Investigation of cerium oxide nanoparticles as a targeted therapeutic in human cancer cells

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Copyright: Vassie, James
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Abstract
Cerium oxide nanoparticles (CNPs) possess catalytic antioxidant properties and are capable of scavenging reactive oxygen species (ROS), which are elevated in numerous pathologies, including cancer. The aims of this thesis were to characterise CNPs (3-94 nm) functionalised with the cancer-targeting ligand, folic acid (FA) and the fluorophore, FITC, identify their mechanisms of uptake and intracellular trafficking, and determine whether CNPs were capable of modulating ROS and the ROS-dependent expression of the angiogenic markers VEGF-A, FGF-2 and perlecan in SKOV3 ovarian and WiDr colon human cancer cells. Flame spray-synthesised CNPs were successfully modified with FA and FITC via the aminosilane linker, APTES and it was demonstrated that functionalisation efficiency increased with particle diameter, despite the inverse relationship between their total surface area and diameter. The conjugation of FA and FITC to CNPs remained stable in vitro and neither CNPs nor FA-CNPs were found to be cytotoxic in either cell line. It was demonstrated that SKOV3 and WiDr cells expressed folate receptor-alpha (FR-alpha) and that FA significantly enhanced the uptake of FITC-CNPs in both cell lines. Using inhibitors for the active endocytic pathways clathrin, caveolae and macropinocytosis, as well as a non-specific uptake inhibitor, it was demonstrated that all active and passive uptake pathways were utilised in the endocytosis of FITC-CNPs and FA-FITC-CNPs in both cell lines, and that the combinations of pathways involved were dependent on the particle size, surface chemistry and cell type. This finding was confirmed by studying their colocalisation with clathrin, caveolin-1 and lysosomes. Interestingly, the minimal level of colocalisation of FA-FITC-CNPs with lysosomes suggested the uptake of FA-FITC-CNPs occurred via monovalent interactions with FR-alpha. ROS were scavenged more effectively by 14 and 94 nm CNPs compared to 3 and 7 nm CNPs in both cell lines. Additionally, FA-CNPs were more effective scavengers of ROS compared with bare CNPs. Both cell lines expressed significant quantities of perlecan and its expression was modulated by bare CNPs and FA-CNPs. In both cell lines, perlecan expression was significantly reduced by FA-CNPs. It is clear from this thesis that FA-CNPs show promise as a targeted therapeutic in ovarian and colon cancers.
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Author(s)
Vassie, James
Supervisor(s)
Lord, Megan
Whitelock, John
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Publication Year
2016
Resource Type
Thesis
Degree Type
PhD Doctorate
UNSW Faculty
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