During breast cancer progression, transforming growth factor-beta (TGF-β) switches from acting as a growth inhibitor to become a major promoter of epithelial-mesenchymal transition (EMT), invasion and metastasis. However, the mechanisms involved in this switch are not clear. We found that loss of CCAAT-enhancer binding protein beta (C/EBPβ), a differentiation factor for the mammary epithelium, was associated with signs of EMT in triple-negative human breast cancer, and in invasive areas of mammary tumors in MMTV-PyMT mice. Using an established model of TGF-β-induced EMT in mouse mammary gland epithelial cells, we discovered that C/EBPβ was repressed during EMT by miR-155, an oncomiR in breast cancer. Depletion of C/EBPβ potentiated the TGF-β response towards EMT, and contributed to evasion of the growth inhibitory response to TGF-β. Furthermore, loss of C/EBPβ enhanced invasion and metastatic dissemination of the mouse mammary tumor cells to the lungs after subcutaneous injection into mice. The mechanism by which loss of C/EBPβ promoted the TGF-β response towards EMT, invasion and metastasis, was traced to a previously uncharacterized role of C/EBPβ as a transcriptional activator of genes encoding the epithelial junction proteins E-cadherin and coxsackie virus and adenovirus receptor. The results identify miR-155-mediated loss of C/EBPβ as a mechanism, which promotes breast cancer progression by shifting the TGF-β response from growth inhibition to EMT, invasion and metastasis.

Objective—: Human cytomegalovirus (HCMV) is a widespread pathogen that correlates with various clinical complications, including atherosclerosis. HCMV is released into the circulation during primary infection and periodic viral reactivation, allowing virus–platelet interactions. Platelets are important in the onset and development of atherosclerosis, but the consequences of platelet–HCMV interactions are unclear. Approach and Results—: We studied the effects of HCMV–platelet interactions in blood from healthy donors using the purified clinical HCMV isolate VR1814. We demonstrated that HCMV bound to a Toll-like receptor (TLR) 2–positive platelet subpopulation, which resulted in signal transduction, degranulation, and release of proinflammatory CD40L and interleukin-1β and proangiogenic vascular endothelial–derived growth factor. In mice, murine CMV activated wild-type but not TLR2-deficient platelets. However, supernatant from murine CMV–stimulated wild-type platelets also activated TLR2-deficient platelets, indicating that activated platelets generated soluble mediators that triggered further platelet activation, independent of TLR2 expression. Inhibitor studies, using ADP receptor antagonists and apyrase, revealed that ADP release is important to trigger secondary platelet activation in response to HCMV. HCMV-activated platelets rapidly bound to and activated neutrophils, supporting their adhesion and transmigration through endothelial monolayers. In an in vivo model, murine CMV induced systemic upregulation of platelet–leukocyte aggregates and plasma vascular endothelial–derived growth factor in mice and showed a tendency to enhance neutrophil extravasation in a TLR2-dependent fashion. Conclusions—: HCMV is a well-adapted pathogen that does not induce immediate thrombotic events. However, HCMV–platelet interactions lead to proinflammatory and proangiogenic responses, which exacerbate tissue damage and contribute to atherogenesis. Therefore, platelets might contribute to the effects of HCMV in accelerating atherosclerosis.

Cancer cells sustain their metabolic needs through nutrients and oxygen supplied by the bloodstream. The requirement for tumor angiogenesis has been therapeutically exploited in the clinical setting mainly by means of inhibition of the vascular endothelial growth factor family of ligands and receptors. Despite promising results in preclinical models, the benefits for patients proved to be limited. Inadequate efficacy similarly halted the development of agents impinging on the activity of the activin receptor-like kinase (ALK)1, a member of the transforming growth factor-β superfamily. Notwithstanding its characterization as an endothelial cell marker, the full spectrum of biological processes associated with ALK1 is essentially unexplored. Here, we present data revealing the genetic network associated with ACVRL1 (the gene encoding for ALK1) expression in human cancer tissues. Computational analysis unveiled a hitherto unknown role for ACVRL1 in relation to genes modulating the functionality of the immune cell compartment. Moreover, we generated a signature of 8 genes co-expressed with ACVRL1 across different tumor types and characterized the c-type lectin domain containing protein (CLEC)14A as a potential downstream target of ACVRL1. Considering the lack of reagents for ALK1 detection that has hampered the field to date, our work provides the opportunity to validate the 8-gene signature and CLEC14A as biomarkers for ALK1 activity. Ultimately, this may help revisit the clinical development of already existing ALK1-blocking compounds as precision medicines for cancer.

