Neuroblastoma tumor cell-binding peptides identified through random peptide phage display

Random peptide phage display libraries have been employed widely to identif y protein-protein interactions, using as targets either purified proteins, intact cells, or organs. To isolate peptides that bind to human neuroblasto ma cells, we have used a phage display approach with the neuroblastoma cell line WAC 2 as the target. In particular, two bacteriophages, t147 and t160 , displaying peptides p147 and p160. respectively. were isolated by repeate d display cycles. Binding of t147 and t160 to WAC 2 cells was abrogated by pretreatment with the peptides p147 and p160, respectively, which strongly support that cellular binding of both phages is dictated by their displayed peptides. Immunofluorescence analysis by confocal light microscopy reveale d that the major proportion of t147 remains on the surface of WAC 2 cells a nd that only a fraction is taken up into the cells. In contrast, the vast m ajority of t160 is internalized. K+ depletion reduced the number of the pha ges internalized by the cells to approximately 20% for t160 and to 10% for t147, indicating that the phage internalization was through receptor-mediat ed endocytosis. Phage t147 appears to bind to a range of tumor cell lines, including neuroblastoma, breast cancer, glioblastoma and C-cell carcinoma. but less so to non-tumor lines, such as erythrocytes, lymphocytes, monocyte s and epithelial cells. Phage t160 bound to a range of neuroblastoma cell l ines and a breast cancer cell line, but not to other tested cell lines. Whi le neither of the displayed peptides conferred a narrow tissue specific bin ding ability, they do provide a basis for targeted drug delivery in selecte d experimental or natural tumor systems. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.