Spontaneous SCC induced by the somatic inactivation of Rb1 and Trp53 tumor suppressors in mouse stratified epithelia. Mus musculus

The squamous cell carcinomas represent the aggressive type of non melanoma skin cancer, the most frequent malignancy among human population. We have studied here the possible relationship between these two pathways in skin using epidermal-specific mutant mice. Loss of p53, but not pRb, produces spontaneous tumor development, indicating that, contrary to pRb, p53 is the predominant tumor suppressor acting in mouse epidermis. The simultaneous inactivation of pRb and p53 does not aggravate the epidermal phenotype observed in Rb-deficient mice in terms of proliferation and/or differentiation. However, in doubly deficient mice spontaneous skin tumor development is severely accelerated. The tumors are aggressive, undifferentiated and display a hair follicle origin. Detailed analysis indicates that the acceleration is mediated by premature activation of the EGFR/Akt pathway, resulting in increased angiogenesis. The molecular characteristics of this model provide valuable tools to understand epidermal tumor formation, and may ultimately contribute to the development of therapies for the treatment of aggressive squamous cancer. Keywords: Squamous cell carcinoma, Epidermis, Tumorigenesis, pRb, p53, Akt, Angiogenesis Overall design: Pools from RNA whole skin extracts from 3 animals of same genotype were done and analyzed, per duplicate, in mouse microarrays. Comparison was performed between the 4 different genotypes.