Effects of transforming growth factor-beta1 and basic fibroblast growth factor on proliferation of cell cultures derived from human vestibular nerve schwannoma.

The influence of transforming growth factor-beta1 (TGF-beta1) and basic fibroblast growth factor (bFGF) on growth of cell cultures derived from unilateral vestibular nerve schwannomas was investigated. Cell cultures were initiated from 9 schwannomas and characterized immunocytochemically with antibodies against S-100 and type IV collagen. The effects of TGF-beta1 and bFGF on DNA synthesis in chemically defined serum-free medium were assessed by measuring the incorporation of 5-bromo-2'-deoxy-uridine (BRDU) into cellular DNA. Cell proliferation was evaluated with an electronic cell counter. Reverse transcription polymerase chain reaction (RT-PCR) was performed using oligonucleotide primers specific for TGF-beta1 and TGF-beta2. TGF-beta1 stimulated DNA synthesis in a dose dependent manner. Maximal stimulation was observed at a concentration of 1 ng/ml, which induced a nearly 2-fold increase in DNA content. This effect was not seen when TGF-beta1 was added in the presence of neutralizing antibodies. In addition, antibodies against TGF-beta1 significantly reduced DNA synthesis in control cultures without supplemented exogenous growth factors. bFGF alone had no significant effects on DNA synthesis. In contrast, when TGF-beta1 and bFGF were added together, the mitogenic response was much greater than produced by TGF-beta1 alone. RT-PCR showed that the cultured cells expressed mRNA for both TGF-beta1 and TGF-beta2. We hypothesize that TGF-beta1 is an autocrine growth factor for human vestibular nerve schwannomas in culture. A similar mechanism might be involved in the growth of these tumors in situ.

Laminin promotes differentiation, adhesion and proliferation of cell cultures derived from human acoustic nerve schwannoma.

The influence of laminin on cell cultures derived from unilateral acoustic nerve schwannomas was investigated. Cell cultures were initiated from 12 schwannomas, removed via the enlarged middle cranial fossa approach. Tumor tissue was dispersed by collagenase treatment and cells seeded in uncoated or laminin-coated culture dishes. Confluent cultures were immunocytochemically characterized with antibodies against S-100, CD 68, factor VIII-related antigen and type IV collagen. Cell adhesion in response to different doses of laminin was evaluated with an electronic cell counter. The effect of laminin on cell proliferation was assessed by measuring the incorporation of 5-bromo-2'-deoxy-uridine (BRDU) into cellular DNA. Cells cultured on laminin as substrate appeared more differentiated with long, fusiform, cytoplasmic processes. Cultured cells stained positive for S-100, not for factor VIII-related antigen or CD 68. Only cells cultured on laminin deposited a dense extracellular network of type IV collagen. When laminin was added to the culture medium, cell attachment and proliferation was stimulated in a dose dependent manner. Maximal stimulation of both was observed with a laminin concentration of 50 micrograms/ml, which induced a nearly 2-fold increase in cell attachment and an approximately 66% increase in DNA content. Since laminin is a major component of the extracellular matrix in schwannomas, the possibility exists that laminin is also mitogenic for human neoplastic Schwann cells in situ.