ANTICANCER DRUG DISCOVERY THAT TARGETS TUMOR HYPOXIA

描述（由申请人提供）：拟议研究的目的是鉴定和表征小分子天然产物衍生的肿瘤缺氧调节剂。实体瘤包含低氧张力（缺氧）的区域，这种缺氧会导致对放射治疗和化疗的抵抗。缺氧相关的治疗抵抗可以通过细胞氧浓度降低直接引起，也可以通过缺氧诱导的基因表达改变间接引起。目前克服缺氧的努力主要针对缺氧的直接影响。我们提出了一种新方法，专门针对缺氧的这种重要的间接影响（肿瘤基因表达的改变）。 该计划的独特重点是识别和评估针对缺氧诱导基因表达的天然产物衍生小分子。将采用将天然产物化学与分子生物学相结合的三管齐下的方法来识别和研究此类小分子。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。此类调节剂将针对缺氧肿瘤细胞特有的许多过程，这些过程是肿瘤细胞适应缺氧的关键。已经建立了一组高通量生物测定法来识别此类调节剂。将通过生物测定引导的分馏和分离来分离活性化合物，并结合光谱和光谱测定方法来阐明其化学结构。我们的小组通过初步研究确定了这种方法的原理证明，并确定了几种有效的新型缺氧诱导因子 1 (HIF-1) 抑制剂。 HIF-1是在缺氧条件下激活生存基因表达的关键转录因子。第二个目标将确定受新发现的活性先导化合物影响的靶基因。初步研究表明，天然产物衍生的小分子可以选择性抑制 HIF-1 的缺氧激活，或者同时抑制 HIF-1 的缺氧和化学激活，具体取决于每种抑制剂的具体化学类别。 HIF-1 激活的抑制与 HIF-1 靶基因血管内皮生长因子 (VEGF) 的缺氧诱导减少相关，VEGF 是肿瘤血管生成的有效引发剂。靶基因将通过微阵列分析来鉴定。第三个目标将侧重于新发现的活性天然产物调节缺氧信号传导机制的生化和细胞生物学研究。实现这些目标将提供针对肿瘤缺氧的药物先导物和分子探针，并为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.