Tryptone-stabilized silver nanoparticles' potential to mitigate planktonic and biofilm growth forms of Serratia marcescens.

Several microbial pathogens are capable of forming biofilms. These microbial communities pose a serious challenge to the healthcare sector as they are quite difficult to combat. Given the challenges associated with the antibiotic-based management of biofilms, the research focus has now been shifted towards finding alternate treatment strategies that can replace or complement the antibacterial properties of antibiotics. The field of nanotechnology offers several novel and revolutionary approaches to eradicate biofilm-forming microbes. In this study, we evaluated the antibacterial and antibiofilm efficacy of in-house synthesized, tryptone-stabilized silver nanoparticles (Ts-AgNPs) against the superbug Serratia marcescens. The nanoparticles were of spherical morphology with an average hydrodynamic diameter of 170 nm and considerable colloidal stability with a Zeta potential of - 24 ± 6.15 mV. Ts-AgNPs showed strong antibacterial activities with a minimum inhibitory concentration (MIC50) of 2.5 µg/mL and minimum bactericidal concentration (MBC) of 12.5 µg/mL against S. marcescens. The nanoparticles altered the cell surface hydrophobicity and inhibited biofilm formation. The Ts-AgNPs were also effective in distorting pre-existing biofilms by degrading the extracellular DNA (eDNA) component of the extracellular polymeric substance (EPS) layer. Furthermore, reduction in quorum-sensing (QS)-induced virulence factors produced by S. marcescens indicated that Ts-AgNPs attenuated the QS pathway. Together, these findings suggest that Ts-AgNPs are an important anti-planktonic and antibiofilm agent that can be explored for both the prevention and treatment of infections caused by S. marcescens.

Cell death mechanisms in eukaryotes.

Like the organism they constitute, the cells also die in different ways. The death can be predetermined, programmed, and cleanly executed, as in the case of apoptosis, or it can be traumatic, inflammatory, and sudden as many types of necrosis exemplify. Nevertheless, there are a number of cell deaths-some of them bearing a resemblance to apoptosis and/or necrosis, and many, distinct from each-that serve a multitude of roles in either supporting or disrupting the homoeostasis. Apoptosis is coordinated by death ligands, caspases, b-cell lymphoma-2 (Bcl-2) family proteins, and their downstream effectors. Events that can lead to apoptosis include mitotic catastrophe and anoikis. Necrosis, although it has been considered an abrupt and uncoordinated cell death, has many molecular events associated with it. There are cell death mechanisms that share some standard features with necrosis. These include methuosis, necroptosis, NETosis, pyronecrosis, and pyroptosis. Autophagy, generally a catabolic pathway that operates to ensure cell survival, can also kill the cell through mechanisms such as autosis. Other cell-death mechanisms include entosis, ferroptosis, lysosome-dependent cell death, and parthanatos.

Perturbation of tubulin structure by stellate gold nanoparticles retards MDA-MB-231 breast cancer cell viability.

Gold nanoparticles (GNPs) of different sizes and shapes have been investigated extensively for their therapeutic potential against several diseases including cancer. However, the mechanisms with which they affect the cells are yet to be fully comprehended. In this study, we report the strong antiproliferative potential of novel, star-shaped ("stellate") GNPs that target tubulin-the building-block protein of the cytoskeletal filaments called microtubules-and disrupt microtubule network integrity. The stellate GNPs ("sGNPs") were synthesized from tryptone-stabilized GNPs ("tGNPs") and characterized by various spectroscopy methods combined with high-resolution transmission electron microscopy. Among a panel of cancer cell lines tested, they showed strong antiproliferative and anti-clonogenic efficacy against MDA-MB-231 cells. The antiproliferative mechanism of the sGNPs involves perturbation of the secondary and tertiary conformation of tubulin as evidenced by far-UV circular dichroism and anilinonaphthalene sulphate-binding assays. The structural perturbation of tubulin retarded its assembly competence as evidenced by polymer mass analysis and electron microscopy imaging of tubulin assembled in vitro and by immunofluorescence visualization of the cellular microtubules. The treated cells also induced cell cycle arrest at G1 phase. Taken together, our data suggest that sGNPs are potent, tubulin-targeted antiproliferative particles that can be evaluated further for their anticancer potential.

