AGR2 expression in ovarian tumours: a potential biomarker for endometrioid and mucinous differentiation

Aims: To examine AGR2 expression in ovarian epithelial tumours and its potential role as a prognostic biomarker. Methods: Tissue microarray technology and immunohistochemistry were used to investigate AGR2 expression in ovarian epithelial tumours and in non-neoplastic ovarian epithelium. For the carcinomas, the expression data were correlated with clinicopathological features and disease outcome. Results: AGR2 was expressed in all benign, borderline and malignant mucinous tumours and in a high proportion of endometrioid carcinomas (89%). AGR2 was frequently expressed in benign and borderline serous tumours (76% and 95%, respectively), but less commonly expressed in serous carcinomas (19%, p < 0.001). AGR2 expression in ovarian carcinomas was inversely correlated with p53 and p16 expression (p = 0.002 and p < 0.001, respectively), and independent of CA125 expression. AGR2 expression was more common in carcinomas which presented with early-stage compared with late-stage disease (p = 0.009) and AGR2 was expressed in carcinomas with better outcome (22% relapse rate of AGR2 positive cancers compared with 74% relapse rate for AGR2 negative cancers, p = 0.001). Conclusion: Our findings indicate that AGR2 expression is associated with mucinous carcinomas and their precursor lesions and endometrioid cancers. Additionally, AGR2 may be an important prognostic biomarker of ovarian cancer.