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Advisor(s)
Abstract(s)
A presença do simportador sódio-iodo (NIS) na membrana plasmática das células de carcinoma diferenciado da tiróide (DTC) é essencial para que a terapêutica com iodo radioactivo (RAI) tenha sucesso. No entanto, em tecido maligno da tiróide, a expressão funcional do NIS encontra-se comprometida e cerca de 30% dos DTC metastáticos tornam-se refractários à terapêutica com RAI. Em muitos destes casos, apesar dos níveis de NIS permanecerem relativamente abundantes, as células mostram-se incapazes de captar iodo suficiente para permitir a terapêutica com RAI. Estas evidências apontam para um NIS disfuncional, nomeadamente em relação à sua abundância e permanência na membrana plasmática. Com este estudo, pretendemos contribuir para a investigação do papel das interacções célula-matriz na expressão funcional do NIS, abordando, em particular, o papel da laminina 5 envolvida nas adesões focais. O estudo tem como principal objectivo avaliar o papel de diferentes componentes da membrana plasmática, nomeadamente de que forma a expressão do NIS influencia a expressão da laminina 5. Considerando, ainda, resultados anteriores que demonstraram que a expressão funcional do NIS depende de interacções célula-célula, também pretendemos analisar de que forma a expressão funcional do NIS influencia a expressão da E-caderina nesse contexto. Utilizando como modelo linhas celulares derivadas de carcinoma da tiróide refratário ao iodo, a linha celular TPC1-CFP que não apresenta expressão endógena de NIS e a linha celular TPC1-NIS-HA que apresenta expressão ectópica de NIS, cultivadas em matrizes de laminina 1 e de laminina 5 separadamente, serão avaliados por quantificação da transcrição reversa da reacção em cadeia da polimerase (RT-qPCR) os níveis de ácido ribonucleico mensageiro (mRNA) da laminina 5 e da E-caderina produzidas endogenamente por estas células, na presença e ausência de NIS membranar. Neste estudo, tentámos abordar a relação entre a expressão de NIS e de laminina 5. Demonstrámos que a expressão da subunidade 𝛃3 da laminina 5 fica reduzida quando o NIS está ausente, facto que pode apoiar o papel desta laminina na expressão funcional do NIS na membrana plasmática. Também pudemos demonstrar que, enquanto as lamininas reduzem a expressão de E-caderina, o NIS induz o seu aumento, resultados que são compatíveis com evidência anterior que demonstra que a E-caderina é uma proteína que participa na retenção do NIS na membrana plasmática. Garantindo que, no futuro, consigamos confirmar a influência positiva da laminina 5 sobre a expressão funcional do NIS, a modulação da laminina 5 pode vir a ser uma intervenção terapêutica em DTCs refractários, nomeadamente para a re-sensibilização à terapêutica com RAI.
The presence of the sodium iodide symporter (NIS) at the basolateral membrane of differentiated thyroid cancer (DTC) cells is essential for the success of radioactive iodide (RAI) therapy. Nevertheless, in malignant thyroid tissue, the functional expression of NIS is compromised and about 30% of metastatic DTC become refractory to RAI therapy. In many of these cases, despite the levels of NIS remaining relatively abundant, cells are incapable of uptaking sufficient iodide for RAI to be successful. This points to a dysfunctional NIS in regards to its abundance and retention at the basolateral membrane. Our purpose with this work is to contribute to the study of cell-matrix interactions and their role in the expression of a functional NIS, focusing specifically on the role of laminin 5 involved in focal adhesions. The general aim of this study is to analyze the role of different components of the plasma membrane, namely how NIS expression influences laminin 5 expression. Considering past results demonstrating that NIS functional expression depends on cell-cell interaction, we also propose to analyze how NIS expression influences E-cadherin expression in that context. Using as our model two cell lines derived from thyroid carcinoma refractory to iodide, the TPC1-CFP cell line with no endogenous NIS expression and the TPC1-NIS-HA cell line with ectopic NIS expression, grown in laminin 1 and laminin 5 matrices separately, we quantified by quantitative reverse-transcription polymerase chain reaction (RT-qPCR) the messenger ribonucleic acid (mRNA) level of laminin 5 and E-cadherin produced endogenously by these cells, in the presence and absence of NIS. In our study, we tried to address the interplay between NIS and laminin 5 expression. We showed that the expression of the 𝛃3 subunit of laminin 5 is reduced when NIS absent, which may support the role of this laminin in NIS functional expression at the plasma membrane. We also showed that laminins reduce E-cadherin expression while NIS increases it, which is consistent with previous results that showed E-cadherin as a participant in NIS retention at the plasma membrane. Provided that, in the future, we can confirm the positive influence of laminin 5 on NIS functional expression, the modulation of laminin 5 can potentially become a therapeutic intervention in refractory DTCs, namely for the re-sensitization of these tumors to RAI therapy.
The presence of the sodium iodide symporter (NIS) at the basolateral membrane of differentiated thyroid cancer (DTC) cells is essential for the success of radioactive iodide (RAI) therapy. Nevertheless, in malignant thyroid tissue, the functional expression of NIS is compromised and about 30% of metastatic DTC become refractory to RAI therapy. In many of these cases, despite the levels of NIS remaining relatively abundant, cells are incapable of uptaking sufficient iodide for RAI to be successful. This points to a dysfunctional NIS in regards to its abundance and retention at the basolateral membrane. Our purpose with this work is to contribute to the study of cell-matrix interactions and their role in the expression of a functional NIS, focusing specifically on the role of laminin 5 involved in focal adhesions. The general aim of this study is to analyze the role of different components of the plasma membrane, namely how NIS expression influences laminin 5 expression. Considering past results demonstrating that NIS functional expression depends on cell-cell interaction, we also propose to analyze how NIS expression influences E-cadherin expression in that context. Using as our model two cell lines derived from thyroid carcinoma refractory to iodide, the TPC1-CFP cell line with no endogenous NIS expression and the TPC1-NIS-HA cell line with ectopic NIS expression, grown in laminin 1 and laminin 5 matrices separately, we quantified by quantitative reverse-transcription polymerase chain reaction (RT-qPCR) the messenger ribonucleic acid (mRNA) level of laminin 5 and E-cadherin produced endogenously by these cells, in the presence and absence of NIS. In our study, we tried to address the interplay between NIS and laminin 5 expression. We showed that the expression of the 𝛃3 subunit of laminin 5 is reduced when NIS absent, which may support the role of this laminin in NIS functional expression at the plasma membrane. We also showed that laminins reduce E-cadherin expression while NIS increases it, which is consistent with previous results that showed E-cadherin as a participant in NIS retention at the plasma membrane. Provided that, in the future, we can confirm the positive influence of laminin 5 on NIS functional expression, the modulation of laminin 5 can potentially become a therapeutic intervention in refractory DTCs, namely for the re-sensitization of these tumors to RAI therapy.
Description
Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2023
Keywords
Iodeto de sódio Simportadores Simportador sódio-iodo (NIS) Iodo radioactivo (RAI) Junções aderentes Lamininas Genética