Calcium electroporation in three cell lines: a comparison of bleomycin and calcium,calcium compounds,and pulsing conditions

Background

Electroporation with calcium (calcium electroporation) can induce ATP depletion-associated cellular death. In the clinical setting, the cytotoxic drug bleomycin is currently used with electroporation (electrochemotherapy) for palliative treatment of tumors. Calcium electroporation offers several advantages over standard treatment options: calcium is inexpensive and may readily be applied without special precautions, as is the case with cytostatic drugs. Therefore, details on the use of calcium electroporation are essential for carrying out clinical trials comparing calcium electroporation and electrochemotherapy.

Methods

The effects of calcium electroporation and bleomycin electroporation (alone or in combination) were compared in three different cell lines (DC-3F, transformed Chinese hamster lung fibroblast; K-562, human leukemia; and murine Lewis Lung Carcinoma). Furthermore, the effects of electrical pulsing parameters and calcium compound on treatment efficacy were determined.

Results

Electroporation with either calcium or bleomycin significantly reduced cell survival (p < 0.0001), without evidence of a synergistic effect. Cellular death following calcium or bleomycin treatment occurred at similar applied voltages, suggesting that similar parameters should be applied. At equimolar concentrations, calcium chloride and calcium glubionate resulted in comparable decreases in cell viability.

Conclusions

Calcium electroporation and bleomycin electroporation significantly reduce cell survival at similar applied voltage parameters. The effect of calcium electroporation is independent of calcium compound.

General significance

This study strongly supports the use of calcium electroporation as a potential cancer therapy and the results may aid in future clinical trials.     

Selective cytotoxicity of intense nanosecond-duration electric pulses in mammalian cells

Background

Nanosecond electric pulses (EP) disrupt cell membrane and organelles and cause cell death in a manner different from the conventional irreversible electroporation. We explored the cytotoxic effect of 10-ns EP (quantitation, mechanisms, efficiency, and specificity) in comparison with 300-ns, 1.8- and 9-μs EP.

Methods

Effects in Jurkat and U937 cells were characterized by survival assays, DNA electrophoresis and flow cytometry.

Results

10-ns EP caused apoptotic or necrotic death within 2–20 h. Survival (S, %) followed the absorbed dose (D, J/g) as: S = αD^(−K), where coefficients K and α determined the slope and the “shoulder” of the survival curve. K was similar in all groups, whereas α was cell type- and pulse duration-dependent. Long pulses caused immediate propidium uptake and phosphatidylserine (PS) externalization, whereas 10-ns pulses caused PS externalization only.

Conclusions

1.8- and 9-μs EP cause cell death efficiently and indiscriminately (LD₅₀ 1–3 J/g in both cell lines); 10-ns EP are less efficient, but very selective (LD₅₀ 50–80 J/g for Jurkat and 400–500 J/g for U937); 300-ns EP show intermediate effects. Shorter EP open propidium-impermeable, small membrane pores (”nanopores”), triggering different cell death mechanisms.

General significance

Nanosecond EP can selectively target certain cells in medical applications like tumor ablation.     

Glucose- and time-dependence of islet amyloid formation in vitro

Islet amyloid contributes to the loss of beta-cell mass in type 2 diabetes. To examine the roles of glucose and time on amyloid formation, we developed a rapid in vitro model using isolated islets from human islet amyloid polypeptide (hIAPP) transgenic mice. Islets from hIAPP transgenic and non-transgenic mice were cultured for up to 7 days with either 5.5, 11.1, 16.7 or 33.3mmol/l glucose. At various time-points throughout the culture period, islets were harvested for determination of amyloid and beta-cell areas, and for measures of cell viability, insulin content, and secretion. Following culture of hIAPP transgenic islets in 16.7 or 33.3mmol/l glucose, amyloid formation was significantly increased compared to 5.5 or 11.1mmol/l glucose culture. Amyloid was detected as early as day 2 and increased in a time-dependent manner so that by day 7, a decrease in the proportion of beta-cell area in hIAPP transgenic islets was evident. When compared to non-transgenic islets after 7-day culture in 16.7mmol/l glucose, hIAPP transgenic islets were 24% less viable, had decreased beta-cell area and insulin content, but displayed no change in insulin secretion. Thus, we have developed a rapid in vitro model of light microscopy-visible islet amyloid formation that is both glucose- and time-dependent. Formation of amyloid in this model is associated with reduced cell viability and beta-cell loss but adequate functional adaptation. It thus enables studies investigating the mechanism(s) underlying the amyloid-associated loss of beta-cell mass in type 2 diabetes.     

