MAPK Pathway Inhibition Reshapes Kinase Chemical Probe Reactivity Reflecting Cellular Activation States. (PubMed, ACS Bio Med Chem Au)
Using electrophilic probes, we show that treatment of BRAFV600E mutant melanoma cells with vemurafenib or trametinib decreases overall cysteine and lysine reactivity in BRAFV600E and MEK1/2, likely reflecting composite changes in amino acid accessibility across multiple reactive residues associated with inhibitor binding...Comparative analysis of ATP-competitive BRAFV600E inhibitors vemurafenib and dabrafenib indicated differences in aspartate and glutamate labeling patterns, consistent with the possibility that ABPP may detect inhibitor-associated variations in residue accessibility, which could reflect differences in inhibitor-bound conformations...Moreover, global proteome analyses of cysteine and lysine reactivity upon BRAFV600E inhibition revealed probe-accessible cysteine labeling changes on KSR2, suggesting a potential MAPK pathway remodeling. Together, these findings highlight ABPP as a valuable chemical biology approach for investigating inhibitor-dependent changes in kinase residue reactivity, offering a framework to investigate how kinase conformational dynamics and signaling pathway adaptation influence the therapeutic response and resistance in cancer.