Hypothesis of using albumin to improve drug efficacy in cancers accompanied by hypoalbuminemia.

A common problem in many cancers is the resistance of some patients to common drugs or relapse. Hypoalbuminemia has been reported in some of resistant cancer patients.This article evaluates the usefulness of albumin in the treatment of drug-resistant cancers with hypoalbuminemia based on available evidences.Rapid metabolism and drug excretion from the body is one of the causes of drug resistance. Albumin is the major plasma protein to which almost all drugs are bound. There is some evidence that increasing drug binding to albumin has beneficial effects on drug efficacy in some cancers and cancer cells. On the other hand, some reports have shown that cancer cells can use albumin as the energy and amino acid source.We have hypothesized that in this particular group of cancers, adding albumin to a treatment regimen could have a beneficial effect on drug efficacy and dosage. In fact, excess albumin can prevent rapid metabolism of drug by increasing the fraction of albumin-bound drug, and can increase drug delivery to cancer cells due to the absorption of drug-albumin complex by cancer cells.

Three Pt-Pt Complexes with Donor-acceptor Feature: Anticancer Activity, DNA Binding Studies and Molecular Docking Simulation.

BACKGROUND: Due to their unique properties and potential applications in variety of areas, recently, a special attention is given to the binuclear platinum (II) complexes. They reveal a highly tunable features upon the modification of their cyclometallating and bridging ligands. OBJECTIVE: The aim of this study was to evaluate the anticancer activity and DNA binding affinity of three binuclear platinum (II) complexes, including ht-[(p-FC6H4)Pt(µ-PN)(µ-NP)PtMe2](CF3CO2)(1), ht-[(p- MeC6H4)Pt(µ-PN)(µ-NP)Pt(p MeC6H4) Me] (CF3CO2)(2) and ht-[Pt2Me3(µ-PN)2](CF3CO2) (3). METHODS: MTT assay was performed to study the cell viability of Jurkat and MCF-7 lines against synthesized complexes, followed by apoptosis detection experiments. Several spectroscopic methods with molecular docking simulation were also used to investigate the detail of interaction of these platinum complexes with DNA. RESULTS: Cell viability assay demonstrated a notable level of cytotoxicity for the synthetic platinum complexes. Further studies proved that a pathway of cell signaling initiating the apoptosis might be activated by these complexes, particularly in the case of complexes 1 and 2. The results of both UV-visible and CD measurements showed the significant ability of these complexes to interact with DNA. While fluorescence data revealed that these complexes cannot enter DNA structure by intercalation, molecular docking assessment proved their DNA groove binding ability. CONCLUSION: The remarkable apoptosis inducing activity of the binuclear platinum complexes 1 and 2 and their considerable interaction with DNA suggest them as the potential antitumor medicines.

Gold-capped mesoporous silica nanoparticles as an excellent enzyme-responsive nanocarrier for controlled doxorubicin delivery.

Mesoporous silica nanoparticles (MSNs) have ideal characteristics as next generation of controlled drug delivery systems. In this study, a MSN-based nanocarrier was fabricated and gold nanoparticle (GNP)-biotin conjugates were successfully grafted onto the pore outlets of the prepared MSN. This bioconjugate served as a capping agent with a peptide-cleavable linker sensitive to matrix metalloproteinases (MMPs), which are overexpressed extracellular proteolytic enzymes in cancerous tissue. The prepared nanocarriers were fully characterised by scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption/desorption, Fourier transform infra-red spectroscopy (FTIR), dynamic light scattering (DLS) and thermo gravimetric analysis (TGA). In vitro release studies showed efficient capping of MSNs with gold gate and controlled release of Doxorubicin (DOX) in the presence of matrix metalloproteinase-2 (MMP-2) and acidic pH values. High DOX-loading capacity (21%) and encapsulation efficiency (95.5%) were achieved using fluorescence technique. DOX-loaded nanocarriers showed high cytocompatibility and could efficiently induce cell death and apoptosis in the MMP-2 overexpressed cell lines. Moreover, Haemolysis, platelet activation and inflammatory responses assessment approved excellent hemocompatibility and minimal side effects by encapsulation of DOX in MSNs carrier.

Stabilizing osmolytes' effects on the structure, stability and function of tc-tenecteplase: A one peptide bond digested form of tenecteplase.

