High Incidence of Somatostatin Receptors in Human Meningiomas: Biochemical Characterization

Thirteen human meningiomas were tested for their content of specific somatostatin (SRIH) receptors using an in vitro binding assay with meningioma homogenates as well as receptor autoradiography. All tumors had measurable amounts of somatostatin receptors. Receptor density, however, greatly varied among the tumors, ranging from low levels to more than 400 fmol/mg protein. Seven tumors, biochemically characterized in detail, had saturable and high affinity receptors [mean Kd, 1.10 +/- 0.42 (+/- SEM) nM], with pharmacological specificity for SRIH resembling the noncentral nervous system type of SRIH receptor. There was no correlation between the density of SRIH receptors and the density of progestin receptors measured in parallel. The presence of SRIH receptors in meningiomas was completely unexpected, and their role unknown. If the receptors can mediate antiproliferative properties in meningiomas, as has been suggested to be the case for such receptors in other endocrine tumors, the present data could be of potential therapeutic interest.