Orientador: Ljubica Tasic / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-20T16:55:17Z (GMT). No. of bitstreams: 1 Prando_Alessandra_D.pdf: 9977861 bytes, checksum: 15d25bce7d95433f95b938e68fdeaac8 (MD5) Previous issue date: 2012 / Resumo: Até o momento, pouco se sabe sobre os mecanismos de virulência da bactéria Xanthomonas axonopodis pv. citri (XAC), agente causador do cancro cítrico. Acredita-se que chaperonas de secreção (CS) estão envolvidas no processo de patogenicidade de XAC primeiramente formando complexos com fatores de virulência e auxiliando no encaminhamento desses para os sistemas de secreção utilizando o ATP como fonte de energia. Neste trabalho foram adquiridos dados de fluorescência de emissão, dicroísmo circular, desenovelamento térmico e de ressonância magnética nuclear de H NMR e de 2D {N,H} HSQC de duas proteínas da XAC, a XAC1990 (FlgN) e XACb0033. Para ambas proteínas foram propostas estruturas 3D usando a análise de footprinting com restrições SASA e rmsd. Para as estruturas propostas foi verificado que os dados de fluorescência corroboram com a estrutura 3D não ocorrendo o mesmo para os dados de CD e NMR que revelaram baixo conteúdo helicoidal além de ausência de estrutura 3 D. A interação da proteína FlgN com a sua proteína parceira FlgK também foi sugerida através das análises de CD e fluorescência. Na segunda parte do trabalho foram estudadas as interações entre a proteína Hsp90 da laranja com diferentes ligantes aplicando a técnica de Saturation Transfer Difference (STD-NMR) e espectroscopia de fluorescência. Estas análises revelaram dados que corroboraram com o modelo proposto e, além disso, indicaram que os hidrogênios H-8 e H-2 da adenina e H-1'da ribose estão localizados no sítio ligante da proteína com os fosfatos orientados para fora. Através da fluorescência foram calculados os valores de Kd e foi verificado que a geldanamicina é um potente inibidor de Hsp90 da laranja / Abstract: So far, the Xanthomonas axonopodis pv. citri (XAC) mechanisms of bacterial virulence is unknown. It is believed that secretion chaperones (CS) are involved in the XAC's virulence process by first forming complexes with virulence factors, and assisting in their presentation to corresponding secretion systems using ATP as a source of energy. Fluorescence emission, circular dichroism, thermal unfolding and nuclear magnetic resonance NMR H and 2D {N,H} HSQC data from two proteins of XAC, XAC1990 (FlgN) and XACb0033 were collected. For both proteins, 3D structures were proposed using the footprinting analysis with RMSD and SASA restrictions. For the proposed structures were verified which the fluorescence data were consistent with the 3D structure. The CD and NMR data revealed low-helical content and absence of 3D structure. The interaction of the protein FlgN with its partner, FlgK, was suggested by CD and fluorescence analysis. In the second part, the interactions between the orange's Hsp90 protein with different ligants using Saturation Transfer Difference (STD-NMR) and fluorescence spectroscopy techniques were studied. These analyzes revealed which the data were consistent with the proposed model and moreover showed that the adenine's hydrogens H-8 and H-2 and ribose's hydrogen H-1'are located in the protein binding site with the phosphate driven out. By fluorescence values were calculed Kd and it was verified that geldanamycin is a potent inhibitor of orange's Hsp90 / Doutorado / Quimica Organica / Doutor em Ciências

Orientador: Carlos Henrique Inácio Ramos / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-22T11:29:26Z (GMT). No. of bitstreams: 1 Silva_VivianeCristinaHeinzenda_D.pdf: 5558657 bytes, checksum: 719a2c54c3d42be8642a0beb9014221c (MD5) Previous issue date: 2013 / Resumo: As chaperonas moleculares estão envolvidas na manutenção da homeostase celular, auxiliando no correto enovelamento de proteínas, e consequentemente em sua funcionalidade. Duas famílias de chaperonas moleculares participam de pontos-chave neste sistema. Uma delas é a Hsp100 que tem papel importante na desagregação de proteínas; a outra é a Hsp90 que tem o papel de auxiliar no enovelamento, ativação, e na translocação de proteínas regulatórias e sinalizadoras. Neste trabalho foram caracterizadas as chaperonas Hsp100 e Hsp90 de cana-de-açúcar, denominadas SHsp101 e SsHsp90, respectivamente, cuja expressão em níveis basais foi detectada em tecido foliar. As proteínas recombinantes foram produzidas em Escherichia coli, de maneira solúvel, e após purificação apresentaram-se enoveladas. A SHsp101 foi obtida como um hexâmero em solução, apresentando capacidade de ligar nucleotídeos ATP e ADP, e de hidrolisar o ATP de maneira alostérica com cooperatividade positiva; mas não foi capaz de hidrolisar o ADP, que por sua vez mostrou-se inibidor da atividade ATPásica. A SHsp101 exibiu atividades