Objective—: Intimal hyperplasia is considered to be a healing response and is a major cause of vessel narrowing after injury, where migration of vascular progenitor cells contributes to pathological events, including transplant arteriosclerosis. Approach and Results—: In this study, we used a rat aortic–allograft model to identify the predominant cell types associated with transplant arteriosclerosis and to identify factors important in their recruitment into the graft. Transplantation of labeled adventitial tissues allowed us to identify the adventitia as a major source of cells migrating to the intima. RNA microarrays revealed a potential role for monocyte chemoattractant protein 1 (MCP-1), stromal cell–derived factor 1, regulated on activation, normal T cell expressed and secreted, and interferon-inducible protein 10 in the induced vasculopathy. MCP-1 induced migration of adventitial fibroblast cells. CCR2, the receptor for MCP-1, was coexpressed with CD90, CD44, NG2, or sca-1 on mesenchymal stem cells. In vivo experiments using MCP-1–deficient and CCR2-deficient mice confirmed an important role of MCP-1 in the formation of intimal hyperplasia in a mouse model of vascular injury. Conclusions—: The adventitia is a potentially important cellular source that contributes to intimal hyperplasia, and MCP-1 is a potent chemokine for the recruitment of adventitial vascular progenitor cells to intimal lesions.

In hemodialysis patients, a native arteriovenous fistula (AVF) is the preferred form of permanent vascular access. Despite recent improvements, vascular access dysfunction remains an important cause of morbidity in these patients. In this prospective observational cohort study, we evaluated potential risk factors for native AVF dysfunction. We included 68 patients with chronic renal disease stage 5 eligible for AVF construction at the Department of General and Vascular Surgery, Central Clinical Hospital Ministry of Internal Affairs, Warsaw, Poland. Patient characteristics and biochemical parameters associated with increased risk for AVF failure were identified using Cox proportional hazards models. Vessel biopsies were analyzed for inflammatory cells and potential associations with biochemical parameters. In multivariable analysis, independent predictors of AVF dysfunction were the number of white blood cells (hazard ratio [HR] 1.67; 95% confidence interval [CI] 1.24 to 2.25; p<0.001), monocyte number (HR 0.02; 95% CI 0.00 to 0.21; p = 0.001), and red blood cell distribution width (RDW) (HR 1.44; 95% CI 1.17 to 1.78; p16.2% was associated with a significantly reduced AVF patency frequency 24 months after surgery. Immunohistochemical analysis revealed CD45-positive cells in the artery/vein of 39% of patients and CD68-positive cells in 37%. Patients with CD68-positive cells in the vessels had significantly higher white blood cell count. We conclude that RDW, a readily available laboratory value, is a novel prognostic marker for AVF failure. Further studies are warranted to establish the mechanistic link between high RDW and AVF failure.

Cancer metastases into the brain constitute one of the most severe, but not uncommon, manifestations of cancer progression. Several factors control how cancer cells interact with the brain to establish metastasis. These factors include mediators of signaling pathways participating in migration, infiltration of the blood–brain barrier, interaction with host cells (e.g., neurons, astrocytes), and the immune system. Development of novel therapies offers a glimpse of hope for increasing the diminutive life expectancy currently forecasted for patients suffering from brain metastasis. However, applying these treatment strategies has not been sufficiently effective. Therefore, there is a need for a better understanding of the metastasis process to uncover novel therapeutic targets. In this review, we follow the journey of various cancer cells from their primary location through the diverse processes that they undergo to colonize the brain. These processes include EMT, intravasation, extravasation, and infiltration of the blood–brain barrier, ending up with colonization and angiogenesis. In each phase, we focus on the pathways engaging molecules that potentially could be drug target candidates.