Association Between Matrix Metalloproteinase-9 (MMP-9) Immunohistochemical Expression and Clinicopathological Features in Equine Melanoma.

Authors

J Pimenta, D Moreira, J Prada, L Monteiro, F Garcez, L Delgado, M Cotovio

Published in

Journal of equine veterinary science. Pages 106158. Sep 27, 2026. Epub Sep 27, 2026.

Abstract

Equine melanoma is one of the most important oncological diseases in horses and exhibits a distinct biological behavior compared with melanoma in other species. Matrix metalloproteinase-9 (MMP-9) has been associated with tumor aggressiveness and metastasis in human and canine melanoma, but its expression in equine melanoma remains unknown.
Evaluate the immunohistochemical expression of MMP-9 in equine melanomas and investigate its association with clinicopathological features.
68 formalin-fixed, paraffin-embedded equine melanomas from 48 gray horses were evaluated immunohistochemically for MMP-9 expression. Associations between MMP-9 expression and clinicopathological variables were assessed, including histological classification, tumor size, excision interval, ulceration, circumscription, tumor localization, and stromal immunolabeling. Statistical significance was considered when p < 0.05.
Overall, 69.1% of melanomas exhibited low MMP-9 expression, 27.9% high expression, and 2.9% were negative. Malignant melanomas exhibited significantly higher MMP-9 expression than benign tumors (p = 0.04). Medium-sized tumors showed significantly higher MMP-9 expression than small tumors (p = 0.02). MMP-9 immunolabeling was positively correlated with excision interval (p = 0.03), and longer excision intervals were associated with histological malignancy (p < 0.001). No significant associations were identified between MMP-9 expression and ulceration, tumor circumscription, horse age, tumor localization, or number of tumors.
This study provides the first immunohistochemical characterization of MMP-9 expression in equine melanoma. MMP-9 expression was predominantly low, but was significantly associated with histological malignancy, medium tumor size, and longer excision intervals. These findings may help to expand the current clinicopathological characterization of equine melanoma.

PMID:
42801954
Bibliographic data and abstract were imported from PubMed on 28 Sep 2026.

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