ABSTRACT
The difference in pH between apical and basolateral side of intestinal epithelial and pH dependence character of the combination of FcRn (neonatal Fc receptor) and ligand might improve the delivery of hydrophobic drugs by facilitating the transcytosis of nanocarriers. Here we designed FcBP (IgG Fc domain-binding peptides) decorated coumarin 6 (C6) loaded poly(ethyl ethylene phosphate)-co-poly(ε-caprolactone) (PEG-PCL) micelles with different ligand densities to study the effect of pH and ligand density on the endocytosis and exocytosis process of micelles on human colon adenanocaricinoma cell lines (Caco-2). Active micelles with different ligand densities and passive micelles were prepared using the thin-film hydration method. The size of the micelles was characterized by dynamic light scattering analysis and the morphology was observed by transmission electron microscope. The endocytosis and exocytosis of the micelles at pH 7.4 and pH 6.0, as well as the effect of FcRn on the endocytosis, were investigated by flow cytometry. The results showed that the size of micelles was about 30 nm, which was not affected by FcBP decoration. We found that pH and ligand density could both influence the endocytosis. The uptake of active micelles was higher at pH 6.0 than at pH 7.4, and an optimal ligand density of endocytosis was appeared in both pH environment. Then we proved that FcBP decorated micelles could be endocytosed at pH 6.0 and exocytosed at pH 7.4, and the exocytosis process was also related to ligand density. Micelles with 10% ligand density had the largest exocytosis, showing the potentiality to deliver drugs through the intestinal epithelial. In addition, the competitive inhibition experiments illustrated that the interaction between FcRn and FcBP were essential to endocytosis. The results will enhance the understanding on the FcBP decorated PEG-PCL micelles for transmemberane drug delivery.
ABSTRACT
The integrity of poly(ethylene glycol)-co-poly(ε-caprolactone) (PEG-PCL) micelles transcellular transported across madin-darby canine kidney (MDCK) epithelial cells was investigated. Fluorescein isothiocyanate isomer I (FITC) was conjugated to PEG-PCL and the product PEG-PCL-FITC was identified by fluorescence spectra. Two micelles were prepared using the thin-film hydration method:3,3'-dioctadecyloxacarbocyanine perchlorate (DiO) and 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI) co-loaded PEG-PCL micelles (DiO-DiI-M), DiI loaded and PEG-PCL-FITC contained micelles (FITC-DiI-M). The size of the micelles was characterized by dynamic light scattering analysis using a Malvern Zetasizer Nano ZS and it turned out that the particle sizes of both micelles were about 30 nm with identical polydispersity index (PDI). The stability of the micelles in phosphate buffer saline (PBS) was monitored using fluorescence spectra and both micelles were stable within 4 h in PBS. The integrity of PEG-PCL micelles in the transcellular process across MDCK epithelial cell monolayer at 1 and 4 h was investigated using laser confocal scanning microscope and Förster resonance energy transfer (FRET) technology. The Person's coefficient and FRET efficiency of both Transwell layer and Receive layer were recorded. The results show that the FRET efficiency and Person's coefficient of the Receive layer was consistent with that of Transwell layer for both the micelles at 1 h, but decreased at 4 h and FITC-DiI-M decreased more significantly than DiO-DiI-M. The results indicated that the micelles could transport across the MDCK monolayer intactly at 1 h but some of them were disassembled during the 4 h transportation process.
ABSTRACT
<p><b>OBJECTIVE</b>To explore the synergetic effect of norcantharidin (NCTD) and adriamycin (ADR) on the proliferation and apoptosis of multiple myeloma (MM) cells.</p><p><b>METHODS</b>Human MM cell line U266 cells were treated with NCTD alone (10 µmol/L) or in combination with ADR (0.25 µmol/L). MTT and Annexin V/PI staining were used to determine cell viability and apoptosis. The protein expression of nuclear factor-κB P65 (NF-κB P65), phosphorylated NF-κB p65 (p-NF-κB p65), NF-κB P65 inhibitor IκBα, phosphorylated IκBα (p-IκBα), survivin, Bcl-2 and Bax were determined by Western blot. Immunohistochemistry was used to determine the expression of vascular endothelial growth factor (VEGF).</p><p><b>RESULTS</b>(1) NCTD potentiated the cytotoxicity and pro-apoptotic effects induced by ADR. The combination of NCTD and ADR had synergistic anti-proliferation effect. (2) Combination of ADR and NCTD downregulated the expression of nuclear NF-κB P65 and cytoplasm p-IκBα induced by ADR. The expression of nuclear NF-κB P65 and cytoplasm p-IκBα decreased from 2.08 ± 0.29 and 0.39 ± 0.07 to 0.48 ± 0.08 and 0.02 ± 0.01 respectively, while the expression of the cytoplasm NF-κB P65 and IκBα were unchanged in the ADR alone group and the combined group. (3) The expression of survivin and bcl-2 decreased from 0.31 ± 0.05 and 0.23 ± 0.05 to 0.03 ± 0.02 and 0.05 ± 0.02, while the expression of Bax increased from 0.46 ± 0.06 to 0.62 ± 0.08 respectively in ADR alone group and combined group. (4) The positive rate of VEGF in ADR group and combination group were (44.6 ± 4.4)% and (27.0 ± 2.1)% respectively, indicating that NCTD could potentiate the inhibition effect on VEGF induced by ADR.</p><p><b>CONCLUSIONS</b>The results suggest that NCTD can potentialize the chemosensitivity of multiple myeloma cells to ADR through regulating NF-κB/IκBα signaling pathway and NF-κB-regulated gene products including survivin, Bcl-2, Bax and VEGF.</p>