estradiol has been evaluated in several in vitro models of neuronal apoptosis and necrosis. Melatonin was not neuroprotective in three models of apoptosis but showed a pro-apoptotic effect in primary cortical neurons. Melatonin revealed to damage naïve neurons, too. Partial protection was observed against necrotic neurodegeneration after oxygen-glucose deprivation (OGD). The use of melatonin as a therapeutic agent might be of interest in neurodegenerative diseases with excitotoxic damage like epilepsia or ischemia, but is questioned in case of apoptotic neurodegeneration. 17 beta-estradiol was neuroprotectiv in both necrotic and apoptotic neurodegeneration. Differences in the mechanism of neuroprotetion and in the efficacy in different regions of the brain were observed. A neuroprotective effect was visible only in hippocampal and septal cultures if 17 beta-estradiol was applied 20 h prior (long term pre-treatment) but not in cortical neurons. This effect correlates with an increased density of estrogen receptor-alpha and an increased expression of anti-apoptotic proteins like Bcl-2 and Bcl-xL in these regions. These effect could be blocked with receptor antagonists, protein synthesis inhibitors and an inhibitor of the phosphatidylinositol 3-kinase. A short term pre-treatment revealed a receptor independent neuroprotective potential against OGD and glutamate toxicity. The failure of 17 beta-estradiol to protect cortical neurons against apoptosis could be an experimental basis to understand, why a long lasting treatment with estrogens of women with mild to moderate Alzheimer´s disease failed to inhibit the progress of the illness (Mulnard et al., 2000)

La signalisation par l’estrogène a longtemps été considérée comme jouant un rôle critique dans le développement et la progression des cancers hormono-dépendants tel que le cancer du sein. Deux tiers des cancers du sein expriment le récepteur des estrogènes (ER) qui constitue un élément indiscutable dans cette pathologie. L’acquisition d’une résistance endocrinienne est cependant un obstacle majeur au traitement de cette forme de cancer. L’émergence de cancers hormono-indépendants peut est produite par l’activation de ER en absence d’estrogène, l’hypersensibilité du récepteur aux faibles concentrations plasmique d’estrogène ainsi que l’activation de ER par des modulateurs sélectifs. L’activité du ER est fortement influencée par l’environnement cellulaire tel que l’activation de voie de signalisation des facteurs de croissances, la disponibilité de protéines co-régulatrices et des séquences promotrices ciblées. Présentement, les études ont principalement considérées le rôle de ERα, cependant avec la découverte de ERβ, notre compréhension de la diversité des mécanismes potentiels impliquant des réponses ER-dépendantes s’est améliorée. L’activation des voies des kinases par les facteurs de croissance entraîne le développement d’un phénotype tumoral résistant aux traitements actuels. Nos connaissances des voies impliquées dans l’activation de ER sont restreintes. ERα est considéré comme le sous-type dominant et corrèle avec la plupart des facteurs de pronostic dans le cancer du sein. Le rôle de ERβ reste imprécis. Les résultats présentés dans cette thèse ont pour objectif de mieux comprendre l’implication de ERβ dans la prolifération cellulaire par l’étude du comportement de ERβ et ERα suite à l’activation des voies de signalisation par les facteurs de croissance. Nous démontrons que l’activation des récepteurs de surfaces de la famille ErbB, spécifiquement ErbB2/ErbB3, inhibe l’activité transcriptionnelle de ERβ, malgré la présence du coactivateur CBP, tout en activant ERα. De plus, l’inhibition de ERβ est attribuée à un résidu sérine (Ser-255) situé dans la région charnière, absente dans ERα. Des études supplémentaires de ErbB2/ErbB3 ont révélé qu’ils activent la voie PI3K/Akt ciblant à son tour la Ser-255. En effet, cette phosphorylation de ERβ par PI3K/Akt induit une augmentation de l’ubiquitination du récepteur qui promeut sa dégradation par le système ubiquitine-protéasome. Cette dégradation est spécifique pour ERβ. De façon intéressante, la dégradation par le protéasome requiert la présence du coactivateur CBP normalement requis pour l’activité transcriptionnelle des récepteurs nucléaires. Malgré le fait que l’activation de la voie PI3K/Akt corrèle avec une diminution de l’expression des gènes sous le contrôle de ERβ, on observe une augmentation