WD-repeat protein 79 (WDR79), a member of the WD-repeat protein family, acts as a scaffold protein, participating in telomerase assembly, Cajal body formation and DNA double-strand break repair. Here, we first report that WDR79 is frequently overexpressed in cell lines and tissues derived from non-small cell lung cancer (NSCLC). Knockdown of WDR79 significantly inhibited the proliferation of NSCLC cells in vitro and in vivo by inducing cell cycle arrest and apoptosis. WD-repeat protein 79 -induced cell cycle arrest at the G0/G1 phase was associated with the expression of G0/G1-related cyclins and cyclin-dependent kinase complexes. We also provide evidence that WDR79 knockdown induces apoptosis via a mitochondrial pathway. Collectively, these results suggest that WDR79 is involved in the tumorigenesis of NSCLC and is a potential novel diagnostic marker and therapeutic target for NSCLC.

Intercellular connections are an important pathway for cell–cell crosstalk. However, their formation mechanism and functions are far from being understood. The lack of molecular probes hampers the research in this area. Herein, we report a kind of intercellular connection that is specifically recognized by aptamer M17A2 generated by cell-SELEX against MCF-7R cells. These connections have different morphologies, but have the same skeleton composed of F-actin. The long filamentous connections were identified to be tunneling nanotubes (TNTs), a recently discovered cell–cell communication route. These connections could be built not only between MCF-7R cells, but also from MCF-7R to other cells after co-culture. Proteins could be transported between cells through these connections, suggesting their cell communication function. Aptamer M17A2 shows the potential to act as a new probe for investigating this kind of intercellular connection, as well as for studying cell–cell communication.

A facile strategy has been developed to synthesize double-shelled Zn(OH)₂ nanoflowers (DNFs) at room temperature. The nanoflowers were generated via conversion of Cu₂O nanoparticles (NPs) using ZnCl₂ and Na₂S₂O₃ by a simple process. Outward diffusion of the Cu²⁺, produced by an oxidation process on the surface of NPs, and the inward diffusion of Zn²⁺ by coordination and migration, eventually lead to a hollow cavity in the inner NPs with a double-shelled 3D hollow flower shapes. The thickness of the inner and outer shells is estimated to be about 20 nm, and the thickness of nanopetals is about 7 nm. The nanoflowers have large surface areas and excellent adsorption properties. As a proof of potential applications, the DNFs exhibited an excellent ability to remove organic molecules from aqueous solutions.

Intercellular connections are an important pathway for cell–cell crosstalk. However, their formation mechanism and functions are far from being understood. The lack of molecular probes hampers the research in this area. Herein, we report a kind of intercellular connection that is specifically recognized by aptamer M17A2 generated by cell-SELEX against MCF-7R cells. These connections have different morphologies, but have the same skeleton composed of F-actin. The long filamentous connections were identified to be tunneling nanotubes (TNTs), a recently discovered cell–cell communication route. These connections could be built not only between MCF-7R cells, but also from MCF-7R to other cells after co-culture. Proteins could be transported between cells through these connections, suggesting their cell communication function. Aptamer M17A2 shows the potential to act as a new probe for investigating this kind of intercellular connection, as well as for studying cell–cell communication.

Guanine (G)-rich oligonucleotides have attracted considerable interest as therapeutic agents. Two G-rich aptamers were selected against epidermal growth factor receptor (EGFR)-transfected A549 cells, and their G-rich domains (S13 and S50) were identified to account for the binding of parental aptamers. Circular dichroism (CD) spectra showed that S13 and S50 bound to their targets by forming parallel quadruplexes. Their binding, internalization, and antiproliferation activity in cancer and noncancer cells were investigated by flow cytometry and 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium

(MTS) assay, and compared with those of nucleolin-binding AS1411 and thrombin-binding aptamer. The two truncated aptamers (S13 and S50) have good binding and internalization in cancer cells and noncancer cells; however, only S50, similar to AS1411, shows potent antiproliferation against cancer cells. Our data suggest that tumor-selective antiproliferation of G-rich oligonucleotides does not directly depend on the binding of the G-rich aptamer to cells.

