PAR1 signaling on tumor cells limits tumor growth by maintaining a mesenchymal phenotype in pancreatic cancer

Structural basis of tethered agonism and G protein coupling of protease-activated receptors

Protease-activated receptors (PARs) are a unique group within the G protein-coupled receptor superfamily, orchestrating cellular responses to extracellular proteases via enzymatic cleavage, which triggers intracellular signaling pathways. Protease-activated receptor 1 (PAR1) is a key member of this family and is recognized as a critical pharmacological target for managing thrombotic disorders. In this study, we present cryo-electron microscopy structures of PAR1 in its activated state, induced by its natural tethered agonist (TA), in complex with two distinct downstream proteins, the Gq and Gi heterotrimers, respectively. The TA peptide is positioned within a surface pocket, prompting PAR1 activation through notable conformational shifts. Contrary to the typical receptor activation that involves the outward movement of transmembrane helix 6 (TM6), PAR1 activation is characterized by the simultaneous downward shift of TM6 and TM7, coupled with the rotation of a group of aromatic residues. This results in the displacement of an intracellular anion, creating space for downstream G protein binding. Our findings delineate the TA recognition pattern and highlight a distinct role of the second extracellular loop in forming β-sheets with TA within the PAR family, a feature not observed in other TA-activated receptors. Moreover, the nuanced differences in the interactions between intracellular loops 2/3 and the Gα subunit of different G proteins are crucial for determining the specificity of G protein coupling. These insights contribute to our understanding of the ligand binding and activation mechanisms of PARs, illuminating the basis for PAR1's versatility in G protein coupling.

F10 Gene Expression and Ethnic Disparities Present in Papillary Thyroid Carcinoma

Papillary thyroid carcinoma (PTC) presents a significant health concern, particularly among Hispanic women in the United States, who exhibit a disproportionately higher chance of developing an advanced disease when compared to the non-Hispanic population. Emerging evidence suggests coagulation factor X, encoded by the F10 gene, has a potential role in inhibiting cancer cell migration. However, comprehensive investigations into the differential expression patterns of F10 in Hispanic versus non-Hispanic females remain limited. RNA-sequencing data were acquired from the TCGA database for white female patients, 166 non-Hispanic and 25 Hispanic. A statistically significant (p < 0.05) 2.06-fold increase in F10 expression levels was detected in disease-free tumors compared to recurrent PTC tumors. Furthermore, an increase in F10 gene expression levels was also observed, corresponding to approximately a 1.74-fold increase in non-Hispanic patients compared to Hispanic patients. The probability of tumor recurrence was 1.82 times higher in the cohort with low expression of F10 compared to the high-expression cohort, correlating with the lower disease-free rates observed in the Hispanic patient cohort when compared to non-Hispanics. This finding underscores the relevance of ethnic disparities in molecular profiles for understanding cancer susceptibility. Identifying F10 as a potential prognostic biomarker highlights avenues for targeted interventions and contributes to improving diagnostic and treatment strategies for diverse patient populations.

Enhancement of Tumorigenicity, Spheroid Niche, and Drug Resistance of Pancreatic Cancer Cells in Three-Dimensional Culture System

The three-dimensional (3D) cell culture technique has been applied comprehensively as a variable platform for medical research, biochemical signal pathway analysis, and evaluation of anti-tumor treatment response due to an excellent recapitulation of a tumor microenvironment (TME) in the in vitro cultured cancer cells. Pancreatic cancer (PaC) is one of the toughest malignancies with a complex TME and refractory treatment response. To comprehensively study the TME of PaC, there is an eager need to develop a 3D culture model to decompose the cellular components and their cross interactions. Herein, we establish a 3D PaC culture system with cancer stem cell (CSC) and scalability properties. To validate our model, we tested the individual PaC cell and the combined effects with cancer-associated fibroblasts (CAFs) on cancer tumorigenicity, the cellular interaction through the CXCR3/CXCL10 axis, and cellular responses reflection of anti-cancer treatments. With the help of our 3D technology, a simulated malignant spheroid with important stromal populations and TME physiochemical properties may be successfully recreated. It can be used in a wide range of preclinical research and helpful in advancing basic and translational cancer biology.