Organic osmolytes, as major cellular compounds, cause protein stabilization in the native form. In the present study, the possible chaperone effects of the three naturally occurring osmolytes on the two-chain form of tenecteplase (tc-TNK), a recombinant, genetically engineered mutant tissue plasminogen activator, have been explored by using circular dichroism, steady-state fluorescence, UV-Visible spectroscopy, and in silico experiments. The tc-TNK is derived from the one-chain protein upon disruption of one peptide bond. Thermal denaturation experiments showed a slightly more stabilizing effect of the three co-solvents on the single-chain TNK (sc-TNK) in comparison to that on tc-TNK. Unlike single-chain tenecteplase, the two-chain form undergoes reversible denaturation which is somehow perturbed in some cases as the result of the presence of osmolytes. Very minor changes in the secondary structure and the tertiary structure were observed. The molecular dynamics simulations and comparative structural analysis of catalytic domain of the protein in the single-chain and two-chain forms in pure water, mannitol/water, trehalose/water, and sucrose/water showed that while the stabilizing effect of the three osmolytes on tc-TNK might be induced by preferential accumulation of these molecules around the nonpolar and aromatic residues, that is to say, fewer water-hydrophobic residues' interactions in tc-TNK, sc-TNK is stabilized by preferential exclusion effect.

Natural Polyphenols Selectively Inhibit ß-Carbonic Anhydrase from the Dandruff-Producing Fungus Malassezia globosa: Activity and Modeling Studies.

Around 50 % of the worldwide population is affected by dandruff, which is triggered by a variety of factors. The yeast Malassezia globosa has been labeled as the most probable causative agent for the onset of dandruff. The ß-carbonic anhydrase (CA) of MgCA was recently validated as an anti-dandruff target, with its inhibition being responsible for in vivo growth defects in the fungus. As classical CA inhibitors of the sulfonamide type give rise to permeability problems through biological membranes, finding non-sulfonamide alternatives for MgCA inhibition is of considerable interest in the cosmetic field. We recently screened a large library of human (h) CA inhibitors for MgCA inhibition, including different chemotypes, such as monothiocarbamates, dithiocarbamates, phenols, and benzoxaboroles. Herein, we expanded the research toward new MgCA inhibitors by considering a set of natural polyphenols (including flavones, flavonols, flavanones, flavanols, isoflavones, and depsides) that exhibited MgCA inhibitory activity in the micromolar range, as well as selectivity for the fungal isozyme over off-target human isoforms. The binding mode of representative derivatives within the MgCA catalytic cleft was investigated by docking studies using a homology-built model.

Selectivity of major isoquinoline alkaloids from Chelidonium majus towards telomeric G-quadruplex: A study using a transition-FRET (t-FRET) assay.

BACKGROUND: Natural bioproducts are invaluable resources in drug discovery. Isoquinoline alkaloids of Chelidonium majus constitute a structurally diverse family of natural products that are of great interest, one of them being their selectivity for human telomeric G-quadruplex structure and telomerase inhibition. METHODS: The study focuses on the mechanism of telomerase inhibition by stabilization of telomeric G-quadruplex structures by berberine, chelerythrine, chelidonine, sanguinarine and papaverine. Telomerase activity and mRNA levels of hTERT were estimated using quantitative telomere repeat amplification protocol (q-TRAP) and qPCR, in MCF-7 cells treated with different groups of alkaloids. The selectivity of the main isoquinoline alkaloids of Chelidonium majus towards telomeric G-quadruplex forming sequences were explored using a sensitive modified thermal FRET-melting measurement in the presence of the complementary oligonucleotide CT22. We assessed and monitored G-quadruplex topologies using circular dichroism (CD) methods, and compared spectra to previously well-characterized motifs, either alone or in the presence of the alkaloids. Molecular modeling was performed to rationalize ligand binding to the G-quadruplex structure. RESULTS: The results highlight strong inhibitory effects of chelerythrine, sanguinarine and berberine on telomerase activity, most likely through substrate sequestration. These isoquinoline alkaloids interacted strongly with telomeric sequence G-quadruplex. In comparison, chelidonine and papaverine had no significant interaction with the telomeric quadruplex, while they strongly inhibited telomerase at transcription level of hTERT. Altogether, all of the studied alkaloids showed various levels and mechanisms of telomerase inhibition. CONCLUSIONS: We report on a comparative study of anti-telomerase activity of the isoquinoline alkaloids of Chelidonium majus. Chelerythrine was most effective in inhibiting telomerase activity by substrate sequesteration through G-quadruplex stabilization. GENERAL SIGNIFICANCE: Understanding structural and molecular mechanisms of anti-cancer agents can help in developing new and more potent drugs with fewer side effects. Isoquinolines are the most biologically active agents from Chelidonium majus, which have shown to be telomeric G-quadruplex stabilizers and potent telomerase inhibitors.

Unfolding of insulin at the surface of ZnO quantum dots.

