Fig. 1.

HPV16 oncogenes can induce DNA synthesis in the normally quiescent compartment of oral and esophageal epithelia. Adult mice (7 weeks old) were injected with the nucleotide analog BrdU 1 h before euthanasia. The tongue and esophagus were harvested from each mouse, fixed, and embedded in paraffin. BrdU-specific immunohistochemistry was performed on slides containing sections of tongue (A and B) and esophagus (C and D) from nontransgenic (A and C) and K14E6/K14E7-transgenic (B and D) mice. The results from three animals of each genotype were quantified (suprabasal positive nuclei/total nuclei) (E). In both the tongue and esophagus of HPV16-transgenic mice (E6E7), the increase in suprabasal DNA synthesis compared with that seen in nontransgenic (NTG) counterparts was statistically significant (P = 0.02; Wilcoxon rank-sum test).