Identification of the cathelicidin peptide LL-37 as agonist for the type I insulin-like growth factor receptor

The human cathelicidin antimicrobial protein-18 and its C terminal peptide, LL-37, displays broad antimicrobial activity that is mediated through direct contact with the microbial cell membrane. In addition, recent studies reveal that LL-37 is involved in diverse biological processes such as immunomodulation, apoptosis, angiogenesis and wound healing. An intriguing role for LL-37 in carcinogenesis is also beginning to emerge and the aim of this paper was to explore if and how LL-37 contributes to the signaling involved in tumor development. To this end, we investigated the putative interaction between LL-37 and growth factor receptors known to be involved in tumor growth and progression. Among several receptors tested, LL-37 bound with the highest affinity to insulin-like growth factor 1 receptor (IGF-1R), a receptor that is strongly linked to malignant cellular transformation. Furthermore, this interaction resulted in a dose-dependent phosphorylation and ubiquitination of IGF-1R, with downstream signaling confined to the mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK)-pathway but not affecting phosphatidylinositol 3 kinase/Akt signaling. We found that signaling induced by LL-37 was dependent on the recruitment of β-arrestin to the fully functional IGF-1R and by using mutant receptors we demonstrated that LL-37 signaling is dependent on β-arrestin-1 binding to the C-terminus of IGF-1R. When analyzing the biological consequences of increased ERK activation induced by LL-37, we found that it resulted in enhanced migration and invasion of malignant cells in an IGF-1R/β-arrestin manner, but did not affect cell proliferation. These results indicate that LL-37 may act as a partial agonist for IGF-1R, with subsequent intra-cellular signaling activation driven by the binding of β-arrestin-1 to the IGF-1R. Functional experiments show that LL-37-dependent activation of the IGF-1R signaling resulted in increased migratory and invasive potential of malignant cells

Neutrophils in cancer: neutral no more

Neutrophils are indispensable antagonists of microbial infection and facilitators of wound healing. In the cancer setting, a newfound appreciation for neutrophils has come into view. The traditionally held belief that neutrophils are inert bystanders is being challenged by the recent literature. Emerging evidence indicates that tumours manipulate neutrophils, sometimes early in their differentiation process, to create diverse phenotypic and functional polarization states able to alter tumour behaviour. In this Review, we discuss the involvement of neutrophils in cancer initiation and progression, and their potential as clinical biomarkers and therapeutic targets

Toll-Like Receptor 3 and Suppressor of Cytokine Signaling Proteins Regulate CXCR4 and CXCR7 Expression in Bone Marrow-Derived Human Multipotent Stromal Cells

The use of bone marrow-derived human multipotent stromal cells (hMSC) in cell-based therapies has dramatically increased in recent years, as researchers have exploited the ability of these cells to migrate to sites of tissue injury, inflammation, and tumors. Our group established that hMSC respond to "danger" signals--by-products of damaged, infected or inflamed tissues--via activation of Toll-like receptors (TLRs). However, little is known regarding downstream signaling mediated by TLRs in hMSC.We demonstrate that TLR3 stimulation activates a Janus kinase (JAK) 2/signal transducer and activator of transcription (STAT) 1 pathway, and increases expression of suppressor of cytokine signaling (SOCS) 1 and SOCS3 in hMSC. Our studies suggest that each of these SOCS plays a distinct role in negatively regulating TLR3 and JAK/STAT signaling. TLR3-mediated interferon regulatory factor 1 (IRF1) expression was inhibited by SOCS3 overexpression in hMSC while SOCS1 overexpression reduced STAT1 activation. Furthermore, our study is the first to demonstrate that when TLR3 is activated in hMSC, expression of CXCR4 and CXCR7 is downregulated. SOCS3 overexpression inhibited internalization of both CXCR4 and CXCR7 following TLR3 stimulation. In contrast, SOCS1 overexpression only inhibited CXCR7 internalization.These results demonstrate that SOCS1 and SOCS3 each play a functionally distinct role in modulating TLR3, JAK/STAT, and CXCR4/CXCR7 signaling in hMSC and shed further light on the way hMSC respond to danger signals

Microenvironmental IL1 1 β promotes metastatic colonisation of breast cancer cells in the bone via activation of Wnt-dependent cancer stem cell activity

Dissemination of tumour cells to the bone marrow is an early event in breast cancer, however cells may lie dormant for many years before bone metastases develop. Treatment for bone metastases is not curative, therefore new adjuvant therapies which prevent the colonisation of disseminated cells into metastatic lesions are required. There is evidence that cancer stem cells (CSCs) within breast tumours are capable of metastasis, but the mechanism by which these colonise bone is unknown. Here, we establish that bone marrow-derived IL1β stimulates breast cancer cell colonisation in the bone by inducing intracellular NFkB and CREB signalling in breast cancer cells, leading to autocrine Wnt signalling and CSC colony formation. Importantly, we show that inhibition of this pathway prevents both CSC colony formation in the bone environment, and bone metastasis. These findings establish that targeting IL1β-NFKB/CREB-Wnt signalling should be considered for adjuvant therapy to prevent breast cancer bone metastasis

Tumour macrophages as potential targets of bisphosphonates

Tumour cells communicate with the cells of their microenvironment via a series of molecular and cellular interactions to aid their progression to a malignant state and ultimately their metastatic spread. Of the cells in the microenvironment with a key role in cancer development, tumour associated macrophages (TAMs) are among the most notable. Tumour cells release a range of chemokines, cytokines and growth factors to attract macrophages, and these in turn release numerous factors (e.g. VEGF, MMP-9 and EGF) that are implicated in invasion-promoting processes such as tumour cell growth, flicking of the angiogenic switch and immunosuppression. TAM density has been shown to correlate with poor prognosis in breast cancer, suggesting that these cells may represent a potential therapeutic target. However, there are currently no agents that specifically target TAM's available for clinical use

