M. Okano1, E. Katsuta1, M. Oshi1, K. Takabe1 1Roswell Park Cancer Institute,Breast Surgery,Buffalo, NY, USA
Introduction: Annexin A1 (ANXA1) is a calcium-dependent phospholipid-linked protein, involved in anti-inflammatory effects, regulation of cellular differentiation, proliferation and apoptosis. Recently, we reported that ANXA1 is associated with triple-negative breast cancer (TNBC) and its poor prognosis. It was also reported that ANXA1 relates to epithelial mesenchymal transition (EMT). We hypothesized that ANXA1 expression associate with EMT that leads to poor prognosis of TNBC.
Methods: Clinical and RNA-seq data were all obtained from the Cancer Genome Atlas (TCGA). Patients were classified as either high or low expression of ANXA1 determined by automated scanning and selecting the threshold yielding the lowest p-value. Overall survival (OS) and Gene set enrichment analysis (GSEA) were conducted comparing high and low expression group. To validate the relationship between ANXA1 expression and survival, ANXA1 protein expression was assessed by Immunohistochemistry (IHC) in 48 TNBC patients. Patients were classified into either positive or negative based upon IHC score. Clinicopathological factors and survival were compared between them.
Results: TNBC patients had significantly higher levels of ANXA1 expression compare to non-TNBC patients in TCGA cohort (p<0.001). ANXA1 high and low expression group were 140 and 20 patients in TNBC, and 540 and 245 in non-TNBC in TCGA cohort, respectively. High expression of ANXA1 group showed significantly worse OS (5-year OS rate: 68.6% vs 100%, p=0.035) in TNBC patients. On the contrary, high expression of ANXA1 demonstrated better OS in non-TNBC patients (5-year OS rate: 88.4% vs 78.7%, p=0.004). This finding was validated in protein expression level by IHC. Among 48 cases of TNBC patients 17 cases (35.4%) were classified as ANXA1 positively group. OS was significantly shorter in patients with ANXA1 positive tumors compared with ANXA1 negative tumor (p=0.008). To explore the mechanism of worse survival of TNBC patients with ANXA1 high expression, GSEA was conducted between ANXA1 high and low expression group. GSEA demonstrated that high expression of ANXA1 group enriched not only EMT related genes (NES=1.916, p=0.004), but also IL2/STAT5 (NES=2.04, p<0.001) and TNF alpha signaling (NES=2.02, p<0.001) related genes as well.
Conclusion: High expression of ANXA1 in TNBC patients associated with worse OS. It may be able to be explained by its metastatic potential with up-regulated EMT signaling and aggressive characteristics with up-regulated TNF alpha and IL2/STAT5 signaling.