In the past two decades, the study of cancer therapy has gradually advanced to the “nano” era. Numerous novel nanomaterials armed with unique physical properties have been introduced into biomedical research. At the same time, functional nucleic acid molecules, especially aptamers, have aroused broad attention from the biomedical community. Benefiting from the advancement of molecular engineering strategies, it is now feasible to combine the cancer-specific recognition capability of aptamers with various other special functions of nanomaterials to develop cancer-specific drugs at the nanoscale. Nanodrugs are now offering an unprecedented opportunity to achieve the goal of efficient targeted delivery as well as controlled release. This review highlights some achievements made in multiple aptamer-based nanodrug systems that have emerged in recent years, including studies in the infant stage of “proof-of-concept”.

Aptamers are emerging as promising therapeutic agents and recognition elements. In particular, cell-SELEX (systematic evolution of ligands by exponential enrichment) allows in vitro selection of aptamers selective to whole cells without prior knowledge of the molecular signatures on the cell surface. The advantage of aptamers is their high affinitiy and binding specificity towards the target. This Minireview focuses on single-stranded (ss) oligonucleotide (DNA or RNA)-based aptamers as cancer therapeutics/theranostics. Specifically, aptamer–nanomaterial conjugates, aptamer–drug conjugates, targeted phototherapy and targeted biotherapy are covered in detail. In reviewing the literature, the potential of aptamers as delivery systems for therapeutic and imaging applications in cancer is clear, however, major challenges remain to be resolved, such as the poorly understood pharmacokinetics, toxicity and off-target effects, before they can be fully exploited in a clinical setting.

DNAzymes hold promise for gene-silencing therapy, but the lack of sufficient cofactors in the cell cytoplasm, poor membrane permeability, and poor biostability have limited the use of DNAzymes in therapeutics. We report a DNAzyme–MnO₂ nanosystem for gene-silencing therapy. MnO₂ nanosheets adsorb chlorin e6-labelled DNAzymes (Ce6), protect them from enzymatic digestion, and efficiently deliver them into cells. The nanosystem can also inhibit ¹O₂ generation by Ce6 in the circulatory system. In the presence of intracellular glutathione (GSH), MnO₂ is reduced to Mn²⁺ ions, which serve as cofactors of 10–23 DNAzyme for gene silencing. The release of Ce6 generates ¹O₂ for more efficient photodynamic therapy. The Mn²⁺ ions also enhance magnetic resonance contrast, providing GSH-activated magnetic resonance imaging (MRI) of tumor cells. The integration of fluorescence recovery and MRI activation provides fluorescence/MRI bimodality for monitoring the delivery of DNAzymes.

DNAzymes hold promise for gene-silencing therapy, but the lack of sufficient cofactors in the cell cytoplasm, poor membrane permeability, and poor biostability have limited the use of DNAzymes in therapeutics. We report a DNAzyme–MnO₂ nanosystem for gene-silencing therapy. MnO₂ nanosheets adsorb chlorin e6-labelled DNAzymes (Ce6), protect them from enzymatic digestion, and efficiently deliver them into cells. The nanosystem can also inhibit ¹O₂ generation by Ce6 in the circulatory system. In the presence of intracellular glutathione (GSH), MnO₂ is reduced to Mn²⁺ ions, which serve as cofactors of 10–23 DNAzyme for gene silencing. The release of Ce6 generates ¹O₂ for more efficient photodynamic therapy. The Mn²⁺ ions also enhance magnetic resonance contrast, providing GSH-activated magnetic resonance imaging (MRI) of tumor cells. The integration of fluorescence recovery and MRI activation provides fluorescence/MRI bimodality for monitoring the delivery of DNAzymes.

