Modification of tumor-associated antigen (CEA) expression of human lung cancer cells by irradiation, either alone or in combination with interferon-γ

The effect of irradiation either alone or in combination with cytokine (IFN- gamma) on the expression of carcinoembryonic antigen (CEA) on the surface of the human lung cancer cell line, GLL-1, was studied in vitro. The results demonstrated that CEA expression on GLL-1 cells increased after irradiation with a single dose of 10 Gy. In a time-course study the peak of CEA expression was observed at the 4th day after irradiation. The relative CEA expression on the 1st to 5th day after irradiation were 2.2, 1.2, 1.2, 1.4 and 1.3, respectively. Irradiation in combination with IFN-gamma showed an additional effect on the expression of CEA. A 1.7 fold increase in CEA expression was detected. A cell cycle study showed that the change in the relative CEA expression of the G(1) cell fraction was similar to that of all cell fractions. The relative CEA expression of GLL-1 cells treated by irradiation in combination with IFN- gamma in the G1 cell fraction was much higher than those treated differently.