Inhibition of 3H-TdR uptake for Human Gastric Carcinoma Cells by Epidermal Growth Factor Specific Antibody

This study examined whether human gastric carcinoma cells produced EGF for self-stimulation, using TMK-1 and MKN-28 cells which express mRNA for EGF and EGF receptor. EGF protein production was confirmed by ELISA and flow cytometric analysis. The lysates of these cells replaced EGF-induced biological activity to EGF receptor bearing KB cells but the culture supernatants did not. Furthermore, EGF-radioreceptor assay revealed non-secretion of EGF product. EGF specific monoclonal antibody neutralized exogenous EGF-induced 3H-TdR uptake, and inhibited spontaneous 3H-TdR uptake of TMK-1 and MKN-28 cells. These results suggest that EGF specific antibody binds to EGF protein at the cell surface, leading to the inhibition of 3HTdR uptake, and that EGF produced by tumor cells may act as an autocrine growth factor in human gastric carcinoma cells.