Glycoproteins having lipid mobilising properties and therapeutic applications thereof

Abstract

A biologically active lipid mobilising agent for use in therapy is disclosed which has the properties and characteristics of a Zn-α 2 -glycoprotein, or of a fragment thereof having an apparent molecular mass M r greater than 6.0 kDa as determined by gel exclusion chromatography. Methods of isolation and purification from biological material are also disclosed together with uses of the material for making up pharmaceutical compositions, especially pharmaceutical compositions useful for treating mammals to achieve weight reduction or for controlling obesity. In addition, uses of the material for developing diagnostic agents and for identifying inhibitors of lipolytic activity for therapeutic purposes are disclosed.

What is claimed is: 
     
         1 . A diagnostic method for detecting the presence of a tumor in a mammal and/or for monitoring the progress of treatment of such a tumor, comprising taking from said mammal a sample of urine, blood serum or other body fluid, and testing to detect the presence of and/or to measure the amount therein of Zn-α 2 -glycoprotein. 
     
     
         2 . The diagnostic method of  claim 1 , wherein the testing comprises contacting Zn-α 2 -glycoprotein with a biochemical reagent that specifically recognizes and binds to Zn-α 2 -glycoprotein. 
     
     
         3 . The diagnostic method of  claim 2 , wherein the biochemical reagent is a monoclonal or polyclonal antibody. 
     
     
         4 . The diagnostic method of  claim 1 , which is applied to a sample of urine. 
     
     
         5 . A diagnostic kit for carrying out the method of  claim 1 , said kit comprising a receptacle for receiving the sample of body fluid, a biochemical reagent for detecting Zn-α 2 -glycoprotein, and instructions for use of said kit. 
     
     
         6 . A method for producing antibodies or antibody fragments that bind specifically to a lipid mobilizing agent having the properties and characteristics of a Zn-α 2 -glycoprotein, said method comprising subjecting an extract of a cachexia-inducing tumor or of a culture of a cachexia-inducing tumor yell line, or a sample of urine or other body fluid of a mammal bearing a cachexia-inducing tumor, to a combination of ion exchange, gel filtration size exclusion chromatography, and hydrophobic interaction chromatography, and recovering a single product or molecular species having an apparent relative molecular mass of 43 kDa, as determined by 15% SDS-PAGE electrophoresis, which is substantially free of proteolytic activity, and which is a lipid mobilizing agent having the properties and characteristics of a Zn-α 2 -glycoprotein; and preparing antibodies or antibody fragments that bind specifically to said lipid mobilizing agent. 
     
     
         7 . The method of  claim 6 , wherein the step of preparing antibodies comprises preparing polyclonal antibodies. 
     
     
         8 . The method of  claim 6 , wherein the step of preparing antibodies comprises preparing monoclonal antibodies. 
     
     
         9 . A method for treating cachexia in a cancer patient comprising administering to a patient in need of such treatment antibodies or antibody fragments that bind specifically to a lipid mobilizing agent which has an apparent molecular mass M r  greater than 6.0 kDa as determined by gel exclusion chromatography, which induces lipolysis in mammalian adipocytes, and which has the properties and characteristics of a Zn-α 2 -glycoprotein. 
     
     
         10 . The method of  claim 9 , wherein the Upid mobilizing agent is substantially free of proteolytic activity and consists essentially of a glycosylated polypeptide having an apparent relative molecular mass M r  of about 43 kDa as determined by its electrophoretic mobility when subjected to 15% SDS-PAGE electrophoresis, and has homology in amino acid sequence with the amino acid sequence (SEQ ID No: 1) of human plasma Zn-α 2 -glycoprotein. 
     
     
         11 . The method of  claim 9 , comprising administering monoclonal antibodies that bind specifically to the lipid mobilizing agent. 
     
     
         12 . The method of  claim 9 , comprising administering antibody fragments that bind specifically to the lipid mobilizing agent; wherein said antibody fragments are selected from the group consisting of F(ab′)2, Fab′, Fab, and Fv. 
     
     
         13 . A purified biologically active lipid mobilizing agent for use in therapy which has an apparent molecular mass M r  greater than 6.0 kDa as determined by its electrophoretic mobility when subjected to 15% SDS-PAGE electrophoresis gel exclusion chromatography, which induces lipolysis in mammalian adipocytes, and which has the properties and characteristics of a Zn-α 2 -glycoprotein. 
     
     
         14 . The purified lipid mobilizing agent of  claim 13 , which is substantially free of proteolytic activity and which consists essentially of a glycosylated polypeptide having an apparent relative molecular mass M r  of about 43 kDa as determined by its electrophoretic mobility when subjected to 15% SDS-PAGE electrophoresis, and having homology in amino acid sequence with the amino acid sequence (SEQ ID No: 1) of human plasma Zn-α 2 -glycoprotein. 
     
     
         15 . The purified lipid mobilizing agent of  claim 14 , which is obtainable by a process that includes sequential steps of subjecting biological material to ion exchange chromatography, exclusion chromatography, and then to hydrophobic interaction chromatography, wherein said biological material is urine from a cancer cachexia patient or an extract of a culture of a MAC 16 tumor cell line deposited under the provisions of the Budapest Treaty in the European Collection of Animal Cell Cultures (ECACC) under an Accession No. 89030816. 
     
     
         16 . A composition comprising a therapeutically effective amount of the lipid mobilizing agent of  claim 14 , and a pharmaceutically acceptable carrier, diluent or excipient. 
     
     
         17 . A method of treating a mammal to bring about a weight reduction or reduction in obesity, comprising administering to a mammal in need of such treatment a therapeutically effective dosage of the lipid mobilizing agent of  claim 14 .