de la prolifération des cellules cancéreuses. L’inhibition de la dégradation de ERβ réduit cette prolifération excessive causée par le traitement avec Hrgβ1, un ligand de ErbB3. Un nombre croissant d’évidences indique que les voies de signalisations des facteurs de croissance peuvent sélectivement réguler l’activité transcriptionnelle de sous-types de ER. De plus, le ratio ERα/ERβ dans les cancers du sein devient un outil de diagnostique populaire afin de déterminer la sévérité d’une tumeur. En conclusion, la caractérisation moléculaire du couplage entre la signalisation des facteurs de croissance et la fonction des ERs permettra le développement de nouveaux traitements afin de limiter l’apparition de cellules tumorales résistantes aux thérapies endocriniennes actuelles. / It has long been appreciated that estrogenic signaling plays a critical role in the development of hormone-dependent cancers such as breast cancer. Two-thirds of breast cancers express estrogen receptor (ER) which has been demonstrated to play an irrefutable role in tumour development and progression. However the acquisition of endocrine resistance has become a major obstacle in the treatment of hormone-dependent cancers that have acquired a hormone-independent state. Hormone-independent cancers emerge from an array of pathways involving ER activation in the absence of estrogen, hypersensitivity of ER to low serum levels of estrogen and activation by estrogen antagonists. The activity of ER is critically influenced by the cellular environment such as growth factor signaling pathways, availability of coregulatory proteins and the promoter sequence of target genes. The mechanisms studied have mostly considered the role of ERα, however with the discovery of the second subtype, ERβ, the understanding on the diversity of potential mechanisms involving ER-dependent responses have improved. Hormonal-independent activation of ER can occur in estrogen-dependent breast tumours, with concomitant rise in kinase signaling pathways, resulting in the acquisition of a therapeutic resistant phenotype in treated women. Our knowledge is relatively limited on which pathways trigger ER signaling and how these phosphorylation-coupled events affect ER activity. ERα is considered the dominant subtype and correlates with most of the prognostic factors in breast cancers. Conversely the role of ERβ remains unclear. The results presented in this thesis were carried out with the objective of gaining a better understanding of ERβ’s role in cellular proliferation by examining the behavior of ERβ and ERα during the activation of growth factor signaling pathways by cell-surface receptor-tyrosine kinases. We demonstrate here that the activation of cell surface receptors of the ErbB family, specifically ErbB2/ErbB3, inhibits the transcriptional activity of ERβ despite the presence of the coactivator CBP, yet activated ERα. Furthermore the inhibition of ERβ was attributed to a specific serine residue located within the hinge region, not present in ERα. Additional studies of ErbB2/ErbB3-initiated signaling revealed that it triggered the activation of the PI3K/Akt pathway which targeted the serine residue within the hinge region of ERβ. In fact, phosphorylation of ERβ by the PI3K/Akt pathway led to an increase in receptor ubiquitination which promoted its degradation by the ubiquitin-proteasome system which was subtype specific. Interestingly, proteasomal degradation required the presence of the coactivator CBP, which is normally involved in assisting nuclear receptor transcriptional activity. Although the activation of the PI3K/Akt pathway correlated with a decrease in the expression of ERβ target genes it led to an increase in the proliferation of breast cancer cells. Inhibiting the degradation of ERβ reduced the enhanced proliferation of breast cancer cells brought about by the treatment of ErbB3’s ligand, Hrgβ1. Increasing evidence indicates that growth factor signaling pathways can selectively regulate the transcriptional activity of ER subtypes, and the ratio of ERα/ERβ expression in breast tumours is becoming a popular prognostic factor to evaluate the severity of the tumour. Therefore the molecular characterization of the coupling between growth factor signaling and ER function should provide improved therapeutical approaches to overcome or delay the onset of resistance to endocrine therapy in hormone-dependent cancers.

No description available.