Protein kinase C protects from DNA damage-induced necrotic cell death by inhibiting poly(ADP-ribose) polymerase-1

The goal of the current study, conducted in freshly isolated thymocytes was (1) to investigate the possibility that the activation of poly(ADP-ribose) polymerase-1 (PARP-1) in an intact cell can be regulated by protein kinase C (PKC) mediated phosphorylation and (2) to examine the consequence of this regulatory mechanism in the context of cell death induced by the genotoxic agent. In cells stimulated by the PKC activating phorbol esters, DNA breakage was unaffected, PARP-1 was phosphorylated, 1-methyl-3-nitro-1-nitrosoguanidine-induced PARP activation and cell necrosis were suppressed, with all these effects attenuated by the PKC inhibitors GF109203X or G?6976. Inhibition of cellular PARP activity by PKC-mediated phosphorylation may provide a plausible mechanism for the previously observed cytoprotective effects of PKC activators.     

Resveratrol protects cardiomyocytes from oxidative stress through SIRT1 and mitochondrial biogenesis signaling pathways

Reactive oxygen species (ROS) is generated by oxidative stress and plays an important role in various cardiac pathologies. The SIRT1 signaling pathway and mitochondrial biogenesis play essential roles in mediating the production of ROS. SIRT1 activated by resveratrol protects cardiomyocytes from oxidative stress, but the exact mechanisms by which SIRT1 prevents oxidative stress, and its relationship with mitochondrial biogenesis, remain unclear. In this study, it was observed that after stimulation with 50 μM H₂O₂ for 6 h, H9C2 cells produced excessive ROS and downregulated SIRT1. The mitochondrial protein NDUFA13 was also downregulated by ROS mediated by SIRT1. Resveratrol induced the expression of SIRT1 and mitochondrial genes NDUFA1, NDUFA2, NDUFA13 and Mn-SOD. However, the production of these genes was reversed by SIRT1 inhibitor nicotinamide. These results suggest that resveratrol inhibits ROS generation in cardiomyocytes via SIRT1 and mitochondrial biogenesis signaling pathways.     

Polypeptide from Chlamys farreri protects HaCaT cells from UVB-induced apoptosis

A natural polypeptide from marine Chlamys farreri (a kind of scallop) (PCF), has been recently been found to be an effective photoprotective agent against ultraviolet rays B (UVB)-induced mitochondria damage in normal human fibroblasts. To investigate whether PCF has the antiapoptotic effect on human keratinocytes, in the present study, we established an apoptotic model on HaCaT cell line by means of UVB radiance of 30 mJ/cm(2) and compared the effect of different PCF treatments on UVB-radiated cells. Flow cytometry analyses showed that PCF treatment before UVB-irradiation inhibited UVB-induced apoptosis, the loss of mitochondrial membrane potential (Deltapsim) and the increase of free Ca(2+) level in HaCaT cells. In parallel with these results, UVB-irradiation enhanced activities of caspases-3, 8, 9, while this enhancement was inhibited by PCF treatment prior to irradiation. PCF added after irradiation neither reduced UVB-induced activities of the three caspases nor synergized the effect of pre-added PCF. Cellular ultrastructural features obtained from transmission electron microscopy further confirmed the antiapoptotic effect of PCF pre-treatment. It is concluded that the antiapoptotic effect of PCF is not therapeutic but prophylactic. Caspases-3, 8, 9, Deltapsim and calcium are involved in UVB-induced apoptosis, while prophylactic PCF inhibits apoptosis of UVB-irradiated HaCaT cells by blocking the caspases activities, the Deltapsim lost and the elevation of intracellular free Ca(2+) level.     

Cadmium activates CaMK-II and initiates CaMK-II-dependent apoptosis in mesangial cells

Cadmium is a toxic metal that initiates both mitogenic responses and cell death. We show that Cd(2+) increases phosphorylation and activity of Ca(2+)/calmodulin-dependent protein kinase II (CaMK-II) in mesangial cells, in a concentration-dependent manner. Activation is biphasic with peaks at 1-5 min and 4-6 h. Cadmium also activates Erk, but this appears to be independent of CaMK-II. At 10-20 microM, Cd(2+) initiates apoptosis in 25-55% of mesangial cells by 6h. Inhibition of CaMK-II, but not of Erk, suppresses Cd(2+)-induced apoptosis. We conclude that activation of CaMK-II by Cd(2+) contributes to apoptotic cell death, independent of Erk activation.     

