Salman A. Alrokayan

Zinc oxide nanoparticles selectively induce apoptosis in human cancer cells through reactive oxygen species

Background Zinc oxide nanoparticles (ZnO NPs) have received much attention for their implications in cancer therapy. It has been reported that ZnO NPs induce selective killing of cancer cells. However, the underlying molecular mechanisms behind the anticancer response of ZnO NPs remain unclear. Methods and results We investigated the cytotoxicity of ZnO NPs against three types of cancer cells (human hepatocellular carcinoma HepG2, human lung adenocarcinoma A549, and human bronchial epithelial BEAS-2B) and two primary rat cells (astrocytes and hepatocytes). Results showed that ZnO NPs exert distinct effects on mammalian cell viability via killing of all three types of cancer cells while posing no impact on normal rat astrocytes and hepatocytes. The toxicity mechanisms of ZnO NPs were further investigated using human liver cancer HepG2 cells. Both the mRNA and protein levels of tumor suppressor gene p53 and apoptotic gene bax were upregulated while the antiapoptotic gene bcl-2 was downregulated in ZnO NP-treated HepG2 cells. ZnO NPs were also found to induce activity of caspase-3 enzyme, DNA fragmentation, reactive oxygen species generation, and oxidative stress in HepG2 cells. Conclusion Overall, our data demonstrated that ZnO NPs selectively induce apoptosis in cancer cells, which is likely to be mediated by reactive oxygen species via p53 pathway, through which most of the anticancer drugs trigger apoptosis. This study provides preliminary guidance for the development of liver cancer therapy using ZnO NPs.

Oxidative stress mediated apoptosis induced by nickel ferrite nanoparticles in cultured A549 cells

Due to the interesting magnetic and electrical properties with good chemical and thermal stabilities, nickel ferrite nanoparticles are being utilized in many applications including magnetic resonance imaging, drug delivery and hyperthermia. Recent studies have shown that nickel ferrite nanoparticles produce cytotoxicity in mammalian cells. However, there is very limited information concerning the toxicity of nickel ferrite nanoparticles at the cellular and molecular level. The aim of this study was to investigate the cytotoxicity, oxidative stress and apoptosis induction by well-characterized nickel ferrite nanoparticles (size 26 nm) in human lung epithelial (A549) cells. Nickel ferrite nanoparticles induced dose-dependent cytotoxicity in A549 cells demonstrated by MTT, NRU and LDH assays. Nickel ferrite nanoparticles were also found to induce oxidative stress evidenced by generation of reactive oxygen species (ROS) and depletion of antioxidant glutathione (GSH). Further, co-treatment with the antioxidant L-ascorbic acid mitigated the ROS generation and GSH depletion due to nickel ferrite nanoparticles suggesting the potential mechanism of oxidative stress. Quantitative real-time PCR analysis demonstrated that following the exposure of A549 cells to nickel ferrite nanoparticles, the level of mRNA expressions of cell cycle checkpoint protein p53 and apoptotic proteins (bax, caspase-3 and caspase-9) were significantly up-regulated, whereas the expression of anti-apoptotic proteins (survivin and bcl-2) were down-regulated. Moreover, activities of caspase-3 and caspase-9 enzymes were also significantly higher in nickel ferrite nanoparticles exposed cells. To the best of our knowledge this is the first report showing that nickel ferrite nanoparticles induced apoptosis in A549 cells through ROS generation and oxidative stress via p53, survivin, bax/bcl-2 and caspase pathways.

Structural and thermal studies of silver nanoparticles and electrical transport study of their thin films

This work reports the preparation and characterization of silver nanoparticles synthesized through wet chemical solution method and of silver films deposited by dip-coating method. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), field emission transmission electron microscopy (FETEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and energy dispersive spectroscopy (EDX) have been used to characterize the prepared silver nanoparticles and thin film. The morphology and crystal structure of silver nanoparticles have been determined by FESEM, HRTEM, and FETEM. The average grain size of silver nanoparticles is found to be 17.5 nm. The peaks in XRD pattern are in good agreement with that of face-centered-cubic form of metallic silver. TGA/DTA results confirmed the weight loss and the exothermic reaction due to desorption of chemisorbed water. The temperature dependence of resistivity of silver thin film, determined in the temperature range of 100-300 K, exhibit semiconducting behavior of the sample. The sample shows the activated variable range hopping in the localized states near the Fermi level.

ZnO nanorod-induced apoptosis in human alveolar adenocarcinoma cells via p53, survivin and bax/bcl-2 pathways: role of oxidative stress

UNLABELLED Zinc oxide (ZnO) nanoparticles (NPs) are increasingly recognized for their utility in biological applications, including biosensor and medicine. However, little is known about the toxicity mechanisms of ZnO nanorods in human cells. This study was designed to investigate the possible mechanisms of apoptosis induced by ZnO nanorods in human alveolar adenocarcinoma (A549) cells. ZnO nanorod was found to induce cytotoxicity, reactive oxygen species (ROS) generation, oxidative stress and activities of caspase-3 & caspase-9 in a dose- and time-dependent manner. Western blot results showed that ZnO nanorods induced the expression of heat shock protein 70, a first-tier marker of cell damage and a cell-cycle checkpoint protein p53. Moreover, pro-apoptotic protein bax was upregulated and the antiapoptotic proteins, survivin and bcl-2, were downregulated in ZnO nanorod exposed cells. In conclusion, our data demonstrates that ZnO nanorod induced apoptosis in A549 cells through ROS and oxidative stress via p53, survivin, bax/bcl-2 and caspase pathways. FROM THE CLINICAL EDITOR This study describes the mechanisms of apoptosis induced by ZnO nanorods in human alveolar adenocarcinoma cells.

