Determination of the complex between urokinase and its type-1 inhibitor in plasma from healthy donors and breast cancer patients.
BACKGROUND
The complex between urokinase (uPA) and its type-1 inhibitor (PAI-1) is formed exclusively from the active forms of these components; thus, the complex concentration in a biological sample may reflect the ongoing degree of plasminogen activation. Our aim was to establish an ELISA for specific quantification of the uPA:PAI-1 complex in plasma of healthy donors and breast cancer patients.


METHODS
A kinetic sandwich format immunoassay was developed, validated, and applied to plasma from 19 advanced-stage breast cancer patients, 39 age-matched healthy women, and 31 men.


RESULTS
The assay detection limit was <2 ng/L, and the detection of complex in plasma was validated using immunoabsorption, competition, and recovery tests. Eighteen cancer patients had a measurable complex concentration (median, 68 ng/L; range, <16 to 8700 ng/L), whereas for healthy females and males the median signal values were below the detection limit (median, <16 ng/L; range, <16 to 200 ng/L; P <0.0001). For patient plasma, a comparison with total uPA and PAI-1 showed that the complex represented a variable, minor fraction of the uPA and PAI-1 concentrations of each sample.


CONCLUSIONS
The reported ELISA enables detection of the uPA:PAI-1 complex in blood and, therefore, the evaluation of the complex as a prognostic marker in cancer.
Pedersen
A N
AN
The Finsen Laboratory, Rigshospitalet, Strandboulevarden 49, 2100 Copenhagen, Denmark.
Brünner
N
N
Høyer-Hansen
G
G
Hamer
P
P
Jarosz
D
D
Larsen
B
B
Nielsen
H J
HJ
Stephens
R W
RW
D000368:Aged; D014408:Biomarkers, Tumor / Q000097:blood*; D001943:Breast Neoplasms / Q000097:blood* / Q000473:pathology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D017395:Plasminogen Activator Inhibitor 1 / Q000097:blood* / Q000378:metabolism; D011485:Protein Binding; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014568:Urokinase-Type Plasminogen Activator / Q000097:blood* / Q000378:metabolism
D014408:Biomarkers, Tumor; D017395:Plasminogen Activator Inhibitor 1; D014568:Urokinase-Type Plasminogen Activator