Stimulation by EGF of the growth of EGF receptor-hyperproducing tumor cells in athymic mice.

EGF receptor-hyperproducing cells of squamous carcinoma origin were inoculated s.c. into the bilatero-abdominal regions of athymic mice and a mini-osmotic pump containing EGF was implanted on teh back. After 2 weeks the tumors formed from 5 different cell lines in the presence of EGF weighed 3 to 6 times more than those formed in the absence of EGF. The cells recovered from these tumors maintained their original characteristics such as the amplified EGF receptor gene, high numbers of EGF receptors and a sensitivity to EGF-mediated inhibition of growth in vitro. These results suggest that EGF plays an important role in promoting growth of squamous-cell carcinoma in vivo.