Diss. (sammanfattning) Stockholm : Karol. inst., 2007. / Härtill 4 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 3 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2006. / Härtill 4 uppsatser.

Thesis (Ph. D.)--University of Washington, 2007. / Vita. Includes bibliographical references (p. 133-145).

Abstract Colorectal cancer is the second most common malignancy in the Western World. The overall 5-year survival is still only 50–60%. Thus, better prognostic markers are needed to improve survival of the disease. Most colorectal cancers develop from pre-existing adenomas including conventional, flat and serrated adenomas. The most important prognostic factors include tumour stage, histologic subtype and poor differentiation. The prognosis of colorectal cancer depends mainly on tumour stage. The growth of colorectal cancer is determined by cell proliferation, differentation and apoptosis. The progression of colorectal cancer is associated with the growth pattern of colorectal cancer and its invasive margin. Cancer cell budding means the presence of cells scattered in the stroma at the invasive margin, and is associated with β-catenin, an adhesion protein involved in the nuclear Wnt/β-catenin pathway. Hormones may be directly involved in the growth of a cancer, for example sex hormones play an important role in the development of most gynaecological cancers. The knowledge about the dependency of cancers on other hormones, such as thyroid hormones, is limited. This thesis focuses on factors affecting growth and prognosis in colorectal cancer. Antibodies for Ki-67, caspase cleavage site for keratin 18, β-catenin and TRβ1 were used to determine their possible associations with colorectal cancer growth patterns and the characteristics of the invasive margin. Apoptosis and proliferation were decreased at the invasive margin, particularly in serrated adenocarcinomas. The invasive margin showed a presence of budding cell clusters in 24.0% of the cases and this predicted a very poor 5-year-survival (15.4%, P < 0.00001), but nuclear β-catenin accumulation did not predict budding. Thyroid hormone receptor TRβ1 was associated with polypoid growth, presence of KRAS mutations and also with a higher WHO histological grade and advanced Dukes' stage, and in in vitro analysis, thyroid hormone T3 had a modulatory effect on colorectal cancer cell protein synthesis and apoptosis. In conclusion, the growth type of colorectal cancer, i.e. conventional polypoid, flat or serrated, has an association with the characteristics of the invasive margin. Budding margin is associated with poor prognosis in colorectal cancer, and could be utilised in diagnostic pathology. Association of TRβ1 expression with polypoid growth pattern and the presence of KRAS mutations suggest that abnormalities in thyroid hormone signalling involving TRβ1 play a role in the development of some types of colorectal adenocarcinomas.

Dissertation (Ph.D.)--University of South Florida, 2009. / Title from PDF of title page. Document formatted into pages; contains 86 pages. Includes vita. Includes bibliographical references.

Dissertation (Ph.D.)--University of South Florida, 2009. / Includes vita. Includes bibliographical references. Also available online.

Os receptores dos hormônios da tireóide (TRs) são fatores de transcrição envolvidos na diferenciação celular, metabolismo e funções fisiológicas da maioria dos tecidos. Muitos estudos mostram que diversos efeitos farmacológicos mediados pelos TRs podem ser benéficos na farmacoterapia, especialmente aqueles mediados pelo TR que podem ser úteis em condições médicas importantes como obesidade, hipercolesterolemia e diabetes. Além disso, a descoberta que o TR é a isoforma predominante no coração, mediando a maioria dos efeitos cardiovasculares prejudiciais, estimulou a pesquisa por ligantes seletivos para o TR que poderiam ser utilizados em quadros clínicos importantes com perfil de segurança aceitável. Foi realizado um estudo das relações quantitativas entre a estrutura e atividade (QSAR) de um conjunto de compostos com atividade biológica descrita para TR e TR, que gerou modelos de Holograma QSAR com elevada consistência interna e externa, apresentando bom poder de correlação e predição das propriedades biológicas. Também foi realizado um minucioso estudo de triagem virtual, que propiciou a seleção de 7 compostos que foram adquiridos para terem suas atividades biológicas avaliadas. Ensaios de transfecção e gene repórter foram estabelecidos e utilizados na avaliação da atividade biológica dos compostos selecionados pelo ensaio virtual. Finalmente, um ensaio utilizando ressonância plasmônica de superfície (SPR) foi desenvolvido e utilizado para avaliar a atividade agonista desses compostos, e que pode ser útil para avaliar a atividade de novos ligantes. A técnica de SPR também foi empregada em um cuidadoso estudo da interação do TR com seus correguladores, que incluiu estudos cinéticos e termodinâmicos, propiciando a determinação das taxas cinéticas e parâmetros termodinâmicos para a interação do complexo TR-T3 com peptídeos derivados de dois de seus correguladores. Os resultados obtidos são relevantes e devem ser considerados no planejamento de futuros experimentos utilizando o LBD de TR e agonistas. / The thyroid hormone receptors (TRs) are transcriptional factors involved in cell differentiation, development, metabolism and physiological function of most tissues. Many lines of evidence show that several pharmacological actions of TRs might be beneficial in medical therapy, specially those mediated by TR that target important medical conditions like obesity, hypercholesterolemia and diabetes. Additionally, the findings that TR is the predominant isoform in the heart and mediates most of the TRs deleterious cardiovascular effects, stimulated the research for selective TR ligands which could address important medical needs with an acceptable safety profile. In this PhD thesis, studies of the quantitative structure-activity relationships (QSAR) of a dataset of compounds with reported biologic activity for both TR and TR were performed, and statistically significant Hologram QSAR models with good predictive ability for untested compounds were created. In parallel, a careful virtual screening procedure was executed, leading to the selection of 7 compounds which were purchased for the evaluation of their biological activities. Cell transfection and reporter gene assays were developed, validated and used to evaluate the biological activities of these compounds. Finally, a surface plasmon resonance (SPR) assay was developed and used to assess the agonistic activity of these compounds. The SPR technique was also employed in a careful study of the interaction between the ligand binding domain of TR and peptides derived from its coregulators, which included the determination of the kinetic and thermodynamic parameters for this interaction. The results suggest that flexibility plays an important role in the interaction between the receptor and its coregulators, and point out important aspects of experimental design that should be addressed when using TR LBD and its agonists. Furthermore, the methodology described here may be useful for the identification of new TR ligands.

