Ragel Brian T, Couldwell William T, Gillespie David L, Jensen Randy L
Department of Neurosurgery, University of Utah, Salt Lake City, UT 84132, USA.
Neurosurg Rev. 2007 Jul;30(3):181-7; discussion 187. doi: 10.1007/s10143-007-0070-z. Epub 2007 May 8.
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.
克服缺氧的代谢限制可能会使低级别肿瘤进展为多形性胶质母细胞瘤。我们在高级别胶质瘤中发现缺氧诱导因子-1α（HIF-1α）及其下游靶点血管内皮生长因子（VEGF）、葡萄糖转运蛋白1（GLUT-1）和碳酸酐酶IX（CAIX）上调，支持了这一假说。我们比较了U-251恶性胶质瘤细胞系在常氧和缺氧条件下的基因表达谱，以发现未来的研究靶点。将U-251细胞培养至75%汇合度，然后分别置于常氧或缺氧条件下24小时。提取RNA，进行扩增，并与包含约8800个通用细胞基因的cDNA微阵列芯片杂交。将mRNA表达增加三倍作为差异表达的阈值。鉴定出的基因分为细胞周期调控、应激反应和“新关联”基因。杂交鉴定出11个缺氧诱导基因：1个与细胞周期调控有关（细胞周期蛋白G2，CCNG2），6个参与应激反应（胰岛素样生长因子结合蛋白3，IGFBP3；溶质载体家族2成员3，SLC2A3；谷胱甘肽S-转移酶T2，GSTT2；原癌基因FOS，FOS；DNA损伤诱导转录因子3，DDIT3；醛酮还原酶家族1成员C3，AKR1C3），以及2个新关联基因（蜕膜蛋白，Depp；A激酶锚定蛋白4，AKAP4）。一个与应激相关的基因（AKR1C3）编码一种合成孕酮的酶。在新关联基因中，孕酮诱导的蜕膜蛋白基因（Depp）表达增加最高（增加4.2倍）。未来针对“缺氧”胶质瘤细胞的可能靶点包括AP-1转录因子复合物的靶点（FOS），以及用非甾体抗炎药阻断AKR1C3酶。高表达基因Depp的可能功能包括肿瘤血管生成。未来的研究将聚焦于以下假说：在缺氧条件下，U-251胶质瘤细胞中，Depp通过AKR1C3酶以自分泌方式上调。
