Alternatively spliced tissue factor contributes to tumor spread and activation of coagulation in pancreatic ductal adenocarcinoma

Abstract

Alternatively spliced tissue factor (asTF) promotes neovascularization and monocyte recruitment via integrin ligation. While asTF mRNA has been detected in some pancreatic ductal adenocarcinoma (PDAC) cell lines and increased asTF expression can promote PDAC growth in a subcutaneous model, the expression of asTF protein in bona fide PDAC lesions and/or its role in metastatic spread are yet to be ascertained. We here report that asTF protein is abundant in lesional and stromal compartments of the five studied types of carcinoma including PDAC. Analysis of 29 specimens of PDAC revealed detectable asTF in >90% of the lesions with a range of staining intensities. asTF levels in PDAC lesions positively correlated with the degree of monocyte infiltration. In an orthotopic model, asTF-overexpressing high-grade PDAC cell line Pt45P1/asTF+ produced metastases to distal lymph nodes, which stained positive for asTF. PDAC cells stimulated with and/or overexpressing asTF exhibited upregulation of genes implicated in PDAC progression and metastatic spread. Pt45P1/asTF+ cells displayed higher coagulant activity compared to Pt45P1 cells; the same effect was observed for cell-derived microparticles (MPs). Our findings demonstrate that asTF is expressed in PDAC and lymph node metastases and potentiates PDAC spread in vivo. asTF elicits global changes in gene expression likely involved in tumor progression and metastatic dissemination, and it also enhances the pro-coagulant potential of PDAC cells and cell-derived MPs. Thus, asTF may comprise a novel therapeutic target to treat PDAC and, possibly, its thrombotic complications.

Tissue Factor: A Conventional or Alternative Target in Cancer Therapy

“…In 2011, we found that increased amounts of asTF in cell culture media induced migration of THP-1 leukemia cells in vitro (10 ). In line with this, Unruh et al showed that increased asTF expression in pancreatic ductal adenocarcinomas led to the generation of metastases in distal lymph nodes of mice (25 ). In human endothelial cells, van den Berg and colleagues demonstrated that asTFinduced cell migration is mediated via integrin ␣v␤3 interaction (24 ).…”

“…In both studies, the low procoagulant potential of asTF was dependent on its association with phospholipid surfaces in vitro and in vivo (25,26 ). These findings indicate that, if at all, asTF exhibits only low prothrombogenic potential (7,25 ). Thus, the influence of asTF on cancerrelated thrombosis remains unclear.…”

“…Davila et al also found that asTF, which was secreted by pancreatic tumor cells, exhibited low procoagulant activity (26 ). In both studies, the low procoagulant potential of asTF was dependent on its association with phospholipid surfaces in vitro and in vivo (25,26 ). These findings indicate that, if at all, asTF exhibits only low prothrombogenic potential (7,25 ).…”

“…The procoagulant activity of asTF is controversial (7,8,25 ). We found no detectable effect of increased asTF expression on endothelial thrombogenicity (5 ).…”

“…In contrast, Bogdanov and colleagues found that asTF exhibited, at a minimum, low procoagulant activity when exposed to phospholipids in conditioned medium (7 ). Similarly, Unruh et al showed that overexpression of asTF slightly increased the prothrombotic potential of pancreatic ductal adenocarcinoma cells (25 ). Davila et al also found that asTF, which was secreted by pancreatic tumor cells, exhibited low procoagulant activity (26 ).…”