de proteção do substrato luciferase contra agregação induzida por alta temperatura e de desagregação e reenovelamento da proteína-modelo GFPuv, na presença de ATP e ATP?S. Análises de complementação in vivo revelaram que a superexpressão heteróloga de SHsp101 em cepas de levedura mutantes nulo de hsp104, aumentou a termotolerância a 53°C, proporcionando um aumento de 80 vezes na sobrevivência das leveduras. A SsHsp90 apresentou-se dimérica em solução, com características estruturais e conformacionais (modelo tridimensional gerado por modelagem comparativa e validado por meio de análises de ligação cruzada acoplada à espectometria de massas) semelhantes às homólogas de outros organismos. A SsHsp90 apresentou atividade chaperona de proteção contra agregação da proteína-modelo citrato sintase desnaturada por choque térmico. As informações acerca da expressão, estrutura, e função de SHsp101 e SsHsp90 obtidas neste trabalho, contribuem para um melhor entendimento destas famílias de chaperonas moleculares, particularmente em plantas, que por serem organismos sésseis, estão mais expostos às condições adversas do ambiente / Abstract: Molecular chaperones are involved in the maintenance of cellular homeostasis by promoting the correct folding of proteins, and consequently, ensuring their functionality. Two families of molecular chaperones participate at key points in this system. The first is Hsp90, which assists in protein refolding, activation, and the trafficking of regulatory and signaling proteins, while the second is Hsp100, which has an important role in protein disaggregation. In this study, the Hsp90 and Hsp100 proteins from sugarcane were characterized, denoted as SsHsp90 and SHsp101, respectively, and their basal level of expression was detected in leaf tissue. In addition, both were produced by Escherichia coli as soluble form and then they were purified in a folded state. The SHsp101 was obtained folded as hexamer in solution and showed capacity of bind both ATP and ADP, but could only hydrolyze ATP in an allosteric manner with positive cooperativity. In fact, the presence of ADP had an inhibitory effect on the ATPase activity. SHsp101 exhibited protection against aggregation of luciferase, and showed a disaggregation and refolding activity of GFPuv in the presence ATP and ATP?S. In vivo complementation analysis revealed that heterologous overexpression of SHsp101 in a null hsp104 yeast strain correlated with an 80 fold increase in yeast survival at 53°C. The dimer obtained for SsHsp90 had similar structural and conformational characteristics compared to other Hsp90 homologues, and was compatible with a three-dimensional model generated by comparative modeling, which was validated by cross-linking coupled to mass spectrometry. The SsHsp90 protected against thermal aggregation of citrate synthase. Taken together, the information about the expression, structure, and function of SHsp101 and SsHsp90 obtained in this study contribute to a better understanding of these molecular chaperone protein families, particularly in plants, which are sessile organisms and more exposed to adverse environmental conditions / Doutorado / Bioquimica / Doutora em Biologia Funcional e Molecular

Orientador: José Andrés Yunes / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-24T08:28:04Z (GMT). No. of bitstreams: 1 Milani_Mateus_M.pdf: 3959646 bytes, checksum: a36674e099fefbc487286cdc33006c0a (MD5) Previous issue date: 2014 / Resumo: A leucemia linfoide aguda (LLA) é o câncer mais comum na infância. O transplante de células primárias de LLA humana em camundongos imunosuprimidos tem sido de suma importância para o entendimento da fisiopatologia da doença e para o teste de novos fármacos. Ao contrário de modelos animais de tumores sólidos, cujo volume é facilmente medido na superfície dos animais, a LLA infiltra órgãos inacessíveis ao exterior, daí a necessidade de definir métodos adequados para o monitoramento da progressão da doença. Resultados aqui apresentados indicam que proteínas secretadas pela LLA podem servir como marcadores quantitativos da carga leucêmica, facilmente aferidos por ELISA de amostras de plasma sanguíneo. Dentre três proteínas testadas (B2M, IGFBP2 e Hsp90), o ELISA de Hsp90 apresentou sensibilidade superior à análise da porcentagem de células leucêmicas no sangue dos animais, por citometria de fluxo de células marcadas com anti-huCD45. Os níveis de Hsp90 humano no plasma sanguíneo mostraram-se positivamente correlacionados com o porcentual de células leucêmicas na medula óssea e fígado e em menor grau com os níveis do baço e sangue periférico (SP) ao longo do tempo, tanto nas LLA de linhagem B quanto nas LLA-T. O ELISA de Hsp90 permite detectar a instauração da leucemia nos animais transplantados, até duas semanas antes da detecção pelo método tradicional de análise de sangue