Design And Activity Evaluation Of Quinoline Compounds Targeting G-quadruplexes In The Promoter Region Of C-MYC And KRAS

G-quadruplex is a special nucleic acid structure folded by guanine-rich sequence.G-quadruplex forming sequences are widely distributed in the genome of an organism.Its formation or unwinding regulates the length of telomeres and mediates the expression of certain important genes,affecting some important physiological processes in the body.It has been a novel idea for disease treatment by small molecules stabilizing intracellular G-quadruplexes and regulating the expression of related genes.Tumor is complicated disease coming from multiple gene mutations.Compounds regulating the activity of multiple tumor-related genes exhibited strong anti-tumor potential.G-quadruplex forming sequences exists in the promoter regions of multiple proto-oncogene.It is expected to mediate the activity of multiple genes by regulating the stability of the G-quadruplexes in the promoter region of proto-oncogenes,and then to control the tumor proliferation.In this work,a series of novel quinoline compounds was discovered to stabilize the G-quadruplex structures in the promoter region of proto-oncogenes c-MYC and of the KRAS.The specific process is as follows:(1)Compounds discovered by structure-based virtual screening Quinoline compounds from commercial compound libraries were discovered by virtual screening to stabilize these two G-quadruplex structures basing on the c-MYC and KRAS G-quadruplex structures.Compounds with diverse structures were found through similarity search on the base of the structures of the active compounds.After the activity assays,the structure-activity relationship analysis was carried out to determine the direction of further optimization.(2)Compound synthesis and optimization Based on the structure-activity relationship,a series of quinoline derivatives with substitution on the nitrogen-containing six-membered ring were synthesized,and the highly active compound PQ8 was found;(3)Binding mode analysis Through molecular docking,jobplot,fluorescence titration and other methods,PQ8 was proved to interact with c-MYC/KRAS G-quadruplexes through ?-? stacking;(4)Activity Evaluation on the cell level The PQ8 was found to block the the G2/M phase in MDA-MB-231 cells by cell cycle experiments;the apoptosis experiment showed that 1.5 ?M PQ8 could cause 46.77% of apoptosis;q PCR Western blot analysis showed that PQ8 could down-regulate the expression level of c-MYC/KRAS gene;(5)Evaluation for in vivo activity In a mouse model with tumors,PQ8 exhibited strong antitumor activity.Conclusion: A series of quinoline compounds were discovered and designed to stabilize the c-MYC and KRAS G-quadruplex structures in the promoter regions.PQ8 with the novel structure exhibited strong antitumor activity at the cellular level and in the mouse model.