Screening of molecular markers for early diagnosis of colorectal cancer by phage-peptide library / 第二军医大学学报

ABSTRACT

Objective: To establish a colorectal cancer phage-peptide library and to screen for biomarkers for early detection of colorectal cancer. Methods: A T7 phage display peptide library was constructed using 30 surgical colorectal cancer specimens from Changhai Hospital, Second Military Medical University. Protein-A/G was used to enrich IgG from control sera as well as colorectal cancer sera. Five biopanning protocols were carried out for enrichment of colorectal cancer-specific phage clones, and 2 000 phage clones were randomly selected. ELISA was used for further screening of clones of different reactivities between the cancer serum and control serum; and the selected clones were subjected to DNA sequencing and the cloned protein function was forecasted by Chilibot for validation. Results: (1) The titer of the colorectal cancer phage display peptide library was 3.0×106pfu, with a recombination rate of 60% as showed by PCR identification and a storage capacity of 1.8×106 pfu. (2) Of the 18 phage clones selected by ELISA, 12 were cancer-related genes. Conclusion: ELISA for screening the recombinant tumor antigen phage display peptide library can be used to discover new differentially expressed antigens ; and the selected phage clones expressing antigen might be used for early detection of colorectal cancer.