Francesca Sacco,1,2 Alessandra Silvestri,1 Daniela Posca,1 Stefano Pirro`, 1 Pier Federico Gherardini,1 Luisa Castagnoli,1 Matthias Mann,2, * and Gianni Cesareni1,3,*
Cell Systems 2, 159 – 171, 2016
Metformin is the most frequently prescribed drug for type 2 diabetes. In addition to its hypoglycemic effects, metformin also lowers cancer incidence. This anti-cancer activity is incompletely understood. Here, we profiled the metformin-dependent changes in the proteome and phosphoproteome of breast cancer cells using high-resolution mass spectrometry. In total, we quantified changes of 7,875 proteins and 15,813 phosphosites after metformin changes. To interpret these datasets, we developed a generally applicable strategy that overlays metformin-dependent changes in the proteome and phosphoproteome onto a literature-derived network. This approach suggested that metformin treatment makes cancer cells more sensitive to apoptotic stimuli and less sensitive to pro-growth stimuli. These hypotheses were tested in vivo; as a proof-of-principle, we demonstrated that metformin inhibits the p70S6K-rpS6 axis in a PP2Aphosphatase dependent manner. In conclusion, analysis of deep proteomics reveals both detailed and global mechanisms that contribute to the anti-cancer activity of metformin.
1Department of Biology, University of Rome Tor Vergata, 00133 Rome, Italy 2Department Proteomics and Signal Transduction, Max-Planck Institute of Biochemistry, Martinsried, Germany 3Istituto Ricovero e Cura a Carattere Scientifico, Fondazione Santa Lucia, Rome, Italy