Sulfite oxidase (SUOX) is a metalloenzyme that plays a role in ATP synthesis via oxidative phosphorylation in mitochondria and has been reported to also be involved in the invasion and differentiation capacities of tumor cells. Here, we performed a clinicopathological investigation of SUOX expression in prostate cancer and discussed the usefulness of SUOX expression as a predictor of biochemical recurrence following surgical treatment in prostate cancer. This study was conducted using Tissue Micro Array specimens obtained from 97 patients who underwent radical prostatectomy at our hospital between 2007 and 2011. SUOX staining was used to evaluate cytoplasmic SUOX expression. In the high-expression group, the early biochemical recurrence was significantly more frequent than in the low-expression group (p = 0.0008). In multivariate analysis, high SUOX expression was found to serve as an independent prognostic factor of biochemical recurrence (hazard ratio = 2.33, 95% confidence interval = 1.32-4.15, p = 0.0037). In addition, Ki-67-labeling indices were significantly higher in the high-expression group than in the low-expression group (p = 0.0058). Therefore, SUOX expression may be a powerful prognostic biomarker for decision-making in postoperative follow-up after total prostatectomy and with regard to the need for relief treatment.
Keywords: Biochemical recurrence; Biomarker; Oxidative phosphorylation; Prostate cancer; SUOX.