IDENTIFICATION OF INSULIN-LIKE GROWTH-FACTOR (IGF) AND GLUCOSE TRANSPORTER-1 AND TRANSPORTER-3 MESSENGER-RNA IN CNS TUMORS

Glucose metabolism is increased in CNS tumors and correlates with mali gnant grade. We have previously investigated the role of IGFs in regul ating CNS tumor growth and metabolism. In the present study we examine d total cellular RNA from human CNS tumors for the presence for glucos e transporter (Glut) and IGF mRNA. Human meningiomas and gliomas were frozen in liquid nitrogen at the time of surgery and then stored at -8 0-degrees-C. Total cellular RNA was prepared by acid-guanidinium pheno l-chloroform extraction and 20 mug of RNA was loaded for agarose-forma ldehyde gel electrophoresis and transfer. RNA integrity in 5 meningiom as and 2 gliomas was confirmed by ethidium bromide staining of 28S and 18S ribosomal RNA and hybridization with a cDNA probe for beta-actin. For analysis, membranes were hybridized to radioactively labeled huma n Glut-1, Glut-3, IGF-I, and IGF-II cDNA probes, and mRNA transcripts were identified by autoradiography. All 7 tumors expressed Glut-I and Glut-3 mRNA and Glut-3 appeared to be more abundant in meningiomas. IG F-II mRNA was detected in 2 of 6 meningiomas and in both gliomas. IGFs may play an important role in the regulation of glucose metabolism in CNS tumors. IGFs and specific glucose transporters may prove useful a s markers of malignancy and potential targets for future therapy.