Abstract: Objective　To detect the expression of silent information regulator 1（SIRT1）in the clinical prostate cancer tissues and cells, and to explore the role of SIRT1 in the development of prostate cancer. Methods A total of 8 human prostate adenocarcinoma tissues and adjacent normal prostate tissues were acquired from the First Affiliated Hospital of Liaoning Medical University and the SIRT1 and P53 mRNA and protein expression levels in prostate tissues were determined by Real-time PCR and Western blot. The normal human prostate epithelial cells PrEC and human prostate carcinoma cell lines LNcap, PC3and DU145 were cultured in vitro, then the SIRT1 and P53 mRNA expression levels were detected by real-time PCR. The whole cell protein lysates, nuclear and cytosolic protein lysates were prepared for Western blot to determine the SIRT1 and P53 protein expression levels in PC3 and DU145 cells. Results SIRT1 was found to be overexpressed in human prostate cancer tissues compared with adjacent normal prostate tissue（P<0.01）. SIRT1 was significantly overexpressed in human prostate cancer cells LNcap, PC3 and DU145 compared with PrEC cells at mRNA and protein levels （P<0.01）and SIRT1 was predominantly localized in the nuclear of PC3 and DU145 cells（P<0.01）. Conclusion Nuclear SIRT1, via P53 dependent and independent activation, could contribute to the development of prostate cancer, and pay a foundation for exploring the possible role and underlying mechanisms of SIRT1 on the malignant behavior of prostate cancer.

Key words: silent information regulator 1（SIRT1）, prostate cancer, p53, PC3, DU145