Investigations have shown that the hypothalamus and pituitary respond to decreases in body temperature by stimulating thyroid release of T_3 and T_4 . This study was designed to bypass the control of the hypothalamus and pituitary gland and investigate the direct effect of temperature on the thyroid gland. Hypothermia was by an in vivo isolated perfusion of the thyroid gland. Radio-immunoassay was used to measure T_3 and T_4 concentrations. Significant increases were observed in animals perfused between 36º and 25ºc. These results indicate that the thyroid gland is directly effected by decreased temperature and that it is capable of exerting control over body temperature independent of the hypothalamus and pituitary gland. Lower perfusion temperatures produced no significant increases.

O iodeto reduz a expressão, cauda poli(A) e taxa de tradução do mRNA da NIS, a partir de 30 min de tratamento. O estudo atual objetivou caracterizar as bases moleculares envolvidas nesses efeitos inibitórios. Células PCCl3 foram tratadas com NaI (10-3M), por diferentes períodos de tempo, e avaliou-se: a meia-vida do mRNA de NIS; o papel das porções 3\'UTR/5\'UTR; o envolvimento de eventos transcricionais; a organização do citoesqueleto de actina; o conteúdo total, meia-vida, degradação, internalização e atividade de NIS; a ativação da via PI3K/Akt. Os resultados evidenciaram que o excesso de iodeto: reduz a meia-vida e interage com a porção 3\'UTR do mRNA de NIS; inibe a atividade do promotor de NIS; desorganiza o citoesqueleto de actina; reduz o conteúdo total, de membrana, a meia-vida e atividade de NIS; aumenta a internalização de NIS por clatrinas, e sua degradação por lissosomos; ativa a via PI3K/Akt. Conclui-se que o iodeto ativa diferentes mecanismos moleculares, transcricionais e pós-transcricionais, para promover o efeito inibitório sobre a expressão de NIS. / Iodide reduces NIS mRNA expression, poly(A) tail length and transcription rate, after 30 min of treatment. The present study aimed to caracterize the molecular basis involved in these inhibitory effects. PCCl3 cells were treated with NaI (10-3M) and assays were performed to evaluate: NIS transcript half-life; the role of NIS mRNA 3\'UTR/5\'UTR; the involvement of transcriptional events; the organization of actin cytoskeleton; the total content, half-life, degradation, internalization and activity of NIS; the activation of PI3K/Akt pathaway. The results indicatred that iodide excess: reduces NIS transcript half-life and interacts with its 3\'UTR portion; inhibits NIS promoter activity; disrupts the actin cytoskeleton; reduces NIS total and membrane content, NIS half-life and NIS activity; induces the internalization of NIS through clathrin and its degradation through lisosomes; activates the PI3K/Akt pathway. In conclusion, iodide activates different molecular mechanisms, transcriptional and post-transcriptional, to promoter the inhibitory effect on NIS expression.

Alterações genéticas nos genes RET, RAS e BRAF resultam na ativação constitutiva da sinalização MAPK e estão presentes em aproximadamente 70% dos carcinomas papilífero de tiroide, a forma mais prevalente de câncer de tiroide. Múltiplas vias de sinalização podem atuar em conjunto com a via MAPK na oncogênese tiroidiana. Nesse estudo, testamos a hipótese que a via MAPK regula a sinalização Notch e que o crosstalk entre as vias de sinalizações são importantes na regulação da diferenciação e proliferação celular no câncer de tiroide. A ativação condicional dos oncogenes RET/PTC3 e BRAFT1799A em linhagem de célula folicular normal de tiroide aumentou a atividade da via de sinalização Notch. Por outro lado, o bloqueio farmacológico da sinalização MAPK reduziu a sinalização Notch na linhagem celular TPC-1 derivada de carcinoma papilífero de tiroide. Glândulas tiroide de animais transgênicos expressando BRAFT1799A e amostras de carcinoma papilífero de tiroide apresentaram elevados níveis de NOTCH1. A superexpressão de NOTCH1 em célula folicular normal de tiroide aumentou a expressão proteica de NIS. A inibição farmacológica e por RNA de interferência da sinalização Notch apresentou um efeito anti-proliferativo em linhagem de CPT. Além disso, a combinação do inibidor farmacológico de Notch e MAPK diminuiu a proliferação de células de carcinoma papilífero de tiroide. Esses dados sugerem um importante papel da sinalização Notch na oncogênese do carcinoma papilífero de tiroide induzida pela sinalização MAPK e que a via Notch pode ser uma potencial terapia adjuvante no câncer de tiroide. / Genetic alterations in RET, RAS and BRAF result in constitutive activation of the MAPK signaling and are present in approximately 70% of papillary thyroid carcinomas, the most prevalent form of thyroid cancer. Multiple signaling