periférico por citometria de fluxo. Ao contrário do observado para IGFBP2, o tratamento dos animais leucêmicos com Dexametasona ou um inibidor da PI3K não interferiu nos níveis de Hsp90, que se mantiveram proporcionais à porcentagem de células leucêmicas huCD45+ no sangue periférico. No conjunto, os resultados demonstram que a análise do plasma dos animais por ELISA de Hsp90 é um método melhor do que os atualmente utilizados, para diagnóstico precoce e acompanhamento de LLA humana quando em níveis de doença residual mínima, ou seja, quando a porcentagem de células de LLA é inferior a 5% do total de células da medula óssea / Abstract: Acute lymphoblastic leukemia (ALL) is the most common type of childhood cancer . The transplantation of human primary ALL cells in immunodeficient mice has been of much importance for understanding the disease's pathophysiology and testing new drugs. Unlike animal models of solid tumors whose volume is easily measured on the animal surface, the ALL infiltrates organs that are inaccessible to external antigens, hence the need to define more suitable methods for monitoring the disease's progression. Results presented here indicate that proteins secreted by the ALL can serve as quantitative markers of leukemic burden and are easily measured by ELISA of blood plasma samples. Among three tested proteins (B2M, IGFBP2 and Hsp90), Hsp90 ELISA analysis showed higher sensitivity than the analysis of leukemic cells on animal blood by flow cytometry of anti- huCD45 labeled cells. The levels of Hsp90 in human blood plasma were shown to be positively correlated with the percentage of leukemic cells in the bone marrow and liver and to a lesser extent with the levels in the spleen and peripheral blood (PB) over time, both in B-lineage ALL as in ALL-T. The Hsp90 ELISA allows the leukemia's engraftment detection in transplanted animals up to two weeks prior to detection by the traditional method of peripheral blood analysis by flow cytometry. Unlike observed for IGFBP2, treatment of leukemic animals with Dexamethasone or PI3K inhibitors did not interfere in Hsp90 levels, which remained proportional to the percentage of huCD45+ leukemic cells in the peripheral blood. Taken together, the results demonstrate that the analysis of animal plasma by Hsp90 ELISA is a better method than those currently used for early diagnosis and monitoring of human ALL on minimal residual disease levels, when the percentage of ALL cells is less than 5 % of the total bone marrow cells / Mestrado / Genetica Animal e Evolução / Mestre em Genética e Biologia Molecular

Les travaux rapportés dans ce mémoire concernent le développement de nouvelles réactions métallo-catalysées pour la création de liaison carbone-hétéroatome et carbone-carbone ainsi que leurs applications à la synthèse de produits biologiquement actifs. La première partie de ce manuscrit est consacrée à l'étude de la réactivité des sucres dans les couplages organométalliques. Des conditions ont été développées pour la création de la liaison C-S entre glycosyl thiols et partenaires arylés. De plus, la création de la liaison carbone azote de glycosyl amines avec des acides boroniques a été étudiée. Les produits synthétisés dans cette première partie ont été évalués pour leur potentiel d'inhibition de la Lectine A chez Pseudomonas aeruginosa, impliquée dans de sévères infections pulmonaires.La seconde partie de ce travail est dédiée à la création d'une série inédite d'analogues du 6BrCaQ, inhibiteurs de la Hsp90 ainsi que leur évaluation biologique. Cette nouvelle série est obtenue grâce à une nouvelle méthodologie de synthèse basée sur l'activation C-H entre un hétérocycle halogéné et son partenaire C-H activable. L'activité antiproliférative et l'inhibition de la Hsp90 ont été évaluées et seront présentées dans ce manuscrit. / The work reported in this dissertation concerns the development of new metal-catalyzed reactions for the creation of carbon-heteroatom and carbon-carbon bonds as well as their applications to the synthesis of biologically active products.The first part of this manuscript is devoted to the study of the reactivity of sugars as nucleophiles in organometallic couplings. Conditions were developed for the creation of the C-S bond between glycosyl thiols and aryl partners. Moreover, the creation of the nitrogen carbon bond of glycosyl amine with boronic acids was studied. The products synthesized in this first part have been evaluated for their potential to inhibit the lectin A, in Pseudomonas aeruginosa related lung infections.The second part of this work is dedicated to the creation of a new series of 6BrCaQ analogues as Hsp90 inhibitors and their biological evaluation. This new series was synthetized through a new CH activation methodology. The antitumoral potential was evaluated and will be presented in this manuscript.

