Deciphering the drug delivery potential of Type1 lipid transfer protein from Citrus sinensis for enhancing the therapeutic efficacy of drugs

Type1 Non-specific Lipid Transfer Protein (CsLTP1) from Citrus sinensis is a small cationic protein possessing a long tunnel-like hydrophobic cavity. CsLTP1 performing membrane trafficking of lipids is a promising candidate for developing a potent drug delivery system. The present work includes in-silico studies and the evaluation of drugs binding to CsLTP1 using biophysical techniques along with the investigation of CsLTP1's ability to enhance the efficacy of drugs employing cell-based bioassays. The in-silico investigations identified Panobinostat, Vorinostat, Cetylpyridinium Chloride, and Fulvestrant with higher affinities and stability of binding to the hydrophobic pocket of CsLTP1. SPR studies revealed strong binding affinities of anticancer drugs, Panobinostat (KD = 1.40 μM) and Vorinostat (KD = 2.17 μM) to CsLTP1 along with the binding and release kinetics. CD and fluorescent spectroscopy revealed drug-induced conformational changes in CsLTP1. CsLTP1-associated drug forms showed remarkably enhanced efficacy in MCF-7 cells, representing increased cell cytotoxicity, intracellular ROS, reduced mitochondrial membrane potential, and up-regulation of proapoptotic markers than the free drugs employing qRT-PCR and western blot analysis. The findings demonstrate that CsLTP1 binds strongly to hydrophobic drugs to facilitate their transport, hence improving their therapeutic efficacy revealed by the in-vitro investigations. This study establishes an excellent foundation for developing CsLTP1-based efficient drug delivery system. Graphical presentation of CsLTP1 protein as a drug delivery agent: Hydrophobic anticancer drug molecules bind to the lipid binding hydrophobic cavity of CsLTP1 facilitating their transport across the cell membrane in cancer cells. It resulted into the significant increase in intracellular apoptotic pathway markers thereby enhancing the cellular apoptosis and oxidative stress than the free drug. [Display omitted] •Multiple drug molecules bind stably to the hydrophobic pocket of CsLTP1.•Panobinostat and Vorinostat possess strong affinities to CsLTP1 identified by SPR.•CsLTP1-associated drugs show significantly enhanced therapeutic efficacy.•This study implies CsLTP1 as a potent drug delivery agent.