Elevated expression of basic fibroblast growth factor messenger ribonucleic acid in acoustic neuromas

Human tumors were analyzed for the presence of mRNA coding for basic fibroblast growth factor (basic FGF). Basic FGF transcript levels were consistently elevated in schwannoma samples (five acoustic neuromas and two spinal schwannomas) ranging from 9- to 22-fold higher than the average level of expression in four benign meningioma samples. Acidic extracts of acoustic neuromas contained a potent mitogen which bound to heparin-Sepharose, eluted at 2 M NaCl, and cross-reacted with an N-terminal specific anti-basic FGF antiserum. The present findings indicate that basic FGF appears to be the major heparin-binding endothelial cell mitogen in acoustic neuromas. Southern restriction analysis revealed no evidence of amplification or rearrangement of the gene for basic FGF in schwannomas or in the astrocytoma cell line U87-MG. These findings demonstrate a tumor-specific elevation in basic FGF transcript levels in tumors of Schwann cell origin and suggest that increased transcription or stabilization of basic FGF mRNA may play an autocrine role in the development and progression of these tumors.