Javed Ahmad

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.

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.

Copper oxide nanoparticles induced mitochondria mediated apoptosis in human hepatocarcinoma cells.

Copper oxide nanoparticles (CuO NPs) are heavily utilized in semiconductor devices, gas sensor, batteries, solar energy converter, microelectronics and heat transfer fluids. It has been reported that liver is one of the target organs for nanoparticles after they gain entry into the body through any of the possible routes. Recent studies have shown cytotoxic response of CuO NPs in liver cells. However, the underlying mechanism of apoptosis in liver cells due to CuO NPs exposure is largely lacking. We explored the possible mechanisms of apoptosis induced by CuO NPs in human hepatocellular carcinoma HepG2 cells. Prepared CuO NPs were spherical in shape with a smooth surface and had an average diameter of 22 nm. CuO NPs (concentration range 2–50 µg/ml) were found to induce cytotoxicity in HepG2 cells in dose-dependent manner, which was likely to be mediated through reactive oxygen species generation and oxidative stress. Tumor suppressor gene p53 and apoptotic gene caspase-3 were up-regulated due to CuO NPs exposure. Decrease in mitochondrial membrane potential with a concomitant increase in the gene expression of bax/bcl2 ratio suggested that mitochondria mediated pathway involved in CuO NPs induced apoptosis. This study has provided valuable insights into the possible mechanism of apoptosis caused by CuO NPs at in vitro level. Underlying mechanism(s) of apoptosis due to CuO NPs exposure should be further invested at in vivo level.

ZnO nanoparticles induced oxidative stress and apoptosis in HepG2 and MCF-7 cancer cells and their antibacterial activity.

Liver and breast cancer are the most traumatic diseases because they affect the major organs of the body. Nanomedicine recently emerged as a better option for the treatment of these deadly diseases. As a result, many nanoparticles have been used to treat cancer cell lines. Of the various nanoparticles, zinc oxide exhibits biocompatibility. Therefore, the aim of the present study was to investigate the activity of zinc oxide nanoparticles (ZnO-NPs) against HepG2 and MCF-7 cells. The NPs (∼13±2 nm) were prepared via a non-protonated chemical route and were well-characterized through standard techniques. The study showed that treatment with NPs is notably effective against the proliferation of HepG2 and MCF-7 cancer cells in a dose-dependent manner. The MTT (3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl tetrazolium bromide, a tetrazole) assays revealed the concentration-dependent cytotoxic effects of NPs in range of 2.5-100 μg/ml. HepG2 and MCF-7 cells were exposed to ZnO-NPs and exhibited a significant reduction in their cell viability (95% and 96%; p<0.05) in response to a very low concentration (25 μg/ml) of the ZnO-NPs; this finding was confirmed with FACS (fluorescence-activated cell sorting) data. The reduction in cell viability in response to NP treatment induces cytotoxicity in the cultured cells. The quantitative RT-PCR (real-time polymerase chain reaction) results demonstrate that the exposure of HepG2 cells to ZnO-NPs results in significant upregulation of the mRNA expression level of Bax, p53, and caspase-3 and the down regulation of the anti-apoptotic gene Bcl-2. The NPs were also tested against five pathogenic bacteria through the disk diffusion method, and their antibacterial activities were compared with that of ZnO salt.

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.

Effect of long-term salinity on cellular antioxidants, compatible solute and fatty acid profile of Sweet Annie (Artemisia annua L.)

Impact of long-term salinity and subsequent oxidative stress was studied on cellular antioxidants, proline accumulation and lipid profile of Artemisia annua L. (Sweet Annie or Qinghao) which yields artemisinin (Qinghaosu), effective against cerebral malaria-causing strains of Plasmodium falciparum. Under salinity (0.0-160 mM NaCl), in A. annua, proline accumulation, contents of ascorbate and glutathione and activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione reductase (GR) and catalase (CAT) increased, but the contents of reduced forms of glutathione (GSH) and ascorbate declined. The fatty-acid profiling revealed a major salinity-induced shift towards long-chain and mono-saturated fatty acids. Myristic acid (14:0), palmitoleic acid (16:1), linoleic acid (18:2) and erucic acid (22:1) increased by 141%, 186%, 34% and 908%, respectively, in comparison with the control. Contents of oleic acid (18:1), linolenic acid (18:3), arachidonic acid (22:0) and lignoceric acid (24:0) decreased by 50%, 17%, 44% and 78%, respectively. Thus, in A. annua, salinity declines ascorbate and GSH contents. However, increased levels of proline and total glutathione (GSH+GSSG), and activities of antioxidant enzymes might provide a certain level of tolerance. Modification in fatty-acid composition might be a membrane adaptation to long-term salinity and oxidative stress.

