Uptake and Toxicity of Copper Oxide Nanoparticles in C6 Glioma Cells

Abstract

Copper oxide nanoparticles (CuO-NPs) are frequently used for many technical applications, but are also known for their cell toxic potential. In order to investigate a potential use of CuO-NPs as a therapeutic drug for glioma treatment, we have investigated the consequences of an application of CuO-NPs on the cellular copper content and cell viability of C6 glioma cells. CuO-NPs were synthesized by a wet-chemical method and were coated with dimercaptosuccinic acid and bovine serum albumin to improve colloidal stability in physiological media. Application of these protein-coated nanoparticles (pCuO-NPs) to C6 cells caused a strong time-, concentration- and temperature-dependent copper accumulation and severe cell death. The observed loss in cellular MTT-reduction capacity, the loss in cellular LDH activity and the increase in the number of propidium iodide-positive cells correlated well with the specific cellular copper content. C6 glioma cells were less vulnerable to pCuO-NPs compared to primary astrocytes and toxicity of pCuO-NPs to C6 cells was only observed for incubation conditions that increased specific cellular copper contents above 20 nmol copper per mg protein. Both cellular copper accumulation as well as the pCuO-NP-induced toxicity in C6 cells were prevented by application of copper chelators, but not by endocytosis inhibitors, suggesting that liberation of copper ions from the pCuO-NPs is the first step leading to the observed toxicity of pCuO-NP-treated glioma cells.

Copper Oxide Nanoparticles Stimulate Cytotoxicity and Apoptosis in Glial Cancer Cell Line

“…Our findings are in agreement with previous studies. [13][14][15]28 Although, there is a significant variation in the ability of both particles to alter cell cytotoxicity, the differences in cytotoxicity of each concentration of CuO-NPs is not certain as previously reported for somato sensory neurons of a rat in cell culture. 29 The IC 50 decreased by increasing particle size, however, the decrease was nonsignificant.…”

“…8 Earlier studies showed potent cytotoxic, genotoxic and toxicological activities of CuNPs and even, toxic effects of various types of nanoparticles in C6 glioma cancer cells. 15,22,25 Thus, we first characterized the synthesized CuO NPs for better interpretation of results. The SEM images and zeta size reconfirmed the 30 and 60 nm sizes of CuO NPs, respectively.…”

“…8 Various studies have reported an increased cytotoxic and genotoxic potential as well as an intense pro-inflammatory responses of CuO NPs in vivo 9,10 and in cultured cell lines. [11][12][13][14][15] Oxidative stress is often used to describe the toxicity of cells associated with particle exposure. Because of their unique features such as size, morphology, solubility, surface area as well as their ability to associate with biomolecules from the environment to form a protein and interactions of the particles with cellular membranes, uptake and intracellular bioavailability, can finally lead to elevated levels of reactive oxygen species (ROS).…”

Cupric Oxide Nanoparticles Induce Cellular Toxicity in Liver and Intestine Cell Lines

“…Luo et al indicated CuO-NPs induced a decrease in viability, migration inhibition, G2/M phase cycle arrest, and especially mitogen-activated protein kinase activation in human keratinocytes and mouse embryonic fibroblasts. 27 The cell viability of CuO-NPs decreased in mouse embryonic fibroblasts (48% at 10 µg/mL), 12 and neuroblastoma (37% at 400 µg/mL) cells, 28 in human lung epithelial (93% at 20 µg/cm 2 and 50% at 15 µg/mL), 29,30 airway epithelial (60% at 80 µg/cm 2 ), 31 alveolar adenocarcinomas epithelial (75% at 11 µg/mL), 32 neuroblastoma (60%-70% at 0.01-10 µM), neuroglioma (25%-60% at 0.01-10 µM), 33 C6 glioblastoma (10-1000 µM), 34 cardiac microvascular endothelial, 15 lymphocytes (50% at 0.04 mM), 35 and colon cancer (50% at 40 µg/ mL)cell lines. 36 Muoth et al reported CuO-NPs caused a decrease in human chorionic gonadotropin release and microtissue viability in a 3D co-culture cell model of placental fibroblasts surrounded by a trophoblast cell.…”

Iron-Doping of Copper Oxide Nanoparticles Lowers Their Toxic Potential on C6 Glioma Cells

“…However, CuO-NPs are rapidly dissolving [23,24] and they release ionic copper even in the absence of cells [25][26][27]. Therefore, the copper ions released from dispersed CuO-NPs have been considered to strongly contribute to the copper toxicity [28,29] and to the antibacterial effects [24] described for CuO-NPs. However, at least for glioma cells evidence has also been provided for a direct contribution of nanoparticulate copper in the cell toxicity observed after application of CuO-NPs [30].…”