Anterior gradient protein 2 (AGR2) is an independent prognostic factor in ovarian high-grade serous carcinoma

Abstract

Ovarian high-grade serous carcinoma (HGSC, type 2 ovarian carcinoma) is a poor prognosis cancer with limited therapeutic options. We aimed to investigate the expression pattern and prognostic potential of the metastasis-promoting protein anterior gradient 2 (AGR2) in primary HGSC. Immunohistochemistry was applied to a cohort of 124 primary HGSCs using tissue microarrays. Additionally, in 48 type 1 carcinomas (low-grade serous (LGSC), endometrioid (EC), clear cell (CCC), and mucinous carcinoma (MC)), AGR2 expression was investigated in an exploratory approach. A strong expression of AGR2 was seen in 15 HGSCs (12.1 %) and was significantly linked to shortened overall survival (OS, p = 0.011) and also for progression-free survival (PFS, p = 0.001) in the setting of adjuvant platinum-based chemotherapy (CTX). Multivariate survival analysis including age, stage, and residual tumor after surgery revealed that AGR2 expression was an independent prognostic marker for OS (p = 0.001) and PFS (p = 0.001) in HGSC. In type 1 carcinomas, AGR2 was significantly increased as compared to HGSC (p = 0.001) and was seen in subsets of all histological types, low-grade serous LGSC, EC, CCC, and MC. In particular, strong diffuse staining was seen in LGSC and MC. There was no association between AGR2 and estrogen receptor expression in ovarian type 1 or type 2 carcinomas. AGR2 expression identifies highly aggressive HGSC with a compromised prognosis for which novel therapeutic options are needed. Our data strongly support the further evaluation of AGR2 as a therapeutic target and a potential marker for response to platinum-based CTX in this tumor entity.