p53-dependent induction of WAF1 by heat treatment in human glioblastoma cells.

Induction of WAF1 expression was investigated after heat treatment (44 degrees C, 30 min) in two human glioblastoma cell lines with the wild-type or a mutant p53 gene. WAF1 accumulation was induced by heat treatment in A-172 cells carrying the wild-type p53 gene but not in T98G cells carrying the mutant p53 gene. We examined whether this phenomenon was due to the induction of WAF1 expression. Northern blot analysis showed that heat treatment not only activated WAF1 but also up-regulated p53 expression only in A-172 cells carrying the wild-type p53 gene. Gel mobility shift assay indicated an increase in p53 DNA binding activity after heat treatment. These findings suggest that the WAF1 expression is heat-inducible in human glioblastoma cells and that this induction may be due to signal transduction mediated by p53 in response to heat stress.