Fig 1. Association between RRM1 expression and prognosis in pancreatic cancer.

(A) Left panel: representative immunohistochemical staining of pancreatic ductal adenocarcinomas with positive RRM1 expression. Right upper panel: adjacent normal pancreatic tissue. Right lower panel: ductal adenocarcinoma. (B) Representative immunohistochemical staining of low and high RRM1 expression levels. For the immunohistochemical staining of RRM1 in pancreatic cancer, the islets of Langerhans served as a positive internal control to evaluate the expression. RRM1 expression level was graded as low (no staining or weak intensity staining comparing to internal control in less than 30% of cells) or high (strong intensity staining in more than 30% of cells based on cytoplasmic staining intensity). The staining grade of RRM1 expression was assessed by two investigators and reviewed by one pathologist. (C) Immunohistochemical staining of non-malignant pancreatic disease tissues. Left panel, intraductal papillary mucinous neoplasm (IPMN); middle panel, serous cyst neoplasm (SCN); right panel, mucinous cyst neoplasm (MCN). (D), (E) Kaplan-Meier curves for overall survival (D) and disease-free survival (E) of patients with pancreatic cancer with high or low RRM1 expression. RRM1 immunoreactivity in tumor cells was significantly associated with a worse prognosis (overall survival, P = 0.006, log-rank test; disease-free survival, P = 0.0491, Gehan-Breslow-Wilcoxon test).