Targeted Nanoparticles Harboring Jasmine-Oil-Entrapped Paclitaxel for Elimination of Lung Cancer Cells.

Selectively targeted drug delivery systems are preferable chemotherapeutic platforms, as they specifically deliver the drug cargo into tumor cells, while minimizing untoward toxic effects. However, these delivery systems suffer from insufficient encapsulation efficiency (EE), encapsulation capacity (EC), and premature drug release. Herein, we coencapsulated paclitaxel (PTX) and Jasmine oil (JO) within PEG-PCL nanoparticles (NPs), with an average diameter < 50 nm, selectively targeted to non-small cell lung cancer (NSCLC) cells, via S15-aptamer (APT) decoration. JO was selected as an "adhesive" oily core to enhance PTX entrapment, as JO and PTX share similar hydrophobicity and terpenoid structure. JO markedly enhanced EE of PTX from 23% to 87.8% and EC from 35 ± 6 to 74 ± 8 µg PTX/mg PEG-PCL. JO also markedly increased the residual amount of PTX after 69 h, from 18.3% to 65%. Moreover, PTX cytotoxicity against human NSCLC A549 cells was significantly enhanced due to the co-encapsulation with JO; the IC50 value for PTX encapsulated within JO-containing APT-NPs was 20-fold lower than that for APT-NPs lacking JO. Remarkably, JO-containing APT-NPs displayed a 6-fold more potent cell-killing, relatively to the free-drug. Collectively, these findings reveal a marked synergistic contribution of JO to the cytotoxic activity of APT-NP-based systems, for targeted PTX delivery against NSCLC, which may be readily applied to various hydrophobic chemotherapeutics.

Selective Targeting and Eradication of Various Human Non-Small Cell Lung Cancer Cell Lines Using Self-Assembled Aptamer-Decorated Nanoparticles.

The leading cause of cancer mortality remains lung cancer (LC), of which non-small cell lung cancer (NSCLC) is the predominant type. Chemotherapy achieves only low response rates while inflicting serious untoward toxicity. Herein, we studied the binding and internalization of S15-aptamer (S15-APT)-decorated polyethylene glycol-polycaprolactone (PEG-PCL) nanoparticles (NPs) by various human NSCLC cell lines. All the NSCLC cell lines were targeted by S15-APT-decorated NPs. Confocal microscopy revealed variable levels of NP binding and uptake amongst these NSCLC cell lines, decreasing in the following order: Adenocarcinoma (AC) A549 cells > H2228 (AC) > H1299 (large cell carcinoma) > H522 (AC) > H1975 (AC). Flow cytometry analysis showed a consistent variation between these NSCLC cell lines in the internalization of S15-APT-decorated quantum dots. We obtained a temperature-dependent NP uptake, characteristic of active internalization. Furthermore, cytotoxicity assays with APT-NPs entrapping paclitaxel, revealed that A549 cells had the lowest IC50 value of 0.03 µM PTX (determined previously), whereas H2228, H1299, H522 and H1975 exhibited higher IC50 values of 0.38 µM, 0.92 µM, 2.31 µM and 2.59 µM, respectively (determined herein). Cytotoxicity was correlated with the binding and internalization of APT-NPs in the various NSCLC cells, suggesting variable expression of the putative S15 target receptor. These findings support the development of APT-targeted NPs in precision nanomedicine for individual NSCLC patient treatment.

Selective eradication of human non-small cell lung cancer cells using aptamer-decorated nanoparticles harboring a cytotoxic drug cargo.

Targeted cancer therapy is currently the leading modality to enhance treatment selectivity and efficacy, as well as to minimize untoward toxicity to healthy tissues. Herein, we devised and studied nanoparticles (NPs) composed of the biocompatible block-copolymer PEG-PCL entrapping the hydrophobic chemotherapeutic drug paclitaxel (PTX), which are targeted to human non-small cell lung cancer (NSCLC) cells. To achieve selective NSCLC targeting, these NPs were decorated with single-stranded oligonucleotide-based S15 aptamers (S15-APTs), which we have recently shown to serve as efficient tumor cell targeting ligands. Prepared without using surfactants, these 15 nm PEG-PCL/PTX NPs entered NSCLC cells via clathrin-mediated endocytosis. These NPs demonstrated efficient encapsulation of PTX, high selectivity to- and potent eradication of human A549 NSCLC cells, with a remarkable half maximal inhibitory concentration (IC50) of 0.03 µM PTX. In contrast, very high IC50 values of 1.7, 4.2, 43, 87, and 980 µM PTX were obtained towards normal human bronchial epithelial BEAS2B, cervical carcinoma HeLa, colon adenocarcinoma CaCo-2, neonatal foreskin fibroblast FSE, and human embryonic kidney HEK-293 cells, respectively. These results demonstrate 2-5 orders of magnitude difference in the selective cytotoxicity towards NSCLCs, reflecting a potentially outstanding therapeutic window. Moreover, the dual utility of aptamer-decorated NPs for both drug stabilization and selective tumor targeting was studied by increasing APT concentrations during NP "decoration". The optimal aptamer density on the surface of NPs for selective targeting, for high fluorescence diagnostic signal and for maintaining small particle size to enable endocytosis, was achieved by using 30 nM APTs during NP decoration. Collectively, our findings suggest that these APT-decorated NPs hold great preclinical promise in selective targeting and eradication of human NSCLC cells without harming normal tissues.

Cancer cell-selective, clathrin-mediated endocytosis of aptamer decorated nanoparticles.

Lung cancer is the leading cause of cancer mortality worldwide, resulting in 88% deaths of all diagnosed patients. Hence, novel therapeutic modalities are urgently needed. Single-stranded oligonucleotide-based aptamers (APTs) are excellent ligands for tumor cell targeting. However, the molecular mechanisms underlying their internalization into living cells have been poorly studied. Towards the application of APTs for active drug targeting to cancer cells, we herein studied the mechanism underlying S15-APT internalization into human non-small cell lung cancer A549 cells. We thus delineated the mode of entry of a model nanomedical system based on quantum dots (QDs) decorated with S15-APTs as a selective targeting moiety for uptake by A549 cells. These APT-decorated QDs displayed selective binding to, and internalization by target A549 cells, but not by normal human bronchial epithelial BEAS2B, cervical carcinoma (HeLa) and colon adenocarcinoma CaCo-2 cells, hence demonstrating high specificity. Flow cytometric analysis revealed a remarkably low dissociation constant of S15-APTs-decorated QDs to A549 cells (Kd = 13.1 ± 1.6 nM). Through the systematic application of a series of established inhibitors of known mechanisms of endocytosis, we show that the uptake of S15-APTs proceeds via a classical clathrin-dependent receptor-mediated endocytosis. This cancer cell-selective mode of entry could possibly be used in the future to evade plasma membrane-localized multidrug resistance efflux pumps, thereby overcoming an important mechanism of cancer multidrug resistance.