Fluidity of Poly (ε-Caprolactone)-Based Material Induces Epithelial-to-Mesenchymal Transition.

BACKGROUND: We propose the potential studies on material fluidity to induce epithelial to mesenchymal transition (EMT) in MCF-7 cells. In this study, we examined for the first time the effect of material fluidity on EMT using poly(ε-caprolactone-co-D,L-lactide) (P(CL-co-DLLA)) with tunable elasticity and fluidity. METHODS: The fluidity was altered by chemically crosslinking the polymer networks. The crosslinked P(CL-co-DLLA) substrate showed a solid-like property with a stiffness of 261 kPa, while the non-crosslinked P(CL-co-DLLA) substrate of 100 units (high fluidity) and 500 units (low fluidity) existed in a quasi-liquid state with loss modulus of 33 kPa and 30.8 kPa, respectively, and storage modulus of 10.8 kPa and 20.1 kPa, respectively. RESULTS: We observed that MCF-7 cells on low fluidic substrates decreased the expression of E-cadherin, an epithelial marker, and increased expression of vimentin, a mesenchymal marker. This showed that the cells lose their epithelial phenotype and gain a mesenchymal property. On the other hand, MCF-7 cells on high fluidic substrates maintained their epithelial phenotype, suggesting that the cells did not undergo EMT. CONCLUSION: Considering these results as the fundamental information for material fluidity induced EMT, our system could be used to regulate the degree of EMT by turning the fluidity of the material.

Material-induced Senescence (MIS): Fluidity Induces Senescent Type Cell Death of Lung Cancer Cells via Insulin-Like Growth Factor Binding Protein 5.

Objective: We propose here material-induced senescence (MIS) as a new therapeutic concept that limits cancer progression by stable cell cycle arrest. This study examined for the first time the effect of material fluidity on cellular senescence in lung carcinoma using poly(ε-caprolactone-co-D, L-lactide) (P(CL-co-DLLA)) with tunable elasticity and fluidity. Methods: The fluidity was varied by chemically crosslinking the polymer networks: the crosslinked P(CL-co-DLLA) shows solid-like properties with a stiffness of 260 kPa, while the non-crosslinked polymer exists in a quasi-liquid state with loss and storage moduli of 33 kPa and 11 kPa, respectively. Results: We found that cancer cells growing on the non-crosslinked, fluidic substrate undergo a non-apoptotic form of cell death and the cell cycle was accumulated in a G0/G1 phase. Next, we investigated the expression of biomarkers that are associated with cancer pathways. The cancer cells on the fluidic substrate expressed several biomarkers associated with senescence such as insulin-like growth factor binding protein 5 (IGFBP5). This result indicates that when cancer cells sense fluidity in their surroundings, the cells express IGFBP5, which in turn triggers the expression of tumor suppressor protein 53 and initiates cell cycle arrest at the G1 phase followed by cellular senescence. Furthermore, the cancer cells on the fluidic substrate maintained their epithelial phenotype, suggesting that the cancer cells do not undergo epithelial to mesenchymal transition. Conclusion: By considering these results as the fundamental information for MIS, our system could be applied to induce senescence in treatment-resistant cancers such as metastatic cancer or cancer stem cells.

Comparison of cellular uptake and inflammatory response via toll-like receptor 4 to lipopolysaccharide and titanium dioxide nanoparticles.

The innate immune response is the earliest cellular response to infectious agents and mediates the interactions between microbes and cells. Toll-like receptors (TLRs) play an important role in these interactions. We have already shown that TLRs are involved with the uptake of titanium dioxide nanoparticles (TiO2 NPs) and promote inflammatory responses. In this paper, we compared role of cellular uptake and inflammatory response via TLR 4 to lipopolysaccharide (LPS) and TiO2 NPs. In the case of LPS, LPS binds to LPS binding protein (LBP) and CD 14, and then this complex binds to TLR 4. In the case of TiO2 NPs, the necessity of LBP and CD 14 to induce the inflammatory response and for uptake by cells was investigated using over-expression, antibody blocking, and siRNA knockdown experiments. Our results suggested that for cellular uptake of TiO2 NPs, TLR 4 did not form a complex with LBP and CD 14. In the TiO2 NP-mediated inflammatory response, TLR 4 acted as the signaling receptor without protein complex of LPS, LBP and CD 14. The results suggested that character of TiO2 NPs might be similar to the complex of LPS, LBP and CD 14. These results are important for development of safer nanomaterials.

Effect of polyethylene glycol modification of TiO2nanoparticles on cytotoxicity and gene expressions in human cell lines.

Nanoparticles (NPs) are tiny materials used in a wide range of industrial and medical applications. Titanium dioxide (TiO(2)) is a type of nanoparticle that is widely used in paints, pigments, and cosmetics; however, little is known about the impact of TiO(2) on human health and the environment. Therefore, considerable research has focused on characterizing the potential toxicity of nanoparticles such as TiO(2) and on understanding the mechanism of TiO(2) NP-induced nanotoxicity through the evaluation of biomarkers. Uncoated TiO(2) NPs tend to aggregate in aqueous media, and these aggregates decrease cell viability and induce expression of stress-related genes, such as those encoding interleukin-6 (IL-6) and heat shock protein 70B' (HSP70B'), indicating that TiO(2) NPs induce inflammatory and heat shock responses. In order to reduce their toxicity, we conjugated TiO(2) NPs with polyethylene glycol (PEG) to eliminate aggregation. Our findings indicate that modifying TiO(2) NPs with PEG reduces their cytotoxicity and reduces the induction of stress-related genes. Our results also suggest that TiO(2) NP-induced effects on cytotoxicity and gene expression vary depending upon the cell type and surface modification.