A targeted genetic modifier screen in Drosophila uncovers vulnerabilities in a genetically complex model of colon cancer

Received on 16 January 2023; accepted on 21 February 2023Kinases are key regulators of cellular signal transduction pathways. Many diseases, including cancer, are associated with global alterations in protein phosphorylation networks. As a result, kinases are frequent targets of drug discovery efforts. However, target identification and assessment, a critical step in targeted drug discovery that involves identifying essential genetic mediators of disease phenotypes, can be challenging in complex, heterogeneous diseases like cancer, where multiple concurrent genomic alterations are common. Drosophila is a particularly useful genetic model system to identify novel regulators of biological processes through unbiased genetic screens. Here, we report 2 classic genetic modifier screens focusing on the Drosophila kinome to identify kinase regulators in 2 different backgrounds: KRAS TP53 PTEN APC, a multigenic cancer model that targets 4 genes recurrently mutated in human colon tumors and KRAS alone, a simpler model that targets one of the most frequently altered pathways in cancer. These screens identified hits unique to each model and one shared by both, emphasizing the importance of capturing the genetic complexity of human tumor genome landscapes in experimental models. Our follow-up analysis of 2 hits from the KRAS-only screen suggests that classical genetic modifier screens in heterozygous mutant backgrounds that result in a modest, nonlethal reduction in candidate gene activity in the context of a whole animal-a key goal of systemic drug treatment-may be a particularly useful approach to identify the most rate-limiting genetic vulnerabilities in disease models as ideal candidate drug targets.

Tissue factor: a neglected role in cancer biology

Tissue factor (TF), an initiator of extrinsic coagulation pathway, is positively correlated with venous thromboembolism (VTE) of tumor patients. Beyond thrombosis, TF plays a vital role in tumor progression. TF is highly expressed in cancer tissues and circulating tumor cell (CTC), and activates factor VIIa (FVIIa), which increases tumor cells proliferation, angiogenesis, epithelial-mesenchymal transition (EMT) and cancer stem cells(CSCs) activity. Furthermore, TF and TF-positive microvesicles (TF⁺MVs) activate the coagulation system to promote the clots formation with non-tumor cell components (e.g., platelets, leukocytes, fibrin), which makes tumor cells adhere to clots to form CTC clusters. Then, tumor cells utilize clots to cause its reducing fluid shear stress (FSS), anoikis resistance, immune escape, adhesion, extravasation and colonization. Herein, we review in detail that how TF signaling promotes tumor metastasis, and how TF-targeted therapeutic strategies are being in the preclinical and clinical trials.

Molecular Landscape of the Coagulome of Oral Squamous Cell Carcinoma

BACKGROUND

Hemostatic complications, ranging from thromboembolism to bleeding, are a significant source of morbidity and mortality in cancer patients. The tumor coagulome represents the multiple genes and proteins that locally contribute to the equilibrium between coagulation and fibrinolysis. We aimed to study the coagulome of Oral Squamous Cell Carcinoma (OSCC) and examine its link to the tumor microenvironment (TME).

METHODS

We used data from bulk tumor DNA/RNA-seq (The Cancer Genome Atlas), single-cell RNA-seq data and OSCC cells in culture.

RESULTS

Among all tumor types, OSCC was identified as the tumor with the highest mRNA expression levels of F3 (Tissue Factor, TF) and PLAU (urokinase type-plasminogen activator, uPA). Great inter- and intra-tumor heterogeneity were observed. Single-cell analyses showed the coexistence of subpopulations of pro-coagulant and pro-fibrinolytic cancer cells within individual tumors. Interestingly, OSCC with high F3 expressed higher levels of the key immune checkpoint molecules CD274/PD-L1, PDCD1LG2/PD-L2 and CD80, especially in tumor dendritic cells. In vitro studies confirmed the particularity of the OSCC coagulome and suggested that thrombin exerts indirect effects on OSCC cells.

CONCLUSIONS

OSCC presents a specific coagulome. Further studies examining a possible negative modulation of the tumor's adaptive immune response by the coagulation process are warranted.

Coagulome and the tumor microenvironment: an actionable interplay

Human tumors often trigger a hypercoagulable state that promotes hemostatic complications, including venous thromboembolism. The recent application of systems biology to the study of the coagulome highlighted its link to shaping the tumor microenvironment (TME), both within and outside of the vascular space. Addressing this link provides the opportunity to revisit the significance of biomarkers of hemostasis and assess the communication between vasculature and tumor parenchyma, an important topic considering the advent of immune checkpoint inhibitors and vascular normalization strategies. Understanding how the coagulome and TME influence each other offers exciting new prospects for predicting hemostatic complications and boosting the effectiveness of cancer treatment.

