Abstract 367: Aberrant expression of TFPI-1 associated with low procoagulant activity of liver cancer cells.

Abstract

Abstract Background: Coagulation factor VII (fVII) is the key triggering enzyme of the extrinsic blood coagulation pathway. Tissue factor (TF) is the essential cofactor of activated fVII (fVIIa) and widely expressed in normal and cancerous tissues in humans. In addition, evidences are increasing that the TF/fVIIa complex also initiates key pathogenetic mechanisms in cancer unrelated to coagulation, including angiogenesis, cell migration /invasion or survival. Hepatocytes are the predominant source of fVII under normal physiological conditions.Hepatocytes and sinusoidal endothelial cells do not express TF, and no coagulation is activated in the sinusoid or in the space of Disse. In contrast, we demonstrated that some cancer cells aberrantly express both TF and fVII, and the extrinsic coagulation is autonomously triggered on the surface of these cells in vitro. It is not clear whether hepatic cancer (HC) cells derived from hepatocytes express these coagulation factors to exhibit procoagulant activity. Methods: We analyzed expression of TF and fVII by western blotting (WB) with both cell lysate and conditioned medium prepared from various cancer cell lines. We also performed activated coagulation factor X generation analysis to know procoagulant activity on the surface of these cells. Mechanisms that may affect procoagulant activity of HC cells were further examined. Expression of TF and related proteins in surgically removed normal and cirrhotic liver tissues and in hepatocellular carcinoma tissues were also evaluated by western blotting and immunohistochemistry (IHC). Results: Unexpectedly procoagulant activity of HC cells was very low regardless of both TF and abundant fVII expressions. We also found that TFPI-1, an endogenous anticoagulant working on the TF/fVIIa complex, is highly expressed in the HC cell lines and clinical samples of hepatocellular carcinomas. Normal hepatocytes or sinusoidal endothelial cells were devoid of TF nor TFPI-1 expression examined by western blotting and IHC. It was revealed that ectopically synthesized TFPI-1 is responsible for low procoagulant activity of HC cells in spite of the both TF and fVII production. We speculated that the HC cells got some preferable phenotypes by expressing active TF/fVIIa complex unrelated to coagulation in the course of carcinogenesis or progression, and to avoid coagulation and loss of blood supply, they further got to produce TFPI-1. The expression of aberrant TFPI-1 may also confer some coagulation unrelated advantages to the HC cells. Our further experiments revealed that the HC cell adhesion to extracellular matrix components can be suppressed by TFPI-1, which might be convenient for locomotion and spread of these cells. Conclusions: Ectopically synthesized TFPI-1 potentially contributes to HC progression through inhibition of coagulation and adhesion. Citation Format: Shin Ito, Shiro Koizume, Yuji Sakuma, Roppei Yamada, Wolfram Ruf, Yasuo Takano, Yohei Miyagi. Aberrant expression of TFPI-1 associated with low procoagulant activity of liver cancer cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 367. doi:10.1158/1538-7445.AM2013-367