CSN6 expression is associated with pancreatic cancer progression and predicts poor prognosis.

Constitutive photomorphogenesis 9 (COP9) signalosome 6 (CSN6) plays an essential role in tumor development. The present study aims to demonstrate that CSN6 is an important biomarker and has prognostic value for patients with pancreatic ductal adenocarcinoma (PDAC). We analyzed CSN6 expression levels in PDAC and adjacent non-cancerous tissues using immunohistochemistry (IHC) and quantitative real-time PCR (qPCR) analysis. We found that CSN6 was highly expressed in PDAC tissues, contrasting to adjacent non-cancerous tissues. Interestingly, CSN6 expression was positively associated with proliferating cell nuclear antigen (PCNA) expression. Further investigation indicated that CSN6 knockdown significantly suppressed the proliferation of PDAC cells and decreased the expression levels of PCNA, while CSN6 overexpression increased the proliferation, as well as the expression levels of PCNA in PDAC cells. Furthermore, a χ2 test indicated that the expression of CSN6 in PDAC tissues was markedly associated with tumor infiltration and serum carbohydrate antigen 19-9 levels. In addition, univariate and multivariate analyses showed that CSN6 levels were significantly correlated with poor clinical outcomes of patients with PDAC. Kaplan-Meier analysis showed that patients with high expression of CSN6 had shorter overall survival. These results suggest that the expression of CSN6 correlates with the progression of PDAC, resulting in poor prognosis. Thus, CSN6 may play a significant role in the development of PDAC and is a potential target to prevent and treat PDAC.