MALT1 is a Targetable Driver of Epithelial-to-Mesenchymal Transition in Claudin-low, Triple-Negative Breast Cancer

MALT1 is the effector protein of the CARMA/Bcl10/MALT1 (CBM) signalosome, a multi-protein complex that drives pro-inflammatory signaling pathways downstream of a diverse set of receptors. While CBM activity is best known for its role in immune cells, emerging evidence suggests that it plays a key role in the pathogenesis of solid tumors, where it can be activated by selected G protein-coupled receptors (GPCRs). Here, we demonstrated that overexpression of GPCRs implicated in breast cancer pathogenesis, specifically the receptors for Angiotensin II and thrombin (AT1R and PAR1), drove a strong epithelial-to-mesenchymal transition (EMT) program in breast cancer cells that is characteristic of claudin-low, triple-negative breast cancer (TNBC). In concert, MALT1 was activated in these cells and contributed to the dramatic EMT phenotypic changes through regulation of master EMT transcription factors including Snail and ZEB1. Importantly, blocking MALT1 signaling, through either siRNA-mediated depletion of MALT1 protein or pharmacologic inhibition of its activity, was effective at partially reversing the molecular and phenotypic indicators of EMT. Treatment of mice with mepazine, a pharmacologic MALT1 inhibitor, reduced growth of PAR1+, MDA-MB-231 xenografts and had an even more dramatic effect in reducing the burden of metastatic disease. These findings highlight MALT1 as an attractive therapeutic target for claudin-low TNBCs harboring overexpression of one or more selected GPCRs. Implications: This study nominates a GPCR/MALT1 signaling axis as a pathway that can be pharmaceutically targeted to abrogate EMT and metastatic progression in TNBC, an aggressive form of breast cancer that currently lacks targeted therapies.

Protease-activated receptor 1 drives and maintains ductal cell fates in the premalignant pancreas and ductal adenocarcinoma

Pancreatic acinar cells have high plasticity and can transdifferentiate into ductal-like cells. This acinar-to-ductal metaplasia (ADM) contributes to tissue maintenance but may also contribute to the premalignant transformation that can eventually progress to pancreatic ductal adenocarcinoma (PDAC). Macrophages are key players in ADM, and macrophage-secreted matrix metalloproteinase (MMP)-9 induces ADM through yet unknown mechanisms. As we previously identified MMP9 as a novel agonist of protease-activated receptor 1 (PAR1), a receptor that is known to orchestrate the cross-talk between macrophages and tumor cells in PDAC, we here assessed the contribution of PAR1 to pancreatic cell fates. We found that genetic deficiency for PAR1 increases acinar gene expression programs in the healthy pancreas and that PAR1 deficiency limits ductal transdifferentiation in experimental systems for ADM. Moreover, PAR1 silencing in PDAC cells increases acinar marker expression. Changes in PDAC cell lines were associated with a downregulation of known Myc-target genes, and Myc inhibition mimics PAR1 deficiency in enhancing acinar programs in healthy organoids and PDAC cells. Overall, we identify the PAR1-Myc axis as a driver of ductal cell fates in premalignant pancreas and PDAC. Moreover, we show that cellular plasticity is not unique to acinar cells and that ductal regeneration into acinar-like cells is possible even in the context of oncogenic KRAS activation.

Novel positive allosteric modulator of protease-activated receptor 1 promotes skin wound healing in hairless mice

BACKGROUND AND PURPOSE

Protease-activated receptor 1 (PAR1) is a GPCR expressed in several skin cell types, including keratinocyte and dermal fibroblast. PAR1 activation plays a crucial role in the process of skin wound healing such as thrombosis, inflammation, proliferation and tissue repair. In the present study, we identified a novel positive allosteric modulator of PAR1, GB83, and investigated its effect on skin wound healing.

EXPERIMENTAL APPROACH

The enhancement of PAR1 activity by GB83 was measured using Fluo-4 calcium assay. In silico docking analysis of GB83 in PAR1 was performed using dock ligands method (CDOCKER) with CHARMm force field. Effects of GB83 on cell viability and gene expression were observed using MTS assay and quantitative real-time PCRs, respectively. SKH-1 hairless mice were used to investigate the wound healing effect of GB83.

