Identification of esculin as a direct modulator of IGF1 in cervical cancer with integrated computational and experimental studies

Aberrant activation of the insulin-like growth factor 1 (IGF1) signaling axis plays a central role in tumor proliferation, metastasis, and therapeutic resistance. Although most therapeutic strategies have focused on inhibition of the IGF1 receptor (IGF1R), direct targeting of the IGF1 ligand remains largely underexplored. An integrated computational-experimental pipeline was employed to identify phytochemicals that directly modulate IGF1. In the computational phase, a library of 75 natural compounds was screened by molecular docking against model 11 of the NMR conformer of IGF1 (PDB ID: 1PMX), followed by ADMET profiling, PASS-based biological activity prediction, and 500-ns all-atom molecular dynamics (MD) simulations complemented by essential dynamics, free-energy landscape (FEL), and MM-PBSA analyses. In the experimental phase, the top candidates were evaluated using in vitro cytotoxicity assays, ELISA-based IGF1 quantification, and fluorescence spectroscopy with Stern–Volmer analysis. Esculin and rotenone were identified as the top-ranked binders from docking analyses. ADMET profiling indicated more favorable pharmacokinetic and safety characteristics for esculin. PASS predictions supported anticancer and antimetastatic potential for both compounds. Long-timescale MD simulations indicated that esculin altered IGF1 conformational dynamics, as reflected by reduced backbone deviation, controlled residue flexibility, persistent hydrogen-bonding interactions, and confinement within a distinct thermodynamically favorable energy basin compared with apo IGF1 and the rotenone-bound complex; MM-PBSA re-scoring returned comparable total binding free energies for the two complexes. In vitro assays subsequently demonstrated a clear dose-dependent cytotoxic effect of esculin in HeLa cells, whereas rotenone showed minimal antiproliferative effects. Esculin significantly reduced intracellular IGF1 protein levels (p < 0.001) and directly interacted with recombinant IGF1, as indicated by fluorescence quenching. Esculin is identified as a promising natural IGF1-binding compound with modulatory potential, supported by consistent computational and experimental evidence. These findings highlight its potential as a lead compound for the development of IGF1-targeted anticancer therapies.