Fibrinolytic activity associated with cultured human neoplastic and normal cells

Fibrinolytic activity was studied in a number of different established as well as secondary human cell cultures derived from both malignant and normal tissues. The ability to degrade [25I]-labeled fibrin was found to be characteristic of some malignant cultures as well as some normal cultures, and to be dependent upon the presence of serum. For the most part, this activity was detected in cultures with a relatively short in vitro passage history (less than 30 passages). Low passaged colon and rectal carcinoma cells, HCT-8 and HRT-18, as well as normal rectal, colon and foreskin fibroblasts were positive for fibrinolytic activity, while long established (greater than 100 passages) cultures of malignant cells (colon carcinoma, HeLa, Hep-2, KB) as well as normal cells (HEI, AV3) were negative. It is proposed that although some normal cells synthesize plasminogen activators, the fibrinolytic capability of both malignant and normal cells may be lost on prolonged in vitro cultivation.