KEY RESULTS

We demonstrated that GB83 did not activate PAR1 by itself but strongly enhanced PAR1 activation by thrombin and PAR1-activating peptide (AP). In silico docking analysis revealed that GB83 can bind to the PAR1 binding site of vorapaxar. GB83 significantly promoted PAR1-mediated cell viability and migration. In addition, the enhancement of PAR1 activity by GB83 strongly increased gene expression of TGF-β, fibronectin and type I collagen in vitro and promoted skin wound healing in vivo.

CONCLUSION AND IMPLICATIONS

Our results revealed that GB83 is the first positive allosteric modulator of PAR1 and it can be a useful pharmacological tool for studying PAR1 and a potential therapeutic agent for skin wound healing.

Endometrial epithelial-mesenchymal transition (EMT) by menstruation-related inflammatory factors during hypoxia

Endometriosis is characterised by inflammation and fibrotic changes. Our previous study using a mouse model showed that proinflammatory factors present in peritoneal haemorrhage exacerbated inflammation in endometriosis-like grafts, at least in part through the activation of prostaglandin (PG) E2 receptor and protease-activated receptor (PAR). In addition, hypoxia is a well-known inducer of fibrosis that may be associated with epithelial-mesenchymal transition (EMT). However, the complex molecular interactions between hypoxia and proinflammatory menstruation-related factors, PGE2 and thrombin, a PAR1 agonist, on EMT in endometriosis have not been fully characterised. To explore the effects of hypoxia and proinflammatory factors on EMT-like changes in endometrial cells, we determined the effects of PGE2 and thrombin (P/T) on EMT marker expression and cell migration in three dimensional cultured human endometrial epithelial cells (EECs) and endometrial stromal cells (ESCs). Treatment of EECs with P/T under hypoxia stimulated cell migration, increased the expression of mesenchymal N-cadherin, vimentin and C-X-C chemokine receptor type 4 (CXCR4), and reduced the expression of epithelial E-cadherin. Furthermore, treatment with C-X-C motif chemokine ligand 12 (CXCL12), a ligand for CXCR4, increased EMT marker expression and cell migration. In ESCs, P/T or oestrogen treatment under hypoxic conditions increased the expression and secretion of CXCL12. Taken together, our data show that hypoxic and proinflammatory stimuli induce EMT, cell migration and inflammation in EECs, which was increased by CXCL12 derived from ESCs. These data imply that inflammatory mediators in retrograde menstrual fluid contribute to ectopic endometrial EMT and migration in the presence of peritoneal hypoxia.

Coagulation Signaling through PAR1 as a Therapeutic Target in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a highly fatal disease with a 5-year survival rate of less than 10% following diagnosis. The aggressive and invasive properties of pancreatic cancer tumors coupled with poor diagnostic options contribute to the high mortality rate since most patients present with late-stage disease. Accordingly, PDAC is linked to the highest rate of cancer-associated venous thromboembolic disease of all solid tumor malignancies. However, in addition to promoting clot formation, recent studies suggest that the coagulation system in PDAC mediates a reciprocal relationship, whereby coagulation proteases and receptors promote PDAC tumor progression and dissemination. Here, upregulation of tissue factor (TF) by tumor cells can drive local generation of the central coagulation protease thrombin that promotes cell signaling activity through protease-activated receptors (PARs) expressed by both tumor cells and multiple stromal cell subsets. Moreover, the TF-thrombin-PAR1 signaling axis appears to be a major mechanism of cancer progression in general and PDAC in particular. Here, we summarize the current literature regarding the role of PAR1 in PDAC and review possibilities for pharmacologically targeting PAR1 as a PDAC therapeutic approach.