Inhibitory effects of anticancer peptide from Mercenaria on the BGC-823 cells and several enzymes

An anti-cancer peptide was purified from the Mercenaria (Meretrix meretrix Linnaeus) by the method of chromatography on Sephadex G-25 and FPLC, and its molecular weight was determined to be 3147 Da by the way of MALDI-TOF mass spectrum. The effects of this peptide on human gastric gland carcinoma cells (BGC-823) and their cytoskeletal morphology were investigated. The results showed that the peptide could inhibit the proliferation of BGC-823 cells and obviously destroy the skeletal structures of the cells. When the concentration of the peptide reached 4.0 microg/ml, the inhibition percentage of the cell growth was about 60%. The effects of this anticancer peptide on the activities of superoxide dismutase (SOD), alkaline phosphatase (ALP) and tyrosinase were studied. The results showed that the peptide activated ALP and SOD, but inhibit the tyrosinase activity. When the concentration of the peptide reached to 0.5 microg/ml, the relative activities of SOD, ALP and tyrosinase were determined to be 188.5%, 122.0% and 27.5%, respectively.     

C-21 steroidal glycosides from the roots of Cynanchum chekiangense and their immunosuppressive activities

Two new C21 steroidal glycosides, chekiangensosides A and B, were isolated from the roots of Cynanchum chekiangense, together with two known compounds. On the basis of chemical evidence and extensive spectroscopic methods, including one-dimensional and two-dimensional NMR, the structures of two new compounds were identified as cynajapogenin A, 3-O-beta-D-glucopyranosyl-(1-->4)-beta-D-cymaropyranosyl-(1-->4)-alpha-L-cymaropyranosyl-(1-->4)-beta-D-cymaropyranoside, and glaucogenin A, 3-O-beta-D-glucopyranosyl-(1-->4)-beta-D-cymaropyranosyl-(1-->4)-alpha-L-cymaropyranosyl-(1-->4)-beta-D-cymaropyranoside, respectively. The two known steroidal glycosides, and were revised. These isolated compounds were tested for their immunological activities in vitro against concanavalin A (Con A)- and lipopolysaccharide (LPS)-induced proliferation of mice splenocytes. Compounds showed immunosuppressive activities in vitro in a dose-dependent manner.     

Characterization of human thioredoxin-like-1: potential involvement in the cellular response against glucose deprivation

The thioredoxin system, composed of thioredoxin (Trx) and thioredoxin reductase (TrxR), emerges as one of the most important thiol-based systems involved in the maintenance of the cellular redox balance. Thioredoxin-like-1 (TXL-1) is a highly conserved protein comprising an N-terminal Trx domain and a C-terminal domain of unknown function. Here we show that TXL-1 is a substrate for the cytosolic selenoprotein TrxR-1. In situ hybridization experiments demonstrates high expression of Txl-1 mRNA in various areas of central nervous system and also in some reproductive organs. Glucose deprivation, but not hydrogen peroxide treatment, reduced the levels of endogenous TXL-1 protein in HEK-293 cell line. Conversely, overexpression of TXL-1 protects against glucose deprivation-induced cytotoxicity. Taken together, the finding that Txl-1 mRNA is highly expressed in tissues which use glucose as a primary energy source and the modulation of TXL-1 levels upon glucose deprivation indicate that TXL-1 might be involved in the cellular response to sugar starvation stress.     

