Hypoxia enhances motility and EMT through the Na+/H+ exchanger NHE-1 in MDA-MB-231 breast cancer cells.

Breast cancer metastasis is the leading cause of cancer-related deaths. Hypoxia in the tumor mass is believed to trigger cell migration, which is involved in a crucial process of breast cancer metastasis. However, the molecular mechanisms underlying aggressive behavior under hypoxic conditions have not been fully elucidated. Here, we demonstrate the significant motility of MDA-MB-231 cells cultured under hypoxic conditions compared to that of cells cultured under normoxic conditions. MDA-MB-231 cells under hypoxic conditions showed a significant increase in Na+/H+ exchanger isoform 1 (NHE1) expression level, which was observed to co-locate in lamellipodia formation. Inhibition of NHE1 significantly suppressed the intracellular pH and the expression of mesenchymal markers, thereby blocking the high migration activity in hypoxia. Moreover, treatment with ciglitazone, a potent and selective peroxisome proliferator-activated receptor γ (PPARγ) agonist, modulated hypoxia-enhanced motion in cells via the repression of NHE1. These findings highlight that NHE1 is required for migratory activity through the enhancement of epithelial-mesenchymal transition (EMT) in MDA-MB-231 cells under hypoxic conditions, and we propose new drug repurposing strategies targeting hypoxia based on NHE1 suppression by effective usage of PPARγ agonists.

Light-Induced Condensation of Biofunctional Molecules around Targeted Living Cells to Accelerate Cytosolic Delivery.

The light-induced force and convection can be enhanced by the collective effect of electrons (superradiance and red shift) in high-density metallic nanoparticles, leading to macroscopic assembly of target molecules. We here demonstrate application of the light-induced assembly for drug delivery system with enhancement of cell membrane accumulation and penetration of biofunctional molecules including cell-penetrating peptides (CPPs) with superradiance-mediated photothermal convection. For induction of photothermal assembly around targeted living cells in cell culture medium, infrared continuous-wave laser light was focused onto high-density gold-particle-bound glass bottom dishes exhibiting plasmonic superradiance or thin gold-film-coated glass bottom dishes. In this system, the biofunctional molecules can be concentrated around the targeted living cells and internalized into them only by 100 s laser irradiation. Using this simple approach, we successfully achieved enhanced cytosolic release of the CPPs and apoptosis induction using a pro-apoptotic domain with a very low peptide concentration (nM level) by light-induced condensation.

Size and surface modification of silica nanoparticles affect the severity of lung toxicity by modulating endosomal ROS generation in macrophages.

BACKGROUND: As the application of silica nanomaterials continues to expand, increasing chances of its exposure to the human body and potential harm are anticipated. Although the toxicity of silica nanomaterials is assumed to be affected by their physio-chemical properties, including size and surface functionalization, its molecular mechanisms remain unclear. We hypothesized that analysis of intracellular localization of the particles and subsequent intracellular signaling could reveal a novel determinant of inflammatory response against silica particles with different physico-chemical properties. RESULTS: We employed a murine intratracheal instillation model of amorphous silica nanoparticles (NPs) exposure to compare their in vivo toxicities in the respiratory system. Pristine silica-NPs of 50 nm diameters (50 nm-plain) induced airway-centered lung injury with marked neutrophilic infiltration. By contrast, instillation of pristine silica particles of a larger diameter (3 µm; 3 µm-plain) significantly reduced the severity of lung injury and neutrophilic infiltration, possibly through attenuated induction of neutrophil chemotactic chemokines including MIP2. Ex vivo analysis of alveolar macrophages as well as in vitro assessment using RAW264.7 cells revealed a remarkably lower cellular uptake of 3 µm-plain particles compared with 50 nm-plain, which is assumed to be the underlying mechanism of attenuated immune response. The severity of lung injury and neutrophilic infiltration was also significantly reduced after intratracheal instillation of silica NPs with an amine surface modification (50 nm-NH2) when compared with 50 nm-plain. Despite unchanged efficacy in cellular uptake, treatment with 50 nm-NH2 induced a significantly attenuated immune response in RAW264.7 cells. Assessment of intracellular redox signaling revealed increased reactive oxygen species (ROS) in endosomal compartments of RAW264.7 cells treated with 50 nm-plain when compared with vehicle-treated control. In contrast, augmentation of endosomal ROS signals in cells treated with 50 nm-NH2 was significantly lower. Moreover, selective inhibition of NADPH oxidase 2 (NOX2) was sufficient to inhibit endosomal ROS bursts and induction of chemokine expressions in cells treated with silica NPs, suggesting the central role of endosomal ROS generated by NOX2 in the regulation of the inflammatory response in macrophages that endocytosed silica NPs. CONCLUSIONS: Our murine model suggested that the pulmonary toxicity of silica NPs depended on their physico-chemical properties through distinct mechanisms. Cellular uptake of larger particles by macrophages decreased, while surface amine modification modulated endosomal ROS signaling via NOX2, both of which are assumed to be involved in mitigating immune response in macrophages and resulting lung injury.

