Study Of EGFR Family Overexpression Carcinogenesis Mechanism And The Mechanism Of Drug Action

Epidermal growth factor receptor family(EGFRs),the member of the tyrosine kinase receptor family(RTKs),has EGFR/HER2/HER3/HER4 four members.EGFR and HER4 have intact ligand binding domains and kinase domains,however HER2 does not have the ability to bind ligands and the kinase domain of HER3 is inactivity.Aberrant expression of EGFRs can lead to abnormal activation of downstream signaling pathways,leading to cancer.Currently,in the therapy of various cancers such as lung cancer and breast cancer,EGFR and HER2 receptors have become important drug targets.Anti-cancer drugs targeting EGFR and HER2 receptors mainly include small molecule kinase inhibitors and macromolecular antibody drugs,which act on the kinase domain and extracellular domain of the receptor,respectively,leading to the phosphorylation inhibition of the receptor.And they can be jointly used to solve drug resistance problems because of the different action sites.However,the mechanism of signal transduction from the extracellular domain to the intracellular kinase domain remains unclear.Studies have shown that the activation of EGFRs requires the formation of asymmetric dimers of the kinase domains.Therefore,we have established the split YFP complementation system to study the effects of drugs on EGFR/HER2 kinase dimer formation.In this experiment,we used YFP as the fluorescent protein in BiFC technology.We added YFP-N and YFP-C protein fragments to the C-terminus of EGFR and HER2,and indirectly reflected EGFR/HER2 heterodimer by detecting YFP signals.We found that the small molecule kinase inhibitors Gefitinib,Lapatinib,and the macromolecular antibody drug Herceptin all promote the formation of EGFR/HER2 heterodimer,simultaneously EGFR/HER2 dimers all showed an increasing trend when treated with Gefitinib combined with Herceptin,and Lapatinib combined with Herceptin.Through the validation of a fluorescent probe C3P3 that targets EGFR for EGFR inhibition and screenability,we found that the C3P3 probe has stronger binding to the mutant EGFR while inhibiting the phosphorylation of EGFR,and the application of C3P3 provides a new idea for tumor-specific markers.