Determining the binding affinities of prostate-specific antigen to lectins: SPR and microarray approaches

Prostate cancer (PCa) is one of the most common newly diagnosed cancers among men and we focused on its traditional biomarker, prostate-specific antigen (PSA), using targeted glycomics-based strategies. The aberrant glycosylation pattern of PSA may serve as a valuable tool for improving PCa diagnosis including its early-stage. In this study, we evaluated the usability of two techniques, surface plasmon resonance and protein microarray assay, for the study and characterization of interactions of PSA (both free and complexed) with six lectins (SNA, ConA, RCA, AAL, WGA and MAA II). The information on the character of such interactions is important for the application of lectins as prospective bioreceptors for biomarker glycoprofiling in a follow-up biosensing assays. SPR as well as established bioanalytical techniques allowed determination of K_D values of PSA-lectin interactions in a more reliable way than protein microarray. The protein microarray method did not allow accurate quantification of K_D values. However, the features of a microarray approach, such as speed and costs, enabled the screening and estimation of the nature of lectin-glycan biomarker interaction in an effective and time-saving way. All of the tested lectins interacted with commercial PSA standard isolated from healthy persons, except MAA II which reacted only very weakly.