Peroxiredoxin-4 as a potential biomarker of early gastric cancer screened by Cell-SELEX

Pan Xu, Mingyang Shao, Ruhan Jia, Wenhui Li, Zhenya Du, Yuewu Han


Background: The objective of this study was to screen and identify a new biomarker for the detection of early gastric cancer. Aptamers are a group of promising probe that can specifically recognize and bind to target molecules and cells.
Methods: Using an aptamer library, we selected high-specificity and high-affinity aptamers through 12 rounds of Cell-SELEX. The target protein could be extracted from early gastric cancer cells with streptavidin magnetic beads method and aptamers; before purification, the target protein was analyzed by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS). The fluorescein-labeled aptamer was used for establishment and analysis of a new detection method for biomarkers. Then we used the ELISA (enzyme-linked immuno sorbent assay) to verify the new detection method.
Results: Ultimately, aptamer 7 (Ap7) was selected as the aptamer with the highest specificity and affinity in the screen, which targeted the early gastric cancer protein named early gastric cancer 7 (EGA7). Based on comparison of sequences in the NCBI database, EGA7 was identified as Peroxiredoxin-4 (Prx4). Further analysis which contained the ELISA results showed a significant difference in EGA7 expression between early gastric cancer tissues and the normal gastric mucosa or advance gastric cancer tissues, confirming its utility as a marker for early gastric cancer. This is the first report using a high-specificity and high-affinity aptamer (Ap7) to screen for an early gastric cancer protein; using this method, a new biomarker, EGA7, was identified.
Conclusions: These results provide the experimental foundation for future research on the use of aptamer libraries and biomarkers for the diagnosis and identification of drug targets in early gastric cancer. And Prx4 has the potential as a biomarker of early gastric cancer.