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| Author(s): |
Marília Meira Dias
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Faculdade de Ciências Médicas |
| Defense date: | 2012-02-24 |
| Examining board members: |
José Barreto Campello Carvalheira;
Francisco Rafael Martins Laurindo;
José Andrés Yunes;
Roger Chammas;
Sara Teresinha Olalla Saad
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| Advisor: | Marcelo Ganzarolli de Oliveira; José Barreto Campello Carvalheira |
| Abstract | |
S-Nitrosation is a dynamic and reversible post-translational modification of proteins that controls important cellular functions through the modification of cysteine thiol side chains by nitric oxide (NO). mTOR signaling pathway deregulation is involved in various cancer types and contributes to cancer cell proliferation as well as growth factor independence. The aim of this work was to analyze the mechanisms by which S-nitrosogluthatione (GSNO) affects mTOR function. S-nitrosation of mTOR was assessed by the Biotin Switch Method. GSNO was shown to S-nitrosate mTOR with a consequent time- and dose-dependent decrease in the phosphorylation of mTOR and S6K proteins, which were reversed by the addition of the denitrosating agent DTT. Pre-treatments of cells with the inhibitor of soluble guanylyl cyclase, ODQ, or with the NO scavenger, PTIO, had no effect on the GSNO-mediated decrease in phosphorylation of mTOR and its substrates p70S6K and 4EBP-1. Results also demonstrated that cancer cell line viability decreased after exposure to the NO donors GSNO and S-nitroso-N-acetyl-cysteine (SNAC), altering proliferation and increasing cell death. PC-3, MCF-7 and MDA-MB-468 cell lines, which have mutations in the PI3K-mTOR pathway, showed a greater response to GSNO. Therefore, S-nitrosation is a novel post-translational modification capable of modulating mTOR activity, with possible therapeutic implications (AU) | |