Identification of a met-binding peptide from a phage display library.
OBJECTIVE
Aberrant c-Met expression has been implicated in most types of human cancer. We are developing Met-directed imaging and therapeutic agents.


METHODS
To seek peptides that bind specifically to receptor Met, the Met-expressing cell lines S114 and SK-LMS-1 were used for biopanning with a random peptide phage display library. Competition ELISA, fluorescence-activated cell sorting analysis, an internalization assay, and a cell proliferation assay were used to characterize a Met-binding peptide in vitro. To evaluate the utility of the peptide as a diagnostic agent in vivo, 125I-labeled peptide was injected i.v. into nude mice bearing s.c. xenografts of the Met-expressing and hepatocyte growth factor (HGF)/scatter factor-expressing SK-LMS-1/HGF, and total body scintigrams were obtained between 1 and 24 h postinjection.


RESULTS
One Met-binding peptide (YLFSVHWPPLKA), designated Met-pep1, reacts with Met on the cell surface and competes with HGF/scatter factor binding to Met in a dose-dependent manner. Met-pep1 is internalized by Met-expressing cells after receptor binding. Met-pep1 inhibits human leiomyosarcoma SK-LMS-1 cell proliferation in vitro. In SK-LMS-1 mouse xenografts, tumor-associated activity was imaged as early as 1 h postinjection and remained visible in some animals as late as 24 h postinjection.


CONCLUSIONS
Met-pep1 specifically interacts with Met: it is internalized by Met-expressing cells and inhibits tumor cell proliferation in vitro; it is a potential diagnostic agent for tumor imaging.
Zhao
Ping
P
Laboratories of Antibody Technology, Van Andel Research Institute, Grand Rapids, Michigan and Nuclear Medicine Service, Department of Veterans Affairs Healthcare System, Ann Arbor, Michigan 49503, USA.
Grabinski
Tessa
T
Gao
Chongfeng
C
Skinner
R Scot
RS
Giambernardi
Troy
T
Su
Yanli
Y
Hudson
Eric
E
Resau
James
J
Gross
Milton
M
Vande Woude
George F
GF
Hay
Rick
R
Cao
Brian
B
D000818:Animals; D049109:Cell Proliferation; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D015972:Gene Expression Regulation, Neoplastic; D017228:Hepatocyte Growth Factor / Q000378:metabolism; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D041681:NIH 3T3 Cells; D009368:Neoplasm Transplantation; D019151:Peptide Library; D010455:Peptides / Q000737:chemistry; D019859:Proto-Oncogene Proteins c-met / Q000378:metabolism*
D019151:Peptide Library; D010455:Peptides; D017228:Hepatocyte Growth Factor; D019859:Proto-Oncogene Proteins c-met