Cancer-Related Glycolytic Gene:Regulation and Targeting

描述(申请人提供)：本申请侧重于编码II型己糖激酶的基因的调节和靶向，该基因是许多癌症的生长和发病机制中的主要参与者。这种酶对于保持癌症最常见的生化特征，即它们以高速率代谢葡萄糖的能力是必不可少的。表达这种表型的癌症通常是最恶性的，生长迅速，经常发生转移。在这类细胞中过表达的II型己糖激酶即使在低氧条件下也能促进它们的快速生长和存活。值得注意的是，在过去的进展期间，我们提供了证据表明，表观遗传因素，即去甲基化和甲基化可能对于分别开启和关闭II型己糖激酶基因是重要的；低氧条件+葡萄糖提供了最大的激活；启动子的大部分强度位于转录起始点附近；以及反义己糖激酶RNA可以显著抑制培养的肿瘤细胞的生长。最后，使用肝癌的动物模型，我们在一项测试研究中表明，烷化剂3-溴丙酮酸可以通过直接靶向(通过动脉注射)II型己糖激酶和线粒体ATP合成来阻止肿瘤的生长。这项工作为该项目未来的三个具体目标提供了坚实的基础：1.阐明与转化相关的表观遗传学事件的分子基础，这些事件完全使包含转录起始点的CpG岛去甲基化并打开II型己糖激酶基因。2.鉴定II型己糖激酶基因CpG岛上的低氧敏感元件(S)，评价低氧胁迫对II型己糖激酶基因甲基化模式和表达的影响。3.评价靶向II型己糖激酶的RNA和化学制剂在肝癌/肺转移兔模型中的相对治疗效果。考虑到目前在世界范围内普遍用于检测癌症和监测其治疗的FDG-PET主要基于己糖激酶的高表达水平，似乎这种酶可能显著促进人类患者的许多癌症。有鉴于此，这里提出的基础工作，既专注于识别沉默和促进II型己糖激酶的潜在机制，又专注于识别抑制它的新药物，可能有助于扭转我们在抗癌战争中失利的局面。

DESCRIPTION (provided by applicant): This application focuses on the regulation and targeting of the gene that encodes Type II hexokinase, a major player in the growth and pathogenesis of many cancers. This enzyme is essential for maintaining the most common biochemical signature of cancers, i.e., their capacity to metabolize glucose at high rates. Cancers expressing this phenotype are usually the most malignant, growing rapidly and frequently becoming metastatic. The overexpressed Type II hexokinase in such cells promotes their rapid growth and survival even under hypoxic conditions. Significantly, during the past progress period we provided evidence that epigenetic factors, i.e., demethylation and methylation may be important for respectively turning the Type II hexokinase gene on and off; that hypoxic conditions + glucose provide maximal activation; that much of the strength of the promoter lies in the region encompassing the transcription start site; and that antisense hexokinase RNA can inhibit markedly tumor cell growth in culture. Finally, using an animal model for liver cancer, we showed in a test study that the alkylating agent 3-bromopyruvic acid can arrest tumor growth by targeting directly (via intraarterial injection) both Type II hexokinase and mitochondrial ATP synthesis. This work has provided a strong foundation for the future Specific Aims of this project that are threefold: 1. Elucidate the molecular basis of those transformation-related epigenetic events that completely demethylate the CpG island encompassing the transcription start site and "switch on" the Type II hexokinase gene. 2. Identify the hypoxia sensitive element(s) within the CpG island of the Type II hexokinase gene and evaluate the effect of hypoxic stress both on the methylation pattern and on the expression of Type II hexokinase. 3. Assess the relative therapeutic efficacies of RNA and chemical based agents targeted to Type II hexokinase in a liver cancer/lung metastasis rabbit model. Considering that FDG-PET, now commonly used worldwide to detect cancer and monitor its treatment, is based largely on elevated expression levels of hexokinase, it would seem that numerous cancers in human patients may be markedly promoted by this enzyme. In this light, the basic work proposed here that focuses both on identifying the underlying mechanisms that silence and promote Type II hexokinase and in identifying novel agents that inhibit it, may help turn the tide on our losing war on cancer.