Ph. Jensen et al., CLEAVED INTRACELLULAR PLASMINOGEN-ACTIVATOR INHIBITOR-2 IN HUMAN MYELOLEUKAEMIA CELLS IS A MARKER OF APOPTOSIS, British Journal of Cancer, 70(5), 1994, pp. 834-840
The proteolytic modification of plasminogen activator inhibitor 2 (PAI
-2) was studied during apoptosis in the human promyelocytic leukaemic
NB4 cell line during treatment with the phosphatase inhibitors okadaic
acid and calyculin A as well as the protein synthesis inhibitor cyclo
heximide. The apoptic type of cell death was ascertained by morphologi
cal and biochemical criteria. in cell homogenates PAI-2 was probed by
[I-125]urokinase plasminogen activator (uPA) and detected as a sodium
dodecy] sulphate-stable M(T) 80,000 complex after reducing sodium dode
cy] sulphate-polyacrylamide gel electrophoresis and autoradiography. D
uring apoptosis a smaller (M(r) 70,000) uPA-PAI-2 complex was consiste
ntly detected. The modification was in the PAI-2 moiety, as the [I-125
]uPA tracer could be extracted in its intact form from the complex. Th
us the cleaved PAI-2 isoform is a biochemical marker of apoptosis in t
he promyelocytic NB4 cell line. The modified PAI-2 isoform was also de
tected in homogenates made from purified human mononuclear leukaemic c
ells aspirated from the bone marrow of patients suffering From acute a
nd chronic myeloid leukaemia.