Generation and characterization of a specific single-chain antibody against DSPP as a prostate cancer biomarker: Involvement of bioinformatics-based design of novel epitopes

Isolation of specific single chain antibodies (scFvs) against key epitopes of cancer markers are applied for cancer immunotherapy and diagnosis. In this study following the prediction of the 3D structure of the DSP part of Dentin sialophosphoprotein (DSPP), the epitope was chosen using in silico programs. Panning process was applied to isolate specific human scFv against the epitope. PCR and DNA fingerprinting differentiated the specific clones, which were evaluated by phage ELISA. Following DNA sequencing, the 3D structure of isolated scFv was modeled and Docked on DSP. Results demonstrated the selection of a specific anti-DSPP scFv with 40% frequency, which reacted significantly with the predicted epitope and PCa patients' urines in ELISA tests (P-value < 0.05). The VH and VL of the isolated scFv were from VH1 and VL3 gene families with several amino acid changes in CDRs and FRs domains. The scFv tightly bound to the DSP epitope with the lowest energy level by hydrogen bonds, cation-pi, hydrophobic and ionic interactions demonstrating the specificity of Ag-Ab interactions. The anti-DSPP scFv selected in this study with significant specificity to DSPP antigen offers a promising new agent for both PCa early detection and treatment of cancers with DSPP expression.