Das Multiple Myelom (MM) ist eine hämatologische Erkrankung, welche sich durch eine Akkumulation von malignen Plasmazellen im Knochenmark auszeichnet und eine gestörte Hämatopoiese und Osteolyse zur Folge hat. Komplexe molekulare Interaktionen zwischen MM-Zellen und der Mikroumgebung/Nische im Knochenmark (bone marrow microenvironment, BMM) führen zu einer Aktivierung von verschiedenen Wachstums-, Überlebens- und anti-apoptotischen Signalwegen, die zur Entstehung bzw. Wirkstoffresistenz von MM-Zellen beitragen. IL-6R/STAT3, Ras/MAPK und PI3K/Akt sind die drei wichtigsten Signalwege, die mit dem Wachstum und der Entwicklung des MM assoziiert sind. Auf der anderen Seite sind Myelomzellen insensitiv gegenüber einer Blockade des IL6R/STAT3-Signalweges bzw. des Ras/MAPK-Signalwegs in der Gegenwart von Knochenmarksstromazellen (bone marrow stroma cells, BMSCs), was die Entbehrlichkeit dieser beiden Signalwege unter Ko-Kultur-Bedingungen nahelegt. Interessanterweise aber induziert die gleichzeitige Unterbrechung der IL6R/STAT3 und Ras/MAPK Signalwege Apoptose in MM-Zellen. Ziel der Arbeit war die Identifizierung und Analyse von Zielgenen, die von beiden Signalwegen und nicht durch einen Signalweg alleine reguliert werden. Genexpressionsanalysen zeigten eine deutliche Herunterregulierung der Proteine Hsp90alpha und Hsp90beta nach einer gleichzeitigen Inhibition der IL6R/STAT3 und Ras/MAPK Signalwege. In Hinblick auf die zentrale Rolle von Hsp90 in der Tumorbiologie fokussiert sich die vorliegende Arbeit auf die Erforschung der Rolle von Hsp90 im Multiplen Myelom. Die siRNA-vermittelte Herunterregulation der Proteinexpression von Hsp90-Proteinen zeigte, daß das Ausschalten von HsP90alpha alleine nur zu einer moderaten Apoptoseinduktion in INA-6- und MM.1s-Zellen führte. Die gleichzeitige Herunterregulation von HsP90beta hingegen führte zu einer Verstärkung dieses Effektes und deutet darauf hin, daß beide Proteine miteinander kooperieren. Die pharmakologische Inhibition der Hsp90-Funktion mittels eines neuen Hsp90-Inhibitors (17-DMAG) führte zu einer Verringerung von phospho-ERK1/2, zur Degradation von STAT3 und zu einem verminderten Überleben von MM-Zellen. Die pro-apoptotischen Effekte der gestörten Hsp90-Funktion konnten weder durch BMSCs und Osteoklasten noch durch ECs (??) abgeschwächt werden, obwohl für ECs beschrieben wurde, daß sie zum Wachstum und Überleben von MM-Zellen beitragen können. Diese Beobachtungen deuten auf einen positiven Rückkopplungskreislauf zwischen HsP90alpha/beta und den wichtigsten Signalwegen hin, welcher das Überleben von MM-Zellen gewährleistet. Desweiteren zeigten immunhistologische Analysen, daß Hsp90-Proteine im Vergleich zu MGUS (??) bzw. normalen Plasmazellen in MM-Plasmazellen hochreguliert sind. Zusammengefasst zeigen die Ergebnisse der vorliegenden Arbeit die essentielle Rolle von Hsp90-Proteinen für die Überlebensfähigkeit von MM-Zellen. Ein neuer Mechanismus der Hsp90-Regulation durch das Zusammenwirken der Signalwege IL6R/STAT3 und Ras/MAPK in MM-Zellen konnte gezeigt werden. Darüber hinaus deuten die Ergebnisse darauf hin, daß ein positiver Rückkopplungskreislauf zwischen Hsp90-Proteinen und den wichtigsten Signalwegen existiert, welcher zum Wachstum und zur Entwicklung von MM-Zellen beiträgt. Die Inhibition der Hsp90-Funktion durch den pharmakologischen Inhibitor 17-DMAG führte zum Absterben von MM-Zellen und der pro-apoptotische Effekt