Selection of Aptamers for Molecular Recognition and Characterization of Cancer Cells

TLDR

Molecular medicine demands many probes for recognizing and characterizing diseased cells, and aptamers—single‑stranded DNA/RNA probes—are poised to serve as chemist‑friendly antibodies for diverse biomedical applications. The paper presents a novel method to generate molecular probes that specifically recognize cancer cells. The authors employed cell‑based SELEX on Ramos B‑cell lymphoma cells to evolve aptamer panels from an initial DNA library. The cell‑based SELEX produced aptamers that bind Ramos lymphoma cells and related lines with nanomolar affinity, can discriminate target cells in mixed bone marrow samples, and offers a simple, fast, robust platform for diagnostics, therapy, and biomarker discovery.

Abstract

In this paper, we describe a new way to generate molecular probes for specific recognition of cancer cells. Molecular medicine will require a large number of probes for molecular recognition and characterization of a variety of diseased cells. Aptamers, single-stranded DNA/RNA probes, are poised to become a chemist's antibody and have the potential to serve as molecular probes for a variety of biomedical applications. By applying newly developed cell-SELEX (cell-based systematic evolution of ligands by exponential enrichment) against whole living cells, panels of aptamers have been evolved from an initial DNA library to characterize target cells at the molecular level. Ramos cells, a B-cell lymphoma cell line, were used as target cells for the generation of effective molecular probes. By taking advantages of the repetitive and broad enrichment strategy, the selected aptamers could bind to target cells and other closely related cell lines in variant patterns with an equilibrium dissociation constant (Kd) in the nanomolar range. Some aptamers could also specifically recognize the target lymphoma cells mixed with normal human bone marrow aspirates. The cell-based SELEX is simple, fast, and robust. The strategies used here will be highly useful for aptamer selection against complex target samples in order to generate a large number of aptamers in a variety of biomedical and biotechnological applications, paving the way for molecular diagnosis, therapy, and biomarker discovery.