MSF expression was generally low or negligible in normal breast tissue derived from reduction mammoplasties (NB; n = 19). However, histologically normal breast from the resection margin of breast tumours (NB-T; n = 17) showed significantly higher expression than NB. Significant increases in MSF expression were also observed from NB to benign lesions (B; n = 8) and from any of these tissues (B, NB or NB-T) to malignant tumours (T; n = 23), whereas B and NB-T showed similar expression.
MSF was detected in approximately 85% of the tumours examined, being heterogeneously expressed in carcinoma cells as well as in fibroblasts and blood vessels. In a cohort of 71 tumours, high MSF expression was associated with larger tumour size and shorter patient overall survival. Stromal MSF produced the most significant results. Recombinant MSF stimulated the migration, but not the proliferation, of breast carcinoma cells, fibroblast and endothelial cells.