Effect of antimicrobial peptides on ATPase activity and proton pumping in plasma membrane vesicles obtained from mycobacteria

The potential usefulness of antimicrobial peptides (AMPs) as antimycobacterial compounds has not been extensively explored. Although a myriad of studies on AMPs from different sources have been done, some of its mechanisms of action are still unknown. Maganins are of particular interest since they do not lyse non-dividing mammalian cells. In this work, AMPs with well-recognized activity against bacteria were synthesized, characterized, purified and their antimycobacterial activity and influence on ATPase activity in mycobacterial plasma membrane vesicles were assessed. Using bioinformatics tools, a magainin-I analog peptide (MIAP) with improved antimicrobial activity was designed. The influence of MIAP on proton (H(+)) pumping mediated by F(1)F(0)-ATPase in plasma membrane vesicles obtained from Mycobacterium tuberculosis was evaluated. We observed that the antimycobacterial activity of AMPs was low and variable. However, the activity of the designed peptide MIAP against M. tuberculosis was 2-fold higher in comparison to magainin-I. The basal ATPase activity of mycobacterial plasma membrane vesicles decreased approximately 24-30% in the presence of AMPs. On the other hand, the MIAP peptide completely abolished the F(1)F(0)-ATPase activity involved in H(+) pumping across M. tuberculosis plasma membranes vesicles at levels similar to the specific inhibitor N,N' dicyclohexylcarbodiimide. These finding suggest that AMPs can inhibit the H(+) pumping F(1)F(0)-ATPase of mycobacterial plasma membrane that potentially interferes the internal pH and viability of mycobacteria.     

Cotreatment with apicidin overcomes TRAIL resistance via inhibition of Bcr-Abl signaling pathway in K562 leukemia cells

TNF-related apoptosis-inducing ligand (TRAIL) is a pro-apoptotic cytokine that is capable of inducing apoptosis in a wide variety of cancer cells but not in normal cells. Although many cancer cells are sensitive to TRAIL-induced apoptosis, chronic myeloid leukemia (CML) develops resistance to TRAIL. In this study, we investigated whether apicidin, a novel histone deacetylase inhibitor, could overcome the TRAIL resistance in CML-derived K562 cells. Compared to treatment with apicidin or TRAIL alone, cotreatment with apicidin and TRAIL-induced apoptosis synergistically in K562 cells. This combination led to activation of caspase-8 and Bcl-2 interacting domain (Bid), resulting in the cytosolic accumulation of cytochrome c from mitochondria as well as an activation of caspase-3. Treatment with apicidin resulted in down-regulation of Bcr-Abl and inhibition of its downstream target, PI3K/AKT-NF-κB pathway. In addition, apicidin decreased the level of NF-κB-dependent Bcl-x_L, leading to caspase activation and Bid cleavage. These results suggest that apicidin may sensitize K562 cells to TRAIL-induced apoptosis through caspase-dependent mitochondrial pathway by regulating expression of Bcr-Abl and its related anti-apoptotic proteins. Therefore, the present study suggests that combination of apicidin and TRAIL may be an effective strategy for treating TRAIL-resistant Bcr-Abl expressing CML cells.     

Si RNA inhibition of GRP58 associated with decrease in mitomycin C-induced DNA cross-linking and cytotoxicity

The anti-cancer drug mitomycin C is metabolically activated to bind and cross-link DNA. The cross-linking contributes significantly to the cytotoxicity. The complex chemical structure of mitomycin C allows its metabolism by several known (cytosolic NAD(P)H:quinone oxidoreductase and microsomal NADPH:cytochrome P450 reductase) and unknown enzymes. The identification of new enzymes/proteins that metabolize mitomycin C and like drugs is an area of significant research interest since these studies have direct implications in drug development and clinical usage. In the present studies, we have investigated a role of cytosolic glucose regulatory protein GRP58 in mitomycin C-induced DNA cross-linking and cytotoxicity. The control and GRP58 siRNA were transfected in human colon carcinoma HCT116 cells in culture. The transfection of GRP58 siRNA but not control siRNA significantly inhibited GRP58 in human colon carcinoma HCT116 cells. The inhibition of GRP58 led to decrease in mitomycin C-induced DNA cross-linking and cytotoxicity. These results establish a role of GRP58 in mitomycin C-induced DNA cross-linking and cytotoxicity. Site-directed mutagenesis of cysteines to serines in thioredoxin domains of GRP58 and cross-linking assays revealed that both N- and C-terminal thioredoxin domains are required for GRP58-mediated mitomycin C-induced DNA cross-linking. These results suggest that GRP58 might be an important target enzyme for further studies on mitomycin C and similar drug therapy.     