O epitélio nasal é a primeira porção do sistema respiratório a entrar em contato com o ambiente externo. Partículas da poluição do ar, principalmente os compostos orgânicos absorvidos, podem atuar como liberadores endócrinos. O receptor aril hidrocarboneto (AhR) é um importante competidor dos receptores de estrógeno-beta (ERbeta) que regulam a transcrição do gene para enzimas de metabolização xenobióticas (enzimas do citocromo P450). O objetivo deste estudo é identificar e quantificar ERbeta, AhR, CYP1A1, CYP1A2, CYP1B1 e o perfil de muco no epitélio nasal de camundongos machos e fêmeas em diferentes fases do ciclo estral. Camundongos BALB/c machos (n=32) e fêmeas (n=84) foram expostos ao ar ambiente e ao MP2,5 concentrado a 600 ug.m-³ em um concentrador de partículas ambientais (CPAs). As fêmeas foram divididas de acordo com as fases do ciclo estral: proestro, estro e diestro. O epitélio nasal foi avaliado por RT-PCR e imuno-histoquímica para análise de expressão de ERbeta (proteína), Erbeta-1 e Erbeta-2 (gene), AhR (proteína e gene) e Cyp1a1, Cyp1a2 and Cyp1b1 (gene). A quantificação de muco neutro - Periodic Acid Schiff\'s (PAS+) e ácido - Alcian Blue (AB+) foi avaliada por morfometria. As exposições foram realizadas durante 5 dias/semana, por 45 ± 55 dias. A expressão de Erbeta-2 RNAm apresentou diferenças em resposta à exposição ao CPAs (p=0,016), bem como uma diminuição em fêmeas, quando comparadas aos camundongos machos (p=0,036). A expressão de Cyp1b1 RNAm foi significantemente menor no grupo exposto ao CPAs, em relação ao grupo exposto ao ar ambiente nas fêmeas em diestro (p=0,036). A expressão de Erbeta foi aumentada no epitélio nasal de fêmeas em estro expostas ao CPAs (p=0,005) e a expressão de AhR foi menor em fêmeas em proestro expostas ao CPAs (p=0,048). A exposição ao CPAs levou ao aumento do conteúdo de muco ácido em camundongos machos (p=0,048), o qual diminuiu em fêmeas (p=0,040), quando comparados ao grupo ar ambiente. Este estudo mostrou que houve diferentes respostas à exposição à poluição do ar no epitélio nasal entre machos e fêmeas, e que essas diferenças podem estar relacionadas com a predisposição de fêmeas apresentarem maior suscetibilidade a doenças respiratórias das vias aéreas / The nasal epithelium is the first portion of the respiratory system to reach contact with the external environment. Air pollution particles, mainly the organic compounds absorbed into them, may act as endocrine releasers. The aryl hydrocarbon (AhR) receptor is an important competitor of estrogenic receptors-beta (ERbeta) that regulate transcription of gene coding for xenobiotic-metabolizing enzymes (cytochrome P450 enzymes). The aim of this study is to identify and quantify in the nasal epithelium of male and female mice in different estrous cycle phases related with ERbeta, AhR, CYP1A1, 1A2, 1B1 and the mucus profile. Male (n=32) and female (n=84) BALB/c mice were exposed to ambient air and PM2.5 concentrated at 600 ug.m-³ in an ambient particle concentrator with a particulate matter diameter of 2.5 um (PM2.5). Females were subdivided in three estrous cycles: proestrus, estrus and diestrus. Nasal epithelium was evaluated through RT-PCR and immunohistochemistry for the expression of ERbeta (protein), Erbeta-1 and Erbeta-2 (gene expression), AhR (protein and gene expression) and Cyp1a1, Cyp1a2 and Cyp1b1 (gene expression). Morphometry was applied for evaluation of mucus profile: acid - Alcian Blue (AB+) and neutral - Periodic Acid Schiff\'s (PAS+). Exposure happened for 5 days/week, for 45 ± 55 days. There were differences in Erbeta-2 mRNA in response to exposition to CPAs (p=0.016), and a significant decrease in female compared male mice (p=0.036). Cyp1b1 mRNA was significantly smaller in the CPAs-exposed group compared with the ambient air group in diestrus female mice (p=0.036). The ERbeta expression increased in the nasal epithelium of CPAs-exposed females in the estrus cycle (p=0.005), and the AhR expression decreased in the proestrus cycle of CPAs-exposed females (p=0.048). The exposure to the CPAs led to an increase in the acidic content of mucus in male mice (p=0.048), and decreased in female mice (p=0.040), compared to the ambient air group. This study showed there were different responses in the nasal epithelia of male and female mice exposed to air pollution, which could be related to the predisposition of the females to present more susceptibility to airway respiratory diseases

