Weina Ma

Electrodeposited reduced graphene oxide incorporating polymerization of l-lysine on electrode surface and its application in simultaneous electrochemical determination of ascorbic acid, dopamine and uric acid

This paper demonstrates a novel strategy for the construction of a graphene hybrid composites film, which was fabricated by electrodeposited reduced graphene oxide (ERGO) incorporating polymerization of l-lysine (PLL) onto glassy carbon electrode (GCE). Here we show that graphene films can be prepared on electrodes directly from GO dispersions by one-step electrodeposition technique based on electropolymerized PLL as a positively charged polymer interface to adsorb negatively charged GO nanosheets through electrostatic attraction. The thickness of graphene film can be easily controlled by using the electrodeposition technique, a distinct advantage over previously developed methods. The electrochemically reduced process of GO and electropolymerization of l-lysine were investigated by cyclic voltammetry with a wide potential range. The surface morphology of the modified electrode was characterized by scanning electron microscopy. The ERGO/PLL/GCE shows conducive to electron transfer kinetics for Fe(CN)63-/Fe(CN)64- redox probes, compared with bare GCE, PLL/GCE and ERGO/GCE. The electrochemical behaviors of ascorbic acid (AA), dopamine (DA) and uric acid (UA) at ERGO/PLL/GCE were investigated by cyclic voltammetry, and the results suggest that the modified electrode exhibits enhanced electrocatalytic activity toward these important molecules. Under physiological condition and in the co-existence system of AA, DA and UA, the ERGO/PLL/GCE showed linear voltammetric responses in the concentration of 100μM-1200μM for AA, 2.0μM-60μM for DA and 20μM-200μM for UA, and with the detection limits (S/N=3) of 2.0μM, 0.10μM and 0.15μM for AA, DA and UA, respectively. The developed method has been applied to simultaneous determination of AA, DA and UA in human urine with satisfactory recoveries of 104.2%, 95.4% and 99.9%, respectively. This work demonstrates that the attractive features of ERGO/PLL provide promising applications in simultaneous determination of AA, DA and UA in physiological and pathological studies.

Berberine inhibits the proliferation and migration of breast cancer ZR-75-30 cells by targeting Ephrin-B2

BACKGROUND Berberine, a plant-derived compound isolated from Coptis chinensis used in traditional Chinese medicine, has been shown to possess anti-cancer properties. However, no study has shown that berberine could target ephrin-B2, which plays a critical role in cell proliferation and migration. PURPOSE The aim of this study is to investigate the effect of berberine on cancer cell growth and migration, through the regulation of ephrin-B2 and downstream signaling molecules. METHODS In this study, a high ephrin-B2-expressing cell membrane chromatography method was developed to investigate 48 crude extracts from traditional Chinese medicine that could act on ephrin-B2. Cell proliferative and wound-healing assays were used to study the effect of berberine on cancer cell growth and migration. The mechanism of berberine was investigated using western blot. RESULTS Berberine was isolated from C. chinensis extracts and showed activity on the HEK293/ephrin-B2 cell membrane chromatography column. Berberine showed a greater inhibitory effect in high-expressing ephrin-B2 cells (HEK293/ephrin-B2 cells) than in normal HEK293 cells, and decreased the expression of ephrin-B2 and its PDZ binding proteins, which indicates that ephrin-B2 is a target of berberine. Furthermore, berberine downregulates the phosphorylation of VEGFR2 and downstream signaling members (AKT and Erk1/2), which in turn downregulates the expression of MMP2 and MMP9. CONCLUSION The above data confirm the inhibitory effects of berberine on ZR-75-30 cell proliferation and cell migration. Overall, our studies demonstrate that berberine inhibits cell growth and migration by targeting ephrin-B2.

