Purpose: Matrix metalloproteinases (MMPs) are known to play an important role in extracellular matrix remodeling during the process of tumor invasion and metastasis. However, little is known about their role in preinvasive lesions and early esophageal carcinomas.
Method: Immunohistochemical analysis of matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9) expression was carried out in paraffin-embedded sections of surgically resected esophageal squamous cell carcinoma (ESCC) (58 cases) and paired distal normal esophageal tissues (44 cases) and correlated with clinicopathological parameters.
Result: Overexpression of MMP-2 and MMP-9 proteins was observed in 39 (67%) and 32 (55%) of the 58 ESCCs, respectively localized in tumor cell cytoplasm and stromal elements. Histological evaluation of hematoxylin- and eosin-stained 44 matched distal normal esophageal tissue sections revealed that 26 comprised of normal epithelium, while 15 tissues showed evidence of dysplasia and three tissues showed hyperplasia. Interestingly, 12 (80%) and 13 (87%) of these 15 dysplasias showed immunostaining for MMP-2 and MMP-9 proteins, respectively. Low levels of MMP-2 and MMP-9 were observed in 10 (38%) and 6 (23%) of 26 matched histologically normal esophageal tissues, respectively. Higher MMP-2 immunopositivity was observed in well and moderately differentiated SCCs in comparison with poorly differentiated tumors. The expression of MMP-2 was significantly reduced with the progressive de-differentiation of esophageal SCCs ( P =0.03). Overexpression of MMP-2 and MMP-9 in dysplasia as well as SCC suggests that these alterations occur in early stages of esophageal tumorigenesis.
Conclusion: Increased levels of MMP-2 and MMP-9 proteins in ESCCs as compared to normal esophageal tissues suggest their association with esophageal tumorigenesis. Increased levels of these MMPs are observed in majority of dysplasias analyzed herein, indicating that these alterations may be early events in esophageal tumorigenesis. In-depth studies are warranted to determine their role in development and progression of esophageal cancer.