Adenovirus adenine nucleotide translocator-2 shRNA effectively induces apoptosis and enhances chemosensitivity by the down-regulation of ABCG2 in breast cancer stem-like cells

Cancer stem cells (CSCs) are resistant to chemo- and radio-therapy, and can survive to regenerate new tumors. This is an important reason why various anti- cancer therapies often fail to completely control tumors, although they kill and eliminate the bulk of cancer cells. In this study, we determined whether or not adenine nucleotide translocator-2 (ANT2) suppression could also be effective in inducing cell death of breast cancer stem-like cells. A sub-population (SP; CD44+/ CD24-) of breast cancer cells has been reported to have stem/progenitor cell properties. We utilized the adeno- ANT2 shRNA virus to inhibit ANT2 expression and then observed the treatment effect in a SP of breast cancer cell line. In this study, MCF7, MDA-MB-231 cells, and breast epithelial cells (MCF10A) mesenchymally-transdifferentiated through E-cadherin knockdown were used. ANT2 expression was high in both stem-like cells and non-stem-like cells of MCF7 and MDA-MB-231 cells, and was induced and up-regulated by mesenchymal transdifferentiation in MCF10A cells (MCF10A(EMT)). Knockdown of ANT2 by adeno-shRNA virus efficiently induced apoptotic cell death in the stem-like cells of MCF7 and MDA-MB-231 cells, and MCF10A(EMT). Stem-like cells of MCF7 and MDA-MB-231, and MCF10A(EMT) cells exhibited increased drug (doxorubicin) resistance, and expressed a multi-drug resistant related molecule, ABCG2, at a high level. Adeno-ANT2 shRNA virus markedly sensitized the stem-like cells of MCF7 and MDA-MB-231, and the MCF10A(EMT) cells to doxorubicin, which was accompanied by down-regulation of ABCG2. Our results suggest that ANT2 suppression by adeno-shRNA virus is an effective strategy to induce cell death and increase the chemosensitivity of stem-like cells in breast cancer.     

Structure‐Directing Agents for the Synthesis of TiO2‐Based Drug‐Delivery Systems

A series of titanium oxides was prepared by using a surfactant‐template method (STM) and used as a carrier for the sustained release of ibuprofen, which was chosen as a model drug. This STM provides an efficient route to TiO₂ matrices with both high surface area (when compared with those that were obtained by using traditional synthetic approaches) and well‐defined mesoporous textures. Some parameters of the synthetic procedure were varied: pH value, surfactant, and thermal treatment. The physicochemical nature of the surface carriers were investigated by means of N₂‐physisorption measurements and FTIR spectroscopy. The effect of the amount of drug on the release kinetics was also investigated. The drug delivery was evaluated in vitro in four different physiological solutions (that simulated the gastrointestinal tract) to analyze the behavior of the TiO₂‐based systems if they were to be formulated as oral DDSs. Our optimized approach is a good alternative to the classical methods that are used to prepare efficient TiO₂‐based drug‐delivery systems.     

Poly(acrylic acid)‐Modified Fe3O4 Microspheres for Magnetic‐Targeted and pH‐Triggered Anticancer Drug Delivery

Monodisperse poly(acrylic acid)‐modified Fe₃O₄ (PAA@Fe₃O₄) hybrid microspheres with dual responses (magnetic field and pH) were successfully fabricated. The PAA polymer was encapsulated into the inner cavity of Fe₃O₄ hollow spheres by a vacuum‐casting route and photo‐initiated polymerization. TEM images show that the samples consist of monodisperse porous spheres with a diameter around 200 nm. The Fe₃O₄ spheres, after modification with the PAA polymer, still possess enough space to hold guest molecules. We selected doxorubicin (DOX) as a model drug to investigate the drug loading and release behavior of as‐prepared composites. The release of DOX molecules was strongly dependent on the pH value due to the unique property of PAA. The HeLa cell‐uptake process of DOX‐loaded PAA@Fe₃O₄ was observed by confocal laser scanning microscopy (CLSM). After being incubated with HeLa cells under magnet magnetically guided conditions, the cytotoxtic effects of DOX‐loaded PAA@Fe₃O₄ increased. These results indicate that pH‐responsive magnetic PAA@Fe₃O₄ spheres have the potential to be used as anticancer drug carriers.     

Mathematical Modeling of Drug Release in a Phase-Transient Temperature-Responsive Drug Delivery System in Spherical Coordinates

Abstract

A sphere-shaped drug delivery system responsive to temperature, as a unique external stimulus, was introduced and its performance mathematically studied at the pseudo-steady state. The system is composed of three individual sections, including the drug core, phase-transient intermediate shell, and protective polymeric shell. An ON-OFF release of drug could be achieved by increasing or decreasing the environmental temperature around the melting point of the intermediate shell and the smartness of system is due to the solid-liquid phase transition of this shell. The ON-OFF response of the system was mathematically modeled by solving the governing heat and mass transfer equations at the pseudo-steady state. The results showed the lag time of the system in the ON state, the cumulative released drug in the ON state and the fractional undesired release of drug in the OFF state are strongly under the influences of different kinds of factors, including the geometrical characteristics of the system (e.g., the radius of the drug core and the thicknesses of the intermediate and polymeric shells), the physical properties of the system (e.g., the thermal conductivities and diffusion coefficients of the intermediate and polymeric shells), and the environmental and operation conditions.     

