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Submitted by Ana Lúcia Torres (bfmhuap@gmail.com) on 2017-10-10T15:59:41Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) DISSERTAÇAO JULIO THOME.pdf: 1047008 bytes, checksum: 4e9746314e2b28ff944bb677bb12cbc7 (MD5) / Approved for entry into archive by Ana Lúcia Torres (bfmhuap@gmail.com) on 2017-10-10T15:59:52Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) DISSERTAÇAO JULIO THOME.pdf: 1047008 bytes, checksum: 4e9746314e2b28ff944bb677bb12cbc7 (MD5) / Made available in DSpace on 2017-10-10T15:59:52Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) DISSERTAÇAO JULIO THOME.pdf: 1047008 bytes, checksum: 4e9746314e2b28ff944bb677bb12cbc7 (MD5) Previous issue date: 2010 / Universidade Federal Fluminense. Hospital Universitário Antonio Pedro / Hospital Federal de Ipanema / Hospital Municipal Souza Aguiar / Introdução: Gliomas são tumores cerebrais primários caracterizados pelo crescimento difuso e invasivo. Estudo biomatemático de proliferação e migração dos gliomas propõe que o crescimento de tumores na substância cinzenta profunda cerebral teria um intervalo de tempo maior comparado a lesões situadas na substância branca lobar, onde a invasão e migração seriam mais rápidas. Objetivo: Estabelecer uma correlação da topografia tumoral e edema peritumoral com a resposta terapêutica à administração intranasal do álcool perílico (AP) em pacientes com glioblastoma (GBM) recidivo após tratamento convencional. Métodos: A coorte incluiu o estudo retrospectivo de 119 pacientes com glioma recidivo, sendo 52 em tratamento paliativo de suporte (grupo controle não pareado) e 67 que foram incluídos no Estudo Fase I/II do álcool perílico e receberam administração pela via inalatória de 440 mg de AP diariamente durante o período de Janeiro 2005 a Dezembro 2009. Os parâmetros avaliados incluíram aspectos clínicos e de neuroimagem: topografia tumoral, volume tumoral, presença de desvio da linha média e extensão de edema peritumoral; análise dos dados demográficos, sintomas iniciais e sobrevida global. Análise estatística foi realizada usando testes log rank. A sobrevida global foi determinada pelo método de Kaplan-Meier, incluindo intervalos de confiança de 95%. Resultados: Pacientes do grupo controle apresentaram sobrevida reduzida (p < 0,0001) em relação ao grupo tratado com AP. Dentre os 67 pacientes com GBM, 14 (21%) apresentavam localização talâmica e 53 (79%) localização lobar. Pacientes com tumor localizado na região do tálamo sobreviveram significativamente mais tempo do que aqueles com tumor localizado na região lobar (log rank test, p = 0,0003). Pacientes que apresentaram regressão tumoral acompanhada de redução do edema peritumoral apresentaram resposta clínica positiva, enquanto aqueles com regressão tumoral sem redução do edema peritumoral apresentaram evolução clínica desfavorável, independentemente da topografia tumoral. Presença de desvio da linha média (> 1 cm) foi estatisticamente significante como fator de risco para menor sobrevida (log rank test, p = 0,0062). Conclusões: Este estudo sugere que: (1) pacientes com tumor localizado na região profunda (tálamo) apresentaram sobrevida média maior do que pacientes com tumor localizado na região lobar; (2) edema peritumoral foi um fator determinante na sintomatologia, provavelmente implicado na morbidade podendo estar relacionado com a característica de invasividade do glioma maligno. Esses achados apóiam a teoria de que fatores presentes em diferentes microambientes do tecido cerebral (tálamo, córtex) possam contribuir para o processo de progressão tumoral, para o prognóstico clínico e a resposta terapêutica ao álcool perílico administrado pela vias inalatória / Introduction: Gliomas are primary brain tumors are characterized by diffuse and invasive growth. Study biomathematical proliferation and migration of gliomas suggests that the growth of tumors in deep brain gray matter would have a longer time interval compared with lesions in the lobar white matter, where the invasion and migration would be faster. Objective: To establish a correlation of peritumoral edema and tumor topography with the therapeutic response to intranasal administration of perillyl alcohol (PA) in patients with glioblastoma (GBM) relapsing after conventional treatment. Methods: The cohort included a retrospective study of 119 patients with relapsing glioma, 52 palliative care support (control group) and 67 that were included in the Study Phase I / II and received perillyl alcohol administration by inhalation of 440 mg AP daily during the period January 2005 to December 2009. The parameters evaluated included clinical and