Targeting BCL-XL-mediated apoptotic resistance in lung cancer: in silico and in vitro identification of bioactive inhibitors from Ailanthus excelsa chloroform extract.

INTRODUCTION: Lung cancer is one of the most prominent causes of cancer-related death worldwide, primarily driven by apoptosis resistance linked to the overexpression of antiapoptotic proteins. BCL-XL plays a regulatory function in cellular apoptosis, making it a critical therapeutic target in cancer treatment. In this study, we explored the potential therapeutic effects of phytocompounds isolated from leaves of Ailanthus excelsa to inhibit BCL-XL using an integrated approach combining in silico and in vitro methods.

METHODS: Phytochemical analysis of the chloroform extract of A. excelsa leaves was performed via gas chromatography-mass spectrometry (GC-MS). Compounds were selected based on their favorable pharmacokinetic properties and subjected to molecular docking against BCL-XL, followed by molecular dynamics simulations over 100 ns, analysis of the simulation trajectory RMSF, principal component analysis, and free-energy landscape. In vitro cytotoxicity of the leaf extract was assessed by MTT assay on lung cancer cell lines.

RESULTS: GC-MS identified 32 major bioactive compounds. Among these, decane,1,9-bis[(trimethylsilyl)oxy] and squalene were selected based on their favorable pharmacokinetic properties. Molecular docking studies revealed that both these compounds interact with the BH3-binding groove of BCL-XL through hydrophobic interactions. Further molecular dynamics simulations of decane,1,9-bis[(trimethylsilyl)oxy] and squalene over 100 ns confirmed the stability and compactness of the protein-ligand complex. The results of the simulation trajectory RMSF indicated stable structural conformations and minor fluctuations around the BH3 domain, suggesting effective binding. Principal component analysis and free-energy landscape exhibited that the binding of squalene promotes multiple conformational states, while decane,1,9-bis[(trimethylsilyl)oxy] limits flexibility in the protein conformations. In addition, the MTT assay conducted on lung cancer cell lines showed significant cytotoxicity of the A. excelsa leaf extract in a dose-dependent manner, highlighting its anticancer properties.

DISCUSSION: This study emphasizes the therapeutic potential of phytocompounds as natural inhibitors of BCL-XL. The integration of GC-MS profiling, molecular docking, molecular dynamics simulations, and in vitro studies provides a comprehensive strategy for the identification of plant-derived lead molecules targeting critical cancer pathways. Further in vivo investigations and molecular validations would provide better insights into BCL-XL-targeted Phyto-therapeutics for lung cancer.