Expression of tissue factor mRNA and invasion of blood vessels by tumor cells in non-small cell lung cancer

Purpose. Tissue factor (TF), an initiator of the extrinsic coagulation cascade, is also expressed in a wide range of cancer cells and plays an important role in cancer progression and metastasis, as well as in processes independent of the blood coagulation pathway. For example, by acting as an adhesion molecule enabling tissue invasion, TF may play a key role in the metastatic process and angiogenesis in non-small cell lung cancer (NSCLC). Methods. To further investigate the role of TF on tumor cell invasion in NSCLC, we measured the TF mRNA expression in the tumors of 42 NSCLC patients using real-time quantitative reverse transcription - polymerase chain reaction carried out in a LightCycler. We then compared the TF mRNA expression with histological evidence of invasion of blood and lymphatic vessels by tumor cells. Results. Although there was no significant relationship between the TF mRNA expression and the invasion of lymphatic vessels, the TF mRNA expression was significantly higher in tumors that invaded blood vessels (Log(10) TF mRNA/GAPDH mRNA = 2.16 +/- 0.18) than in those that did not (1.59 +/- 0.16; P = 0.03). Conclusion. These results suggest that TF plays a major role in blood vessel invasion by tumor cells in NSCLC.