Migration-stimulating factor as a novel biomarker in salivary gland tumours

The identification of novel stratification biomarkers would benefit the clinical management of patients with salivary gland tumours. Migration-stimulating factor (MSF) is a potent stimulator of cell invasion, matrix remodelling and angiogenesis. The aim of this study was to determine whether MSF was expressed in salivary gland tumours and its potential value as a diagnostic biomarker.

Paraffin-embedded archival specimens of small salivary gland tumours were stained with an MSF-specific antibody. The specimens included 27 malignant and seven benign tumours; histologically normal salivary gland adjacent to the tumour was present in 16 specimens. MSF expression was assessed by consensus of 2-4 independent observers according to various indices, including 'overall MSF grade', 'percentage of area stained' and 'intensity of the staining'. The motogenic effect of MSF on a salivary gland tumour cell line, HSG, was examined in the transmembrane assay.

Overall MSF expression increased significantly in a step-wise fashion from normal salivary gland to benign and malignant tumours (P = 0.04-0.0001); with moderate/strong positive specimens representing 6%, 33% and 74% of the normal, benign and malignant specimens, respectively. MSF was heterogeneously expressed in both carcinoma and stromal cell compartments, its expression being higher in malignant than benign tumours regarding various MSF indices. In tissue culture studies, exogenous MSF stimulated the migration of HSG cells.

These immunohistochemical and functional studies suggest that MSF expression is a potentially useful biomarker of salivary gland tumour progression.