ABSTRACT
The synergistic effects of tamoxifen on the sensitivity of MCF-7 cells to daunorubicin have been reported. Whether the effects of daunorubicin on MCF-7/adr cells can be improved by tamoxifen in liposomes and how tamoxifen changes daunorubicin's behavior in vivo remains unclear. The aim of this study was to investigate the effects of tamoxifen on the uptake and biodistribution of daunorubicin liposomes by breast-cancer-resistant MCF-7/adr cells in vitro and in vivo. The uptake of liposomes by MCF-7/adr cells in vitro studies was measured using flow cytometry and laser confocal microscopy. The biodistributions of carriers and free drugs were evaluated by DiR dye using in vivo imaging. Tamoxifen obviously enhanced the cellular uptake of liposomes by MCF-7/adr cells in time-dependent manners. According to the results from in vivo imaging analysis, the mean fluorescence intensity of DiR liposomes with tamoxifen in the tumor regions of MCF-7/adr tumor-bearing nude mice was much stronger than that of DiR liposomes alone (16,450 ± 1,331 versus 3,666 ± 321; n = 3). Pegylated liposomes elongated the existence of daunorubicin in the circulatory system and the enhanced permeability and retention effect enhanced its concentration in local tumor tissues, which may provide the precondition for tamoxifen further promoting the uptake by MCF-7/Adr cells in vivo. Using daunorubicin liposomes and tamoxifen together generates better biodistribution profiles in tumor tissue than using daunorubicin liposomes only, which contributes to improving the therapeutic effect of breast cancer treatment.
Subject(s)
Daunorubicin/administration & dosage , Daunorubicin/pharmacokinetics , Drug Carriers/pharmacokinetics , Liposomes/chemistry , Liposomes/pharmacokinetics , Tamoxifen/administration & dosage , Tamoxifen/pharmacology , Animals , Antineoplastic Agents/administration & dosage , Antineoplastic Agents/chemistry , Antineoplastic Agents/pharmacology , Cell Line, Tumor , Cell Proliferation/drug effects , Daunorubicin/chemistry , Daunorubicin/pharmacology , Dose-Response Relationship, Drug , Drug Carriers/administration & dosage , Drug Carriers/chemistry , Drug Screening Assays, Antitumor , Drug Stability , Female , Flow Cytometry , Humans , Liposomes/administration & dosage , Mice , Mice, Inbred BALB C , Mice, Nude , Microscopy, Confocal , Structure-Activity Relationship , Tamoxifen/pharmacokinetics , Tissue Distribution/drug effectsABSTRACT
BACKGROUND: Although there has been considerable progress made towards understanding the molecular mechanisms of bud dormancy, the roles of protein phosphorylation in the process of dormancy regulation in woody plants remain unclear. RESULTS: We used mass spectrometry combined with TiO2 phosphopeptide-enrichment strategies to investigate the phosphoproteome of dormant terminal buds (DTBs) in poplar (Populus simonii × P. nigra). There were 161 unique phosphorylated sites in 161 phosphopeptides from 151 proteins; 141 proteins have orthologs in Arabidopsis, and 10 proteins are unique to poplar. Only 34 sites in proteins in poplar did not match well with the equivalent phosphorylation sites of their orthologs in Arabidopsis, indicating that regulatory mechanisms are well conserved between poplar and Arabidopsis. Further functional classifications showed that most of these phosphoproteins were involved in binding and catalytic activity. Extraction of the phosphorylation motif using Motif-X indicated that proline-directed kinases are a major kinase group involved in protein phosphorylation in dormant poplar tissues. CONCLUSIONS: This study provides evidence about the significance of protein phosphorylation during dormancy, and will be useful for similar studies on other woody plants.
Subject(s)
Plant Proteins/chemistry , Plant Shoots/physiology , Populus/physiology , Proteome/analysis , Amino Acid Sequence , Arabidopsis/chemistry , Arabidopsis/physiology , Arabidopsis Proteins/chemistry , Conserved Sequence , Molecular Sequence Data , Phosphorylation , Plant Shoots/chemistry , Populus/chemistry , Protein Kinases/physiology , Signal TransductionABSTRACT
In this study we initiated a proteomic investigation of the maize thylakoid membrane by using a shotgun proteomic approach based on LC-MS(E). A total of 34 maize thylakoid membrane proteins were identified, the majority of which are primarily involved in photosynthesis, including the light-reaction and carbon assimilation. It is noteworthy that all of the core subunits of the Photosystem II were identified in our search. Proteins involved in other processes, such as iron storage, were also detected in our study. The quantity of each identified protein was also determined. Of interest, we discovered that the amount of the three ATP synthase subunits were not equivalent, suggesting that these proteins perform other functions in addition to ATP synthesis. To our knowledge this is the first extensive proteomic investigation of the maize thylakoid membrane, and will likely enable further study of maize photosynthesis and chloroplast development.
Subject(s)
Proteomics/methods , Thylakoids/metabolism , Zea mays/genetics , Chlorophyll/biosynthesis , Photosynthesis/genetics , Tandem Mass Spectrometry , Zea mays/metabolismABSTRACT
Accumulating evidence indicates that oxymatrine may exert protective effects on the cardiovascular system. This study was designed to evaluate the antiarrhythmic effects as well as the electrophysiological properties of oxymatrine. The antiarrhythmic activity of oxymatrine was observed in a rat model of arrhythmia induced by coronary ligation. Action potential duration (APD), L-type calcium current (I(Ca-L) ), transient outward potassium current (I(to) ) and inward rectifier potassium current (I(K1)) in rat ventricular myocytes were recorded by utilizing the whole cell patch-clamp technique. The results showed that administration of oxymatrine significantly delayed the onset of ventricular arrhythmia, decreased the duration of ventricular arrhythmia and reduced the arrhythmia score of arrhythmic rats. The beneficial effects of oxymatrine may be related to the shortening of APD through reduction of I(Ca-L) , enhancement of I(to) and inhibition of I(K1).
