Induction of interleukin-6 in the epidermis of mice in response to tumor-promoting agents

Recent reports imply that several epidermal cytokines have a functional role in the tumor promotion stage of the multistage carcinogenesis model in mouse dorsal skin. In this report we describe studies to assess the role of interleukin-6 (IL-6) in tumor promotion. Promoting, as well as non-promoting, hyperplastic agents were found to induce IL-6, as measured by mRNA expression. Inhibitors of tumor promotion inhibited tumor-promoter-mediated IL-6 induction. However, when mice were injected with a neutralizing antibody specific to murine IL-6, there was no effect on tumor-promoter-mediated epidermal hyperplasia and dermal inflammation. These studies suggest that even though IL-6 is produced in the epidermis following tumor promoter application, it does not modulate epidermal hyperplasia and dermal inflammation. Our findings also stress the importance of assessing, in in vivo studies, the function of those cytokines suggested by in vitro experiments to have important roles in tumor promotion.