Cell Systems
Volume 2, Issue 3, 23 March 2016, Pages 159-171
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Article
Deep Proteomics of Breast Cancer Cells Reveals that Metformin Rewires Signaling Networks Away from a Pro-growth State

https://doi.org/10.1016/j.cels.2016.02.005Get rights and content
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Highlights

  • Analysis of metformin-mediated changes at transcriptome and phospho-proteome level

  • Strategy to combine literature-derived signaling networks with proteomic data

  • Metformin changes the sensitivity of cancer cells to growth and apoptotic stimuli

  • The mTOR pathway rewiring is dependent on the PP2A phosphatase hyperactivation

Summary

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 PP2A-phosphatase dependent manner. In conclusion, analysis of deep proteomics reveals both detailed and global mechanisms that contribute to the anti-cancer activity of metformin.

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