MMP in Canine Mammary Gland Tumor

Mammary gland tumor (MGT) is one of the most common neopla- sias in female dogs, having ap- proximately 40~50% of them considered malignant (1) . Recently, matrix metalloproteinase (MMP) family is thought to be responsible for the accelerated breakdown of extra-cellular matrix (ECM) associated with tumor invasion and metastasis (2, 3) . Thus the aim of this study is to investigate the plasma MMP-2 and MMP-9 activity and MMP-2 and MMP-9 levels in canine MGT tissues. The activity of MMP-2 and MMP-9 of MGT tissues and nearby normal mammary gland tissues were evaluated by gelatin zymography. The results of this study indicated that the levels of MMP-2 and MMP-9 were significantly higher in tumor tissues than those in normal gland tissues. Plasma MMP-2 and MMP-9 levels in malignant cases were higher than those in benign as well as in non-tumor cases. The decreased plasma MMP-9 level was noted after surgery, but MMP-2 was not. Plasma MMP-9 levels were correlated with the level of MMP-9 in tumor tissues. This study indicated that the change of MMP-2 and MMP-9 levels are associated with tumor malignancy, and plasma MMP-9 activity may be used as a marker both in the follow-up and in the prognosis of canine MGT patients.