Figure 1

Urokinase plasminogen activator (uPA) immunostaining of paraffin-embedded specimens of human ductal breast cancer tissue and comparison of the staining intensities with uPA levels measured by ELISA. Tissue specimens were formalin fixed for one hour at 4° C and paraffin embedded. Sections (5 μm) were trypsinized, incubated with uPA antibodies that were detected with the avidin biotin complex (ABC) peroxidase technique, developed with 3-amino-9-ethylcarbazole (AEC, red-brown color), and counterstained with Mayers hematoxylin (see “Material and Methods”). A, In the typical example, the strongest immunostaining is seen in paracentral areas (pc in Panel a and magnified in Panel b). Note that the staining is focal and that the periphery (p) and central areas (c) of the tumor show less intense staining (a). uPA immunostaining is seen in stromal cells (s in Panel b) whereas no staining is seen in the cancer cells (ca in Panel b). uPA was detected with the mAb β10 (10 μg/ml). B, Frozen samples from six invasive ductal carcinomas were each divided into two halves. One half was pulverized and processed for uPA ELISA measurements, and the other was formalin fixed and paraffin embedded and used for uPA immunohistochemistry with pAb2 (5 μg/ml). The uPA stained sections were scored by three independent observers as specified in “Material and Methods.” C, The average scores and the corresponding uPA ELISA values are shown. The Spearman rank correlation was 0.90 (p < 0.02). Bars in A: a = 1100 μm, b = 30 μm; B: 100 μm.