pathways can act with MAPK pathway in thyroid oncogenesis. In this study, we tested the hypothesis that MAPK pathway control Notch signaling and that the crosstalk between these pathways plays an important role in thyroid cancer cell differentiation and proliferation. The conditional activation of RET/PTC3 and BRAFT1799A enhanced Notch signaling pathway in normal follicular thyroid cell. By contrast, pharmacological inhibition of MAPK reduced Notch signaling in TPC-1 cell line derived from papillary thyroid carcinoma. Transgenic mice expressing BRAFT1799A restrict in thyroid gland and human papillary thyroid carcinoma samples showed higher Notch1 expression. NOTCH1 overexpression in normal thyroid follicular cell increased NIS protein expression. Pharmacological inhibition and RNA interference of Notch signaling showed an anti-proliferative effect in papillary thyroid carcinoma cells. Furthermore, the combination of MAPK and Notch signaling inhibitors reduced papillary thyroid carcinoma proliferation. These data suggest an important role of Notch signaling in papillary thyroid carcinoma induced by MAPK-related oncogenes and that Notch signaling pathway could be a potential adjuvant therapy in thyroid cancer.

Fan, Dahua. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 117-155). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts also in Chinese.

Although there is strong evidence that thyroid tumors occur more frequently in females than in males, few studies have investigated the role sex hormones play in thyroid carcinogenesis, especially the role of estrogen (E2). This laboratory has previously shown that estrogen receptors (ERs) exist in thyroid papillary carcinoma cells. Continuing along this line of research, we studied the role of E2 and its receptors on the regulation of human thyroid cancer. / In conclusion, we have demonstrated (1) a novel mechanism by which E2 contributes to the proliferation and growth of thyroid cancer cells, (2) that E2 influences the expression of ERalpha and ERbeta differently, causing an imbalance between them, which may change the biological behavior of thyroid cancer cells, giving them the ability to proliferate and resist apoptosis by influencing the level of ERK1/2 activity and subsequently the ratio of anti-apoptotic Bcl-2 to pro-apoptotic Bax, and (3) that the subcellular localization of ERalpha and ERbeta may be a factor that contributes to the differing pathogeneses of papillary and anaplastic thyroid cancers. / To further clarify the mechanism by which E2 promotes cellular proliferation in thyroid cancer cells, we studied the localization of ERalpha and ERbeta in both KAT5 and anaplastic carcinoma cells (FRO) by immunofluorescence staining and by immunoblotting of the proteins in subcellular fractions. Cell proliferation and apoptosis were examined together with the expression of selected apoptotic proteins such as Bax, AIF and cytochrome c. We showed that the subcellular localization of ERalpha and ERbeta differed in papillary and anaplastic thyroid cancer. E2 administration led to an increase in the level of ERalpha in the nuclei of papillary cancer cells while the levels of ERbeta remained unchanged. However, the level of mitochondrial ERbeta surpassed that of ERalpha in anaplastic cancer cells. We also showed that E2 affected caspase-dependent and/or independent apoptosis via ERs in thyroid cancers. / We first studied the molecular pathways by which E2 promotes cellular proliferation in thyroid cancer cells using a human thyroid cancer cell line (KAT5) treated with E2, a selective E2 alpha receptor (ERalpha) agonist (PPT), a selective E2 beta receptor (ERbeta) agonist (DPN), an ERalpha antagonist (MPP), an E2 antagonist (ICI182780) and siRNA, which blocks ERalpha and ERbeta, by MTT assay, DNA fragmentation ELISA, BrdU cell proliferation assay and Western blot. We found that E2 and PPT gradually promoted cell proliferation by increasing the expression of ERalpha and by up-regulating the expression of Bcl-2 and pERK1/2. In contrast, we found that DPN had a negative effect on cell growth by enhancing the expression of ERbeta and Bax and by down-regulating pERK1/2 expression. At the same time, blocking ERalpha significantly reduced the E2-mediated Bcl-2 and pERK1/2 expression. On the other hand, blocking ERbeta markedly enhanced their expression. These results suggest that E2 regulates cellular growth of KAT5 cells by an ER-ERK1/2-MAPK pathway and also that E2 affects mitochondrial homeostasis. / Zeng, Qiang. / "September 2007." / Adviser: George Gong Chen. / Source: Dissertation Abstracts International, Volume: 69-08, Section: B, page: 4616. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (p. 136-154). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.

