Substrate Specificity Determinants in Cancer-related Solute Carrier Transporters

描述（由申请人提供）：细胞代谢的改变支持细胞的快速生长和增殖-癌症的关键标志。溶质载体（SLC）转运蛋白是介导溶质如代谢物和药物跨膜运动的膜蛋白，也可以在癌症代谢途径中协同起作用。例如，氨基酸转运体lat1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，这些氨基酸被用作营养物质来构建生物量和信号分子以促进增殖。我们的总体目标是通过综合实验和计算方法描述选定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，通过实验验证（由合作者执行），确定新的配体，包括三种与癌症相关的SLC转运体（即GLUT1、ASCT2和lat1）的内源性代谢物和处方药。本研究的结果将揭示转运蛋白的未知功能，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预测的转运体-配体复合物的分析来定义结构相关转运体的底物特异性规则。特异性决定因素将用于合理化和预测遗传变异对转运蛋白功能的影响。第三，制定合理设计的方法

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.