Charaterization Of A New EGFR Antibody And Function Research

Dysfunction of the epidermal growth factor receptor(EGFR) family, is the key process in tumorigenesis,and anti-EGFR therapeutic strategies such as cetuximab therapy now are used in the treatment of cancer with EGFR positive.However, the exact mechanism how the Antibodies against EGFR act as a candidate of cancer therapy has not been elucidated.Here, we launch a screen of a phage display library to isolate more than 400 novel anti-EGFR antibody,one of them,named YAH627, shows the best cell proliferation inhibition performance,even better than cetuximab.Moreover, we use epitope analysis validates that the epitope of this antibody is within domains II and IV of EGFR and traps EGFR in a silent conformation.Next,we prove that YAH627 exhibits superior efficacy in inhibiting cancer cell line proliferation can block EGF/HRG-induced EGFR/HER3 heterodimerization and signaling by Co-IP.In the EGFR homodimer structure,EGFR residues Y246 and Y251 interact across the dimer interface with R285 and F263. In our data, Y246 and Y251, which also located at the YAH627 epitope, were mutated to alanine with significant effect on EGFR/HER3 heterodimerization. Thus, our mutagenesis suggests that formation of EGFR/HER3 heterodimer may be also dependent on correct contacts with the dimerization arm as the structural observation in the EGFR homodimer.Our experiments in cell signaling and growth show that using cetuximab to block the ligand is no more efficient than directly inhibiting the formation of the dimers with YAH627 treatment, a treatment producing a mechanism similar to that of the anti-HER2 antibody pertuzumab,which binds to the domain II of HER2.Moreover,combining YAH627 with cetuximab produces synergistic antitumor activity in vitro and in vivo. Taken together, our report establishes that YAH627 possesses a novel mechanism of action that, in combination with cetuximab, may achieve clinical efficacy in EGFR-driven cancers.