Human acoustic neuromas secrete interleukin-6 in cell culture: possible autocrine regulation of cell proliferation.

Interleukin-6 (IL-6) secretion by cell cultures of human acoustic neuromas was examined. Secretory rates varied from 0.02 to 5.4 ng/10(5) cells per 4 days, depending on the tumor. The IL-6 immunoreactivity eluted from a Sephadex G-100 column in a major peak corresponding to an M(r) of 30,000 and a lesser peak corresponding to an M(r) of 50,000. Western blot analysis revealed three IL-6 immunoreactive bands with M(r)s corresponding to 53,000, 29,000, and 24,000. Tumor necrosis factor-alpha, interleukin-1-beta, and cholera toxin all stimulated IL-6 secretion. An antisense phosphorothioate oligonucleotide against IL-6 messenger RNA inhibited both [3H]thymidine uptake and IL-6 secretion by acoustic neuroma cells in culture. In addition, [3H]thymidine uptake was inhibited by a specific polyclonal antibody against IL-6. We conclude that human acoustic neuroma cells produce and secrete IL-6, which may act in an autocrine manner to stimulate cellular proliferation.