Dimeric DNA Aptamer Complexes for High-capacity-targeted Drug Delivery Using pH-sensitive Covalent Linkages

Area of Science:

• Biochemistry
• Molecular Biology
• Nanotechnology

Background:

• Doxorubicin (Dox) chemotherapy causes severe systemic toxicities, limiting its clinical efficacy and causing long-term health issues.
• Targeted drug delivery systems are needed to improve cancer treatment by selectively delivering chemotherapeutics to tumor cells while sparing healthy tissues.

Purpose of the Study:

• To develop a novel DNA aptamer-based targeted delivery system for doxorubicin (Dox).
• To create dimeric aptamer complexes (DACs) for specific delivery of Dox to prostate-specific membrane antigen-positive (PSMA+) cancer cells.
• To evaluate the stability, cellular uptake, drug release kinetics, and selective cytotoxicity of the Dox-conjugated DACs (DAC-D).

Main Methods:

• Identification of a DNA aptamer specific for prostate-specific membrane antigen (PSMA).
• Development of dimeric aptamer complexes (DACs) for Dox binding.
• Covalent conjugation of Dox to DACs using a reversible linker to form DAC-D.
• Assessment of DAC-D stability, cellular internalization (confocal microscopy, flow cytometry), Dox release, and cytotoxicity in PSMA+ (C4-2) and PSMA-null (PC3) cancer cells.

Main Results:

• DACs demonstrated specific internalization into PSMA+ C4-2 cells with minimal uptake into PSMA-null PC3 cells.
• The DAC-D complex showed a stable ~4:1 stoichiometry of Dox to aptamer.
• Dox was released from DAC-D under physiological conditions with an 8-hour half-life, enabling targeted delivery.
• DAC-D exhibited selective cytotoxicity towards PSMA+ C4-2 cells, comparable to free Dox, with minimal toxicity to PSMA-null PC3 cells.

Conclusions:

• Dimeric aptamer complexes (DACs) can be effectively engineered for the targeted delivery of doxorubicin (Dox) to PSMA-positive cancer cells.
• The DAC-D system demonstrates high specificity, stability, and selective cytotoxicity, offering a promising strategy for improved cancer therapy.
• This targeted approach has the potential to reduce the systemic toxicity associated with conventional doxorubicin chemotherapy and enhance therapeutic outcomes in vivo.