Combinatorial evolution of high-affinity peptides that bind to the Thomsen-Friedenreich carcinoma antigen.
Thomsen-Friedenreich (TF) antigen occurs on approximately 90% of human carcinomas, is likely involved in carcinoma cell homotypic aggregation, and has clinical value as a prognostic indicator and marker of metastasized cells. Previously, we isolated anti-TF antigen peptides from bacteriophage display libraries. These bound to TF antigen on carcinoma cells but were of low affinity and solubility. We hypothesized that peptide amino acid sequence changes would result in increased affinity and solubility, which would translate into improved carcinoma cell binding and increased inhibition of aggregation. The new peptides were more soluble and exhibited up to fivefold increase in affinity (Kd approximately equal to 60 nM). They bound cultured human breast and prostate carcinoma cells at low concentrations, whereas the earlier peptides did not. Moreover, the new peptides were potent inhibitors of homotypic aggregation. The maturated peptides will have expanded applications in basic studies of the TF antigen and particular utility as clinical carcinoma-targeting agents.
Landon
Linda A
LA
Department of Biochemistry, M121 Medical Sciences Bldg., University of Missouri, Columbia, Missouri 65212, USA.
Peletskaya
Elena N
EN
Glinsky
Vladislav V
VV
Karasseva
Natalia
N
Quinn
Thomas P
TP
Deutscher
Susan L
SL
D000595:Amino Acid Sequence; D000906:Antibodies / Q000737:chemistry / Q000276:immunology*; D000915:Antibody Affinity; D000918:Antibody Specificity; D000951:Antigens, Neoplasm / Q000276:immunology*; D015295:Antigens, Tumor-Associated, Carbohydrate / Q000276:immunology*; D001435:Bacteriophages / Q000235:genetics* / Q000276:immunology; D001943:Breast Neoplasms; D002448:Cell Adhesion / Q000276:immunology; D002449:Cell Aggregation / Q000276:immunology; D002462:Cell Membrane / Q000276:immunology; D005260:Female; D005456:Fluorescent Dyes; D006801:Humans; D008297:Male; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D019151:Peptide Library; D010455:Peptides / Q000037:antagonists & inhibitors / Q000138:chemical synthesis* / Q000276:immunology; D011471:Prostatic Neoplasms; D014407:Tumor Cells, Cultured
D000906:Antibodies; D000951:Antigens, Neoplasm; D015295:Antigens, Tumor-Associated, Carbohydrate; D005456:Fluorescent Dyes; D019151:Peptide Library; D010455:Peptides; C016467:Thomsen-Friedenreich antigen