Serine and proline-rich ligands enriched via phage-display technology show preferential binding to BCR/ABL expressing cells.
OBJECTIVE
Despite the use of targeted therapy, chronic myelogenous leukemia (CML) currently remains incurable with drug therapy, with patients requiring life-long treatment. Developing either a vaccine to prevent the disease or another novel drug to specifically target and eradicate the CML cell will require the identification of CML-associated cell-surface markers and molecules that can bind specifically to the cell surface. In an attempt to discover peptides that bind specifically to cells in the early chronic phase of the disease, we used phage-display technology to identify heptapeptides that bind specifically to the surface of BCR/ABL-expressing fibroblasts.


METHODS
An in vitro system using NIH3T3 stably transfected with pGD210 (BCR/ABL) was used as a model for the chronic phase of the disease. The cells were panned using a linear heptapeptide phage library (Ph.D 7.0) in a negative/positive panning strategy with NIH3T3 containing only the plasmid vector as the wild type control.


RESULTS
We identified four novel peptides that were enriched through this technique. These peptides contained either multiple proline residues or serine/threonine-proline pairs and showed a confirmed binding preference for BCR/ABL+ fibroblasts. The peptide Y-R-A-P-W-P-P also showed a binding affinity for granulocytes from untreated CML patients.


CONCLUSIONS
We have identified several novel peptides that can be used in future studies to identify specific CML cell-surface antigens or provide a novel drug-delivery mechanism.
National Health Laboratory Services (NHLS)/Groote Schuur Hospital, Haematology, Cape Town, South Africa; Division of Haematology, University of Cape Town, Cape Town, South Africa. Electronic address: karen.shires@uct.ac.za.
Karen
K
Shires
National Health Laboratory Services (NHLS)/Groote Schuur Hospital, Haematology, Cape Town, South Africa.
Iva
I
Shankland
Division of Haematology, University of Cape Town, Cape Town, South Africa.
Shaheen
S
Mowla
Division of Haematology, University of Cape Town, Cape Town, South Africa.
Samuel
S
Njikan
Division of Haematology, University of Cape Town, Cape Town, South Africa.
Jai
J
Jaymacker
Division of Haematology, University of Cape Town, Cape Town, South Africa.
Nicolas
N
Novitzky
D000595:Amino Acid Sequence; D000818:Animals; D061505:Cell Surface Display Techniques / Q000379:methods*; D002999:Clone Cells; D005347:Fibroblasts / Q000378:metabolism*; D016044:Fusion Proteins, bcr-abl / Q000378:metabolism*; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000378:metabolism*; D008024:Ligands; D051379:Mice; D008969:Molecular Sequence Data; D041681:NIH 3T3 Cells; D010455:Peptides / Q000737:chemistry; D011392:Proline / Q000378:metabolism*; D011485:Protein Binding; D016415:Sequence Alignment; D012694:Serine / Q000378:metabolism*; D014162:Transfection
D008024:Ligands; D010455:Peptides; D012694:Serine; D011392:Proline; D016044:Fusion Proteins, bcr-abl
BCR/ABL; CML; Cell-surface; Fibroblast; Phage-display