Cholangiocarcinoma (CCA) is characterized by an abundant stromal reaction. Cancer-associated fibroblasts (CAF) are pivotal players in tumor growth and invasiveness and represent a potential therapeutic target. To understand the mechanisms leading to CAF recruitment in CCA, we studied: 1) the expression of epithelial-mesenchymal transition (EMT) in surgical CCA specimens and CCA cells; 2) the lineage tracking of an EGFP-expressing human male CCA cell line (EGI-1) after xenotransplantation into severe-combined-immunodeficient mice; 3) the expression of platelet-derived growth factors (PDGFs) and their receptors in vivo and in vitro; 4) the secretion of PDGFs by CCA cells; 5) the role of PDGF-D in fibroblast recruitment in vitro; 6) the downstream effectors of PDGF-D signaling. CCA cells expressed several EMT biomarkers but not α-SMA. Xenotransplanted CCA masses were surrounded and infiltrated by α-SMA-expressing CAF, which were negative for EGFP and the human Y-probe, but positive for the murine Y-probe. CCA cells were strongly immunoreactive for PDGF-A and -D, whilst CAF expressed PDGFRβ. PDGF-D, a PDGFRβ agonist, was exclusively secreted by cultured CCA cells. Fibroblast migration was potently induced by PDGF-D and CCA conditioned medium, and was significantly inhibited by PDGFRβ blockade with Imatinib and by silencing PDGF-D expression in CCA cells. In fibroblasts, PDGF-D activated the Rac1 and Cdc42 Rho GTPases and JNK. Selective inhibition of Rho GTPases (particularly Rac1) and of JNK strongly reduced PDGF-D-induced fibroblast migration. Conclusion CCA cells express several mesenchymal markers, but do not transdifferentiate into CAF. Instead, CCA cells recruit CAF by secreting PDGF-D, which stimulates fibroblast migration via PDGFRβ and Rho GTPase and JNK activation. Targeting tumor/stroma interactions with inhibitors of PDGF-D pathway may offer a novel therapeutic approach.

Cholangiocarcinoma (CCA) carries a severe prognosis because of its strong invasiveness and early metastasization. In several patients, otherwise eligible for surgical resection, micrometastasis are already present at the time of surgery. The mechanisms responsible for CCA invasiveness are unclear. S100A4, a member of the S100 family of small Ca2+-binding proteins, is expressed in mesenchymal cells, regulates cell motility in several cell types, and is expressed in some epithelial cancers. Thus, we aimed to study the role of S100A4 in CCA invasiveness and metastasization. The expression of S100A4 was studied by immunohistochemistry in 93 human liver samples of CCA patients undergoing surgical resection and correlated with metastases development (67 cases) and patient survival following surgery using log rank tests and multivariate analysis. S100A4 expression was studied in EGI-1 and TFK-1, human CCA cell lines with and without nuclear S100A4 expression, respectively. Metastatic properties of CCA cells were assessed by xenotransplantation in severe combined immunodeficiency (SCID) mice after transduction with lentiviral vectors encoding firefly luciferase gene. Proliferation, motility (wound healing), invasiveness (Boyden chamber), and metalloproteinases (MMPs) secretion were studied in CCA cells, with or without lentiviral silencing of S100A4. Nuclear expression of S100A4 by neoplastic ducts was a strong predictor of metastasization and reduced survival after resection (P < 0.01). EGI-1 CCA cells showed stronger metastatic properties than TFK-1 when xenotransplanted in SCID mice. S100A4-silenced EGI-1 cells showed significantly reduced motility, invasiveness, and MMP-9 secretion in vitro, without changes in cell proliferation. Conclusion Nuclear S100A4 identifies a subset of CCA patients with a poor prognosis after surgical resection. Nuclear expression of S100A4 increases CCA cells invasiveness and metastasization, indicating that S100A4 may also represent a potential therapeutic target.

