Rational design of novel procaspase-3 activators for the targeted therapy of triple-negative breast cancer.

Triple-negative breast cancer (TNBC) remains a formidable clinical challenge owing to its aggressive phenotype and limited treatment options. To address this, we employed ligand-based rational drug design coupled with scaffold hybridization to develop a series of novel procaspase-3 activators. From 28 designed compounds, F17 and F21 emerged as lead candidates, exhibiting superior in vitro procaspase-3 activation. Density functional theory calculations confirmed their enhanced zinc-binding affinity, with adsorption energies (Eads) of -14.8332 eV (F17) and -14.8797 eV (F21), compared to -12.7474 eV for PAC-1, along with stronger electrostatic potential minima (-67.20 and -66.99 kcal/mol, respectively). In silico ADMET profiling indicated favorable drug-like properties, including good aqueous solubility, low blood-brain barrier penetration, and moderate intestinal absorption. In TNBC MDA-MB-231 models, both compounds demonstrated potent anti-proliferative activity, with IC values of 25.82 μM (F17) and 25.03 μM (F21) after 48 h, outperforming PAC-1 (33.81 μM). They also significantly inhibited cell migration, reducing wound closure to 11.19% (F21) compared with 20.60% in controls, and induced caspase-3-dependent apoptosis. Importantly, in vivo neurotoxicity assessments revealed no significant neuronal damage at doses up to 50 mg/kg, underscoring their improved safety profile over earlier activators. These results establish F21 as a particularly promising preclinical candidate and provide a rational framework for developing target-specific, neurotoxicity-sparing procaspase-3 activators for TNBC therapy.