Determine equilibrium dissociation constant of drug-membrane receptor affinity using the cell membrane chromatography relative standard method

The equilibrium dissociation constant (KD) of drug-membrane receptor affinity is the basic parameter that reflects the strength of interaction. The cell membrane chromatography (CMC) method is an effective technique to study the characteristics of drug-membrane receptor affinity. In this study, the KD value of CMC relative standard method for the determination of drug-membrane receptor affinity was established to analyze the relative KD values of drugs binding to the membrane receptors (Epidermal growth factor receptor and angiotensin II receptor). The KD values obtained by the CMC relative standard method had a strong correlation with those obtained by the frontal analysis method. Additionally, the KD values obtained by CMC relative standard method correlated with pharmacological activity of the drug being evaluated. The CMC relative standard method is a convenient and effective method to evaluate drug-membrane receptor affinity.

Ta1722, an anti-angiogenesis inhibitor targeted on VEGFR-2 against human hepatoma.

In order to investigate the anti-angiogenesis potential and related mechanisms of Ta1722 (a novel taspine derivative compound), a series of experiments in vivo and in vitro were carried out. The proliferation on human cell lines of SMMC-7721, A549, MCF-7, Lovo, and ECV304 was examined by MTT. Angiogenesis inhibition was examined by chick embryo chorioallantoic membrane (CAM) angiogenesis and tube formation assays. Related angiogenesis proteins and their mRNA expression were determined by western blotting and RT-PCR. In addition, the SMMC-7721 nude mouse xenotransplant model was used to evaluate the inhibition of tumor growth. The results showed that Ta1722 inhibited cell proliferation, angiogenesis of CAM and tube formation, and downregulated related positive angiogenesis proteins. The above indicated Ta1722 could serve as a promising candidate of angiogenesis inhibitors by interrupting the VEGF/VEGFR-2 pathway.

Extracts of centipede Scolopendra subspinipes mutilans induce cell cycle arrest and apoptosis in A375 human melanoma cells

Extracts from the centipede Scolopendra genus, have been used in traditional medicine for the treatment of various diseases and have been found to exhibit anticancer activity in tumor cells. To investigate the potential and associated antitumor mechanism of alcohol extracts of the centipede Scolopendra subspinipes mutilans (AECS), cell viability, cell cycle and cell apoptosis were studied and the results revealed that AECS inhibits A375 cell proliferation in a dose- and time-dependent manner. In addition, AECS was found to arrest the cell cycle of A375 cells at the S phase, which was accompanied by a marked increase in the protein levels of cyclin E and a decrease in the protein levels of cyclin D1. In a cell culture system, AECS markedly induced the apoptosis of A375 cells, which was closely associated with the effects on the Bcl-2 family, whereby decreased Bcl-2 and increased Bak, Bax and Bad expression levels were observed. The underlying mechanism of AECS inhibiting A375 cell proliferation was associated with the induction of cell cycle arrest and apoptosis, indicating that AECS may present as a potential therapeutic agent for administration in human melanoma cancer intervention.

Interactions between histamine H1 receptor and its antagonists by using cell membrane chromatography method.

A high histamine H1 receptor (H1R) expression cell membrane chromatography (CMC) method was developed to investigate the affinity of ligands for H1R.

Overview of the detection methods for equilibrium dissociation constant K D of drug-receptor interaction

Drug-receptor interaction plays an important role in a series of biological effects, such as cell proliferation, immune response, tumor metastasis, and drug delivery. Therefore, the research on drug-receptor interaction is growing rapidly. The equilibrium dissociation constant (KD) is the basic parameter to evaluate the binding property of the drug-receptor. Thus, a variety of analytical methods have been established to determine the KD values, including radioligand binding assay, surface plasmon resonance method, fluorescence energy resonance transfer method, affinity chromatography, and isothermal titration calorimetry. With the invention and innovation of new technology and analysis method, there is a deep exploration and comprehension about drug-receptor interaction. This review discusses the different methods of determining the KD values, and analyzes the applicability and the characteristic of each analytical method. Conclusively, the aim is to provide the guidance for researchers to utilize the most appropriate analytical tool to determine the KD values.