neuroimaging: topography tumor, tumor volume, presence of midline shift and extent of peritumoral edema, analysis of demographic data, initial symptoms and overall survival. Statistical analysis was performed using log rank tests. Overall survival was determined by Kaplan-Meier, including 95% confidence intervals. Glioma is a primary brain tumor characterized by diffuse growth and invasiveness. The pattern of differential tumor growth and invasiveness suggest that patients with tumoral lesion located in the lobar white matter region present lower survival rate than patients with lesion located in deep brain gray matter (thalamo). Objective: To establish a correlation between tumor topography and peritumoral edema with the therapeutic response to intranasal administration of perillyl alcohol (POH). Methods: This retrospective study analyzed 119 patients with recurrent glioma being 52 under supportive treatment (control group) and 67 included in the Phase I/II clinical trial that received intranasal administration of 440 mg daily AP from January 2005 to December 2009. The following parameters were analyzed: clinical assessment; demographic data, symptoms and overall survival, neuroimage analysis of topography including tumor volume, midline shift and extent of peritumoral edema. Statistical analysis was performed using log rank tests. The overall survival was determined by the Kaplan-Meier method, including 95% confidence intervals. Results: Patients from control group showed reduced overall survival (p < 0,0001) in comparison with patients included in the Phase I/II that received treatment with perillyl alcohol. Among 67 GBM patients, 14 (21%) had tumoral lesion in the thalamic region and 53 (79%) in the lobar region. Patients with thalamic tumor survived significantly longer than those with tumor located in the lobar region (log rank test, p = 0.0003). Patients with tumor regression with reduction of peritumoral edema had positive clinical response, whereas poor prognosis was observed in those with tumor regression but without reduction of peritumoral edema. Presence of midline shift (> 1 cm) was statistically significant as a risk factor for shorter survival (log rank test, p = 0062). Conclusions: This study indicates that: 1) patients with tumoral lesion in the deep region (thalamic) have longer overall survival than GBM patients with tumors in the lobar region; 2) presence of peritumoral edema contributes strongly to symptoms and is likely to influence morbidity and the invading potential of malignant glioma. These findings support the hypothesis that interaction between glioma cells and different brain microenvironment (thalamo, cortex) can influence the process of glioma progression, clinical prognosis and therapeutic response to intranasal delivery perillyl alcohol

According to the cancer stem cell hypothesis a subpopulation of cells within a tumour has the capacity to sustain its growth. These cells are termed cancer stem cells, and are most simply defined as the cells within a primary tumour that can self-renew, differentiate and regenerate a phenocopy of that cancer when transplanted in vivo. Cancer stem cells have now been prospectively identified from numerous human tumours and are actively sought in many cancer types, both clinical and experimental. The cancer stem cell hypothesis remains controversial, with evidence both supporting and challenging its existence in human tumours and in animal models of disease. Here we prospectively identify and study brain cancer stem cells in clinically representative mouse models of the medulloblastoma and glioma. Cancer stem cells from both mouse brain tumour types are prospectively enriched by fluorescent activated cell sorting freshly dissociated cells for the surface antigen CD15, display a neural precursor phenotype, exhibit the hallmark stem cell characteristics of self-renewal and multilineage differentiation, and regenerate a phenocopy of the original tumour after orthotopic transplantation. Additionally, novel mouse medulloblastoma and glioma cancer stem cell lines were established and studied in vitro as adherent cultures in the same serum-free media conditions that support the growth of normal neural stem cells. When mouse and human glioma stem cell lines were compared, many novel molecular mediators of the tumour phenotype were identified, as were chemical compounds that selectively inhibit their growth. Our results have important implications regarding the cancer stem cell hypothesis, the mechanisms that drive brain tumour stem cell growth and the therapeutic strategies that may prove effective for the treatment of glioma and medulloblastoma.

