Differential immunoscreening identifies a glycosylation variant of the epidermal growth factor receptor in ME-180 cervical carcinoma cells.
In this report, we describe the development and characterization of an anti-ME-180 cervical cancer-specific epidermal growth factor (EGF) receptor monoclonal antibody (MAb). This MAb, 6C7, specifically binds to ME-180 cervical cancer cells and not to normal cervical epithelial cells. By immunoaffinity chromatography, we have shown that the 6C7 antibody binds to a 205-kDa protein. Subsequent mass spectrometry sequencing analysis identified this protein as an EGF receptor. In addition, treatment of the ME-180 EGF receptor with N- and O-linked glycosidases indicated that this antibody binds to the carbohydrate portion of the glycoprotein. Moreover, Western blotting analysis with an anti-EGF receptor antibody indicated that this protein is present in abundance in all cervical cancer cell lines, including ME-180, HeLa, Ca Ski, HT-3, SiHa, and Hs 588.T. However, the 6C7 antibody only binds to the EGF receptor from ME-180 cells, suggesting that this protein is differentially glycosylated in ME-180 cells, compared to other cervical cancer cell lines. Finally, we have shown that this antibody could selectively block EGF-mediated cell proliferation in ME-180 cells but not in HeLa cells. Overall, our study suggests that the differentially glycosylated EGF receptor could potentially serve as a unique target for the immunotherapeutic treatment of cervical cancer.