O câncer de mama é a principal causa de mortalidade por câncer entre as mulheres. Alguns biomarcadores e características clínicas são utilizados para avaliar o prognóstico e prever a resposta a uma série de abordagens terapêuticas. A Homocisteína é conhecida como um fator de risco para doença vascular aterosclerótica, mas sua participação na biologia do câncer ainda é incerta. Cisteína é o aminoácido sulfurado derivado da Homocisteína no ciclo da Metionina. Este ciclo metabólico origina as bases nitrogenadas e também determina o nível de metilação da molécula de DNA. É atualmente reconhecido que a hipometilação global do genoma é um evento chave na transformação maligna das células. O objetivo deste estudo foi avaliar os níveis séricos de homocisteína e cisteína como biomarcadores de sobrevida e de progressão da doença em câncer de mama. Também foi avaliado o efeito de um curso de curta duração (um mês) de tratamento hormonal sobre os níveis de Homocisteína, Cisteína e metilação do DNA. Amostras de sangue foram obtidos por ocasião da biópsia inicial (pré-tratamento) em todas as pacientes e, de tumor e de tecido normal adjacente, ao diagnóstico eem um mês após, para as pacientes que receberam o regime hormonal neo-adjuvante (pré-operatório). Todas as pacientes eram mulheres na pós-menopausa, com tumores de mama ressecáveis, acompanhadas em dois hospitais públicos, que consentiram em participar de outros dois protocolos de pesquisa prévios. Homocisteína e Cisteína foram analisadas por HPLC e a metilação global do DNA do tecido foi determinada por meio da técnica de MSRE (Methylation-Sensitive Restriction Enzyme). Foi observada uma diferença significativa entre os níveis pré e póstratamento de Homocisteína e Cisteína em tumores avançados, sugerindo um papel prognóstico em pacientes com características clínicas reservadas. As variações nos níveis de Homocisteína se mostraram significativamente correlacionadas com a sobrevida livre de doença. O modelo de risco proporcional de Cox demonstrou que os níveis de homocisteína e o status dos linfonodos representaram fatores prognósticos independentes em termos de sobrevida livre de doença. Embora mais estudos sejam necessários para confirmar estes resultados, nossa pesquisa sugere que a Homocisteína pode ser usada como um biomarcador de prognóstico para câncer de mama / Breast cancer is the leading cause of cancer mortality among women. Some biomarkers and clinical features are used to evaluate prognosis and to predict response to a range of therapeutic approaches. Homocysteine is well known as a risk factor in atherosclerotic vascular diseases, but its participation in cancer biology is still unclear. Cysteine is a sulfur amino acid derived from Homocysteine in the Methionine cycle. This metabolic cycle originates the nitrogenous bases and determines the methylation level of the DNA molecule as well. It is currently recognized that the global hipomethylation of the genome is a key event in the malign transformation of cells. The aim of this study was to evaluate serum Homocysteine and Cysteine as biomarkers of survival and disease progression in breast tumor, as well as the methylation status of tumor and normal tissues. The effect of a short course (one month) of hormonal treatment on Homocysteine, Cysteine and DNA methylation levels was also evaluated. Blood samples were collected during the initial biopsy (pretreatment) in all patients and, tumor samples and normal adjacent tissue, at diagnosis and one month after, for the patients that received neo-adjuvant hormonal regimen (pre-treatment). All patients were post-menopausal women, with resectable breast tumors, followed at two public hospitals, and that had consented to participate in two previous research protocols related to their disease. Serum Homocysteine and Cysteine were analyzed by HPLC and tissue global DNA methylation was determined by the MSRE (Methylation- Sensitive Restriction Enzyme) technique. A significant difference was observed between pre- and post-treatment levels of Homocysteine and Cysteine in advanced tumors, suggesting a prognostic role in patients with poor clinical characteristics. Variations in Homocysteine levels were significantly correlated with disease free survival. Cox proportional risk model demonstrated that nodal status and Homocysteine levels were independent prognostic factors for Disease Free Survival. Although more studies are needed to confirm these results, our research suggests that Homocysteine might be used as a prognostic biomarker for breast cancer

No description available.

