Selection and characterization of aptamers targeting cancer associated fibroblasts in patients with colorectal cancer.

Cancer-associated fibroblasts (CAFs) are the most abundant stromal cells in the tumor microenvironment, playing an important role in tumor development and progression. Targeting CAFs has become a promising strategy for cancer therapy. However, the high heterogeneity of CAFs poses significant challenges in identifying effective therapeutic targets. Cell-SELEX is a method for screening cell-specific aptamers in the presence of unknown targets, which can also help identify and discover new biomarkers. However, there are currently no reports on aptamer screening targeting microenvironmental cells from solid tumors. In this study, we developed a novel Cell-SELEX strategy using mixed CAFs from different colorectal cancer (CRC) patient tissues as target cells, with a limited number of target cell passages. DNA sequences were enriched by the 5th round, and after 11 rounds of selection, we obtained aptamer F7 with a dissociation constant (Kd) of 15.70 ± 2.47 nM. Aptamer F7 showed good biological stability and excellent specificity, and could specifically distinguish CAFs from normal fibroblasts (NFs) in patients with CRC. Moreover, the F7-positive CAF subpopulation was shown to promote the proliferation, migration and invasion abilities of tumor cells. Competitive binding experiments indicated that the F7 target differs from commonly used CAF markers. Further identification of this target may lead to the discovery of new CAF subgroups and novel diagnostic and therapeutic biomarkers. The screening method proposed here not only extends the application of Cell-SELEX, but also provides a strategy for screening aptamers for cells in complex solid tumor environments.