| Description |
The targeting of subcellular organelles offers an enhanced therapeutic effect for both small molecules and biologics. The main theme of this research is to use subcellular targeting to elicit or enhance a therapeutic effect, which leads to the hypothesis that targeting specific organelles in a cell will lead to better drug delivery and improvements in disease therapy. In this study, we focused on targeting the mitochondria, nucleus, and proteasome. A small molecule, vitamin E, was targeted to the mitochondria by conjugating it with a triphenylphosphonium cation (forming MitoE) taking advantage of the mitochondrial transmembrane potential. MitoE was concentrated in the myocardial mitochondrial of treated mice. It also reduced oxidative stress in hyperglycemic endothelial cells. In addition, the adiponectin protein was used to reduce the oxidative stress in the mitochondria via cAMP/PKA pathway. A new formulation containing adiponectin was developed using a biodegradable triblock copolymer, which forms a hydrogel at body temperature. The goal was to maintain a controlled release of adiponectin from the hydrogel while preserving its antioxidant activity. The mitochondria were also targeted to deliver the tumor suppressor p53 to induce apoptosis in breast cancer cells via binding to Bcl-XL. p53 was targeted to the outer surface of the mitochondria via fusing to the mitochondrial signal (MTS) from Bcl- XL (XL). It was also inserted into the outer membrane, inner membrane, and matrix by fusing the MTSs from TOM20 (TOM), cytochrome c oxidase (CCO), and ornithine iv transcarbamylase (OTC), respectively. The p53-XL construct was the most promising in inducing apoptosis through the p53/Bcl-XL pathway. In addition to the mitochondria, proteasomal targeting was explored taking advantage of the p53/MDM2 degradation pathway. The designed construct contained a nuclear export signal (NES), a nuclear localization signal (NLS), a ligand binding domain (LBD), and p53. The construct targeted the cytoplasm in the absence of ligand and translocated to the proteasome upon ligand induction. This proteasomal protein switch offers novel treatment therapies for diseases caused by cytoplasmic oncogenic/aberrant proteins. In summary, this dissertation offers a better understanding on subcellular delivery. The focus on targeting subcellular organelles takes therapeutic delivery to the next level, and may lead to improvements in disease therapy. |
