Profiling the @entity7514 / XXXX pathway in @entity0 using proximity-directed assays identifies correlations between protein complexes and phosphoproteins.

@entity1 @entity0 @entity7514 @entity5 @entity470 @entity406 @entity584 @entity982 @entity10412 @entity1722
BACKGROUND: The identification of @entity1 for targeted antineoplastic therapies requires accurate measurement of therapeutic targets and associated signaling complexes. @entity7514 signaling through heterodimerization is an important growth-promoting mechanism in several @entity5 types and may be a principal resistance mechanism by which @entity470 and @entity1722 expressing @entity5 elude targeted therapies. Current methods that can study these interactions are inadequate for @entity406 -fixed, @entity982 -embedded (FFPE) @entity5 samples. METHODOLOGY AND PRINCIPAL FINDINGS: Herein, we describe a panel of proximity-directed assays capable of measuring protein-interactions and phosphorylation in FFPE samples in the @entity7514 / @entity10412 / @entity584 pathway and examine the capability of these assays to inform on the functional state of the pathway. We used FFPE @entity0 cell line and @entity5 models for this study. In @entity0 cell lines we observe both ligand-dependent and independent activation of the pathway and strong correlations between measured activation of key analytes. When selected cell lines are treated with @entity1722 inhibitors, we not only observe the expected molecular effects based on mechanism of action knowledge, but also novel effects of @entity1722 inhibition on key targets in the HER receptor pathway. Significantly, in a xenograft model of delayed @entity5 fixation, @entity7514 phosphorylation is unstable, while alternate measures of pathway activation, such as formation of the HER3PI3K complex is preserved. Measurements in @entity0 samples showed correlations between @entity7514 phosphorylation and receptor interactions, obviating the need to use phosphorylation as a surrogate for @entity7514 activation. SIGNIFICANCE: This assay system is capable of quantitatively measuring therapeutically relevant responses and enables molecular profiling of receptor networks in both preclinical and @entity5 models.
