To screen small molecule peptide specific binding to non-small cell lung cancer cell (A549) using the "one-bead one-peptide" combinatorial library. Twenty-nine positive beads binding to A549 cell were totally obtained after primary screening. Consensus peptide sequence of -NGXG-was identified by amino acid sequencing in ten beads. Peptide cNGQGEQc was re-synthesized on beads and further studied for its cell specificity, alanine scanning and site-directed deletion. The results showed that cNGQGEQc is specific for cell attachment to non-small cell lung cancer cells including A549, Calu-1 and H178, but not to other tumor cell lines. Both motif of -NGXG-and the length of six peptides are very important for A549 adhesion. Peptide cNGQGEQc labeled with FITC can specifically bind to A549 cell. In a blocking assay with anti-integrin antibodies(?1～6, ?v/?1～5), cell adhesion of A549 to peptide beads was obviously inhibited by integrin ?3 combining with any ? subunits. Results suggested that small molecule peptide cNGQGEQc can bind specifically to non-small cell lung cancer cell A549 via integrin ?3 on cell surface.

Screen small molecule peptide specific binding to small cell lung cancer cell (DMS53) was screened by using the "one-bead one-peptide" combinatorial technology. Thirty two positive beads binding to DMS53 were totally obtained after primary screening. Consensus peptide sequences of cXNGRXXc and cNGRXXXc were identified by amino acid sequencing in ten beads. Three representative peptides were re-synthesized on beads. Secondary screening showed that cell adhesion percentage of cFNGRQQc to DMSS was higher than the other two peptides. cFNGRQQc was further studied for cell specificity, alanine scanning and site-directed deletion. The results showed that cFNGRQQc is specific for promoting cell adhesion to DMS53 but not to other human cell lines. Both motif of -NGR- and the length of six peptide of cFNGRQQc structure are important for DMS53 attachment. In an antibody or peptide blocking assay, cell adhesion of DMS53 to peptide bead was not inhibited by antibodies or peptides including anti-integrin, E-cadherin, NCAM and ICAM. The binding site on DMS53 surface for cFNGRQQc peptide need to be proven in the future.