Soluble N-terminal EphA2 fragment as a diagnostic biomarker and functional mediator of tumor progression in triple-negative breast cancer

Abstract

Triple-negative breast cancer (TNBC) lacks reliable biomarkers for early detection and remains a highly aggressive disease. Ephrin type-A receptor 2 (EphA2), a receptor tyrosine kinase frequently overexpressed in advanced cancers, undergoes MMP14-mediated cleavage that releases soluble N-terminal fragments. Here, we investigated the diagnostic and functional significance of this fragment in TNBC. Immunohistochemical analysis of clinical specimens revealed elevated EphA2 expression in TNBC tissues, with a trend toward higher levels in tumors of advanced stage and grade. To enable non-invasive detection, we established a dual-epitope sandwich ELISA targeting spatially distinct regions of the EphA2 extracellular domain. The assay showed concentration-dependent detection of recombinant EphA2 (EC₅₀, 48 ng/mL) and detected soluble EphA2 in TNBC cell-conditioned media. Serum analysis showed significantly higher EphA2 levels in TNBC patients compared with healthy controls (median 93.3 vs 25.6 ng/mL). In this exploratory cohort, ROC analysis yielded an AUC of 0.912 (95% CI, 0.862-0.962), with a sensitivity of 95.0% (95% CI, 86.3-98.6%) and a specificity of 78.3% (95% CI, 66.4-86.9%), and higher levels were associated with lymph node metastasis and higher histological grade. Functionally, recombinant EphA2-P328 promoted TNBC-cell migration and induced cell context-dependent changes in EMT-associated markers in vitro. Collectively, these findings support the soluble N-terminal EphA2 fragment as a candidate serum biomarker and an in vitro modulator of TNBC cell migration, warranting validation in larger independent cohorts and further mechanistic investigation.

The authors' abstract, as published at the source. Translational Oncology, 2026 · DOI ↗