Mast Cells in 10-Dimethyl-1,2 Benzanthracene (DMBA)-Induced Rat Mammary Carcinomas: Relationship with Matrix Metallproteinase (MMP)-2 and MMP-9 Expression

ABSTRACT

BACKGROUND: It has been suggested that mast cells are involved in the tumor growth and progression by production of a variety of enzymes and growth factors. They were studied in the 10-dimethyl-1,2 benzanthracene (DMBA)-induced rat mammary tumors, and evaluated in relation with the production of tryptase, chymase, and matrix metalloproteinase (MMP)-2 and MMP-9. METHODS: Preneoplastic and neoplastic breast tissues of Sprague-Dawley female rats were obtained every week after DMBA treatment for 12 weeks. Toluidine blue stain was used for the identification of mast cells. Mast cell tryptase was studied by immunohistochemistry, and chymase by esterase stain. MMP-2 and MMP-9 were measured by Western blotting. RESULTS: The numbers of mast cells in breast cancers were higher than in preneoplastic tissues, and there was a positive correlation between the numbers of tryptase-positive cells and the tumor size. MMP-9 quantity was correlated with the numbers of toluidine blue and chymase positive cells, but not with tryptase-positive cells and tumor size. Both active and inactive forms of MMP-2 and MMP-9 were identified in zymogram. CONCLUSIONS: The mast cells are increased in the DMBA-induced breast cancers, and their tryptase and chymase may play a role in tumor progression with or without participation of MMP-2 and MMP-9.