Plasminogen Activator as a Prognostic Factor in Hernatological Malignancies
E. L. Wilson 1,3, P. Jacobs 2, and L. Oliver 1    Hämatol. Bluttransf. Vol 29

I Department of Clinical Science and Immunology
2 Department of Haematology, University of Cape Town Medical School, Observatory 7925, South Africa
3 Henry Kaplan Award for the best poster Clinical Session


The plasminogen-plasmin system is involved in many physiological processes such as fibrinolysis, tissue remodelling, destruction of intercellular matrix and cell migration [1 ]. Human cells release plasminogen activators of two distinct immunochemical types -urokinase and tissue plasminogen activator [2-4]. The activity of these enzymes in biological systems is regulated by a variety of agents such as hormones, retinoids and tumour promoters [5-11]. It is also regulated by protease inhibitors such as protease nexins [12] and by receptors for the enzyme on the surface of human fibroblasts [ 13]. Leukaemic cells secrete both species of plasminogen activator and patients with acute myeloid leukaemia whose cells release only tissue p1asminogen do not respond to combination chemotherapy [14].


Heparinized blood samples were obtained from 117 patients with acute myeloid leukaemia (AML), from 31 patients with chronic myeloid leukaemia (CML), and from 89 patients with other myeloproliferative disorders. Cells were isolated by centritugation on Ficoll-Hypaque and resuspended in RPMI containing 3% foetal calfserum to give 4 Mio. cells/ml [14]. The medium was harvested by centrifugation 24 h later and stored at -80 °C for analysis of enzyme activity. Plasminogen activators were assayed by measuring the plasminogen-dependent re1ease ofso1uble radioactive fibrin degradation peptides from insoluble 125I-Iabelled fibrin-coated multiwell dishes as previously described [15]. Molecular species of plasminogen activators were identified by electrophoretic and immunochemical procedures as previously described [2].

C.Results and Discussion

Immunochemical analysis showed that granulocytes from 23 normal individuals released urokinase exclusively. Cells from 24/117 patients with AML secreted tissue plasminogen activator, cells from 67/117 patients secreted urokinase, cells from 14/ 117 patients secreted a mixture of both enzymes and cells from 12/117 patients secreted too little enzyme for identification (Table 1). The molecular species of enzyme appeared to have prognostic significance since none of the patients whose cells secreted tissue plasminogen activator entered remission with chemotherapy whereas remission was induced in 80% of patients whose cells secreted urokinase. There was a significant difference in median survival between those patients whose cells secreted tissue plasminogen activator (5 weeks) and those individuals whose cells secreted

Table I. Correlation between clinical outcome and molecular species of plasminogen
activator released by cultured cells from 117 patients with AML

urokinase (32 weeks). No significant differences in age or white blood cell count at the time of presentation were found between those patients whose cells secreted tissue plasminogen activator and urokinase. Cells from approximately 20% of patients with AML secreted tissue plasminogen activator. Cells from 31 patients with CML were examined for ,5pecies of plasminogen activator produced. Cells from 15/31 patients secreted tissue plasminogen activator, cells from only 7/31 secreted urokinase and cells from 9/31 secreted both species of enzyme. Thus, the proportion of patients with CML whose cells secreted tissue plasminogen activator was much higher than in the AML group and cells from only 23% of these individuals secreted urokinase. Cells isolated from 89 patients with other myeloproliferative and preleukaernic disorders have also been investigated. Cells from 47/89 patients secreted tissue plasminogen activator, celI5 from 16/89 patients secreted urokinase and cells from the remainder secreted both enzyme species. Thus, the myeloproliferative disorders contain a far higher percentage of individuals whose cells secrete tissue plasminogen activator the enzyme which is associated with a failure to respond to chemotherapy in patients with AML. This is of interest as it is well known that when patients with CML or myelodysplastic states transform, they have a poor prognosis and do not respond to chemotherapy. We are investigating the plasminogen activator status of our patients with myeloproliferative disorders at regular intervals in order to ascertain whether those patients with tissue plasminogen activator have a worse prognosis than those patients whose cells secrete urokinase. It appears as if the type of plasminogen activator secreted by leukaemic cells cultured in vitro will serve as a useful aid to prognosis for patients with AML and possibly also for patients with other myeloproliferative disorders.


I. Reich E ( 1978) Activation of plasminogen. a general mechanism for producing localized extracellular proteolysis. In. Molecular basis of biological degradative processes. Berlin RD. Herman H, Lefow rH. Tanzer JM (eds). Acadernic, New York. pp 155-169
2 Wilson EL. Becker MLB, Hoal E(J. Dowdle EB ( 1980) Molecular species of plasminogen activators secreted by normal and neoplastic human cells. Cancer Res 40:933
3. Vetterlein D, Bell TE. Young PL, Roblin R (1980) rmmunological quantitation and immunoadsorption of urokinase-like plasmin ogen activators secreted by human cells, J Biol Chem 255:2665
4.Astedt B, Wallen P, Aasted B ( 1979) Occurrence of both urokinase and tissue plasminogen activator in human serninal plasma, Throrn Res 16:463
5. Wigler M, Ford JP, Weinstein IB (1975) Glucocorticoid inhibition of the fibrinolytic activity of tumour cells, In: Rifkin D, Reich E, Shaw E (eds) Proteases in biological control, Cold Spring Harbor, Cold Spring Harbor, N.Y,p849
6. Vassalli JD, Hamilton J, Reich E (1977) Macrophage plasminogen activator; induction of concanavalin A and phorbol myristate acetate. Cell 11:695
7. Ossowski L, Biegel D, Reich E (1979) Mammary plasminogen activator: correlation with involution, hormonal modulation and comparison between normal and neoplastic tissue, Cell 16:929
8, Wilson EL, Dowdle EB ( 1980) Effects of retinoids on normal and neoplastic human cel!s cultured in vitro, Cancer Res 40:4817
9, Wilson EL, Reich E (1978) Plasminogen activator in chick fibroblasts: induction of synthesis by retinoic acid; synergism with viral transformation and phorbol ester. Cell 15:385
10. Wigler M, Weinstein IB (1976) Tumour promoter induces plasminogen activator, Nature 259:232
11. Rifkin D ( 1978) Plasminogen activator synthesis by cultured human ernbryonic lung cells' characterization of the suppressive effect of corticosteroids. J Cell Physiol 97:421
12. Baker JB, Low DA, Simmer RL and Cunningharn DD (1980) Protease-nexin. a cellular component that links thrombin and plasminogen activator and mediates their binding to cel!s, Cell 21:37
13. Hoal EG, Wilson EL, Dowdle EB (1983) The regulation of tissue plasminogen activator activity by human fibroblasts, Cel! 34: 273
14. Wilson EL, Jacobs P, Dowdle EB (1983) The secretion of plasminogen activators by human myeloid leukernic cel!s in vitro, Blood 61:568
15. Wilson EL, Dowdle E (1978) Secretion of plasminogen activator by normal reactive and neoplastic human tissues cultured in vitro. Int J Cancer 22: 390