Alterações genéticas nos genes RET, RAS e BRAF resultam na ativação constitutiva da sinalização MAPK e estão presentes em aproximadamente 70% dos carcinomas papilífero de tiroide, a forma mais prevalente de câncer de tiroide. Múltiplas vias de sinalização podem atuar em conjunto com a via MAPK na oncogênese tiroidiana. Nesse estudo, testamos a hipótese que a via MAPK regula a sinalização Notch e que o crosstalk entre as vias de sinalizações são importantes na regulação da diferenciação e proliferação celular no câncer de tiroide. A ativação condicional dos oncogenes RET/PTC3 e BRAFT1799A em linhagem de célula folicular normal de tiroide aumentou a atividade da via de sinalização Notch. Por outro lado, o bloqueio farmacológico da sinalização MAPK reduziu a sinalização Notch na linhagem celular TPC-1 derivada de carcinoma papilífero de tiroide. Glândulas tiroide de animais transgênicos expressando BRAFT1799A e amostras de carcinoma papilífero de tiroide apresentaram elevados níveis de NOTCH1. A superexpressão de NOTCH1 em célula folicular normal de tiroide aumentou a expressão proteica de NIS. A inibição farmacológica e por RNA de interferência da sinalização Notch apresentou um efeito anti-proliferativo em linhagem de CPT. Além disso, a combinação do inibidor farmacológico de Notch e MAPK diminuiu a proliferação de células de carcinoma papilífero de tiroide. Esses dados sugerem um importante papel da sinalização Notch na oncogênese do carcinoma papilífero de tiroide induzida pela sinalização MAPK e que a via Notch pode ser uma potencial terapia adjuvante no câncer de tiroide. / Genetic alterations in RET, RAS and BRAF result in constitutive activation of the MAPK signaling and are present in approximately 70% of papillary thyroid carcinomas, the most prevalent form of thyroid cancer. Multiple signaling pathways can act with MAPK pathway in thyroid oncogenesis. In this study, we tested the hypothesis that MAPK pathway control Notch signaling and that the crosstalk between these pathways plays an important role in thyroid cancer cell differentiation and proliferation. The conditional activation of RET/PTC3 and BRAFT1799A enhanced Notch signaling pathway in normal follicular thyroid cell. By contrast, pharmacological inhibition of MAPK reduced Notch signaling in TPC-1 cell line derived from papillary thyroid carcinoma. Transgenic mice expressing BRAFT1799A restrict in thyroid gland and human papillary thyroid carcinoma samples showed higher Notch1 expression. NOTCH1 overexpression in normal thyroid follicular cell increased NIS protein expression. Pharmacological inhibition and RNA interference of Notch signaling showed an anti-proliferative effect in papillary thyroid carcinoma cells. Furthermore, the combination of MAPK and Notch signaling inhibitors reduced papillary thyroid carcinoma proliferation. These data suggest an important role of Notch signaling in papillary thyroid carcinoma induced by MAPK-related oncogenes and that Notch signaling pathway could be a potential adjuvant therapy in thyroid cancer.

Submitted by admin tede (tede@pucgoias.edu.br) on 2018-06-20T17:27:19Z No. of bitstreams: 1 THAIS APARECIDA GOMES ALMEIDA.pdf: 1404797 bytes, checksum: 66238507a88b256c3d88b7850c4a0842 (MD5) / Made available in DSpace on 2018-06-20T17:27:19Z (GMT). No. of bitstreams: 1 THAIS APARECIDA GOMES ALMEIDA.pdf: 1404797 bytes, checksum: 66238507a88b256c3d88b7850c4a0842 (MD5) Previous issue date: 2018-03-12 / Thhyroid cancer is the most common malignant neoplasm of the endocrine system and accounts for the majority of deaths reported among these tumors. Papillary thyroid carcinoma (PTC) is the most common histological type, accounting for 85% of all thyroid cancers. The expression of two important genes, CITED-1 and P300, involved in the regulation of several transcriptional factors, has been shown in several tumors; however, to date, no studies have been found in the literature that elucidated the role of P300 and CITED-1 in PTC. The present study aimed to evaluate the expression of the messenger RNA (mRNA) of P300 and CITED-1 in PTC using reverse transcription and real-time quantitative PCR. P300 expression was similar in both tissues, normal (median = 0.052, IIQ = 0.094) and tumor (median = 0.041, IIQ = 0.048) (p = 0.481). In relation to the expression of CITED-1, expression was higher in tumor tissues (median = 0.780, IIQ = 0.881) compared to normal tissues (median = 0.017, IIQ = 0.086) (p <0.0001). Significant association was observed between CITED-1 expression and tumor size, however no association was evidenced between P300 expression and histopathological characteristics of the tumors. P300 is described as a molecule