REGULATION OF P53 PROTEIN EXPRESSION IN HUMAN BREAST-CANCER CELL-LINES

Mutation of the p53 gene is a common occurrence in human breast cancer s but is by no means universal. However, even in tumours where the gen e is not mutated altered levels of p53 protein are often detected. Thi s is also observed in cell lines derived from human breast cancers. By transfecting such cell lines containing either wild type or mutant p5 3 genes with a temperature-sensitive mutant mouse p53 gene we have est ablished that the cellular environment plays a critical role in the re gulation of p53 protein expression. The results suggest that tumours t hat aberrantly express wild-type p53 may have lost the normal growth r egulatory response to the protein and thus be functionally similar to those expressing the mutant protein.