Small cell lung cancer,an epithelial to mesenchymal transition (EMT)-like cancer: significance of inactive Notch signaling and expression of achaete-scute complex homologue 1

Small cell lung cancer (SCLC) is one of the most malignant neoplasms in common human cancers. The tumor is composed of small immature-looking cells with a round or fusiform shape, which possesses weak adhesion features among them, suggesting that SCLC shows the morphological characteristics of epithelial to mesenchymal transition (EMT). SCLC is characterized by high metastatic and recurrent rates, sensitivity to the initial chemotherapy, and easy acquirement of chemoresistance afterwards. These characters may be related to the EMT phenotype of SCLC. Notch signaling is an important signaling pathway, and could have roles in regulating neuroendocrine differentiation, proliferation, cell adhesion, EMT, and chemoresistance. Notch1 is usually absent in SCLC in vivo, but could appear after chemotherapy. Notch1 can enhance cell adhesion by induction of E-cadherin in SCLC, which indicates mesenchymal to epithelial transition. On the other hand, achaete-scute complex homologue 1 (ASCL1), negatively regulated by Notch signaling, is a lineage-specific gene of SCLC, and functions to promote neuroendocrine differentiation as well as EMT. ASCL1-transfected adenocarcinoma cell lines induced neuroendocrine phenotypes and lost epithelial cell features. SCLC is characterized by neuroendocrine differentiation and EMT-like features, which could be produced by inactive Notch signaling and ASCL1 expression. In addition, chemical and radiation treatments can activate Notch signaling, which suppress neuroendocrine differentiation and induces chemoradioresistance, accompanied by secession from EMT. Thus, the status of Notch signaling and ASCL1 expression may determine the cell behaviors of SCLC partly through modifying EMT phenotypes.     

Reduction in DHA transport to the brain of mice expressing human APOE4 compared to APOE2

Benefits on cognition from docosahexaenoic acid (DHA, 22 : 6 n‐3) intake are absent in humans carrying apolipoprotein E ε4 allele (APOE4), the most important genetic risk factor for Alzheimer's disease (AD). To test the hypothesis that carrying APOE4 impairs DHA distribution, we evaluated plasma and brain fatty acid profiles and uptake of [¹⁴C]‐DHA using in situ cerebral perfusion through the blood–brain barrier in 4‐ and 13‐month‐old male and female APOE‐targeted replacement mice (APOE2, APOE3, and APOE4), fed with a DHA‐depleted diet. Cortical and plasma DHA were 9% lower and 34% higher in APOE4 compared to APOE2 mice, respectively. Brain uptake of [¹⁴C]‐DHA was 24% lower in APOE4 versus APOE2 mice. A significant relationship was established between DHA and apoE concentrations in the cortex of mice (r² = 0.21) and AD patients (r² = 0.32). Altogether, our results suggest that lower brain uptake of DHA in APOE4 than in APOE2 mice may limit the accumulation of DHA in cerebral tissues. These data provide a mechanistic explanation for the lack of benefit of DHA in APOE4 carriers on cognitive function and the risk of AD.

     

Synthesis of new polymer-bound adenine nucleotides using starburst PAMAM dendrimers

Two types of new polymer-bound adenine nucleotides were synthesized by coupling adenine nucleotides (ATP and ADP) with starburst polyamidoamine (PAMAM) dendrimers. The first type was obtained by coupling native adenine nucleotides directly with a carboxy-terminated PAMAM dendrimer. In the second type, the nucleotides were modified by introducing a spacer arm containing a carboxylic end group (N(6)-R-ATP and N(6)-R-ADP) and coupled with an amine-terminated PAMAM dendrimer. Both types of the dendrimers were coupled with native or the modified nucleotides using the well-known carbodiimide activation technique. The optimum coupling pH and temperature were 4 and 30 degrees C, respectively, for preparing the carboxy-terminated PAMAM-bound ATP or ADP, and were 9 and 50 degrees C, respectively, for preparing the amine-terminated PAMAM-bound N(6)-R-ATP or N(6)-R-ADP. The ATP or ADP contents in the synthesized polymers were found to be 4 mol of ATP or of ADP/mol of carboxy-terminated PAMAM-bound ATP or ADP and 25 mol of ATP or of ADP/mol of amine-terminated PAMAM-bound N(6)-R-ATP or N(6)-R-ADP. The coenzymatic activities relative to the native ATP of the carboxy-terminated PAMAM-bound ATP against glucokinase and hexokinase were 16 and 7%, respectively, and those of the amine-terminated PAMAM-bound N(6)-R-ATP 2 and 1%, respectively. The coenzymatic activities relative to the native ADP of the carboxy-terminated PAMAM-bound ADP and the amine-terminated PAMAM-bound N(6)-R-ADP against acetate kinase were 24 and 3.5%, respectively.     

