[Pharmacology and signaling properties of EGFR isoforms studied by Bioluminescence Resonance Energy Transfer (BRET).]
>>Mol Pharmacol. 2006 Sep 12; [Epub ahead of print]
Pharmacology and signaling properties of EGFR isoforms studied by Bioluminescence Resonance Energy Transfer (BRET).
Schiffer HH, Reding EC, Fuhs SR, Lu Q, Piu F, Wong S, Littler PL, Weiner DM, Keefe W, Tan PK, Nash NR, Knapp AE, Olsson R, Brann MR.
ACADIA Pharmaceuticals.
We have developed a new assay for measuring epidermal growth factor receptor (EGFR) activation using the bioluminescence-resonance-energy-transfer (BRET) technology, which directly measures the recruitment of signaling proteins to activated EGFR. Our results demonstrate that EGFR BRET assays precisely measure the pharmacology and signaling properties of EGFR expressed in HEK293T cells. EGFR BRET assays are highly sensitive to known EGFR ligands (pEC50 EGF = 10.1 +/- 0.09), consistent with previous pharmacological methods for measuring EGFR activation. We applied EGFR BRET assays to study the characteristics of somatic EGFR mutations that were recently identified in lung cancer. In agreement with recent reports, we detected constitutively active mutant EGFR isoforms, which predominantly signal through the PI3K/Akt pathway. The EGFR inhibitors Iressa or Tarceva are several folds more potent in inhibiting constitutive activity of mutant EGFR isoforms compared to wild type EGFR. Notable, our results reveal that most of the mutant EGFR isoforms tested were significantly impaired in their response to EGF. The highest level of constitutive activity and nearly complete loss of EGF responsiveness was detected in isoforms, which carry the activating mutation L858R and the secondary resistance mutation T790M. In summary, our study reveals that somatic mutation in EGFR quantitatively differ in pharmacology and signaling properties, which suggest the possibility of differential clinical responsiveness to treatment with EGFR inhibitors. Furthermore, we demonstrate that the EGFR BRET assays are a useful tool to study the pharmacology of ligand-induced interaction between EGFR and signaling pathway specifying adapter proteins.<<
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This is interesting, but this area is not what I think of as Acadia's core competency. If it's worth something, I would expect them to out-license it. Question is, is it worth something? Were the fuzzy relationships of patients' EGFR expression to their responses to EGFR inhibitors the results of inferior assays, or some aspect of the pharmacology we don't yet understand? If the latter, the tests aren't worth much; if the former, this one could be worth plenty.
Anyone got thoughts?
Cheers, Tuck |