The main subject of my thesis is the investigation of mechanisms of glioma tumorigenesis associated with the recently identified mutations in isocitrate dehydrogenase. Gliomas account for 80% of primary brain cancers. They represent a diverse group of tumours, and are graded from I-IV based on histopathological features. Whilst grade I tumours may be curable with surgery alone, grade II and III gliomas inevitably progress to glioblastoma multiforme (GBM), which is highly resistant to current therapies and carries a very poor prognosis. Despite an improved understanding of the pathways and mechanisms involved in the development of glioma and its progression to grade IV disease, current and novel treatments have so far failed to significantly improve outcome. Isocitrate dehydrogenase (IDH) enzymes catalyse the oxidative decarboxylation of isocitrate to α-ketoglutarate (&alpha;-KG). Somatic mutations in genes encoding IDH1 and IDH2 were first identified in glioma and subsequently in acute myeloid leukemia and other solid tumours. These heterozygous point mutations occur at the arginine residue of the enzymes active site and cause both loss of normal enzyme function and gain-of-function, causing the reduction of &alpha;-KG to D-2-hydroxyglutarate (D-2HG), which accumulates. D-2HG may act as an oncometabolite through the inhibition of various &alpha;-KG dependent enzymes, stimulating angiogenesis, histone modifications and aberrant DNA methylation. Possibly, IDH1/2 mutations may also cause oncogenic effects through dysregulation of the tricarboxylic acid (TCA) cycle, or by increasing susceptibility to oxidative stress. The exact role of mutant IDH1/2 in tumorigenesis however remains unclear. In the work outlined in this thesis, I have demonstrated that the expression of mutant IDH1/2 in glioma cell lines leads to 2-HG accumultation and a reduction in &alpha;-KG production and results in HIF1&alpha; accumulation and a reduction in 5hmC production. Furthermore, the brain-specific expression of mutant Idh1 in mice also results in 2-HG accumulation and reduced &alpha;-KG production, whilst a reduction in 5hmC levels are also seen. This data appears to support the theory that IDH1/2 mutant activity results in the inhibition of &alpha;-KG dependent enzymes, either through the accumulation of 2-HG or due to a reduction in &alpha;-KG levels. The brain-specific expression of mutant Idh1 in mice also results in increased cellular proliferation and an increase in the expression of the neural stem cell marker, nestin. However gliomas do not develop, perhaps suggesting that additional mutations are required in conjunction with those occuring in IDH1/2 in order to initiate tumourigenesis. Clinically, IDH1/2 mutations may represent a novel therapeutic target in glioma and may also serve as useful diagnostic, prognostic and predictive biomarkers. However, a better understanding of the pathogenesis of mutant IDH is required, to enable effective IDH1/2 directed therapies to be developed in the future.

DNA microarrays represent an ultra-high throughput gene expression assay employed to study the transcriptomic profiles of biological tissues. These devices are increasingly being used to study many aspects of gene regulation, and there is growing interest in the biotechnology and pharmaceutical industries for developing such devices in efforts toward rational product/drug design. The DNA microarray also provides a unique and objective means for diagnosis and prognosis of human diseases based on patterns of gene expression. This is especially important in cancer research and the thrust toward personalized medicine. This dissertation details the design and development of oligonucleotide microarrays and the design and execution of a gene expression study conducted using human glioma specimines. Chapter 2 details the design and development a ~10,000 gene human oligonucleotide microarray. This device consisted of a 21,168 features, each composed of a particular human gene-probe and was applied to the challenge of diagnostic and prognostic estimation for human gliomas (chapter 3). Gliomas are the most frequent and deadly neoplasms of the human brain characterized by a high misdiagnosis rate and low survival. The study in chapter 3 demonstrated that the specified design and development parameters were appropriate for conducting gene expression analysis and that this platform can be used successfully to predict malignancy grade and survival for glioma patients.