La signalisation par l’estrogène a longtemps été considérée comme jouant un rôle critique dans le développement et la progression des cancers hormono-dépendants tel que le cancer du sein. Deux tiers des cancers du sein expriment le récepteur des estrogènes (ER) qui constitue un élément indiscutable dans cette pathologie. L’acquisition d’une résistance endocrinienne est cependant un obstacle majeur au traitement de cette forme de cancer. L’émergence de cancers hormono-indépendants peut est produite par l’activation de ER en absence d’estrogène, l’hypersensibilité du récepteur aux faibles concentrations plasmique d’estrogène ainsi que l’activation de ER par des modulateurs sélectifs. L’activité du ER est fortement influencée par l’environnement cellulaire tel que l’activation de voie de signalisation des facteurs de croissances, la disponibilité de protéines co-régulatrices et des séquences promotrices ciblées. Présentement, les études ont principalement considérées le rôle de ERα, cependant avec la découverte de ERβ, notre compréhension de la diversité des mécanismes potentiels impliquant des réponses ER-dépendantes s’est améliorée. L’activation des voies des kinases par les facteurs de croissance entraîne le développement d’un phénotype tumoral résistant aux traitements actuels. Nos connaissances des voies impliquées dans l’activation de ER sont restreintes. ERα est considéré comme le sous-type dominant et corrèle avec la plupart des facteurs de pronostic dans le cancer du sein. Le rôle de ERβ reste imprécis. Les résultats présentés dans cette thèse ont pour objectif de mieux comprendre l’implication de ERβ dans la prolifération cellulaire par l’étude du comportement de ERβ et ERα suite à l’activation des voies de signalisation par les facteurs de croissance. Nous démontrons que l’activation des récepteurs de surfaces de la famille ErbB, spécifiquement ErbB2/ErbB3, inhibe l’activité transcriptionnelle de ERβ, malgré la présence du coactivateur CBP, tout en activant ERα. De plus, l’inhibition de ERβ est attribuée à un résidu sérine (Ser-255) situé dans la région charnière, absente dans ERα. Des études supplémentaires de ErbB2/ErbB3 ont révélé qu’ils activent la voie PI3K/Akt ciblant à son tour la Ser-255. En effet, cette phosphorylation de ERβ par PI3K/Akt induit une augmentation de l’ubiquitination du récepteur qui promeut sa dégradation par le système ubiquitine-protéasome. Cette dégradation est spécifique pour ERβ. De façon intéressante, la dégradation par le protéasome requiert la présence du coactivateur CBP normalement requis pour l’activité transcriptionnelle des récepteurs nucléaires. Malgré le fait que l’activation de la voie PI3K/Akt corrèle avec une diminution de l’expression des gènes sous le contrôle de ERβ, on observe une augmentation de la prolifération des cellules cancéreuses. L’inhibition de la dégradation de ERβ réduit cette prolifération excessive causée par le traitement avec Hrgβ1, un ligand de ErbB3. Un nombre croissant d’évidences indique que les voies de signalisations des facteurs de croissance peuvent sélectivement réguler l’activité transcriptionnelle de sous-types de ER. De plus, le ratio ERα/ERβ dans les cancers du sein devient un outil de diagnostique populaire afin de déterminer la sévérité d’une tumeur. En conclusion, la caractérisation moléculaire du couplage entre la signalisation des facteurs de croissance et la fonction des ERs permettra le développement de nouveaux traitements afin de limiter l’apparition de cellules tumorales résistantes aux thérapies endocriniennes actuelles. / It has long been appreciated that estrogenic signaling plays a critical role in the development of hormone-dependent cancers such as breast cancer. Two-thirds of breast cancers express estrogen receptor (ER) which has been demonstrated to play an irrefutable role in tumour development and progression. However the acquisition of endocrine resistance has become a major obstacle in the treatment of hormone-dependent cancers that have acquired a hormone-independent state. Hormone-independent cancers emerge from an array of pathways involving ER activation in the absence of estrogen, hypersensitivity of ER to low serum levels of estrogen and activation by estrogen antagonists. The activity of ER is critically influenced by the cellular environment such as growth factor signaling pathways, availability of coregulatory proteins and the promoter sequence of target genes. The mechanisms studied have mostly considered the role of ERα, however with the discovery of the second subtype, ERβ, the understanding on the diversity of potential mechanisms involving ER-dependent