Tissue Context Shapes Distinct Premalignant Outcomes in an HPV16 E6/E7-Mutant Pik3ca Transgenic Mouse Model.

High-risk human papillomavirus (HPV) infection, particularly HPV16, is a major etiologic factor associated with multiple human cancers, including anal, cervical, and oropharyngeal carcinomas. However, the mechanisms underlying tissue-specific responses to HPV oncogene expression remain poorly understood. In this study, we developed and characterized a double-inducible transgenic mouse model enabling spatially and temporally controlled expression of HPV16 E6/E7 oncoproteins in K14-positive epithelial progenitor cells of both the anal and oral mucosae. Within 2 months of induction, HPV16 E6/E7 expression elicited epithelial hyperplasia and dysplasia in both tissues but with distinct outcomes: low-grade squamous intraepithelial lesions in the anal canal and moderate to severe dysplasia in the tongue. Continuous oncogene expression was required for lesion maintenance, as doxycycline withdrawal reversed the proliferative phenotype, indicating a dynamic and reversible process. To assess whether activation of the PI3K pathway could cooperate with HPV oncogenes, we combined the E6/E7 model with a Pik3caH1047R knock-in mouse line. Constitutive PI3K activation alone induced mild dysplasia in both epithelia, whereas its combination with E6/E7 enhanced dysplastic severity in the tongue but not in the anal mucosa. No progression to invasive carcinoma was observed within 6 months. These findings demonstrate that identical oncogenic signals-HPV16 E6/E7 expression and PI3K activation-produce distinct premalignant outcomes depending on epithelial context. This work highlights the critical role of local microenvironmental factors in HPV-driven carcinogenesis and provides a platform to identify tissue-specific therapeutic vulnerabilities in HPV-associated cancers. SIGNIFICANCE: This work presents a double-inducible mouse model showing that HPV16 E6/E7 and PI3K activation drives distinct dysplastic outcomes in anal and oral epithelia. The study highlights how tissue context and microenvironment critically shape HPV oncogene effects, offering an important tool for uncovering mechanisms and therapeutic targets in HPV-related cancers.