Investigation of in vitro cytotoxic effects of heparin coated iron oxide nanoparticles combined with TPP-DCA on human hepatocellular carcinoma cell line HEPG2

Thesis Type: Postgraduate

Institution Of The Thesis: Orta Doğu Teknik Üniversitesi, Faculty of Arts and Sciences, Department of Chemistry, Turkey

Approval Date: 2018




Nanotechnology in medicine involves the applications of nanoparticles and one of the rising field is cancer nanotechnology, which has been increasingly used in cancer diagnostics, imaging, and therapeutic drug delivery. The advantage of the use of the nanoparticles is that, they can be designed to be specific for tumor tissue. This allows increased drug delivery efficiency and reduced off-target toxicities. Iron oxide nanoparticles used in this study are smaller than 100 nm but still it gives an enhanced surface area for the delivery of drugs. Considering the tumor metabolism, targeted therapeutic agents are an alternative anti-tumor treatment which has wide potentials. In most cancer cells, fast growing is related to the disabled mitochondria and consequently cells resist to undergo apoptosis and able to grow in the absence of oxygen. Dichloroacetate (DCA) which is a pyruvate dehydrogenase kinase inhibitor, reverse this process, reduce proliferation and inhibit the tumor growth. However, the DCA dose required to show this effect is significantly high. In order to use a pharmacologically suitable dose, magnetic nanoparticles which can increase the cellular uptake of DCA can be a more efficient alternative. Therefore, in this study, iron oxide nanoparticles (Fe3O4) were first modified with heparin, Dichloroacetate (DCA) is placed inside the heparin layers and in order to use glucose channels, conjugated with 2-deoxy-D-glucose. Triphenlyphosphonium (TPP) was also added to induce the uptake by mitochondria. Internalization of nanoparticles, their cytotoxicity, effects on mitochondrial membrane potential and apoptotic pathways were further analyzed in human hepatocellular carcinoma cell line, HepG2. Uptake assays performed with naked nanoparticles, 1-layer heparin coated TPP-DCA conjugated 2-DG attached nanoparticles, and nanoparticles with 2-layer heparin coated TPP-DCA conjugated with or without 2-DG showed that, heparin coating and 2-DG conjugation significantly increased cellular uptake of particles. Cytotoxicity experiments showed that, tailored nanoparticles increased DCA delivery into cancer cells compared to commercially available Na-DCA drug even when it was conjugated to triphenylphosphonium (TPP). Apoptosis studies indicated that tailored nanoparticles drive cells to undergo apoptosis rather than necrosis. Also, they decreased mitochondrial membrane potential, shifting the hyperpolarization to depolarization indicating that, 2-layer heparin coated TPP-DCA conjugated 2-DG attached nanoparticles not only increased DCA delivery significantly, but also killed hepatocellular carcinoma, HepG2 cells through apoptosis.