Synthesis and Anti-Proliferative Activity of New Acridinyl and Benzothiazolyl-Based Triazole Glycosides via Click Cycloaddition and Their Tetrazolyl Analogs

Russian Journal of Bioorganic Chemistry - Novel acridine and benzothiazole substituted 1,2,3-triazole glycosides were synthesized by using Cu(I)-Catalyzed Azide-Alkyne Cycloaddition (CAAC) known as...     

HDAC1 inhibition by maspin abrogates epigenetic silencing of glutathione S-transferase pi in prostate carcinoma cells

Both maspin and glutathione S-transferase pi (GSTp) are implicated as tumor suppressors and downregulated in human prostate cancer. It is well established that GSTp downregulation is through DNA methylation-based silencing. We report here that maspin expression in prostate cancer cell line DU145 reversed GSTp DNA methylation, as measured by methylation- specific PCR, MethyLight assay, and bisulfite sequencing. The effect of maspin on GSTp expression was similar to that of the combination of a synthetic histone deacetylase (HDAC) inhibitor and DNA methylation inhibitor 5-aza-2'-deoxycytidine. Maspin expression also led to an increased level of acetylated histone 3, decreased level of methyl transferase, and methyl-CpG-binding domain proteins at the site of demethylated GSTp promoter DNA. Earlier, we have shown that maspin inhibits HDAC1. In PC3 cells, where both maspin and GSTp are expressed at a reduced level, maspin knockdown led to a significant reduction in GSTp expression, whereas dual knockdown of maspin and HDAC1 barely increased the level of GSTp expression. Thus, HDAC1 may play an essential role in cellular response to maspin-mediated GSTp desilencing. Maspin has been shown to increase tumor cell sensitivity to drug-induced apoptosis. Interestingly, GSTp reexpression in the absence of maspin expression perturbation blocked the phosphorylation of histone 2A.X, the induction of hypoxia-induced factor 1α (HIF-1α), and cell death of LNCaP cells under oxidative stress. Because DNA hypermethylation-based silencing may couple with and depend on histone deacetylation, our study suggests that endogenous HDAC inhibition by maspin may prevent pathologic gene silencing in prostate tumor progression.     

The Relationship Between Menopause and Metabolic Syndrome: Experimental and Bioinformatics Analysis

Biochemical Genetics - Menopausal hormonal changes have been associated with the emergence of the metabolic syndrome (MetS) and its consequences such as type 2 diabetes (T2D) and cardiovascular...     

Wheat germ in?vitro translation to produce one of the most toxic sodium channel specific toxins

Envenoming following scorpion sting is a common emergency in many parts of the world. During scorpion envenoming, highly toxic small polypeptides of the venom diffuse rapidly within the victim causing serious medical problems. The exploration of toxin structure-function relationship would benefit from the generation of soluble recombinant scorpion toxins in Escherichia coli. We developed an in vitro wheat germ translation system for the expression of the highly toxic Aah (Androctonus australis hector)II protein that requires the proper formation of four disulphide bonds. Soluble, recombinant N-terminal GST (glutathione S-transferase)-tagged AahII toxin is obtained in this in vitro translation system. After proteolytic removal of the GST-tag, purified rAahII (recombinant AahII) toxin, which contains two extra amino acids at its N terminal relative to the native AahII, is highly toxic after i.c.v. (intracerebroventricular) injection in Swiss mice. An LD₅₀ (median lethal dose)-value of 10 ng (or 1.33 pmol), close to that of the native toxin (LD₅₀ of 3 ng) indicates that the wheat germ in vitro translation system produces properly folded and biological active rAahII. In addition, NbAahII10 (Androctonus australis hector nanobody 10), a camel single domain antibody fragment, raised against the native AahII toxin, recognizes its cognate conformational epitope on the recombinant toxin and neutralizes the toxicity of purified rAahII upon injection in mice.