Synthesis of AZT analogues: 7-(3-azido-2hydroxypropyl)-, 7-(3-amino-2-hydroxypropyl)-, 7-(3-triazolyl-2-hydroxypropyl)theophyllines

Nucleophilic displacement of the tosyloxy group in 7-(2-hydroxy-3-p-toluenesulfonyloxypropyl)theophylline (1) with azide anion afforded 7-(3-azido-2-hydroxypropyl)theophylline (2). Reduction of the 3-azido group in 2 with Ph₃P/Py/NH₄OH afforded the 3-amino derivative 4, alternatively obtained by regioselective amination of 7-(2,3-epoxypropyl)theophylline (3). Selective acetylation of 4 gave the N-acetyl derivative 5. 1,3-Dipolar cycloaddition of the azide group in 2 with N¹-propargyl thymine (6) afforded the regioisomeric triazole 7.     

Context dependent reversion of tumor phenotype by connexin-43 expression in MDA-MB231 cells and MCF-7 cells: Role of β-catenin/connexin43 association

Connexins (Cx), gap junction (GJ) proteins, are regarded as tumor suppressors, and Cx43 expression is often down regulated in breast tumors. We assessed the effect of Cx43 over-expression in 2D and 3D cultures of two breast adenocarcinoma cell lines: MCF-7 and MDA-MB-231. While Cx43 over-expression decreased proliferation of 2D and 3D cultures of MCF-7 by 56% and 80% respectively, MDA-MB-231 growth was not altered in 2D cultures, but exhibited 35% reduction in 3D cultures. C-terminus truncated Cx43 did not alter proliferation. Untransfected MCF-7 cells formed spherical aggregates in 3D cultures, and MDA-MB-231 cells formed stellar aggregates. However, MCF-7 cells over-expressing Cx43 formed smaller sized clusters and Cx43 expressing MDA-MB-231 cells lost their stellar morphology. Extravasation ability of both MCF-7 and MDA-MB-231 cells was reduced by 60% and 30% respectively. On the other hand, silencing Cx43 in MCF10A cells, nonneoplastic human mammary cell line, increased proliferation in both 2D and 3D cultures, and disrupted acinar morphology. Although Cx43 over-expression did not affect total levels of β-catenin, α-catenin and ZO-2, it decreased nuclear levels of β-catenin in 2D and 3D cultures of MCF-7 cells, and in 3D cultures of MDA-MB-231 cells. Cx43 associated at the membrane with α-catenin, β-catenin and ZO-2 in 2D and 3D cultures of MCF-7 cells, and only in 3D conditions in MDA-MB-231 cells. This study suggests that Cx43 exerts tumor suppressive effects in a context-dependent manner where GJ assembly with α-catenin, β-catenin and ZO-2 may be implicated in reducing growth rate, invasiveness, and, malignant phenotype of 2D and 3D cultures of MCF-7 cells, and 3D cultures of MDA-MB-231 cells, by sequestering β-catenin away from nucleus.     

Synthesis,Biological Evaluation,Molecular Docking,ADME Predictions and QSAR Studies of Novel 1,2-Diazet and Pyrrole Derivatives as Anti-Inflammatory Agents

Russian Journal of Bioorganic Chemistry - Here we synthesized novel 1, 2-diazet and pyrrole derivatives and screened for their anti-inflammatory activity. In vivo anti-inflammatory evaluation...     

Isolation and characterization of a novel Lambda-like phage infecting the bloom-forming cyanobacteria Cylindrospermopsis raciborskii

Cylindrospermopsis raciborskii is a central bloom-forming cyanobacteria. However, despite its ecological significance, little is known of its interactions with the phages that infect it. Currently, only a single sequenced genome of a Cylindrospermopsis-infecting phage is publicly available. Here we describe the isolation and characterization of Cr-LKS3, a second phage infecting Cylindrospermopsis. Cr-LKS3 is a siphovirus with a higher genome similarity to prophages within heterotrophic bacteria genomes than to any other cyanophage/cyano-prophage, suggesting that it represents a novel cyanophage group. The function, order and orientation of the 72 genes in the Cr-LKS3 genome are highly similar to those of Escherichia virus Lambda (hereafter Lambda), despite the very low sequence similarity between these phages, showing high evolutionary convergence despite the substantial difference in host characteristics. Similarly to Lambda, the genome of Cr-LKS3 contains various genes that are known to be central to lysogeny, suggesting it can enter a lysogenic cycle. Cr-LKS3 has a unique ability to infect a host with a dramatically different GC content, without carrying any tRNA genes to compensate for this difference. This ability, together with its potential lysogenic lifestyle shed light on the complex interactions between C. raciborskii and its phages.     

IGFBP-2 and ?5: important regulators of normal and neoplastic mammary gland physiology

The insulin-like growth factor (IGF) axis plays an important role in mammary gland physiology. In addition, dysregulation of this molecular axis may have a causal role in the aetiology and development of breast cancer (BC). This report discusses the IGF axis in normal and neoplastic mammary gland with special reference to IGF binding proteins (IGFBPs) -2 and −5. We describe how these high affinity binders of IGF-1 and IGF-2 may regulate local actions of growth factors in an autocrine and/or paracrine manner and how they also have IGF-independent effects in mammary gland. We discuss clinical studies which investigate both the prognostic value of IGFBP-2 and −5 expression in BC and possible involvement of these genes in the development of resistance to adjuvant endocrine therapies.     

