Development and characterization of potent and specific peptide inhibitors of p60c-src protein tyrosine kinase using pseudosubstrate-based inhibitor design approach.
The cytoplasmic protein p60c-src, an ubiquitous non-receptor protein tyrosine kinase (PTK) is a potential anticancer target as it is over-expressed and/or constitutively active in several cancer types. In addition, the phenotype of c-src knock-out mice is consistent with osteopetrosis, which suggests that inhibitors against this enzyme may also be therapeutic for osteoporosis. Using a known peptide substrate for c-src, MIYKYYF, as a template, we have developed a series of pseudosubstrate-based peptide inhibitors. Structure-activity relationship studies have been performed on one of these inhibitors, CIYKYYF. In a kinase assay using YIYGSFK as the substrate, CIYKYY has been demonstrated to inhibit p60c-src, with an IC50 of 0.6 microm. Further truncation has led to the determination that even the smaller peptide, CIYK, is a moderately potent inhibitor with IC50 of 15 microm. Some improvement in inhibitory potency (IC50 = 11.8 microm) has been observed with the replacement of Tyr3 in CIYK with beta-phenylalanine (beta-Phe). The tetrapeptide CI(beta-Phe)K will be used as a lead compound for future development of peptidomimetics and small molecule inhibitors that have the capacity to penetrate the plasma membrane of intact cells.
Kamath
J R
JR
Division of Hematology and Oncology, Department of Internal Medicine, UC Davis Cancer Center, University of California Davis, 4501 X Street, Sacramento, CA 95817, USA.
Liu
R
R
Enstrom
A M
AM
Lou
Q
Q
Lam
K S
KS
D000595:Amino Acid Sequence; D015195:Drug Design; D004791:Enzyme Inhibitors / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D006801:Humans; D020128:Inhibitory Concentration 50; D008969:Molecular Sequence Data; D015394:Molecular Structure; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D010455:Peptides / Q000737:chemistry* / Q000378:metabolism*; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
D004791:Enzyme Inhibitors; D010446:Peptide Fragments; D010455:Peptides; D016392:Proto-Oncogene Proteins pp60(c-src)