A DNA aptamer was identified against the shared tumor-specific MAGE-A3111–125 peptide antigen. The dissociation constant between the aptamer and the peptide was measured at 57 nM. Binding of the aptamer to seven types of cancer cells, melanoma, breast, colorectal, liver, lung, pancreas and oral cancer, was confirmed with flow cytometry and fluorescence imaging. Cy3-conjugated aptamers signals were specifically localized to the surface of those cancer cells. The results indicate that the DNA aptamer against the shared tumor-specific MAGE-A3 peptide can be used in cancer cell targeting and has the potential for developing into new modalities for the diagnosis of multiple cancers.What's new?
Tumor cells express shared tumor-specific antigens, which are able to induce immune responses when presented by MHC molecules on the cell surface. Here, the authors present a DNA aptamer against the shared tumor-specific antigen MAGE-A3 that discriminates multiple types of cancer cells from normal/noncancerous cells. They also first demonstrate that a peptide antigen resided in the MHC binding cleft on the cell surface can be targeted by a DNA aptamer. The study paves the way for generating a variety of aptamers against the many shared tumor-specific antigens already known, and developing novel strategies for the diagnosis and treatment of cancer.