Oncogene-related growth factors and growth factor receptors in human malignant glioma-derived cell lines.

Oncogenes induce malignant transformation of cells. Two oncogenes are closely related to genes coding for a mitogenic growth factor (v-sis to the PDGF gene) and a receptor for a mitogenic growth factor (v-erb B to the EGF receptor gene). We studied the possibility that cells derived from malignant gliomas produce mitogenic factors that bind to cell surface receptors, the activation of which could lead to excessive stimulation of cell proliferation. All six cell lines tested secrete into their medium factors that stimulate DNA synthesis. The factor secreted by one cell line was characterized and found to resemble PDGF. Six of 11 cell lines had receptors for PDGF demonstrable by binding and receptor autophosphorylation assays. Six of six cell lines tested had EGF receptors demonstrable by binding and receptor autophosphorylation experiments. The extremely high levels of EGF receptor in one cell line may reflect excessive expression of the erb B oncogene associated with abnormalities of chromosome 7 that occur in this cell line.