Expression of hypoxia-inducible factor 1alpha in human normal, benign, and malignant prostate tissue. OBJECTIVE: To investigate hypoxia-inducible factor 1alpha (HIF-1alpha) protein expression in normal prostates (NP), benign prostatic glandular hyperplasia (BPH), and prostate adenocarcinoma (Pca). METHODS: HIF-1alpha protein expression was determined by immunohistochemistry in formalin-fixed and paraffin-embedded specimens obtained from 13 cases of NP, 28 cases of BPH, and 34 cases of Pca. In cases of Pca, the relationship between HIF-1alpha protein expression and certain clinicopathological factors, such as clinicopathologic stage and Gleason score, was evaluated. RESULTS: NP manifested no immunoreactivity, whereas Pca and BPH showed significantly increased HIF-1alpha protein expression. A significantly higher expression was observed in Pca specimens compared with BPH samples. In Pca, no significant relationship between HIF-1alpha protein expression and clinicopathological factors was found. CONCLUSION: Our findings of increased HIF-1alpha protein expression in BPH and Pca specimens suggests the potential role of this protein in BPH and Pca.