Targeting the G-quadruplex structure in the hTERT promoter for telomerase activity: in silico screening of phyto-compounds and long timescale replica exchange molecular dynamic simulations

Telomerase activity plays a crucial role in maintaining telomere length and cellular immortality, making it an attractive target for cancer therapy. The human telomerase reverse transcriptase (hTERT) promoter contains a G-rich region that can form G-quadruplex (G4) structures, which regulate hTERT expression. In this study, we used in silico screening and molecular dynamics simulations to identify phyto-compounds that can stabilise the G4 structure in the hTERT promoter. We performed shape-based and pharmacophore-based screening of a phytochemical database and identified two hit compounds with assistance from oleanolic acid and maslinic acid as controls, which showed in vitro telomerase activity. Molecular docking and replica exchange molecular dynamic simulations for 2000 nanoseconds for a temperature profile of 310 to 350 K were used to evaluate the binding affinity and stability of these compounds with two different G4 conformations in the hTERT promoter. Our results suggest that astragaloside-1 can stabilise the parallel-stranded G4 conformation (2 kze) in the hTERT promoter, while novel compounds may be required to stabilise the intramolecular G4 conformation (2 kzd). Our study highlights the potential of in silico screening and molecular dynamic simulations in identifying hit compounds for targeting G4 structures.