In vitro selection of DNA aptamers for metastatic breast cancer cell recognition and tissue imaging.

Cancer is a major public health issue, with metastatic cancer accounting for the overwhelming majority of cancer deaths. Early diagnosis and appropriate treatment of metastatic cancer may largely prolong the survival rate and improve the quality of life for patients. In this study, we have identified a panel of DNA aptamers specifically binding to MDA-MB-231 cells derived from metastatic site-pleural effusion, with high affinity after 15 rounds of selections using the cell-based systematic evolution of ligands by exponential enrichment (SELEX) method. The selected aptamers were subjected to flow cytometry and laser confocal fluorescence microscopy to evaluate their binding affinity and selectivity. The aptamer LXL-1 with the highest abundance in the enriched library demonstrated a low K(d) value and excellent selectivity for the recognition of the metastatic breast cancer cells. Tissue imaging results showed that truncated aptamer sequence LXL-1-A was highly specific to the corresponding tumor tissue and displayed 76% detection rate against breast cancer tissue with metastasis in regional lymph nodes. Therefore, on the basis of its excellent targeting properties and functional versatility, LXL-1-A holds great potential to be used as a molecular imaging probe for the detection of breast cancer metastasis. Our result clearly demonstrates that metastatic-cell-based SELEX can be used to generate DNA ligands specifically recognizing metastatic cancer cells, which is of great significance for metastatic cancer diagnosis and treatment.