Altered expression of secreted mediator genes that mediate aggressive breast cancer metastasis to distant organs

Abstract

Due to the heterogeneous nature of breast cancer, metastasis organotropism has been poorly understood. This study assessed the specific cancer‐related gene expression changes occur-ring with metastatic breast cancer recurrence to distant organs compared with non‐metastatic breast cancer. We found that several secreted mediators encoding genes notably, LCN2 and S100A8 overexpressed at the distant metastatic site spine (LCN2, 5‐fold; S100A8, 6‐fold) and bone (LCN2, 5‐fold; S100A8, 3‐fold) vs. primary tumors in the syngeneic implantation/tumor‐resection metastasis mouse model. In contrast, the ESM‐1 encoding gene is overexpressed in the primary tumors and markedly downregulated at distant metastatic sites. Further digging into TCAGA‐BRCA, SCAN‐B, and METABRIC cohorts data analysis revealed that LCN2, S100A8, and ESM‐1 mediators encoding individual gene expression scores were strongly associated with dis-ease‐specific survival (DSS) in the METABRIC cohort (hazard ratio (HR) > 1, p < 0.0004). The gene expression scores predicted worse clinically aggressive tumors, such as high Nottingham histo-logical grade and advanced cancer staging. Higher gene expression score of ESM‐1 gene was strongly associated with worse overall survival (OS) in the triple‐negative breast cancer (TNBC) and hormonal receptor (HR)‐positive/HER2‐negative subtype in METABRIC cohort, HER2+ sub-type in TCGA‐BRCA and SCAN‐B breast cancer cohorts. Our data suggested that mediators encoding genes with prognostic and predictive values may be clinically useful for breast cancer spine, bone, and lung metastasis, particularly in more aggressive subtypes such as TNBC and HER2+ breast cancer.