Development and Use of Monoclonal Antibodies Against an Oncofetal Protein Associated with Carcinogenesis and Tumorigenesis

Abstract

An oncofetal protein (OFP) studied in our laboratory associated with embryogenesis, carcinogenesis and tumorigenesis has as its known biological function the modification of RNA release from isolated nuclei. In the present study, we have developed and investigated the use of monoclonal antibodies against OFP. Six hybridoma cell lines (A-F) were isolated by screening the hybridoma culture media for anti-OFP antibodies (MOFP) with an indirect ELISA and by testing the ability of these antibodies complexed with anti-mouse IgG-agarose to bind to rat OFP and remove its associated RNA transport activity from solution (Immunobioassay). An inhibition ELISA developed to measure OFP gave a linear response up to 20 ng of plasma protein from a tumor-bearing rat. Western blot analysis using these monoclonals showed that OFP from a rat tumor (H7777) cytosol that shed to the blood consisted of two species exhibiting molecular weights of 50 and 55 kD respectively. In order to show the usefulness of our assays, a preliminary study showing the ability of the immunobioassay to detect the expression of OFP in the plasma of carcinogen treated rats in a dosage dependent manner has been presented. Since OFP is produced in the target organ of rats shortly after treatment with carcinogens and persists in the preneoplastic foci and subsequent tumors, these monoclonal antibodies will be valuable in studying its involvement in chemical carcinogenesis and tumorigenesis.