Monitoring drug-target interactions with methods such as the cellular thermal-shift assay (CETSA) is well established for simple cell systems but remains challenging in vivo. Here we introduce tissue thermal proteome profiling (tissue-TPP), which measures binding of small-molecule drugs to proteins in tissue samples from drug-treated animals by detecting changes in protein thermal stability using quantitative mass spectrometry. We report organ-specific, proteome-wide thermal stability maps and derive target profiles of the non-covalent histone deacetylase inhibitor panobinostat in rat liver, lung, kidney and spleen and of the B-Raf inhibitor vemurafenib in mouse testis. In addition, we devised blood-CETSA and blood-TPP and applied it to measure target and off-target engagement of panobinostat and the BET family inhibitor JQ1 directly in whole blood. Blood-TPP analysis of panobinostat confirmed its binding to known targets and also revealed thermal stabilization of the zinc-finger transcription factor ZNF512. These methods will help to elucidate the mechanisms of drug action in vivo.
Blood/metabolism , Proteome/chemistry , Proteome/metabolism , Small Molecule Libraries/administration & dosage , Animals , Azepines/administration & dosage , Azepines/pharmacology , Hep G2 Cells , Humans , Kidney/chemistry , Kidney/metabolism , Liver/chemistry , Liver/metabolism , Lung/chemistry , Lung/metabolism , Male , Mass Spectrometry , Mice , Organ Specificity , Panobinostat/administration & dosage , Panobinostat/pharmacology , Protein Stability , Rats , Small Molecule Libraries/pharmacology , Spleen/chemistry , Spleen/metabolism , Testis/chemistry , Testis/metabolism , Thermodynamics , Triazoles/administration & dosage , Triazoles/pharmacology , Vemurafenib/administration & dosage , Vemurafenib/pharmacology