Sabe-se que o hipotireoidismo (Hipo) resulta em supressão do eixo hormônio de crescimento (GH)/ insulin-like growth factor I (IGF-I) e em atraso no desenvolvimento esquelético. Em um estudo anterior, vimos que o tratamento de ratas jovens Hipo com GC-1, um análogo da triiodotironina (T3) seletivo pela isoforma <font face=\"symbol\">b de receptor de hormônio tireoideano (TR<font face=\"symbol\">b), não teve efeito sobre o IGF-I sérico ou sobre a expressão protéica de IGF-I nas lâminas epifisiais, mas parcialmente reverteu alterações esqueléticas decorrentes do Hipo, o que sugere que: (i) o desenvolvimento esquelético requer ações do T3 mediadas pelo TR<font face=\"symbol\">a1 e TR<font face=\"symbol\">b1 (isoformas de TR expressas no osso); ou (ii) requer interações entre o eixo GH/IGF-I e o hormônio tireoideano. Neste estudo, investigamos essas hipóteses tratando ratas recém desmamadas Hipo com T3 ou GC-1 em associação ou não com o GH por 4 semanas. Os nossos achados mostram que o T3 e GH interagem para promover o desenvolvimento ósseo, mas que uma série de efeitos do T3 nesse processo independe do eixo GH/IGF-I e são mediadas pelo TR<font face=\"symbol\">a e/ou TR<font face=\"symbol\">b. / Thyroid hormone (TH) has important effects on bone development and metabolism. It is known that triiodotyronine (T3) has indirect actions in the skeleton through its influence on the production and secretion of growth hormone (GH)/ insulin-like growth factor (IGF-I) and/or other factors. On the other hand, direct actions of T3 on bone are recognized but not yet clear. Most of T3 action is mediaded by its nuclear receptors (TRs). TR<font face=\"symbol\">a1, TR<font face=\"symbol\">b1 e TR<font face=\"symbol\">b2 bind T3, while TR<font face=\"symbol\">a2 does not bind T3 and acts as an antagonist of genic transcription of TR<font face=\"symbol\">a1 and TR<font face=\"symbol\">b1. All these receptors, except TR<font face=\"symbol\">b2, are expressed in chondrocytes of growth plate, osteoblasts and osteoclastos. However, the functional roles of each TR isoformas in the bone development are incompletely understood. A few years, it is development GC-1, a synthetic analog of T3 which is selectivwe for TR<font face=\"symbol\">b1 over TR<font face=\"symbol\">a1. In recent study, we showed that treatment of hypothyroid young rats with T3 revert the IGF-I deficiency and skeleton defects caused by hypothyroidism. Since GC-1 treatment does not effects on serum levels of IGF-I or protein expression of IGF-I in the growth plate, but revert some bone alterations induced by T3 deficiency. Considering the selectivity of GC-1 for TR<font face=\"symbol\">b, these findings suggest that T3 has effects on bone development that are mediated by TR<font face=\"symbol\">b and independent of GH/IGF-I axis. On the other hand, the inability of GC-1 in completely revert the alterations of bone development suggests that the normal skeleton development require (i) T3 actions mediated by TR<font face=\"symbol\">a1 and TR<font face=\"symbol\">b1, or (ii) synergic or additive actions between GH/IGF-I axis and thyroid hormone. To investigate these hypotheses, 21 day-old hypothyroid female rats were treated with T3 or GC-1 in association or not with GH for 4 weeks. Our findings show that T3 interacts with GH to promote body growth, differentiation of growth plate hypertrofic chondrocytes, intramembranous ossification of cranial bone, and increased of bone resistance and other biomechanics parameters that contribute to the best bone quality. On the other hand, ours results suggest strongly that TH acts in bone mass acquisition, in organization of growth plate chondrocytes and endocondral ossification mainly independent of GH/IGF-I axis and via TR<font face=\"symbol\">a and/or TR<font face=\"symbol\">b.

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