by Tung Sin Yi, Cindy. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1994. / Includes bibliographical references (leaves 117-132). / Acknowledgements --- p.I / List of Abbreviations --- p.II / Abstract --- p.IV / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- Astrocytes in the Central Nervous System (CNS) l / Chapter 1.1.1 --- Characteristics of astrocytes / Chapter 1.1.2 --- Functions of astrocytes / Chapter 1.1.2.1 --- General functions of astrocytes / Chapter 1.1.2.2 --- Effects of neuroactive peptides on astrocytes / Chapter 1.1.3 --- Gliomas and the rat C6 glioma cells / Chapter 1.2 --- C-Type natriuretic peptide (CNP) in the CNS --- p.9 / Chapter 1.2.1 --- Structure and distribution of natriuretic peptides in the CNS / Chapter 1.2.2 --- Actions of CNP / Chapter 1.2.3 --- Natriuretic peptide receptors and signal transduction in astrocytes / Chapter 1.3 --- Endothelin-3 (ET-3) in the CNS --- p.18 / Chapter 1.3.1 --- Structure and distribution of endothelins (ETs) in the CNS / Chapter 1.3.2 --- Actions of ET-3 / Chapter 1.3.3 --- Endothelin receptors and signal transductionin astrocytes / Chapter 1.4 --- cGMP second messenger system in astrocytes --- p.28 / Chapter 1.4.1 --- Second messenger systems in astrocytes / Chapter 1.4.2 --- cGMP as second messenger in astrocytes / Chapter 1.4.3 --- Post cGMP cascade effects / Chapter 1.5 --- The aims of this project --- p.33 / Chapter Chapter 2 --- Methods / Chapter 2.1 --- In vitro culture of rat C6 glioma cells --- p.36 / Chapter 2.1.1 --- Preparation of reagents / Chapter 2.1.2 --- Culture of C6 glioma cells / Chapter 2.1.3 --- "Cell plating in 6-well, 24-well and 96-well plastic trays" / Chapter 2.2 --- Determination of cGMP --- p.40 / Chapter 2.2.1 --- Measurement of cGMP / Chapter 2.2.2 --- Data analysis / Chapter 2.3 --- Determination of the effect of CNP on cGMP productionin C6 cells --- p.41 / Chapter 2.4 --- Determination of the effect of ET-3 on the action of CNPin C6cells --- p.44 / Chapter 2.4.1 --- Measurement of intracellular cGMP levels affected by ET-3 / Chapter 2.4.2 --- Measurement of intracellular cGMP levels affected by CNP with ET-3 pretreatment / Chapter 2.5 --- Determination of the effects of PKC activator and inhibitor on CNP-treated C6 cells --- p.46 / Chapter 2.5.1 --- Measurement of intracellular cGMP levels affected by PKC activator or inhibitor / Chapter 2.5.2 --- Measurement of intracellular cGMP levels affected by CNP with PKC activator or inhibitor pretreatment / Chapter 2.5.3 --- Measurement of intracellular cGMP levels affected by CNP with PKC inhibitor antagonized PMA or ET-3 pretreatment / Chapter 2.6 --- Determination of the effect of arachidonic acid on the action of CNP in C6 cells --- p.49 / Chapter 2.7 --- Determination of the effects of ET-3 and CNP on calcium uptake in C6 cells --- p.50 / Chapter 2.8 --- Determination of the effects of CNP and ET-3 on cell volume change in C6 cells --- p.51 / Chapter 2.9 --- Determination of the effects of CNP and ET-3 on glucose and amino acids uptake in C6 cells --- p.53 / Chapter 2.9.1 --- Measurement of glucose uptake in CNP - and/or ET- 3-treated C6 cells / Chapter 2.9.2 --- Measurement of amino acids uptake in CNP - and/or ET-3-treated C6 cells / Chapter 2.10 --- "Determination of thymidine, uridine and leucine incorporation in CNP - and/or ET-3- treated C6 cells" --- p.55 / Chapter Chapter 3 --- Results / Chapter 3.1 --- Effects of CNP and ET-3 on cGMP production in cultured rat C6 glioma cells --- p.56 / Chapter 3.1.1 --- Effect of CNP on cGMP production in cultured C6 glioma cells --- p.57 / Chapter 3.1.1.1 --- The time course of CNP on cGMP production / Chapter 3.1.1.2 --- Dosage-response of CNP on cGMP production / Chapter 3.1.2 --- Effect of ET-3 on cGMP production in C6 glioma cells --- p.61 / Chapter 3.1.2.1 --- Effect of ET-3 on basal cGMP production / Chapter 3.1.2.2 --- Effect of pre-exposure duration to ET-3 on CNP-induced cGMP formation / Chapter 3.1.2.3 --- Dosage-response of ET-3 on CNP-induced cGMP production / Chapter 3.1.3 --- Effect of PMA on cGMP production in C6 glioma cells --- p.65 / Chapter 3.1.3.1 --- Effect of PMA on basal cGMP production / Chapter 3.1.3.2 --- Effect of pre-exposure duration to PMA on CNP-induced cGMP formation / Chapter 3.1.3.3 --- Dosage-response of PMA on CNP-induced cGMP production / Chapter 3.1.4 --- Effects of PKC inhibitors on cGMP production in C6 glioma cells --- p.73 / Chapter 3.1.4.1 --- Effects of PKC inhibitors on basal cGMP production / Chapter 3.1.4.2 --- Effects of PKC inhibitors on CNP-induced cGMP formation / Chapter 3.1.4.3 --- Antagonism of PKC inhibitors on the action of PMA on CNP-induced cGMP formation / Chapter 3.1.4.4 --- Antagonism of PKC inhibitors on the action of ET-3 on CNP-induced cGMP formation / Chapter 3.1.5 --- Effect of arachidonic acid on CNP-induced cGMP production in C6 glioma cells --- p.82 / Chapter 3.2 --- Effects of CNP and ET-3 on cellular metabolism in cultured rat C6 glioma cells --- p.83 / Chapter 3.2.1 --- Effects of CNP and ET-3 on calcium uptake in C6 glioma cells --- p.86 / Chapter 3.2.2 --- Effects of CNP and ET-3 on cell volume changes in C6 glioma cells --- p.89 / Chapter 3.2.3 --- Effects of CNP and ET-3 on glucose and amino acids uptake in C6 glioma cells --- p.91 / Chapter 3.2.4 --- Effects of CNP and ET-3 on C6 cell proliferation --- p.98 / Chapter 3.2.5 --- Effects of CNP and ET-3 on RNA synthesis --- p.101 / Chapter 3.2.6 --- Effects of CNP and ET-3 on protein synthesis --- p.103 / Chapter Chapter 4 --- Discussion and Conclusion --- p.105 / References --- p.117

Submitted by Setor de Tratamento da Informa??o - BC/PUCRS (tede2@pucrs.br) on 2015-05-14T20:39:01Z No. of bitstreams: 1 468555 - Texto Completo.pdf: 8199104 bytes, checksum: 8319f77be38697b0864185d6a700fdf3 (MD5) / Made available in DSpace on 2015-05-14T20:39:01Z (GMT). No. of bitstreams: 1 468555 - Texto Completo.pdf: 8199104 bytes, checksum: 8319f77be38697b0864185d6a700fdf3 (MD5) Previous issue date: 2015-03-10 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / Conselho Nacional de Pesquisa e Desenvolvimento Cient?fico e Tecnol?gico - CNPq / Financiadora de Estudos e Projetos - Finep / Glioblastoma (grade IV) is among the most prevalent primary intracranial tumors and is considered a challenge in oncology and neurosurgery due to the highly aggressive nature, and the elevated mortality rates. The location of the tumor and its invasive nature avoid the standard-of-care therapy, which includes surgical resection followed by radiotherapy and chemotherapy. Nevertheless, the current gold standard treatment has not been effective to prevent tumor evolution, as indicated by the poor survival rates. In this context, we analyzed the GPCRs for kinin and the high-voltagegated calcium channels (VGCC) as feasible new therapeutic approaches in malignant gliomas. Thereby, the signaling triggered by bradykinin or the disruption of calcium signaling might contribute with pivotal mechanisms underlying glioma progression, such as cell proliferation. Therefore, the aim of this study was to further evaluate the relevance of B1 (B1R) and B2 (B2R) kinin receptors as well as the P/Q- and N-type VGCC in glioma development, by using in vitro and in vivo glioma model. Cell culture assay showed that the treatment with the selective B1R des-Arg9-BK (1-100 nM) and B2R BK (1-100 nM) agonists induced a marked enhancement of cell proliferation and viability through ERK1/2 and PI3K/Akt signaling, according to evaluation of U-138MG and U-251MG cell lines. Meanwhile, the incubation of either B1R SSR240612 (1-30 ?M) or B2R HOE-140 (1-100 ?M) antagonists induced a marked cell death with mixed apoptosis/necrosis characteristics. The in vivo mouse model of GL261-induced glioma of C57/BL6 or B1R and B2R knockout mice showed an uncontrolled tumor growing in KOB1R mice. Conversely, there was no significant change of the tumor development in KOB2R mice. Notably, the genetic ablation or the pharmacological combined antagonism of B1R and B2R (SSR240612; 25 nmol/site + HOE-140; 50 pmol/site) diminished the tumor progression as well as the mitotic index of the GL261-induced glioma. To understand the potential anti-tumor effects of the blockade of P/Q- and Ntype VGCC, we used