Celecoxib was observed in our in vitro

EGFR somatic doublet mutations are potentially more frequent than previously understood, with majority of them representing driver driver mutations rather than driver passenger mutations. Future kinome targeted therapies should take into Celecoxib account of oncogenic effects of doublet mutations in the targets and detailed analysis of the identified doublet mutations would be warranted. Through sequence bioinformatics and structural analysis, we identified the highly conserved E884 R958 ion pair in EGFR kinase domain that is conserved, both by sequence homology and by structural salt bridge formation, across the entire human kinome. Many of the protein kinases in the human kinome are druggable therapeutic targets for various human cancers.
This striking finding provides a structural basis for the potential CH5132799 mechanism of alteration of substrate specificity. This hypothesis is substantiated by our study using mutational disruption of the E884 R958 ion pair via a R958D substitution resulting in an opposite electrostatic charge between the wild type and the mutant residue at codon 958. Similar differential sensitivity towards gefitinib and erlotinib was observed in our in vitro EGFR inhibition study here. It is interesting to note that this salt bridge is located directly between two regions critical for normal EGFR activation, the intermolecular EGFR activation interface and the activation loop. Residue R958 falls between helices H and I and is proximal to the intermolecular EGFR activation interface recently revealed by structure directed studies.
Residue E884 is the conserved glutamate of the MALE motif and falls within helix EF at the Cterminus of the activation loop. This salt bridge helps orientate helix EF. In the recent EGFR kinase domain crystal structure bound to a peptide substrate analogue , helix EF packs against the substrate analogue suggesting that disruption of the salt bridge by an acquired E884K mutation could influence substrate recognition and binding. The acquisition of a lysine at codon 884 may therefore bring about local conformation disruptions that alter EGFR interactions with downstream substrates. Although we did not identify further E884K mutation in EGFR from the Japanese patients tumor sample cohort, the results of our study may have implication on the potential impact of cancer associated mutations that may interrupt the integrity of the salt bridge of a kinase.
Since the human kinome is a rich source of druggable targets, we extended our search through bioinformatics data mining from the COSMIC human cancer genome re sequencing project. To this end, we identified several proximal ion pair residue substitutions recorded in the COSMIC database at the E884 homologous residue, in the oncogenic kinases KIT, and RET, as well as in the tumor suppressor gene LKB1. Mutations at the neighboring residues of the conserved motif MAPE, as exemplified in FAK A612V, MET M1268I T.

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