associated with the regulation of CITED-1 and several other genes. CITED-1 is a transcription-specific cofactor, which may explain its overexpression in the tumors evaluated. CITED-1 hyperexpression in PTC suggests that this gene is a candidate for integrating the PTC biomarkers profile, and the fact that CITED-1 is associated with tumor size in later stage tumors may turn it an important candidate as a therapeutic target for these tumors. / O câncer da glândula tireoide é a neoplasia maligna mais comum do sistema endócrino e representa a maioria dos óbitos relatados entre estes tumores. O carcinoma papilífero de tireoide (CPT) é o tipo histológico mais comum, sendo responsável por 85% de todos os cânceres de tireoide. Dois importantes genes, CITED-1 e P300, envolvidos na regulação de diversos fatores transcricionais, foram evidenciados em diversos tumores, no entanto, até o momento, não foram encontrados na literatura estudos que elucidaram o papel de P300 e CITED-1 nos CPT. O presente estudo teve como objetivo avaliar a expressão do RNA-mensageiro (mRNA) de P300 e CITED-1 em CPT utilizando transcrição reversa e PCR quantitativa em tempo real. A expressão de P300 foi semelhante em ambos os tecidos, normal (mediana = 0,052, IIQ = 0,094) e tumoral (mediana = 0,041, IIQ = 0,048) (p = 0,481). Em relação à expressão de CITED-1, a expressão foi maior nos tecidos tumorais (mediana = 0,780, IIQ = 0,881) em relação aos tecidos normais (mediana = 0,017, IIQ = 0,086) (p < 0,0001). Associação significativa foi observada entre a expressão de CITED-1 e o tamanho dos tumores, contudo nenhuma associação foi evidenciada entre expressão de P300 e as características histopatológicas dos tumores. P300 é descrita como uma molécula associada à regulação de CITED-1 e de vários outros genes. CITED-1 é um co-fator específico da transcrição, o que pode explicar sua hiperexpressão nos tumores avaliados. A hiperexpressão de CITED-1 nos CPT sugere que o gene é um candidato a compor o perfil de marcadores dos CPT, e o fato de CITED-1 estar associado ao tamanho tumoral em tumores em estágios mais avançados, pode torná-lo um candidato importante como alvo terapêutico para esses tumores.

This reseach firstly investigated iodine-induced apoptotic effects and the underlying mechanism in thyroid cancer cells. Results indicated that apoptosis induced by iodine, especially at high dose of iodine (100 muM), was mitochondrial-mediated, with the loss of mitochondrial membrane potential, Bak up-regulation, caspase 3 activation and cytochrome C release from mitochondria. Iodine treatment decreased the level of mutant p53 including the R273H mutant that possesses anti-apoptotic features while increased the p21 level. The block of p21 significantly prevented iodine-induced apoptosis. High doses of iodine also stimulated the transient activation of the subfamily members of MAPKs (ERK1/2, p38 and JNK1/2). The results showed the three subfamily members of MAPKs all worked as anti-apoptotic factors. Surprisingly, high doses of iodine promoted instead of suppressed the expression of anti-apoptotic protein Bcl-xL expression. The increase of Bc1-xL was likely to compensate the damage induced by iodine since the inhibition of Bc1-xL accelerated iodine-mediated apoptosis. Collectively, iodine induced mitochondrial-mediated apoptosis in thyroid cancer cells. This apoptotic pathway was involved in the activation of MAPKs pathways, which may subsequently up-regulate p21, Bc1-xL, and down-regulate anti-apoptotic mutant p53 expression. The findings provide solid molecular evidence to explain the epidemiological observation that iodine insufficiency promotes the thyroid tumor development. It may also reveal some novel molecular targets for the treatment of thyroid cancer. / Thyroid cancer is the most common endocrine malignancy and exhibits the full range of malignant behaviors from the relatively indolent occult differentiated thyroid cancer to uniformly aggressive and lethal anaplastic thyroid cancer. Iodine is a well known key element in thyroid normal function maintenance and thyroid cancer development. However, the mechanisms of iodine in thyroid cancer cells development are limited. Recent researches have indicated that iodine could induce cancer cells apoptosis, staying clear from the dysfunction of iodide-specific transportation systems in thyroid cancer cells. Thus, iodine-induced apoptosis may be an effective pathway for iodine to affect thyroid cancer development, but we know little about them. / To further explore iodine on the apoptotic effects of chemotherapeutic agents in thyroid cancer, anaplastic thyroid cancer cell line ARO was used. Anaplastic thyroid