The insulin-like growth factor (IGF) system plays an important role in tumorigenesis. IGF1R overexpression has been demonstrated in a variety of tumors, suggesting that its expression is a fundamental prerequisite for cellular transformation. Recently, we demonstrated IGF1R overexpression in 66.6% and 20% of pediatric and adult tumors, respectively. Silencing of IGF1R by RNA interference (RNAi) has been described in lung, colon and liver tumors. This mechanism was able to decrease the cell proliferation rates and induce apoptosis, in addition to make tumor cells more sensitive to chemotherapeutic agents. In the present work we will induce IGF1R gene silencing by RNAi in cell lines of human adrenocortical tumors. Two distinct cell lines (NCI H295 and T7) will be cultivated and subjected to treatment with specific IGF1R RNAi. IGF-1R gene and protein expression will be determined by the techniques of real-time PCR and Western blot. The effects of in vitro silencing will be evaluated by cell proliferation assays and analysis of activity of caspases. Additionally, we will evaluate the expression of microRNA 145 and microRNA 100 in 50 adrenocortical tumors diagnosed in adults and children by real-time PCR technique. Inhibition of IGF1R gene expression represents a potential target and has a great interest in obtaining new and effective therapeutic options for human adrenocortical tumors.
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