Inducible nitric oxide synthase mRNA is upregulated in skin tumors of v- Ha-ras transgenic TG-AC mice treated with 12-o-tetradecanoylphorbol-13- acetate

The correlation between the steady-state level of inducible nitric oxide synthase (iNOS) mRNA and skin tumors induced following treatment with 12-o- tetradecanoylphorbol-13-acetate (TPA) was investigated in transgenic TG-AC mice, which carry the v-Ha-ras oncogene fused to the promoter of the mouse embryonic α-like, ζ-globin gene. In animals treated with TPA (2.5 μgX2/week, for 2 weeks), the increase of iNOS mRNA was locally confined only to the regions of papillomas, but not to the skin tissues surrounding the papillomas. However, the tissues surrounding the papillomas showed only a minor increase in the steady-state level of iNOS mRNA. These data suggest that iNOS gene expressions may underlie tumorigenesis during TPA promotion in TG-AC mice.