Tryptone-stabilized gold nanoparticles target tubulin and inhibit cell viability by inducing an unusual form of cell cycle arrest.

Gold nanoparticles have been investigated extensively for their molecular mechanisms of action and anticancer potential. We report a novel, tubulin-targeted antiproliferative mechanism of action of tryptone-stabilized gold nanoparticles (TsAuNPs). TsAuNPs, synthesized using HAuCl4·3H2O and tryptone and characterized by a variety of spectroscopic methods and transmission electron microscopy, were found to be inhibitory to viability of human pancreatic (PANC-1), cervical (HeLa), and breast (MDA-MB-231) cancer cell lines in a concentration-dependent manner, with highest efficacy against PANC-1 cells. The particles strongly inhibited the clonogenic propagation of PANC-1 cells. TsAuNPs-mediated inhibition of cell viability involved an unusual mode of cell cycle arrest (arrest at both G0/G1 phase and S-phase) followed by apoptosis. In vitro, TsAuNPs bound purified tubulin, competitively inhibited anilinonaphthalene sulfonate binding to tubulin, and suppressed tubulin assembly. In cells, tubulin-TsAuNPs interactions were manifested as a disrupted microtubule network, defective reassembly of cold-disassembled microtubules, and induction of tubulin acetylation. Our data indicate that TsAuNPs inhibit cell viability by inducing differential cell cycle arrest possibly through disrupted dynamicity of cellular microtubules.

Safranal Inhibits HeLa Cell Viability by Perturbing the Reassembly Potential of Microtubules.

Saffron, a spice from Crocus sativus, has been known for its health benefits and medicinal properties. Safranal is a component of saffron and is known for its antioxidant and anticancer properties. In this study, we elucidated a possible tubulin-targeted antiproliferative mechanism of action of safranal. In vitro, the compound perturbed secondary structure of tubulin without altering net microtubule polymer mass. It inhibited HeLa cell viability in a concentration-dependent manner, with minimal damage to cellular microtubules. However, it strongly inhibited recovery of microtubule network after cold-induced disassembly, indicating its ability to interfere with the nucleation potential of tubulin. Further, as the acetylation pattern of the safranal-treated microtubules revealed, unlike many tubulin-targeted agents, the compound did not appear to induce persistent stabilization of microtubules. Our data shows an unusual, tubulin-targeted antiproliferative mechanism of safranal. Copyright © 2017 John Wiley & Sons, Ltd.

Chemical synthesis, pharmacological evaluation and in silico analysis of new 2,3,3a,4,5,6-hexahydrocyclopenta[c]pyrazole derivatives as potential anti-mitotic agents.

We have synthesized new, biologically active mono- and di-substituted 2,3,3a,4,5,6-hexahydrocyclopenta[c]pyrazole derivatives bearing electron withdrawing groups and electron donating groups. These derivative structures were characterized by their spectral and analytical data. The newly synthesized hexahydropyrazole analogues were evaluated for their in vitro anticancer activity against breast and lung cancer cell lines using a cytotoxicity bioassay. To understand their mechanism of action, tubulin binding assays were performed which pointed to their binding to microtubules in a mode similar to but not identical to colchicine, as evidenced by their KD value evaluation. Computational docking studies also suggested binding near the colchicine binding site on tubulin. These results were further confirmed by colchicine-binding assays on the most active compounds, which indicated that they bound to tubulin near but not at the colchicine site. The moderate cytotoxic effects of these compounds may be due to the presence of electron donating groups on the para-position of the phenyl ring, along with the hexahydropyrazole core nucleus. The observed anti-cancer activity based on inhibition of microtubule formation may be helpful in designing more potent compounds with a hexahydropyrazole moiety.

Effects of eribulin on microtubule binding and dynamic instability are strengthened in the absence of the ßIII tubulin isotype.

