AbstractsBiology & Animal Science

MiRNAs expression profiling and modulation in Glioblastoma Stem Cells; Avaliação do perfil de expressão de miRNAs e sua modulação em Células Estaminais de Glioblastoma

by Rúben Miguel Branco

Institution: Universidade de Coimbra
Year: 2014
Keywords: Glioblastoma multiforme; Células estaminais cancerígenas; MicroRNAs; Terapia génica; Resistência terapêutica
Record ID: 1323722
Full text PDF: http://hdl.handle.net/10316/28175


Among all brain cancers, glioblastoma multiforme (GBM) is the most common, malignant and lethal type of tumor. Standard treatment consists on the removal of the tumor mass with surgery, followed by chemotherapy and radiotherapy. Despite the recent advances in therapy, the life expectancy of GBM patients after diagnosis is very low. For this reason, new therapeutic approaches for GBM are urgently needed. The discovery of cancer stem cells opens the possibility for new types of therapy. Beyond their capacity for self-renewal and tumorigenesis, these cells are known for their high resistance to radiotherapy and chemotherapy, when compared to other cancer cells. Since these cells can remain in the tissue and form a new tumor even after treatment, it seems essential to develop therapeutic strategies that target cancer stem cells, with the ultimate goal of eradicating the tumor. In this regard, miRNAs have received special attention from the scientific community in recent years. A large number of studies has suggested that miRNAs play important roles in the development of malignant gliomas. Taking this into account, therapies for GBM based on miRNA modulation are a promising field of research. In this study, we proposed to isolate and characterize the glioblastoma stem cell (GSCs) population present in the U87 human glioblastoma cell line. Our results showed that cells isolated from this cell line, using magnetic CD133-microbeads, express nestin and CD133, two well established cancer stem cells markers, and grow in the form of neurospheres in low-adhesion conditions. Our second goal was to compare the miRNA profile of GCSs and other GBM cells and assess the potential of miRNA modulation in the GSCs, with therapeutic purposes. We found that CD133+ and CD133- cells showed different miRNA profiles, especially in what concerns miR-128 expression, since this miRNA was highly downregulated in CD133+ cells. We also evaluated the effect of miR-128 overexpression, alone or in combination with the drug sunitinib, in GBM tumor cell viability. These experiments allowed us to demonstrate that miR-128 overexpression sensitized U87 cells to sunitinib-induced cell death. Since we were unable to deliver miR-128 mimics to the GSC population using commercially available nucleic acid delivery systems, we developed preliminary studies aiming at evaluating the possibility of using stable nucleic acid delivery particles, coupledto the chlorotoxin peptide, to perform miRNA modulation in these cells. We showed that these nanoparticles were able to deliver miRNA mimics to GSCs with high efficiency. Overall, we found evidences that point to an important role of miRNAs in GSC stem properties and that may help to clarify the contribution of these cells to tumor progression, paving the way to the development of new miRNA-based therapeutic strategies for GBM treatment.; Entre todos os tipos de cancro de cérebro, o glioblastoma multiforme (GBM) é o tipo de tumor mais comum, maligno e letal. O tratamento padrão para este tipo de cancro consiste na remoção…