The effect of prolactin and bombesin on the growth of meningioma-derived cells in monolayer culture.

Meningioma growth is thought to be stimulated by the sex hormones progesterone and possibly estrogen. We report here stimulation of growth of meningioma-derived cells in culture by prolactin. Fourteen human tumors taken from surgery were initially grown in Ham's medium F10 with 15% fetal calf serum. The tumors were then trypsinized and resuspended in medium in a multi-well plate with either prolactin or bombesin; the cells were incubated for 1 week, washed, and resuspended for cell counting. The growth-stimulating effect of prolactin at 10 and 200 micrograms/ml was compared with bombesin at 5 mM/ml or 15 mM/ml. A growth index compared cell count in the experimental well to the control well; growth at the rate of the control well was given an index of 1.0. The tumors included 7 meningiomas and 7 other neoplasms (3 astrocytomas, an ependymoma, a pineoblastoma, a hemangiopericytoma, and a metastatic adenocarcinoma). For meningiomas incubated in 10 micrograms/ml prolactin, the growth index was 3.08; for those incubated in 200 micrograms/ml prolactin, it was 2.28. Bombesin indices were 1.7 and 1.2 at 5 mM/ml and 15 mM/ml, respectively. By 2-tailed t-testing both prolactin concentrations stimulated the growth of meningiomas significantly (P < or = 0.02), while bombesin did not. Neither peptide enhanced the growth of the other tumors tested.