Radioimmunoassay of insulin-like growth factors I and II in the cerebrospinal fluid of patients with pituitary and other central nervous system tumors.

Abstract

Tumor cells are characterized by abnormalities in growth and metabolism, including the autocrine secretion of certain growth factors. On the basis of our previous demonstration of the production of insulin-like growth factors (IGFs) and their binding proteins by central nervous system (CNS) tumors, we asked whether the levels of IGFs in the CSF may be altered in patients with pituitary and other CNS tumors and may reflect autocrine secretion. We used specific radioimmuoassays for IGF-I and -II and measured these growth factors in the cerebrospinal fluid (CSF) from 26 patients with tumors located adjacent to the ventricular system. The tumors included were eight pituitary tumors (five nonsecreting, three growth hormone secreting), five gliomas, two meningiomas, five medulloblastomas, three metastases, and three other tumors. CSF from patients without tumors served as controls. For radioimmunoassay, CSF was treated with acetic acid overnight and IGF-binding proteins were separated from IGFs by C-2 solid phase cartridge extraction. The pituitary tumors were characterized by significantly elevated levels of IGFs in the CSF. In nonseceting pituitary tumors, the levels of IGF-I in the CSF were similar to normal levels, whereas IGF-II levels were significantly elevated. In acromegalic patients, levels of both IGF-I and -II in the CSF were significantly elevated compared with normal levels and compared with levels in patients with nonsecreting tumors. In contrast, the levels of IGFs in the CSF from most of the primary and metastatic CNS CNS tumors did not significantly differ from normal values. In summary, although IGFs may contribute to the regulation of cell growth in primary CNS tumors, CSF levels are not elevated.(ABSTRACT TRUNCATED AT 250 WORDS)