Griseofulvin stabilizes microtubule dynamics, activates p53 and inhibits the proliferation of MCF-7 cells synergistically with vinblastine

<p>Abstract</p> <p>Background</p> <p>Griseofulvin, an antifungal drug, has recently been shown to inhibit proliferation of various types of cancer cells and to inhibit tumor growth in athymic mice. Due to its low toxicity, griseofulvin has drawn considerable attention for its potential use in cancer chemotherapy. This work aims to understand how griseofulvin suppresses microtubule dynamics in living cells and sought to elucidate the antimitotic and antiproliferative action of the drug.</p> <p>Methods</p> <p>The effects of griseofulvin on the dynamics of individual microtubules in live MCF-7 cells were measured by confocal microscopy. Immunofluorescence microscopy, western blotting and flow cytometry were used to analyze the effects of griseofulvin on spindle microtubule organization, cell cycle progression and apoptosis. Further, interactions of purified tubulin with griseofulvin were studied <it>in vitro </it>by spectrophotometry and spectrofluorimetry. Docking analysis was performed using autodock4 and LigandFit module of Discovery Studio 2.1.</p> <p>Results</p> <p>Griseofulvin strongly suppressed the dynamic instability of individual microtubules in live MCF-7 cells by reducing the rate and extent of the growing and shortening phases. At or near half-maximal proliferation inhibitory concentration, griseofulvin dampened the dynamicity of microtubules in MCF-7 cells without significantly disrupting the microtubule network. Griseofulvin-induced mitotic arrest was associated with several mitotic abnormalities like misaligned chromosomes, multipolar spindles, misegregated chromosomes resulting in cells containing fragmented nuclei. These fragmented nuclei were found to contain increased concentration of p53. Using both computational and experimental approaches, we provided evidence suggesting that griseofulvin binds to tubulin in two different sites; one site overlaps with the paclitaxel binding site while the second site is located at the αβ intra-dimer interface. In combination studies, griseofulvin and vinblastine were found to exert synergistic effects against MCF-7 cell proliferation.</p> <p>Conclusions</p> <p>The study provided evidence suggesting that griseofulvin shares its binding site in tubulin with paclitaxel and kinetically suppresses microtubule dynamics in a similar manner. The results revealed the antimitotic mechanism of action of griseofulvin and provided evidence suggesting that griseofulvin alone and/or in combination with vinblastine may have promising role in breast cancer chemotherapy.</p

Dexamethasone release from uniform sized nanoengineered alginate microspheres

The main objective of this work is to develop a novel technology based on nanoengineered alginate microspheres made using the droplet generator technique for controlled delivery of an immunomodulating agent at the site of implantation. Uniform sized alginate microspheres have been prepared using a commercially available droplet generator. SEM and optical micrographs confirmed the structure and spherecity of the prepared alginate microspheres. Release studies, completed on uncoated alginate microspheres, did not provide the desired profile. Layer-by-Layer (LbL) self assembly technique was further implemented on the uncoated alginate microspheres using standard polyelectrolyte pair. SEM, zeta potential measurements and QCM measurements were used to confirm the nanofilm coating on the alginate microspheres. Release studies conducted on the uncoated dexamethasone alginate microspheres demonstrate a cumulative release of 78% of initially encapsulated dexamethasone as compared to one and two bilayer coated microspheres, which demonstrate a release of 40% and 32% respectively. Thus, the application of nanofilm coating helped in reducing the initial burst release, thereby providing a means to control the release of drug over a longer period of time

Polyelectrolyte-coated alginate microspheres as drug delivery carriers for dexamethasone release

Alginate microspheres loaded with dexamethasone were prepared by the droplet generator technique. Important parameters affecting drug release, including initial drug content, the type of polyelectrolyte coating, and a combination of different ratios of coated and uncoated microspheres were investigated to achieve in vitro dexamethasone delivery with approximately zero order release kinetics, releasing up to 100% of entrapped drug within 1 month, wherein dexamethasone released at a steady rate of 4.83 mu g/day after an initial burst release period. These findings imply that these polyelectrolyte-coated alginate microspheres show promise as release systems to improve biocompatibility and prolong lifetime of implantable glucose sensors

Advancements in nano-enabled therapeutics for neuroHIV management

Ajeet Kaushik, Rahul Dev Jayant, Madhavan Nair Center for Personalized NanoMedicine, Institute of NeuroImmune Pharmacology, Department of Immunology, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA Abstract: This viewpoint is a global call to promote fundamental and applied research aiming toward designing smart nanocarriers of desired properties, novel noninvasive strategies to open the blood&ndash;brain barrier (BBB), delivery/release of single/multiple therapeutic agents across the BBB to eradicate neurohuman immunodeficiency virus (HIV), strategies for on-demand site-specific release of antiretroviral therapy, developing novel nanoformulations capable to recognize and eradicate latently infected HIV reservoirs, and developing novel smart analytical diagnostic tools to detect and monitor HIV infection. Thus, investigation of novel nanoformulations, methodologies for site-specific delivery/release, analytical methods, and diagnostic tools would be of high significance to eradicate and monitor neuroacquired immunodeficiency syndrome. Overall, these developments will certainly help to develop personalized nanomedicines to cure HIV and to develop smart HIV-monitoring analytical systems for disease management. Keywords: nanotherapeutics, personalized nanomedicine, smart monitoring analytical systems, HIV disease managemen