der Hsp90-Depletion konnte nicht durch unterstützende BMM-Zellen aufgehoben werden. Diese Beobachtungen untermauern die multifunktionelle Rolle von Hsp90 in der MM-Biologie und zeigen die Wichtigkeit der Entwicklung neuer therapeutischer Wirkstoffe zur Inhibition der Hsp90-Funktion bei der Behandlung des MM. / Multiple myeloma (MM) is a haematological malignancy characterised by the accumulation of malignant plasma cells in the bone marrow leading to impaired haematopoiesis and osteolytic bone destruction. Intricate molecular interactions between MM cells and the BMM activate a diverse set of growth, survival and anti-apoptotic signaling cascades that mediate tumor progression and drug resistance. IL-6R/STAT3, Ras/MAPK and PI3K/Akt are the three major signal transduction pathways that are associated with MM growth and progression. However, myeloma cells have shown independence from IL-6R/STAT3 blockade or insensitivity towards Ras/MAPK pathway inhibition in the presence of BMSCs, indicating the dispensability of both in co-culture conditions. Interestingly, concomitant disruption of both IL-6R/STAT3 and Ras/MAPK pathways was successful to drive MM cells into significant apoptosis. This study aimed to identify and analyse the downstream target genes that are regulated by both pathways and not by either pathway alone. Gene expression profiling revealed prominent downregulation of Hsp90alpha and Hsp90beta proteins after combined inhibition of the IL-6R/STAT3 and Ras/MAPK pathways. Owing to the important role played by Hsp90 in cancer biology, this study was narrowed down to investigate the role of Hsp90 in MM. Specific siRNA-mediated knockdown of Hsp90 proteins showed that although knockdown of Hsp90beta was sufficient to induce moderate apoptosis in INA-6 and MM.1s cells, the effect was more pronounced when both Hsp90 proteins were targeted, indicating co-operation between them. Pharmacological inhibition of Hsp90 function by using a novel Hsp90 inhibitor (17-DMAG) down-regulated the levels of pERK1/2 and led to degradation of STAT3 and decreased viability of MM cells. The pro-apoptotic effects of compromised Hsp90 function could not be alleviated by either BMSCs, OCs or ECs, which are well-known to support myeloma growth and survival. These observations point to the existence of a positive feedback loop consisting of Hsp90alpha/beta and major signaling pathways supporting MM cell survival. Furthermore, immunohistochemical analysis unveiled the up-regulated status of Hsp90 proteins in MM PCs as compared to MGUS or normal PCs. Taken together, the results of this study explain the critical contribution of Hsp90 proteins to MM cell survival. A novel mechanism of Hsp90 regulation by co-operation between the IL-6R/STAT3 and Ras/MAPK pathways was discovered in myeloma cells. There is also strong evidence of the existence of a positive feedback loop between Hsp90alpha/beta proteins and major signaling pathways supporting MM growth and progression. Inhibition of Hsp90 function by using the Hsp90 inhibitory drug 17-DMAG proved to be lethal for myeloma cells and the pro-apoptotic effects of Hsp90 blockade could not be reversed by the presence of cells from the supportive BMM. These observations highlight a multi-functional role of Hsp90 in MM biology and strongly strengthen the notion that therapeutic strategies targeting Hsp90 may open new perspectives for anti-myeloma drug development.