cancer is lethal because of its rapid progression and poor response to chemotherapy and radioiodine therapy. The study examined the effect of moderate dose of iodine (50 muM) on the apoptosis of ARO cells treated with doxorubicin (Dox) and histone deacetylase inhibitor sodium butyrate (NaB). The cytotoxic effect of either Dox or NaB alone was limited, but co-administration of NaB and Dox (NaB-Dox) significantly increased mitochondrial-mediated apoptosis. The effects of iodine to apoptosis-induced by the two agents were diversified. Iodine reduced the apoptosis induced by Dox or NaB-Dox but promoted apoptosis induced by NaB. To explain this diversifying finding, the experiment found that iodine exaggerated NaB-mediated Bcl-xL down-regulation. In contrast, it reduced the effect of Dox on the decrease of Bcl-xL expression. Further experiments showed that iodine regulated the level of Bcl-xL in ERK- or/and p38-related pathways. The balance between ERK and p38 may determine the iodine-modulated Bcl-xL expression. The high ERK/p38 activity ratio up-regulated Bc1-xL and enabled the tumor cells to resist chemotherapy, whereas the low ERK/p38 down-regulated Bc1-xL and sensitized the tumor cells to chemotherapy. Taken together, iodine plays a critical role in apoptosis of thyroid cancer cells induced by chemotherapeutic agents. The balance between ERK and p38 may determine cell survival and death through modulating Bcl-xL expression in thyroid cancer cells. The findings provide some new insights into the roles of iodine in chemotherapeutic agents-induced apoptosis in thyroid cancer cells. / To summarize, iodine-induced apoptotic effects on thyroid cancer cells is a key pathway for iodine to influence thyroid cancer development and chemotherapy. Meanwhile MAPKs-related mutant p53, p21 and Bcl-xL expression are critical in deciding thyroid cancer cells survival and death. Moreover, iodine can influence chemotherapeutic agents-induced apoptosis through ERK/p38-mediated Bcl-xL expression. / Liu, Xiaohong. / "December 2009." / Adviser: Charles Andrew van Hasselt. / Source: Dissertation Abstracts International, Volume: 72-01, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 111-146). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Source: Masters Abstracts International, Volume: 47-06, page: 3373. Adviser: Wenyaw Chan. Includes bibliographical references.

The hypothalamic-pituitary-thyroid axis operates to maintain the circulating concentration of thyroid hormones. Thyrotropin releasing hormone (TRH) is the major hypothalamic messenger controlling the pituitary-thyroid unit. However, the pituitary-thyroid unit responses to various modalities of TRH exposure are not well characterized. Also, interactions between the thyroid axis and other mammalian organ systems, specifically other hormone axes, to maintain the organism's homeostatic state are not well characterized. This work was designed to clarify the response of the pituitary-thyroid unit to TRH and to assess the effects of physiological levels of the rat's primary adrenal cortical hormone, corticosterone, on the thyroid axis. Adult rats were given equal amounts of TRH by intravenous (I.V.) bolus injection or constant intraperitoneal (I.P.) infusion. Both methods resulted in significant increases in plasma thyroid stimulating hormone (TSH), although the time course and peak plasma value varied with the TRH dosage and administration method. Despite the differences in plasma TSH elicited, the thyroid gland responses were similar. Thus, the pituitary is sensitive to the rate and dose of TRH administration. Also, the thyroid is sensitive to plasma levels of TSH but reaches maximum stimulation at submaximal circulating TSH levels. Adrenalectomized female rats, with I.P. and I.V. catheters, were infused with corticosterone (B) to achieve plasma levels within the rat's physiological range. Plasma samples were drawn before and after submaximal TRH (250 ng/100 g Body Weight) administration for assay of TSH and B concentrations. B in the lower half of its physiological range significantly inhibited the increase in plasma TSH observed 10 and 30 minutes after TRH administration. Also, direct stereotaxic infusion of B (50 ng) followed by TRH (1 ng) into the anterior pituitary inhibited the observed increase in plasma TSH. These studies indicate that homeostatic thyroid axis hormone concentrations are maintained by a feedback loop mechanism which is modulated by adrenal hormones. Specifically, physiological levels of corticosterone decrease pituitary sensitivity to TRH in the rat. In addition, the pituitary and thyroid gland exhibit different response patterns to hormonal stimulation.