animal-derived inhibitors namely PhTx3-3 (P/Q-type blocker) and Ph?1? (N-type blocker) from P. nigriventer, or MVIIC (P/Q-type blocker) and MVIIA (N-type blocker) from C. magus. The PhTx3-3 (0.3 - 100 pM), Ph?1? (0.3 - 100 pM) and MVIIA (0.3 - 100 pM) displayed a significant inhibitory effect on proliferation and viability of M059J, U-138MG and U-251MG glioma tested cell lines, and evoked cell death mainly with apoptosis characteristics. In the glioblastoma in vivo model, the Ntype VGCC blockade by either Ph?1? (50 pmol/site; i.c.v. and i.t.) or MVIIA (10pmol/site; i.c.v.) caused significant reductions of glioma growth and progression. Of note, the N-type inhibition by Ph?1? and MVIIA led to a marked increase of GFAPactivated astrocytes and Iba-1-positive microglia in the peritumoral area, which might be related to the inhibitory effects of immune system in tumor development. Using molecular and pharmacological approaches, our data provide clear evidence on the beneficial effects of the simultaneous inhibition of both B1R and B2R as well as the P/Q- and N-type blockade on glioma development. Thus, we propose that the combined selective antagonism of B1R and B2R, such as the P/Q-, and especially NP type high-VGCC inhibition could markedly modify the tumor progression, which might represent an attractive alternative for the treatment of malignant gliomas in the future. / O glioblastoma apresenta a maior incid?ncia entre todos os gliomas e se caracteriza como o mais agressivo e fatal (grau IV) dos tumores prim?rios do SNC. Atualmente o glioblastoma ? considerado uns dos grandes desafios da oncologia e da neurocirurgia, devido ao seu car?ter altamente agressivo. A sobrevida m?dia dos pacientes ? bastante baixa e o progn?stico ? desfavor?vel, j? que a grande maioria destes tumores apresenta um padr?o difuso e infiltrativo de crescimento, o que dificulta as abordagens atuais para a terapia tumoral. Neste estudo foram analisados os efeitos dos receptores da fam?lia dos GPCRs de cininas e dos canais de c?lcio voltagem dependentes (CCVD) como base para poss?veis alvos no tratamento dos gliomas malignos, a fim de caracterizar novas abordagens terap?uticas. O efeito da sinaliza??o desencadeada pela BK e da sinaliza??o Ca2+-dependente pode estar envolvida na regula??o do crescimento e progress?o dos gliomas e na migra??o das c?lulas tumorais. Neste sentido, este trabalho visou explorar o papel dos receptores B1 (B1R) e B2 (B2R) de cininas e da sinaliza??o de Ca2+ via CCVD tipo-P/Q e -N em modelo de glioma in vitro e in vivo. Ensaios em cultura celular utilizando as linhagens de glioma humano U-138MG e U-251MG demonstraram que a ativa??o dos B1R e B2R pelo uso dos agonistas desarg9-BK (1-100 nM) e BK (1-100 nM) aumentou a prolifera??o das linhagens celulares testadas, atrav?s da ativa??o das vias ERK1/2 e PI3K/Akt. Enquanto que a exposi??o aos antagonistas seletivos para estes receptores, SSR240612 (1-30 ?M) e HOE-140 (1-100 ?M), provocou intensa morte celular com caracter?sticas de necrose/apoptose. A parte in vivo compreendeu a t?cnica de implante das c?lulas GL261 de glioma (grau IV) em animais C57/BL6 e knockout para os B1R e B2R. A dele??o apenas do B1R provocou um importante crescimento tumoral nos animais knockout para este receptor, enquanto que os animais com dele??o de B2R n?o tiveram o desenvolvimento tumoral alterado. Notavelmente, tanto a dele??o g?nica como o antagonismo farmacol?gico combinado dos receptores B1 e B2 (SSR240612; 25 nmol/s?tio + HOE-140; 50 pmol/s?tio) diminuiu o crescimento tumoral e o ?ndice mit?tico dos gliomas implantados. Para compreender o envolvimento dos CCVD tipo-P/Q e -N na fisiopatologia dos gliomas foram utilizadas fra??es da toxina da aranha Phoneutria nigriventer (PhTx3-3 bloqueadora de canais do tipo-P/Q; Ph?1? bloqueadora de canais do tipo-N) e ?