Aims: To develop an estrone-targeted d-alpha-tocopherol polyethylene glycol 1000 succinate (TPGS)-based liposomal system for enhanced intracellular delivery of doxorubicin (DOX). Materials & methods: Zetasizer, transmission electron microscopy, energy dispersive x-ray, Fourier-transform infrared spectroscopy, differential scanning calorimetry, x-ray diffraction, confocal laser scanning microscopy and FACS analysis were used for formulation characterization and evaluation. Results: The DOX-LIPO-TPGS and DOX-LIPO-TPGS-estrone formulations had vesicle sizes (117.6 ± 3.51; 144 ± 5.00 nm), zeta potential (-36.4 ± 0.75; -35.8 ± 0.76), polydispersity index (0.123 ± 0.005; 0.169 ± 0.005) and percent entrapment efficiency (73.56 ± 3.55; 77.16 ± 3.83%) with improved cytotoxicity and cellular uptake, confirming the targeted potential of the developed formulations. Conclusion: The results suggest that the developed liposomal formulation with desired characteristics is potentially capable of nonimmunogenic, site-specific drug delivery to targeted cancer sites and reduced DOX-associated cardiac toxicity.
Keywords: TPGS; breast cancer; doxorubicin; estrogen receptor; liposome.
Doxorubicin (DOX) is an effective chemotherapy drug to treat breast cancer. However, DOX can cause unwanted side effects such as damage to the heart. This is due to side effects in healthy body tissues. This study was designed to develop nanoparticles that target cancer cells specifically to improve the delivery of DOX to these cells and prevent side effects elsewhere. Nanoparticles called liposomes were used as the platform for delivering DOX. Liposomes are sometimes coated with d-alpha-tocopherol polyethylene glycol 1000 succinate (TPGS), a synthetic vitamin D derivative. This helps the liposome evade the immune system and release the drug more effectively. TPGS was tethered with estrone (ES), a type of estrogen. Certain breast cancer cells have many more estrogen receptors on their cell surface than healthy cells. TPGS-ES was coated on DOX-loaded liposomes to achieve enhanced intracellular delivery of DOX to breast cancer cells specifically. These liposomes were called DOX-LIPO-TPGS-ES. This liposome proved more toxic to cells in a breast cancer cell line than free DOX or liposomes without tethered ES. When tested in rats, DOX-LIPO-TPGS-ES showed increased tumor uptake compared with free DOX or liposomes without tethered ES. Rats treated with either liposomal drug showed normal levels of key markers associated with heart function, whereas those treated with free DOX showed increased levels of these markers. These results suggest that DOX-LIPO-TPGS-ES is capable of highly targeted delivery of DOX with limited side effects.