Screening of molecular markers for early diagnosis of colorectal cancer by phage-peptide library

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 × 106pfu.(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.