Effect of epidermal growth factor administration on the development of mouse salivary gland carcinomas

This study investigated whether epidermal growth factor (EGF) administratio n was capable of modifying salivary gland carcinogenesis. Two groups of mic e were given 1 mg of 9,10-dimethyl-1,2-benzanthracene (DMBA) into the left submandibular gland, and then Group 1 mice received 2 mu g of EGF and Group 2 mice received vehicle subcutaneously for 8 weeks. Mice in two other grou ps, 3 and 4, received either EGF or vehicle alone. Twelve weeks after the s tart of the experiment, the incidences of submandibular gland carcinomas in Groups I and 2 were 39% and 58%, respectively, although this difference wa s not statistically significant. Duct- and cyst-like structures and carcino mas in the left submandibular glands were weakly stained by anti-EGF recept or (EGFR) antibody. Immunoblot and reverse transcriptase polymerase chain r eaction (RT-PCR) analyses revealed the expression of EGFR in the submandibu lar glands and carcinomas. However, EGFR was undetectable in YT cells that were derived from a submandibular gland undifferentiated carcinoma of a Gro up 2 mouse. These findings indicate that EGF does not promote tumor inducti on in mouse salivary gland carcinogenesis. This may be ascribed in part to the low expression level of EGFR in tumor cells.