Radium-223 in metastatic prostate cancer: effects on metastasis microenvironment

• Autor(a) principal: Tavares, Nuno Tiago Fidalgo
• Data de Publicação: 2019
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/26898
• topic: Prostate cancer; Radium-223; 3D cell culture; Tumor microenvironment

Prostate cancer is the second most frequent neoplasia in males and the fifth cancer-related cause of death worldwide. Androgen deprivation therapy has been the gold standard treatment for advanced prostate cancer. However, in spite of this therapy being associated with the tumour’s remission, it is also associated with prostate cancer recurrence, which leads to a lethal stage of the disease named castration resistant prostate cancer. Despite the high mortality of this stage, nowadays there are some therapy options to manage it, raising survival and providing more life quality to the patients. One of these options is the Radium-223, an alpha particle emitter radiopharmaceutical that has a positive effect on the increasing of overall survival of patients, also lowering the risk of symptomatic skeletal events. The main objectives of this experimental work were to optimize and characterize a three-dimensional cell culture model in two prostate cancer cell lines and then assess the effects of the Radium-223 on the model through molecular and cellular techniques. In the first phase of the work, it was used the magnetic levitation method in order to form three-dimensional spheroids of PC3 and LnCap, using after the MTT assay to check the PC3 model’s influence on the cells metabolism, fluorescence microscopy and histochemical staining techniques to study spheroid structure and viability, immunocytochemistry for protein expression and flow cytometry to learn about the culture’s viability and cell death pathways. The effects of the Radium-223 were then studied by the SRB assay, to evaluate total protein content, by Alamar Blue, to study cell proliferation, and by May-Grünwald-Giemsa staining, to check cellular morphology post-irradiation. The two different cell lines showed different types of three-dimensional structures in culture, and due to its more compact and spherical structure, it was decided to study the PC3 cell line in this experimental work. The PC3 structures displayed a spherical conformation and presented extensive necrotic and apoptotic zones, since the size of the spheroid was in the order of mm2. Besides, the spheroids also exhibited different expression in some key proteins when compared with control cells cultured in monolayer, an important fact when testing cancer therapeutics. After the irradiation of the spheroids with Radium-223, all doses tested presented a decrease compared to the control whether it was in total protein content or cell proliferation. The results also showed that the Radium-223 treatment exhibited a lower efficacy in the spheroids when compared with monolayer cells, which can be due to the fact that the three-dimensional structures are closer to mimicking the in vivo scenario, and so the cytotoxicity of the Radium-223 is decreased. Also, as alpha particles have low penetration ranges and the spheroid has a large size, the radiopharmaceutical might not be properly entering the three-dimensional structure. Thereby, with this work it was possible to conclude that, as expected, the Radium-223 acts differently when tested in monolayer and in three dimensional cultures, as shown by the primary results obtained. Thus, it is very important to evaluate this and, in the future, other drugs or radiopharmaceuticals, using in vitro three dimensional spheroids before passing to in vivo studies, as they can function as a bridge between the two and give more information than standard cell culture, better mimicking the tumor microenvironment.