responses have improved. Hormonal-independent activation of ER can occur in estrogen-dependent breast tumours, with concomitant rise in kinase signaling pathways, resulting in the acquisition of a therapeutic resistant phenotype in treated women. Our knowledge is relatively limited on which pathways trigger ER signaling and how these phosphorylation-coupled events affect ER activity. ERα is considered the dominant subtype and correlates with most of the prognostic factors in breast cancers. Conversely the role of ERβ remains unclear. The results presented in this thesis were carried out with the objective of gaining a better understanding of ERβ’s role in cellular proliferation by examining the behavior of ERβ and ERα during the activation of growth factor signaling pathways by cell-surface receptor-tyrosine kinases. We demonstrate here that the activation of cell surface receptors of the ErbB family, specifically ErbB2/ErbB3, inhibits the transcriptional activity of ERβ despite the presence of the coactivator CBP, yet activated ERα. Furthermore the inhibition of ERβ was attributed to a specific serine residue located within the hinge region, not present in ERα. Additional studies of ErbB2/ErbB3-initiated signaling revealed that it triggered the activation of the PI3K/Akt pathway which targeted the serine residue within the hinge region of ERβ. In fact, phosphorylation of ERβ by the PI3K/Akt pathway led to an increase in receptor ubiquitination which promoted its degradation by the ubiquitin-proteasome system which was subtype specific. Interestingly, proteasomal degradation required the presence of the coactivator CBP, which is normally involved in assisting nuclear receptor transcriptional activity. Although the activation of the PI3K/Akt pathway correlated with a decrease in the expression of ERβ target genes it led to an increase in the proliferation of breast cancer cells. Inhibiting the degradation of ERβ reduced the enhanced proliferation of breast cancer cells brought about by the treatment of ErbB3’s ligand, Hrgβ1. Increasing evidence indicates that growth factor signaling pathways can selectively regulate the transcriptional activity of ER subtypes, and the ratio of ERα/ERβ expression in breast tumours is becoming a popular prognostic factor to evaluate the severity of the tumour. Therefore the molecular characterization of the coupling between growth factor signaling and ER function should provide improved therapeutical approaches to overcome or delay the onset of resistance to endocrine therapy in hormone-dependent cancers.

O epitélio nasal é a primeira porção do sistema respiratório a entrar em contato com o ambiente externo. Partículas da poluição do ar, principalmente os compostos orgânicos absorvidos, podem atuar como liberadores endócrinos. O receptor aril hidrocarboneto (AhR) é um importante competidor dos receptores de estrógeno-beta (ERbeta) que regulam a transcrição do gene para enzimas de metabolização xenobióticas (enzimas do citocromo P450). O objetivo deste estudo é identificar e quantificar ERbeta, AhR, CYP1A1, CYP1A2, CYP1B1 e o perfil de muco no epitélio nasal de camundongos machos e fêmeas em diferentes fases do ciclo estral. Camundongos BALB/c machos (n=32) e fêmeas (n=84) foram expostos ao ar ambiente e ao MP2,5 concentrado a 600 ug.m-³ em um concentrador de partículas ambientais (CPAs). As fêmeas foram divididas de acordo com as fases do ciclo estral: proestro, estro e diestro. O epitélio nasal foi avaliado por RT-PCR e imuno-histoquímica para análise de expressão de ERbeta (proteína), Erbeta-1 e Erbeta-2 (gene), AhR (proteína e gene) e Cyp1a1, Cyp1a2 and Cyp1b1 (gene). A quantificação de muco neutro - Periodic Acid Schiff\'s (PAS+) e ácido - Alcian Blue (AB+) foi avaliada por morfometria. As exposições foram realizadas durante 5 dias/semana, por 45 ± 55 dias. A expressão de Erbeta-2 RNAm apresentou diferenças em resposta à exposição ao CPAs (p=0,016), bem como uma diminuição em fêmeas, quando comparadas aos camundongos machos (p=0,036). A expressão de Cyp1b1 RNAm foi significantemente menor no grupo exposto ao CPAs, em relação ao grupo exposto ao ar ambiente nas fêmeas em diestro (p=0,036). A expressão de Erbeta foi aumentada no epitélio nasal de fêmeas em estro expostas ao CPAs (p=0,005) e a expressão de AhR foi menor em fêmeas em proestro expostas ao CPAs (p=0,048). A exposição ao CPAs levou ao aumento do conteúdo de muco ácido em camundongos machos (p=0,048), o qual diminuiu em fêmeas (p=0,040), quando comparados ao grupo ar ambiente. Este estudo mostrou que houve diferentes respostas à exposição à poluição do ar no epitélio nasal entre