Revolutionizing cancer therapy using tetrahedral DNA nanostructures as intelligent drug delivery systems

Abstract

DNA nanostructures have surfaced as intriguing entities with vast potential in biomedicine, notably in the drug delivery area. Tetrahedral DNA nanostructures (TDNs) have received worldwide attention from among an array of different DNA nanostructures due to their extraordinary stability, great biocompatibility, and ease of functionalization. TDNs could be readily synthesized, making them attractive carriers for chemotherapeutic medicines, nucleic acid therapeutics, and imaging probes. Their varied uses encompass medication delivery, molecular diagnostics, biological imaging, and theranostics. This review extensively highlights the mechanisms of functional modification of TDNs and their applications in cancer therapy. Additionally, it discusses critical concerns and unanswered problems that require attention to increase the future application of TDNs in developing cancer treatment.

Fig. 1. Structural representation of Tetrahedral DNA Nanostructures (TDNs) and their potential for drug loading. (A) Formation of a TDN through self-assembly. Each single strand comprises a complementary sequence to another single strand, resulting in the formation of a tetrahedral structure. (B) Modification in the mosaic region of the tetrahedron for chemotherapy drugs (e.g., doxorubicin, paclitaxel, actinomycin D). (C) Modification in the capsule region for nanoparticles (e.g., AuNPs), cytochrome c, or peptides (e.g., melittin). (D) Modification in the vertex region for molecules such as CpG, aptamers, monoclonal antibodies (mAbs), 5-fluorouracil, or peptides, and (E) modification in the cantilever region for ligands like folate, siRNA, KillerRed, or camptothecin.

Fig. 2. Schematic representation of the intracellular delivery of methylene blue (MB) using a DNA tetrahedron as a carrier. (A) Synthesis of a DNA tetrahedron and loading of MB on the DNA-Td. (B) Evaluation of the cellular uptake efficiency and photodynamic therapy (PDT) effect by MB delivered with the DNA tetrahedron at the cellular level, leading to successful translocation of MB into cells and enhanced potency in vitro. (C) Subsequent demonstration of the effectiveness of MB delivery by the DNA nanocarrier at the in vivo level, resulting in enhanced potency compared to free MB.

Fig. 3. Schematic representation of the functionalized DNA tetrahedron nanoregulator designed to induce endoplasmic reticulum (ER) stress for tumor immunogen exposure and enhanced immunotherapy. (A) The tetrahedron structure, modified with Gox as the ER-targeting ligand (TsG → Gox), facilitates anchoring to ER organelles via binding to cell sulfonamide receptors. Subsequently, Gox-conjugated DNA tetrahedrons are camouflaged by cancer cell membranes to form the nanoregulator. (B) Upon accumulation in ER organelles, the catalytic reaction initiated by Gox depletes glucose and generates hydrogen peroxide (H₂O₂). This induces ER stress, evidenced by upregulated glucose-regulated protein 78 kD (GRP78), triggering immunogenic cell death (ICD) of cancer cells to expose damage-associated molecular patterns (DAMPs), including calreticulin (CRT) proteins and high mobility group box 1 (HMGB1). These DAMPs promote dendritic cell (DC) maturation, characterized by high expression of CD80 and CD86, which in turn present antigens to stimulate T cell proliferation and infiltration, leading to cancer cell destruction. Combined with an immune checkpoint inhibitor (α-PD-1), the nanoregulator demonstrates significant suppression of breast cancer and melanoma growth in tumor-bearing mouse models.

Fig. 4. Schematic representation of the formation of pH-sensitive liposomes encapsulating nanostructured DOX (LNSD), highlighting its benefits in overcoming drug resistance in tumor treatment. (A) An LNSD is formed by loading DOX into transdermal patches (TD) to create small nanostructured DOX (TD/DOX), which is then encapsulated into pH-sensitive liposomes. (B) The resulting LNSD demonstrates enhanced cellular uptake of DOX, sustained drug concentration within resistant tumor cells, improved penetration into cell nuclei, and accumulation at tumor sites via the enhanced permeability and retention (EPR) effect of liposomes. Antitumor efficacy and reversal of DOX resistance were assessed using MCF-7/ADR cells and DOX-resistant breast tumor models.