Aspirin and antiplatelet treatments in cancer

Platelets have been hypothesized to promote certain neoplastic malignancies; however, antiplatelet drugs are still not part of routine pharmacological cancer prevention and treatment protocols. Paracrine interactions between platelets and cancer cells have been implicated in potentiating the dissemination, survival within the circulation, and extravasation of cancer cells at distant sites of metastasis. Signals from platelets have also been suggested to confer epigenetic alterations, including upregulating oncoproteins in circulating tumor cells, and secretion of potent growth factors may play roles in promoting mitogenesis, angiogenesis, and metastatic outgrowth. Thrombocytosis remains a marker of poor prognosis in patients with solid tumors. Experimental data suggest that lowering of platelet count may reduce tumor growth and metastasis. On the basis of the mechanisms by which platelets could contribute to cancer growth and metastasis, it is conceivable that drugs reducing platelet count or platelet activation might attenuate cancer progression and improve outcomes. We will review select pharmacological approaches that inhibit platelets and may affect cancer development and propagation. We begin by presenting an overview of clinical cancer prevention and outcome studies with low-dose aspirin. We then review current nonclinical development of drugs targeted to platelet binding, activation, and count as potential mitigating agents in cancer.

Doxycycline Inhibits Cancer Stem Cell-Like Properties via PAR1/FAK/PI3K/AKT Pathway in Pancreatic Cancer

Pancreatic cancer stem cells (CSCs) play an important role in the promotion of invasion and metastasis of pancreatic cancer. Protease activation receptor 1 (PAR1) is closely related to malignant progression of tumors, however, its effects on pancreatic cancer stem cell-like (CSC-like) properties formation have not been reported. In this work, the effects of PAR1 on pancreatic cancer stem cell-like (CSC-like) properties formation were studied. PAR1 overexpression can induce CSC-like properties in Aspc-1 cells, whereas interference of PAR1 in Panc-1 cells showed the contrary results. Data on patients with pancreatic cancer obtained from TCGA showed that high PAR1 expression and focal adhesion kinase (FAK) protein considerably affect the prognosis of patients. Further experiments showed that PAR1 could regulate FAK, PI3K, and AKT phosphorylation and the epithelial-mesenchymal transformation (EMT) in Aspc-1 and Panc-1 cells. Doxycycline, as a PAR1 inhibitor, could effectively inhibit the CSC-like properties of pancreatic cancer cells and the FAK/PI3K/AKT pathway activation. Doxycycline inhibits the growth of pancreatic cancer and enhances the treatment effect of 5-fluorouracil (5-FU) in Panc-1 xenograft mouse model. In conclusion, PAR1 promotes the CSC-like properties and EMT of pancreatic cancer cells via the FAK/PI3K/AKT pathway. Doxycycline inhibits the pancreatic cancer through the PAR1/FAK/PI3K/AKT pathway and enhances the therapeutic effect of 5-FU.

Engineering of biomaterials for tumor modeling

Development of biomaterials mimicking tumor and its microenvironment has recently emerged for the use of drug discovery, precision medicine, and cancer biology. These biomimetic models have developed by reconstituting tumor and stroma cells within the 3D extracellular matrix. The models are recently extended to recapitulate the in vivo tumor microenvironment, including biological, chemical, and mechanical conditions tailored for specific cancer type and its microenvironment. In spite of the recent emergence of various innovative engineered tumor models, many of these models are still early stage to be adapted for cancer research. In this article, we review the current status of biomaterials engineering for tumor models considering three main aspects - cellular engineering, matrix engineering, and engineering for microenvironmental conditions. Considering cancer-specific variability in these aspects, our discussion is focused on pancreatic cancer, specifically pancreatic ductal adenocarcinoma (PDAC). In addition, we further discussed the current challenges and future opportunities to create reliable and relevant tumor models.

Elevated expression of protease-activated receptor 1 via ΔNp63 down-regulation contributes to nodal metastasis in oral squamous cell carcinoma

Protease-activated receptor 1 (PAR1) is known as a thrombin receptor. Recent studies have reported PAR1 expression in various malignancies; however, its role in oral squamous cell carcinoma (OSCC) requires clarification. A previous study showed that down-regulation of ΔNp63, a homolog of p53, augments PAR1 expression in OSCC. In the present study, the association of PAR1 expression with clinicopathological findings in OSCC was examined retrospectively. Expression of PAR1, thrombin, and ΔNp63 was examined immunohistochemically in OSCC specimens. Patients were divided into three groups based on the expression pattern of PAR1 at the invasive front: group A, PAR1-negative in both cancer and stromal cells; group B, positive in stromal cells but negative in cancer cells; group C, positive in both cancer and stromal cells. Histologically high-grade tumours were significantly more common in group C. Patients in group C had the highest incidence rate of nodal metastasis (P<0.001) and a lower survival rate (P=0.085) than those in the other groups. At the invasive front, in group C, thrombin was expressed but ΔNp63 expression was weak. These results indicate that increased PAR1 expression in both cancer and stromal cells could be a useful predictive marker of nodal metastasis and that ΔNp63 is involved in regulating PAR1 expression.

