Evaluation of tamoxifen analogues as potential estrogen receptor alpha inhibitors for breast cancer treatment: A computational approach

Estrogen receptors, particularly ERα, play a key role in breast cancer progression, making them prime targets for therapeutic intervention. Tamoxifen (TAM), a selective estrogen receptor modulator (SERM), has been widely used for the treatment of ER+ breast cancer; however, its clinical application is limited by side effects and the emergence of resistance. This study aims to identify and evaluate TAM analogues with improved efficacy and reduced side effects by employing molecular docking and molecular dynamics (MD) simulations. Droloxifene, endoxifen, and afimoxifene emerged as promising candidates, exhibiting strong binding affinities with ERα, as indicated by highly negative binding energy (BE) values in docking simulations. MD simulations further validated the stability of the complexes formed between these analogues and ERα, with low root mean square deviation (RMSD) values and stable radius of gyration (Rg) profiles. Root mean square fluctuation (RMSF) analysis revealed balanced flexibility, with droloxifene and afimoxifene showing optimized flexibility for stable binding. Hydrogen bond analysis indicated more stable interactions between these analogues and ERα compared to TAM, suggesting enhanced binding affinity. MM/GBSA binding free energy analysis confirmed the high affinity of these analogues, with droloxifene displaying the most effective binding free energy (ΔGtotal) value. ADMET profiling suggests that droloxifene and endoxifen have superior pharmacokinetic properties relative to TAM. Overall, droloxifene, endoxifen, and afimoxifene represent promising alternatives to TAM, with the potential for further clinical development in breast cancer treatment. Experimental validation in cell-based and in vivo models will be crucial in future studies to confirm their efficacy and safety profiles. © 2024 Elsevier B.V.