machos e fêmeas, e que essas diferenças podem estar relacionadas com a predisposição de fêmeas apresentarem maior suscetibilidade a doenças respiratórias das vias aéreas / The nasal epithelium is the first portion of the respiratory system to reach contact with the external environment. Air pollution particles, mainly the organic compounds absorbed into them, may act as endocrine releasers. The aryl hydrocarbon (AhR) receptor is an important competitor of estrogenic receptors-beta (ERbeta) that regulate transcription of gene coding for xenobiotic-metabolizing enzymes (cytochrome P450 enzymes). The aim of this study is to identify and quantify in the nasal epithelium of male and female mice in different estrous cycle phases related with ERbeta, AhR, CYP1A1, 1A2, 1B1 and the mucus profile. Male (n=32) and female (n=84) BALB/c mice were exposed to ambient air and PM2.5 concentrated at 600 ug.m-³ in an ambient particle concentrator with a particulate matter diameter of 2.5 um (PM2.5). Females were subdivided in three estrous cycles: proestrus, estrus and diestrus. Nasal epithelium was evaluated through RT-PCR and immunohistochemistry for the expression of ERbeta (protein), Erbeta-1 and Erbeta-2 (gene expression), AhR (protein and gene expression) and Cyp1a1, Cyp1a2 and Cyp1b1 (gene expression). Morphometry was applied for evaluation of mucus profile: acid - Alcian Blue (AB+) and neutral - Periodic Acid Schiff\'s (PAS+). Exposure happened for 5 days/week, for 45 ± 55 days. There were differences in Erbeta-2 mRNA in response to exposition to CPAs (p=0.016), and a significant decrease in female compared male mice (p=0.036). Cyp1b1 mRNA was significantly smaller in the CPAs-exposed group compared with the ambient air group in diestrus female mice (p=0.036). The ERbeta expression increased in the nasal epithelium of CPAs-exposed females in the estrus cycle (p=0.005), and the AhR expression decreased in the proestrus cycle of CPAs-exposed females (p=0.048). The exposure to the CPAs led to an increase in the acidic content of mucus in male mice (p=0.048), and decreased in female mice (p=0.040), compared to the ambient air group. This study showed there were different responses in the nasal epithelia of male and female mice exposed to air pollution, which could be related to the predisposition of the females to present more susceptibility to airway respiratory diseases

O câncer de mama é a principal causa de mortalidade por câncer entre as mulheres. Alguns biomarcadores e características clínicas são utilizados para avaliar o prognóstico e prever a resposta a uma série de abordagens terapêuticas. A Homocisteína é conhecida como um fator de risco para doença vascular aterosclerótica, mas sua participação na biologia do câncer ainda é incerta. Cisteína é o aminoácido sulfurado derivado da Homocisteína no ciclo da Metionina. Este ciclo metabólico origina as bases nitrogenadas e também determina o nível de metilação da molécula de DNA. É atualmente reconhecido que a hipometilação global do genoma é um evento chave na transformação maligna das células. O objetivo deste estudo foi avaliar os níveis séricos de homocisteína e cisteína como biomarcadores de sobrevida e de progressão da doença em câncer de mama. Também foi avaliado o efeito de um curso de curta duração (um mês) de tratamento hormonal sobre os níveis de Homocisteína, Cisteína e metilação do DNA. Amostras de sangue foram obtidos por ocasião da biópsia inicial (pré-tratamento) em todas as pacientes e, de tumor e de tecido normal adjacente, ao diagnóstico eem um mês após, para as pacientes que receberam o regime hormonal neo-adjuvante (pré-operatório). Todas as pacientes eram mulheres na pós-menopausa, com tumores de mama ressecáveis, acompanhadas em dois hospitais públicos, que consentiram em participar de outros dois protocolos de pesquisa prévios. Homocisteína e Cisteína foram analisadas por HPLC e a metilação global do DNA do tecido foi determinada por meio da técnica de MSRE (Methylation-Sensitive Restriction Enzyme). Foi observada uma diferença significativa entre os níveis pré e póstratamento de Homocisteína e Cisteína em tumores avançados, sugerindo um papel prognóstico em pacientes com características clínicas reservadas. As variações nos níveis de Homocisteína se mostraram significativamente correlacionadas com a sobrevida livre de doença. O modelo de risco proporcional de Cox demonstrou que os níveis de homocisteína e o status dos linfonodos representaram fatores prognósticos independentes em termos de sobrevida livre de doença. Embora mais estudos sejam necessários para confirmar estes resultados, nossa pesquisa sugere que