Substrate Specificity Determinants in Cancer-related Solute Carrier Transporters

描述(申请人提供)：细胞新陈代谢的改变支持细胞的快速生长和增殖--癌症的关键特征。溶质载体(SLC)转运蛋白是一种膜蛋白，它可以调节代谢产物和药物等溶质的跨膜运动，也可以在肿瘤代谢途径中发挥协同作用。例如，氨基酸转运蛋白LAT-1和ASCT2在胶质瘤中高度上调，它们在为生长中的肿瘤细胞提供必需氨基酸方面发挥关键作用，这些氨基酸被用作构建生物量的营养物质和促进增殖的信号分子。我们的广泛目标是通过综合实验和计算方法，描述选定的癌症相关转运蛋白家族中的底物特异性决定因素，从而了解癌症的机制。首先，我们将使用比较建模、虚拟筛选和化学信息学方法确定新的配体，包括三种癌症相关SLC转运体(即GLUT1、ASCT2和LAT-1)的内源性代谢物和处方药，然后进行实验验证(由合作者执行)。在这一目标中获得的结果将揭示转运蛋白未知的功能，并为进一步表征其功能提供新的化学工具。其次，我们将使用结构比较方法和对预测的转运体-配体复合体的分析，定义结构相关转运体的底物专一性规则。特异性决定因素将被用来合理化和预测遗传变异对转运蛋白功能的影响。第三，开发合理设计的方法 为癌症代谢途径中的转运蛋白提供多药物配体，并检测已发现的配体对多形性胶质母细胞瘤(GBM)细胞系的抗增殖作用。我们将进一步确定转运蛋白及其配体在癌症中的作用，通过化学相似方法预测以前未知的蛋白质-小分子相互作用。最后，基于我们的结果，我们将对正常细胞和转化细胞代谢途径之间的差异和共性进行合理化。表征关键的膜转运体和它们的小分子配体之间的相互作用将有助于我们理解溶质是如何通过细胞膜和细胞器运输的，这是许多生命过程中必不可少的。此外，描述对癌症代谢重要的蛋白质的底物特异性将提供化学工具，使我们能够了解扰动的代谢网络如何与癌症相关，并发现新的线索，以设计具有优化亲和力的小分子来对抗新的抗癌药物靶点。最终，我们研究中获得的结果可能是朝着设计抗癌药物迈出的重要一步。

DESCRIPTION (provided by applicant): Alterations in cell metabolism support rapid growth and proliferation of cells - key hallmarks of cancer. Solute Carrier (SLC) transporters are membrane proteins that mediate the movement of solutes such as metabolites and drugs across membranes, and can also function cooperatively in cancer metabolism pathways. For exam- ple, the amino acid transporters LAT-1 and ASCT2 are highly upregulated in glioma, where they play a key role in supplying growing tumor cells with essential amino acids that are used as nutrients to build biomass and signaling molecules to enhance proliferation. Our broad goal is to understand cancer mechanisms, by de- scribing the substrate specificity determinants in selected cancer-related transporter families via an integrated experimental and computational approach. First, we will identify novel ligands including endogenous metabolites and prescription drugs for three cancer- related SLC transporters (i.e., GLUT1, ASCT2, and LAT-1), using comparative modeling, virtual screening, and chemoinformatics methods, followed by experimental validation (performed by collaborators). The results obtained in this Aim will reveal unknown functions of the transporters and provide novel chemical tools to further characterize their functions. Second, we will define rules for substrate specificity of structurally related transporters, using structural comparison methods and analysis of the predicted transporter-ligand complexes. The specificity determinants will be used to rationalize and predict the impact of genetic variation on trans- porter function. Third, we will develop methods to rationally design polypharmacological ligands for transporters in cancer-metabolism pathways and examine the anti-proliferative effect of the discovered ligands on glioblastoma multiforme (GBM) cell lines. We will further establish the role of the transporters and their ligands in cancer, by predicting previously unknown protein-small molecule interactions via chemical similarity methods. Finally, based on our results, we will rationalize differences and commonalities between metabolic pathways of normal and transformed cells. Characterizing the interactions between key membrane transporters and their small molecule ligands will con- tribute to our understanding of how solutes get transported across the membranes of cells and organelles, which is essential for many of life's processes. Furthermore, describing substrate specificity in proteins important for cancer metabolism will provide chemical tools that would allow us to understand how perturbed metabolic networks are related to cancer and to discover novel leads for designing small molecules with optimized affinities against novel cancer drug targets. Ultimately, the results obtained in our studies can be a significant step toward designing cancer drugs.