Expression of urokinase plasminogen activator (uPA) in the leukocytes and tissues of patients with benign and malignant breast lesions.

OBJECTIVE: to show that the expression of urokinase plasminogen activator (uPA) in the leucocytes of patients with benign and malignant breast lesions correlates with its expression in the lesions, and to explore the role of uPA as a tumour marker in breast cancer.

METHODS: using real time reverse transcriptase - polymerase chain reaction (RT-PCR), we examined the expression of uPA in leukocytes and tissues of three groups of women: a) with breast cancer (BC), b) with benign breast lesions and c) a control group of healthy women. An arbitrary value of 1 was assigned to the level of uPA expressed in the leucocytes of the healthy controls; all other measurements were expressed as a function of this value.

RESULTS: the expression of uPA was significantly higher in BC samples compared to benign breast lesion (5.7 versus 3.8 times; p < 0.001). The leukocyte uPA of healthy volunteers was significantly lower than the leukocyte uPA from patients with breast lesions (p < 0.001). Leukocyte uPA level of patients with BC was higher compared to leukocyte uPA of women with benign lesions (p < 0.01). The expression of tissue uPA was the highest in triple-negative breast cancer. Methylation status was similar across tissue and leukocyte samples.

CONCLUSIONS: leukocyte uPA can be considered a surrogate of the tissue uPA expressed in BC samples. These results further support the use of leukocyte uPA as a biochemical marker of breast cancer.