Accumulation of cell cycle regulatory proteins, p21 and p27, induced afterhyperthermia in human glioma cells

It was investigated whether there was a relationship between p53-p21 and p2 7 induction pathways in the cellular response of glioma cells to hypertherm ia. Two glioma cell lines were employed. A-172 cells had the wild-type of p 53, and U251 cells had the mutant-type of p53. An adenovirus harbouring wil d-type p53 was also used for the overexpression. The protein induction by h yperthermia was monitored by Western blot analysis. In U251 cells, the expr ession of wild-type p53 and hyperthermia had an additional cytotoxic effect , but did not affect A-172 cells. Significant p21 accumulation by hyperther mia was recognized in A-172 cells, and was also recognized in p53-transduce d U251 cells. On the other hand, the accumulation of p27 by hyperthermia wa s not seen in A-172 or U251 cells, and the exogenous expression of p53 did not affect the accumulation of p27 by hyperthermia in U251 cells. These fin dings suggest that the p53-p21 pathway is involved in the signal transducti on after hyperthermia, rather than the p27 pathway.