ANTICANCER DRUG DISCOVERY THAT TARGETS TUMOR HYPOXIA

描述（由申请人提供）：拟议研究的目的是发现、表征和验证小分子天然产物衍生的缺氧诱导因子-1（HIF-1）抑制剂作为癌症治疗的辅助药物。长期目标是开发专门针对肿瘤缺氧（低氧张力）的癌症化疗药物。实体瘤含有缺氧区域，缺氧的程度与恶性进展、对放射治疗和化学治疗的抗性以及疾病的复发相关。缺氧相关的治疗抗性可直接由细胞氧浓度降低引起，或间接由缺氧诱导的基因表达修饰引起。我们提出了一种新的方法，专门针对这种重要的缺氧间接影响（肿瘤基因表达的改变）。目前还没有批准的药物在临床上使用，专门针对缺氧。这个药物发现计划独特地将天然产物化学与尖端生物医学研究相结合。具体目标1将评估富含天然产物的提取物，分离和阐明抑制缺氧诱导和/或组成性激活的HIF-1的活性先导化合物的化学结构，HIF-1是在缺氧条件下激活适应和生存基因表达的主要转录因子。HIF-1不仅促进缺氧肿瘤的存活和转移，HIF-1的致癌激活也与恶性进展和治疗抗性相关。将在一组高通量生物测定中检查富含天然产物的提取物的HIF-1抑制活性（缺氧诱导和致癌激活）。活性化合物将通过生物测定引导的分离来分离，并且使用光谱和光谱方法的组合来阐明其结构。一些最有效的小分子HIF-1抑制剂的发现已经证明了原理。具体目标2将确定活性化合物对缺氧肿瘤细胞存活、血管生成和转移的影响。代表不同疾病阶段和缺氧反应性的一组肿瘤细胞系将用作体外模型。在体外抑制缺氧肿瘤细胞存活、血管生成和转移的无毒活性化合物将在基因工程小鼠乳腺癌模型中进一步研究。具体目标3将研究天然产物衍生的HIF抑制剂作为化疗剂的辅助剂的治疗潜力。目标是确定HIF-1抑制剂与化疗的最佳组合，可以实现抑制肿瘤生长的最大功效，同时具有低毒性。具体目标4将在分子和细胞水平上表征天然产物衍生的HIF抑制剂，并解决作用机制。实现这些目标将提供抗肿瘤药物线索和分子探针，将提供新的见解细胞内途径介导缺氧信号。公共卫生相关性：该项目与公共卫生高度相关，因为其目标是发现和开发治疗乳腺癌、前列腺癌和其他形式癌症的新药。这项研究的目的是发现肿瘤选择性小分子，这种小分子比目前大多数化疗药物的副作用和毒性都要小。这些化合物将针对肿瘤环境中的独特生理差异和肿瘤细胞中的特定遗传差异，使它们即使在缺氧的条件下也能存活和生长。

DESCRIPTION (provided by applicant): The objective of the proposed research is to discover, characterize, and validate small molecule natural product-derived hypoxia-inducible factor-1 (HIF-1) inhibitors as adjunct agents for cancer therapy. The long-term goal is to develop cancer chemotherapeutic agents that specifically target tumor hypoxia (low oxygen tension). Solid tumors contain hypoxic regions and the extent of hypoxia correlates with malignant progression, resistance to radiation treatment and chemotherapy, and relapse of the disease. Hypoxia-associated treatment resistance can be caused directly by reduced cellular oxygen concentrations or indirectly by hypoxia-induced modifications in gene expression. We propose a new approach that specifically targets this important indirect effect of hypoxia (alteration of tumor gene expression). There is no approved drug in clinical use that specifically targets hypoxia. This drug discovery program uniquely combines natural products chemistry with cutting edge biomedical research. Specific Aim 1 will evaluate natural product-rich extracts, isolate and elucidate the chemical structures of active leads that inhibit hypoxia-induced and/or constitutively activated HIF-1, the principle transcription factor that activates the expression of adaptation and survival genes under hypoxia. Not only does HIF-1 promote hypoxic tumor survival and metastasis, oncogenic activation of HIF-1 is also associated with malignant progression and treatment resistance. Natural product-rich extracts will be examined in a panel of high-throughput bioassays for HIF-1 inhibitory activities (hypoxia-induced and oncogenically activated). Active compounds will be isolated through bioassay-guided isolation, and their structures elucidated using a combination of spectroscopic and spectrometric methods. Proof of principle has been established by the discovery of some of the most potent small molecule HIF-1 inhibitors. Specific Aim 2 will determine the effects of active compounds on hypoxic tumor cell survival, angiogenesis, and metastasis. A panel of tumor cell lines that represent different disease stages and hypoxia responsiveness will be used as in vitro models. Nontoxic active compounds that inhibit hypoxic tumor cell survival, angiogenesis, and metastasis in vitro will be further investigated in genetically engineered murine breast cancer models. Specific Aim 3 will investigate the therapeutic potential of natural product-derived HIF inhibitors as adjunct agents with chemotherapeutic agents. The goal is to identify the optimal combination of HIF-1 inhibitors with chemotherapy that can achieve the maximum efficacy of inhibiting tumor growth with low toxicity. Specific Aim 4 will characterize natural product-derived HIF inhibitors at the molecular and cellular levels and resolve the mechanisms of action. Accomplishing these objectives will provide antitumor drug leads and molecular probes that will afford new insights into the intracellular pathways that mediate hypoxic signaling. PUBLIC HEALTH RELEVANCE: This project is highly relevant to public health because the goals are to discover and develop new drugs to treat breast, prostate, and other forms of cancer. The proposed research is aimed at the discovery of tumor-selective small molecules that will have markedly fewer side effects and less toxicity than most current chemotherapeutic agents. These compounds will target unique physiological differences in the tumor environment and specific genetic differences in tumor cells that allow them to survive and grow even under conditions where they are deprived of oxygen.