5.1.1. Prominin 1 (PROM1, CD133)-Targeting Probes

CD133 is a kind of glycoprotein mainly expressed in hematopoietic stem and progenitor cells [147]. As a marker of cancer stem cells of brain tumor, colon cancer, melanoma, and ATCs [148–151], it is known to be responsible for the rapid growth of ATC and PTC cells [152,153]. Ge et al. synthesized and characterized an aptamer AP-1-M targeting CD133 in an ATC xenograft model. The synthesized AP-1-M-doxorubicin conjugates can effectively bind CD133-expressing tumor cells, and an intense signal may reflect the tumor proliferation at a fast pace [15] (Figure 13).

**Figure 13.** (**A**) Predicated structure of aptamer precursor AP-1. (**B**) Distribution of AP-1-M in a FRO xenograft model on fluorescence imaging at 48 h post-injection of PBS, Cy5.5-labeled AP-1-M, and control aptamer S30. Reproduced with permission from [15], copyright 2013 Royal Society of Chemistry.
