Rutin Potentially Binds the Gamma Secretase Catalytic Site, Down Regulates the Notch Signaling Pathway and Reduces Sphere Formation in Colonospheres

Rutin, a natural flavonol, can modulate molecular signaling pathways and has considerable potential in cancer treatment. However, little is known about the effect of rutin on the notch signaling pathway (NSP) in cancer and cancer stem-like cells. In this study, we explored the effect of rutin on gamma secretase (GS, a putative notch signaling target) inhibition mediated NICD (Notch Intracellular Domain) production in colon cancer cells. Molecular docking, MM-GBSA, and Molecular dynamics (MD) simulation experiments were performed to check rutin’s GS catalytic site binding potential. The HCT-116 colon cancer and cancer stem-like cells (colonospheres) were utilized to validate the in silico findings. The NICD production, notch promoter assay, expression of notch target genes, and cancer stemness/self-renewal markers were studied at molecular levels. The results were compared with the Notch-1 siRNA transfected test cells. The in silico study revealed GS catalytic site binding potential in rutin. The in vitro results showed a decreased NICD formation, an altered notch target gene (E-cad, Hes-1, and Hey-1) expression, and a reduction in stemness/self-renewal markers (CD44, c-Myc, Nanog, and Sox2) in test cells in a time and dose-dependent manner. In conclusion, rutin inhibits the notch signaling pathway and reduces the stemness/self-renewal property in colon cancer cells and the colonospheres by targeting gamma secretase. The clinical efficacy of rutin in combination therapy in colon cancer may be studied in the future.