Amphipathic silica nanoparticles induce cytotoxicity through oxidative stress mediated and p53 dependent apoptosis pathway in human liver cell line HL-7702 and rat liver cell line BRL-3A.

The aim of this study was to evaluate the potential cytotoxicity and the underlying mechanism of amphipathic silica nanoparticles (SiO2 NPs) exposure to human normal liver HL-7702 cells and rat normal liver BRL-3A cells. Prior to the cellular studies, transmission electron microscopy (TEM), dynamic light scattering (DLS), and X ray diffraction (XRD) were used to characterize SiO2 NPs, which proved the amorphous nature of SiO2 NPs with TEM diameter of 19.8±2.7nm. Further studies proved that exposure to SiO2 NPs dose-dependently induced cytotoxicity as revealed by cell counting kit (CCK-8) and lactate dehydrogenase (LDH) assays, with more severe cytotoxicity in HL-7702 cells than BRL-3A cells. Reactive oxygen species (ROS) and glutathione (GSH) assays showed elevated oxidative stress in both cells. Morphological studies by microscopic observation, Hochest 33258 and AO/EB staining indicated significant apoptotic changes after the cells being exposed to SiO2 NPs. Further studies by western blot indicated that SiO2 NPs exposure to both cells up-regulated p53, Bax and cleaved caspase-3 expression and down-regulated Bcl-2 and caspase-3 levels. Activated caspase-3 activity detected by colorimetric assay kit and caspase-3/7 activity detected by fluorescent real-time detection kit were significantly increased by SiO2 NPs exposure. In addition, antioxidant vitamin C significantly attenuated SiO2 NPs-induced caspase-3 activation, which indicated that SiO2 NPs-induced oxidative stress was involved in the process of HL-7702 and BRL-3A cell apoptosis. Taken together, these results suggested that SiO2 NPs-induced cytotoxicity in HL-7702 and BRL-3A cells was through oxidative stress mediated and p53, caspase-3 and Bax/Bcl-2 dependent pathway and HL-7702 cells were more sensitive to SiO2 NPs-induced cytotoxicity than BRL-3A cells.

Zuo D ，Duan Z ，Jia Y ，Chu T ，He Q ，Yuan J ，Dai W ，Li Z ，Xing L ，Wu Y ... -  《-》

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.

Ahmad J ，Ahamed M ，Akhtar MJ ，Alrokayan SA ，Siddiqui MA ，Musarrat J ，Al-Khedhairy AA ... -  《-》

Nano-SiO2 induces apoptosis via activation of p53 and Bax mediated by oxidative stress in human hepatic cell line.

Nanoparticles such as nano-SiO(2) are increasingly used in food, cosmetics, diagnosis, imaging and drug delivery. However, toxicological data of nano-SiO(2) on hepatic cells in vitro and their detailed molecular mechanisms still remain unclear. In order to assess toxicity of nano-SiO(2), L-02 cells were exposed to 0.2, 0.4 and 0.6 mg/ml of SiO(2) colloids (21, 48 and 86 nm) for 12, 24, 36 and 48h. Lactate dehydrogenase released from damaged cells were quantified, cellular ultrastructural organization was observed, and the levels of reactive oxygen species (ROS), lipid peroxidation and glutathione were measured. Apoptosis induced by 21 nm SiO(2) was characterized by annexin V-FITC/PI staining and DNA ladder assay. Furthermore, apoptosis related proteins such as p53, Bax and Bcl-2 were analyzed by using western blot analysis. Our data indicated that nano-SiO(2) caused cytotoxicity in size, dose and time dependent manners. Oxidative stress and apoptosis were induced by exposure to 21 nm SiO(2). Moreover, the expression of p53 and Bax was increased in time and dose dependent patterns, whereas the expression of Bcl-2 was not significantly changed. In conclusion, ROS-mediated oxidative stress, the activation of p53 and up-regulation of Bax/Bcl-2 ratio are involved in mechanistic pathways of 21 nm SiO(2) induced apoptosis in L-02 cells.

Ye Y ，Liu J ，Xu J ，Sun L ，Chen M ，Lan M ... -  《-》

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.

Ahamed M ，Akhtar MJ ，Siddiqui MA ，Ahmad J ，Musarrat J ，Al-Khedhairy AA ，AlSalhi MS ，Alrokayan SA ... -  《-》

Cobalt iron oxide nanoparticles induce cytotoxicity and regulate the apoptotic genes through ROS in human liver cells (HepG2).

Cobalt iron oxide (CoFe2O4) nanoparticles (CIO NPs) have been one of the most widely explored magnetic NPs because of their excellent chemical stability, mechanical hardness and heat generating potential. However, there is limited information concerning the interaction of CIO NPs with biological systems. In this study, we investigated the reactive oxygen species (ROS) mediated cytotoxicity and apoptotic response of CIO NPs in human liver cells (HepG2). Diameter of crystalline CIO NPs was found to be 23nm with a band gap of 1.97eV. CIO NPs induced cell viability reduction and membrane damage, and degree of induction was dose- and time-dependent. CIO NPs were also found to induce oxidative stress revealed by induction of ROS, depletion of glutathione and lower activity of superoxide dismutase enzyme. Real-time PCR data has shown that mRNA level of tumor suppressor gene p53 and apoptotic genes (bax, CASP3 and CASP9) were higher, while the expression level of anti-apoptotic gene bcl-2 was lower in cells following exposure to CIO NPs. Activity of caspase-3 and caspase-9 enzymes was also higher in CIO NPs exposed cells. Furthermore, co-exposure of N-acetyl-cysteine (ROS scavenger) efficiently abrogated the modulation of apoptotic genes along with the prevention of cytotoxicity caused by CIO NPs. Overall, we observed that CIO NPs induced cytotoxicity and apoptosis in HepG2 cells through ROS via p53 pathway. This study suggests that toxicity mechanisms of CIO NPs should be further investigated in animal models.

Ahamed M ，Akhtar MJ ，Khan MAM ，Alhadlaq HA ，Alshamsan A ... -  《-》