ANTICANCER DRUG DISCOVERY THAT TARGETS TUMOR HYPOXIA

描述(由申请人提供)：拟议研究的目标是识别和表征肿瘤缺氧的小分子天然产物衍生调节剂。实体肿瘤包含处于低氧压(缺氧)下的区域，这种缺氧导致对放射治疗和化疗的抵抗。低氧相关的治疗抵抗可直接通过降低细胞内氧浓度或间接通过低氧诱导的基因表达改变而产生。目前克服缺氧的努力针对的是缺氧的直接影响。我们提出了一种新的方法，专门针对缺氧(肿瘤基因表达的改变)这一重要的间接影响。 该计划的独特重点是识别和评估以低氧诱导的基因表达为靶点的天然产物衍生小分子。将采用天然产物化学和分子生物学相结合的三管齐下的方法来识别和研究这种小分子。第一个目标将涉及分离和确定天然产物衍生的肿瘤缺氧调节剂的化学结构。这类调节剂将针对低氧肿瘤细胞特有的一些过程，这些过程是肿瘤细胞适应低氧的关键。已经建立了一个高通量生物检测小组来识别这样的调节者。活性化合物将通过生物测定引导的分离和分离来分离，并使用光谱和光谱方法相结合的方法来阐明它们的化学结构。我们小组已经通过初步研究确定了几种有效的新的缺氧诱导因子-1(HIF-1)抑制剂，从而为这一方法建立了原理证据。缺氧诱导因子-1(HIF-1)是一种关键的转录因子，在低氧条件下激活生存基因的表达。第二个目标将确定受新发现的活性导联影响的靶基因。初步研究表明，天然产物衍生的小分子可以选择性地抑制HIF-1的缺氧性激活，也可以抑制HIF-1的缺氧性和化学激活，这取决于每种抑制剂的特定化学类别。抑制HIF-1的激活与减少缺氧诱导的HIF-1靶基因血管内皮生长因子(VEGF)有关，而血管内皮生长因子是肿瘤血管生成的有力启动者。目标基因将通过微阵列分析进行鉴定。第三个目标将集中于新发现的活性天然产物调节低氧信号的机制的生化和细胞生物学研究。完成这些目标将提供针对肿瘤缺氧的药物先导和分子探针，并为研究受这些分子影响的细胞内途径提供新的见解。

DESCRIPTION (provided by applicant): The objective of the proposed research is to identify and characterize small molecule natural product-derived regulators of tumor hypoxia. Solid tumors contain regions under low oxygen tension (hypoxia) and this lack of oxygen contributes to resistance to radiation treatment and chemotherapy. Hypoxia-associated treatment resistance can be caused directly through reduced cellular oxygen concentrations or indirectly through hypoxia-induced modifications in gene expression. Current efforts to overcome hypoxia target the direct effects of hypoxia. We propose a new approach that specifically targets this important indirect effect of hypoxia (alteration of tumor gene expression). The unique focus of this program is to identify and evaluate natural product-derived small molecules that target hypoxia-induced gene expression. A three-pronged approach that combines natural products chemistry with molecular biology will be employed to identify and investigate such small molecules. The first objective will involve isolating and determining the chemical structures of natural product-derived regulators of tumor hypoxia. Such regulators will target a number of processes that are unique to hypoxic tumor cells and key for tumor cell adaptation to hypoxia. A panel of high-throughput bioassays has been established to identify such regulators. Active compounds will be isolated through bioassay-guided fractionation and isolation, and their chemical structures elucidated using a combination of spectroscopic and spectrometric methods. Our group has established the proof of principle for this approach through preliminary research that has identified several potent new hypoxia inducible factor-1 (HIF-1) inhibitors. HIF-1 is a key transcription factor that activates the expression of survival genes under hypoxia. The second objective will identify target genes affected by newly identified active leads. Preliminary studies have revealed that natural product derived small molecules can either selectively inhibit hypoxic activation of HIF-1 or inhibit both hypoxic and chemical activation of HIF-1, depending upon the specific chemical class of each of inhibitor. Inhibition of HIF-1 activation is associated with reduction of the hypoxic induction of HIF-1 target gene vascular endothelial growth factor (VEGF), a potent initiator of tumor angiogenesis. Target genes will be identified by microarray analysis. The third objective will focus on biochemical and cell biological investigations of the mechanisms by which newly identified active natural products regulate hypoxic signaling. Accomplishing these objectives will provide drug leads and molecular probes that target tumor hypoxia and afford new insights into the intracellular pathways affected by these molecules.