Metastatic cancer cell and tissue-specific fluorescence imaging using a new DNA aptamer developed by Cell-SELEX.

Metastasis, which derived from a primary tumor, accounts for 90% of mortality caused by cancer. Early diagnosis of cancer metastasis may significantly improve cure rate of patients who are at high risk for developing metastasis. In this study, we successfully achieved metastatic cancer cell and tissue-specific fluorescence imaging by using a new aptamer developed by cell-based systematic evolution of ligands by exponential enrichment (Cell-SELEX). With metastatic colorectal carcinoma LoVo cells as selection target, the aptamer named J3 which bind to metastatic cancer cells with good affinity and specificity was obtained. Then J3 was labeled with Cy5 fluorescent group (J3-Cy5) for imaging metastatic cancer cells, the results demonstrated excellent imaging contrast. Moreover, the results of tissue section imaging revealed that J3-Cy5 probe explicitly recognized lymph node tissue with colorectal carcinoma metastasis with a high detection rate of 73.9%, but showed a low detection rate to colorectal carcinoma tissue with no metastasis or cancer adjacent tissue. Therefore, the targeting reagent J3-based fluorescence imaging possesses great potential for clinical diagnosis of cancer metastasis.