Birts Charles N, Nijjar Sharandip K, Mardle Charlotte A, Hoakwie Franciane, Duriez Patrick J, Blaydes Jeremy P, Tavassoli Ali
Chemistry, University of Southampton, Southampton, SO17 1BJ, UK.
Cancer Sciences, Faculty of Medicine, University of Southampton, Southampton, SO16 6YD, UK.
Chem Sci. 2013 Aug 1;4(8):3046-3057. doi: 10.1039/c3sc50481f.
Identification of direct modulators of transcription factor protein-protein interactions is a key challenge for ligand discovery that promises to significantly advance current approaches to cancer therapy. Here, we report an inhibitor of NADH-dependent dimerization of the C-terminal binding protein (CtBP) transcriptional repressor, identified by screening genetically encoded cyclic peptide libraries of up to 64 million members. CtBP dimers form the core of transcription complexes associated with epigenetic regulation of multiple genes that control many characteristics of cancer cells, including proliferation, survival and migration. CtBP monomers also have distinct and critical cellular function, thus current experimental tools that deplete all forms of a targeted protein ( siRNA) do not allow the cellular consequences of this metabolically regulated transcription factor to be deciphered. The most potent inhibitor from our screen (-SGWTVVRMY) is demonstrated to disrupt CtBP dimerization and in cells. This compound is used as a chemical tool to establish that the NADH-dependent dimerization of CtBPs regulates the maintenance of mitotic fidelity in cancer cells. Treatment of highly glycolytic breast cancer cell lines with the identified inhibitor significantly reduced their mitotic fidelity, proliferation and colony forming potential, whereas the compound does not affect mitotic fidelity of cells with lower glycolytic flux. This work not only links the altered metabolic state of transformed cells to a key determinant of the tumor cell phenotype, but the uncovered compound also serves as the starting point for the development of potential therapeutic agents that target tumors by disrupting the CtBP chromatin-modifying complex.
鉴定转录因子蛋白-蛋白相互作用的直接调节剂是配体发现面临的一项关键挑战，有望显著推进当前的癌症治疗方法。在此，我们报告了一种C端结合蛋白（CtBP）转录抑制因子的NADH依赖性二聚化抑制剂，它是通过筛选多达6400万个成员的基因编码环肽文库鉴定出来的。CtBP二聚体构成了与多个基因的表观遗传调控相关的转录复合物的核心，这些基因控制着癌细胞的许多特性，包括增殖、存活和迁移。CtBP单体也具有独特且关键的细胞功能，因此目前耗尽所有形式靶向蛋白的实验工具（小干扰RNA）无法解读这种代谢调控转录因子的细胞后果。我们筛选出的最有效抑制剂（-SGWTVVRMY）在体外和细胞中均能破坏CtBP二聚化。该化合物被用作化学工具，以证实CtBP的NADH依赖性二聚化调节癌细胞有丝分裂保真度的维持。用所鉴定的抑制剂处理高度糖酵解的乳腺癌细胞系，可显著降低其有丝分裂保真度、增殖和集落形成潜力，而该化合物不影响糖酵解通量较低的细胞的有丝分裂保真度。这项工作不仅将转化细胞改变的代谢状态与肿瘤细胞表型的关键决定因素联系起来，而且所发现的化合物还可作为开发潜在治疗药物的起点，这些药物通过破坏CtBP染色质修饰复合物来靶向肿瘤。
