Extradomain-B Fibronectin is a molecular marker of invasive breast cancer cells

Breast tumor heterogeneity is a major impediment to oncotherapy. Tumor cells undergo rapid clonal evolution, thereby acquiring significant growth and invasive advantages. The absence of specific markers of these high-risk tumors precludes efficient therapeutic and diagnostic management of breast cancer. Given the critical function of tumor microenvironment in the oncogenic circuitry, we sought to determine the role of the extracellular matrix oncoprotein, extradomain-B fibronectin (EDB-FN), as a molecular marker of aggressive cancers. High-risk invasive cell lines generated from relatively less invasive MCF7 and MDA-MB-468 breast cancer cells by long-term TGF-{beta} treatment and chemoresistance demonstrated hybrid epithelial-mesenchymal phenotype, enhanced motility, and significantly elevated EDB-FN levels in 2D- and 3D-cultures. To determine if EDB-FN could serve as a therapy-predictive marker, the invasive cell lines were treated with MK2206-HCl, a pan-AKT inhibitor. Phospho-AKT depletion reduced EMT and invasion of the populations, with a concomitant decrease in EDB-FN expression, partly through the phosphoAKT-SRp55 pathway, demonstrating that EDB-FN expression is strongly associated with high-risk breast cancer. EDB-FN is a promising molecular marker for accurate detection, differential diagnosis, and non-invasive therapeutic surveillance of aggressive breast cancer.\n\nSummary StatementDynamic changes in invasive properties of breast cancer cells directly influence extradomain-B fibronectin levels, suggesting its potential role as a molecular marker for active surveillance and therapeutic monitoring of breast cancer.