Analysis of CerbB2 protein content of human glioma cells and tumor tissue

This study was designed to determine whether or not overexpression of the cerbB2 protein plays a role in the etiology of human gliomas. The cerbB2 gene codes for a 185 kDa cell membrane glycoprotein (gpl85cerbB2), which is similar to the receptor for epidermal growth factor. In initial studies, four human glioma cell lines (A-172, U118MG, U138MG and SW608) were used to develop techniques for detecting and quantifying gpl85cerbB2, using immunofluorescence microscopy, immunoblot analysis and flow cytometry. A-172 cells were found to have the highest content of gpl85cerbB2. More detailed studies utilizing A-172 cells indicated that cellular gpl85cerbB2 content changed little in response to conditions affecting cellular proliferative status, including serum deprivation, growth in low glucose medium and treatment with dimethyl sulfoxide. Ten human glioma specimens were then analyzed for cellular gpl85cerbB2 fluorescence and DNA content, using A-172 cells as a biological standard. Results indicated that gpl85cerbB2 was expressed at levels comparable to that of A-172 cells in many specimens, and at a very high level in one specimen. These data reiterate the problem of themolecular heterogeneity of human gliomas and indicate that gpl85cerbB2 may have a role in at least asubset of malignant glial tumors.