Circulating tumor cells (CTCs) have the potential to predict metastasis, and the capture of CTCs based on their surface markers is mostly applied for CTC detection. Considering that the CTCs with a metastatic phenotype preferably form a metastatic focus and that aptamers have the ability to bind targets with high specificity and affinity, we selected aptamers directed toward metastatic cells by subtractive Cell-SELEX technology using highly metastatic MDA-MB-231 cells as the target cell and low-metastatic MCF-7 cells as the negative cell for the capture of metastatic CTCs. Affinity and selectivity assays showed that aptamer M3 had the highest affinity, with a K_D of 45.6 ± 1.2 nM, and had good specificity against several other types of metastatic cancer cells. Based on these findings, we developed an M3-based capture system for CTC enrichment, which has the capability to specifically capture the metastatic cells MDA-MB-231 mixed with non-metastatic MCF-7 cells and CTCs derived from the peripheral blood from metastatic breast cancer patients. A further comparative analysis with the anti-EpCAM probe showed that M3 probe captured epithelial feature-deletion metastatic cells. We developed an aptamer-based CTC capture system through the selection of aptamers by taking whole metastatic cells, not known molecules, as targets, which provided a new insight into CTC capture and Cell-SELEX application.

循环肿瘤细胞（CTC）具有预测转移的潜力，并且基于其表面标记物捕获CTC通常用于CTC检测。考虑到具有转移表型的CTC最好形成转移灶，并且适体具有以高特异性和亲和力结合靶标的能力，我们通过使用高度转移的MDA-MB-231细胞通过消减Cell-SELEX技术选择了针对转移细胞的适体作为目标细胞，将低转移MCF-7细胞作为捕获转移性CTC的阴性细胞。亲和力和选择性测定表明，适体M3的亲和力最高，K _D为45.6±1.2 nM，对多种其他类型的转移性癌细胞具有良好的特异性。基于这些发现，我们开发了一种基于M3的CTC富集捕获系统，该系统能够特异性捕获与非转移性MCF-7细胞和来源于转移性外周血的CTC混合的转移性细胞MDA-MB-231。乳腺癌患者。用抗EpCAM探针进行的进一步比较分析表明，M3探针捕获了上皮特征缺失转移细胞。通过将整个转移细胞（未知分子）作为靶标，通过选择适体，我们开发了基于适体的CTC捕获系统，这为CTC捕获和Cell-SELEX应用提供了新的见识。