The osteogenic niche-targeted arsenic nanoparticles prevent colonization of disseminated breast tumor cells in the bone.

Up to 70% of patients with late-stage breast cancer have bone metastasis. Current treatment regimens for breast cancer bone metastasis are palliative with no therapeutic cure. Disseminated tumor cells (DTCs) colonize inside the osteogenic niches in the early stage of bone metastasis. Drug delivery into osteogenic niches to inhibit DTC colonization can prevent bone metastasis from entering its late stage and therefore cure bone metastasis. Here, we constructed a 50% DSS6 peptide conjugated nanoparticle to target the osteogenic niche. The osteogenic niche was always located at the endosteum with immature hydroxyapatite. Arsenic-manganese nanocrystals (around 14 nm) were loaded in osteogenic niche-targeted PEG-PLGA nanoparticles with an acidic environment-triggered arsenic release. Arsenic formulations greatly reduced 4T1 cell adhesion to mesenchymal stem cells (MSCs)/preosteoblasts (pre-OBs) and osteogenic differentiation of osteoblastic cells. Arsenic formulations also prevented tumor cell colonization and dormancy via altering the direct interaction between 4T1 cells and MSCs/pre-OBs. The chemotactic migration of 4T1 cells toward osteogenic cells was blocked by arsenic in mimic 3D osteogenic niche. Systemic administration of osteogenic niche-targeted arsenic nanoparticles significantly extended the survival of mice with 4T1 syngeneic bone metastasis. Our findings provide an effective approach for osteogenic niche-specific drug delivery and suggest that bone metastasis can be effectively inhibited by blockage of tumor cell colonization in the bone microenvironment.

Docetaxel-Loaded Chitosan-Cholesterol Conjugate-Based Self-Assembled Nanoparticles for Overcoming Multidrug Resistance in Cancer Cells.

Cholesteryl hemisuccinate (CHS)-conjugated chitosan (CS)-based self-assembled nanoparticles (NPs) were developed for enhancing the intracellular uptake of docetaxel in multidrug resistance (MDR)-acquired cancer cells. CHS-CS was successfully synthesized and self-aggregation, particle size, zeta potential, drug entrapment efficiency, and in vitro drug release of docetaxel-loaded CHS-CS NPs were tested. The optimized NPs had a mean hydrodynamic diameter of 303 nm, positive zeta potential of 21.3 mV, and spherical shape. The in vitro release of docetaxel from the optimized CHS-CS NPs in different pH medium (pH 6.0 and 7.4) revealed that the release was improved in a more acidic condition (pH 6.0), representing a tumor cell's environment. The superior MDR-overcoming effect of docetaxel-loaded CHS-CS NPs, compared with docetaxel solution, was verified in anti-proliferation and cellular accumulation studies in MDR-acquired KBV20C cells. Thus, CHS-CS NPs could be potentially used for overcoming the MDR effect in anticancer drug delivery.

Dual oligopeptides modification mediates arsenic trioxide containing nanoparticles to eliminate primitive chronic myeloid leukemia cells inside bone marrow niches.

Chronic myeloid leukemia (CML) is one type of hematopoietic stem cell diseases. Although BCR-ABL1 tyrosine kinase inhibitors are remarkably effective in inducing remission in chronic phase patients, they are not curative in a majority of patients due to their failure to eradicate residual CML stem/progenitor cells, which reside in bone marrow niches. Here, we presented novel dual oligopeptides-conjugated nanoparticles and demonstrated their effective delivery of arsenic trioxide in bone marrow niches for the elimination of primitive CML cells. We encapsulated As-Ni transitional metal compounds into polymeric nanoparticles based on the reverse micelle rationale. The loading density and stability of arsenic trioxide in nanoparticles were improved. In vitro experiments demonstrated that dual oligopeptides conjugated nanoparticles could deliver arsenic trioxide into bone marrow niches including endosteal niches and vascular niches. The colony-forming activity of CML cells was remarkably restrained in the presence of metaphyseal bone fragments pre-incubated with bone marrow niche targeted arsenic nanoparticles. The in vitro vascular niche model suggested that CML cell proliferation was also successfully inhibited through a tight contact with HUVECs, which were pre-treated using niche-targeted arsenic nanoparticles. This bone marrow niche targeted delivery strategy has a potential usage for the treatment of CML and other malignant hematologic disorders originated from the bone marrow.

Effect of ß-elemene on the kinetics of intracellular transport of d-luciferin potassium salt (ABC substrate) in doxorubicin-resistant breast cancer cells and the associated molecular mechanism.

