Background and rationale: The Alu repeat elements are the most abundant short interspersed repeated elements (SINEs) in human genome. Recently, the accumulation of Alu RNA transcripts, following DICER1 deficit, has been shown to be responsible for a human disease, the dry form of age-related macular degeneration (AMD), Geographic Atrophy (GA). Interestingly, increased levels of Alu RNAs and reduced DICER1 expression have been observed in several cancers, although no correlation has yet been established.The main objective of the present proposal is to determine the potential role of Alu RNAs accumulation in tumor formation and progression.Specific aims: The project will focus on three aims: 1) the analysis of Alu RNA expression in cancer; 2) the study of Alu RNAs-mediated signal in cancer; and 3) the analysis of the inhibition of Alu RNAs accumulation in vivo.Methods: A panel of cancer cell lines and human tumors will be used for qRT-PCR, northern blot, western blot, immunohistochemical analyses and hypoxic studies, in order to determine the expression profile of Alu RNAs and its relation with DICER1 expression in cancer. To study Alu-mediated signaling, the potential involvement of inflammasome and ERK1/2 activation in human tumors and in the cancer cell lines, which express high Alu RNAs levels, will be assessed, carrying out western blot, qRT-PCR, ELISA assays and immunohistochemical analyses. The effect of Alu RNA accumulation on cell fate will be assessed, by performing proliferation, migration and tumorigenesis assays. Stable clones, in which Alu RNAs expression is inhibited, will be generated to study whether inhibition of Alu RNAs accumulation affects tumor growth and metastasis dissemination.Expected outcome: Overall, these findings will provide new insights into the importance of Alu RNA sequences and the non-canonical DICER1 signaling in cancer development and progression, and potentially yield additional, new therapeutic targets.