Effect of nerve growth factor producing cells on anaplastic glioma and pheochromocytoma clones: involvement of other factors.

When the NGF-secreting C-6 rat glioma cells were intracerebrally injected with F98 rat anaplastic glioma cells into rats syngeneic for the F98 cells, an increased mean survival time was observed for rats developing tumors compared with those injected with only anaplastic glioma cells. Thirty percent of the rats injected with both cell types showed no signs of tumor at 90 days. Pretreatment of the anaplastic glioma cells with conditioned medium of C-6 cells did not duplicate these results unless the C-6 cells were pretreated with 17 beta-estradiol, which appears to induce secretion of an adhesion factor as well as NGF. These rats survived even longer and 33% were free of tumors at 90 days. Histological examination of tumors of the nonsurviving rats revealed that they were basically well differentiated with only small anaplastic areas remaining. Both NGF and conditioned medium from C-6 and another NGF-secreting line, S-180 mouse sarcoma, induce process formation in F98 cells and in PC12 pheochromocytoma cells, but the processes that appear following NGF exposure are morphologically different from those induced by conditioned medium. Conditioned -medium-treated cells also have a flatter appearance. In F98 cells, NGF takes longer to induce processes than does conditioned medium. The NGF-induced effects observed in both cells are neutralized by anti-NGF IgG, but those induced by conditioned media are not. Nerve growth factor (NGF) induced increased adhesiveness in F98 rat anaplastic glioma and PC12 rat pheochromocytoma cells. Conditioned media are not. Nerve growth factor induced increased adhesive-and PCuced effects observed in both cells are neutralized by anti-NGF IgG, but those induced by conditioned media are not. Nerve growth factor (NGF) induced increased adhesiveness in F98 rat anaplastic glioma and PC12 rat pheochromocytoma cells. Conditioned media are not. Nerve growth factor induced increased adhesive-and PCuced effects observed in both cells are neutralized by anti-NGF IgG, but those induced by conditioned media are not. Nerve growth factor (NGF) induced increased adhesiveness in F98 rat anaplastic glioma and PC12 rat pheochromocytoma cells. Conditioned media are not. Nerve growth factor induced increased adhesive-and PC12 cells. Anti-NGF IgG did not influence this effect on F98 cells and only partially neutralized the effect on PC12 cells, indicating that other factors may be operative in this system. Conditioned medium collected from C-6 cells pretreated with 17 beta-estradiol induced the highest degree of adhesiveness observed in both F98 and PC12 cells, and this action was unaffected by anti-NGF IgG in either case. Conditioned media from other cell lines, a variety of selected proteins, and dBcAMP did not induce increased adhesiveness. The factor responsible for this effect is nondialyzable, heat-sensitive, and ammonium-sulfate-precipitable, and its secretion appears to be stimulated by 17 beta-estradiol.