Eribulin mesylate (Halaven) is a microtubule-targeted anticancer drug used to treat patients with metastatic breast cancer who have previously received a taxane and an anthracycline. It binds at the plus ends of microtubules and has been shown to suppress plus end growth selectively. Because the class III ß tubulin isotype is associated with resistance to microtubule targeting drugs, we sought to determine how ßIII tubulin might mechanistically influence the effects of eribulin on microtubules. We found that while [(3)H]eribulin bound to bovine brain soluble tubulin depleted of ßIII tubulin in a manner similar to that of unfractionated tubulin, it bound to plus ends of microtubules that were depleted of ßIII-depleted tubulin with a maximal stoichiometry (20 ± 3 molecules per microtubule) higher than that of unfractionated microtubules (9 ± 2 molecules per microtubule). In addition, eribulin suppressed the dynamic instability behavior of ßIII-depleted microtubules more strongly than and in a manner different from that of microtubules containing ßIII tubulin. Specifically, with ßIII tubulin present in the microtubules, 100 nM eribulin suppressed the growth rate by 32% and marginally reduced the catastrophe frequency (by 17%) but did not modulate the rescue frequency. However, in the absence of ßIII tubulin, eribulin not only reduced the growth rate but also strongly reduced the shortening rate (by 43%) and the catastrophe and the rescue frequencies (by 49 and 32%, respectively). Thus, when present in microtubules, ßIII tubulin substantially weakens the effects of eribulin.

Design, synthesis and biological evaluation of di-substituted noscapine analogs as potent and microtubule-targeted anticancer agents.

Noscapine is an opium-derived kinder-gentler microtubule-modulating drug, currently in Phase I/II clinical trials for cancer chemotherapy. Here, we report the synthesis of four more potent di-substituted brominated derivatives of noscapine, 9-Br-7-OH-NOS (2), 9-Br-7-OCONHEt-NOS (3), 9-Br-7-OCONHBn-NOS (4), and 9-Br-7-OAc-NOS (5) and their chemotherapeutic efficacy on PC-3 and MDA-MB-231 cells. The four derivatives were observed to have higher tubulin binding activity than noscapine and significantly affect tubulin polymerization. The equilibrium dissociation constant (KD) for the interaction between tubulin and 2, 3, 4, 5 was found to be, 55±6µM, 44±6µM, 26±3µM, and 21±1µM respectively, which is comparable to parent analog. The effects of these di-substituted noscapine analogs on cell cycle parameters indicate that the cells enter a quiescent phase without undergoing further cell division. The varying biological activity of these analogs and bulk of substituent at position-7 of the benzofuranone ring system of the parent molecule was rationalized utilizing predictive in silico molecular modeling. Furthermore, the immunoblot analysis of protein lysates from cells treated with 4 and 5, revealed the induction of apoptosis and down-regulation of survivin levels. This result was further supported by the enhanced activity of caspase-3/7 enzymes in treated samples compared to the controls. Hence, these compounds showed a great potential for studying microtubule-mediated processes and as chemotherapeutic agents for the management of human cancers.

Rational design of biaryl pharmacophore inserted noscapine derivatives as potent tubulin binding anticancer agents.

We have strategically designed a series of noscapine derivatives by inserting biaryl pharmacophore (a major structural constituent of many of the microtubule-targeting natural anticancer compounds) onto the scaffold structure of noscapine. Molecular interaction of these derivatives with α,ß-tubulin heterodimer was investigated by molecular docking, molecular dynamics simulation, and binding free energy calculation. The predictive binding affinity indicates that the newly designed noscapinoids bind to tubulin with a greater affinity. The predictive binding free energy (ΔG(bind, pred)) of these derivatives (ranging from -5.568 to -5.970 kcal/mol) based on linear interaction energy (LIE) method with a surface generalized Born (SGB) continuum solvation model showed improved binding affinity with tubulin compared to the lead compound, natural α-noscapine (-5.505 kcal/mol). Guided by the computational findings, these new biaryl type α-noscapine congeners were synthesized from 9-bromo-α-noscapine using optimized Suzuki reaction conditions for further experimental evaluation. The derivatives showed improved inhibition of the proliferation of human breast cancer cells (MCF-7), human cervical cancer cells (HeLa) and human lung adenocarcinoma cells (A549), compared to natural noscapine. The cell cycle analysis in MCF-7 further revealed that these compounds alter the cell cycle profile and cause mitotic arrest at G2/M phase more strongly than noscapine. Tubulin binding assay revealed higher binding affinity to tubulin, as suggested by dissociation constant (Kd) of 126 ± 5.0 µM for 5a, 107 ± 5.0 µM for 5c, 70 ± 4.0 µM for 5d, and 68 ± 6.0 µM for 5e compared to noscapine (Kd of 152 ± 1.0 µM). In fact, the experimentally determined value of ΔG(bind, expt) (calculated from the Kd value) are consistent with the predicted value of ΔG(bind, pred) calculated based on LIE-SGB. Based on these results, one of the derivative 5e of this series was used for further toxicological evaluation. Treatment of mice with a daily dose of 300 mg/kg and a single dose of 600 mg/kg indicates that the compound does not induce detectable pathological abnormalities in normal tissues. Also there were no significant differences in hematological parameters between the treated and untreated groups. Hence, the newly designed noscapinoid, 5e is an orally bioavailable, safe and effective anticancer agent with a potential for the treatment of cancer and might be a candidate for clinical evaluation.

