2014 Volume 77 Issue 2 Pages 59-65
Cetuximab, a specific anti-EGFR monoclonal antibody, is used in cancer treatment. Although development of resistance to cetuximab is well recognized, the underlying mechanisms remain unclear. In the present study, we characterized cetuximab-resistant oral squamous cell carcinoma (OSCC) cell lines. The human OSCC cell lines HSC3, HSC4, and SAS were studied to identify the characteristics of cell resistant to cetuximab. Cetuximab inhibited proliferation of HSC3 and HSC4 cells, but not SAS cells. Proliferation of all three cell lines was inhibited by the EGFR/ErbB2/ErbB4 inhibitor II. The EGFR inhibitor AG1478 strongly inhibited HSC3 and HSC4 proliferation, but inhibited SAS cells only moderately. EGFR proteins were localized on the cell surface and phosphorylated in all three cell lines. Thus, cetuximab-resistant SAS cells still expressed EGFR in the cell membrane and EGFR became phosphorylated when stimulated with a ligand.
