Identificação de peptídeos imunorreativos contra IgG de soro de pacientes com câncer de próstata por meio da tecnologia phage display

Abstract

Prostate cancer is the second cause of death in men by tumor, surpassed only by lung cancer. Therefore, the identification of new cancer specific antigens and genes may provide important biomarkers for diagnosis and instruments for the development of new treatment strategies. In this investigation the phage display technology have been used to select ligand peptides to serum antibodies of patients with prostate cancer in order to use them in diagnosis as serological biomarkers. Selection of phages was performed in three steps using a random peptide library of 12 residues (Ph.D.-12) expressed in fusion with the pIII protein of the M13 bacteriophage. The first two selection steps consisted of a pre clearing using the phage libraries against sera antibodies (IgG) of healthy individuals, followed by a second selection against total proteins of patients with benign prostatic hyperplasia. After subtraction, the library was submitted to a positive selection against purified IgG from patients with prostate cancer and ligand phages of interest were eluted by affinity with total proteins from prostate tumor tissues. Selected phages were amplified, and DNA was sequenced, translated and submitted to bioinformatic analyzes and ELISA assays. Similarities were found between peptide sequences and proteins deposited in GeneBank associated with adhesion, intra and intercellular trafficking and transcriptional regulation. Among 12 selected peptides, eight presented differential immune reactivity for cancer detection, and four clones for benign prostatic hyperplasia, which may become potential biomarkers for diagnosis of these pathologies.