Transgenic Mice Overexpressing Protein Kinase C Epsilon in Their Epidermis Exhibit Reduced Papilloma Burden but Enhanced Carcinoma Formation After Tumor Promotion

The study investigated the role of protein kinase C epsilon (PKCepsilon) in skin tumor development using transgenic mice that overexpressed PKCepsilon in their epidermis. Three independent mouse lines were created, with line 215 showing the highest PKCepsilon activity. These mice exhibited skin changes, including dryness, hair loss, and inflammation, progressing to hyperproliferation and ulceration. When subjected to a tumor promotion protocol, these mice showed a significant reduction (95-96%) in papilloma burden compared to wild-type controls. However, they developed carcinomas rapidly, which appeared to form independently of prior papilloma development. The findings suggested that PKCepsilon played a crucial role in regulating skin tumor development, reducing papilloma formation but enhancing carcinoma progression.