Gene expression abnormalities in human glial tumors identified by gene array

Novel genes specific for human oligodendroglioma and glioblastoma multiform e (GBM) were detected using the gene array analysis [18,376 genes Gene Disc overy Array (GDA) from Incyte Genomics, Inc.]. Eleven genes were; chosen ba sed on the highest ratios of differential expression identified by GDA betw een histologically normal adjacent tissue and brain tumor tissue. The diffe rential expression of those 11 genes was verified by semiquantitative RT-PC R and Northern analysis on 22 samples of glial and other tumors of the brai n, as well as of normal embryonic and adult brain tissue. Gene #5 (an EST) was more expressed by GDA analysis in histologically normal adjacent brain tissue than in the corresponding oligodendroglioma. By RT-PCR, this gene wa s expressed in a number of brain tumors but not in normal adult and embryon ic brain. By GDA analysis, gene #7 (oligophrenin-1) gave the highest ratio compared to other genes in brain tissue adjacent to the GEM vs. GEM. By RT- PCR, oligophrenin-1 was expressed in tumors and tumor adjacent tissue, wher eas meningioma and corpus callosum were negative. Gene #11 (an EST) was exp ressed only in brain tumors but not in normal brain by Northern analysis (m essage size 1.5 kb) and RT-PCR. GDA analysis successfully identified genes preferentially expressed in brain tumors, which was confirmed by Northern a nalysis and semiquantitative RT-PCR. The validity of gene arrays fdr tumor- specific gene discovery is discussed. Study of differential gene expression in glial tumors should help identify the mechanism/s of transformation of normal glial cells to malignant.