Simultaneous Determination of Five Nonsteroidal Anti-Inflammatory Drugs and Two Glucocorticoids in Adulterated Traditional Herbal Medicines for the Treatment of Rheumatism

The adulteration of traditional herbal medicines (THMs) with synthetic drugs is prevalent and represents a serious risk for public health. A rapid and novel reversed-phase high-performance liquid chromatography (HPLC) method was established and validated for the simultaneous determination of five nonsteroidal anti-inflammatory drugs (NSAIDs) and two glucocorticoids in THMs for rheumatoid treatment. Glipizide was used as the internal standard (IS). The separation was completed on a C₁₈ column with a mobile phase consisting of methanol and a buffer solution containing 10 mM ammonium acetate and 0.1% formic acid with a gradient elution. All calibration curves showed good linear regression (r ² > 0.9996), and the recoveries of the seven analytes were in the range of 96.94%–105.37%. A liquid chromatography-mass spectrometry (LC-MS) method was developed to confirm the identity of the adulterants. The proposed method was applied to identify and determine the five NSAIDs and two glucocorticoids in THMs for rheumatism.     

An Enzyme Sensor For Determination of Acetylcholine and Choline In Rat Brain Extracts

Abstract

A choline enzyme sensor, recently developed by the authors, was used for choline and acetylcholine determination in rat brain extracts, using choline oxidase immobilized on cellulose triacetate membranes, and acetylcholinesterase in homogeneous solution. the method proved useful for assay of the acetylcholine content in a commercial pharmaceutical formulation used in ophthalmology.     

Quantum mechanically derived AMBER-compatible heme parameters for various states of the cytochrome P450 catalytic cycle

Molecular mechanics (MM) methods are computationally affordable tools for screening chemical libraries of novel compounds for sites of P450 metabolism. One challenge for MM methods has been the absence of a consistent and transferable set of parameters for the heme within the P450 active site. Experimental data indicate that mammalian P450 enzymes vary greatly in the size, architecture, and plasticity of their active sites. Thus, obtaining X-ray-based geometries for the development of accurate MM parameters for the major classes of hepatic P450 remains a daunting task. Our previous work with preliminary gas-phase quantum mechanics (QM)-derived atomic partial charges greatly improved the accuracy of docking studies of raloxifene to CYP3A4. We have therefore developed and tested a consistent set of transferable MM parameters based on gas-phase QM calculations of two model systems of the heme-a truncated (T-HM) and a full (F-HM) for four states of the P450 catalytic cycle. Our results indicate that the use of the atomic partial charges from the F-HM further improves the accuracy of docked predictions for raloxifene to CYP3A4. Different patterns for substrate docking are also observed depending on the choice of heme model and state. Newly parameterized heme models are tested in implicit and explicitly solvated MD simulations in the absence and presence of enzyme structures, for CYP3A4, and appear to be stable on the nanosecond simulation timescale. The new force field for the various heme states may aid the community for simulations of P450 enzymes and other heme-containing enzymes.     

Molecular Nanoworm with PCL Core and PEO Shell as a Non‐spherical Carrier for Drug Delivery

Core/shell wormlike polymer brushes with densely grafted poly(ϵ‐caprolactone)‐b‐poly(ethylene oxide) (PCL‐b‐PEO) are synthesized via grafting an alkynyl terminated PCL‐b‐PEO (ay‐PCL₁₇‐b‐PEO₁₁₃) onto a well‐defined azido functionalized polymethacrylate (PGA₉₄₀) and are evaluated preliminarily as a single molecular cylindrical vehicle for drug delivery. Water soluble molecular worms of ca. 230 nm are obtained and then the anticancer drug doxorubicin (DOX) is loaded into its PCL core by hydrophobic interaction. Compared with spherical micelles from linear PCL₁₇‐b‐PEO₁₁₃, the brushes demonstrate a lower loading efficiency but a faster release rate of DOX. Confocal laser scanning microscopy measurements show that DOX‐loaded cylindrical molecular brushes can easily enter into HeLa and HepG2 cells in 1 h.     

Hierarchical Micro/Nanostructures of Natural Polymer for Release Process

In this paper the modeling of drug release process from hierarchical dispersed systems such as nano and microparticles prepared by thermal cross-linking of multiple emulsions is described. The presented model considers the diffusion of a drug through spherical eroding natural polymer matrix and diffusion-convection of the drug in the surrounding medium. Simulated release profiles were compared with experimental data of the drug release from microspheres of various structures. The differences in microspheres structure resulted from changes in mixing intensity of the external surrounding. The simulations of release profiles confirmed the importance of the internal structure of microspheres as well as an intensity of external mixing in the modeling of the controlled release process. The presented model allowed the mass of drug released to be determined with satisfactory agreement with experimental data after optimization of parameters describing internal microspheres structure. The proposed model describing release process of a drug from microspheres can be applied for simulation of release profiles with phasic behavior (primary/lag and continuous release). The model simulations were extended to drug release from nanoparticles with satisfactory results.     

Physicochemical characterization and drug release properties of PDMAEMA/OSA Semi‐IPN hydrogels with microporous structure

A new poly(2‐(dimethylamino) ethyl methacrylate)/oxidized sodium alginate (PDMAEMA) semi‐interpenetrating network (Semi‐IPN) hydrogel with microporous structure was prepared by using PDMAEMA microgels as an additive during the polymerization/crosslinking process. The interior morphology characterized by scanning electron microscopy showed the Semi‐IPN hydrogels have different pore sizes by changing the amount of microgels. The hydrogels were also characterized by using Fourier transform infrared and DSC. The swelling behaviors of hydrogels indicated that the hydrogels have excellent pH and temperature sensitivity. Bovine serum albumin was entrapped in the hydrogels and the in vitro drug release profiles were established in different buffer solutions at various temperatures. The release behaviors of the model drug were dependent on the pore size of the hydrogels and environmental temperature/pH, which suggested that these materials have potential application as intelligent drug carriers. Copyright © 2011 John Wiley & Sons, Ltd.