The application of cancer theranostics depends on the development of multifunctional nanostructured platforms for accurate cell targeting and controlled drug release, imaging, and therapy. Herein, a comprehensive, easily fabricated anticancer theranostic platform with a high drug-loading capacity, termed an aptamer-functionalized calcium carbonate (CaCO₃) nanostructure (apt-CCN), is reported. Flow cytometry and confocal fluorescence microscopy studies demonstrate that apt-CCNs can specifically bind to target cancer cells, but not to control cells, and that they possess highly efficient internalization to target cancer cells. This smart nanostructure selectively reaches the lysosomes through receptor-mediated endocytosis and is responsive to the relatively low lysosome pH (4.5–5.5), which facilitates the release of doxorubicin. The apt-CCN platform offers targeted and efficient drug transport, as well as target-specific delivery of imaging agents for cancer diagnosis and therapy.

The development of nanomaterials that combine diagnostic and therapeutic functions within a single nanoplatform is extremely important for molecular medicine. Molecular imaging with simultaneous diagnosis and therapy will provide the multimodality needed for accurate diagnosis and targeted therapy. Here, gold-coated iron oxide (Fe₃O₄@Au) nanoroses with five distinct functions are demonstrated, integrating aptamer-based targeting, magnetic resonance imaging (MRI), optical imaging, photothermal therapy. and chemotherapy into one single probe. The inner Fe₃O₄ core functions as an MRI agent, while the photothermal effect is achieved through near-infrared absorption by the gold shell, causing a rapid rise in temperature and also resulting in a facilitated release of the anticancer drug doxorubicin carried by the nanoroses. Where the doxorubicin is released, it is monitored by its fluorescence. Aptamers immobilized on the surfaces of the nanoroses enable efficient and selective drug delivery, imaging, and photothermal effect with high specificity. The five-function-embedded nanoroses show great advantages in multimodality.

We present a facile approach to make aptamer-conjugated FRET (fluorescent resonance energy transfer) nanoflowers (NFs) through rolling circle replication for multiplexed cellular imaging and traceable targeted drug delivery. The NFs can exhibit multi-fluorescence emissions by a single-wavelength excitation as a result of the DNA matrix covalently incorporated with three dye molecules able to perform FRET. Compared with the conventional DNA nanostructure assembly, NF assembly is independent of template sequences, avoiding the otherwise complicated design of DNA building blocks assembled into nanostructures by base-pairing. The NFs were uniform and exhibited high fluorescence intensity and excellent photostability. Combined with the ability of traceable targeted drug delivery, these colorful DNA NFs provide a novel system for applications in multiplex fluorescent cellular imaging, effective screening of drugs, and therapeutic protocol development.

We present a facile approach to make aptamer-conjugated FRET (fluorescent resonance energy transfer) nanoflowers (NFs) through rolling circle replication for multiplexed cellular imaging and traceable targeted drug delivery. The NFs can exhibit multi-fluorescence emissions by a single-wavelength excitation as a result of the DNA matrix covalently incorporated with three dye molecules able to perform FRET. Compared with the conventional DNA nanostructure assembly, NF assembly is independent of template sequences, avoiding the otherwise complicated design of DNA building blocks assembled into nanostructures by base-pairing. The NFs were uniform and exhibited high fluorescence intensity and excellent photostability. Combined with the ability of traceable targeted drug delivery, these colorful DNA NFs provide a novel system for applications in multiplex fluorescent cellular imaging, effective screening of drugs, and therapeutic protocol development.

Researchers increasingly visualize a significant role for artificial biochemical logical systems in biological engineering, much like digital logic circuits in electrical engineering. Those logical systems could be utilized as a type of servomechanism to control nanodevices in vitro, monitor chemical reactions in situ, or regulate gene expression in vivo. Nucleic acids (NA), as carriers of genetic information with well-regulated and predictable structures, are promising materials for the design and engineering of biochemical circuits. A number of logical devices based on nucleic acids (NA) have been designed to handle various processes for technological or biotechnological purposes. This article focuses on the most recent and important developments in NA-based logical devices and their evolution from in vitro, through cellular, even towards in vivo biological applications.

