Collagenolytic Activity in Malignant Melanoma: Physicochemical Studies¹ Free

Human malignant melanoma was shown to contain collagenolytic enzymes. With the use of radioactively labeled reconstituted collagen substrate, the enzyme activity of the tumor homogenate supernatant released radioactivity up to 24 times greater than normal skin and 100% more than benign melanotic tumors such as a junctional nevus and a cellular blue nevus. The known specific collagenase inhibitors significantly inhibited the enzyme activity, whereas soybean trypsin inhibitor did not. Kinetic studies demonstrated a linear increase of collagenolytic activity with respect to enzyme concentration and time of incubation. The optimum pH for enzyme action was 8.5. Disc electrophoresis of the reaction mixture showed collagen degradation products such as β^A, α^A, and α^B. Viscometric studies demonstrated that melanoma crude enzyme decreased the specific viscosity of salt-soluble guinea pig tropocollagen. The denaturation temperature of tropocollagen was decreased as a result of incubation with the melanoma homogenate. These results clearly indicate that the tumor contained active collagenase in vivo.