Biodegradable polymeric vesicles containing magnetic nanoparticles, quantum dots and anticancer drugs for drug delivery and imaging

We have developed biodegradable polymeric vesicles as a nanocarrier system for multimodal bio-imaging and anticancer drug delivery. The poly(lactic-co-glycolic acid) (PLGA) vesicles were fabricated by encapsulating inorganic imaging agents of superparamagnetic iron oxide nanoparticles (SPION), manganese-doped zinc sulfide (Mn:ZnS) quantum dots (QDs) and the anticancer drug busulfan into PLGA nanoparticles via an emulsion-evaporation method. T2∗-weighted magnetic resonance imaging (MRI) of PLGA-SPION-Mn:ZnS phantoms exhibited enhanced negative contrast with r2∗ relaxivity of approximately 523 s(-1) mM(-1) Fe. Murine macrophage (J774A) cellular uptake of PLGA vesicles started fluorescence imaging at 2 h and reached maximum intensity at 24 h incubation. The drug delivery ability of PLGA vesicles was demonstrated in vitro by release of busulfan. PLGA vesicle degradation was studied in vitro, showing that approximately 32% was degraded into lactic and glycolic acid over a period of 5 weeks. The biodistribution of PLGA vesicles was investigated in vivo by MRI in a rat model. Change of contrast in the liver could be visualized by MRI after 7 min and maximal signal loss detected after 4 h post-injection of PLGA vesicles. Histological studies showed that the presence of PLGA vesicles in organs was shifted from the lungs to the liver and spleen over time.

Apoptosis induction by silica nanoparticles mediated through reactive oxygen species in human liver cell line HepG2.

Silica nanoparticles are increasingly utilized in various applications including agriculture and medicine. In vivo studies have shown that liver is one of the primary target organ of silica nanoparticles. However, possible mechanisms of hepatotoxicity caused by silica nanoparticles still remain unclear. In this study, we explored the reactive oxygen species (ROS) mediated apoptosis induced by well-characterized 14nm silica nanoparticles in human liver cell line HepG2. Silica nanoparticles (25-200μg/ml) induced a dose-dependent cytotoxicity in HepG2 cells. Silica nanoparticles were also found to induce oxidative stress in dose-dependent manner indicated by induction of ROS and lipid peroxidation and depletion of glutathione (GSH). Quantitative real-time PCR and immunoblotting results showed that both the mRNA and protein expressions of cell cycle checkpoint gene p53 and apoptotic genes (bax and caspase-3) were up-regulated while the anti-apoptotic gene bcl-2 was down-regulated in silica nanoparticles treated cells. Moreover, co-treatment of ROS scavenger vitamin C significantly attenuated the modulation of apoptotic markers along with the preservation of cell viability caused by silica nanoparticles. Our data demonstrated that silica nanoparticles induced apoptosis in human liver cells, which is ROS mediated and regulated through p53, bax/bcl-2 and caspase pathways. This study suggests that toxicity mechanisms of silica nanoparticles should be further investigated at in vivo level.

Nickel oxide nanoparticles induce cytotoxicity, oxidative stress and apoptosis in cultured human cells that is abrogated by the dietary antioxidant curcumin.

Nickel oxide nanoparticles (NiO NPs) are increasingly utilized in a number of applications. However, little is known about the toxicity of NiO NPs following exposure to human cells. This study was designed to investigate NiO NPs induced cytotoxicity, oxidative stress and apoptosis in cultured human airway epithelial (HEp-2) and human breast cancer (MCF-7) cells. The results show that cell viability was reduced by NiO NPs and degree of reduction was dose-dependent. NiO NPs were also found to induce oxidative stress in dose-dependent manner indicated by depletion of glutathione and induction of reactive oxygen species and lipid peroxidation. Induction of caspase-3 enzyme activity and DNA fragmentation, biomarkers of apoptosis were also observed in NiO NPs exposed cells. Preventive potential of a dietary antioxidant curcumin against NiO NPs induced toxicity in HEp-2 MCF-7 cells was further examined. We found that co-exposure of curcumin significantly attenuated the cytotoxicity and oxidative stress induced by NiO NPs in both types of cells. This is the first report showing that NiO NPs induced ROS mediated cytotoxicity and apoptosis that is abrogated by curcumin. The pharmacological potential of curcumin against NiO NPs induced toxicity warrants further investigation.