Human telomerase is a polymerase enzyme that adds tandem repeats of DNA (TTAGGG) in the telomeric region to the ends of chromosomes. Since telomerase can be detected in immortalized, but not normal, somatic cells, it has been considered a selective target for cancer chemotherapy. Here, we describe a DNAzyme-based probe to detect the presence of telomerase in cell lysates. Telomerase elongates the primer site on the probe. Subsequent addition of the Pb^II cofactor activates the DNAzyme, which cleaves the elongated fragment at the RNA site, releasing the probe for repetitive cycling and signal amplification. The cleaved fragment is detected by a reporter molecular beacon. Enzymatic amplification with rapid turnover allows detection of telomerase in the range of 0.1 to 1 μg cell lysate, with a fivefold increase in signal level for cancer cells over normal cells. This probe design can provide a simple, yet rapid and sensitive, measurement of telomerase activity.

Breast cancer affects one in eight women in the United States, with a mortality rate that is second only to lung cancer. Although chemotherapy is widely used in breast cancer treatment, its side effects remain a challenge. One way to address this problem is through drug delivery by the internalization of cell-type-specific probes. Although nucleic acid aptamers are excellent probes for molecular recognition, only a few studies have demonstrated that aptamers can be internalized into living cells. Therefore, herein we report the development of a cancer-cell-specific DNA aptamer probe, KMF2-1a. By using the cell-SELEX method, this aptamer was selected against breast cancer cell line MCF-10AT1. Our results show that KMF2-1a is internalized efficiently and specifically to the endosome of target breast cancer cells. These results indicate that KMF2-1a is a promising agent for cell-type-specific intracellular delivery with both diagnostic and therapeutic implications.

Monovalent aptamers can deliver drugs to target cells by specific recognition. However, different cancer subtypes are distinguished by heterogeneous biomarkers and one single aptamer is unable to recognize all clinical samples from different patients with even the same type of cancers. To address heterogeneity among cancer subtypes for targeted drug delivery, as a model, we developed a drug carrier with a broader recognition range of cancer subtypes. This carrier, sgc8c-sgd5a (SD), was self-assembled from two modified monovalent aptamers. It showed bispecific recognition abilities to target cells in cell mixtures; thus broadening the recognition capabilities of its parent aptamers. The self-assembly of SD simultaneously formed multiple drug loading sites for the anticancer drug doxorubicin (Dox). The Dox-loaded SD (SD–Dox) also showed bispecific abilities for target cell binding and drug delivery. Most importantly, SD–Dox induced bispecific cytotoxicity in target cells in cell mixtures. Therefore, by broadening the otherwise limited recognition capabilities of monovalent aptamers, bispecific aptamer-based drug carriers would facilitate aptamer applications for clinically heterogeneous cancer subtypes that respond to the same cancer therapy.

Functional nanomaterials based on molecular self-assembly hold great promise for applications in biomedicine and biotechnology. However, their efficacy could be a problem and can be improved by precisely controlling the size, structure, and functions. This would require a molecular engineering design capable of producing monodispersed functional materials characterized by beneficial changes in size, shape, and chemical structure. To address this challenge, we have designed and constructed a series of amphiphilic oligonucleotide molecules. In aqueous solutions, the amphiphilic oligonucleotide molecules, consisting of a hydrophilic oligonucleotide covalently linked to hydrophobic diacyllipid tails, spontaneously self-assemble into monodispersed, three-dimensional micellar nanostructures with a lipid core and a DNA corona. These hierarchical architectures are results of intermolecular hydrophobic interactions. Experimental testing further showed that these types of micelles have excellent thermal stability and their size can be fine-tuned by changing the length of the DNA sequence. Moreover, in the micelle system, the molecular recognition properties of DNA are intact, thus, our DNA micelles can hybridize with complimentary sequences while retaining their structural integrity. Importantly, when interacting with cell membranes, the highly charged DNA micelles are able to disintegrate themselves and insert into the cell membrane, completing the process of internalization by endocytosis. Interestingly, the fluorescence was found accumulated in confined regions of cytosole. Finally, we show that the kinetics of this internalization process is size-dependent. Therefore, cell permeability, combined with small sizes and natural nontoxicity are all excellent features that make our DNA–micelles highly suitable for a variety of applications in nanobiotechnology, cell biology, and drug delivery systems.