PEP-1-PEA-15 protects against toxin-induced neuronal damage in a mouse model of Parkinson's disease

Background

PEA-15 is abundantly expressed in both neurons and astrocytes throughout the brain. It is a multifunctional protein with the ability to increase cell survival via anti-apoptotic and anti-proliferative properties. However, the function of PEA-15 in neuronal diseases such as Parkinson's disease (PD) remains unclear. In this study, we investigated the protective effects of PEA-15 on neuronal damage induced by MPP⁺ in neuroblastoma SH-SY5Y and BV2 microglia cells and in a MPTP-induced PD mouse model using cell-permeable PEP-1-PEA-15.

Methods

PEP-1-PEA-15 was purified using affinity chromatography. Cell viability and DNA fragmentation were examined by MTT assay and TUNEL staining. Dopaminergic neuronal cell death in the animal model was examined by immunohistochemistry.

Results

PEP-1-PEA-15 transduced into the SH-SY5Y and BV2 cells in a time- and dose-dependent manner. Transduced PEP-1-PEA-15 protected against MPP⁺-induced toxicity by inhibiting intracellular ROS levels and DNA fragmentation. Further, it enhanced the expression levels of Bcl-2 and caspase-3 while reducing the expression levels of Bax and cleaved caspase-3. We found that PEP-1-PEA-15 transduced into the substantia nigra and prevented dopaminergic neuronal cell death in a MPTP-induced PD mouse. Also, we showed the neuroprotective effects in the model by demonstrating that treatment with PEP-1-PEA-15 ameliorated MPTP-induced behavioral dysfunctions and increased dopamine levels in the striatum.

Conclusions

PEP-1-PEA-15 can efficiently transduce into cells and protects against neurotoxin-induced neuronal cell death in vitro and in vivo.

General significance

These results demonstrate the potential for PEP-1-PEA-15 to provide a new strategy for protein therapy treatment of a variety of neurodegenerative diseases including PD.     

Four new C-21 steroidal glycosides from the roots of Stephanotis mucronata and their immunological activities

Four new C-21 steroidal glycoside, stemucronatosides D (1), E (2), F (3), and G (4) were isolated from the roots of Stephanotis mucronata. Their structures were determined on the basis of chemical evidence and extensive spectroscopic methods including one-dimensional and two-dimensional NMR. These isolated compounds were assayed for their immunological activities in vitro against concanavalin A (Con A)- and lipopolysaccharide (LPS)-induced proliferation of mice splenocytes. Compounds 1, 2, and 4 showed immunosuppressive activities in a dose-dependent manner, while compound 3 showed immunomodulating activities.     

Netrin-1 induces proliferation of Schwann cells through Unc5b receptor

Netrin and its receptors, DCC (Deleted in Colorectal Cancer) and Unc5, are proposed to be involved in the axon guidance and neuroglial migration during development. However, accumulating evidence implies that they may also participate in the cell survival and apoptosis. Here, we show that netrin-1 induces proliferation of Schwann cells. Unc5b is the sole receptor expressed in RT4 schwannoma cells and adult primary Schwann cells, and netrin-1 and Unc5b are found to be expressed in the injured sciatic nerve. It was also found that the netrin-1-induced Schwann cell proliferation was blocked by the specific inhibition of Unc5b expression with RNAi. These data suggest that netrin-1 could be an endogenous trophic factor for Schwann cells in the injured peripheral nerves.     

Ellagitannins from Phyllanthus muellerianus (Kuntze) Exell.: Geraniin and furosin stimulate cellular activity, differentiation and collagen synthesis of human skin keratinocytes and dermal fibroblasts

