Thesis title: Nano-Drug Delivery for Cancer Therapy
Abstract
The use of nanomaterials as delivery systems for anticancer drugs represents a promising therapeutic approach that can overcome systemic cytotoxicity of chemotherapy and enhance drug accumulation in tumor site. At the same time, they can be used in diagnostics and therapy. In this study, I evaluated the effects of two types of nanohybrids in different in vitro models of neuroblastoma and colorectal adenocarcinoma. The first nanohybrid (AuNPs-MTX), made of gold nanoparticles functionalized with the synthetic drug Methotrexate (MTX), was tested on two models of human neuroblastoma, called SJNKP and IMR5. The second nanohybrid (SAMNs-BSAO), made of iron oxide nanoparticles and functionalized with an enzyme that belongs to the family of amine oxidases, named Bovine Serum Amine Oxidase (BSAO), was tested on three cell lines of colorectal adenocarcinoma: Caco-2, LoVo WT and LoVo DX. The first nanohybrid, used at three different concentrations (0.5µg/mL, 10 µg/mL, and 50 µg/mL) demonstrated to have a significant cytotoxic effect on neuroblastoma cell lines, with a decrease of 57% in cell viability of SJNKP cells and 51% in IMR5 cells for the lowest concentration (0.5µg/mL) compared to the free drug. Pristine nanoparticles (AuNPs) without MTX, showed to be biocompatible, due to the negligible cytotoxicity in neuroblastoma cells. The second nanohybrid, SAMN-BSAO, showed to have a significant cytotoxicity in Caco-2 cells (25% decrease of viability) compared to controls; preliminary data obtained in LoVo cells showed that LoVo DX had a higher cytotoxic compared to LoVo WT cells. The nanohybrid was able to cross the cell membranes of the three cell models and had a perinuclear localization in Caco-2 cells. Moreover, 35 µg/mL of SAMN@TA@BSAO were able to induce the activation of the antioxidant pathway, with an increase of SOD-1 protein expression. For the first time, BSAO was delivered in all cell lines, maintaining its activity in the intracellular environment. SAMNs, without BSAO, also revealed no significant cytotoxicity in colorectal adenocarcinoma cells. In conclusion, this study demonstrated that both nanohybrids were efficiently delivered in all the cell lines studied, causing cytotoxicity and with a view to future clinical application, their use could be extended for further studies in animal models. These encouraging results suggest new therapeutic strategies for tumors above reported, especially for patients with more aggressive phenotypes who do not respond to chemotherapy treatment and for overcoming multidrug resistance.