In order to explore the mechanism of the reversing multidrug resistance (MDR) phenotypes by ß-elemene (ß-ELE) in doxorubicin (DOX)-resistant breast cancer cells (MCF-7/DOX), both the functionality and quantity of the ABC transporters in MCF-7/DOX were studied. Bioluminescence imaging (BLI) was used to study the efflux of d-luciferin potassium salt, the substrate of ATP-binding cassette transporters (ABC transporters), in MCF-7/DOX cells treated by ß-ELE. At the same time three major ABC transport proteins and genes-related MDR, P-glycoprotein (P-gp, ABCB1) and multidrug resistance-associated protein 1 (MRP, ABCC1) as well as breast cancer resistance protein (BCRP, ABCG2) were analyzed by q-PCR and Western blot. To investigate the efflux functionality of ABC transporters, MCF-7/DOXFluc cell line with stably-overexpressed luciferase was established. BLI was then used to real-time monitor the efflux kinetics of d-luciferin potassium salt before and after MCF-7/DOXFluc cells being treated with ß-ELE or not. The results showed that the efflux of d-luciferin potassium salt from MCF-7/DOXFluc was lessened when pretreated with ß-ELE, which means that ß-ELE may dampen the functionality of ABC transporters, thus decrease the efflux of d-fluorescein potassium or other chemotherapies which also serve as the substrates of ABC transporters. As the effect of ß-ELE on the expression of ABC transporters, the results of q-PCR and Western blot showed that gene and protein expression of ABC transporters such as P-gp, MRP, and BCRP were down-regulated after the treatment of ß-ELE. To verify the efficacy of ß-ELE on reversing MDR, MCF-7/DOX cells were treated with the combination of DOX and ß-ELE. MTT assay showed that ß-ELE increased the inhibitory effect of DOX on the proliferation of MCF-7/DOX, and the IC50 of the combination group was much lower than that of the single DOX or ß-ELE treatment. In all, ß-ELE may reverse MDR through the substrates of ABC transporters by two ways, to lessen the ABC protein efflux by weakening their functionality, or to reduce the quantity of ABC gene and protein expression.

Targeted drug delivery for tumor therapy inside the bone marrow.

Bone marrow is the primary hematopoietic organ, which is involved in multiple malignant diseases including acute and chronic leukemia, multiple myeloma, myelodysplastic syndromes, and bone metastases from solid tumors. These malignancies affect normal homeostasis and reshape the bone marrow microenvironment. There are limited treatment options for them because of their inevitable aggravation. The current systemic administration of anticancer agents is difficult to achieve ideal therapeutic dose to suppress tumor growth at bone marrow diseased sites, and is always associated with a high incidence of relapse and severe side effects. The limitations of current treatments urge scientists to develop bone marrow targeted drug delivery systems intended for the treatment of diseased bone marrow, which can improve the efficacy of therapeutic agents and reduce their dose-limiting systemic side effects on healthy tissues. In this review we first present the current opinions on bone marrow vasculature, as well as the molecular and structural interactions between tumor cells and the diseased bone marrow. In the second part, we highlight the different design rationales and strategies of bone marrow delivery systems and their therapeutic applications for the treatment of malignancies inside the bone marrow.

Preparation of mixed monoterpenes edge activated PEGylated transfersomes to improve the in vivo transdermal delivery efficiency of sinomenine hydrochloride.

Surfactants generally have been used as edge activators of transfersomes. However, surfactants edge activated transfersomes frequently lead to cutaneous irritation, skin lipid loss and other side effects after dermal administration. In this study, mixed monoterpenes edge activated PEGylated transfersomes (MMPTs) were prepared by ethanol injection process with sinomenine hydrochloride as a model drug. The formulation of MMPTs was optimized by an orthogonal design. We investigated skin permeation/deposition characteristics and pharmacokinetics of sinomenine hydrochloride loaded in MMPTs by comparing with liposomes using in vitro skin tests and in vivo cutaneous microdialysis. In in vitro study, the accumulative skin permeated quantity (ASPQ) and skin permeation rate (SPR) of simonenine (SIN) in the optimized MMPTs were prominently higher than that in the other MMPTs. The optimized MMPTs had a SIN ASPQ of over three times of SIN ASPQ in the liposomes and much larger SPR of SIN compared with the latter. In contrast, the drug deposition of the optimized MMPTs in the stratum corneum was much less than that of the conventional liposomes. It was noteworthy that the drug deposition curve in the whole skin (stratum corneum-stripped skin, either) for the optimized MMPTs increased initially and then decreased with an obvious peak deposition amount at 12h, while, a relatively steady curve was observed for the liposomes. In in vivo cutaneous pharmacokinetic study, the steady state concentration (Css) and the area under the curve (AUC0→t) of SIN from the optimized MMPTs was 8.7 and 8.2 folds higher than those from the liposomes, respectively. Moreover, the MRT0-inf of SIN from optimal MMPTs got shorter than that from the liposomes. It can be concluded that the optimized MMPTs obviously enhance the percutaneous absorption of sinomenine.

