Enhanced urokinase-type plasminogen activator activity by extracellular matrix protein obtained from highly...

A protein which enhanced urokinase-type plasminogen activator (u-PA) activity was purified from the extracts of extracellular matrix of highly metastatic cell line HAL-8 derived from human lung adenocarcinoma. The protein showed a single band with molecular weight of 65 kDa after the purification by Sephadex G-150 and diethylaminoethyl-cellulose followed by reversed phase separation in a high performance liquid chromatography system. The purified protein in the immobilized conditions enhanced u-PA activity in both plasminogen activation and S-2444 amidolysis by 4.6- and 2.8-fold increases in the second order rate constants (Kcat/K(m)), respectively. This protein was related to neither plasminogen nor single-chain u-PA by the immunological studies and with respect to retention time on reversed phase analysis. These results suggest that the purified material acts as an enhancer of u-PA in extracellular matrix of the cancer cells, inducing an effective tissue destruction and cell invasion and possessing a highly metastatic potential.