Slug down-regulation by RNA interference inhibits invasion growth in human esophageal squamous cell carcinoma

<p>Abstract</p> <p>Background</p> <p>Esophageal squamous cell carcinoma (ESCC) is one of the most aggressive carcinomas of the gastrointestinal tract. We assessed the relevance of Slug in measuring the invasive potential of ESCC cells <it>in vitro </it>and <it>in vivo </it>in immunodeficient mice.</p> <p>Methods</p> <p>We utilized RNA interference to knockdown Slug gene expression, and effects on survival and invasive carcinoma were evaluated using a Boyden chamber transwell assay <it>in vitro</it>. We evaluated the effect of Slug siRNA-transfection and Slug cDNA-transfection on E-cadherin and Bcl-2 expression in ESCC cells. A pseudometastatic model of ESCC in immunodeficient mice was used to assess the effects of Slug siRNA transfection on tumor metastasis development.</p> <p>Results</p> <p>The EC109 cell line was transfected with Slug-siRNA to knockdown Slug expression. The TE13 cell line was transfected with Slug-cDNA to increase Slug expression. EC109 and TE13 cell lines were tested for the expression of apoptosis-related genes bcl-2 and metastasis-related gene E-cadherin identified previously as Slug targets. Bcl-2 expression was increased and E-cadherin was decreased in Slug siRNA-transfected EC109 cells. Bcl-2 expression was increased and E-cadherin was decreased in Slug cDNA-transfected TE13 cells. Invasion of Slug siRNA-transfected EC109 cells was reduced and apoptosis was increased whereas invasion was greater in Slug cDNA-transfected cells. Animals injected with Slug siRNA-transfected EC109 cells exhihited fewer seeded nodes and demonstrated more apoptosis.</p> <p>Conclusions</p> <p>Slug down-regulation promotes cell apoptosis and decreases invasion capability <it>in vitro </it>and <it>in vivo</it>. Slug inhibition may represent a novel strategy for treatment of metastatic ESCC.</p

Slug enhances invasion ability of pancreatic cancer cells through upregulation of matrix metalloproteinase-9 and actin cytoskeleton remodeling

Slug, a member of the Snail family of transcription factors, has a crucial role in the regulation of epithelial-mesenchymal transition (EMT) by suppressing several epithelial markers and adhesion molecules, including E-cadherin. A recent study demonstrated that no relationship exists between Slug and E-cadherin in pancreatic cancer. Another study showed that in malignant mesothelioma effusions Slug was associated with matrix metalloproteinase (MMP) expression, but that there was no association with E-cadherin. F-ascin is an actin-bundling protein involved in filopodia assembly and cancer invasion and metastasis of multiple epithelial cancer types. In this study, we investigated Slug, E-cadherin, and MMP-9 expression using immunohistochemistry in 60 patients with pancreatic cancer and their correlation with carcinoma invasion and metastasis. Additionally, we observed the effects of Slug on invasion and metastasis in the pancreatic cancer cell line PANC-1. Alterations in Slug, MMP-9, and E-cadherin were determined by RT-PCR, western blot, and immunohistochemistry. Alterations in MMP-9 and F-actin cytoskeleton were determined by immunofluorescence staining, flow cytometry (FCM), or gelatin zymography. Slug, E-cadherin, and MMP-9 expression in pancreatic cancer was significantly associated with lymph node metastases and we found a significant correlation between Slug and MMP-9 expression; however, no significant correlation was observed between Slug and E-cadherin expression. Slug transfection significantly increased invasion and metastasis in PANC-1 cells and orthotopic tumor of mouse in vivo, and significantly upregulated and activated MMP-9; however, there was no effect on E-cadherin expression. Slug promoted the formation of lamelliopodia or filopodia in PANC-1 cells. The intracellular F-actin and MMP-9 was increased and relocated to the front of the extending pseudopodia from the perinuclear pool in Slug-transfected PANC-1 cells. These results suggest that Slug promotes migration and invasion of PANC-1 cells, which may correlate with the reorganization of MMP-9 and remodeling of the F-actin cytoskeleton, but not with E-cadherin expression

Efficient hydrolytic hydrogen evolution from sodium borohydride catalyzed by polymer immobilized ionic liquid‐stabilized platinum nanoparticles

Platinum nanoparticles stabilized by imidazolium‐based phosphine‐decorated Polymer Immobilized Ionic Liquids (PPh2‐PIIL) catalyze the hydrolytic evolution of hydrogen from sodium borohydride with remarkable efficiency, under mild conditions. The composition of the polymer influences efficiency with the catalyst based on a polyethylene glycol modified imidazolium monomer (PtNP@PPh2‐PEGPIILS) more active than its N‐alkylated counterpart (PtNP@PPh2‐N‐decylPIILS). The maximum initial TOF of 169 moleH2.molcat−1.min−1 obtained at 30 °C with a catalyst loading of 0.08 mol% is among the highest to be reported for the aqueous phase hydrolysis of sodium borohydride catalyzed by a PtNP‐based system. Kinetic studies revealed that the apparent activation energy (Ea) of 23.9 kJ mol−1 for the hydrolysis of NaBH4 catalyzed by PtNP@PPh2‐PEGPIILS is significantly lower than that of 35.6 kJ mol−1 for PtNP@PPh2‐N‐decylPIILS. Primary kinetic isotope effects kH/kD of 1.8 and 2.1 obtained with PtNP@PPh2‐PEGPIILS and PtNP@PPh2‐N‐decylPIILS, respectively, for the hydrolysis with D2O support a mechanism involving rate determining oxidative addition or σ‐bond metathesis of the O−H bond. Catalyst stability and reuse studies showed that PtNP@PPh2‐PEGPIILS retained 70 % of its activity across five runs; the gradual drop in conversion appears to be due to poisoning of the catalyst by the accumulated metaborate product as well as the increased viscosity of the reaction mixture

