Competitive Kinase Enrichment Proteomics Reveals that Abemaciclib Inhibits Glycogen Synthase Kinase 3 Beta and Activates WNT Signaling

ABSTRACT: The cellular and organismal phenotypic response to a small molecule kinase inhibitor is defined collectively by the inhibitor’s targets and their functions. The selectively of small molecule kinase inhibitors is commonly determined in vitro, using purified kinases and substrates. Recently, competitive chemical proteomics has emerged as a complementary, unbiased, cell-based approach to define the target landscape of kinase inhibitors. Here we evaluated and optimized a competitive multiplexed inhibitor bead mass spectrometry (MIB/MS) platform using cell lysates, live cells and treated mice. Several clinically active kinase inhibitors were profiled, including trametinib, BMS-777607, dasatinib, abemaciclib, and palbociclib. MIB/MS competition analyses of the cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors abemaciclib, and palbociclib revealed overlapping and unique kinase targets. Competitive MIB/MS analysis of abemaciclib revealed 83 target kinases, and dose-response profiling revealed glycogen synthase kinase 3 alpha and beta (GSK3 and GSK3 were the most potently inhibited. Cell based and in vitro kinase assays show that in contrast to palbociclib, abemaciclib directly inhibits (GSK3/β) kinase activity at low nanomolar concentrations. Consequently, abemaciclib activates β-catenin-dependent WNT signaling, as determined by β-catenin transcriptional activation and β-catenin protein stabilization. These data reveal differential kinase target specificities for CDK4/6 inhibitors may help explain differential clinical efficacy and dose-limiting toxicities. More broadly, we highlight the power of competitive chemical proteomics to identify multiple targets of kinase inhibitors in protein lysate, treated cells and in treated mice.

INSTRUMENT(S): Orbitrap Fusion Lumos, LTQ Orbitrap Elite

ORGANISM(S): Homo Sapiens (human) Mus Musculus (mouse)

TISSUE(S): B Cell, Lung, B-lymphocyte, Epithelial Cell, Kidney Cell, Kidney

DISEASE(S): Lung Cancer,Lymphoma

SUBMITTER: Dennis Goldfarb  

LAB HEAD: Ben Major

PROVIDER: PXD006139 | Pride | 2017-12-07

REPOSITORIES: Pride