Abstract
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.
Highlights
Lung cancer is one of the most common malignancies in the world with 1.6 million new cases diagnosed annually, resulting in 1.4 million deaths [1]
The internalization of S15 APT-decorated quantum dots (QDs) was explored by confocal laser microscopy in human A549 Non-small cell lung cancer (NSCLC) cells and compared to normal human bronchial epithelial BEAS2B, cervical carcinoma (HeLa) and colon adenocarcinoma cells (CaCo-2) (Figure 1)
Following an incubation with 50 nM S15-APT QDs for 2 h at 37° C, A549 cells displayed a remarkable internalization of the red fluorescent S15-APT QDs as evidenced by the intense red fluorescent intracellular vesicles that appeared as possible endosomes (Figure 1A)
Summary
Lung cancer is one of the most common malignancies in the world with 1.6 million new cases diagnosed annually, resulting in 1.4 million deaths [1]. The main drawbacks of chemotherapeutic treatments are the side effects causing untoward toxicity to healthy tissues and organ dysfunction, where cells are continuously dividing (e.g. bone marrow and gastrointestinal tract) This results in www.oncotarget.com myelosuppression and mucosal epithelium dysfunction, thereby enhancing patient vulnerability to life-threatening pathogenic infections [3]. Another major hindrance towards curative cancer treatment is the frequent emergence of multidrug resistance (MDR), predominantly mediated by efflux transporters of the ATP-binding cassette (ABC) superfamily including P-glycoprotein (P-gp). The latter expels numerous structurally and functionally distinct chemotherapeutics from cancer cells thereby abolishing their cytotoxic activity [4]. Targeted delivery into cancer cells via endocytosis is expected to enable the use of minimal drug doses with maximal treatment efficacy, while dramatically reducing the cost of treatment
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