Molecular beacons (MBs) are specifically designed DNA hairpin structures that are widely used as fluorescent probes. Applications of MBs range from genetic screening, biosensor development, biochip construction, and the detection of single-nucleotide polymorphisms to mRNA monitoring in living cells. The inherent signal-transduction mechanism of MBs enables the analysis of target oligonucleotides without the separation of unbound probes. The MB stem–loop structure holds the fluorescence-donor and fluorescence-acceptor moieties in close proximity to one another, which results in resonant energy transfer. A spontaneous conformation change occurs upon hybridization to separate the two moieties and restore the fluorescence of the donor. Recent research has focused on the improvement of probe composition, intracellular gene quantitation, protein–DNA interaction studies, and protein recognition.

Molecular Beacons (MBs) sind spezifisch entworfene DNA-Haarnadelstrukturen, die als Fluoreszenzsonden für verschiedenste Zwecke eingesetzt werden. Die Anwendungen reichen von genetischem Screening über die Herstellung von Biochips und den Nachweis von Einzelnucleotidpolymorphien bis hin zum mRNA-Monitoring in lebenden Zellen und der Untersuchung von Protein-Protein-Wechselwirkungen. Ermöglicht wird dieses breite Anwendungsspektrum durch die besondere Art, mit der MBs mit DNA-, RNA- und Proteinmolekülen wechselwirken. Durch die Haarnadelstruktur der MBs wird eine enge Nachbarschaft zwischen einem Fluoreszenzdonor und einem -akzeptor hergestellt, wodurch es zu einem resonanten Energietransfer kommt. Die Hybridisierung der Schleifenregion mit der Zielsequenz bewirkt eine Konformationsänderung der Sonden, die den Donor und Akzeptor auseinanderbewegt und die Fluoreszenz wieder herstellt. Die aktuelle Forschung zielt auf die Verbesserung der Sonden, die intrazelluläre Quantifizierung von Genen und die Anwendung in Studien von Protein-Protein-Wechselwirkungen.

Nucleic acid aptamers have been shown many unique applications as excellent probes in molecular recognition. However, few examples are reported which show that aptamers can be internalized inside living cells for aptamer functional studies and for targeted intracellular delivery. This is mainly due to the limited number of aptamers available for cell-specific recognition, and the lack of research on their extra- and intracellular functions. One of the major difficulties in aptamers' in vivo application is that most of aptamers, unlike small molecules, cannot be directly taken up by cells without external assistance. In this work, we have studied a newly developed and cell-specific DNA aptamer, sgc8. This aptamer has been selected through a novel cell selection process (cell-SELEX), in which whole intact cells are used as targets while another related cell line is used as a negative control. The cell-SELEX enables generation of multiple aptamers for molecular recognition of the target cells and has significant advantages in discovering cell surface binding molecules for the selected aptamers. We have studied the cellular internalization of one of the selected aptamers. Our results show that sgc8 is internalized efficiently and specifically to the lymphoblastic leukemia cells. The internalized sgc8 aptamers are located inside the endosome. Comparison studies are done with the antibody for the binding protein of sgc8, PTK7 (Human protein tyrosine kinase-7) on cell surface. We also studied the internalization kinetics of both the aptamer and the antibody for the same protein on the living cell surface. We have further evaluated the effects of sgc8 on cell viability, and no cytotoxicity is observed. This study indicates that sgc8 is a promising agent for cell-type specific intracellular delivery.

Early diagnosis is the way to improve the rate of lung cancer survival, but is almost impossible today due to the lack of molecular probes that recognize lung cancer cells sensitively and selectively. We developed a new aptamer approach for the recognition of specific small-cell lung cancer (SCLC) cell-surface molecular markers. Our approach relies on cell-based systematic evolution of ligands by exponential enrichment (cell-SELEX) to evolve aptamers for whole live cells that express a variety of surface markers representing molecular differences among cancer cells. When applied to different lung cancer cells including those from patient samples, these aptamers bind to SCLC cells with high affinity and specificity in various assay formats. When conjugated with magnetic and fluorescent nanoparticles, the aptamer nanoconjugates could effectively extract SCLC cells from mixed cell media for isolation, enrichment, and sensitive detection. These studies demonstrate the potential of the aptamer approach for early lung cancer detection.