Οι όγκοι εγκεφάλου αποτελούν μια ομάδα όγκων με ιδιαίτερα χαρακτηριστικά. Η ογκογένεση έχει συσχετισθεί σε αρκετούς όγκους, ανάμεσά τους και ορισμένοι όγκοι εγκεφάλου, με την πρωτείνη θερμικού σοκ 90 (Hsp90). Σε πρόσφατες μελέτες, έχει αποδειχθεί η η συμμετοχή της Hsp90 στην αποδόμηση της ογκοκατασταλτικής πρωτείνης pVHL, η οποία είναι απαραίτητητη για την αποδόμηση του μεταγραφικού παράγοντα που ενεργοποιείται στην υποξία (HIF-1α). Επιπλέον, έχει βρεθεί πως οι ανταγωνιστές της Hsp90 μειώνουν τα επίπεδα έκφρασης του VEGFR-3. Στόχος της παρούσας μελέτης ήταν η εκτίμηση των επιπέδων έκφρασης των μορίων Hsp90, pVHL, HIF-1α και VEGFR-3 στους όγκους εγκεφάλου και οι πιθανές συσχετίσεις μεταξύ τους. Εξετάσθηκαν συνολικά 89 óγκοι εγκεφάλου με την ανοσοϊστοχημική μέθοδο. Στους αστροκυτταρικούς όγκους, η Ηsp90 φαίνεται πως οδηγεί στη σταθεροποίηση του HIF-1α μέσω της σύνδεσής της με τη pVHL. Στα μυελοβλαστώματα από την άλλη, ο HIF-1α ρυθμίζεται από τη Hsp90 με τρόπο ανεξάρτητο από τη pVHL. Βρέθηκε συσχέτιση της έκφρασης του VEGFR-3 με τη Hsp90 αλλά και τον HIF-1α σε ομάδα όγκων του εγκεφάλου, η βιολογική συμπεριφορά των οποίων θα πρέπει να διερευνηθεί. / Brain tumors constitute a special group of tumors. In many tumors, including brain tumors, tumorigenesis has been associated with heat shock protein 90 (Hsp90). ). Recent studies have demonstrated that Hsp90 is essential for the degradation of tumor suppressor protein, pVHL, which is essential for the degradation of Hypoxia Induced Factor 1α (HIF-1α). In addition,it has been proved that Hsp90 antagonists, reduce the expression VEGFR-3. the aim of the current study was to estimate the levels of expression of Hsp90, pVHL, HIF-1α and VEGFR-3 in brain tumors and the possible correlations among them.89 human brain tumors were studied immunohistochemically. In astrocytic tumors, Hsp90 seems to stabilize HIF-1α, through binding to pVHL. On the other hand, in medulloblastomas, HIF-1α seems to be regulated by Hsp90, in a way that seems to be independent from pVHL. We found a correlation between the expression of VEGFR-3 and Hsp90 and HIF-1α in a group of brain tumors, the biological behavior of which must be studied.

Telomerase is a ribonucleoprotein that is reactivated in cancer cells to allow for continuous cellular division and indefinite growth. With telomerase being expressed in more than 85% of all cancer, it is imperative that we understand how to selectively inactivate and degrade this unique DNA polymerase. In doing so, we can specifically target tumor cells to erode their telomeres so that they will undergo apoptosis or senescence. Through this research, we have learned that telomerase can be degraded in the nucleoplasm by Hsp90 chaperone inhibition and in the cytoplasm by the dominant negative mutant, D712A V713I. These findings should guide future drug design to target sites on telomerase that interact with Hsp90 and catalytic divalent metal ions. Previous studies have shown that chaperones function to stabilize the RNP and that their inhibition results in ubiquitin-mediated degradation. However, a detailed understanding of how telomerase is signaled for degradation is not well defined. We showed that Hsp90 inhibition causes telomerase to be degraded by a nuclear ubiquitin/proteasome pathway such that exportation to the cytoplasm is not required. Using confocal fluorescence microscopy and immunoprecipitation /Western analysis, we showed that nucleoplasmic GFP-hTERT is ubiquinated and degraded within 2 hrs of exposure to the Hsp90 inhibitor, Radicicol. Upon combined treatment with the proteasome inhibitor, MG132, degradation is inhibited as shown by Western analysis and fluorescent intensity. Additionally, fluorescent pattern with inhibition of degradation shows telomerase aggregation and co-localization with the nuclear proteasome and not with nucleoli. However, the combined treatment with the exportin inhibitor, Leptomycin B, resulted in complete loss of fluorescence. Taken together, these data suggest that Hsp90 inhibition causes telomerase to immediately undergo nuclear degradation, which may function in the nuclear quality-control of telomerase. The dominant negative expression of telomerase has been shown by many investigators to cause shortening of telomeres. However, the mechanism of how it functions and its fate inside the cell are still unknown. After stably expressing the wild-type and dominant negative mutants GFPhTERT in cells, we show that the D712A V713I mutation causes the ubiquination and degradation of the mutant and wild-type hTERT which eventually leads to the shortening of telomeres. Degradation appears to be cytoplasmic since the additional mutation for the nuclear export signal (nes) and treatment with the exportation inhibitor are able to prevent the reduction in protein levels and fluorescence. Based on this cytoplasmic degradation and the additional co-localization of the GFPDNhTERT to the nucleoli, we propose two new mechanisms of dominant negative hTERT utilizing the theory of interactive dimerization. First, the heterodimer of DNhTERT : wt hTERT may be degraded at a faster rate than the wt hTERT homodimer. Second, the heterodimer may be sequestered in the nucleoli thus diminishing the wild-type hTERT access to the telomere in the nucleoplasm. Overall, we have shown that telomerase can be degraded in the nucleoplasm or cytoplasm depending on the mechanism of inhibition. The significance of this is a better understanding of how Hsp90 inhibition and dominant negative hTERT expression cause the degradation of wild-type hTERT. We have also suggested potential mechanisms of dominant-negative hTERT effect and resistance. With this knowledge, future drug therapies can be designed based on these inhibitors to not only inactivate but also to cause the degradation of an enzyme that is crucially important for the immortalization of cancer cells.

