Objective To investigate the expression of programmed cell death 5（PDCD5） in tissues of normal human prostate（NP）

benign prostatic hyperplasia（BPH）

and prostate cancer（PCa） in order to assess the clinical role of PDCD5 in PCa.Methods PDCD5 expression was determined by EnVision immunohistochemical staining in formalin-fixed and paraffin-embedded specimens obtained from 12 subjects with NP

22 with BPH

and 22 with PCa.In addition

PCa cases were classified as low/middle-risk（Gleason sum≤7） and high-risk（Gleason sum>7） on the basis of Gleason grade.Positive expression rates and intensity of PDCD5 protein were observed under light microscope and analyzed with computer imaging technique.Expression of PDCD5 was compared among different prostatic tissues.Results The expression of PDCD5 was significantly lower in tissue of PCa than in tissues of NP and BPH（P<0.01）.However

there was no significant difference in PDCD5 expression between tissues of NP and BPH.In addition

the expression of PDCD5 was further downregulated with the increase of Gleason sum in PCa.Conclusions By downregulating apoptosis

low PDCD5 expression may play an important role in the occurrence and development of PCa.PDCD5 is supposed to have a potential clinical value to be a new predictor of progression and target of gene therapy in PCa.