The taccalonolides and paclitaxel cause distinct effects on microtubule dynamics and aster formation.

BACKGROUND: Microtubule stabilizers suppress microtubule dynamics and, at the lowest antiproliferative concentrations, disrupt the function of mitotic spindles, leading to mitotic arrest and apoptosis. At slightly higher concentrations, these agents cause the formation of multiple mitotic asters with distinct morphologies elicited by different microtubule stabilizers. RESULTS: We tested the hypothesis that two classes of microtubule stabilizing drugs, the taxanes and the taccalonolides, cause the formation of distinct aster structures due, in part, to differential effects on microtubule dynamics. Paclitaxel and the taccalonolides suppressed the dynamics of microtubules formed from purified tubulin as well as in live cells. Both agents suppressed microtubule dynamic instability, with the taccalonolides having a more pronounced inhibition of microtubule catastrophe, suggesting that they stabilize the plus ends of microtubules more effectively than paclitaxel. Live cell microscopy was also used to evaluate the formation and resolution of asters after drug treatment. While each drug had similar effects on initial formation, substantial differences were observed in aster resolution. Paclitaxel-induced asters often coalesced over time resulting in fewer, larger asters whereas numerous compact asters persisted once they were formed in the presence of the taccalonolides. CONCLUSIONS: We conclude that the increased resistance of microtubule plus ends to catastrophe may play a role in the observed inability of taccalonolide-induced asters to coalesce during mitosis, giving rise to the distinct morphologies observed after exposure to these agents.

Induction of autophagy-dependent and caspase- and microtubule-acetylation-independent cell death by phytochemical-stabilized gold nanopolygons in colorectal adenocarcinoma cells.

Collective functionalization of the phytochemicals of medicinal herbs on nanoparticles is emerging as a potential cancer therapeutic strategy. This study presents the facile synthesis of surface-functionalized gold nanoparticles using Bacopa monnieri (Brahmi; Bm) phytochemicals and their therapeutically relevant mechanism of action in the colorectal cancer cell line, HT29. The nanoparticles were characterized using UV-visible spectroscopy, TEM-EDAX, zeta potential analysis, TGA, FTIR and 1H NMR spectroscopy, and HR-LC-MS. The particles (Bm-GNPs) were of polygonal shape and were stable against aggregation. They entered the target cells and inhibited the viability and clonogenicity of the cells with eight times more antiproliferative efficacy (25 ± 1.5 µg mL-1) than Bm extract (Bm-EX). In vitro studies revealed that Bm-GNPs bind tubulin (a protein crucial in cell division and a target of anticancer drugs) and disrupt its helical structure without grossly altering its tertiary conformation. Like other antitubulin agents, Bm-GNPs induced G2/M arrest and ultimately killed the cells, as confirmed using flow cytometry analyses. ZVAD-FMK-mediated global pan-caspase inhibition and the apparent absence of cleaved caspase-3 in treated cells indicated that the death did not involve the classic apoptosis pathway. Cellular ultrastructure analyses, western immunoblots, and in situ immunofluorescence visualization of cellular microtubules revealed microtubule-acetylation-independent induction of autophagy as the facilitator of cell death. Together, the data indicate strong antiproliferative efficacy and a possible mechanism of action for these designer nanoparticles. Bm-GNPs, therefore, merit further investigations, including preclinical evaluations, for their therapeutic potential as inducers of non-apoptotic cell death.

Biochemical and in silico analysis of the binding mode of erastin with tubulin.

