Determination of matrix metalloproteinase 9 (MMP-9) protein expression in laryngeal squamous cell carcinomas based on digital image analysis.

Purpose: Matrix metalloproteinases (MMPs) is a superfamily of proteins involved in angiogenesis and metastatic tissue invasion in many cancers. Overexpression of MMP- 9 has been detected in significant proportions of laryngeal squamous cell carcinomas (LSCCs), but its prognostic impact remains unclear. In this study we performed a digital image analysis for analyzing MMP-9 protein expression in a series of LSCCs correlating them with clinicopathological factors.
Methods: MMP-9 protein expression level was determined immunohistochemically in 30 tissue sections surgically derived from patients (21 male and 9 female) with LSCC. Using digital image analysis, we measured their corresponding protein expression levels (staining intensity/S.I. range values 0-255).
Results: Moderate and high MMP-9 protein expression levels (grouping as 2+/3+ overexpression) were detected in 19/30 (63.3%) cases. Statistical significance was observed correlating stage with SI (p=0.02), whereas a borderline association with differentiation grade of the examined tumors was also registered (p=0.05). Interestingly, high levels of MMP-9 expression were observed in cases that demonstrated a significant level of inflammatory (predominantly lymphocytic) infiltration.
Conclusion: MMP-9 protein overactivation is a frequent and significant genetic event in LSCC, correlating with its biological behavior (increased TNM stage). MMP-9 seems to mediate an epithelial-stromal intra-reaction correlating also with induction of specific inflammation pathways.