Microtubule-targeting and regulation of HIF-1

说明(申请人提供)：2-甲氧基雌二醇(2ME2)是雌二醇的一种天然衍生物，目前正处于L/11期临床试验中，作为肿瘤血管生成的抑制剂。我们最近报道，2ME2有效地抑制促血管生成和促生存转录因子HIF-1α的蛋白水平和转录活性。此外，我们还发现，HIF-1α抑制发生在2ME2破坏微管细胞骨架的下游。这些数据提供了靶向微管细胞骨架和抑制肿瘤血管生成之间的第一个机制联系。然而，导致微管破坏导致HIF-1α抑制的细胞信号仍然未知。通过这一建议，我们试图在我们以前工作的基础上，详细研究从微管破坏到抑制肿瘤血管生成和生存的分子机制(S)。我们的假设是，2ME2在微管依赖的HIF-1α激活的化学力学中具有二价效应。2ME2通过破坏细胞微管，抑制HIF-1α的核转位和翻译，从而抑制HIF-1α的活性。为了阐明微管破坏调节HIF-1α活性的机制，我们计划：1)阐明2ME2抑制HIF-1核转位的机制；2)确定2ME2抑制HIF-1α翻译的机制；3)研究在VHL突变的肾细胞癌中，取消对HIF-1α的微管依赖调节是否导致2ME2耐药。我们还将把这些观察扩大到其他类别的微管靶向药物，如紫杉烷、埃博西酮和长春花碱。通过这项建议，我们试图在以前工作的基础上，促进我们对HIF途径微管依赖调节的基本机制的理解，以及它们对肿瘤生存和化疗敏感性的影响。

DESCRIPTION (provided by applicant): 2-Methoxyestradiol (2ME2) is a naturally occurring derivative of estradiol currently in Phase l/ll clinical trials as an inhibitor of tumor angiogenesis. We have recently reported that 2ME2 potently inhibits the protein levels and transcriptional activity of the pro-angiogenic and pro-survival transcription factor HIF-1 alpha. Moreover, we showed that HIF-1 alpha inhibition occurs downstream of disruption of the microtubule cytoskeleton by 2ME2. These data provide the first mechanistic link between targeting of the microtubule cytoskeleton and inhibition of tumor angiogenesis. However, the cellular signals that lead from microtubule disruption to HIF-1 alpha inhibition remain unknown. With this proposal, we seek to build upon our previous work in order to investigate in detail the molecular mechanism(s) that lead from microtubule disruption to inhibition of tumor angiogenesis and survival. Our hypothesis is that 2ME2 has a bivalent effect on the chemomechanics of microtubule-dependent HIF-1 alpha activation. By disrupting cellular microtubules, 2ME2 inhibits HIF-1 alpha nuclear translocation and HIF-1 alpha translation, thus, resulting in inhibition of HIF-1 alpha activity. To elucidate the mechanism by which microtubule disruption regulates HIF-1 alpha activity we plan to: I) Elucidate the mechanism by which 2ME2 inhibits HIF-1 nuclear translocation, II) Define the mechanism by which 2ME2 inhibits HIF-1 alpha translation and III) Investigate whether abrogation of microtubule-dependent regulation of HIF-1 alpha in VHL-mutant renal cell carcinomas (RCCs), results in 2ME2 resistance. We will also expand these observations to additional classes of microtubule-targeting drugs, such as the taxanes, the epothilones and the vinca alkaloids. With this proposal we are seeking to build on our previous work and advance our understanding of the basic mechanisms governing the microtubule-dependent regulation of the HIF pathway, as well as their impact on tumor survival and chemosensitivity.