Breast cancer is one of the most prevalent and deadly forms of cancer in women and is not restricted by race or ethnicity. Although a wealth of knowledge has been amassed on the biology of breast cancer, including its risk factors, diagnosis, prognosis, prevention, and treatment, it remains a serious health concern and active area of research. Initial response to standard chemotherapeutic and radiotherapeutic regimens is generally strong for many patients, yet breast tumors often recur, leading to more aggressive and resistant tumors. Because recurrence is such a clinical issue, more effective therapeutic approaches are needed to eliminate partial clinical responses and undesirable side effects. Molecular chaperones like the heat shock protein 90 (Hsp90) family are regarded as ubiquitous, highly conserved proteins that mainly respond upon induction of stress or disruption in cellular homeostasis. Chaperones are critically involved in controlling the conformation, stability, function, and degradation of many oncogenic client proteins by assisting in trafficking, remodeling of improperly folded client proteins, and suppression of protein aggregation. Hsp90-mediated folding events are an ATP-dependent process that involves the association with various co-chaperones and stimulators, including Hsp70, Hsp40, HOP, p23, and Aha1 for client stabilization and modification. Notably, Hsp90 seems to be particularly associated with cell signaling clientele, such as nuclear hormone receptors, protein kinases, and many other oncogenic proteins that directly influence the hallmarks of cancer. In order to define the role of chaperones in breast cancer progression, we assessed chaperone expression levels in normal and tumor lines. Based on our initial finding of increased expression of Hsp90 and p23 in immortal and cancer cell lines, it is possible that this phenomenon may be reflected in normal breast tissue as well as breast carcinoma specimens. Indeed, we observed high Hsp90 expression in invasive carcinomas, such that high nuclear expression correlates with a greater TNM stage, while high cytoplasmic Hsp90 correlates with ER negativity, suggesting that elevated Hsp90 may be an indicator or marker of advanced disease. p23 expression also increases appreciably in established breast cancer cell lines with invasive breast tissue specimens displaying an opposite trend. Although p23 does not appear to have any relationship with TNM stage, significant relationships with ER and PR emerged, with higher nuclear p23 correlating to ER positivity and higher total p23 being positively associated with PR presence. Due to the differential expression of Hsp90 in normal, DCIS, and invasive breast carcinomas, we determined the impact on Hsp90 function, finding that total Hsp90 in tumor cells is associated with an increase in both complexed and uncomplexed Hsp90, which is in contrast to a previously reported study. The intrinsic nature of heat shock proteins makes them especially relevant to a cell’s defense against cancer initiation. The preferential accumulation of Hsp90 in cancer cells also forms the basis for the unique sensitivity of tumor cells to Hsp90 inhibition. The Hsp90 specific inhibitor, radicicol, is more potent in terms of blocking ATPase activity than other Hsp90-related compounds like geldanamycin, which is much more toxic. All Hsp90 inhibitors prevent the association of the co-chaperone p23 with Hsp90, resulting in destabilization of the client protein. For these reasons, it may be possible that Hsp90 inhibition would sensitize breast cancer cells to be more responsive to standard chemotherapeutics. We determined that radicicol negatively alters cellular proliferation, and in combination with Adriamycin, elicits a more robust decline in growth and the expression of Hsp90 client proteins. This finding was associated with an increase in senescent cells without a detectable affect on apoptosis. Radicicol in combination with cisplatin or Taxol contributed to an increase in cell death (apoptosis) and differentially altered the expression of client proteins. Finally, ER negative breast cancer cells do not display altered p53 expression upon radicicol and Adriamycin treatment. Blockade of ER activity in ER positive cells with tamoxifen induced significant reductions in proliferation and decreased p53 expression without a corresponding decrease in p21 levels. In conclusion, these results point to the utility of Hsp90 inhibition as a valid form of targeted therapy for breast cancer, and the value of radicicol as a potential adjuvant treatment option in combination with standard chemotherapeutics.

