Characterization of 53 Multiplexed Targeted Proteomics Assays for Verification Studies in Cancer Cell Lines

The National Cancer Institute's Clinical Proteomics Tumor Analysis Consortium (CPTAC) was established to address the need for improved design, standardization, and validation of proteomics assays to enable better translation of biomarkers from the analytical lab to the clinic. Here, we applied CPTAC guidelines to characterize quantitative mass spectrometry (MS) assays in a new multiple reaction monitoring (MRM) proteomics panel. The panel of 50 proteins was developed in response to a previous study that identified a proteomic profile of altered translational control associated with response to a new cancer drug. MRM-MS assays for 53 peptides of interest were developed, optimized, and characterized on a UPLC system coupled to a triple-quadrupole mass spectrometer (QQQ-MS) using synthetic proteotypic peptides and corresponding stable-isotope labeled internal standard (SIS) peptides. Most of the assays were found to be fit-for-purpose for biomarker verification in that they precisely and reproducibly quantify the peptides at levels corresponding to the endogenous concentration in the desired cancer cell lines. Of these, 28 peptide assays represent to proteins that previously had no associated assays published in the CPTAC database. The targeted proteins in this publicly deposited validated multiplexed panel may be of use for research applications in cancer, cellular stress, neurology, cardiology, and metabolism.