Glioblastoma multiforme (GBM) is a lethal tumor and radiation therapy remains one of the main treatments. New strategies are needed to overcome the resistance to treatment; one of which is based on the inhibition of transcription factors (TFs) activity. There is evidence that E2F family members may be promising targets for anti-cancer therapy due to their functions related to proliferation, apoptosis, invasion, cell cycle and DNA repair. Some of them (E2F1 and E2F4) has been reported to be overexpressed in GBM compared to samples of normal brain tissues. The functional overlapping of E2F proteins can be overcome by treatment with the small molecule HLM006474, which is an inhibitor of E2F protein family members (E2F1-8); the inhibitor is an 8-hydroxyquinoline compound, whose antiproliferative and pro-apoptosis properties were demonstrated in tumor cells. The hypothesis of this project is that decreased levels of E2F in GBM cells would increase the sensitivity of tumor cells to the effects of gamma-irradiation. We will also assess the role of DNA repair, NHEJ (non-homologous end-joining method) pathway, in the cellular responses by using two GBM cell lines, M059K and M059J, which are deficient and wild-type for the DNA-PK enzyme, respectively. To test this hypothesis, several assays will be performed at cellular level (analysis of proliferation and viability, clonogenic survival, apoptosis and cell cycle kinetics); in addition, we will evaluate the kinetics of repair of double strand breaks in the DNA (detection of gamma-H2AX) and transcriptional expression profiles at genome-wide scale (microarrays). Thus, we expect that the results to be obtained in this project can provide key information for designing new therapeutic strategies based on the molecular inhibition of E2F, seeking for GBM radio-sensitization.
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