Purification and Characterization of Extracellular Matrix-degrading Metalloproteinase, Matrin (Pump-1), Secreted from Human Rectal Carcinoma Cell Line1

A metalloproteinase with M, 29,000 was purified to homogeneity as a latent proenzyme from the conditioned medium of a human rectal carci noma cell line CaR-1. This enzyme hydrolyzed casein more potently than gelatin embedded in polyacrylamide gels in zymography assay. Calcium ion was essential for the activity. It exerted the maximum activity at pH 7-9. Its activity was stimulated by organomercurials, such as p-aminophenyl mercuric acetate and p-chloromercuric benzoic acid, and was inhibited by 1,10-phenanthroline but was hardly affected by diisopropyl fluorophosphate and pepstatin. When the purified proenzyme was acti vated by the organomercurials, it effectively hydrolyzed fibronectin, laminin, type IV basement membrane collagen, and several types of gelatins but not interstitial type I and III collagens. The treatment of the purified proenzyme with /7-aminophenyl mercuric acetate or trypsin formed an active peptide with M, 20,000. The structural analysis indi cated that it was most likely identical to putative metalloproteinase-1, the complementary DNA of which had been cloned from human tumor mRNAs capable of hybridizing to a rat transin complementary DNA. Based on the fact that this enzyme is secreted extracellularly and degrades the matrix proteins, we propose the name "matrin" for this newly