Concurrently suppressing multidrug resistance and metastasis of breast cancer by co-delivery of paclitaxel and honokiol with pH-sensitive polymeric micelles.

To concurrently suppress multidrug resistance (MDR) and metastasis of breast cancer cells, paclitaxel (PTX) and honokiol (HNK) were coencapsulated into pH-sensitive polymeric micelles based on poly(2-ethyl-2-oxazoline)-poly(d,l-lactide) (PEOz-PLA). The physicochemical properties of dual drug-loaded PEOz-PLA micelles were characterized in size, drug loading and in vitro release. The efficiency of MDR reversal for the micelles was testified by synergetic enhancement of cytotoxicity and uptake by MCF-7/ADR cells. The flow cytometry and fluorescence polarization measurement results reinforced the conclusion that down-regulation of P-gp expression and increase of plasma membrane fluidity appeared to be possible mechanisms of MDR reversal by dual drug-loaded PEOz-PLA micelles. Further, the efficient inhibition of tumor metastasis by dual drug-loaded PEOz-PLA micelles was demonstrated by in vitro anti-invasion and anti-migration assessment in MDA-MB-231 cells and in vivo bioluminescence imaging in nude mice. The suppression of MDR and metastasis by the micelles was assigned to synergistic effects of pH-triggered drug release and HNK/PEOz-PLA-aroused P-gp inhibition, and pH-triggered drug release and PTX/HNK-aroused MMPs inhibition, respectively. In conclusion, our findings strengthen the usefulness of co-delivery of PTX and HNK by pH-responsive polymeric micelles for suppression of tumor MDR and metastasis. Multidrug resistance (MDR) and metastasis are considered to be two of the major barriers for successful chemotherapy. The combination of a chemotherapeutic drug with a modulator has emerged as a promising strategy for efficiently treating MDR cancer and preventing tumor metastasis. Herein, a dual drug (paclitaxel and honokiol)-loaded pH-sensitive polymeric micelle system based on PEOz-PLA was successfully fabricated to ensure that tumor MDR and metastasis could be concurrently suppressed, therefore achieving distinguishing endo/lysosomal pH from physiological pH by accelerating drug release and then enhancing the cytotoxicity of paclitaxel to drug-resistant tumor cells MCF-7/ADR by increasing cellular uptake of paclitaxel, preventing in vitro invasion and migration for MDA-MB-231 cells and in vivo metastasis in nude mice. Further, the mechanism of MDR reversal by dual drug-loaded PEOz-PLA micelles was elucidated to be down-regulation of P-gp expression and increase of plasma membrane fluidity of MCF-7/ADR cells. The present findings strengthen the usefulness of co-delivery of PTX and HNK by pH-responsive polymeric micelles for suppression of tumor MDR and metastasis.

Wang Z ，Li X ，Wang D ，Zou Y ，Qu X ，He C ，Deng Y ，Jin Y ，Zhou Y ，Zhou Y ，Liu Y ... -  《-》

Synergistically Enhanced Antimetastasis Effects by Honokiol-Loaded pH-Sensitive Polymer-Doxorubicin Conjugate Micelles.

Zou Y ，Zhou Y ，Jin Y ，He C ，Deng Y ，Han S ，Zhou C ，Li X ，Zhou Y ，Liu Y ... -  《-》

pH-responsive polymeric micelles based on poly(2-ethyl-2-oxazoline)-poly(D,L-lactide) for tumor-targeting and controlled delivery of doxorubicin and P-glycoprotein inhibitor.

The combination of a chemotherapeutic drug with a P-glycoprotein (P-gp) inhibitor has emerged as a promising strategy for treating multidrug resistance (MDR) cancer. To ensure that two drugs can be co-delivered to the tumor region and quickly released in tumor cells, tumor-targeted and pH-sensitive polymeric micelles were designed and prepared by combining cationic ring-opening polymerization of 2-ethyl-2-oxazoline (EOz) with anionic ring-opening polymerization of D,L-lactide (LA), and then encapsulating doxorubicin (DOX) and D-alpha-tocopheryl polyethylene glycol 1000 succinate (TPGS1000) into the micelles self-assembled by poly(2-ethyl-2-oxazoline)-poly(D,L-lactide) (PEOz-PLA) and DSPE-PEG-folate. PEOz-PLA exhibited a low critical micelle concentration and negligible cytotoxicity. The micelles enabled the rapid release of DOX when pH decreased from 7.4 to 5.0. The targeting ability of the micelles was demonstrated by in vitro flow cytometry in KBv cells and in vivo real time near-infrared fluorescence imaging in KBv tumor-bearing nude mice. The efficiency of MDR reversion for the micelles was testified by enhancement of intracellular DOX accumulation and cytotoxicity. The efficient drug delivery by the micelles was attributed to synergistic effects of folate-mediated targeting, pH-triggered drug release and TPGS1000-aroused P-gp inhibition. Therefore, the designed multifunctional polymeric micelles may have significant promise for therapeutic application of MDR cancer.

