Predictive and Prognostic Value of SUOX Expression in Pancreatic Ductal Adenocarcinoma

Background/Aim: Sulphite oxidase (SUOX) is a metalloenzyme that catalyses ATP synthesis via oxidative phosphorylation in the mitochondria. Although SUOX has been reported to affect the invasiveness and differentiation of cancer cells, its clinicopathological significance in pancreatic adenocarcinoma (PDAC) remains unclear. In this study, we investigated the utility of SUOX expression as a prognostic factor in PDAC. Patients and Methods: This study included 56 patients with PDAC who underwent pancreatic resection at the Kurume University Hospital between 2014 and 2018. SUOX immunohistochemistry was evaluated using tissue microarray specimens from patients. Patients were classified into a high SUOX expression group (≥10% of cells stained) or a low SUOX expression group (<10% of cells stained), and the associations of SUOX with clinicopathological characteristics and survival were analysed. Statistical analysis was performed using Cox regression analysis, the Kaplan–Meier method, and log-rank test. Results: SUOX was expressed in the cytoplasm of normal pancreatic ductal epithelium, pancreatic acinar cells, and islets of Langerhans. Although we did not find any significant correlation between SUOX expression and clinicopathological factors, SUOX was identified as an independent prognostic factor based on univariate and multivariate analyses. Pathological stage was also an independent prognostic factor. The high SUOX expression group showed a significantly poorer prognosis than the low SUOX expression group (p=0.018). Conclusion: SUOX-mediated mitochondrial metabolism in PDAC may be a factor influencing prognosis and SUOX may be a potential novel prognostic biomarker.