We previously showed that folate liposomes of 5FU made from Dipalmitoylphosphatidylcholine (DPPC) induced cell death in HT-29 and HeLa cells more potently than bulk 5FU. Also, a primary 5FU liposomal formulation with phosphatidyl choline (PC) exhibited higher cytotoxicity in murine colon cancer cells. In the present study, optimization of 5FU PC liposome, mechanism of cell death induction in human cancer cell lines and its safety along with other assays have been employed for targeted PC liposomes of 5FU. Liposomes were prepared using thin layer method and optimization of preparation was assessed using central composite design (CCD) of response surface methodology (RSM). Folic acid (FA) was employed as the targeting ligand. Morphology of 5FU loaded liposomes and changes in their thermal behavior were assessed by transmission electron microscopy (TEM) and differential scanning calorimetry (DSC), respectively. In vitro cytotoxicity was explored using MTT assay in HT-29, Caco-2, HeLa and MCF-7 cell lines. Cytotoxicity mechanism of the targeted delivery system was searched through the evaluation of reactive oxygen species (ROS) overproduction, mitochondrial membrane potential (∆Ψm), the release of cytochrome c, the activity of caspase 3/7 and apoptosis and necrosis rate. Liposomes were spherical in shape and 5FU was successfully encapsulated into liposomes rather in an amorphous state. Our interesting results showed that in HT-29 cells targeted liposomes triggered the mitochondrial apoptotic pathway by decreasing the mitochondrial membrane potential, releasing of cytochrome c and promoting the substantial activity of caspase 3/7. In HeLa cells, however, targeted liposomes particularly activated necrosis pathway through the overproduction of ROS. Folate-liposomal 5FU showed significantly higher antitumor efficiency compared to free drug. The results of this study offer new prospects for cancer therapy with reducing systemic drug exposure and associated toxicities.
Keywords: 5-Fluorouracil; Folic acid; Liposome; Response surface methodology; Targeted drug delivery.
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