Modelo tumoral in vitro para a avaliação terapêutica de fármacos

• Autor(a) principal: Nunes, Ana Raquel Santos
• Data de Publicação: 2018
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.6/9741
• topic: Cancro da Mama; Culturas Celulares 2d; Doxorrubicina; Esferóides; Glutationa; Resistência A Fármacos.; Domínio/Área Científica::Ciências Naturais::Ciências Químicas

The anticancer therapies used nowadays in the clinic display a low efficacy. The ability of cancer cells to develop resistance to drugs used in chemotherapy, contributes to the high mortality associated with this disease. The development of new drug formulations is crucial for improving patient survival rates. In vitro 2D cancer cell cultures have been the main model used, in a first phase, for the development of these new therapies. However, these cultures are unable to mimic the main characteristics of in vivo tumors, such as their drug resistance mechanisms. On the other hand, in vitro 3D cancer models, in particular the cancer cell spheroids, have a drug resistance profile similar to that found in human solid tumors, such as breast cancer. Due to that, these models have been used by researchers as a tool to study anticancer drugs. Nevertheless, the techniques and methods used to analyze the therapeutic efficacy of drugs in in vitro models are developed and standardized only for 2D cells in culture. In this way, the develop of 2D cell culture models that display a drug resistant profile similar to the spheroids can be advantageous since these models can be studied through established equipment, techniques and methodologies. Further investigations revealed that 2D cell cultures obtained by spheroid disintegration and maintained in culture medium supplemented with glutathione (GSH) had the same phenotype as the cells present in 3D spheroids. In the present work, the resistance to doxorubicin (DOX) of 2D cultures of MCF-7 obtained by disaggregation of spheroids and then cultured in culture medium supplemented with GSH was evaluated. The results obtained demonstrated that this model of cell culture presents a DOX resistance profile closer to that presented by spheroids. In fact, the 50 % inhibitory concentration (IC50) of DOX in 3D-derived MCF-7 cell cultures supplemented with GSH was about 8-times higher than that obtained for conventional 2D cell cultures. In this work it was also possible to demonstrate that the increase in resistance of spheroid-derived MCF-7 cells results from increased P-glycoprotein (P-gp) activity and from the reduction of intracellular reactive oxygen species (ROS) levels in these cells. In summary, 2D cell culture obtained from spheroid disaggregation represents an improvement for the future development of anticancer therapies, owing to its ability to present in the 2D model a drug resistance similar to that exhibited by 3D models.