p53-dependent induction of heat shock protein 27 (HSP27) expression

Transcriptional activation of the p53 target genes plays a critical role in the cellular response to DNA damage, hypoxia, cellular stress and other signals regulating the cell cycle and apoptosis. The discovery of new p53 target genes continues to reveal novel mechanisms of action of this multifaceted protein. We used cDNA arrays to search for p53-regulated genes in prostate cancer cells. In this report, we describe robust induction of heat shock protein 27 (hsp27) in prostate cancer cells (DU145, LNCaP, PC3) following wild-type p53 expression from an adenoviral p53 expression vector (AdWTp53). A mutant p53 (R175H)-containing adenoviral expression vector did not induce hsp27. hsp27 expression was not altered in prostate cancer cells following expression of cyclin-dependent kinase inhibitors: p21(waf1/cip1) and p27(kip1) from adenoviral expression vectors. Treatment of cells with staurosporine, an apoptosis-inducing agent, did no affect hsp27 expression. These observations provide evidence that induction of hsp27 expression was wild-type p53-specific and was not due to non-specific effects of cell growth arrest and/or apoptosis. Previous studies and the experiment reported here show induction of hsp27 expression in response to androgen ablation, a physiological state that induces apoptosis in prostatic epithelial cells. The nature of p53 and hsp27 interactions in the regulation of apoptosis and/or cell growth needs to be further defined.