Molecular Assembly of an Aptamer–Drug Conjugate for Targeted Drug Delivery to Tumor Cells

Abstract

The conjugation of antitumor drugs to targeting reagents such as antibodies is a promising method that can increase the efficacy of chemotherapy and reduce their overall toxicity. In this paper, we covalently link an antitumor agent doxorubicin (Dox) to the DNA aptamer sgc8c, which was selected by the cell-SELEX method. In doing so, we expected that this sgc8c-Dox conjugate would specifically kill the target CCRF-CEM (T-cell Acute Lymphoblastic Leukemia, T-cell ALL) cells, but with minimal toxicity towards non-target cells. The results demonstrated that sgc8c-Dox conjugate possesses many of the properties of the sgc8c aptamer, including high binding affinity (K d = 2.0 ± 0.2 nM), and the capability to be efficiently internalized by target cells. Moreover, due to the specific conjugation method, the acid-labile linkage connecting the sgc8c-Dox conjugate can be cleaved inside the acidic endosomal environment. Cell viability tests demonstrate that the sgc8c-Dox conjugates not only possess potency similar to the unconjugated Dox, but also have the required molecular specificity which is lacking in most current targeted drug delivery strategies. Furthermore, we found that nonspecific uptake of membrane-permeable Dox to non-target cell lines could also be inhibited by linking the drug with the aptamer, thus, it makes the conjugates selective to the cells which express higher amounts of target proteins. Compared to the less effective reported Dox-immunoconjugates, this sgc8c-Dox conjugates make targeted chemotherapy more feasible with drugs having various potencies. When combined with the large number of recently created DNA aptamers that specifically target a wide variety of cancer cells, this drug-aptoconjugation method will have broad implications for targeted drug delivery.

DNA Microcapsule for Photo‐Triggered Drug Release Systems

“…[9] Small-molecule drugs, [10][11][12] siRNAs, [13,14] and proteins [9] have been encapsulated in DNA-based nanostructures,a nd such DNA vehicles have potentiala sm ultivalent drug delivery carriers. Furthermore, conjugation of targeting devices (monoclonal antibodies, [15][16][17] aptamers, [18][19][20] or peptides) [21] enables selective deliveryo fD NA vehicles to specific sites. [9,13,22,23] To release the cargo from the carrier, installation of an active devicet hat responds to externals timuli such as light, pH, or redox is required.…”

Self-assembled, aptamer-tethered DNA nanotrains for targeted transport of molecular drugs in cancer theranostics

“…A theranostic (4) platform with targeted and efficient drug transport would solve these problems, and, by its programmability, DNA nanotechnology has been used for the rational assembly of one-, two-, and three-dimensional nanostructures (5)(6)(7)(8), which have been further studied for biomedical applications, including the passive targeted transport of theranostic agents (9)(10)(11)(12)(13)(14)(15)(16)(17). In addition, aptamers, as specific recognition elements, have been studied for active targeted transport of conventional chemotherapeutic drugs (11,12,(18)(19)(20)(21). Nucleic acid aptamers are single-stranded oligonucleotides with unique intramolecular conformations and specific recognition abilities to cognate targets, including mammalian cancer cells (22)(23)(24)(25)(26).…”

“…Recent biotechnological advancements have led to a variety of targeted drug transport (TDT) strategies based on aptamer-drug conjugates or aptamer-nanomaterial assemblies (11,12,(18)(19)(20)(21)27). However, these strategies have unique limitations that could hamper the transition to clinical application, including (i) complicated design, laborious and uneconomical bulky preparation of myriad ssDNA as building blocks to construct sophisticated nucleic acid-based nanomaterials, or laborious and inefficient preparation of aptamer-drug conjugates (9,11,14,15,17,18); (ii) limited drug payload capacity and the attendant high cost, hampering production scale-up (9,11,14,15,17,18,20,27); (iii) poor biodegradability, causing chronic accumulation of nanomaterials in vivo (28,29); and (iv) limited universality by the requirement of specific aptamer for drug loading (20).…”

N‐Heterocyclic Carbene–Gold(I) Complexes Conjugated to a Leukemia‐Specific DNA Aptamer for Targeted Drug Delivery

“…Possible explanations for the increased cytotoxicity include high affinity and efficient internalization of the aptamer conjugate to the target cells, and the enhanced hydrophilic nature of the drug after conjugation to the aptamer. [14,28] As a tool for monitoring the fate of the aptamer and the NHC-Au conjugate independently, we constructed a dual-tagged aptamer-NHC-Au conjugate. The anthracenyl tag was chosen as a fluorescent signalling agent for the NHC-Au(I) fragment.…”