Aptamer based fluorescent probe for serum HER2-ECD detection: The clinical utility in breast cancer

The transmembrane protein HER2 is overexpressed in approximately 30% of breast cancer patients. HER2-positive breast cancers tend to spread more aggressively, which result in increased mortality in women. Nowadays, the real-time monitoring of HER2 status is important in clinical diagnosis and treatment for HER2-positive patients. Although IHC and FISH assay are standard methods to evaluate the tissue HER2 status, both approaches which required high quality tissue samples and are not suitable for monitoring the status of HER2 in real time. Since extracellular domain (ECD) of the HER2 receptor can be shed into the circulation, the serum test of HER2 ECD has been developed as an additional approach to probe HER2 overexpression. The serum test will be able to monitor the dynamic changes of HER2 status. In this paper, we detected serum HER2 ECD using Cy5-labeled HB5 aptamer as a result of its specific binding ability to HER2 ECD. This aptamer-based fluorescent probe is easily synthesized and modified and as sensitive as anti-HER2 antibodies. We believe that Cy5-HB5 may have application potentials in serum HER2 test for clinical utility of breast cancer, such as recurrence and metastases.