Expression of matrix metalloproteinases (MMP-2 and MMP-9) in recurrent respiratory papillomas and laryngeal carcinoma: clinical and morphological parallels

The task of the present study was to investigate the expression of MMP-2 and MMP-9 in recurrent respiratory papillomas (RRP) and accomplish a comparative analysis with those in laryngeal squamous cell carcinoma (LSCC). The immunohistochemical expression of MMP-2 and MMP-9 was investigated in specimens taken from RRP (n = 38) and LSCC (n = 39) patient groups, and the normal tissue of vocal fold (n = 12, control group). The expression of MMP-2 and MMP-9, both in epithelium and stroma cells, was graded on a semiquantitative scale, ranging from 0 (no expression) to 18 points (high expression). Statistically significant differences in the expression of MMP-2 and MMP-9, both in epithelium and stroma among the RRP, LSCC patients and control group (epithelium) with the LSCC group having the highest MMPs expression scores were revealed. However, no statistically significant correlations among expression of MMPs and clinical and/or morphological features were found in the group of RRP patients. The MMP-2 stroma value of 10.4 points was determined as the optimum point (limiting value) for separating RRP and LSCC patient groups. Results of the present study indicate that the expression of both MMP-2 and MMP-9 are up-regulated early in development of laryngeal papillomas, when the benign neoplastic lesion begins and the next determinant step is concerned with the occurrence of malignization. These results seem promising, as they may improve our understanding of the molecular events leading to the papilloma formation and development, however, further research is needed.