Molecular Mechanisms of Regulation and Modulation of Sphingosine Kinase 1 Activity in Cancer

 描述(由申请人提供)：这项提案的中心目标是了解鞘氨醇激酶1(SK1)是如何被调节的，以便建立更好的抑制剂作为替代癌症治疗方法。SK1是鞘磷脂代谢途径中的一个重要酶，因为它位于促细胞凋亡的鞘磷脂神经酰胺和鞘氨醇和促生存和促血管生成的脂鞘氨醇-1-磷酸(S1P)之间。S1P已被证明具有细胞内和细胞间的信号特性，在血管生成和侵袭中发挥重要作用。SK1已经在许多不同的癌症类型和细胞系中被检测到。此外，SK1活性已被证明在几种不同的癌症类型中过度表达。以往的研究表明，SK1的活性受阴离子磷脂(APL)的调节，APL存在于所有细胞的质膜中。此外，还表明SK1可以转运到其底物所在的质膜上。尽管SK1和S1P在癌症中的作用得到了强有力的潜在支持，但对控制SK1激活并最终控制S1P水平的分子机制缺乏了解。基于这些前提，我们在特定的目标1中寻求确定APL在体外、细胞内和结构生物学中激活SK1的分子机制，我们认为这是通过一个新的APL结合位点来介导的。此外，我们还将观察SK1膜结合突变体对S1P介导的癌症生物学反应的影响，包括迁移和侵袭相关蛋白Ezrin的磷酸化。此外，我还发现了SK1和磷脂酰肌醇磷酸(PIP)之间的新的相互作用，这种作用也可以在质膜上发现。我已经证明，即使在激活的APL存在的情况下，某些PIP也可以去激活SK1。在具体目标2中，这项建议旨在了解这些相互作用及其对癌细胞侵袭和血管生成的生物学影响。目前，还没有美国食品和药物管理局批准的SK1抑制剂用于治疗任何疾病。因此，有必要开发SK1抑制剂作为癌症的替代治疗选择。这些研究的首要目标是了解APL激活SK1的分子机制以及PIP如何影响SK1的活性。了解SK1活性被变构调节的机制将打开一类新的SK1抑制剂的大门，这些抑制剂靶向SK1与膜结合的能力，从而限制其对底物的访问。针对S1P的生产为抗癌治疗开辟了一条新的途径。

 DESCRIPTION (provided by applicant): The central goal of this proposal is to understand how sphingosine kinase 1 (SK1) is regulated in order to build better inhibitors as alternative cancer therapeutics. SK1 is an important enzyme in the sphingolipid metabolism pathway as it sits between the pro-apoptotic sphingolipids ceramide and sphingosine and the pro- survival and pro-angiogenic lipid sphingosine-1-phosphate (S1P). S1P has been shown to have both intra- and inter-cellular signaling properties that play an important role in angiogenesis and invasion. SK1 has been detected in numerous different cancer types and cell lines. Additionally, SK1 activity has been shown to be over-expressed in several different cancer types. SK1 activity has been previously shown to be modulated by anionic phospholipids (APLs) which can be found in the plasma membrane of all cells. Furthermore, it has been shown that SK1 can translocate to the plasma membrane where its substrate is located. Despite the strong underlying support for the roles of SK1 and S1P in cancer, there is a lack in understanding of the molecular mechanisms that control SK1 activation and ultimately S1P levels. Based on these premises, we seek in Specific Aim 1 to determine the molecular mechanism of SK1 activation by APLs, both in vitro, in cells, and through structural biology, which we suggest is mediated through a novel APL binding site. Additionally, we will look at the effects of the SK1 membrane binding mutants on S1P-mediated cancer biological responses including phosphorylation of the migration and invasion associated protein Ezrin. Furthermore, I have identified novel interactions between SK1 and phosphatidylinositol phosphates (PIPs) which can also be found at the plasma membrane. I have shown that certain PIPs can de-activate SK1 even in the presence of activating APLs. This proposal, in specific Aim 2, aims at understanding these interaction and their biological consequences to cancer cell invasion and angiogenesis. Currently, there are no inhibitors of SK1 approved by the U.S. Food and Drug Administration for the treatment of any disease. Therefore, there is a need for the development of SK1 inhibitors as alternative therapeutic options for cancer. The overarching goal of these studies is to understand the molecular mechanism of SK1 activation by APLs and how PIPs can affect SK1 activity. Understanding the mechanisms by which SK1 activity is allosterically modulated will open the door to a new class of SK1 inhibitors which target SK1s ability to bind to the membrane, therefore limiting its access to its substrate. Targeting S1P production allows for a new avenue of anti-cancer therapies.