Identification of matrix metalloproteinase-9 as an independent prognostic marker in laryngeal and hypopharyngeal cancer with opposite correlations to adhesion/growth-regulatory galectins-1 and -7 SVEN SAUSSEZ1,2, STÈPHANIE CLUDTS1, AURELIE CAPOUILLEZ1, GEOFFREY MORTUAIRE3,

The enzymatic activity of matrix metalloproteinase-9 (MMP-9) suggests that its presence in hypopharyngeal and laryngeal squamous cell carcinomas (HSCCs, LSCCs) could have prognostic value. We tested this hypothesis by quantitative morphometric analysis of immunohistochemical staining in histological sections of 73 stage IV HSCCs and 45 LSCCs (30 cases of stage I/II, 15 cases of stage IV). As compared to tumour-free epithelium an increase for the labelling index in LSCCs reached statistical significance (p=0.04). Specimens of Reinke's edema were strongly higher in this parameter compared to tumour-free tissue area (p=0.000001), underscoring an association between the level of MMP-9 expression and inflammation. Focusing on patients' recurrence status we identified thresholds for the labelling index of 10% for HSCCs and 18% for LSCCs, both indicating rapid recurrence and dismal prognosis unless surpassed. When relating data for MMP-9 to those for three adhesion/growth-regulatory galectins, a positive correlation with galectin-7 expression was detected in LSCCs. This finding suggests a possible potential role of this endogenous lectin as inducer of MMP-9 gene expression in situ. Of note, galectin-1 expression was negatively correlated with MMP-9 and that of galectin-3, a substrate of MMP-9, not related. In conclusion our study delineated a prognostic role of MMP-9 immunodetection in high-stage HSCCs and in LSCCs when separating patients by a distinct threshold for the labelling index. Moreover, it indicated associations between MMP-9 and multifunctional galectins-1 and -7 in situ.