Inhibiting Multi-Functional ALDOA for Cancer Therapy

果糖-二磷酸缩醛酶A(ALDOA)是一种古老的、高表达的基因，它已经获得了三种 不同的细胞活动。最被理解的活性是催化有氧糖酵解的关键步骤。ALDOA 也具有与其催化活性(“兼职”)无关的蛋白质结合活性，包括结合到 细胞骨架蛋白，它使用一个“EΦE”基序，可以放入奥尔多的“兼职口袋”中。绑定到 细胞骨架肌动蛋白使Aldo处于不活跃的状态，直到需要它时，它会通过增加 其底物果糖-1，6-二磷酸和/或生长因子诱导的PI-3-激酶活性水平。另一个 ALDOA的兼职功能是它存在于癌细胞的细胞核中，在那里它与 增加了扩散。一种可能性是核ALDOA与核内EID-1上的EΦE基序结合 抑制HIF-1‘S转录共激活因子p300。ALDOA水平在许多癌症中都会升高，尤其是 胰腺癌，在那里，它已经被认为与患者生存不良和转移增加有关。胰腺 癌细胞有高水平的厌氧糖酵解，这种糖酵解在低氧诱导下进一步增加。 转录因子1(HIF-1)。HIF-1诱导ALDOA和其他糖酵解酶，进而维持高水平 HIF-1活性通过依赖AMPK/p300的前馈循环。HIF-1活性导致血管内皮生长因子释放和 血管生成，以及其他癌细胞存活机制的诱导。糖酵解增加提供了 能量(ATP)和生物量必需代谢物供应增加的低氧癌细胞 综合。ALDOA升高还与E-钙粘附素降低有关，E-钙粘附素是癌细胞紧密连接的组成部分 (TJ)细胞间相互作用所必需的，提供更多的间充质表型和增加肿瘤 转移。这很可能是由于ALDOA与细胞骨架肌动蛋白的EΦE基序结合导致其 聚合和解体，或失去E-钙粘附素的TJ的其他失活。所有这一切使ALDOA 一个特殊的可用药抗癌靶点。我们的X射线结晶学研究已经确定了一个新的角色 Aldo的C-末端结构域的催化活性，以及活性Cys289残基 催化活性的变构调节。我们已经确定了一种新的ALDOA的铅探针变构抑制剂 与Cys289形成抑制糖酵解、HIF-1活性和癌细胞增殖的复合体，以及 体内抑制糖酵解和肿瘤异种移植模型中的肿瘤生长。使用这种生物稳定的变构 作为先导，我们的目标之一是制造更有效的抑制剂，与变构位点Cys289结合，AS 以及同时结合活性部位和兼职口袋的高亲和力双功能抑制剂。 我们将使用X射线结晶学来帮助我们设计调节HIF-1活性的核调节因子的抑制剂； 尤其是设计ALDOA催化活性的直接抑制剂。我们将使用这些化合物作为 抑制ALDOA各种活性的药理探针，并作为新的治疗方法的潜在线索 胰腺癌和其他癌症的治疗。

Fructose-bisphosphate aldolase A (ALDOA) is an ancient, highly expressed gene that has acquired three distinct cellular activities. The best understood activity is catalyzing a key step in aerobic glycolysis. ALDOA also has protein binding activities independent of its catalytic activity (“moonlighting”), that include binding to cytoskeletal proteins, which use an “EΦE” motif that fits into a “moonlighting pocket” of ALDO. Binding to the cytoskeleton actin holds ALDO in an inactive form until it is needed, when it is released by an increase in the levels of its substrate fructose-1, 6-bisphosphate and/or by growth-factor-induced PI-3-kinase activity. Another moonlighting function of ALDOA is its presence in the nucleus of cancer cells, where it is associated with increased proliferation. One possibility is that nuclear ALDOA binds to the EΦE motif on EID-1 in the nucleus to inhibit HIF-1's transcriptional co-activator, p300. ALDOA levels are increased in many cancers, particularly pancreatic cancer, where it has been linked to poor patient survival and an increase in metastasis. Pancreatic cancer cell has high levels of anaerobic glycolysis that is further increased by the hypoxia inducible transcription factor-1 (HIF-1). HIF-1 induces ALDOA and other glycolytic enzymes that in turn maintain high HIF-1 activity through an AMPK/p300-dependent feed-forward loop. HIF-1 activity leads to VEGF release and angiogenesis, and the induction of other cancer cell survival mechanisms. Increased glycolysis provides hypoxic cancer cells with an increased supply of energy (ATP) and essential metabolites for biomass synthesis. Elevated ALDOA is also associated with low E-cadherin, a component of cancer cell tight junctions (TJ) necessary for cell-cell interactions, giving a more mesenchymal phenotype and increased tumor metastasis. This most likely is due to binding of ALDOA to the EΦE motif of cytoskeleton actin causing its polymerization and disassembly, or other inactivation of the TJ with loss of E-cadherin. All this makes ALDOA an exceptional druggable anti-cancer target. Our X-ray crystallography studies have identified a new role for the C-terminal domain of ALDO in its catalytic activity, as well as a reactive Cys289 residue that allows allosteric regulation of catalytic activity. We have identified a novel lead probe allosteric inhibitor of ALDOA that forms a complex with Cys289 inhibiting glycolysis, HIF-1 activity and the proliferation of cancer cells, and in vivo inhibits glycolysis and tumor growth in a tumor xenograft model. Using this biologically stable allosteric inhibitor as a lead, one of our goals is to make more potent inhibitors that bind to the allosteric site Cys289, as well as high affinity bifunctional inhibitors that simultaneously engage the active site and moonlighting pocket. We will use X-ray crystallography to help us design inhibitors that modulate nuclear regulators of HIF-1 activity; and not least to design direct inhibitors of ALDOA catalytic activity. We will use these compounds as pharmacological probes to inhibit the various activities of ALDOA, and as potential leads for new therapies for the treatment of pancreatic, and other cancers.