-conotoxinas provenientes do Conus magus (MVIIC bloqueadora de canais do tipo-P/Q; MVIIA bloqueadora de canais do tipo-N). Os experimentos in vitro evidenciaram que o bloqueio dos canais de Ca2+ tipo-P/Q e -N pelas toxinas PhTx3-3 (0.3 - 100 pM), Ph?1? (0.3 - 100 pM) e MVIIA (0.3 - 100 pM) inibiram a prolifera??o e a viabilidade das linhagens celulares M059J, U-138MG e U-251MG de glioma humano, com intensa caracter?stica de morte celular por apoptose. Os resultados utilizando o modelo de glioblastoma in vivo, demonstraram que ambas as toxinas bloqueadoras dos canais do tipo-N, Ph?1? (50 pmol/s?tio) e MVIIA (10 pmol/s?tio), foram efetivas em diminuir o crescimento e a progress?o tumoral nos animais tratados, com intensa ativa??o de astr?citos e micr?glia, destacando o poss?vel envolvimento do sistema imune na inibi??o do crescimento tumoral. Atrav?s do uso de ferramentas moleculares e farmacol?gicas, nossos resultados demonstraram o envolvimento importante tanto dos B1R e B2R de cininas, como dos CCVD tipo-P/Q e -N no desenvolvimento dos gliomas malignos. Desta maneira, podemos propor que o bloqueio farmacol?gico combinado de antagonistas seletivos para os receptores B1 e B2, assim como a inibi??o dos CCVD tipo-P/Q e -N surgem como potenciais alvos terap?uticos no manejo dos tumores cerebrais e podem representar alternativas promissoras no tratamento dos gliomas.

Glioblastoma (GB) é o tumor cerebral humano mais frequente e maligno. O prognóstico dos pacientes com GB permanece alarmante, principalmente devido à baixa eficácia das estratégias terapêuticas atuais além da natureza invasiva desse tipo de câncer. Uma característica de tumores sólidos é apresentar áreas hipóxicas. Microambientes hipóxicos contribuem para a progressão do câncer, resistência ao tratamento e ao prognóstico ruim da doença. Dessa forma, neste trabalho, desenvolvemos um modelo in vitro que se aproxima ao microambiente hipóxico tumoral in vivo. Nossos resultados sugerem que a privação de oxigênio (PO) em combinação com ausência de soro forneceu um ambiente favorável à desdiferenciação das células C6 em células tronco tumorais (CTT). A doxazosina (DOX), um antihipertensivo utilizado na clínica, apresenta efeitos antitumorais em diversos tipos de câncer. Assim, avaliamos o efeito antitumoral da doxazosina em linhagens de glioma de rato (C6) e humano (U138-MG) e a toxicidade do fármaco em culturas primárias de astrócitos e culturas organotípicas de hipocampo. A doxazosina induziu morte celular nas linhagens de glioma e apresentou baixa neurotoxicidade. Além disso, o fármaco inibiu a via da PI3K/Akt e ativou GSK-3β e p53, resultando em indução de apoptose e parada no ciclo celular na fase G0/G1. Considerando a importância da mitocôndria na plasticidade de células tumorais e a resistência ao tratamento apresentada pelos GB, nós analisamos os efeitos da DOX nas interações entre núcleo e mitocôndrias. A DOX induziu biogênese mitocondrial e apoptose nas células C6 e diminuiu secreção de TNF-α. Ao analisar a estrutura química da DOX, encontramos diversas características que indicam que ela possui autofluorescência. Dessa forma, caracterizamos a autofluorescência da DOX em diversos meios. Observamos que há um padrão de distribuição do fármaco nas células C6: ele se encontra ao redor do núcleo e parece estar vesiculado. A superexpressão do receptor do fator de crescimento epidermal (EGFR) está relacionada às formas mais malignas e resistentes de GBs. Portanto, analisamos se a ação antiglioma da DOX está envolvida com EGFR. O tratamento com DOX foi capaz de diminuir os níveis de p-EGFR. O co-tratamento de DOX e AG1478 (inibidor de receptores de tirosina cinase) diminuiu a fosforilação de EGFR e causou necrose. Em vista disso, nossos resultados sugerem que o mecanismo de ação da DOX envolve sinalização de EGFR. Por fim, nós avaliamos os efeitos da DOX livre e nanoencapsulada (DOX-NC) em modelos in vitro e in vivo de glioma. Demonstramos que a DOX-NC induziu morte celular em linhagem de glioma em concentrações 100 vezes menores do que as que utilizamos para a DOX na sua forma livre. Além disso, analisamos o efeito da DOX-NC em culturas organotípicas de hipocampo e, da mesma maneira que o observado com a DOX, a DOX-NC demonstrou baixa toxicidade e diminuiu a área tumoral in vivo, sendo seletiva para células cancerosas. Nesta tese, alteramos o microambiente in vitro de células de glioma, avaliamos os