Codelivery of Ponatinib and SAR302503 by Active Bone-Targeted Polymeric Micelles for the Treatment of Therapy-Resistant Chronic Myeloid Leukemia.

Point mutations in the BCR-ABL1 domain and primitive chronic myelogenous leukemia (CML) cells existing in the bone marrow environment insensitive to tyrosine kinase inhibitors (TKIs) have become two major challenges in the CML therapy. In this study, combined TKI ponatinib and JAK2 inhibitor SAR302503 short-term treatment effectively suppressed growth and promoted apoptosis of BaF3/T315I cells in cytokine-containing medium in vitro. SAR302503 prevented cytokine-dependent resistance to ponatinib via inhibition of JAK2/STAT5 phosphorylation. Codelivery of ponatinib and SAR302503 by active bone-targeted polymeric micellar formulation greatly increased the drug accumulation in medullary cavity. The therapeutic efficacy of bone-targeted formulation was demonstrated in BaF3/T315I cells inoculated murine model with no dose-limited toxicity detectable in health mice. Thus, the intravenous injectable bone-homing ponatinib and SAR302503 micellar formulation represents a promising strategy for the treatment of therapy-resistant CML.

The effects of mixed MPEG-PLA/Pluronic copolymer micelles on the bioavailability and multidrug resistance of docetaxel.

A mixed micelle that comprised of MPEG-PLA (MPP) and Pluronic copolymers was developed for enhanced bioavailability and to overcome multidrug resistance of docetaxel in cancer therapy. The mixed micelles that sufficiently solubilized docetaxel were evaluated for the effect of Pluronic copolymers weight ratio on the mixed micelles with respect to drug loading and drug release. In vitro, cell viability and cytotoxicity studies in KB and KBv cells revealed that the mixed micellar formulations were more potent than the commercial docetaxel formulation (Taxotere). In vivo pharmacokinetics study in rats showed that the mixed micelles significantly enhanced the bioavailability of docetaxel (3.6 fold) than Taxotere. Moreover, antitumor activity assessed in KBv cancer xenograft BALB/C nude mice models showed that the mixed micelles significantly reduced the tumor size than the control (Taxotere). Clear differences in the intracellular uptake of docetaxel between MPP and mixed micelles were observed using confocal laser scanning microscopy. This study presents not only a new micelle structure for a diblock-triblock copolymer system, but also a method for enhanced bioavailability of docetaxel and to overcome some of the limitations on its multidrug resistance in cancer therapy.

Docetaxel microemulsion for enhanced oral bioavailability: preparation and in vitro and in vivo evaluation.

A microemulsion system of docetaxel was prepared and evaluated for its solubilization capacity and oral bioavailability improvement. Based on a solubility study and pseudo ternary phase diagrams, microemulsions of about 30 nm in mean diameter were formulated with improved solubilization capacity towards the hydrophobic drug, docetaxel. The o/w microemulsion formulation (M-3) composed of Capryol 90 (oil), Cremophor EL (surfactant) and Transcutol (co-surfactant) enhanced the solubility of docetaxel up to 30 mg/mL, which maintained solubilization capacity for 24 h even after it was diluted 20 times with normal saline. The three formulations did not show significant difference in the in vitro lipid digestion study. Both the ultrafiltration and dialysis studies revealed that the release of 80% of docetaxel was released from the microemulsions within 12 h in vitro. Compared to the commercial product Taxotere (0.025 microg/cm(2)), the apical to basolateral transport of docetaxel across the Caco-2 cell monolayer from the M-3 formulation (Capryol 90/Cremophor EL/Transcutol=29.4:24.9:12.4, w/w) was significantly improved (0.624 microg/cm(2), p < 0.01). Moreover, the oral bioavailability of the M-3 formulation in rats (34.42%) rose dramatically compared to that of the orally administered Taxotere (6.63%). This increase in bioavailability was probably due to the combined effect of the enhancement in solubility, the inhibition of P-gp efflux system and the increase in permeability. These results encourage further development of docetaxel microemulsions as an oral drug delivery system.