title: Identification of hypoxia-induced genes in a malignant glioma cell line (U-251) by cDNA microarray analysis.
abstract: Overcoming the metabolic restrictions of hypoxia may allow the progression of lower-grade tumors to glioblastoma multiforme. Our findings of up-regulation of HIF-1alpha and its downstream targets VEGF, GLUT-1, and CAIX in higher-grade gliomas support this hypothesis. We compared the gene expression profiles of the U-251 malignant glioma cell line under normoxic and hypoxic conditions to discover future research targets. U-251 cells were grown to 75% confluence and exposed to either normoxic or hypoxic conditions for 24 h. RNA was extracted, amplified, and hybridized to a cDNA microarray chip containing ~8,800 universal cellular genes. A threefold increase in mRNA expression was used as a threshold value for differential expression. Identified genes were divided into cell cycle control, stress response, and "newly connected" genes. Hybridization identified 11 hypoxia-induced genes: 1 involved with cell cycle control (CCNG2), 6 in stress response (IGFBP3, SLC2A3, GSTT2, FOS, DDIT3, AKR1C3), and 2 newly connected genes (Depp, AKAP4). One stress-related gene (AKR1C3) encodes for an enzyme that synthesizes progesterone. Of newly connected genes, the gene decidual protein induced by progesterone (Depp) showed the highest expression (4.2-fold increase). Possible future targeting for "hypoxic" glioma cells includes the targets for the AP-1 transcription factor complex (FOS), as well as blockade of the enzyme AKR1C3 with nonsteroidal anti-inflammatory drugs. Possible functions of the highly expressed gene Depp include tumor vascularization. Future studies will focus on the hypothesis that Depp is up-regulated in an autocrine fashion by the AKR1C3 enzyme in U-251 glioma cells under hypoxic conditions.
authors.affiliation: Department of Neurosurgery, University of Utah, Salt Lake City, UT 84132, USA.
authors.forename: Brian T
authors.initials: BT
authors.lastname: Ragel
authors.forename: William T
authors.initials: WT
authors.lastname: Couldwell
authors.forename: David L
authors.initials: DL
authors.lastname: Gillespie
authors.forename: Randy L
authors.initials: RL
authors.lastname: Jensen
mesh_terms: D001932:Brain Neoplasms / Q000235:genetics*; D015687:Cell Hypoxia / Q000235:genetics / Q000502:physiology; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D016207:Cytokines / Q000096:biosynthesis / Q000235:genetics; D004249:DNA Damage; D018076:DNA, Complementary / Q000235:genetics*; D004273:DNA, Neoplasm / Q000235:genetics*; D005910:Glioma / Q000235:genetics*; D051272:Glucose Transporter Type 1 / Q000096:biosynthesis / Q000235:genetics; D006801:Humans; D000860:Hypoxia / Q000235:genetics*; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000096:biosynthesis / Q000235:genetics; D036341:Intercellular Signaling Peptides and Proteins / Q000096:biosynthesis / Q000235:genetics; D009693:Nucleic Acid Hybridization; D020411:Oligonucleotide Array Sequence Analysis; D012334:RNA, Neoplasm / Q000096:biosynthesis / Q000235:genetics / Q000302:isolation & purification; D013312:Stress, Physiological / Q000235:genetics; D015854:Up-Regulation / Q000235:genetics; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis / Q000235:genetics
chemical_list: D016207:Cytokines; D018076:DNA, Complementary; D004273:DNA, Neoplasm; D051272:Glucose Transporter Type 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D036341:Intercellular Signaling Peptides and Proteins; D012334:RNA, Neoplasm; D042461:Vascular Endothelial Growth Factor A