GPCRs in pancreatic adenocarcinoma: Contributors to tumour biology and novel therapeutic targets

Pancreatic cancer has one of the highest mortality rates (5-year survival ~9%) among cancers. Pancreatic adenocarcinoma (PAAD) is the most common (>80%) and the most lethal type of pancreatic cancer. A need exists for new approaches to treat pancreatic adenocarcinoma. GPCRs, the largest family of cell-surface receptors and drug targets, account for ~35% of approved drugs. Recent studies have revealed roles for GPCRs in PAAD cells and cells in the tumour micro-environment. This review assesses current information regarding GPCRs in PAAD by summarizing omics data for GPCRs expression in PAAD. The PAAD "GPCRome" includes GPCRs with approved agents, thereby offering potential for their repurposing/repositioning. We then reviewed the evidence for functional roles of specific GPCRs in PAAD. We also highlight gaps in understanding the contribution of GPCRs to PAAD biology and identify several GPCRs that may be novel therapeutic targets for future work in search of GPCR-targeted drugs to treat PAAD tumours.

Macrophage-secreted MMP9 induces mesenchymal transition in pancreatic cancer cells via PAR1 activation

PURPOSE

Targeting tumor-infiltrating macrophages limits progression and improves chemotherapeutic responses in pancreatic ductal adenocarcinoma (PDAC). Protease-activated receptor (PAR)1 drives monocyte/macrophage recruitment, and stromal ablation of PAR1 limits cancer growth and enhances gemcitabine sensitivity in experimental PDAC. However, the functional interplay between PAR1, macrophages and tumor cells remains unexplored. Here we address the PAR1-macrophage-tumor cell crosstalk and assess its contributions to tumor progression.

METHODS

PAR1 expression and macrophage infiltration were correlated in primary PDAC biopsies using gene expression datasets and tissue microarrays. Medium transfer experiments were used to evaluate the functional consequences of macrophage-tumor cell crosstalk and to assess the contribution of PAR1 to the observed responses. PAR1 cleavage assays were used to identify a macrophage-secreted PAR1 agonist, and the effects of candidate proteases were assessed in medium transfer experiments with specific inhibitors and/or recombinant agonist.

RESULTS

PAR1 expression correlates with macrophage infiltration in primary PDACs, and macrophages induce mesenchymal transition of PDAC cells through PAR1 activation. Protease profiling identified macrophage-secreted matrix metalloprotease 9 (MMP9) as the relevant PAR1 agonist in PDAC. PAR1 and/or MMP9 inhibition limited macrophage-driven mesenchymal transition. Likewise, preventing mesenchymal transition by silencing ZEB1 or by pharmacological inhibition of the MMP9/PAR1 axis significantly reduced the ability of tumor cells to survive the anti-tumor activities of macrophages.

CONCLUSION

Macrophages secrete MMP9, which acts upon PDAC cell PAR1 to induce mesenchymal transition. This macrophage-induced mesenchymal transition supports the tumor-promoting role of macrophage influx, explaining the dichotomous contributions of these immune cells to tumor growth.

Rivaroxaban does not affect growth of human pancreatic tumors in mice

BACKGROUND

Some clinical studies have shown that low-molecular-weight heparins (LMWHs) prolong the survival of cancer patients. In addition, various anticoagulants have been shown to reduce growth of tumors in mice. However, there are no studies on the effect of the factor Xa inhibitor rivaroxaban on growth of human pancreatic tumors in nude mice.

OBJECTIVES

To test the hypothesis that the factor Xa inhibitor rivaroxaban reduces the growth of tissue factor (TF)-positive pancreatic tumors but not TF-negative pancreatic tumors in mice.

METHODS

The TF-positive human pancreatic cancer cell line BxPc-3 and the TF-negative human pancreatic cancer cell line MIA PaCa-2 were injected subcutaneously into nude mice and tumors grown to a mean volume of ~100 mm3 . Mice were then divided into two groups. One group was fed chow containing rivaroxaban (0.5 g/kg chow) whereas the other group was fed chow without rivaroxaban.

