Probing the Pore Drug Binding Site of Microtubules with Fluorescent Taxanes: Evidence of Two Binding Poses

The pore site in microtubules has been studied with the use of Hexaflutax, a fluorescent probe derived from paclitaxel. The compound is active in cells with similar effects to paclitaxel, indicating that the pore may be a target to microtubule stabilizing agents. While other taxanes bind microtubules in a monophasic way, thus indicating a single type of sites, Hexaflutax association is biphasic. Analysis of the phases indicates that two different binding sites are detected, reflecting two different modes of binding, which could arise from different arrangements of the taxane or fluorescein moieties in the pore. Association of the 4-4-20 antifluorescein monoclonal antibody-Hexaflutax complex to microtubules remains biphasic, thus indicating that the two phases observed arise from two different poses of the taxane moiety.This work was supported in part by grant BIO2007-61336 from the Ministry of Science and Innovation to J.F.D., BIPPED-CM from Comunidad de Madrid to J.F.D. and J.M.A., and grant MOST No. 2006DFA31490 to W.S.F

A chemogenomic screening identifies CK2 as a target for pro-senescence therapy in PTEN-deficient tumours

Enhancement of cellular senescence in tumours triggers a stable cell growth arrest and activation of an antitumour immune response that can be exploited for cancer therapy. Currently, there are only a limited number of targeted therapies that act by increasing senescence in cancers, but the majority of them are not selective and also target healthy cells. Here we developed a chemogenomic screening to identify compounds that enhance senescence in PTEN-deficient cells without affecting normal cells. By using this approach, we identified casein kinase 2 (CK2) as a pro-senescent target. Mechanistically, we show that Pten loss increases CK2 levels by activating STAT3. CK2 upregulation in Pten null tumours affects the stability of Pml, an essential regulator of senescence. However, CK2 inhibition stabilizes Pml levels enhancing senescence in Pten null tumours. Taken together, our screening strategy has identified a novel STAT3-CK2-PML network that can be targeted for pro-senescence therapy for cancer

Biological Characterization and in Vivo Assessment of the Activity of a New Synthetic Macrocyclic Antifungal Compound

We recently identified a novel family of macrocyclic amidinoureas showing potent antifungal activity against Candida spp. In this study, we demonstrate the fungicidal effect of these compounds as well as their killing activity in a dose-dependent manner. Transcriptional analysis data indicate that our molecules induce a significant change in the transcriptome involving ATP binding cassette (ABC) transporter genes. Notably, experiments against Candida albicans mutants lacking those genes showed resistance to the compound, suggesting the involvement of ABC transporters in the uptake or intracellular accumulation of the molecule. To probe the mode of action, we performed fluorescence microscopy experiments on fungal cells treated with an ad-hoc synthesized fluorescent derivative. Fluorescence microscopy images confirm the ability of the compound to cross the membrane and show a consistent accumulation within the cytoplasm. Finally, we provide data supporting the in vivo efficacy in a systemic infection murine model setup with a drug-resistant strain of C. albicans

Possible binding site for paclitaxelat microtubule pores

Taxanes and other microtubule-stabilizing agents comprise an important class of anticancer drugs. It is well known that taxanes act by binding to beta-tubulin on the lumenal side of microtubules. However, experimental evidence obtained in recent years led to the hypothesis of an external site on the microtubule wall to which taxanes and other microtubule-stabilizing agents could bind before being internalized to their lumenal site. In the present study, different computational techniques were combined to explore the possible existence of an exposed and easily accessible binding site for microtubule-stabilizing agents on the outside of microtubules. The results obtained indicate that the conformational rearrangement of the H6-H7 hoop of beta-tubulin can form a suitable pocket on the outer microtubule surface, and that paclitaxel can efficaciously interact with this newly-proposed binding site

A fast virtual screening approach to identify structurally diverse inhibitors of trypanothione reductase

Trypanothione reductase (TryR) is one of the favorite targets for those designing drugs for the treatment of Chagas disease. We present the application of a fast virtual screening approach for designing hit compounds active against TryR. Our protocol combines information derived from structurally known inhibitors and from the TryR receptor structure. Five structurally diverse hit compounds active against TryR and holding promise for the treatment of Chagas disease are reported