Discovery and evaluation of triple inhibitors of VEGFR-2, TIE-2 and EphB4 as anti-angiogenic and anti-cancer agents

Receptor tyrosine kinases (RTKs), especially VEGFR-2, TIE-2, and EphB4, play a crucial role in both angiogenesis and tumorigenesis. Moreover, complexity and heterogeneity of angiogenesis make it difficult to treat such pathological traits with single-target agents. Herein, we developed two classes of multi-target RTK inhibitors (RTKIs) based on the highly conserved ATP-binding pocket of VEGFR-2/TIE-2/EphB4, using previously reported BPS-7 as a lead compound. These multi-target RTKIs exhibited considerable potential as novel anti-angiogenic and anticancer agents. Among them, QDAU5 displayed the most promising potency and selectivity. It significantly suppressed viability of EA.hy926 and proliferation of several cancer cells. Further investigations indicated that QDAU5 showed high affinity to VEGFR-2 and reduced the phosphorylation of VEGFR-2. We identified QDAU5 as a potent multiple RTKs inhibitor exhibiting prominent anti-angiogenic and anticancer potency both in vitro and in vivo. Moreover, quinazolin-4(3H)-one has been identified as an excellent hinge binding moiety for multi-target inhibitors of angiogenic VEGFR-2, Tie-2, and EphB4.

Investigation of the binding characteristics between ligands and epidermal growth factor receptor by cell membrane chromatography

The binding property between a ligand and its receptor is very important for numerous biological processes. In this study, we developed a high epidermal growth factor receptor (EGFR)‐expression cell membrane chromatography (CMC) method to investigate the binding characteristics between EGFR and the ligands gefitinib, erlotinib, canertinib, afatinib, and vandetanib. Competitive binding analysis using gefitinib as the marker was used to investigate the interactions that occurred at specific binding sites on EGFR. The ability of displacement was measured from the HEK293‐EGFR/CMC column on the binding sites occupied by gefitinib for these ligands, which revealed the following order: gefitinib (KD, 8.49 ± 0.11 × 10−7 M) > erlotinib (KD, 1.07 ± 0.02 × 10−6 M) > canertinib (KD, 1.41 ± 0.07 × 10−6 M) > afatinib (KD, 1.80 ± 0.12 × 10−6 M) > vandetanib (KD, 1.99 ± 0.03 × 10−6 M). This order corresponded with the values estimated by frontal displacement analysis and the scores obtained with molecular docking. Furthermore, thermodynamic analysis indicated that the hydrogen bond or Van der Waals force was the main interaction force in the process of EGFR binding to all 5 ligands. Overall, these results demonstrate that a CMC method could be an effective tool to investigate the binding characteristics between ligands and receptors.

Synergistic Effect of TPD7 and Berberine against Leukemia Jurkat Cell Growth through Regulating Ephrin-B2 Signaling

TPD7, a novel biphenyl urea taspine derivative, and berberine have presented inhibition on VEGFR2 that can be regulated by ephrin‐B2 reverse signaling through interactions with the PDZ domain. The purpose of this study is to investigate the inhibitory effect of the combination of TPD7 and berberine (TAB) on T‐cell acute lymphoblastic leukemia cell growth. TPD7 and berberine together synergistically inhibited the proliferation of Jurkat cells. Also, the combination of TAB induced G1‐phase cell‐cycle arrest by downregulating the level of cyclin D1, cyclin E, and CDC2. Furthermore, the combination of TAB significantly enhanced apoptosis in Jurkat cells, and the apoptosis most likely resulted from the modulation of the level of Bcl‐2 family members. Most importantly, the concomitant treatment simultaneously regulated the ephrin‐B2 and VEGFR2 signaling, as well as modulated the MEK/ERK and PTEN/PI3K/AKT/mTOR signaling. Therefore, the combination treatment of TAB may be a promising therapeutic method in treating T‐cell acute lymphoblastic leukemia. Copyright