Fig. 1

Immunohistochemical analysis of MMP14 expression in tumour nests and CAFs at the primary TSI.

Immunohistochemical staining of MMP14 of OSCC resected specimens in TSI. MMP14 expression in CAFs: negative, CAFs < 50% (a); positive, CAFs ≥ 50% (b). MMP14 expression at the tumour nest in the TSI (c−g). MMP14 score at the tumour nest: 0, none (c); 1, weak cytoplasmic expression without membrane expression (d); 2, moderate cytoplasmic expression or incomplete membrane expression (e); and 3, strong cytoplasmic expression or complete membrane expression (f). Assessment of MMP14 established ranges from 0 to 3+; sample scoring of 2 + to 3 + was ‘high’ and 0 to 1 + was ‘low’. Flowchart of the MMP14 co-scoring system (g). Total MMP14 expression in tumours and CAFs was examined as follows: high-risk (cases that were CAFs-positive and whose tumour scores were high) and low-risk (cases that were not high-risk). Original magnification: a−f, 400× HPF. CAFs, cancer-associated fibroblast; TSI, tumour–stromal interface