Reactivation of insulin-like growth factor binding protein 2 expression inglioblastoma multiforme: A revelation by parallel gene expression profiling

We carried out a gene expression profiling study using cDNA array technolog y with 24 primary glioma tissues of low-grade (oligodendroglioma), intermed iate-grade (anaplastic oligodendroglioma and anaplastic astrocytoma), and h igh-grade (glioblastomas multiforme) tumors and found that insulin-like gro wth factor binding protein 2 (IGFBP2) was consistently overexpressed only i n glioblastoma multiforme. The cDNA array results were confirmed by Norther n and Western blotting. The fact that the IGFBP2 gene, which is normally ex pressed in fetal cells and turned off in adult cells, becomes reactivated i n the most advanced stage of glioma suggests that glioma progression is a r esult of dedifferentiation or results from a block of differentiation. Iden tification of IGFBP2 as a gene associated with glioma progression demonstra tes the power and utility of high-throughput gene expression profiling in c ancer gene discovery.