ABSTRACT
Nucleic acids that bind to cells and are subsequently internalized could prove to be novel delivery reagents. An anti-prostate specific membrane antigen aptamer that has previously been shown to bind to prostate tumor cells was coupled to siRNAs via a modular streptavidin bridge. The resulting conjugates could be simply added onto cells without any further preparation, and were taken up within 30 min. The siRNA-mediated inhibition of gene expression was as efficient as observed with conventional lipid-based reagents, and was dependent upon conjugation to the aptamer. These results suggest new venues for the therapeutic delivery of siRNAs and for the development of reagents that can be used to probe cellular physiology.
Subject(s)
Aptamers, Nucleotide/chemistry , RNA Interference , RNA, Small Interfering/administration & dosage , Cell Line, Tumor , Humans , Kinetics , Lamins/metabolism , Prostate-Specific Antigen/metabolism , RNA, Small Interfering/chemistry , Streptavidin/chemistryABSTRACT
We have used RNA aptamer:gelonin conjugates to target and specifically destroy cells overexpressing the known cancer biomarker prostate-specific membrane antigen (PSMA). Aptamer:toxin conjugates have an IC50 of 27 nmol/L and display an increased potency of at least 600-fold relative to cells that do not express PSMA. The aptamer not only promotes uptake into target cells but also decreases the toxicity of gelonin in non-target cells. These results validate the notion that "escort aptamers" may be useful for the treatment of specific tumors expressing unique antigen targets.
Subject(s)
Antineoplastic Agents, Phytogenic/administration & dosage , Aptamers, Nucleotide/genetics , Plant Proteins/administration & dosage , Prostatic Neoplasms/drug therapy , Prostatic Neoplasms/genetics , Antineoplastic Agents, Phytogenic/pharmacokinetics , Aptamers, Nucleotide/pharmacokinetics , Cell Line, Tumor , Drug Delivery Systems/methods , Humans , Inhibitory Concentration 50 , Male , Plant Proteins/pharmacokinetics , Prostate-Specific Antigen/biosynthesis , Prostate-Specific Antigen/genetics , Prostate-Specific Antigen/metabolism , Prostatic Neoplasms/metabolism , Ribosome Inactivating Proteins, Type 1ABSTRACT
Aptamers that bind to prostate specific membrane antigen (PSMA) were conjugated to luminescent CdSe and CdTe nanocrystals for cell-labeling studies. The aptamer-nanocrystal conjugates showed specific targeting of both fixed and live cells that overexpressed PSMA. More importantly, aptamers were able to label cells dispersed in a collagen gel matrix simulating tissue. The specific binding abilities and synthetic accessibility of aptamers combined with the photostability and small size of semiconductor nanocrystals offers a powerful and general tool for cellular imaging.
