The prognostic value of anterior gradient-2 (AGR2) in tumours remains inconclusive. Here, we systematically reviewed the literature evidence and assessed the association between AGR2 expression and prognosis in solid tumours. The primary outcomes were overall survival (OS), disease-specific survival (DSS), and disease-free survival (DFS)/recurrence-free survival (RFS)/progression-free survival (PFS). All analyses were performed by STATA 12.0, with the hazard ratio (HR) or odds ratios (OR), and 95% confidence interval (CI) as the effect size estimate. A total of 20 studies containing 3285 cases were included. Pooled analyses revealed that AGR2 overexpression had an unfavourable impact on OS (HR 1.93, 95% CI 1.32–2.81) and time to tumour progression (TTP) (DFS/RFS/PFS) (HR 1.60 95% CI 1.06–2.40) in solid tumour patients. Subgroup analyses indicated that AGR2 overexpression in breast cancer patients was significantly associated with poor OS (HR 3.02, 95% CI 1.03–8.81) and TTP (HR 1.93, 95% CI 1.17–3.20). Excluding breast cancer, AGR2 overexpression was also found to have a significant correlation with poor OS in the remaining solid tumour patients (HR 1.51, 95% CI 1.04–2.19). Overall, AGR2 might be a potential biomarker to predict prognosis in solid tumour patients.

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ObjectiveReciprocal cellular crosstalk within the tumour microenvironment (TME) actively participates in tumour progression. The anterior gradient-2 (AGR2) can be secreted to extracellular compartments and contribute to colorectal cancer (CRC) metastasis. We investigated the cellular source for secreted AGR2 in the TME and underlying mechanisms mediating secreted AGR2’s effects.DesignTissue microarray, tumour tissues, blood samples and tumour-associated neutrophils (TANs) from patients with CRC were isolated for phenotypical and functional analyses. The role of TAN-secreted AGR2 was determined in neutrophil-specific Agr2 knockout (Agr2f/f;Mrp-Cre) mice. The biological roles and mechanisms of secreted AGR2 in CRC metastasis were determined in vitro and in vivo.ResultsTANs were a predominant cell type for secreting AGR2 in the TME of CRC. TANs-secreted AGR2 promoted CRC cells’ migration. Neutrophils-specific ablation of Agr2 in mice ameliorated CRC liver metastases. The heavy chain of CD98 (CD98hc) served as the functional receptor for secreted AGR2. Mechanistically, secreted AGR2 increased xCT activity in a CD98hc-dependent manner, subsequently activating Ras homologue family member A/Rho-associated protein kinase 2 cascade. CRC cells actively recruited TANs through the C-X-C motif chemokine 2. Moreover, CRC-derived transforming growth factor beta 1 (TGF-β1) educated peripheral blood neutrophils to become AGR2+ TANs that secrete AGR2. Abundant infiltration of AGR2+ TANs and high expression of TGF-β1 and CD98hc–xCT were correlated with poor prognosis of patients with CRC.ConclusionsOur study unveils a novel crosstalk between TANs and CRC cells involving the secreted AGR2–CD98hc–xCT axis that promotes metastasis and impacts the outcomes of patients with CRC.