Nuclear expression of the calcium-binding protein S100A4 is a biomarker of increased invasiveness in cholangiocarcinoma (CCA), a primary liver cancer with scarce treatment opportunities and dismal prognosis. In this study, we provide evidence that targeting S100A4 nuclear import by low dose paclitaxel (PTX), a microtubule stabilizing agent, inhibits CCA invasiveness and metastatic spread. Administration of low dose PTX to established (EGI-1) and primary (CCA-TV3) CCA cell lines expressing nuclear S100A4 triggered a marked reduction in nuclear expression of S100A4 without modifying its cytoplasmic levels, an effect associated with a significant decrease in cell migration and invasiveness. While low dose PTX did not affect cellular proliferation, apoptosis or cytoskeletal integrity, it significantly reduced SUMOylation of S100A4, a critical posttranslational modification that directs its trafficking to the nucleus. This effect of lose dose PTX was reproduced by ginkolic acid, a specific SUMOylation inhibitor. Downregulation of nuclear S100A4 by low dose PTX was associated with a strong reduction in RhoA and Cdc42 GTPase activity, MT1-MMP expression and MMP-9 secretion. In a SCID mouse xenograft model, low dose metronomic PTX treatment decreased lung dissemination of EGI-1 cells without significantly affecting their local tumor growth. In the tumor mass, nuclear S100A4 expression by CCA cells was significantly reduced, whereas rates of proliferation and apoptosis were unchanged. Overall, our findings highlight nuclear S100A4 as a candidate therapeutic target in CCA and establish a mechanistic rationale for the use of low dose PTX in blocking metastatic progression of cholangiocarcinoma.

In patients with type 2 diabetes (T2D) and critical limb ischemia (CLI), migration of circulating CD34 1 cells predicted cardiovascular mortality at 18 months after revascularization. This study aimed to provide long-term validation and mechanistic understanding of the biomarker. RESEARCH DESIGN AND METHODS The association between CD34 1 cell migration and cardiovascular mortality was reassessed at 6 years after revascularization. In a new series of T2D-CLI and control subjects, immuno-sorted bone marrow CD34 1 cells were profiled for miRNA expression and assessed for apoptosis and angiogenesis activity. The differentially regulated miRNA-21 and its proapoptotic target, PDCD4, were titrated to verify their contribution in transferring damaging signals from CD34 1 cells to endothelial cells. RESULTS Multivariable regression analysis confirmed that CD34 1 cell migration forecasts long-term cardiovascular mortality. CD34 1 cells from T2D-CLI patients were more apoptotic and less proangiogenic than those from control subjects and featured miRNA-21 downregulation, modulation of several long noncoding RNAs acting as miRNA-21 sponges, and upregulation of the miRNA-21 proapoptotic target PDCD4. Silencing miR-21 in control CD34 1 cells phenocopied the T2D-CLI cell behavior. In coculture, T2D-CLI CD34 1 cells imprinted naive endothelial cells, increasing apoptosis, reducing network formation, and modulating the TUG1 sponge/miRNA-21/PDCD4 axis. Silencing PDCD4 or scavenging reactive oxygen species protected endothelial cells from the negative influence of T2D-CLI CD34 1 cells. CONCLUSIONS Migration of CD34 1 cells predicts long-term cardiovascular mortality in T2D-CLI patients. An altered paracrine signaling conveys antiangiogenic and proapoptotic features from CD34 1 cells to the endothelium. This damaging interaction may increase the risk for life-threatening complications.

Thrombin activates its G‐coupled seven transmembrane protease‐activated receptor (PAR‐1) by cleaving the receptor's N‐terminal end. In several human cancers, PAR1 expression and activation correlates with tumor progression and metastatization. This provides compelling evidence for the effectiveness of an appropriate antithrombin agent for the adjuvant treatment of patients with cancer. Dabigatran is a selective direct thrombin inhibitor that reversibly binds to thrombin. In this study, we aimed to explore if dabigatran may affect mechanisms favoring tumor growth by interfering with thrombin‐induced PAR‐1 activation.We confirmed that exposure of tumor cells to thrombin significantly increased cell proliferation and this was coupled with downregulation of p27 and concomitant induction of cyclin D1. Dabigatran was consistently effective in antagonizing thrombin‐induced proliferation as well as it restored the baseline pattern of cell cycle protein expression. Thrombin significantly upregulated the expression of proangiogenetic proteins like Twist and GRO‐α in human umbilical vascular endothelial cells (HUVEC) cells and their expression was significantly brought down to control levels when dabigatran was added to culture. We also found that the chemoattractant effect of thrombin on tumor cells was lost in the presence of dabigatran, and that the thrombin antagonist was effective in dampening vascular tube formation induced by thrombin. Our data support a role of thrombin in inducing the proliferation, migration, and proangiogenetic effects of tumor cells in vitro. Dabigatran has activity in antagonizing all these effects, thereby impairing tumor growth and progression. In vivo models may help to understand the relevance of this pathway.