Carbon nanotube/polymer composite coated tapered fiber for four wave mixing based wavelength conversion.

In this paper, we demonstrate a nonlinear optical device based on a fiber taper coated with a carbon nanotube (CNT)/polymer composite. Using this device, four wave mixing (FWM) based wavelength conversion of 10 Gb/s Non-return-to-zero signal is achieved. In addition, we investigate wavelength tuning, two photon absorption and estimate the effective nonlinear coefficient of the CNTs embedded in the tapered fiber to be 1816.8 W(-1)km(-1).

Ultrafast sensitivity-controlled and specific detection of extracellular vesicles using optical force with antibody-modified microparticles in a microflow system.

Extracellular vesicles (EVs), including nanoscale exosomes and ectosomes, hold promise as biomarkers that provide information about the cell of origin through their cargo of nucleic acids and proteins, both on their surface and within. Here, we develop a detection method of EVs based on light-induced acceleration of specific binding between their surface and antibody-modified microparticles, using a controlled microflow with three-dimensional analysis by confocal microscopy. Our method successfully detected 103-104 nanoscale EVs in liquid samples as small as a 500 nanoliters within 5 minutes, with the ability to distinguish multiple membrane proteins. Remarkably, we achieved the specific detection of EVs secreted from living cancer cell lines with high linearity, without the need for a time-consuming ultracentrifugation process that can take several hours. Furthermore, the detection range can be controlled by adjusting the action range of optical force using a defocused laser, consistent with the theoretical calculations. These findings demonstrate an ultrafast, sensitive, and quantitative approach for measuring biological nanoparticles, enabling innovative analyses of cell-to-cell communication and early diagnosis of various diseases, including cancer.

Inkjet-Based Intracellular Delivery System that Effectively Utilizes Cell-Penetrating Peptides for Cytosolic Introduction of Biomacromolecules through the Cell Membrane.

In the drug delivery system, the cytosolic delivery of biofunctional molecules such as enzymes and genes must achieve sophisticated activities in cells, and microinjection and electroporation systems are typically used as experimental techniques. These methods are highly reliable, and they have high intracellular transduction efficacy. However, a high degree of proficiency is necessary, and induced cytotoxicity is considered as a technical problem. In this research, a new intracellular introduction technology was developed through the cell membrane using an inkjet device and cell-penetrating peptides (CPPs). Using the inkjet system, the droplet volume, droplet velocity, and dropping position can be accurately controlled, and minute samples (up to 30 pL/shot) can be carried out by direct administration. In addition, CPPs, which have excellent cell membrane penetration functions, can deliver high-molecular-weight drugs and nanoparticles that are difficult to penetrate through the cell membrane. By using the inkjet system, the CPPs with biofunctional cargo, including peptides, proteins such as antibodies, and exosomes, could be accurately delivered to cells, and efficient cytosolic transduction was confirmed.

Environmental pH stress influences cellular secretion and uptake of extracellular vesicles.

Exosomes (extracellular vesicles/EVs) participate in cell-cell communication and contain bioactive molecules, such as microRNAs. However, the detailed characteristics of secreted EVs produced by cells grown under low pH conditions are still unknown. Here, we report that low pH in the cell culture medium significantly affected the secretion of EVs with increased protein content and zeta potential. The intracellular expression level and location of stably expressed GFP-fused CD63 (an EV tetraspanin) in HeLa cells were also significantly affected by environmental pH. In addition, increased cellular uptake of EVs was observed. Moreover, the uptake rate was influenced by the presence of serum in the cell culture medium. Our findings contribute to our understanding of the effect of environmental conditions on EV-based cell-cell communication.