Erastin (ERN) is a small molecule that induces different forms of cell death. For example, it has been reported to induce ferroptosis by disrupting tubulin subunits that maintain the voltage-dependent anion channels (VDACs) of mitochondria. Although its possible binding to tubulin has been suggested, the fine details of the interaction between ERN and tubulin are poorly understood. Using a combination of biochemical, cell-model and in silico approaches, we elucidate the interactions of ERN with tubulin and their biological manifestations. After confirming ERN's antiproliferative efficacy (IC50, 20 ± 3.2 M) and induction of cell death in the breast cancer cell line MDA-MB-231, the binding interactions of ERN with tubulin were examined. ERN bound to tubulin in a concentration-dependent manner, disorganizing the structural integrity of the protein, as substantiated via the tryptophan-quenching assay and the aniline-naphthalene sulfonate binding assay, respectively. In silico studies based on molecular docking revealed a docking score of -5.863 kcal/mol, suggesting strong binding interactions of ERN with tubulin. Additionally, molecular dynamics simulation and Molecular Mechanics Poisson-Boltzmann Surface Area (MM-PBSA) analyses evinced the binding free energy (ΔGbinding) of -31.235 kcal/mol, substantiating strong binding affinity of ERN with tubulin. Ligplot analysis showed hydrogen bonding with specific amino acids (Asn A226, Thr A223, Gln B247 and Val B355). QikProp-based ADME (absorption, distribution, metabolism and excretion) assessment showed considerable therapeutic potential for ERN.Communicated by Ramaswamy H. Sarma.

Antiproliferative efficacy and mechanism of action of garlic phytochemicals-functionalized gold nanoparticles in triple-negative breast cancer cells.

Fabrication of gold nanoparticles (GNPs) with phytochemicals is an emerging green nanotechnology approach with therapeutic implications. Garlic, known for its culinary and medicinal properties, has been extensively investigated for its anticancer properties. Here, we report a method to substantially enhance the antiproliferative potency of garlic by functionalizing its phytochemicals to GNPs and demonstrate a possible mechanism of action of these nanoparticles in the triple-negative breast cancer cell line, MDA-MB-231. Garlic gold nanoparticles (As-GNPs) were synthesized using garlic extract (As-EX) and gold chloride and characterized using a variety of spectroscopy techniques, and transmission electron microscopy (TEM). Compared to As-EX, which has a negligible effect on the viability of the cells, As-GNPs inhibited cell viability with an IC50of 0.310 ± 0.04 mg ml-1and strongly inhibited the clonogenic and migratory propensities of these cells. As indicated by TEM, the As-GNPs entered the cells via endocytosis and dispersed in the cellular milieu. Since tubulin, the protein involved in cell division, is a verified target for several antiproliferative drugs, we next examined whether the As-GNPs interact with this protein. The As-GNPs showed concentration-dependent binding to purified tubulin, slightly but consistently perturbing its secondary helical integritywithout grossly damaging the tertiary structure of the protein or the net polymer mass of the microtubules, as indicated by a tryptophan-quenching assay, far UV-circular dichroism spectroscopy, anilinonaphthalene sulfonate-binding assay, and polymer mass analysis, respectively. In cells, As-GNPs killed the cancer cells without cell cycle arrest, as evidenced by flow cytometry.

Therapeutic and diagnostic applications of carbon nanotubes in cancer: recent advances and challenges.

Carbon nanotubes (CNTs) are allotropes of carbon, composed of carbon atoms forming a tube-like structure. Their high surface area, chemical stability, and rich electronic polyaromatic structure facilitate their drug-carrying capacity. Therefore, CNTs have been intensively explored for several biomedical applications, including as a potential treatment option for cancer. By incorporating smart fabrication strategies, CNTs can be designed to specifically target cancer cells. This targeted drug delivery approach not only maximizes the therapeutic utility of CNTs but also minimizes any potential side effects of free drug molecules. CNTs can also be utilised for photothermal therapy (PTT) which uses photosensitizers to generate reactive oxygen species (ROS) to kill cancer cells, and in immunotherapeutic applications. Regarding the latter, for example, CNT-based formulations can preferentially target intra-tumoural regulatory T-cells. CNTs also act as efficient antigen presenters. With their capabilities for photoacoustic, fluorescent and Raman imaging, CNTs are excellent diagnostic tools as well. Further, metallic nanoparticles, such as gold or silver nanoparticles, are combined with CNTs to create nanobiosensors to measure biological reactions. This review focuses on current knowledge about the theranostic potential of CNT, challenges associated with their large-scale production, their possible side effects and important parameters to consider when exploring their clinical usage.