The possible neurobehavioral protective effects of natural antioxidant against phototoxicity attenuation of antimicrobial quinolone group in rats

The fluoroquinolones absorb light in the 320 to 330 nm ultraviolet A (UV‐A) wavelength and produce reactive oxygen species (ROS) such as superoxide anion, hydroxyl radical, and hydrogen peroxide; thus, the photodynamic generation of ROS may be the basis of phototoxicity of quinolones in human beings and animals. This study aimed to evaluate the damaging effects of UV‐A radiation at different periods of exposure on rats' brains administered with ciprofloxacin. Ciprofloxacin administration in UV‐A exposed animals exaggerated the brain‐oxidative stress biomarkers and decreased the locomotor activity. Exposure of rats to UV‐A for 60 minutes induced a significant increase of malondialdehyde (MDA), myeloperoxidase (MPO), and a decrease in the values of superoxide dismutase (SOD), glutathione (GSH) compared to a normal one; these changes were UV‐A exposure time–dependent. However, the administration of vitamin C to the UV‐60‐treated group decreased the values of MDA, MPO, and shifted the values of SOD, GSH toward the normal values. Vitamin C, probably due to its strong antioxidant properties, could improve and partially counteract the toxic effect of UV‐A on oxidative stress parameters and prevent the damage in rat's brain tissues.     

The actions of a charged melatonin receptor ligand, TMEPI, and an irreversible MT2 receptor agonist, BMNEP, on mouse hippocampal evoked potentials in vitro

We have previously determined that melatonin modulates hippocampal synaptic transmission in a biphasic way: an initial depression was followed by a recovery/amplification phase. Here we describe the influence of two novel melatonin receptor ligands, BMNEP (N-bromoacetyl-2-iodo-5-methoxytryptamine) and TMPEI (N-[2-(2-Trimethylammoniumethyleneoxy-7-methoxy)ethyl]propionamide iodide), on the population spike (PS) and excitatory postsynaptic potentials (EPSP) recorded from mouse hippocampal slices. BMNEP, which specifically alkylates and constitutively activates the MT2 melatonin receptor, mimicked the first phase of melatonin's action by irreversibly depressing both the PS and EPSP. TMPEI, a charged ligand of plasma membrane melatonin receptors, amplified those potentials in a manner similar to the effect of melatonin observed during the second, recovery phase. Melatonin had no influence on the potentials amplified by the action of TMPEI. Our results suggest that the biphasic, receptor-dependent action of melatonin and its analogs modulates the efficiency of the hippocampal glutamergic synapse and is most likely mediated through two different, sequentially occurring mechanisms.     

Organization of human papillomavirus productive cycle during neoplastic progression provides a basis for selection of diagnostic markers

The productive cycle of human papillomaviruses (HPVs) can be divided into discrete phases. Cell proliferation and episomal maintenance in the lower epithelial layers are followed by genome amplification and the expression of capsid proteins. These events, which occur in all productive infections, can be distinguished by using antibodies to viral gene products or to surrogate markers of their expression. Here we have compared precancerous lesions caused by HPV type 16 (HPV16) with lesions caused by HPV types that are not generally associated with human cancer. These include HPV2 and HPV11, which are related to HPV16 (supergroup A), as well as HPV1 and HPV65, which are evolutionarily divergent (supergroups E and B). HPV16-induced low-grade squamous intraepithelial lesions (CIN1) are productive infections which resemble those caused by other HPV types. During progression to cancer, however, the activation of late events is delayed, and the thickness of the proliferative compartment is progressively increased. In many HPV16-induced high-grade squamous intraepithelial lesions (CIN3), late events are restricted to small areas close to the epithelial surface. Such heterogeneity in the organization of the productive cycle was seen only in lesions caused by HPV16 and was not apparent when lesions caused by other HPV types were compared. By contrast, the order in which events in the productive cycle were initiated was invariant and did not depend on the infecting HPV type or the severity of disease. The distribution of viral gene products in the infected cervix depends on the extent to which the virus can complete its productive cycle, which in turn reflects the severity of cervical neoplasia. It appears from our work that the presence of such proteins in cells at the epithelial surface allows the severity of the underlying disease to be predicted and that markers of viral gene expression may improve cervical screening.     

Lipid droplet biogenesis is spatially coordinated at ER–vacuole contacts under nutritional stress

Eukaryotic cells store lipids in cytosolic organelles known as lipid droplets (LDs). Lipid droplet bud from the endoplasmic reticulum (ER), and may be harvested by the vacuole for energy during prolonged periods of starvation. How cells spatially coordinate LD production is poorly understood. Here, we demonstrate that yeast ER–vacuole contact sites (NVJs) physically expand in response to metabolic stress, and serve as sites for LD production. NVJ tether Mdm1 demarcates sites of LD budding, and interacts with fatty acyl‐CoA synthases at the NVJ periphery. Artificially expanding the NVJ through over‐expressing Mdm1 is sufficient to drive NVJ‐associated LD production, whereas ablating the NVJ induces defects in fatty acid‐to‐triglyceride production. Collectively, our data suggest a tight metabolic link between nutritional stress and LD biogenesis that is spatially coordinated at ER–vacuole contact sites.