Modified plasminogen activator inhibitor type-1 and methods based thereon

Abstract

The present invention is based upon the discovery that modified plasminogen activator inhibitor type-I (PAI-1) in which two or more amino acid residues that do not contain a sulfhydryl group have been replaced with amino acid residues that contain a sulfhydryl group and, therefore, forms intramolecular disulfide bonds, have increased in vivo half-life. Also disclosed are the modified PAI-1 proteins, derivatives and analogs thereof, specific antibodies, nucleic acid molecules and host cells. Methods for producing modified PAI-1, derivatives and analogs are also provided. The invention further relates to Therapeutics, pharmaceutical compositions and method of using the composition for treatment. The invention may be used to inhibit angiogenesis in a subject, thereby treating diseases or conditions associated with undesired angiogenesis and cell proliferation. Such conditions include psoriasis, chronic inflammation, tumor invasion and metastasis and conditions in which angiogenesis is pathogenic. The modified PAI-1 molecules of the present invention are useful for the treatment, prophylaxis, management and amelioration of cardiovascular diseases such as, but not limited to those that are related to hyperfibrinolysis, hemophilia, and vessel leakage syndrome.

Description

[0001]The invention was made with Government support under Department of Defense DAMD 17-01-1-0553. The government has certain rights in the invention.1. FIELD OF THE INVENTION[0002]The present invention relates to modified plasminogen activator inhibitor type-1 (PAI-1), and derivatives and analogs thereof, in which two or more amino acid residues that do not contain a sulfhydryl group have been replaced with amino acid residues that contain a sulfhydryl group so that intramolecular disulfide bonds can be formed. These modified PAI-1 molecules, and derivatives and analogs thereof, have increased in vivo half-life of the active form of PAI-1. Also disclosed are peptides of such modified proteins, antibodies that specifically bind the PAI-1 molecules, derivatives and analogs thereof, nucleic acid molecules, particularly DNA, encoding the modified proteins, and host cells containing such nucleic acids. Methods for producing modified PAI-1, and derivatives and analogs thereof are also p...

AI Technical Summary

Benefits of technology

[0021]The present invention is based upon the observation of the present inventors that a modified PAI-1 protein in which two or more amino acid residues that do not contain a sulfhydryl group have been replaced with amino acid residues that contain sulfhydryl groups such as, but not limited to, cysteine residues, that form one or more intramolecule disulfide bonds, has a much longer in vivo half-life of the active form of PAI-1 than a wild-type PAI-1 protein, in which there is no such disulfide bond or other introduced stabilizing modification (Chorostowska-Wynimko et al., 2003, Molecular Cancer Therapeutics 2:19-28). These modified PAI-1 proteins are generated by amino acid substitutions of certain amino acid residues with cysteine residues to produce disulfide bridges linking the A3 strand and the A5 strand of the g-sheet of the PAI-1 protein (see FIG. 6). The mutations introduced into the PAI-1 protein do not significantly reduce the PAI-1 enzymatic activity (or does not reduce the enzymatic activity to an extent that is not compensated by the increase in in vivo half-life) but can increase the half-life of the active form of the modified PAI-1 when compared to wild-type PAI-1.

[0022]Inhibitors of urokinase plasminogen activator (uPA) strongly suppress angiogenesis and consequently limit cancer growth. The majority of known small-molecular inhibitors of uPA are toxic and nonspecific, while plasminogen activator inhibitor type 1 (PAI-1) is non-toxic and highly specific for uPA. Unfortunately, PAI-1 converts to a latent, inactive form with a half-life (t1 / 2) of approximately 2 hrs. The present invention is aimed at providing modified PAI-1 proteins (and functionally active fragments, derivatives and analogs thereof) (“collectively, “modified PAI-1 molecules”) with increased in vivo half-life of the active form of modified PAI-1 (as determined, for example, in Section 5.6), and preferably, with increased binding to uPA. By introducing amino acid residues that contain a sulfhydryl group into the PAI-1 polypeptide such that intramolecular disulfide bonds are formed, the t1 / 2 of PAI-1 can be extended to therapeutically desired values.

[0027]The present invention relates to modified PAI-1 molecules having one or more substitutions, deletions or insertions of amino acid residues or other mutations (as described hereinbelow) to increase in vivo half-life of the active form of the PAI-1 molecules. In preferred embodiments, modified PAI-1 molecules of the invention are more active than wild-type PAI-1 protein in binding uPA and also have prolonged half-life of the active form of the modified PAI-1 molecules in circulation.

Problems solved by technology

Metastasis is the cause of most cancer-related deaths.

Although uPA inhibitors have been implicated in induction of tumor cell growth, most known uPA inhibitors are unstable, weak or toxic in humans.

This conversion represents a major challenge in the process to purify, conjugate and store large quantities of active PAI-1 or its conjugates.

Unfortunately, the PAI-1 spontaneously reverses to its latent form again, as quickly as described above.

In general, although theoretically useful in the treatment of cancer and other conditions, uPA inhibitors are toxic or labile.

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