p63 expression is associated with p53 loss in oralesophageal epithelia of p53-deficient mice

The p53 gene family, comprising p53, p63, and p73, has overlapping and distinctive functional roles. These members share structural similarities allowing for dynamic interplay in the activation of genes that are impor-tant in development and key cellular functions, such as the induction of apoptosis. Whereas p53 is a classical tumor suppressor gene, p63 and p73 do not share this feature in cancer formation and progression. The compensation in the expression level of these members in a background that is deficient for one of them has not been examined previously. Given the importance of p63 in the development and differentiation of oral-esophageal stratified squamous epithelia and the absence of oral-esopha-geal tumors in p53-null mice, we postulated and describe herein that p63 expression is associated with the loss of p53 in a p53-deficient background. Both full-length and amino-truncated forms of p63 are expressed and increased in oral-esophageal epithelia of p53-null mice when compared with wild-type mice, and the induction of p21 may potentially be pre-served through the increase of p63