DNA aptamer to human lung adenocarcinoma shows antitumor effect
Aptamers are oligonucleotides that can bind with high affinity and specificity to their targets due to their unique three dimensional structure. Moreover, they are becoming increasingly attractive as therapeutic agents as they have demonstrated other virtues, such as antitumor effects. Here we present selection of DNA-aptamers specific to human lung adenocarcinoma tissues obtained immediately after surgery. Flow cytometry was used to compare relative affinities of aptamers to the cancer cells, and aptamers with the highest binding were selected, identified and then evaluated in a cell-based assay. Our findings showed that one of the aptamers has the potential to inhibit growth of primary cancer cell cultures without influencing growth of healthy lung cells. Following cell-based assays, we identified a protein target for this aptamer using high performance liquid chromatography and high resolution tandem mass spectrometry. Protein cathepsin D was found to be the most likely target for this aptamer; it is associated with cancer growth, invasion and metastasis, and more recently has been considered as a potential target for anticancer therapy. These results are promising and may lead the way toward the development of novel aptamer-based anticancer therapeutics.
Aptamers are single-stranded DNA or RNA oligonucleotides selected from large random-sequence nucleic acid libraries for their selective affinity to different molecular targets (1-6). They fold into well-defined three-dimensional structures (1, 2) and show high affinity and specificity for their targets. Aptamers are often viewed as synthetic affinity probes, with applications ranging from target detection to drug discovery and delivery. These molecules are non-immunogenic and non-toxic; therefore, they have the potential to become good drug candidates (7). Furthermore, aptamers to various cancer cell lines have been found to exhibit anticancer activity themselves as well as in combination with toxins (8, 9). When interacting with molecular targets,