Mechanism of homodimeric cytokine receptor activation and dysregulation by oncogenic mutations

Homodimeric class I cytokine receptors are assumed to exist as preformed dimers that are activated by ligand-induced conformational changes. We quantified the dimerization of three prototypic class I cytokine receptors in the plasma membrane of living cells by single-molecule fluorescence microscopy. Spatial and spatiotemporal correlation of individual receptor subunits showed ligand-induced dimerization and revealed that the associated Janus kinase 2 (JAK2) dimerizes through its pseudokinase domain. Oncogenic receptor and hyperactive JAK2 mutants promoted ligand-independent dimerization, highlighting the formation of receptor dimers as the switch responsible for signal activation. Atomistic modeling and molecular dynamics simulations based on a detailed energetic analysis of the interactions involved in dimerization yielded a mechanistic blueprint for homodimeric class I cytokine receptor activation and its dysregulation by individual mutations.</p

Embelin - a drug of antiquity: shifting the paradigm towards modern medicine

Introduction: Embelia ribes or Embelia tsjeriam-cottam, more commonly known as vidanga, is a type of ayurvedic medicine that has been used to treat various diseases for a number of years. Bright orange embelin-rich fruits have been well established as ethnomedicinals, for a number of years with their pharmacological actions attributed to their hydroxybenzoquinone active constituent. Embelin has become known specifically for its antihelminthic and contraceptive use. Areas covered: This drug evaluation provides a historical summary of embelin along with its therapeutic use, phytochemistry and toxicology. Embelin's pharmacotherapeutical properties are also discussed along with its molecular targets. It is hoped that this article will help to draw the attention of researchers and biopharmaceutical companies to the untapped potential in bioprospection for the development of new drugs. Expert opinion: Embelin is the only known non-peptide small-molecule X-linked inhibitor of the apoptosis protein (XIAP) - an anti-apoptotic protein considered a promising cancer therapeutic target. Embelin acts as an NF-kappa B blocker and potential suppressor of tumorigenesis. It also exhibits potent cytotoxic, antioxidant and cancer chemopreventive effects. Given the potential uses of embelin, it is recommended that further investigations take place to properly explore its pharmacological and clinical effects

Microtubule targeted therapeutics loaded polymeric assembled nanospheres for potentiation of antineoplastic activity

Polymeric nanoassemblies represent an attractive strategy for efficient cellular internalization of microtubule targeted anticancer drugs. Using dynamic light scattering, zeta potential, transmission electron microscopy and scanning electron microscopy, the physical properties and surface morphology of microtubule-binding PEGylated PLGA assembled nanospheres (100-200 nm) were analyzed. The present approach leads to strong internalization as observed by confocal laser scanning microscopy and transmission electron microscopy in hepatocarcinoma cells. The effect of these nanoassemblies on microtubules and mitosis were explored using immunofluorescence microscopy. The effects of these nanoassemblies on cancer cell proliferation and cell death revealed their antitumor enhancing effects. Perturbation of the microtubule assembly, mitosis and nuclear modulations potentiated the antineoplastic effects delivered via nanospheres in hepatocarcinoma cells. The extensive biomolecular and physical characterizations of the synthesized nanoassemblies will help to design potent therapeutic materials and the present approach can be applied to deliver microtubule-targeted drugs for liver cancer therapy

Intracellular interactions of electrostatically mediated layer-by-layer assembled polyelectrolytes based sorafenib nanoparticles in oral cancer cells

In this paper, we report the preparation of LbL-nanoSraf (100-300 nm) comprising of layer-by-layer (LbL) assembled polyelectrolytes dextran-sulfate/poly-L-arginine, with a multikinase inhibitor sorafenib (Sraf) encapsulated calcium carbonate (CaCO3) nanoparticles for oral cancer therapy in vitro. The zeta potential of LbL-nanoSraf exhibited a negative charge of the polyanionic dextran sulfate, which alternated with a positive charge of polycationic poly-L-arginine indicating a successful LbL assembly of the two polyelectrolyte bilayers on the CaCO3 nanoparticles. The LbL-nanoSraf exhibited an encapsulation efficiency of 61 +/- 4%. The LbL-nanoSraf was characterized using field-emission gun scanning electron microscopy, Xray powder diffraction, atomic force microscopy and confocal laser scanning microscopy. Confocal laser scanning microscopy, flow cytometry and transmission electron microscopic investigations showed the internalization of LbL-nanoSraf in human oral cancer (KB) cells. The LbL-nanoSraf exhibited more potent antiproliferative, apoptotic and antimigratory activities in KB cells than the free drug Sraf. The findings could promote the application of nano-sized LbL assembled polyelectrolytes for the delivery of Raf-kinase inhibitors and provide mechanistic insights for oral cancer therapy. (C) 2016 Elsevier B.V. All rights reserved

Embelin-Mediated Green Synthesis of Quasi-Spherical and Star-Shaped Plasmonic Nanostructures for Antibacterial Activity, Photothermal Therapy, and Computed Tomographic Imaging

Plasmonic nanostructures of silver and gold synthesized by conventional toxic and cumbersome methodologies raise huge concern for their clinical application, which necessitates the use of a greener approach. Herein, embelin, a benzoquinone derivative extracted from the fruits of Embelia tsjeriam-cottam, with immense medicinal value, is used as a reducing and stabilizing agent for the synthesis of quasi spherical gold and silver nanoparticles as well as gold nanostars. A sunlight-assisted synthesis resulted in embelin-stabilized silver nanoparticles of bimodal size distribution (similar to 3 and 15 nm) with potent antibacterial activity against Staphylococcus aureus and Escherichia coli. Similarly, embelin was also used for the synthesis of polyhedral gold nano particles of 12-15 nm in size and absorbance at 540 nm. These highly faceted and multitwinned gold nanoparticles facilitated the formation of 120 nm sized embelin-stabilized gold nanostars absorbing at NIR wavelength (800 nm). The embelin-stabilized nanoparticles demonstrated excellent compatibility toward cells and human blood. Additionally, the gold nanostars exhibited superior computed tomographic (CT) contrast characteristics and marked photothermal cytotoxicity toward oral epithelial carcinoma cells. This study thus proposes, for the first time, the synthesis of biocompatible plasmonic nanostructures using embelin and their potential use as antibacterial, CT imaging, and photothermal agents

Development of botanical principles for clinical use in cancer: Where are we lacking?

Development of drugs from plant sources (botanicals) for the treatment of cancer has not been successful in India, despite a plethora of medicinal plants and an equal number of experiments demonstrating anti-cancer activity of plant principles in vitro. There are several pitfalls in our approach to botanical drug development. Foremost is the lack of industry-academia collaborations in this field. Research goals in Indian academic institutions are generally short-term and mostly aimed at fulfilling the minimum requirements of a doctoral/MD or MPharm thesis. Secondly, quality assurance of herbal formulations is difficult to achieve and good manufacturing practices are expensive to implement. This could introduce bias during the biological evaluation of botanicals. A systematic approach covering a wide range of investigations including but not limited to mechanistic studies, potential herb-drug interactions, pharmacokinetics and bioavailability could help in the optimization of herbal formulations in the preclinical stage of development before they can be considered for clinical trials. Government initiatives such as Ayurveda, Unani, Siddha and Homeopathic have encouraged research in these areas, but are insufficient to promote focused and aggressive evaluation of potential herbs. Particular emphasis should be given to clinical pharmacokinetics, drug interactions and clinical trials in specific cancers for the evaluation of dosage, safety, efficacy and concomitant use with chemotherapy. Only such policies can result in meaningful evaluation of botanicals for cancer therapy