Increased Akt and phosphorylated Akt expression are associated with malignant biological features of prostate cancer in Japanese men

To investigate the relationship between the expression of Akt (a serine/threonine kinase that plays a central role in tumorigenesis), phosphorylated Akt (p-Akt), prostate cancer tumour grade, androgen receptor (AR)-staining score, and Ki67 labelling index (LI) in Japanese men. The expression and activation of the cell survival protein Akt was analysed by immunohistochemical staining of paraffin-embedded tissue microarray sections of prostate carcinoma taken from 52 Japanese men who under radical prostatectomy. The correlation between the expression of Akt and p-Akt, and their relationship to primary Gleason grade, AR expression and Ki-67 LI was investigated. The expression of Akt and p-Akt were positively related to primary Gleason grade (Fisher's exact test, P = 0.002 and P = 0.032, respectively). Both AR-staining score and Ki67 LI were were positively related to the expression of Akt (both P < 0.001) and p-Akt (P < 0.001 and P = 0.008, respectively). There was a significant positive correlation between the expression of Akt and p-Akt (Spearman's correlation, r = 0.644, P < 0.001). Increased expression of both Akt and p-Akt were associated with higher tumour grade as well as a higher AR-staining score and Ki67 LI. These data indicate that Akt and p-Akt might be molecular markers for detecting malignant biological features of prostate cancer in the Japanese population.