Chitosan and its derivatives as nanocarriers for siRNA delivery

The ability to specifically silence genes using siRNA has enormous potential for treating genetic diseases. However, siRNA instability and biodistribution issues still need to be overcome, and adequate delivery vehicles have proven indispensable in conveying siRNA to its target. Chitosan is a promising biopolymer for siRNA delivery, its interest stemming from its safety, biodegradability, mucoadhesivity, permeation enhancing effect and cationic charge, as well as amenability to undergo chemical modifications. Chitosan and its derivatives can be readily arranged into complexes or nanoparticles able to entrap and carry siRNA. Specific strategies have been adopted to improve chitosan-based vectors with regard to transfectability. However, further efforts are required to verify their value and adapt them to enhance therapeutic output prior to clinical application. This review emphasizes the potential of chitosan and its derivatives to develop nanocarriers for siRNA delivery. The properties of chitosan that are significant for transfectability and the most relevant findings are assessed

Integrated genomic characterization of oesophageal carcinoma

Oesophageal cancers are prominent worldwide; however, there are few targeted therapies and survival rates for these cancers remain dismal. Here we performed a comprehensive molecular analysis of 164 carcinomas of the oesophagus derived from Western and Eastern populations. Beyond known histopathological and epidemiologic distinctions, molecular features differentiated oesophageal squamous cell carcinomas from oesophageal adenocarcinomas. Oesophageal squamous cell carcinomas resembled squamous carcinomas of other organs more than they did oesophageal adenocarcinomas. Our analyses identified three molecular subclasses of oesophageal squamous cell carcinomas, but none showed evidence for an aetiological role of human papillomavirus. Squamous cell carcinomas showed frequent genomic amplifications of CCND1 and SOX2 and/or TP63, whereas ERBB2, VEGFA and GATA4 and GATA6 were more commonly amplified in adenocarcinomas. Oesophageal adenocarcinomas strongly resembled the chromosomally unstable variant of gastric adenocarcinoma, suggesting that these cancers could be considered a single disease entity. However, some molecular features, including DNA hypermethylation, occurred disproportionally in oesophageal adenocarcinomas. These data provide a framework to facilitate more rational categorization of these tumours and a foundation for new therapies

Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)

In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. For example, a key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process versus those that measure fl ux through the autophagy pathway (i.e., the complete process including the amount and rate of cargo sequestered and degraded). In particular, a block in macroautophagy that results in autophagosome accumulation must be differentiated from stimuli that increase autophagic activity, defi ned as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (inmost higher eukaryotes and some protists such as Dictyostelium ) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the fi eld understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. It is worth emphasizing here that lysosomal digestion is a stage of autophagy and evaluating its competence is a crucial part of the evaluation of autophagic flux, or complete autophagy. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. Along these lines, because of the potential for pleiotropic effects due to blocking autophagy through genetic manipulation it is imperative to delete or knock down more than one autophagy-related gene. In addition, some individual Atg proteins, or groups of proteins, are involved in other cellular pathways so not all Atg proteins can be used as a specific marker for an autophagic process. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field

The inhibitory effect of Gremlin-2 on adipogenesis suppresses breast cancer cell growth and metastasis

Abstract Background Gremlin-1 (GREM1) and Gremlin-2 (GREM2) are bone morphogenetic protein antagonists that play important roles in organogenesis, tissue differentiation, and tissue homeostasis. Although GREM1 has been reported to be involved in promoting various cancers, little has been reported about effects of GREM2 on cancer. Recently, it has been reported that GREM2 can inhibit adipogenesis in adipose-derived stromal/stem cells. However, as an inhibitor of adipogenesis, the role of GREM2 in cancer progression is not well understood yet. Methods Pre-adipocyte 3T3-L1 cells overexpressing mock or Grem2 were established using a lentiviral transduction system and differentiated into adipocytes-mock and adipocytes-Grem2, respectively. To investigate the effect of adipocyte-Grem2 on breast cancer cells, we analyzed the proliferative and invasion abilities of spheroids using a 3D co-culture system of breast cancer cells and adipocytes or conditioned medium (CM) of adipocytes. An orthotopic breast cancer mouse model was used to examine the role of adipocytes-Grem2 in breast cancer progression. Results Grem2 overexpression suppressed adipogenesis of 3T3-L1 cells. Proliferative and invasion abilities of spheroids formed by co-culturing MTV/TM-011 breast cancer cells and adipocytes-Grem2 were significantly reduced compared to those of spheroids formed by co-culturing MTV/TM-011 cells and adipocytes-mock. Compared to adipocytes-mock, adipocytes-Grem2 showed decreased mRNA expression of several adipokines, notably IL-6. The concentration of IL-6 in the CM of these cells was also decreased. Proliferative and invasive abilities of breast cancer cells reduced by adipocytes-Grem2 were restored by IL-6 treatment. Expression levels of vimentin, slug, and twist1 in breast cancer cells were decreased by treatment with CM of adipocytes-Grem2 but increased by IL-6 treatment. In orthotopic breast cancer mouse model, mice injected with both MTV/TM-011 cells and adipocytes-Grem2 showed smaller primary tumors and lower lung metastasis than controls. However, IL-6 administration increased both the size of primary tumor and the number of metastatic lung lesions, which were reduced by adipocytes-Grem2. Conclusions Our study suggests that GREM2 overexpression in adipocytes can inhibit adipogenesis, reduce the expression and secretion of several adipokines, including IL-6, and ultimately inhibit breast cancer progression

