Patient-Derived Procoagulant Breast Fibroblasts Expressing Tissue Factor Promote Breast Cancer Cell Migration.

[UNLABELLED] Cancer-associated fibroblasts (CAFs) play a key role in breast cancer progression and exhibit a procoagulant phenotype within the tumour microenvironment (TME). We hypothesised that this procoagulant phenotype correlates with a CAF-like phenotype and that fibroblasts distant from the immediate TME are less procoagulant. We also proposed that the procoagulant phenotype contributes functionally to breast cancer progression. Primary fibroblasts were cultured from human breast tumour tissue and matched normal breast tissue from regions distant to the tumour. Conditioned media (CM) from these cells were collected for analysis. We conducted immunocytochemistry, western blotting, transforming growth factor beta 1 (TGFβ1) ELISA, tissue factor (TF) activity and procoagulant activity assays. A positive correlation was found between the expression of TF and alpha-smooth muscle actin (α-SMA), a CAF marker, and between fibroblast procoagulant activity and secretion of the CAF inducer, TGFβ1. Interestingly, fibroblasts from distant breast tissue exhibited CAF-like and procoagulant phenotypes similar to tumour-associated fibroblasts. To assess functional relevance, scratch wound migration assays were performed using MCF-7 breast cancer cells. Inhibition of TF derived from both tumour and distant fibroblasts significantly reduced MCF-7 cell migration. Combined inhibition of TF and TGFβ1 in distant fibroblast CM further suppressed migration. These findings suggest that tumour-derived influences may extend beyond the immediate TME, inducing a CAF-like, procoagulant phenotype in fibroblasts from histologically normal breast tissue. Furthermore, fibroblast-derived TF promotes breast cancer cell migration which is important for the processes of invasion and metastasis. This further highlights TF as a promising therapeutic target in breast cancer.

[GRAPHICAL ABSTRACT] [Figure: see text]

[SUPPLEMENTARY INFORMATION] The online version contains supplementary material available at 10.1007/s10911-026-09596-w.