EPIDERMAL GROWTH-FACTOR AND TRANSFORMING GROWTH-FACTOR-ALPHA CHARACTERISTICS OF HUMAN ORAL-CARCINOMA CELL-LINES

This study examined the expression of epidermal growth factor (EGF) ce ll-surface receptors, the response to exogenous ligand and the autocri ne production of transforming growth factor a (TGF-a) in normal and ca rcinoma-derived human oral keratinocytes. One of eight malignant cell lines overexpressed EGF receptors, while the remainder expressed recep tor numbers similar to normal cells. Exogenous EGF stimulated incorpor ation of tritiated thymidine in a dose-dependent manner. In keratinocy tes expressing normal numbers of EGF receptors, the cellular response to exogenous EGF correlated positively with total EGF receptor number. SCC-derived keratinocytes produced more TGF-a than normal cells. Ther e was no statistical correlation between the autocrine production of T GF-a, EGF cell-surface receptor expression and cellular response to ex ogenous EGF. While the growth-stimulatory effects of exogenous TGF-cl were inhibited by the addition of a neutralising antibody, the presenc e of this antibody in conditioned medium failed to produce a similar d ecrease in growth. The results indicate that overexpression of EGF rec eptors is not an invariable characteristic of human oral squamous carc inoma-derived cell lines. Further, the contribution of TGF-a to the gr owth of normal and carcinoma-derived human oral keratinocytes in vitro may be less significant than previously documented.