Activation of carbonic anhydrase IX by alternatively spliced tissue factor under late-stage tumor conditions

Abstract

Molecules of the coagulation pathway predispose patients to cancer-associated thrombosis and also trigger intracellular signaling pathways that promote cancer progression. The primary transcript of Tissue Factor, the main physiologic trigger of blood clotting, can undergo alternative splicing yielding a secreted variant, termed asTF (alternatively spliced Tissue Factor). asTF is not required for normal hemostasis, but its expression levels positively correlate with advanced tumor stages in several cancers, including pancreatic adenocarcinoma. The asTF-over-expressing pancreatic ductal adenocarcinoma cell line Pt45.P1/asTF+ and its parent cell line Pt45.P1 were tested for growth and mobility under normoxic conditions that model early stage tumors, and in the hypoxic environment of late-stage cancers. asTF over-expression in Pt45.P1 cells conveys increased proliferative ability. According to cell cycle analysis, the major fraction of Pt45.P1/asTF+ cells reside in the dividing G2/M phase of the cell cycle, whereas the parental Pt45.P1 cells are mostly confined to the quiescent G0/G1 phase. asTF over-expression is also associated with significantly higher mobility in cells plated under either normoxia or hypoxia. A hypoxic environment leads to upregulation of Carbonic Anhydrase IX (CAIX), which is more pronounced in Pt45.P1/asTF+ cells. Inhibition of CAIX by the compound U-104 significantly decreases cell growth and mobility of Pt45.P1/asTF+ cells in hypoxia, but not in normoxia. U-104 also reduces the growth of Pt45.P1/asTF+ orthotopic tumors in nude mice. CAIX is a novel downstream mediator of asTF in pancreatic cancer, particularly under hypoxic conditions that model late-stage tumor micro-environment.

The Ratio of Factor VIIa:Tissue Factor Content within Microvesicles Determines the Differential Influence on Endothelial Cells

“…3 4 5 6 7 8 9 TF is capable of initiating cellular signals in cells expressing this protein, and also on exposure of recipient cells to exogenous TF-containing microvesicles. TF signaling can alter the cellular gene expression profile 10 11 and has been demonstrated to include fVIIa activity and protease-activated receptor-2 (PAR2) activation. 12 13 14 15 16 17 18 Furthermore, interaction with β-integrins has also been implicated in inducing cell proliferation.…”

An update on anticancer drug development and delivery targeting carbonic anhydrase IX

“…Recently, U-104 has been demonstrated to be effective in vitro and in vivo models of the pancreatic ductal adenocarcinoma (Pt45.P1/asTF +). U-104 significantly decreased the growth of pancreatic cells in hypoxia but not in normoxia and reduced the tumor growth in mice emphasizing the potential of the compound as a therapeutic agent against CA IX ( Ramchandani et al, 2016 ).…”

Alternative splicing in endothelial cells: novel therapeutic opportunities in cancer angiogenesis

“…Tissue factor (TF) asTF Expression/function Soluble factor, highly expressed in advanced stages of several human cancers [100,101]. Stimulates tumor growth, angiogenesis and metastasis [102].…”

“… Insulin receptor (IR) IR-A Expression/function Pro-proliferative function; overexpressed in tumor vasculature [ 99 ]. Tissue factor (TF) asTF Expression/function Soluble factor, highly expressed in advanced stages of several human cancers [ 100 , 101 ]. Stimulates tumor growth, angiogenesis and metastasis [ 102 ].…”