EXPRESSION OF PLATELET-DERIVED GROWTH-FACTORS, TRANSFORMING GROWTH-FACTORS, AND THE ROS GENE IN A VARIETY OF PRIMARY HUMAN BRAIN-TUMORS

Ribonucleic acid was isolated from a wide spectrum of central nervous system tumors to examine the expression of platelet-derived growth factors (PDGF) A and B, tumor growth factors (TGF-beta) 1 and 2, and ros messenger ribonucleic acid. Eight glioblastoma cell lines were examined as well as cell cultures from 22 tumor explants. The explants included 6 glioblastomas, 4 anaplastic astrocytomas, 5 astrocytomas, 3 ependymal tumors, 2 meningiomas, 1 medulloblastoma, and 1 ganglioglioma. For comparison, 2 nontumor glial cell cultures were included. The PDGF B-chain was expressed in 5 of 8 glioblastoma cell lines, 2 of 6 glioblastomas, and in 3 of 4 anaplastic astrocytoma explants. There was no PDGF B expression in 4 astrocytomas, 3 ependymomas of varying malignancy, in the remainder of the tumors, or in the nontumor glial cells. The PDGF A-chain was expressed in all of the tumors, with the exception of the malignant ependymoma and in both nontumor glial cell cultures. TGF-beta-1 was expressed in all of the tumors and in nontumor glial cells. The expression of TGF-beta-2 was expressed in many of the benign and malignant tumors and also in both nontumor glial cell cultures. The ros messenger ribonucleic acid was expressed in 1 of 5 glioblastoma cell lines and in 2 of 6 glioblastoma cell explants, but in none of the other tumors or in the nontumor glial cells. Thus, messenger ribonucleic acids of both PDGF B, with homology to the simian sarcoma virus sis gene, and the ros gene, which codes for a protein with a structure similar to the epidermal growth factor and insulin receptor, are expressed in some of the most malignant glial cell tumors but not in more benign tumors or in nontumor glial cells. They may play an important role in the initiation or maintenance of the malignant phenotype. TGF-beta-1, TGF-beta-2, and PDGF A are unlikely to be involved in this conversion.