In vitro targeted killing of prostate tumor cells by a synthetic amoebapore helix 3 peptide modified with two gamma-linked glutamate residues at the COOH terminus.
Prostate-specific membrane antigen (PSMA) is a trans-membrane protein specifically expressed in LNCaP cells, malignant human prostate tissues, and the surrounding neovasculature. PSMA is a unique exopeptidase with reactivity toward poly-gamma-glutamated folates. It can sequentially remove the poly-gamma-glutamyl termini. To target prostate tumor cells, a novel procytolytic peptide was designed with a backbone consisting of an amoebapore H3 domain modified by two gamma-linked glutamate residues at the epsilon-amino group of the COOH-terminal lysine residue. The strategy behind the design of this prolytic peptide was to inactivate the lytic amoebapore H3 peptide by replacing its functionally important COOH-terminal positive charge with negatively charged groups, which in turn might be selectively removed by the PSMA exopeptidase. This peptide exhibited little cytolytic activity toward PSMA-negative cells, such as PC-3 cells. On the other hand, this peptide exhibited strong cytolytic activity toward PSMA-positive LNCaP cells in a concentration-dependent manner. The carboxypeptidase inhibitor 4,4'-phosphonicobis (butane-1,3-dicarboxylic acid) can inhibit this activity. Moreover, this peptide also exhibited cytolytic activity toward PSMA cDNA-transfected PC-3 cells.
Warren
P
P
Oncology Research Institute of the Greenville Hospital System, Greenville, South Carolina 29605, USA.
Li
L
L
Song
W
W
Holle
E
E
Wei
Y
Y
Wagner
T
T
Yu
X
X
D000595:Amino Acid Sequence; D000954:Antigens, Surface; D002268:Carboxypeptidases / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D043425:Glutamate Carboxypeptidase II; D018698:Glutamic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D006801:Humans; D007473:Ion Channels; D008297:Male; D008565:Membrane Proteins / Q000138:chemical synthesis / Q000494:pharmacology*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000494:pharmacology*; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000276:immunology; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D015800:Protozoan Proteins / Q000138:chemical synthesis / Q000494:pharmacology*
D000954:Antigens, Surface; D007473:Ion Channels; D008565:Membrane Proteins; D010446:Peptide Fragments; D015800:Protozoan Proteins; C041670:amoebapore proteins, protozoan; D018698:Glutamic Acid; D002268:Carboxypeptidases; C473848:FOLH1 protein, human; D043425:Glutamate Carboxypeptidase II