A carregar...
Publicação
Explorar o dano genético induzido pelo estrogénio : nova abordagem terapêutica no cancro de mama
| Nome: | Descrição: | Tamanho: | Formato: | |
|---|---|---|---|---|
| 1.11 MB | Adobe PDF |
Orientador(es)
Resumo(s)
A maioria dos cancros de mama depende do estrogénio para o crescimento. No entanto, durante a ativação da transcrição, o estrogénio leva à formação e acumulação de R-loops (estruturas triplas de ácido nucleico) que, apesar das suas funções fisiológicas, são uma fonte de danos no DNA. Dados preliminares do laboratório de acolhimento (Sérgio Almeida Lab) revelaram a hipótese de que, para fazer face aos danos de DNA provocados pelos R-loops, as células de cancro de mama aumentam a expressão de um conjunto de enzimas que têm como função a supressão de R-loops. O objetivo do projeto conducente a esta tese foi testar esta hipótese e avaliar se a interferência na expressão destas enzimas proporciona novas interações, com possível letalidade sintética das células de cancro de mama hormono-dependentes. Para tal, foram analisados os níveis de transcrição dos genes alvo, a acumulação de R-loops e a indução de danos no DNA aquando da estimulação do estrogénio das células de cancro de mama. Além disso, foi verificado se o bloqueio das enzimas supressoras de R-loops resulta na apoptose destas células. Os resultados obtidos validaram a estimulação do estrogénio nos genes alvo, aumentando os níveis de transcrição do gene da ciclina D1. Foi, também, detetado um aumento dos níveis de R-loops no tratamento com estrogénio, tendo as células tratadas com estrogénio apresentado níveis mais elevados de danos no DNA. Finalmente, os ensaios de apoptose não demonstraram letalidade sintética entre a estimulação do estrogénio e o bloqueio das enzimas supressoras de R-loops. Estes dados, e a sua relevância para os estudos seguintes, são apresentados e discutidos nesta tese.
Most breast cancers rely on estrogen for growth. However, during transcription activation, estrogen leads to the formation and accumulation of R-loops (triple-stranded nucleic acid structures) which, despite their physiological functions, are a source of DNA damage. Preliminary data from the host lab (Sérgio Almeida Lab) disclosed the hypothesis that in order to cope with R-loop-driven DNA damage, breast cancer cells increase the expression of a set of enzymes that are competent to suppress R-loops. The goal of this project was to test this hypothesis and to evaluate whether interfering with the expression of these enzymes affords novel synthetic lethal interactions in hormone-dependent breast cancer cells. For that, the transcription levels of target genes, the accumulation of R-loops, and the induction of DNA damage upon estrogen stimulation of breast cancer cells were analyzed. Moreover, it was evaluated whether the blockage of R-loops suppressor enzymes results in the apoptosis of breast cancer cells. The results validated the stimulation of estrogen in target genes, by increasing the transcript levels of the cyclin D1 gene, and an increase in the levels of R-loops upon treatment with estrogen was detected. In addition, cells treated with estrogen displayed higher levels of DNA damage. Finally, apoptosis assays failed to show synthetic lethality between estrogen stimulation and the depletion of R-loops suppressor enzymes. These data, and their relevance for future works, are presented and discussed in this thesis.
Most breast cancers rely on estrogen for growth. However, during transcription activation, estrogen leads to the formation and accumulation of R-loops (triple-stranded nucleic acid structures) which, despite their physiological functions, are a source of DNA damage. Preliminary data from the host lab (Sérgio Almeida Lab) disclosed the hypothesis that in order to cope with R-loop-driven DNA damage, breast cancer cells increase the expression of a set of enzymes that are competent to suppress R-loops. The goal of this project was to test this hypothesis and to evaluate whether interfering with the expression of these enzymes affords novel synthetic lethal interactions in hormone-dependent breast cancer cells. For that, the transcription levels of target genes, the accumulation of R-loops, and the induction of DNA damage upon estrogen stimulation of breast cancer cells were analyzed. Moreover, it was evaluated whether the blockage of R-loops suppressor enzymes results in the apoptosis of breast cancer cells. The results validated the stimulation of estrogen in target genes, by increasing the transcript levels of the cyclin D1 gene, and an increase in the levels of R-loops upon treatment with estrogen was detected. In addition, cells treated with estrogen displayed higher levels of DNA damage. Finally, apoptosis assays failed to show synthetic lethality between estrogen stimulation and the depletion of R-loops suppressor enzymes. These data, and their relevance for future works, are presented and discussed in this thesis.
Descrição
Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2022
Palavras-chave
Cancro de mama Estrogénio R-loops Dano genético Biologia molecular