Hesperidin potentially interacts with the catalytic site of gamma-secretase and modifies notch sensitive genes and cancer stemness marker expression in colon cancer cells and colonosphere.

Gamma secretase (GS) produces Notch Intracellular Domain (NICD) by trans-membrane cleavage of notch receptor. The NICD enters the nucleus and activates the notch signaling pathway (NSP) by activating notch-responsive gene transcription. Hyperactivation of NSP is related to cancer aggressiveness, therapy resistance, and poor therapy outcome, and decreased overall disease-free survival in patients. Till date, none of the GS inhibitors (GSI) has been clinically approved due to their toxicity in patients. Thus in the present study, we explored the GS catalytic site binding potential of hesperidin (natural flavone glycoside) and its effect on notch responsive gene expression in HCT-116 cells. Molecular docking, MM-GBSA binding energy calculations, and molecular dynamics (MD) simulation experiments were performed to study the GS catalytic site binding potential of hesperidin. The compound showed better GS catalytic site binding potential at the active site compared to experimentally validated GSI, N-N-(3, 5-Difluorophenacetyl)-L-alanyl-S-phenylglycine t-butyl ester (DAPT) in molecular docking and MM-GBSA experiments. MD simulation results showed that hesperidin forms stable and energetically favorable complex with gamma secretase in comparison to standard inhibitor (DAPT)-GS complex. Further, experiments showed that hesperidin inhibited cell growth and sphere formation potential in HCT-116 cells. Further, hesperidin treatment altered notch responsive genes (Hes1, Hey1, and E-cad) and cancer stemness/self-renewal markers expression at transcription levels. In conclusion, hesperidin produces toxicity in HCT-116 cells and decreases colonosphere formation by inhibiting transcription of notch signaling pathway target genes and stemness markers.Communicated by Ramaswamy H. Sarma.