RESULTS

Rivaroxaban significantly prolonged prothrombin time in tumor-bearing mice. Rivaroxaban did not affect cell proliferation or growth of either BxPc-3 or MIA PaCa-2 tumors grown subcutaneously in nude mice.

CONCLUSION

Our results indicate that inhibition of factor Xa with rivaroxaban does not affect the growth of two human pancreatic tumors in nude mice.

Targeting Epithelial Mesenchymal Plasticity in Pancreatic Cancer: A Compendium of Preclinical Discovery in a Heterogeneous Disease

Pancreatic Ductal Adenocarcinoma (PDAC) is a particularly insidious and aggressive disease that causes significant mortality worldwide. The direct correlation between PDAC incidence, disease progression, and mortality highlights the critical need to understand the mechanisms by which PDAC cells rapidly progress to drive metastatic disease in order to identify actionable vulnerabilities. One such proposed vulnerability is epithelial mesenchymal plasticity (EMP), a process whereby neoplastic epithelial cells delaminate from their neighbours, either collectively or individually, allowing for their subsequent invasion into host tissue. This disruption of tissue homeostasis, particularly in PDAC, further promotes cellular transformation by inducing inflammatory interactions with the stromal compartment, which in turn contributes to intratumoural heterogeneity. This review describes the role of EMP in PDAC, and the preclinical target discovery that has been conducted to identify the molecular regulators and effectors of this EMP program. While inhibition of individual targets may provide therapeutic insights, a single ‘master-key’ remains elusive, making their collective interactions of greater importance in controlling the behaviours’ of heterogeneous tumour cell populations. Much work has been undertaken to understand key transcriptional programs that drive EMP in certain contexts, however, a collaborative appreciation for the subtle, context-dependent programs governing EMP regulation is needed in order to design therapeutic strategies to curb PDAC mortality.

Tissue Factor and Cancer: Regulation, Tumor Growth, and Metastasis

There is a strong relationship between tissue factor (TF) and cancer. Many cancer cells express high levels of both full-length TF and alternatively spliced (as) TF. TF expression in cancer is associated with poor prognosis. In this review, the authors summarize the regulation of TF expression in cancer cells and the roles of TF and asTF in tumor growth and metastasis. A variety of different signaling pathways, transcription factors and micro ribonucleic acids regulate TF gene expression in cancer cells. The TF/factor VIIa complex enhances tumor growth by activating protease-activated receptor 2 signaling and by increasing the expression of angiogenic factors, such as vascular endothelial growth factor. AsTF increases tumor growth by enhancing integrin β1 signaling. TF and asTF also contribute to metastasis via multiple thrombin-dependent and independent mechanisms that include protecting tumor cells from natural killer cells. Finally, a novel anticancer therapy is using tumor TF as a target to deliver cytotoxic drugs to the tumor. TF may be useful in diagnosis, prognosis, and treatment of cancer.

Endothelial Protein C Receptor (EPCR), Protease Activated Receptor-1 (PAR-1) and Their Interplay in Cancer Growth and Metastatic Dissemination

Endothelial protein C receptor (EPCR) and protease activated receptor 1 (PAR-1) by themselves play important role in cancer growth and dissemination. Moreover, interactions between the two receptors are essential for tumor progression. EPCR is a cell surface transmembrane glycoprotein localized predominantly on endothelial cells (ECs). It is a vital component of the activated protein C (APC)—mediated anticoagulant and cytoprotective signaling cascade. PAR-1, which belongs to a family of G protein–coupled cell surface receptors, is also widely distributed on endothelial and blood cells, where it plays a critical role in hemostasis. Both EPCR and PAR-1, generally considered coagulation-related receptors, are implicated in carcinogenesis and dissemination of diverse tumor types, and their expression correlates with clinical outcome of cancer patients. Existing data explain some mechanisms by which EPCR/PAR-1 affects cancer growth and metastasis; however, the exact molecular basis of cancer invasion associated with the signaling is still obscure. Here, we discuss the role of EPCR and PAR-1 reciprocal interactions in cancer progression as well as potential therapeutic options targeted specifically to interact with EPCR/PAR-1-induced signaling in cancer patients.