Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.7 (plasmin)
 9,023 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Many tumors contain elevated levels of plasminogen activator and thus produce elevated levels of the protease plasmin in the milieu of the tumor. We have hypothesized, therefore, that it should be possible to prepare peptidyl prodrug derivatives of anticancer drugs that would be locally activated by tumor-associated plasmin. As an initial test of this hypothesis, we synthesized the peptidyl prodrugs of the anticancer drugs (alpha S, 5S)-alpha-amino-3-chloro-4,5-dihydro-5-isoxazoleacetic acid (acivicin, AT-125) and N,N-bis(2-chloroethyl)-p-phenylenediamine (phenylenediamine mustard) by mixed anhydride coupling of the parent drug with the protected tripeptide, Boc-D-Val-Leu-Lys(Boc)-OH, followed by deprotection with trifluoroacetic acid. The prodrugs showed an increased selective in vitro cytotoxicity for Rous sarcoma virus transformed chicken embryo fibroblasts (which produce elevated levels of plasminogen activator) compared to nontransformed fibroblasts (which produce low levels of plasminogen activator). In the presence of the plasmin inhibitor, p-nitrophenyl p'-guanidinobenzoate at 2 micrograms/mL, the selectivity of the phenylenediamine mustard prodrug was reduced, but there was no effect on the cytotoxicity of the free drug. Furthermore, the prodrug analogue D-valylleucyl-D-lysylphenylenediamine mustard (in which L-Lys has been replaced by D-Lys) was inactive. Finally, the prodrug derivative of acivicin did not display selective toxicity for transformed cells when the cells were cultured in plasminogen-free medium. These results suggest that plasmin hydrolysis is necessary for the activation of the prodrugs. The prodrugs were tested in vivo for antitumor activity. The prodrug of acivicin, like acivicin itself, was inactive against the B16 melanoma, a murine tumor that produces high levels of plasminogen activator. This prodrug was active against the M5076 carcinoma, a tumor that displays only moderate levels of plasminogen activator; however, despite the fact that the prodrug was 2- to 3-fold less toxic on a molar basis than acivicin, there was no evidence of an increased therapeutic index. The prodrug of phenylenediamine mustard was also slightly less toxic than the parent drug, but again there was no evidence for an improved therapeutic index against the B16 tumor.
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PMID:Plasmin-activated prodrugs for cancer chemotherapy. 1. Synthesis and biological activity of peptidylacivicin and peptidylphenylenediamine mustard. 622 Oct 99

Many types of malignant cells and human tumors display increased concentrations of the protease plasminogen activator that converts plasminogen to the highly active protease, plasmin. Because plasmin rapidly cleaves various low molecular weight compounds coupled to appropriate peptide specifiers, we hypothesized that coupling of such peptide specifiers to anticancer drugs might create "prodrugs" which would be locally activated by tumor-associated plasmin and consequently would be less toxic to normal cells. To provide an initial test of this concept we have synthesized peptidyl prodrugs of the structure D-Val-Leu-Lys-X in which the peptidyl portion has been designed to allow the prodrug to serve as an excellent plasmin substrate and X is an anticancer drug-either the glutamine analog (alphaS,5S) alpha-amino-3-chloro-4,5-dihydro-5-isoxazole-acetic acid (AT-125) or the alkylating agent N,N-bis(2-chloroethyl)-p-phenylenediamine (phenylenediamine mustard). Treatment of these prodrugs with plasmin generated the free peptide and the free drug, demonstrating that these prodrugs are plasmin substrates. The prodrugs and free drugs were tested in an in vitro system against either normal chicken embryo fibroblasts, which display a low level of plasminogen activator, or their virally transformed counterparts, which produce high levels of plasminogen activator. In each case the peptidyl prodrugs displayed at least a 5-fold increase in selectivity for the transformed cells compared to the free drug. The greater selectivity of action of the peptidyl prodrugs against transformed cell cultures suggests that these or similar prodrugs that are substrates for tumor-associated proteases may show increased therapeutic effectiveness in the treatment of tumors that produce sufficiently increased amounts of plasminogen activator.
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PMID:Protease-activated "prodrugs" for cancer chemotherapy. 624 27