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Insulin
and insulin-like growth factor I in brain tumors: binding and in vitro effects
Glick RP, Gettleman R, Patel K, Lakshman R, Tsibris JC
Department of Neurosurgery, Cook County Hospital, Chicago, Illinois
We have measured insulin and insulin-like growth factor I (IGF-I) binding in
human gliomas, meningiomas, and normal brain and studied the effect of insulin
on the morphology, proliferation, and differentiation of central nervous system
tumor and normal fetal cells in culture.
Specific 125I-insulin and 125I-IGF-I binding was demonstrated by
competition-inhibition binding assays.
Insulin binding was measured in plasma membrane preparations from 9 freshly
isolated human meningiomas, 4 glioblastomas multiforme (GBMs), a low-grade
glioma, a normal adult brain, and a fetal brain.
IGF-I binding was measured in similar preparations from 5 meningiomas, 4 GBMs, a
low-grade glioma, and a normal adult brain.
Incubations were carried out at 4 degrees C for 18 to 20 hours.
Meningiomas showed higher specific insulin binding per 0.25 mg of protein than
GBMs (19% versus 3%, P less than 0.005), and this difference was not related to
small differences observed in insulin degradation.
By contrast, IGF-I binding was significantly higher in gliomas than in
meningiomas (27% versus 12%, P less than 0.05).
Also, IGF-I binding was significantly higher than insulin binding in GBMs (27%
versus 3%, P less than 0.03); binding of both IGF and insulin was high in
meningiomas.
In normal adult brain IGF-I and insulin binding was 7 to 10%.
The ability of insulin to support and enhance the growth of central nervous
system tumor cells in culture was investigated.
Cell cultures were derived from a freshly isolated glioblastoma, a low-grade
glioma, and 3 meningiomas.
(ABSTRACT TRUNCATED AT 250 WORDS)
PMID: 2546092 [PubMed - indexed for MEDLINE]
Source: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2546092&dopt=Abstract
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