p53 functional activation is independent of its genotype in five esophageal squamous cell carcinoma cell lines

p53 mutations have been found in many esophageal squamous cell carcinoma (ESCC) clinical specimens and cell lines. We reasoned that functional inactivation of wild-type p53 or the functional activation of mutant-type p53 might exist in these specimens and cell lines. In this study, we identified the correlation between p53 functional activation and its genotype in five different ESCC cell lines. To examine the potential p53 activation in a certain ESCC cell line, DNA damage methods including X-ray exposure and cisplatin treatment were employed to treat cells. Further, the expression of p53 protein and four transcripts of well-known p53 target genes were investigated using Western blot and reverse transcriptionpolymerase chain reaction (RT-PCR) after cell exposure to DNA damage. The results showed that in KYSE 30 cell line with mutant p53 and KYSE 150 with wild-type p53, p53 could be activated by DNA damages. However, p53 could not be activated following the DNA damages in YES 2 with wild-type p53, KYSE 70 with mutant p53, and EC9706 with unknown p53 genotype. All our data indicated that p53 function in certain cells is not closely correlated with its genotype. To judge p53 function in a particular cell line, it is important to examine the p53 functional activation, but not to simply rely on the p53 genotype.