An exact measurement of nucleation incubation times in isothermal crystallizations of liquid metal Al via configuration heredity

Nucleation induction time z* is a crucial parameter in the classical nucleation theory, which is intimately associated with the steady-state nucleation rate I0 in the homogenous nucleation. To examine the impact of temperatures T on z*(T) in the isothermal crystallizations of liquid metal Al, a series of molecular dynamics simulations are performed at different undercoolings Delta Tm. With the help of cluster type index method based on Honeycutt-Anderson bond-type index, a cluster analysis method based on the continuous heredity of crystal clusters is developed to further distinguish nuclei from various embryos. By means of the transient heredity of crystal clusters, a nucleation incubation time zc different from nucleation induction time, i.e., a sum of incubation time of embryo ze and its effective growth time zefg f prior to arriving the critical size, is introduced and exactly measured. For the critical nuclei emerged in the transient nucleation stage, the zc are found to be long compared with the steady-state nucleation stage and mainly depend on an effective growth of incubated embryos, while those in steady-state nucleation stage are mostly decided by a successful incubation of initial embryos. Also, relative to the z*(T) derived from I0(T) at different Delta Tm, these measured zc(T) are very small, but their average times zc(T) in the whole region are mirror symmetric to I0(T)

Radical tessellation of the packing of ternary mixtures of spheres

The packing of ternary mixtures of spheres with size ratios 24.4/11.6/6.4 is simulated by means of the discrete element method. The packing structure is analyzed by the so called radical tessellation which is an extension of the well-established Voronoi tessellation. The topological and metric properties of radical polyhedra are quantified as a function of the volume fractions of this ternary packing system. These properties include the number of edges, area and perimeter per radical polyhedron face, and the number of faces, surface area and volume per radical polyhedron. The properties of each component of a mixture are shown to be strongly dependent on the volume fractions. Their average values can be quantified by a cubic polynomial equation. The results should be useful for understanding the packing structures of multi-sized particles

Radical tessellation of the packing of spheres with a log-normal size distribution

The packing of particles with a log-normal size distribution is studied by means of the discrete element method. The packing structures are analyzed in terms of the topological properties such as the number of faces per radical polyhedron and the number of edges per face, and the metric properties such as the perimeter and area per face and the perimeter, area, and volume per radical polyhedron, obtained from the radical tessellation. The effect of the geometric standard deviation in the log-normal distribution on these properties is quantified. It is shown that when the size distribution gets wider, the packing becomes denser; thus the radical tessellation of a particle has decreased topological and metric properties. The quantitative relationships obtained should be useful in the modeling and analysis of structural properties such as effective thermal conductivity and permeability

Coordination number of the packing of ternary mixtures of spheres : DEM simulations versus measurements

Coordination number is an important microscopic parameter in describing the packing of particles. However, little information is available for particle mixtures because of the difficulty of investigating them experimentally. This article presents a numerical study on the coordination numbers of a ternary packing system with size ratios of 24.4/11.6/6.4 by means of the discrete element method (DEM). Good agreement between the simulated and measured results was obtained, which confirms, at a particle scale, that DEM is capable of generating reliable results for structural analysis of particle packing. It was also found that the coordination number distribution of each of the cases considered can be described by the so-called Johnson SB function. The distribution parameters of the function were quantified based on the DEM simulation results so that the coordination number distributions corresponding to different contact types in this ternary packing system can be fully described

An assessment of the mathematical models for estimating the coordination number of the packing of multisized particles

Coordination number (CN) is an important microscopic parameter in describing the packing of particles. There are a few mathematical models proposed in the literature to calculate the CN of a particle mixture. However, they have not been comprehensively assessed as the experimental data are limited. In this paper, the applicability of three models, respectively proposed by Dodds, Ouchiyama & Tanaka, and Suzuki & Oshima, is assessed against the results recently generated by means of discrete element method. The results indicate that the model of Ouchiyama & Tanaka differ from the simulated CNs significantly, thus not recommended. The other two models produce similar results, but the Dodds model is probably more reasonable. In particular, these two models are able to estimate the variation trend of the average CN for various particle size distributions but their predictability reduces with the increase of particle size difference. The Dodds model becomes numerically unsolvable when the small-to-large size ratio is smaller than 0.154. Therefore, modification of the existing models or development of a new model is required in future studies for better prediction of the CN of the packings of multisized particles