Protein glycosylation plays very important roles in biological processes. However, detecting and differentiating such modifications rapidly is not a trivial issue. Therefore, developing novel tools that allow for the rapid detection of glycosylation patterns is of tremendous importance to the field of glycomics. In this application, we propose to develop a novel platform approach for the selection of DNA-based aptamers for glycoproteins with the ability to differentiate glycosylation patterns. The proposed approach is based on our central hypothesis that incorporation of the boronic acid moiety into a DNA library will allow the aptamer selection process to gravitate toward glycosylation recognition due to the well known strong interactions between the boronic acid moiety and diols and hydroxyl groups commonly found on carbohydrates. In Phase 1 of this fast-track R41/R42 application, we propose to examine the feasibility of the proposed method using a model glycoprotein, prostate-specific antigen (PSA) collected from healthy donors. Upon demonstration of feasibility, we will use PSA from cancer patients in Phase 2 and develop aptamers with high affinity and specificity for different isoforms of PSA. We will also work on human chorionic gonadotropin (hCG), which has many glycosylation sites. Variations in glycosylation have been correlated with cancer, Down syndrome, and the health of pregnancy. We also propose to develop a sandwich assay and a kit for examination of PSA and hCG glycosylation isoforms and a method for the large scale chemical synthesis of boronic acid-modified aptamers. At the end of the grant period, we plan to bring to market several products including (1) DNA aptamers and kits for PSA with different glycosylation patterns and (2) various boronic acid-modified TTPs for research labs to develop boronic acid-modified DNA aptamers for glycoproducts of their own interest. At the end of the grant period we should also be ready to do custom selections of DNA aptamers for glycoproducts based on customers'needed and be read to further evaluate the clinical potential of using PSA aptamers as a FDA-approved prostate cancer diagnostics.
The application aims to develop new methods for studying protein modifications that could be one day be used for detecting and diagnosing diseases such as cancer, Down syndrome, and failing pregnancy.
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