Characterization of a DNA Aptamer for Ovarian Cancer Clinical Tissue Recognition and in Vivo Imaging

Backgrounds/aims: Ovarian Cancer is the most lethal gynaecologic malignancy and is difficult to detect early. The inefficient early diagnosis of ovarian Cancer is the main contributor to its high mortality rate. Aptamers, as chemical Antibodies, are single-stranded DNA or RNA Oligonucleotides that target cells or molecules with high affinity.

Methods: Binding ability of R13 was measured by flow cytometry analysis. Stability of R13 was tested in blood serum of an ovarian Cancer patient. Internalization of R13 was verified by confocal microscope imaging. 80 cases ovarian Cancer tissues, 10 cases normal ovary tissues in a microarray and 6 fallopian tube tissues were prepared for this study. R13's target ability was further confirmed in vivo tumor models in NOD/SCID mice.

Results: In this study, we found aptamer R13 bound to ovarian Cancer cells with dissociation constants in the nanomolar range. Moreover, these results were further confirmed by tissue imaging. Next we demonstrated that the targets of R13 are membrane proteins and that its internalization occurs in a caveolae-mediated and clathrin-mediated manner. The target function of R13 was determined by imaging A2780 tumours in mouse models.

Conclusion: These findings suggest that R13 is a promising novel tool to diagnose and deliver drugs to treat ovarian Cancer.