Prognostic values of Annexins and validation of the influence on cell proliferation, migration, and invasion in uveal melanoma.

Objectives: Uveal melanoma (UVM), the leading type of intraocular malignant tumor in adults, has an aggressive course with poor prognoses, high mortality, and lacking effective therapeutic targets and prognostic markers. Annexins are well known as dysregulated and correlated with aggressiveness and prognosis of various cancers. However, little is known about the expression pattern of Annexins in UVM and their prognostic value. This study aimed to investigate and verify the role of Annexins in the pathogenesis of metastatic UVM.

Methods: The mRNA expression of Annexins in UVM was analyzed from The Cancer Genome Atlas (TCGA) database and validated in three independent datasets (GSE22138, GSE27831, and GSE156877). The bioinformatics analysis and experimental verification of ANXA2 expression in UVM were performed to evaluate its influence on clinical prognosis, cell proliferation, migration, and invasion.

Results: Prognostic analysis suggested that high ANXA2/4 expression levels were significantly correlated with worse overall survival (OS), progress-free interval (PFI), and metastasis-free survival (MFS) prognoses. Meanwhile, the prognostic model (ANXA2/4) was built using the PFI-based LASSO analysis in TCGA-UVM and validated in GSE22138 and GSE27831. Multivariate Cox regression analyses indicated that the ANXA2/4 model is an independent prognostic factor associated with UVM. The expression analysis confirmed that ANXA2 was upregulated in metastatic patients. Then, ANXA2 mRNA was confirmed positive and expressed higher in four human UVM cell lines compared with ARPE19 cells, especially in two highly invasive metastatic types (C918 and MUM2B). Moreover, silencing ANXA2 blocked cell proliferation, migration, and invasion abilities of C918 and MUM2B while upregulating ANXA2 enhanced these cell functions remarkably in vitro, suggesting that ANXA2 had a positive effect on malignant biological properties of UVM cells. In addition, flow cytometry analysis showed that the knockdown of ANXA2 had a higher apoptotic rate than the control groups in C918 and MUM2B cells. ANXA2 overexpression had a lower apoptotic rate than those in the control group in OCM-1. In addition, ANXA2 expression had significant correlations with the tumor microenvironment and multiple tumor-infiltrating immune cells.

Conclusions: ANXA2 is a novel potential prognostic biomarker for the metastatic diagnosis of UVM.