Period 1 (<i>PER1</i>): A novel glucocorticoid-responsive gene involved in cortisol-induced proliferation of androgen-independent human prostate cancer DU145 cells.

Glucocorticoid receptor (GR) has been implicated in prostate carcinoma and possibly involved in cancer growth and progression. Therefore, in this study, we examined whether the genes involved in cell proliferation regulation were induced by cortisol in androgen-independent human prostate cancer DU145 cells. Gene expression profiling of the DU145 cell pathway was conducted using the RT² Profile PCR Array System, quantitative reverse transcriptase polymerase chain reaction, and immunoblot analysis. These analyses demonstrated that the expression level of Period 1 (<i>PER1</i>), a gene associated with an organism's biological clock and involved in anti-apoptosis and cell growth, was markedly increased in DU145 cells treated with dexamethasone (DEX). In addition, analysis using short hairpin RNA demonstrated that products of PER1 were involved in the DEX-induced proliferation of DU145 cells. Therefore, <i>PER1</i> is considered a glucocorticoid-responsive gene that regulates DU145 cell proliferation induced by GR stimulation, thus potentially playing an important role in GR-related androgen-independent human prostate cancer.