Tissue factor mRNA expression in breast carcinoma cells

Tissue factor (TF) activity has been found in tumor cell homogenates and high TF mRNA expression has been observed in metastatic tumor cell lines. TF is responsible for initiating the extrinsic pathway of coagulation. In the present study, TF cDNA was cloned on the basis of high expression of the corresponding mRNA in metastatic MDA-MB-231 breast carcinoma cells, as opposed to its low expression in non-metastatic MCF-7 cells. However, further analyses revealed that TF mRNA was not uniquely expressed in malignant breast carcinoma cells. Thus, high levels of TF mRNA were observed in nonmalignant, immortalized A1N4, MCF-10 and HBL100 breast epithelial cell lines, whereas low levels were observed in 4 breast carcinoma derived cell lines. TF mRNA was analysed in node-negative breast carcinomas by RT-PCR. Strong expression was observed in 10/24 tumors. We conclude that TF expression did not correlate with the malignant potential of the breast cell lines examined and that TF mRNA can be detected in node-negative breast cancers.