a Homocisteína pode ser usada como um biomarcador de prognóstico para câncer de mama / Breast cancer is the leading cause of cancer mortality among women. Some biomarkers and clinical features are used to evaluate prognosis and to predict response to a range of therapeutic approaches. Homocysteine is well known as a risk factor in atherosclerotic vascular diseases, but its participation in cancer biology is still unclear. Cysteine is a sulfur amino acid derived from Homocysteine in the Methionine cycle. This metabolic cycle originates the nitrogenous bases and determines the methylation level of the DNA molecule as well. It is currently recognized that the global hipomethylation of the genome is a key event in the malign transformation of cells. The aim of this study was to evaluate serum Homocysteine and Cysteine as biomarkers of survival and disease progression in breast tumor, as well as the methylation status of tumor and normal tissues. The effect of a short course (one month) of hormonal treatment on Homocysteine, Cysteine and DNA methylation levels was also evaluated. Blood samples were collected during the initial biopsy (pretreatment) in all patients and, tumor samples and normal adjacent tissue, at diagnosis and one month after, for the patients that received neo-adjuvant hormonal regimen (pre-treatment). All patients were post-menopausal women, with resectable breast tumors, followed at two public hospitals, and that had consented to participate in two previous research protocols related to their disease. Serum Homocysteine and Cysteine were analyzed by HPLC and tissue global DNA methylation was determined by the MSRE (Methylation- Sensitive Restriction Enzyme) technique. A significant difference was observed between pre- and post-treatment levels of Homocysteine and Cysteine in advanced tumors, suggesting a prognostic role in patients with poor clinical characteristics. Variations in Homocysteine levels were significantly correlated with disease free survival. Cox proportional risk model demonstrated that nodal status and Homocysteine levels were independent prognostic factors for Disease Free Survival. Although more studies are needed to confirm these results, our research suggests that Homocysteine might be used as a prognostic biomarker for breast cancer

I hjärnan finns neuron och gliaceller. Förut trodde man att neuroner var dem enda som hade en viktig funktion i hjärnan men på senare tid har upptäckt att gliaceller har en större betydande roll än man tidigare trott. Gliaceller är ett samlingsnamn som innefattar bland annat microglia celler, oligodendrocyter och astrocyter. Östrogen är ett steroidhormon som har många viktiga funktioner i kroppen som bland annat reproduktionen, immunförsvaret, skelettet och endokrina system. Östrogen binder till östrogenreceptorer och de finns 3 stycken olika som kallas för östrogenreceptor alfa (α), östrogenreceptor beta (β) och G-proteinkopplade östrogenreceptor (GRP30). Alla dessa östrogenreceptorer har man funnit i hjärnan. Syftet med detta projektarbete är att ge en djupare förståelse om östrogens signalering i hjärnans gliaceller och om östrogens signalering kan ge någon relevant funktion till framtida farmakologiska behandlingar.  Systematisk litteraturstudie gjordes och sökningar på databasen PubMed. Begränsade antalet träffar med sökord, inklusionskriterier och exklusionskriterier. Artiklar granskades sedan via ett urvalssystem och relevanta artiklar användes för att besvara syfte och frågeställningar.  Östrogensignaleringen på gliaceller har många olika effekter. En signalering på östrogenreceptor β på oligodendrocyter leder till mognad, differentiering, bättre överlevd och att remyeliniseringen aktiverades. Medan en östrogens signalering på microglia cellens östrogenreceptorer α, β och GRP30 leder dämpning av inflammation och förbättrad kognitiv funktion. Östrogensignaleringen på astrocyter ger flera olika effekter såsom metabolismen av glukos, progesteron syntesen, glutamattransportören GLT-1, tillväxtfaktorn TGF-α, upptaget av glutamat samt ökad proteinproduktion av AMPA-receptor. Den nya kunskapen om östrogens signalering på hjärnans gliaceller kan leda till framtida farmakologiska behandlingar vid hjärnskada och ischemisk stroke. Östrogenet har visat på neuronskyddande effekter via signalering på gliaceller. Svagheten är att de endast är djurstudier som ligger till grund för kunskapen om östrogens signalering på gliaceller. I framtiden skulle det behövas styrkas med studier gjorda på människa. En styrka är att djurstudierna ger en fingervisning om östrogen signaleringen eftersom hjärnans uppbyggnad är likvärdig.