Zhao Y ，Zhou Y ，Wang D ，Gao Y ，Li J ，Ma S ，Zhao L ，Zhang C ，Liu Y ，Li X ... -  《-》

Systematic evaluation of multifunctional paclitaxel-loaded polymeric mixed micelles as a potential anticancer remedy to overcome multidrug resistance.

Multidrug resistance (MDR) of tumor cells is becoming the main reason for the failure of chemotherapy and P-glycoprotein (P-gp) mediated drug efflux has demonstrated to be the key factor for MDR. To address this issue, a novel pH-responsive mixed micelles drug delivery system composed of dextran-g-poly(lactide-co-glycolide)-g-histidine (HDP) and folate acid-D-α-tocopheryl polyethylene glycol 2000 (FA-TPGS2K) copolymers has been designed for the delivery of antitumor agent, paclitaxel (PTX) via FA-receptor mediated cell endocytosis, into PTX-resistant breast cancer MCF-7 cells (MCF-7/PTX). PTX-loaded FA-TPGS2K/HDP mixed micelles were characterized to have a small size distribution, high loading content and excellent pH-responsive drug release profiles. Compared with HDP micelles, FA-TPGS2K/HDP mixed micelles showed a higher cytotoxicity against MCF-7 and MCF-7/PTX cells due to the synergistic effect of FA-receptor mediated cell endocytosis, pH-responsive drug release and TPGS mediated P-gp inhibition. P-gp expression level, ATP content and mitochondrial membrane potential change have been measured, the results indicated blank FA-TPGS2K/HDP mixed micelles could inhibit the P-gp activity by reducing the mitochondrial membrane potential and depleting ATP content but not down-regulating the P-gp expression. In vivo antitumor activities demonstrated FA-TPGS2K/HDP mixed micelles could reach higher antitumor activity compared with HDP micelles for MCF-7/PTX tumor cells. Histological assay also indicated that FA-TPGS2K/HDP mixed micelles showed strongly apoptosis inducing effect, anti-proliferation effect and anti-angiogenesis effect. All these evidences demonstrated this pH-sensitive FA-TPGS2K/HDP micelle-based drug delivery system is a promising approach for overcoming MDR. In this work, a novel FA-TPGS2K copolymer has been synthesized and used it to construct mixed micelles with HDP copolymer to overcome MDR effect. Furthermore, a series in vitro and in vivo evaluations have been made, which supported enough evidences for the efficient delivery of antitumor drug to MDR cells.

Zhang J ，Zhao X ，Chen Q ，Yin X ，Xin X ，Li K ，Qiao M ，Hu H ，Chen D ，Zhao X ... -  《-》

Pluronic-based functional polymeric mixed micelles for co-delivery of doxorubicin and paclitaxel to multidrug resistant tumor.

Although doxorubicin (DOX) and paclitaxel (PTX) are widely used in clinic as chemotherapeutics, both drug substances are found to be glycoprotein P (P-gp) substrates which are liable to develop the multidrug resistance (MDR). Additionally, the use of single chemotherapeutic drug has known limitations such as high toxicity profile due to the relatively high doses and limited regimen of clinical application. To this end, Pluronic P105-DOX conjugate was successfully designed and developed which can be further used as a hydrophobic core to entrap another anti-cancer drug PTX with Pluronic F127 to form the dual drug-loaded mixed micelles (PF-DP) in our study, which would offer great advantages over conventional micelles, including easy fabrication, high loading capacity, and co-delivery of hydrophilic DOX and hydrophobic PTX to achieve synergistic effect of these two drug substances. Results showed that PF-DP possessed a good polydispersity and sustained release profile for both DOX and PTX in vitro. Studies on cellular uptake demonstrated both anti-cancer drugs in PF-DP can effectively accumulate in MDR cancer cells. Furthermore, in vitro cytotoxicity, cell apoptosis and cell cycle arrest studies indicated that PF-DP had better antitumor efficacy in MDR cancer cells compared to those of single-drug loaded micelles. It was also found that PF-DP can suppress the growth of tumor cells more efficiently than single drug formulations at the equivalent drug concentrations, suggesting synergistic effect could be achieved. More importantly, a much stronger antitumor efficacy in MCF-7/ADR tumor-bearing mice was observed in PF-DP group than that of combined administration of free DOX and PTX. Collectively, the dual drug-loaded Pluronic-based functional mixed micelles developed in this study might be a potential nano-drug delivery system for MDR cancer chemotherapy.

Chen Y ，Zhang W ，Huang Y ，Gao F ，Sha X ，Fang X ... -  《-》