In the last four years, seven new drugs have been FDA approved for the treatment of late stage melanoma, for the field of melanoma, this marks an incredibly exciting. Three of these new therapies, vemurafenib, dabrafenib and trametinib are small molecule kinase inhibitors that target the MAPK pathway and as such have been approved for the treatment of BRAFV600 mutant melanomas. Yet despite recent advances, mechanisms of intrinsic and acquired BRAF inhibitor resistance continue to undermine uniform and long-lasting therapeutic responses. Several studies have shown that the reactivation of MAPK signaling is a critical event leading to BRAF inhibitor resistance. These studies lead to the evaluation and subsequent FDA approval of frontline BRAF (dabrafenib) plus MEK (trametinib) inhibitors to delay drug resistance. Though this approach has meaningful clinical benefit, there are still a number of patients who do not respond to therapy or who, through unknown mechanisms, succumb to refractory disease. In an effort to identify drivers of MAPK inhibitor resistance, several studies have relied on traditional genomics methods. While gene-based approaches have guided precision medicine, they do not address the dynamics of the global signaling changes that occur following acquired resistance. The dissertation herein will describe our efforts to fill these gaps of knowledge and will expand upon the evolution and development of our understanding of intrinsic and acquired MAPK pathway inhibitor resistance. This work will elaborate on our early understanding of single agent BRAF inhibitor resistance, the use of genomic and proteomic approaches to further elucidate these mechanisms, and evidence based approaches to delay and overcome single agent BRAF inhibitor resistance. This work will describe global phosphoproteomic and bioinformatics methodologies to elucidate the underlying processes of both single (BRAF) and dual agent (BRAF plus MEK) inhibitor resistance as well as strategies to constrain dual agent BRAF plus MEK inhibitor resistance.

Heat shock protein 90 (Hsp90) is an essential and conserved chaperone, required for the conformational maturation and stability of many signaling kinases. We hypothesized that the functional pleiotropism of Hsp90 can be exploited during pharmacological inhibition causing simultaneous restraint of tumor growth as well as suppression of distant spread. Recognizing the lack of therapeutic options in advanced and metastatic squamous cell carcinomas (SCC) of the uterine cervix as well as the oral cavity, this dual concept was tested in corresponding cell lines and xenografts, and correlated with clinical data on client protein expression. Examination of the cell cycle response to Hsp90 inhibition revealed a G2/M-arrest in a panel of four cervical cancer cell lines and a contribution of abnormal mitosis to apoptosis induction in vitro. Although limited to intraperitoneal application, in vivo evidence of biological activity including heat shock response and decreased client kinase phosphorylation was seen with the geldanamycin derivative 17-dimethylaminoethylamino-17-demethoxygeldanamycin (17-DMAG). Importantly, focal adhesion kinase (FAK) signaling and associated functional parameters were inhibited by the drug treatment. Functional significance of FAK as a client was confirmed using a molecular model based on FAK-related non-kinase (FRNK) expression. Dependency on FAK appeared to be a requirement for full response to FRNK as well as 17-DMAG, and was observed in the mesenchymal-like cervical cell line SiHa. FAK expression and E-cadherin loss were features found in both cervical and oral malignancies, but absent from normal mucosa of either anatomic site. Particularly high FAK expression was noted in oral SCC with sarcomatoid features. Thus, we conclude that Hsp90 inhibition has potential in the treatment of advanced and metastatic SCC of cervical and oral origin. The further examination of novel Hsp90-targeting compounds as well as strategies focused on other components of the Hsp90 chaperone complex seems warranted.