Miglietta Giulia, Cogoi Susanna, Marinello Jessica, Capranico Giovanni, Tikhomirov Alexander S, Shchekotikhin Andrey, Xodo Luigi E
Department of Medicine, Biochemistry Laboratory, University of Udine , 33100 Udine, Italy.
Department of Pharmacy and Biotechnology, University of Bologna , 40100 Bologna, Italy.
J Med Chem. 2017 Dec 14;60(23):9448-9461. doi: 10.1021/acs.jmedchem.7b00622. Epub 2017 Dec 1.
The human KRAS transcript contains a G-rich 5'-UTR sequence (77% GC) harboring several G4 motifs capable to form stable RNA G-quadruplex (RG4) structures that can serve as targets for small molecules. A biotin-streptavidin pull-down assay showed that 4,11-bis(2-aminoethylamino)anthra[2,3-b]furan-5,10-dione (2a) binds to RG4s in the KRAS transcript under low-abundance cellular conditions. Dual-luciferase assays demonstrated that 2a and its analogue 4,11-bis(2-aminoethylamino)anthra[2,3-b]thiophene-5,10-dione (2b) repress translation in a dose-dependent manner. The effect of the G4-ligands on Panc-1 cancer cells has also been examined. Both 2a and 2b efficiently penetrate the cells, suppressing protein p21KRAS to <10% of the control. The KRAS down-regulation induces apoptosis together with a dramatic reduction of cell growth and colony formation. In summary, we report a strategy to suppress the KRAS oncogene in pancreatic cancer cells by means of small molecules binding to RG4s in the 5'-UTR of mRNA.
人类KRAS转录本包含一个富含G的5'-UTR序列（GC含量为77%），其中含有几个能够形成稳定RNA G-四链体（RG4）结构的G4基序，这些结构可作为小分子的作用靶点。生物素-链霉亲和素下拉实验表明，在低丰度细胞条件下，4,11-双（2-氨基乙氨基）蒽[2,3-b]呋喃-5,10-二酮（2a）与KRAS转录本中的RG4结合。双荧光素酶实验证明，2a及其类似物4,11-双（2-氨基乙氨基）蒽[2,3-b]噻吩-5,10-二酮（2b）以剂量依赖的方式抑制翻译。还检测了G4配体对Panc-1癌细胞的作用。2a和2b均能有效穿透细胞，将蛋白p21KRAS抑制至对照的<10%。KRAS的下调诱导细胞凋亡，同时细胞生长和集落形成显著减少。总之，我们报道了一种通过小分子与mRNA 5'-UTR中的RG4结合来抑制胰腺癌细胞中KRAS癌基因的策略。
