Quantitative Interrogation of the Human Kinome Perturbed by Two BRAF Inhibitors

Oncogenic
BRAF mutations contribute to the development of a number
of cancers, and small-molecule BRAF inhibitors have been approved
by the Food and Drug Administration (FDA) for anticancer therapy.
In this study, we employed two targeted quantitative proteomics approaches
for monitoring separately the alterations in protein expression and
ATP binding affinities of kinases in cultured human melanoma cells
elicited by two FDA-approved small-molecule BRAF inhibitors, dabrafenib
and vemurafenib. Our results showed that treatment with the two inhibitors
led to markedly different reprograming of the human kinome. Furthermore,
we confirmed that vemurafenib could compromise the ATP binding capacity
of MAP2K5 in vitro and inhibit its kinase activity
in cells. Together, our targeted quantitative proteomic methods revealed
profound changes in expression levels of kinase proteins in cultured
melanoma cells upon treatment with clinically used BRAF inhibitors
and led to the discovery of novel putative target kinases for these
inhibitors.