Leaves from Phyllanthus muellerianus (Kuntze) Exell. are traditionally used for wound healing in Western Africa. Aqueous extracts of dried leaves recently have been shown to stimulate proliferation of human keratinocytes and dermal fibroblasts. Within bioassay-guided fractionation the ellagitannins geraniin (1), corilagin (2), furosin (3), the flavonoids quercetin-3-O-β-d-glucoside (isoquercitrin), kaempferol-3-O-β-d-glucoside (astragalin), quercetin-3-O-d-rutinoside (rutin), gallic acid, methyl gallate, caffeic acid, chlorogenic acid, 3,5-dicaffeoylquinic acid and caffeoylmalic acid (phaselic acid) have been identified in P. muellerianus for the first time. Geraniin was shown to be the dominant component of an aqueous extract.Suitable analytical methods for quality control of geraniin in P. muellerianus extract (methanol/water, 70/30) have been developed and validated based on ICH guidelines (ICH-compliant protocol).Geraniin and furosin increased the cellular energy status of human skin cells (dermal fibroblasts NHDF, HaCaT keratinocytes), triggering the cells towards higher proliferation rates, with fibroblasts being more sensitive than keratinocytes. Highest stimulation of NHDF by geraniin was found at 5 μM, and of keratinocytes at 50-100 μM. Furosin stimulated NHDF at about 50 μM, keratinocytes at about 150-200 μM. Necrotic cytotoxicity of geraniin, as measured by LDH release, was observed at 20 μM for NHDF and 150 μM for keratinocytes. Toxicity of furosin - less than that of geraniin - was observed at >400 μM.Furosin and geraniin stimulated the biosynthesis of collagen from NHDF at 50 μM and 5-10 μM respectively. Geraniin at 105 μM significantly stimulated the differentiation in NHEK while furosin had a minor influence on the expression of involucrin and cytokeratins K1 and K10. The study proves clearly that hydrophilic extracts from P. muellerianus and especially the lead compound geraniin exhibit stimulating activity on dermal fibroblasts and keratinocytes, leading to increased cell proliferation, barrier formation and formation of extracellular matrix proteins. From these findings the traditional clinical use of such extracts for wound healing seems to be justified.     

A simple method for production and purification of soluble and biologically active recombinant human leukemia inhibitory factor (hLIF) fusion protein in Escherichia coli

Mouse embryonic stem cells (mESCs) rely on a cytokine named leukemia inhibitory factor (LIF) to maintain their undifferentiated state and pluripotency. However, the progress of mESC research is restricted and limited to highly funded laboratories due to the cost of commercial LIF. Here we presented the homemade hLIF which is biologically active. The hLIF cDNA was cloned into two different vectors in order to produce N-terminal His₆-tag and Trx-His₆-tag hLIF fusion proteins in Origami(DE3) Escherichia coli. The His₆-hLIF fusion protein was not as soluble as the Trx-His₆-hLIF fusion protein. One-step immobilized metal affinity chromatography (IMAC) was done to recover high purity (>95% pure) His₆-hLIF and Trx-His₆-hLIF fusion proteins with the yields of 100 and 200 mg/l of cell culture, respectively. The hLIF fusion proteins were identified by Western blot and verified by mass spectrometry (LC/MS/MS). The hLIF fusion proteins specifically promote the proliferation of TF-1 cells in a dose-dependent manner. They also demonstrate the potency to retain the morphology of undifferentiated mESCs, in that they were positive for mESC markers (Oct-4, Sox-2, Nanog, SSEA-1 and alkaline phosphatase activity). These results demonstrated that the N-terminal fusion tags of the His₆-hLIF and Trx-His₆-hLIF fusion proteins do not interfere with their biological activity. This expression and purification approach to produce recombinant hLIF is a simple, reliable, cost effective and user-friendly method.     

Human erythrocytes and neuroblastoma cells are affected in vitro by Au(III) ions

Gold compounds are well known for their neurological and nephrotoxic implications. However, haematological toxicity is one of the most serious toxic and less studied effects. The lack of information on these aspects of Au(III) prompted us to study the structural effects induced on cell membranes, particularly that of human erythrocytes. AuCl₃ was incubated with intact erythrocytes, isolated unsealed human erythrocyte membranes (IUM) and molecular models of the erythrocyte membrane. The latter consisted of multibilayers of dimyristoylphosphatidylcholine and dimyristoylphosphatidylethanolamine, phospholipids classes located in the outer and inner monolayers of the human erythrocyte membrane, respectively. This report presents evidence that Au(III) interacts with red cell membranes as follows: (a) in scanning electron microscopy studies on human erythrocytes it was observed that Au(III) induced shape changes at a concentration as low as 0.01 μM; (b) in isolated unsealed human erythrocyte membranes Au(III) induced a decrease in the molecular dynamics and/or water content at the glycerol backbone level of the lipid bilayer polar groups in a 5-50 μM concentration range, and (c) X-ray diffraction studies showed that Au(III) in the 10 μm-1 mM range induced increasing structural perturbation only to dimyristoylphosphatidylcholine bilayers. Additional experiments were performed in human neuroblastoma cells SH-SY5Y. A statistically significant decrease of cell viability was observed with Au(III) ranging from 0.1 μM to 100 μM.