TFPI (Tissue Factor Pathway Inhibitor) Is Present in Breast Cancer Tumor Cells.

Abnormalities in hemostatic system are common in breast cancer patients. The principal initiator of blood coagulation activation in cancer patients is tissue factor (TF). Tissue factor plays an important role in the processes of angiogenesis, invasion and metastatic dissemination. Tissue factor pathway inhibitor (TFPI) is the main inhibitor of TF-dependent pathway of blood coagulation. The catalytic activity of the TF/VIIa complex triggers activation of factor X, consequently thrombin generation and finally fibrin formation. Thrombin and fibrin facilitate cancer progression. Previous immunohistochemical studies revealed no expression of TFPI in cancer cells of different malignant tumor types (

Breast cancer tissues were obtained during surgical treatment of 35 women. The patients undergoing surgery had not received any previous anticancer therapy. Tumor fragments were preserved in 4% paraformaldehyde/phosphate buffered saline and than embedded in paraffin. Immunohistochemical studies (avidin-biotin complex-ABC - technique) were performed using polyclonal antibodies against TFPI. In situ hybridization method employed single-stranded DNA oligonucleotide (probe sequence: 5′Biotin-CATCGCCCAGTGCAGCCTCCGTCAG-Biotin3′) directed against locus NM 006287 of TFPI mRNA.

Strong expression of TFPI protein was observed in cancer cell bodies in examined specimens. Weak expression of the above protein was observed in tumor infiltrating macrophages. Normal cells revealed much weaker staining for TFPI than cancer cells. Similarly, mRNA for TFPI was observed in cancer cells of all breast cancer tissues.

The above data indicate that TFPI is present in neoplastic cells of breast cancer and may play a role in neutralizing TF procoagulant and signaling functions.