Coexpression of aPKCλ/ι and IL-6 in prostate cancer tissue correlates with biochemical recurrence

Atypical protein kinase C lambda/iota (aPKC lambda/iota) and interleukin-6 (IL-6) have been implicated in prostate cancer progression, the mechanisms of which have been demonstrated both in vitro and in vivo. However, the clinical significance of the correlation between the expressions of these factors remains to be clarified. In the present study, we report a significant correlation between aPKC lambda/iota and IL-6 proteins in prostate cancer tissue by immunohistochemical staining. We evaluated the association of both proteins by analyzing clinicopathological parameters using chi-square test, Kaplan-Meier with log-rank test, and a Cox proportional hazard regression model in univariate and multivariate analyses. The results again showed that the expression of aPKC lambda/iota and IL-6 correlates in prostate cancer tissue (P < 0.001). Atypical protein kinase C lambda/iota was also found to correlate with the Gleason score (P < 0.001) and with biochemical recurrence after prostatectomy (P = 0.02). Furthermore, aPKC lambda/iota correlated with biochemical recurrence in a KaplanMeier and log-rank test (P = 0.01) and Cox analysis (P = 0.02 in the univariate analysis, P = 0.02 in the multivariate analysis). The coexpression of aPKC lambda/iota and IL-6 also correlated with biochemical recurrence by Kaplan-Meier and log-rank test (P = 0.005) and Cox analysis (P = 0.01 in the univariate analysis, P = 0.03 in the multivariate analysis). These results indicate a strong correlation between aPKC lambda/iota and IL-6 in prostate tumors, and that the aPKCk lambda/iota-IL-6 axis is a reliable prognostic factor for the biochemical recurrence of this cancer. (Cancer Sci 2011; 102: 1576-1581)