ISOLATION OF P53 PROTEIN FROM THE SERUM OF COLON-CANCER AND NONCANCERPATIENTS

A new method for the isolation of p53 protein from the sera of cancer and non-cancer patients has been developed. The method is based on the utilization of a new modification of a support for affinity chromatog raphy in the form of gel fiberglass (GFG) (R. Zusman, patent applicati ons, Israel, 1992; USA 1993). The sera were percolated through GFG col umns with entrapped rabbit IgG generated against the colon cancer anti gens. Tumor-associated antigens were eluted from sera of cancer patien ts in large amounts, up to 2.4 mg/ml serum/column. Concentrations of t hese antigens in different sera and their affinity to anti-tumoral ant ibodies were detected by ELISA. Western immunoblotting with commercial monoclonal antibodies and SDS-PAGE identified the isolated antigens a s the p53 protein. This protein has been isolated in the highest conce ntration yet reported from the serum of cancer patients, up to 1 mg/ml . The same protein has been found in the serum of healthy people and n on-cancer patients but in significantly lower concentrations. Isolatio n of p53 protein from sera of noncancer patients confirms the opinion of some investigators that this protein should be considered not only as an oncogene but also as a protein correlated with different changes in the cell cycle.