Human antimicrobial protein hCAP18/LL-37 promotes a metastatic phenotype in breast cancer

International audienc

ACKR2 in hematopoietic precursors as a checkpoint of neutrophil release and anti-metastatic activity

Italian Association for Cancer Research (AIRC—IG 15438) to R.B. and in part by a grant from the Italian Ministry of Health (GR-2010-2307975) to F.F. and by a grant HEALTH-F4-2011-281608 (TIMER) to A.M.. L.C. is recipient of a fellowship from Fondazione Nicola del Roscio

Anti-tumour activity of bisphosphonates in preclinical models of breast cancer

There is increasing evidence of anti-tumour effects of bisphosphonates from pre-clinical studies, supporting a role for these drugs beyond their traditional use in treatment of cancer-induced bone disease. A range of model systems have been used to investigate the effects of different bisphosphonates on tumour growth, both in bone and at peripheral sites. Most of these studies conclude that bisphosphonates cause a reduction in tumour burden, but that early intervention and the use of high and/or repeated dosing is required. Successful eradication of cancer may only be achievable by targeting the tumour cells directly whilst also modifying the tumour microenvironment. In line with this, bisphosphonates are demonstrated to be particularly effective at reducing breast tumour growth when used in combination with agents that directly target cancer cells. Recent studies have shown that the effects of bisphosphonates on breast tumours are not limited to bone, and that prolonged anti-tumour effects may be achieved following their inclusion in combination therapy. This has opened the field to a new strand of bisphosphonate research, focussed on elucidating their effects on cells and components of the local, regional and distal tumour microenvironment. This review highlights the recent developments in relation to proposed anti-tumour effects of bisphosphonates reported from in vitro and in vivo models, and summarises the data from key breast cancer studies. Evidence for effects on different processes and cell types involved in cancer development and progression is discussed, and the main outstanding issues identified

Local iron homeostasis in the breast ductal carcinoma microenvironment

Abstract BACKGROUND: While the deregulation of iron homeostasis in breast epithelial cells is acknowledged, iron-related alterations in stromal inflammatory cells from the tumor microenvironment have not been explored. METHODS: Immunohistochemistry for hepcidin, ferroportin 1 (FPN1), transferrin receptor 1 (TFR1) and ferritin (FT) was performed in primary breast tissues and axillary lymph nodes in order to dissect the iron-profiles of epithelial cells, lymphocytes and macrophages. Furthermore, breast carcinoma core biopsies frozen in optimum cutting temperature (OCT) compound were subjected to imaging flow cytometry to confirm FPN1 expression in the cell types previously evaluated and determine its cellular localization. RESULTS: We confirm previous results by showing that breast cancer epithelial cells present an 'iron-utilization phenotype' with an increased expression of hepcidin and TFR1, and decreased expression of FT. On the other hand, lymphocytes and macrophages infiltrating primary tumors and from metastized lymph nodes display an 'iron-donor' phenotype, with increased expression of FPN1 and FT, concomitant with an activation profile reflected by a higher expression of TFR1 and hepcidin. A higher percentage of breast carcinomas, compared to control mastectomy samples, present iron accumulation in stromal inflammatory cells, suggesting that these cells may constitute an effective tissue iron reservoir. Additionally, not only the deregulated expression of iron-related proteins in epithelial cells, but also on lymphocytes and macrophages, are associated with clinicopathological markers of breast cancer poor prognosis, such as negative hormone receptor status and tumor size. CONCLUSIONS: The present results reinforce the importance of analyzing the tumor microenvironment in breast cancer, extending the contribution of immune cells to local iron homeostasis in the tumor microenvironment context.info:eu-repo/semantics/publishedVersio

Evidence of an Antimicrobial-Immunomodulatory Role of Atlantic Salmon Cathelicidins during Infection with Yersinia ruckeri

Cathelicidins are a family of antimicrobial peptides that act as effector molecules of the innate immune system with broad-spectrum antimicrobial properties. These evolutionary conserved cationic host-defence peptides are integral components of the immune response of fish, which are generally believed to rely heavily on innate immune defences to invading pathogens. In this study we showed that Atlantic salmon cathelicidin 1 and 2 (asCATH1 and asCATH2) stimulated peripheral blood leukocytes increasing the transcription of the chemokine interleukin-8. Further, functional differences were identified between the two cathelicidins. In the presence of serum, asCATH1 displayed greatly diminished host haemolytic activity, while the constitutively expressed asCATH2 had no haemolytic activity with or without serum. These findings support our hypothesis that fish cathelicidins exert their primary antimicrobial action at the site of pathogen invasion such as epithelial surfaces. Further, we hypothesise that like their mammalian counterparts in the presence of serum they act as mediators of the innate and adaptive immune response via the release of cytokines thus indirectly protecting against a variety of pathogens. We highlight the importance of this immunomodulatory role from the involvement of asCATHs during an infection with the fish pathogen Yersinia ruckeri. While we were able to demonstrate in vitro that asCATH1 and 2, possessed direct microbicidal activity against the fish pathogen, Vibrio anguillarum, and a common gram negative bacterium, Escherichia coli, little or no bactericidal activity was found against Y. ruckeri. The contribution of either asCATH in the immune response or as a potential virulence factor during yersiniosis is highlighted from the increased expression of asCATH1 and 2 mRNA during an in vivo challenge with Y. ruckeri . We propose that Atlantic salmon cathelicidins participate in the interplay between the innate and adaptive immune systems via the release of cytokines enabling a more effective response to invading pathogens