Triple-negative breast cancer is the tumor that lacks expressions of estrogen receptor（ER）, progesterone receptor（PR） and human epidermal growth factor receptor-2（HER2）. A regular chemotherapy cannot eradicate triple-negative breast cancer. In the present study, we aimed to develop a combined use of daunorubicin and rofecoxib to treat triple-negative breast cancer, and reveal the underlying mechanisms. A gradient elution HPLC-UV method was developed for quantification, and the evaluations were performed on the triple-negative breast cancer MDA-MB-231 cells using a high content screening system. The results demonstrated that daunorubicin alone was insensitive to the triple negative breast cancer cells, while the combined use of daunorubicin and rofecoxib was able to effectively kill these triple-negative cancer cells, exhibiting a rofecoxib concentration-dependent manner. The mechanism revealed that the augmented anticancer efficacy was associated with direct killing effect, inducing apoptosis and inducing autophagy by the combination treatment. Besides, the apoptosis signaling pathways were correlated to a cascade of reactions by activating apoptotic enzyme caspase family and by suppressing anti-apoptotic gene expressed protein Bcl-2 family. In conclusion, this study provided a fundamental evidence for further developing the combined use of daunorubicin and rofecoxib formulation, hence offering a promising strategy for eradicating the triple negative breast cancer.
The present study aimed to investigate the targeting effect of H7K（R2）2-modified pH -sensitive liposomes on U87-MG cells. Using coumarin-6 as a fluorescence probe, we prepared H7K（R2）2-modified p H-sensitive liposomes（designated as coumarin-6-PSL-H7K（R2）2）. The flow cytometry assay was used to evaluate the effect of H7K（R2）2 proportions on the cellular uptake and endocytosis pathways of coumarin--6--PSL--H7K（R2）2 on U87-MG cells. The circular dichroism（CD） spectroscopy assay was used to investigate the secondary structures of H7K（R2）2 peptide at pH 7.4 and H 6.8, respectively. Our results indicated that the 2.5% proportion of H7K（R2）2 in the coumarin-6--PSL-H7K（R2）2 was superior to those of 1% and 3.5% of H7K（R2）2. The uptake of coumarin--6-PSL--H7K（R2）2 on U87--MG cells was not inhibited by filipin, M-β--CD or chlorpromazine. The secondary structure of H7K（R2）2 at pH 6.8 was mostly presented as β--turn. In conclusion, we suggested that the appropriate proportion of H7K（R2）2 in the H7K（R2）2--modified pH--sensitive liposomes could be set at 2.5%. The cellular uptake pathway for H7K（R2）2-modified pH--sensitive liposomes was via the cell penetrating capacity of H7K（R2）2 which responded to acidic condition. The secondary structure of H7K（R2）2 at pH 6.8, which was presented as the shape of hairpin, might be mainly responsible for its targeting and cell penetrating effect.
Theranostics, combining therapy and diagnosis, is an appealing approach for chemotherapy. In the present study, we selected paclitaxel （PTX） as a therapeutic agent, super-paramagnetic iron oxide nanoparticles （SPIO） as a diagnostic agent and sterically stabilized liposomes as a carrier to prepare theranostic liposomes. The SPIO were prepared and characterized. Moreover, the sterically stabilized liposomes containing PTX and SPIO （PTX/SPIO-SSL） were prepared. The characteristics of PTX/SPIO-SSL were investigated. The results indicated that prepared SPIO exhibited super-paramagnetic and could be used for MRI. The average particle size of PTX/SPIO-SSL was about 170 rim, with a polydispersity index （PDI） less than 0.3. The zeta potential of PTX/SPIO-SSL was negative. The PTX entrapment efficiency of PTX/SPIO-SSL was more than 98%. The TEM results indicated the spherical structure and dense SPIO content in PTX/SPIO-SSL. The in vitro release of PTX from PTX/SPIO-SSL and PTX-SSL was almost identical at both pH 6.8 and 7.4. In conclusion, the PTX/SPIO-SSL were prepared and characterized in vitro. The anti-tumor and diagnostic activity of PTX/SPIO-SSL should be investigated deeply in future study.