Exploring the efficacy of tryptone-stabilized silver nanoparticles against respiratory tract infection-causing bacteria: a study on planktonic and biofilm forms.

Respiratory tract infections (RTIs) are a common cause of mortality and morbidity in the human population. The overuse of antibiotics to overcome such infections has led to antibiotic resistance. The emergence of multidrug resistant bacteria is necessitating the development of novel therapeutic techniques in order to avoid a major global clinical threat. Our study aims to investigate the potential of tryptone stabilised silver nanoparticles (Ts-AgNPs) on planktonic and biofilms produced byKlebsiella pneumoniae(K. pneumoniae)and Pseudomonas aeruginosa(P. aeruginosa). The MIC50of Ts-AgNPs was found to be as low as 1.7 µg ml-1and 2.7 µg ml-1forK. pneumoniae and P.aeruginosarespectively. Ts-AgNPs ability to alter redox environment by producing intracellular ROS, time-kill curves showing substantial decrease in the bacterial growth and significantly reduced colony forming units further validate its antimicrobial effect. The biofilm inhibition and eradication ability of Ts-AgNPs was found to be as high as 93% and 97% in both the tested organisms. A significant decrease in the eDNA and EPS quantity in Ts-AgNPs treated cells proved its ability to successfully distort the matrix and matured biofilms. Interestingly Ts-AgNPs also attenuated QS-induced virulence factors production. This study paves way to develop Ts-AgNPs as novel antibiotics against RTIs causing bacterial biofilms.

Mechanism of mitotic arrest induced by dolastatin 15 involves loss of tension across kinetochore pairs.

Dolastatin 15 (DL15) is a potent, tubulin-targeted, vinca-site binding, anticancer agent that induces mitotic arrest and inhibit cell proliferation in a variety of cell types. Several analogs of DL15, including LU 103793 and tasidotin, have been progressed to clinical trials for different types of cancer. DL15 has been known to interfere with cellular microtubules and purified tubulin in vitro. However, the molecular mechanism with which the peptide arrests cells in mitosis is poorly understood. This study reports a possible antimitotic mechanism of action of DL15. DL15 inhibited HeLa cell proliferation in a concentration-dependent manner with a half-maximal inhibitory concentration (IC50) of 2.8 ± 0.3 nM, induced mitotic arrest, disrupted cellular microtubules near its IC50 for cell proliferation, and inhibited the re-polymerization of cellular microtubules. By staining the centrosomes of DL15-treated cells with anti-γ tubulin antibodies, the study found a significant reduction in interpolar distances in mitotic HeLa cells, indicating a disruption in the normal assembly dynamics of the microtubules. The study further found that DL15 induced a loss of tension across the kinetochore pairs as indicated by a reduction in interkinetochore distance. In response to this loss of tension, the tension-sensing checkpoint protein BuBR1 accumulated at the kinetochores, promoting mitotic arrest. In vitro, DL15 promoted formation of curved and fragmented polymers of microtubule proteins and inhibited tubulin decay in a manner similar to vinca-site binding agents such as phomopsin A. Together, the data indicate that the mitotic arrest induced by DL15 involves a loss of tension across the kinetochore pairs due to disruption of normal assembly dynamics of microtubules.

Nano-ayurvedic medicine and its potential in cancer treatment.

Nano-ayurvedic medicine is an emerging field in which nanoparticles are functionalized with active principles of potent ayurvedic herbs to enhance their efficacy and target-specific delivery. Scientific advances in the past couple of decades have revealed the molecular mechanisms behind the anticancer potential of several ayurvedic herbs, attributed chiefly to their secondary metabolites including polyphenols and other active substances. With the advancement of nanotechnology, it has been established that size-, shape-, and surface-chemistry-optimized nanoparticles can be utilized as synergizing carriers for these phytochemicals. Nano-ayurvedic medicine utilizes herbs that are commonly used in Ayurveda to functionalize different nanoparticles and thereby enhance their potency and target specificity. Studies have shown that the active phytochemicals of such herbs can be coated onto the nanoparticles of different metals, such as gold, and that they work more efficiently than the free herbal extract, for example, in inhibiting cancer cell proliferation. Recently, an Ayurveda, Yoga & Naturopathy, Unani, Siddha and Homeopathy (AYUSH)-based clinical trial in humans indicated the anticancer potential of such formulations. Nano-ayurvedic medicine is emerging as a potential treatment option for hyperproliferative diseases.

