The plasminogen activator released from primary cultured rat hepatocyte has been recognized to be identical with a biliary plasminogen activator, Bilokinase (BK) in terms of its enzymatic properties (Blood & Vessel 16, 449, 1985).
In the present investigation, we attempted to find out cell lines derived from human liver which produce and release plasminogen activator, and to elucidate the enzymatic properties of these particular plasminogen activator.
The following results were obtained;
1) HuL-1 cell line (derived from fetal liver) was observed not to secrete plasminogen activator (PA). PLC cell line (derived from hepatocellula carcinoma) and KN 73 (derived from hepatitis) were observed to produce a trace amount of PA.
2) HuH-7 cell line (derived from hepatocellular carcinoma) and KN 7-7 cell line (derived from hepatitis) were observed to produce high active PA releasable into culture medium.
3) The molecular weights of two kinds of PA of HuH-7 were 72, 000 and 50, 000, and the molecular weight of single PA of KN 7-7 was 50, 000.
4) The affinity to fibrin of PA of HuH-7 as well as that KN 7-7 were extremely higy. The affinity to lysine of PA of HuH-7 and KN 7-7 were similarly very high. The activity of these PA on fibrinolysis was not inhibited by UK anti-body, but was inhibited by t-PA anti-body. The above properties of PA of HuH-7 and KN 7-7 were so called melanoma t-PA type characteristic.