Linear guanidine derivatives, methods of preparation and uses thereof

The present invention relates to linear guanidine derivatives, methods of preparation, uses and pharmaceutical compositions thereof. The compounds of Formulas 1 or 2 exhibit high antimicrobial activity against Gram positive and Gram negative bacteria

Persistence of poliovirus genome in polio survivors diagnosed with post-polio syndrome

Background: Persistent poliovirus (PV) infection has been reported frequently in individuals with B lymphocyte deficiency (and low or absent serum immunoglobulins). The origin of PPS is poorly understood, but inflammation in meninges, spinal cord and muscles has been noticed (Semino-Mora & Dalakas, 1998). Inflammatory infiltrates suggest: persistent PV infection, autoimmune attack on CNS targets, increased vulnerability of CNS to further infections. The possibility of persistent PV infection was investigated in a cohort of PPS patients. Methods: Patients were diagnosed according to EFNS criteria: PPS cases (n=112), stable polio cases (n=15). Family members of PPS patients (n=50) and non-polio controls (n=57) were also investigated. Specimens: cerebrospinal fluid, peripheral blood leukocytes, assorted live cells (duodenal mucosa, skeletal muscle, peripheral nerve). Samples were co-cultured with PVsusceptible cell lines, then poliovirus-specific RT-PCR assays were performed. Results: Poliovirus genome was detected in 93/112 (83%) PPS patients, 4/15 (27%) stable polio cases, 2/107 (2%) controls. Type 1 poliovirus was found most frequently (59%), followed by type 2 (13%) and type 3 (11%). Some cases could not be typed. Epithelial cell lines infected with PV from PPS patients produced PV capsid proteins and enhanced levels of the chemokine MCP-1. Serum immunoglobulin levels were measured in cases and controls. IgG1, IgG2, IgG4 and IgA were significantly reduced in PPS cases and their family members. IgM levels and titers of poliovirus neutralizing antibodies were not significantly different among PPS cases and controls. Conclusions: Low-level PV activity was detected at high frequency in PPS patients decades after the acute attack and might play a pathogenetic role. PV infection is not transmitted by PPS patients to their family members, a relevant finding for public health. Effective treatments for PPS are missing (Koopman et al., 2011). In order to avoid PPS or block its progression, identification of individuals with chronic PV infection might lead to treatment with intravenous human IgG preparations, antiviral drugs, anti-PV antibodies. Antiviral treatments are under development and may hold the potential for eradicating chronic PV infection

Synthesis, biological evaluation and molecular modeling of 1,2,3-triazole analogs of combretastatin A-1.

The synthesis, cytotoxicity, inhibition of tubulin polymerization data and anti-angiogenetic effects of seven 1,5-disubstituted 1,2,3-triazole analogs and two 1,4-disubstituted 1,2,3-triazole analogs of combretastatin A-1 (1) are reported herein. The biological studies revealed that the 1,5-disubstituted 1,2,3-triazoles 3-methoxy-6-(1-(3,4,5-trimethoxyphenyl)-1H-1,2,3-triazol-5-yl)benzene-1,2-diol (6), 3-methoxy-6-(1-(3,4,5-trimethoxyphenyl)-1H-1,2,3-triazol-5-yl)benzene-1,2-diamine (8) and 5-(2,3-difluoro-4-methoxyphenyl)-1-(3,4,5-trimethoxyphenyl)-1H-1,2,3-triazole (9) were the three most active compounds regarding inhibition of both tubulin polymerization and angiogenesis. Molecular modeling studies revealed that combretastatins 1 and 2 and analogs 5-11 could be successfully docked into the colchicine binding site of α,β-tubulin

Preparation of new macrocyclic amidinourea derivatives as chitinase inhibitors

The present invention relates to macrocyclic amidinourea derivatives of formula 8, methods of preparation and uses thereof, pharmaceutical compositions in particular to be used as chitinase inhibitors in the treatment of a fungal infectio

New macrocyclic amidinourea derivatives, methods of preparation and uses thereof as chitinase inhibitors

The present invention relates to macrocyclic amidinourea derivatives of formula 8, methods of preparation and uses thereof, pharmaceutical compositions in particular to be used as chitinase inhibitors in the treatment of a fungal infection