Abstract

The degradation of the basement membrane by matrix-metalloproteinase(MMP) and serine protease is a critical point in tumor invasion and metastasis. We measured the activity of MMP-9 from 28 normal, 12 benign, and 126 breast cancer tissues using gelatin zymography with an image analysis system. Inactive MMP-9 was expressed in 17.5% of the cancer patients compared to 2.5% in 40 non-cancerous tissues(p=0.008). The active form of MMP-9(82kD) was expressed only in T2-T4 stages. During the early phase of breast cancer (DCIS and Tl stage) progression, only the production of inactive MMP-9 was increased. However, as the cancer grew or invaded skin(T2-T4), or with lymphovascular permeation, both production and activation of MMP-9 were increased. In conclusion, MMP-9 productian was the main cause of increased MMP-9 activity during the ear1y phase, while both production and activation were increased in the late phase of breast cancer.

• Keywords: Breast cancer, Invasion, Zymography, MMP-9