Carcinoembryonic antigen release from colorectal cancer cells in tissue culture

Abstract

Limited data are available concerning the physicochemical and immunological characteristics of carcinoembryonic antigen spontaneously released from cancer cells in tissue culture. The Hoffman—LaRoche Z-gel assay for the detection of circulating carcinoembryonic antigen (CEA) in serum was modified for the detection of CEA in tissue culture supernatants. A number of mycoplasma free epithelial lines established from colorectal cancer specimens were evaluated for cell-bound and spontaneously released CEA. Further studies were performed using tissue culture supernatants from colon cancer line SW480, which spontaneously released microgram quantities of CEA into the cell culture supernatant. By competitive inhibition analysis this CEA appeared identical with the Roche CEA standard. Gel filtration studies on Sephadex G-200 and affinity chromatography with concanavalin A sepharose-4B revealed the supernatant CEA and the Roche standard to be similar. These data suggest that this system offers potential for further characterization of this oncofetal protein and for study of its biosynthesis and “spontaneous” release from cancer cell surface. The molecular basis of such activity on the genetic level would have significant importance in basic biological studies of malignant transformation.