Differential Protective Effects of Exenatide, an Agonist of GLP-1 Receptor and Piragliatin, a Glucokinase Activator in Beta Cell Response to Streptozotocin-Induced and Endoplasmic Reticulum Stresses

<div><p>Background</p><p>Agonists of glucagon-like peptide-1 receptor (GLP-1R) and glucokinase activators (GKA) act as antidiabetic agents by their ability protect beta cells, and stimulate insulin secretion. Oxidative and endoplasmic reticulum (ER) stresses aggravate type 2 diabetes by causing beta cell loss. It was shown that GLP-1R agonists protect beta cells from oxidative and ER stresses. On the other hand, little is known regarding how GKAs protect beta cells. We hypothesized that GKAs protect beta cells by mechanisms distinct from those underlying GLP-1R agonist and tested our hypothesis by comparing the molecular effects of exenatide, a GLP-1R agonist, and piragliatin, a GKA, on INS-1 cells under oxidative and ER-induced stresses.</p><p>Methods</p><p>Beta cells were treated with streptozotocin (STZ) to induce oxidative stress and with palmitate or thapsigargin (Tg) to induce ER stress respectively, and the effects of exenatide and piragliatin on these cells were investigated by: a) characterizing the kinases involved employing specific kinase inhibitors, and b) by identifying the differentially regulated proteins in response to stresses with proteomic analysis.</p><p>Results</p><p>Exenatide protected INS-1 cells from both ER and STZ-induced death. In contrast, piragliatin rescued the cells only from STZ-induced stress. Akt activation by exenatide appeared to contribute to its protective effects of beta cells while enhanced glucose utilization was the contributing factor in the case of piragliatin. Also, exenatide, not piragliatin, blocked changes in proteins 14-3-3β, ε and θ, and preserved the 14-3-3θ levels under the ER stress. Isoform-specific modifications of 14-3-3, and the reduction of 14-3-3θ, commonly associated with beta cell death were assessed.</p><p>Conclusions</p><p>Exenatide and piragliatin exert distinct effects on beta cell survival and thus on type 2 diabetes. This study which confirmed our hypothesis is also the first to observe specific modulation of 14-3-3 isoform in stress-induced beta cell death associated with progressive deterioration of type 2 diabetes.</p></div

Identification of protein spots appearing in exenatide and piragliatin treated INS-1 cells by differential 2D analysis.

<p>Six hours after treatment with 0.3 µM Tg in the presence or absence of either 10 nM exenatide or 10 µM piragliatin, INS-1 cells were harvested and lysed for 2D analysis. After electrofocusing on strip gels (18 cm, pH 4–7), samples were separated on 10% acrylamide gels, silver stained, and scanned for image analysis (A). Representative images of six protein spots are shown in (B). (C) Each protein spot was cut out, destained and in-gel digested by trypsin. Digested samples were extracted, separated, and identified using nanoUPLC-ESI-q-TOF tandem MS.</p

Levels of protein 14-3-3θ negatively correlate with the viability of INS-1 cells.

<p>(A–C) Levels of protein 14-3-3 isoforms were assessed by immunoblotting at the end of treatment. (A) A representative image, (B) quantification data for Tg treatment and (C) for STZ treatment denoting mean ± S.E. from three different samples. Control, Tg or STZ alone, Tg or STZ plus 10 nM exenatide, and Tg or STZ plus 10 µM piragliatin; *, P<0.05 vs. each control by Bonferroni's post hoc analysis. (D–E) INS-1 cells were transfected with specific siRNA for 14-3-3θ, control scrambed siRNA, or without siRNA for 48 h. (D) Knockdown of 14-3-3θ was confirmed by immunoblotting anti-14-3-3θ antibody. *, P<0.05 by Student's t-test. (E) At the end of treatment in a same experiment, cellular viability was assessed by adding CCK-8 reagent (Dojindo Laboratories, Kumamoto, Japan) in supernatant and incubating cells for 1 h at 37°C followed by measuring optical density at 450 nm according to the manufacturer's instruction. Different alphabet characters indicate different statistical significance (P<0.05 by Bonferroni's post hoc analysis).</p

Identification of post-translationally produced potein 14-3-3 isoforms.

<p>(A) Appearances of three spots of 14-3-3 isoforms accorded with beta cell death regardless of the type of death stimulus. (B) After pretreatment of 10 µg/ml cycloheximide in INS-1 cells for 0.5 h, cells were treated with 0.3 µM Tg in the presence or absence of cylcloheximide and either 10 nM exenatide or 10 µM piragliatin. (C) In a separate experiment, cycloheximide-induced cytotoxicity was assessed by cellular ATP levels 6.5 h after cycloheximide treatment. (D) A representative image of related MS spectrum and identified modifications of 14-3-3β, ε, and θ. (E) After 20 µM JNK inhibitor was pretreated for 1 h and treated with 0.3 µM Tg, three spots of 14-3-3 proteins were determined on 2D gels.</p