This study aimed at developing metformin hydrochloride (Met) encapsulated liposomal vesicles for enhanced therapeutic outcomes at reduced doses against breast cancer. Liposomal Met was prepared using thin-film hydration through various loading methods; passive loading, active loading, and drug-loaded lipid film. The drug-loaded film method exhibited maximum entrapment efficiency (~65%) as compared to active loading (~25%) and passive loading (~5%) prepared Met-loaded liposomes. The therapeutic efficacy of these optimized liposomes was evaluated for cellular uptake, cytotoxicity, inhibition of metastatic activity, and apoptosis-inducing activity. Results demonstrated significantly superior activity of positively charged liposomes resulting in reduced IC50 values, minimal cell migration activity, reduced colony formation, and profound apoptosis-induced activity in breast cancer cells as compared to Met. The anti-tumor activity was investigated using a clinically relevant in vitro tumor simulation model, which confirmed enhanced anti-tumorigenic property of liposomal Met over Met itself. To the authors' knowledge, this is the first report of Met-loaded liposomes for improving the efficacy and therapeutic effect of Met against breast cancer. With the results obtained, it can be speculated that liposomal encapsulation of metformin offers a potentially promising and convenient approach for enhanced efficacy and bioavailability in breast cancer treatment.
Keywords: 3D spheroids; AMPK activation; breast cancer; liposomes; metformin.