ZnO quantum dots (QDs) have been used in many biomedical applications such as bioimaging, cancer treatments and etc. Crystallinity, particle size, optical absorption and photoluminescence spectra of ZnO QDs were analyzed by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-vis absorption spectroscopy and fluorescence spectroscopy respectively. Interaction of ZnO QDs with insulin was investigated by fluorescence quenching, circular dichroism (CD), isothermal titration calorimetry (ITC) and thermal aggregation tests. The fluorescence quenching results showed a static type quenching along with red shift in synchronize fluorescence (a sign of protein unfolding). CD spectroscopy results also confirmed this unfolding and show a reduction in alpha helices content of insulin in contact with ZnO QDs and their conversion to random coils. According to ITC results, the ΔG, ΔH and binding constant of this interaction are -32.35 kJ/mol, -43.21 kJ/mol and 4.69 × 10(5) M(-1), respectively. Thermal aggregation test showed fast aggregation of insulin in the presence of ZnO QDs. Therefore in biological application of ZnO QDs such as bioimaging, presence of such QDs in vicinity of insulin could unfold this protein.

Chitosan-coated superparamagnetic iron oxide nanoparticles for doxorubicin delivery: synthesis and anticancer effect against human ovarian cancer cells.

Doxorubicin-loaded chitosan-coated superparamagnetic iron oxide nanoparticles (Fe3 O4 ; SPIO-NPs) were prepared by coprecipitation and emulsification cross-linking method and uniform NPs with an average particle size of 82 nm, with high encapsulation efficiencies, were obtained. The drug-loading efficiency of doxorubicin (3.2 mg/mg NPs) showed better results for the chitosan-loaded SPIO-NPs as compared to the bare ones (0.5 mg/mg; p < 0.05). The incubation of A2780 and OVCAR-3 human ovarian cancer cells with doxorubicin-loaded and doxorubicin-loaded chitosan-coated SPIO-NPs, for 24, 48, 72, 96, and 120 h, showed significant IC50 (2.0 ± 0.6 and 7.1 ± 2.7 mm doxorubicin) and IC90 (4.0 ± 9.2 and 10 ± 0.5 mm doxorubicin), respectively, after 96 h of incubation. While, 95% and 98% growth inhibition was seen in A2780 and OVCAR-3 cells after the 96-h exposure to the doxorubicin-chitosan-SPIO-NPs (p < 0.05). A 5-day (120 h) incubation with doxorubicin-chitosan-SPIO-NPs showed that A2780 and OVCAR-3 cells were able to uptake 120 and 110 pg iron/cell, respectively, when treated with doxorubicin-chitosan-SPIO-NPs for 72 h (p < 0.05).

Structure and stability analysis of cytotoxic complex of camel α-lactalbumin and unsaturated fatty acids produced at high temperature.

α-Lactalbumin α-La), together with oleic acid can be converted to a complex, which kills tumor cells selectively. Cytotoxic α-La -oleic acid and α-La -linoleic acid complexes were generated by adding fatty acid to camel holo α-La at 60 ° C (referred to as La-OA-60 and La-LA-60 state, respectively). Structural properties of these complexes were studied and compared to the camel α-La. The experimental results show that linoleic acid induces α-La partial unfolding but oleic acid does not change the protein structure significantly. Also the stability of La-OA-60 and La-LA-60 toward thermal denaturation was measured. The order of temperature at the transition midpoint is as follows: La-LA-60 < La-OA-60 < α-La. La-OA-60 complex inhibited tubulin polymerization in vitro. Although the structures of La-OA-60 and La-LA-60 were different, these two complexes had similar cytotoxic effect to DU145 human prostate cancer cells. Samples of La-OA-60 that have been renatured after denaturation lost the specific biological activity toward tumor cells.

Investigation of effects of newly synthesized Pt(II) complex against human serum albumin and leukemia cell line of K562.

The biological evaluation of a new synthesized Pt(II)-complex, 2,2'-bipyridin Butylglycinato Pt(II) nitrate, an anti-tumor component, was studied at different temperatures by fluorescence and far UV circular dichroism (CD) spectroscopic methods. Human serum albumin (HSA) and human tumor cell line K562 were as targets. The Pt(II)-complex has a strong ability to quench the intrinsic fluorescence of HSA. Binding and thermodynamic parameters of the interaction were calculated by fluorescence quenching method. Far-UV-CD results showed that Pt(II)-complex induced increasing in content of α helical structure of the protein and stabilized it. The 50% cytotoxic concentration (Cc(50)) of complex was determined using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay at different incubation times. Also, fluorescence staining with DAPI (4,6-diamidino-2-phenylindole) revealed some typical nuclear changes, which are characteristic of apoptosis. Above results suggest that Pt (II) complex is a promising anti-proliferative agent and should execute its biological effects by inducing apoptosis.

Effects of surfactant, salt and solvent on the structure and activity of adenosine deaminase: molecular dynamic and spectrophotometric studies.

