[Tumor suppressor gene p53--function and significance in gastroenterology]

The p53 gene is a tumor suppressor gene. The encoded p53 protein directly induces the expression of genes that are involved in cell cycle regulation. p53 was named "guardian of the genome" for its prevention of an otherwise fatal outcome under DNA damaging conditions. Under these conditions p53 inhibits cell cycle progression or induces apoptosis. The p53 protein has been structurally and functionally divided into four domains, two of which are of crucial importance: The sequence specific DNA-binding domain and the aminoterminal transactivation domain. They are both required to trigger the downstream processes following p53 expression. Mutations and inactivation of p53 by oncogenes are frequent events in the development of human neoplasia. That includes gastrointestinal tumors with their mutational spectra reflecting tissue-specific influences of endogenous and exogenous factors in carcinogenesis. Despite considerable progress in molecular biology, clinical applicability of p53 in both diagnostic and therapeutic strategies has not yet been validated.