efeitos antitumorais da doxazosina em sua forma livre e nanoencapsulada. Além disso, utilizamos modelos de glioma in vitro e in vivo e em diversos parâmetros celulares, descrevemos a autofluorescência do fármaco e também utilizamos essa característica para avaliar a captação e a distribuição da doxazosina em células de glioma. Nossos resultados contribuíram para aproximar os modelos de estudo com o que ocorre em gliomas in vivo e para evidenciar o potencial terapêutico da doxazosina como um agente antiglioma com baixa toxicidade neural e sistêmica. / Glioblastoma (GB) is the most frequent and malignant human brain tumor. The prognosis of patients with GB remains dismal, mainly due to the low effectiveness of current therapeutic strategies and the invasive nature of this type of cancer. A characteristic of solid tumors is the presence of hypoxic areas. Hypoxic microenvironments contribute to cancer progression, resistance to treatment, and poor prognosis of the disease. Thus, we developed an in vitro model that approximates the hypoxic tumor microenvironment found in vivo. Our results suggest that OD in combination with absence of serum provided an environment favorable to the dedifferentiation of C6 cells in cancer stem cells. Doxazosin (DOX), an antihypertensive used in the clinic, has antitumor effects in several types of cancer. Thus, we evaluated the antitumor effect of DOX on rat (C6) and human (U138-MG) glioma cell lines and drug toxicity in primary astrocyte cultures and organotypic hippocampal cultures. DOX induced cell death in glioma lines and showed low neurotoxicity. In addition, the drug inhibited the PI3K/Akt pathway and activated GSK-3β and p53, resulting in induction of apoptosis and cell cycle arrest in the G0/G1 phase. Considering the importance of mitochondria in the plasticity of tumor cells and the resistance to treatment presented by glioblastomas, we analyzed the effects of DOX the interactions between nucleus and mitochondria. DOX induced mitochondrial biogenesis and apoptosis in C6 cells, and decreased TNF-α secretion. When analyzing the chemical structure doxazosin, we find several characteristics that indicate that it has autofluorescence. Thus, we characterized the autofluorescence of DOX in several media. We observed that there is a pattern of distribution of the drug in the cell: it is around the nucleus and appears to be vesiculated. Overexpression of the Epidermal Growth Factor Receptor (EGFR) is related to the more malignant and resistant forms of GBs. Therefore, we analyzed whether the antiglioma action of DOX is involved with EGFR. DOX treatment was able to decrease p-EGFR levels. Co-treatment of DOX and AG1478 (a receptor tyrosine kinase inhibitor) decreased EGFR phosphorylation and caused necrosis. Thus, our results suggest that the mechanism of action of doxazosin involves EGFR signaling. We evaluated the effects of free and nanoencapsulated doxazosin (DOX-NC) in in vitro and in vivo models of glioma. We demonstrated that nanoencapsulated doxazosin (DOX-NC) induced cell death in a glioma line at concentrations 100 times lower than those used for doxazosin in its free form. In addition, we analyzed the effect of DOX-NC on organotypic hippocampal cultures and, in the same way as observed with DOX, DOX-NC demonstrated low toxicity and decreased tumor area in vivo, being selective for cancer cells. In this dissertation, we altered the in vitro microenvironment of glioma cells, we evaluated the antitumor effects of doxazosin in its free and nanoencapsulated form. In addition, we used glioma models in vitro and in vivo and analyzed several cellular parameters, we described the autofluorescence of the drug and also used this characteristic to evaluate the uptake and distribution of doxazosin in glioma cells. Our results have contributed to approximate the study models with what occurs in gliomas in vivo and to evidence the therapeutic potential of doxazosin as an antiglioma agent with low neural and systemic toxicity.

"July 1999." / Thesis (Ph.D.)--Chinese University of Hong Kong, 1999. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.