Experimental Research Of Screening Biomarkers In The Sera Of Ovarian Carcinoma With Phage Random Peptide Library

Background and Objective: Ovarian carcinoma is a common cancer of female reproductive organs.There are no clinical symptoms in the Early of ovarian carcinoma,though identify histological type and differentiation of its benign or malignant is very difficult.80% of ovarian carcinoma is advanced when found,their 5-year survival rate of only 35%.Patients in the early detection,5-year survival rate is over 90%,many patients will only be cured by surgery.Therefore,improving the early diagnosis of this disease has been a focus of concern of the medical profession.The most commonly used biomarkers of ovarian carcinoma is a tumor antigen CA125,although 80% of the concentration of CA125 in advanced ovarian carcinoma is abnormal.But 50% to 60% of the concentration of CA125 in ovarian carcinoma is not increased.CA125 as a marker, the positive predictive value of less than 10%.Therefore,finding a higher sensitivity and greater specificity of tumor molecular marker will be need.Screening phage display libraries of peptides is a powerful technology for selecting polypeptides or proteins.Fragments of foreign peptides or proteins are expressed as fusion proteins displayed on the pHage surface,keeping their relatively independent spatial structure and biological activity.Through a immunoscreening of phage random peptide library with target protein,we obtain the single phage clone and the specific peptide.Then the peptide can be sequenced to obtain the corresponding information,such as the structure and the function.So we use the technology to search new antigen peptides and provide new markers for the diagnosis and prognosis of ovarian carcinoma.Methods: 1.Serum of patients with ovarian carcinoma was used to immunoscreen a pHage random peptide library of 12 anmino acid residues displayed as a fusion protein.The positive clones were obtained through three rounds of biopanning;2.The reactivity of each clone bound to the sera was examined by ELISA. Finally,we selected the best 1 clones could bind to the sera from ovarian carcinoma patients.3.The positive clones were sequenced with -96â…¢primers, we obtain the protein and the peptides.4.In accordance with the short peptide sequence of synthetic peptides,take the inhibit experiment, identification of the specificity.Results: 1. After three rounds of screening, picked single phage by the repeated identification obtained seven good specific phage; 2. The sequence of the seven phage were carried by the same sequence; 3. The identification of peptide sequence showed no significant difference between the serum of CA125-negative or positive ovarian carcinoma by ELISA; 4. The peptide sequences were identified in the serum of ovarian carcinoma, breast, cervical cancer revealed that the peptide sequence had the specific binding in serum of ovarian cancer by ELISA; 5. The inhibition experiments confirmed that the peptide sequence had the specific binding in the serum of ovarian carcinoma.Conclusion:Ovarian carcinoma antigen peptides from immunoscreening of phage random peptide library supply candidate biomarkers of diagnose, combined detection and immunotherapy of ovarian carcinoma.