PCBs enhance MDA-MB-231 breast cancer cell metastases <i>in vivo</i>.

<p>(A) The occurrence of metastases in all organs tested in the PCB-treated mice and vehicle control mice. Metastases were examined using the Xenogen 2000 and the IVIS software as previously described <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0011272#pone.0011272-Liu1" target="_blank">[16]</a>. (B) The quantified data of metastatic tumors (reflected by photon flux, photons/sec <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0011272#pone.0011272-Liu1" target="_blank">[16]</a>) in mouse skeleton (n = 4). (C) Representative images of metastases in mouse liver, lung and skeleton from the bioluminescent imaging.</p

The cytotoxicity induced by PCBs on MDA-MB-231 cells.

<p>(A) Phase-contrast images of cell morphology from MDA-MB-231 cells treated with/without the PCB mix at 60 nM for 24 hrs. Original maginification, ×200. (B) FACS analysis of apoptosis induced by PCBs at 60 nM for 24 hrs in MDA-MB-231 cells using FITC-Annexin V and PI stains. Early apoptotic cells (lower right), necrotic cells (upper left) and late apoptotic/necrotic cells (upper right) are shown as arrows indicate.</p

The signaling stimulated by PCBs in MDA-MB-231 cells.

<p>(A) The relative ROCK activity and Western blot analysis of P-MLC in MDA-MB-231 cells treated with the PCB mix (30 nM) with or without the ROCK inhibitor, Y27632 (10 µM) for 24 hrs (n = 3). (B) ROS production in MDA-MB-231 cells upon PCB treatment. DCF fluorescence in cells were measured by FACS analysis after 6-hr PCB treatment with or without β-ME (14.3 µM) (n = 3). (C) The relative ROCK activity and Western blot analysis of P-MLC in cells upon PCB treatment for 6 hrs with or without β-ME (n = 3). *, P<0.05, compared with the vehicle control and the PCBs+β-ME group. The intensities of autoradiogram in Western blots were quantified with Image J (rsbweb.nih.gov/ij). The quantified data for P-MLC were normalized to those of GAPDH.</p

PCBs enhance cell migration in breast cancer cells.

<p>Cell motility was examined from a transwell migration assay in MCF-7 and MDA-MB-231 cells treated with the PCB mix at 30 or 60 nM for 24 hrs. After the DAPI staining (blue), two images were randomly taken from three individual replicates under a microscope, and transmigrated cells in the chamber filters in each image were counted. Representative images for MCF-7 (A) and MDA-MB-231 (B) cells are shown, and the numbers of transmigrated cells were quantified (n = 6). *, P<0.001, compared with the vehicle control and the 60 nM group.</p

A schematic of PCB-induced signaling in breast cancer cells.

<p>At low concentrations, PCBs activate ROCK kinase activity to regulate the actin-myosin-dependent contraction by phosphorylating motor proteins, such as the regulatory MLC. The resulting effect of ROCK activation leads to increased cell motility and potentially metastasis. At high concentrations, PCBs cause cell death via apoptosis, which may be dependent on ROS or not.</p

Computational Investigations of the Interaction between the Cell Membrane and Nanoparticles Coated with a Pulmonary Surfactant

When inhaled nanoparticles (NPs) come into the deep lung, they develop a biomolecular corona by interacting with the pulmonary surfactant. The adsorption of the phospholipids and proteins gives a new biological identity to the NPs, which may alter their subsequent interactions with cells and other biological entities. Investigations of the interaction between the cell membrane and NPs coated with such a biomolecular corona are important in understanding the role of the biofluids on cellular uptake and estimating the dosing capacity and the nanotoxicology of NPs. In this paper, using dissipative particle dynamics, we investigate how the physicochemical properties of the coating pulmonary surfactant lipids and proteins affect the membrane response for inhaled NPs. We pinpoint several key factors in the endocytosis of lipid NPs, including the deformation of the coating lipids, coating lipid density, and ligand–receptor binding strength. Further studies reveal that the deformation of the coating lipids consumes energy but on the other hand promotes the coating ligands to bind with receptors more tightly. The coating lipid density controls the amount of the ligands as well as the hydrophobicity of the lipid NPs, thus affecting the endocytosis kinetics through the specific and nonspecific interactions. It is also found that the hydrophobic surfactant proteins associated with lipids can accelerate the endocytosis process of the NPs, but the endocytosis efficiency mainly depends on the density of the coating surfactant lipids. These findings can help understand how the pulmonary surfactant alters the biocompatibility of the inhaled NPs and provide some guidelines in designing an NP complex for efficient pulmonary drug delivery

Multihierarchically Profiling the Biological Effects of Various Metal-Based Nanoparticles in Macrophages under Low Exposure Doses