Smart Delivery Systems Responsive to Cathepsin B Activity for Cancer Treatment.

Cathepsin B is a lysosomal cysteine protease, contributing to vital cellular homeostatic processes including protein turnover, macroautophagy of damaged organelles, antigen presentation, and in the extracellular space, it takes part in tissue remodeling, prohormone processing, and activation. However, aberrant overexpression of cathepsin B and its enzymatic activity is associated with different pathological conditions, including cancer. Cathepsin B overexpression in tumor tissues makes this enzyme an important target for smart delivery systems, responsive to the activity of this enzyme. The generation of technologies which therapeutic effect is activated as a result of cathepsin B cleavage provides an opportunity for tumor-targeted therapy and controlled drug release. In this review, we summarized different technologies designed to improve current cancer treatments responsive to the activity of this enzyme that were shown to play a key role in disease progression and response to the treatment.

Cooperative stabilization of microtubule dynamics by EB1 and CLIP-170 involves displacement of stably bound P(i) at microtubule ends.

End binding protein 1 (EB1) and cytoplasmic linker protein of 170 kDa (CLIP-170) are two well-studied microtubule plus-end-tracking proteins (+TIPs) that target growing microtubule plus ends in the form of comet tails and regulate microtubule dynamics. However, the mechanism by which they regulate microtubule dynamics is not well understood. Using full-length EB1 and a minimal functional fragment of CLIP-170 (ClipCG12), we found that EB1 and CLIP-170 cooperatively regulate microtubule dynamic instability at concentrations below which neither protein is effective. By use of small-angle X-ray scattering and analytical ultracentrifugation, we found that ClipCG12 adopts a largely extended conformation with two noninteracting CAP-Gly domains and that it formed a complex in solution with EB1. Using a reconstituted steady-state mammalian microtubule system, we found that at a low concentration of 250 nM, neither EB1 nor ClipCG12 individually modulated plus-end dynamic instability. Higher concentrations (up to 2 µM) of the two proteins individually did modulate dynamic instability, perhaps by a combination of effects at the tips and along the microtubule lengths. However, when low concentrations (250 nM) of EB1 and ClipCG12 were present together, the mixture modulated dynamic instability considerably. Using a pulsing strategy with [γ(32)P]GTP, we further found that unlike EB1 or ClipCG12 alone, the EB1-ClipCG12 mixture partially depleted the microtubule ends of stably bound (32)P(i). Together, our results suggest that EB1 and ClipCG12 act cooperatively to regulate microtubule dynamics. They further indicate that stabilization of microtubule plus ends by the EB1-ClipCG12 mixture may involve modification of an aspect of the stabilizing cap.

A molecular and structural mechanism for G protein-mediated microtubule destabilization.

The heterotrimeric, G protein-coupled receptor-associated G protein, Gα(s), binds tubulin with nanomolar affinity and disrupts microtubules in cells and in vitro. Here we determine that the activated form of Gα(s) binds tubulin with a K(D) of 100 nm, stimulates tubulin GTPase, and promotes microtubule dynamic instability. Moreover, the data reveal that the α3-ß5 region of Gα(s) is a functionally important motif in the Gα(s)-mediated microtubule destabilization. Indeed, peptides corresponding to that region of Gα(s) mimic Gα(s) protein in activating tubulin GTPase and increase microtubule dynamic instability. We have identified specific mutations in peptides or proteins that interfere with this process. The data allow for a model of the Gα(s)/tubulin interface in which Gα(s) binds to the microtubule plus-end and activates the intrinsic tubulin GTPase. This model illuminates both the role of tubulin as an "effector" (e.g. adenylyl cyclase) for Gα(s) and the role of Gα(s) as a GTPase activator for tubulin. Given the ability of Gα(s) to translocate intracellularly in response to agonist activation, Gα(s) may play a role in hormone- or neurotransmitter-induced regulation of cellular morphology.