A transgenic mouse model with cyclin D1 overexpression results in cell cycle, epidermal growth factor receptor, and p53 abnormalities.

The cyclin D1 oncogene is critical in the progression of the cell cycle through the G1 phase. It is frequently overexpressed in squamous cell carcinomas originating from the head/neck and esophagus. Yet, the functional consequences of aberrant cyclin D1 overexpression are not entirely understood apart from increased cell proliferation. To address this question, we have developed a transgenic mouse model in which the EBV ED-L2 promoter targets cyclin D1 to the stratified squamous epithelium in a tissue-specific fashion to the tongue and esophagus, thereby resulting in a dysplastic phenotype. We now demonstrate that the dysplastic phenotype is associated with increased cell proliferation based on proliferating cell nuclear antigen overexpression and abnormalities in cyclin-dependent kinase 4, epidermal growth factor receptor, and p53. In aggregate, these studies suggest that alterations in certain oncogenes and tumor suppressor genes occur early during head/neck and esophageal carcinogenesis.