Thus far, tremendous efforts have been made to understand the biosafety of metal-based nanoparticles (MNPs). Nevertheless, most previous studies focused on specific adverse outcomes of MNPs at unrealistically high concentrations with little relevance to the National Institute for Occupational Safety and Health (NIOSH) exposure thresholds, and failed to comprehensively evaluate their toxicity profiles. To address these challenges, we here endeavored to multihierarchically profile the hazard effects of various popularly used MNPs in macrophages under low exposure doses. At these doses, no remarkable cell viability drop and cell death were induced. However, a cellular antioxidant defense system was seen to be initiated in cells by all MNPs even at these low concentrations, albeit to a differential extent and through different pathways, as reflected by differential induction of the antioxidant enzymes and Nrf2 signaling. Regarding inflammation, rare earth oxide nanomaterials (REOs) except nCeO₂ greatly increased IL-1β secretion in a NLRP3 inflammasome-dependent manner. By contrast, six REOs, AgNP-5nm, nFe₂O₃, nFe₃O₄, and nZnO were found to elevate TNF-α concentration through post-transcriptional regulation. Moreover, all MNPs except nCeO₂ drastically altered cellular membrane/cytoskeleton meshwork, but leading to different outcomes, with condensed cellular size and reduced numbers of protrusions by REOs and elongated protrusions by other MNPs. Consequently, REOs (e.g., nDy₂O₃ and nSm₂O₃) impaired phagocytosis of macrophages, and other MNPs (such as AgNP-25nm and nZnO) reversely enhanced macrophagic phagocytosis. Alterations of membrane and cytoskeleton meshwork induced by these MNPs also caused disordered membrane potential and calcium ion flux. Collectively, our data profiled the biological effects of different MNPs in macrophages under low exposure doses, and deciphered a complex network that links multiparallel pathways and processes to differential adverse outcomes

Susceptibility of Overweight Mice to Liver Injury as a Result of the ZnO Nanoparticle-Enhanced Liver Deposition of Pb²⁺

The prevalence of the applications of nanomaterials in consumer products and water treatment facilities increases the chance that humans will be exposed to both nanoparticles and environmental pollutants such as heavy metals. Co-exposure to nanoparticles and heavy metals may adversely affect human health, especially in susceptible populations such as overweight subjects. To evaluate the impact of such co-exposures, we orally administered zinc oxide nanoparticles (ZNPs; 14 or 58 nm) and/or Pb­(Ac)₂ at tolerable doses to both healthy overweight and healthy normal weight mice. The ZNPs enhanced the deposition of Pb in all major organs in the overweight mice compared with that in the normal mice. As a result, higher levels of hepatic reactive oxygen species, pro-inflammatory cytokines, and liver injury were observed in the overweight mice but not in the normal weight mice. Our findings underscore a potentially enhanced risk of nanoparticle/heavy metal co-exposure in the susceptible overweight population

Crucial Role of Lateral Size for Graphene Oxide in Activating Macrophages and Stimulating Pro-inflammatory Responses in Cells and Animals

Graphene oxide (GO) is increasingly used in biomedical applications because it possesses not only the unique properties of graphene including large surface area and flexibility but also hydrophilicity and dispersibility in aqueous solutions. However, there are conflicting results on its biocompatibility and biosafety partially due to large variations in physicochemical properties of GO, and the role of these properties including lateral size in the biological or toxicological effects of GO is still unclear. In this study, we focused on the role of lateral size by preparing a panel of GO samples with differential lateral sizes using the same starting material. We found that, in comparison to its smaller counterpart, larger GO showed a stronger adsorption onto the plasma membrane with less phagocytosis, which elicited more robust interaction with toll-like receptors and more potent activation of NF-κB pathways. By contrast, smaller GO sheets were more likely taken up by cells. As a result, larger GO promoted greater M1 polarization, associated with enhanced production of inflammatory cytokines and recruitment of immune cells. The <i>in vitro</i> results correlated well with local and systemic inflammatory responses after GO administration into the abdominal cavity, lung, or bloodstream through the tail vein. Together, our study delineated the size-dependent M1 induction of macrophages and pro-inflammatory responses of GO <i>in vitro</i> and <i>in vivo</i>. Our data also unearthed the detailed mechanism underlying these effects: a size-dependent interaction between GO and the plasma membrane

Green Algae as Carriers Enhance the Bioavailability of ¹⁴C‑Labeled Few-Layer Graphene to Freshwater Snails

The waterborne exposure of graphene to ecological receptors has received much attention; however, little is known about the contribution of food to the bioaccumulation potential of graphene. We investigated the effect of algal food on the uptake and distribution of ¹⁴C-labeled few-layer graphene (FLG) in freshwater snails, a favorite food for Asian people. In a water-only system, FLG (∼158 μg/L) was ingested by and accumulated in the snails. Adding algae to the water significantly enhanced FLG accumulation in the snails, with a bioaccumulation factor of 2.7 (48 h exposure). Approximately 92.5% of the accumulated FLG was retained in the intestine; in particular, the accumulated FLG in the intestine was able to pass through the intestinal wall and enter the intestinal epithelial cells. Of them, 1.3% was subsequently transferred/internalized to the liver/hepatocytes, a process that was not observed in the absence of the algae. Characterizations data further suggested that both of the extra- and intracellular FLG in the algae (the algae-bound fraction was 30.2%) significantly contributed to the bioaccumulation. Our results provide the first evidence that algae as carriers enhanced FLG bioavailability to the snails, as well as the potential of FLG exposure to human beings through consuming the contaminated snails