Effects of sodium dodecyl sulfate, dodecyltrimethylammonium bromide, sodium chloride, sodium sulfate, methanol and ethanol, on the structure and activity of adenosine deaminase (ADA) were investigated by UV-Vis, circular dichroism spectrophotometry and molecular dynamics (MDs) studies. Relative activity, experimental and computational helix content, total accessible surface area (ASA) and exposed charged surface area (ECSA) were obtained. The relative activity of ADA in the absence and the presence of denaturants were compared with structural results. It was shown that an increase in the surface area and a decrease in the amount of helicity are associated with a decrease in the activity of ADA.

The mechanisms underlying the effect of alpha-cyclodextrin on the aggregation and stability of alcohol dehydrogenase.

High concentrations of proteins and enzymes have to be stored for extended periods of time. Under such conditions, at least three major factors contribute to aggregation and loss of protein function: hydrophobicity, propensity to form non-native beta-sheet structure and net charge of the polypeptide chain. Here we evaluate these thermal aggregation factors for horse liver ADH (alcohol dehydrogenase) and the effect of alpha-CyD (alpha-cyclodextrin) on the ADH aggregation, by using fluorescence, CD, UV-visible spectrophotometry, the DLS (dynamic light scattering) technique and the enzymatic activity assay. In addition, we propose the relative importance of the hydrophobic effect on the ADH aggregation. Although ADH readily forms aggregates at higher temperatures, alpha-CyD effectively diminishes this phenomenon. This reduction can be attributed to the prevention of the appearance of larger-size aggregated molecules and also to the higher homogeneity of the small nuclei under the alpha-CyD effect. The observed re-aggregation upon the addition of alpha-CyD/phenylalanine can be attributed to the competition binding of phenylalanine to the internal hydrophobic cavity of alpha-CyD. This signifies that aromatic amino acids are important regional components of the residual structure that may form nuclei for aggregation. The results of dynode voltage changes indicate that the thermal unfolding of ADH is accompanied by protein aggregation, which subsequently leads to irreversible thermal unfolding. Moreover, alpha-CyD causes thermal stabilization and delays the onset of secondary structural unfolding and aggregation by approx. 10 degrees C and the midpoint ('melting') temperatures (T(m)) by more than 5 degrees C. Furthermore, alpha-CyD diminishes the deactivation of the enzyme, decreasing the deactivation constant by more than 50%, and clearly reveals the stabilization of the enzyme not only structurally but also kinetically at higher temperatures.

Kinetic, thermodynamic and statistical studies on the inhibition of adenosine deaminase by aspirin and diclofenac.

The kinetic and thermodynamic effects of aspirin and diclofenac on the activity of adenosine deaminase (ADA) were studied in 50 mM phosphate buffer pH = 7.5 at 27 and 37 degrees C, using UV-Vis spectrophotometry and isothermal titration calorimetry (ITC). Aspirin exhibits competitive inhibition at 27 and 37 degrees C and the inhibition constants are 42.8 and 96.8 microM respectively, using spectrophotometry. Diclofenac shows competitive behavior at 27 degrees C and uncompetitive at 37 degrees C with inhibition constants of 56.4 and 30.0 microM, at respectively. The binding constant and enthalpy of binding, at 27 degrees C are 45 microM, - 64.5 kJ/mol and 61 microM, - 34.5 kJ/mol for aspirin and diclofenac. Thermodynamic data revealed that the binding process for these ADA inhibitors is enthalpy driven. QSAR studies by principal component analysis implemented in SPSS show that the large, polar, planar, and aromatic nucleoside and small, aromatic and polar non-nucleoside molecules have lower inhibition constants.

Design, synthesis, and biological evaluation of a cephalosporin-monohydroguaiaretic acid prodrug activated by a monoclonal antibody-beta-lactamase conjugate.

A novel cephalosporin derivative of monohydroguaiaretic acid (cephem-M(3)N, 7) was synthesized and found to possess anticancer activity against human leukemia (K562), breast carcinoma (MCF7), human lung cancer (A549), human colon cancer (Colo205) and pancreatic cancer cells (Capan2 and MiaPaCa2). A tumor targeting fusion protein (dsFv3-beta-lactamase) was also used in conjunction with cephem-based M(3)N 7 and its potency toward K562, MCF7, A549, Colo205, Capan2, and MiaPaCa2 was found to approach that of the free M(3)N (4). In the presence of dsFv3-beta-lactamase, tumor cells were found to be much more susceptible to conjugate 7 than normal human embryonic lung (HEL) cells and normal fibroblasts (Hef522). These notions provide a new approach to the use of nordihydroguaiaretic acid (NDGA) and its derivatives for antitumor therapy.