EFFECT OF LOCAL-ADMINISTRATION OF EPIDERMAL GROWTH-FACTOR ON 9,10-DIMETHYL-1,2 BENZANTHRACENE-INDUCED TUMOR-FORMATION IN HAMSTER-CHEEK POUCH

The effect of local administration of epidermal growth factor (EGF) on 9,10-dimethyl-1,2-benzanthracene (DMBA)-induced tumour formation was investigated in a hamster cheek pouch carcinogenesis model. DMBA-treat ed hamsters underwent either sialoadenectomy (groups 1 and 2) or a sha m operation (groups 3 and 4). Thereafter, EGF (groups 1 and 3) or vehi cle (groups 2 and 4) was applied to the cheek pouches for 6 weeks. Fou rteen weeks after the beginning of the experiment, the number of cheek pouch tumours was significantly greater in EGF-treated hamsters than in vehicle-treated hamsters, irrespective of whether the submandibular glands had been removed. The number of forestomach tumours, induced b y DMBA application to the cheek pouches, was also increased by EGF. Th ese results suggest that EGF applied from the luminal side of the muco sa stimulates tumour formation in the hamster cheek pouch and forestom ach.