Analysis of c-erbB2 protein content of human glioma cells and tumor tissue.

This study was designed to determine whether or not overexpression of the c-erbB2 protein plays a role in the etiology of human gliomas. The c-erbB2 gene codes for a 185 kDa cell membrane glycoprotein (gp185c-erbB2), 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 gp185c-erbB2, using immunofluorescence microscopy, immunoblot analysis and flow cytometry. A-172 cells were found to have the highest content of gp185c-erbB2. More detailed studies utilizing A-172 cells indicated that cellular gp185c-erbB2 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 gp185c-erbB2 fluorescence and DNA content, using A-172 cells as a biological standard. Results indicated that gp185c-erbB2 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 the molecular heterogeneity of human gliomas and indicate that gp185c-erbB2 may have a role in at least a subset of malignant glial tumors.