Nano-in-micro alginate based hybrid particles

Novel template containing 'Nanoparticles (gelatin and CaCO(3)) embedded in Microspheres' ('Nano-in-micro') was developed using atomization. Dexamethasone loaded gelatin nanoparticles, fluorescein isothiocyanate-dextran (FITC-dex) loaded CaCO(3) nanoparticles and alginate based 'Nano-in-micro' system were prepared and characterized using optical microscopy, SEM, TEM. DLS, zeta potential, CLSM and FTIR. The results indicate that spherical, non-aggregating, 'nano-in-micro' particles (5-60 mu m) can be prepared using atomization technique. Dexamethasone release from gelatin nanoparticles and 'nano-in-micro' systems indicated a decrease in burst release in the order: uncoated (24%) > coated (18%) > 'nano-in-micro' system (1:4 ratio) (17%). The sustained release decreased in order of 'nano-in-micro' (1:4 ratio) (14 days) > coated nanoparticles (9 days)> uncoated nanoparticles (4 days) for 95% drug release. FITC-dex loading and release from CaCO(3) nanoparticles were found to be molecular weight dependent. Thus, 'nano-in-micro' systems show possibility for use as drug release vehicles, biosensors and multifunctional systems

Cholesterol Biosensors Based on Oxygen Sensing Alginate-Silica Microspheres

Cholesterol determination in body is important in diagnosis of diseases like coronary heart disease, arteriosclerosis, diabetes, and obstructive jaundice. This research aims at developing fluorimetric cholesterol biosensors based on self-assembled mesoporous alginate-silica (Algilica) microspheres. For preparing the biosensor, Pt-(II)-octaethylporphine (PtOEP; oxygen sensitive metalloporphyrin) dye has been loaded in the Algilica microspheres using the solvent-mediated precipitation method. Cholesterol oxidase (ChOx) was then covalently conjugated to PtOEP/Algilica microspheres using EDC and NHS reagents. PtOEP dye and enzyme encapsulation, activity and stability were then analyzed. Layer-by-layer self-assembly was finally performed using PAH and PSS polyelectrolytes to minimize leaching of the biosensor components. The prepared biosensor exhibited linearity over a range of 0.77-2.5mM O(2) (KSV: 0.097/mM of O(2)) obtained using from Stern-Volmer plots. The biosensor response to standard cholesterol displayed a linear analytical range from 1.25 to 10mM of cholesterol with regression coefficient of 0.996 (1.25-3.75 mM), 0.976 (1.25-6 mM), and 0.959 (1.25-10mM) and response time of 10 min. Thus, the prepared cholesterol biosensor shows great potential in the diagnosis of hypercholesterolemia. Biotechnol. Bioeng. 2011; 108: 2011-2021. (C) 2011 Wiley Periodicals, Inc

Sustained-release nanoART formulation for the&nbsp;treatment of neuroAIDS

Rahul Dev Jayant, Venkata SR Atluri, Marisela Agudelo, Vidya Sagar, Ajeet Kaushik, Madhavan Nair Center for Personalized Nanomedicine, Department of Immunology, Herbert Wertheim College of Medicine, Florida International University, Miami, FL,&nbsp;USA Abstract: A novel approach was developed for the coencapsulation of an anti-HIV drug (tenofovir) and a latency-breaking agent (vorinostat), using magnetically guided layer-by-layer (LbL) assembled nanocarriers for the treatment of neuroAIDS. Ultrasmall iron oxide (Fe3O4) nanoparticles (10&plusmn;3 nm) were synthesized and characterized. The LbL technique was used to achieve a sustained release profile, and application of 2 bilayers ([tenofovir+dextran sulphate]2+vorinostat) to magnetic nanoparticles resulted in a 2.8 times increase in drug (tenofovir) loading and also resulted in an increase in the drug release period by 30-fold, with 100% drug release in sustained manner over a period of 5 days with the simultaneous stimulation of latent HIV expression. Nanoformulation showed a good blood&ndash;brain barrier transmigration ability (37.95%&plusmn;1.5%) with good in vitro antiviral efficacy (~33% reduction of p24 level) over a period of 5 days after HIV infection in primary human astrocytes, with good cell viability (&gt;90%). Hence, LbL arrangements of drugs on magnetic nanoparticles provides sustained release and, therefore, may improve the patient&rsquo;s adherence to therapy and lead to better compliance. Keywords: layer-by-layer, magnetic nanocarriers, blood&ndash;brain barriers, neuroAIDS, sustained release, anti-HIV drug, latenc