Calcium channel antagonist effect on in vitro meningioma signal transduction pathways after growth factor stimulation.

OBJECTIVE: We have previously demonstrated that calcium channel antagonists inhibit the growth of human meningiomas in culture after stimulation with growth factors. This study examined the effects of these drugs on signaling transduction pathways in an attempt to elucidate potential mechanisms by which this growth inhibition is mediated.
METHODS: Primary cell cultures from patients with intracranial meningiomas were established. Cell growth studies were performed with inhibitors and stimulators of tyrosine kinase signal transduction. Intracellular calcium changes and inositol phosphate production were measured after growth factor exposure, with or without pretreatment by calcium channel antagonists.
RESULTS: The growth of meningiomas in culture can be inhibited by tyrosine kinase receptor inhibitors. Inhibitors and stimulators of phospholipase C can stimulate or inhibit the growth of in vitro meningiomas, respectively. Calcium channel antagonists inhibit intracellular calcium changes induced by serum and epidermal growth factor. Inositol phosphate production is increased after growth factor stimulation, and calcium channel antagonists potentiate this effect.
CONCLUSION: Calcium channel antagonists interfere with intracellular signaling pathways of cultured meningioma cells. This inhibition is unrelated to voltage-sensitive calcium channels. The findings of this project may aid in the understanding of the signal transduction mechanisms involved in growth factor-mediated meningioma proliferation and may lead to clinically relevant strategies for growth inhibition.