In the current study, we established and validated a simple and sensitive liquid chromatography-tandem mass spectrometric method for the determination of 21-hydroxy deflazacort in nude mice plasma, and such a method was applied to a pharmacokinetic study. Using betamethasone as the internal standard, the plasma samples were pre-treated by precipitation with acetonitrile and then analyzed on a reversed-phase C18 column （50 mm×2 mm, 5 μm） with a mobile phase consisting of acetonitrile and 4.0 mM ammonium formate （pH was adjusted to 3.5 with formic acid （40：60, v/v））. The analyte was detected by a triple quadrupole tandem mass spectrometer using electrospray, and multiple reaction monitoring was employed to select 21-hydroxy deflazacort at m/z 400.2/124.0 and betamethasone at m/z 393.3/147.0 in the positive ion mode. The calibration curves were linear （r〉0.99） over the range of 0.5~,00 ng/mL. The intra- and inter-day precisions and accuracies were 4.5%-10.1% and -1.7%-10.7% respectively. This method was successfully applied to a preclinical administered with a single oral dose of 4 mg/kg deflazacort, and its pharmacokinetic study of deflazacort on female nude mice pharmacokinetics was characterized by a two-compartment model with first-order absorption.
In the present study, a simple, rapid, and sensitive liquid chromatography-tandem mass spectrometric method for the determination of axitinib in nude mouse plasma was developed, validated, and applied to a pharmacokinetic study. Plasma samples were pre-treated by protein precipitation with acetonitrile spiked with erlotinib as an internal standard. The chromatographic separation was accomplished by using a reversed phase C18 column （50 mm×2 mm, 5 μm） with a simple mobile phase system composed of methanol and water （60：40, v/v） at an isocratic flow rate of 0.4 mL/min. The analyte was detected by a triple-quadrupole tandem mass spectrometer via electrospray ionization and multiple reaction monitoring was employed to select both axitinib and erlotinib in the positive ion mode. The calibration curves were linear （r〉0.99） ranging from 1 to 1000 ng/mL, and the lowest level of this range was the lower limit of quantification. The intra- and inter-day precision were 7.7%-12.0%, and the accuracies ranged from 88.6% to 110.4%. This method was successfully applied to a preclinical pharmacokinetic study on female nu/nu nude mice administrated with a single oral dose of axitinib at 120 mg/kg, and the pharmacokinetics was characterized by a one-compartment model with first-order absorption.
To ensure the delivery of antitumor drugs to tumor site and quick release in tumor cells, we designed and prepared pH-sensitive polymeric micelles by combining cationic ring-opening polymerization of 2-ethyl-2-oxazoline （EOz） with vitamin E succinate （VES）, and then encapsulating paclitaxel （PTX） into the micelles self-assembled by poly（2-ethyl-2-oxazoline）-vitamin E succinate （PEOz-VES）. The structure of the synthesized PEOz-VES was confirmed by ^1H NMR spectrum, and the molecular weight measured by GPC was 1212 g/mol. The pKa of PEOz-VES with a low critical micelle concentration of （5.84±0.02） mg/L was determined to be 6.01. The PTX-loaded PEOz-VES polymeric micelles prepared by film hydration method were characterized to have a nanoscaled size of about 30 nm in diameter, a positive Zeta potential of 4.86 mV and uniform spherical morphology by TEM observation. The drug loading content and encapsulation efficiency were （2.63±0.16）% and （84.1±3.38）%, respectively. The in vitro release behavior of PTX from PEOz-VES micelles in PBS displayed pH-dependent pattern and was gradually accelerated with decrease of pH value, implying that the micelles could distinguish endo/lysosomal pH and tumor extracellular pH from physiological pH by accelerating drug release. Therefore, the designed PEOz-VES micelles might have significant promise for anti-cancer drug delivery.
In this study, a sensitive and rapid LC-MS/MS method was developed and validated to determine dabigatran in plasma of beagle dogs after oral administration of dabigatran etexilate nanosuspension （DABE-NS）. The analytes （dabigatran） and sertraline hydrochloride （internal standard, IS） were separated on a Kromasil C18 column using gradient elution consisting of methanol and formate buffer at a flow rate of 0.4 mL/min in 20 min. Detection and quantitation were carded out by multiple reaction monitoring following the transitions： m/z 472.17→289.07 and 305.98→275.00 for dabigatran and IS at positive ion mode, respectively. The calibration curves were linear from 1.0 to 500.0 ng/mL for dabigatran with r = 0.9995. The accuracy of each analyte ranged from 94.8% to 107.1%, and the precision was within 6%. Besides, this method was successfully applied in the investigation of the pharmacokinetic profile of dabigatran in beagle dogs after oral administration of DABE-NS. The maximum concentration and the areas under curves of dabigatran for DABE-NS were significantly higher than those of control formulation, indicating improved oral absorption.