Progress in nanotechnology-based drug carrier in designing of curcumin nanomedicines for cancer therapy: current state-of-the-art

Abstract Comprehensive pharmacological screening of curcumin (CUR) has given the evidence that it is an excellent naturally occurring therapeutic moiety for cancer. It is very well tolerated with insignificant toxicity even after high doses of oral administration. Irrespective of its better quality as an anticancer agent, therapeutic application of CUR is hampered by its extremely low-aqueous solubility and poor bioavailability, rapid clearance and low-cellular uptake. A simple means of breaking up the restrictive factor of CUR is to perk-up its aqueous solubility, improve its bioavailability, protect it from degradation, and metabolism and potentiate its targeting capacity towards the cancer cell. The development in the field of nanomedicine has made excellent progresses toward enhancing the bioavailability of lipophilic drugs like CUR. Nanoparticles (NPs) are capable to deliver the CUR at specific area and thereby prevent it from physiological degradation and systemic clearance. In recent year, an assortment of nanomedicine-based novel drug delivery system has been designed to potentiate the bioavailability of CUR towards anticancer therapy. In this review, we discuss the recent development in the field of nanoCUR (NanoCur), including polymeric micelles, liposome, polymeric NPs, nanoemulsion, nanosuspension, solid lipid NPs (SLNPs), polymer conjugates, nanogel, etc. in anticancer application.

Concentration‐dependent induction of reactive oxygen species, cell cycle arrest and apoptosis in human liver cells after nickel nanoparticles exposure

Due to advent of nanotechnology, nickel nanoparticles (Ni NPs) are increasingly recognized for their utility in various applications including catalysts, sensors and electronics. However, the environmental and human health effects of Ni NPs have not been fully investigated. In this study, we examined toxic effects of Ni NPs in human liver (HepG2) cells. Ni NPs were prepared and characterized by X‐ray diffraction, transmission electron microscopy and dynamic light scattering. We observed that Ni NPs (size, ∼28 nm; concentration range, 25–100 μg/mL) induced cytotoxicity in HepG2 cells and degree of induction was concentration‐dependent. Ni NPs were also found to induce oxidative stress in dose‐dependent manner evident by induction of reactive oxygen species and depletion of glutathione. Cell cycle analysis of cells treated with Ni NPs exhibited significant increase of apoptotic cell population in subG1 phase. Ni NPs also induced caspase‐3 enzyme activity and apoptotic DNA fragmentation. Upregulation of cell cycle checkpoint gene p53 and bax/bcl‐2 ratio with a concomitant loss in mitochondrial membrane potential suggested that Ni NPs induced apoptosis in HepG2 cells was mediated through mitochondrial pathway. This study warrants that applications of Ni NPs should be carefully assessed as to their toxicity to human health.

Influence of sulfur and cadmium on antioxidants, phytochelatins and growth in Indian mustard

Sulphur(S)-deficiency is emerging as a major problem for agricultural productivity. Cadmium (Cd) exerts its phytotoxicity against defence, growth and development. S-rich compounds (glutathione, phytochelatins, etc.) limit the impacts of Cd-toxicity. We investigated what happens during S-deficiency and Cd exposure (dual stress) in mustard. Major findings were: S-deficiency increases the susceptibility of plants to Cd-generated oxidative damage and modulates the AsA-GSH antioxidant cycle; SOD is not the first line of defence against metal stress and S-rich metabolites play a prime role; S-deprived plants are more prone to Cd and oxidative stress; and great loss is incurred to defence modules and growth under dual stress, restricting the efficiency of phytoremediation.