Luminescent mesoporous LaVO4:Eu3+ core-shell nanoparticles: synthesis, characterization, biocompatibility and their cytotoxicity

A general and facile method was used for preparation of water-soluble silica coated LaVO4:Eu3+ core-shell nanoparticles. In the present study, we have discussed and compared the cytotoxicity characteristics of the synthesized LaVO4:Eu3+ and silica coated LaVO4:Eu3+ core-shell nanoparticles. X-ray diffraction (XRD), field-emission transmission electron microscopy (FE-TEM), energy dispersive X-ray analysis (EDX), Fourier-transform infrared spectroscopy (FTIR), UV/Vis absorption spectroscopy and photoluminescence spectroscopic techniques were employed to characterize the structure and morphology of the prepared products. To obtain high aqueous solubility, luminescent LaVO4:Eu3+ nanoparticles were encapsulated with silica groups, giving the nanoparticles a negatively charged surface at physiological pH. The results of XRD confirm the formation of a well-crystallized LaVO4:Eu3+ phase with a tetragonal zircon structure. Optical absorption spectra show that the optical properties of silica-coated LaVO4:Eu3+ core-shell nanoparticles are related to their sizes and shapes. Further, in order to assess cytotoxicity, we investigated whether the LaVO4:Eu3+ nanoparticles could alter biological samples once they enter human H522 and peripheral blood mono nuclear cells (PBMCs). An MTT assay was performed to measure the mitochondrial activity that reflects the number of viable cells. Silica coated LaVO4:Eu3+ core-shell nanoparticles exhibited no significant effect on the viability of both types of cells up to 24 h after exposure. Strikingly, no dose effects were detected, even at highest concentrations.

Targeted anticancer therapy: overexpressed receptors and nanotechnology.

Targeted delivery of anticancer drugs to cancer cells and tissues is a promising field due to its potential to spare unaffected cells and tissues, but it has been a major challenge to achieve success in these therapeutic approaches. Several innovative approaches to targeted drug delivery have been devised based on available knowledge in cancer biology and on technological advancements. To achieve the desired selectivity of drug delivery, nanotechnology has enabled researchers to design nanoparticles (NPs) to incorporate anticancer drugs and act as nanocarriers. Recently, many receptor molecules known to be overexpressed in cancer have been explored as docking sites for the targeting of anticancer drugs. In principle, anticancer drugs can be concentrated specifically in cancer cells and tissues by conjugating drug-containing nanocarriers with ligands against these receptors. Several mechanisms can be employed to induce triggered drug release in response to either endogenous trigger or exogenous trigger so that the anticancer drug is only released upon reaching and preferentially accumulating in the tumor tissue. This review focuses on overexpressed receptors exploited in targeting drugs to cancerous tissues and the tumor microenvironment. We briefly evaluate the structure and function of these receptor molecules, emphasizing the elegant mechanisms by which certain characteristics of cancer can be exploited in cancer treatment. After this discussion of receptors, we review their respective ligands and then the anticancer drugs delivered by nanotechnology in preclinical models of cancer. Ligand-functionalized nanocarriers have delivered significantly higher amounts of anticancer drugs in many in vitro and in vivo models of cancer compared to cancer models lacking such receptors or drug carrying nanocarriers devoid of ligand. This increased concentration of anticancer drug in the tumor site enabled by nanotechnology could have a major impact on the efficiency of cancer treatment while reducing systemic side effects.

Dose-dependent genotoxicity of copper oxide nanoparticles stimulated by reactive oxygen species in human lung epithelial cells.

Copper oxide nanoparticles (CuO NPs) are of great interest in nanoscience and nanotechnology because of their broad industrial and commercial applications. Therefore, toxicity of CuO NPs needs to be thoroughly understood. The aim of this study was to investigate the cytotoxicity, genotoxicity, and oxidative stress induced by CuO NPs in human lung epithelial (A549) cells. CuO NPs were synthesized by solvothermal method and the size of NPs measured under transmission electron microscopy (TEM) was found to be around 23 nm. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide (MTT) and lactate dehydrogenase (LDH) assays showed that CuO NPs (5–15 µg/ml) exert cytotoxicity in A549 cells in a dose-dependent manner. Comet assay suggested concentration-dependent induction of DNA damage due to the exposure to CuO NPs. The comet tail moment was 27% at 15 µg/ml of CuO NPs, whereas it was 5% in control (p < 0.05). The flow cytometry data revealed that CuO NPs induced micronuclei (MN) in A549 cells dose dependently. The frequency of MN was 25/103 cells at 15 µg/ml of CuO NPs, whereas it was 2/103 cells for control. CuO NPs were also found to induce oxidative stress in a concentration-dependent manner, which was indicated by induction of reactive oxygen species (ROS) and lipid peroxidation along with glutathione depletion. Moreover, MN induction and DNA damage were significantly correlated with ROS (R2 = 0.937 for ROS vs. olive tail moment, and R2 = 0.944 for ROS vs. MN). Taken together, this study suggested that CuO NPs induce genotoxicity in A549 cells, which is likely to be mediated through ROS generation and oxidative stress.