The pro-inflammatory peptide LL-37 promotes ovarian tumor progression through recruitment of multipotent mesenchymal stromal cells

Tumor Targeting Group, University of Sheffield School of Medicine, Sheffield, United Kingdom.
Proceedings of the National Academy of Sciences (Impact Factor: 9.67). 03/2009; 106(10):3806-11. DOI: 10.1073/pnas.0900244106
Source: PubMed


Bone marrow-derived mesenchymal stem cells or multipotent mesenchymal stromal cells (MSCs) have been shown to engraft into the stroma of several tumor types, where they contribute to tumor progression and metastasis. However, the chemotactic signals mediating MSC migration to tumors remain poorly understood. Previous studies have shown that LL-37 (leucine, leucine-37), the C-terminal peptide of human cationic antimicrobial protein 18, stimulates the migration of various cell types and is overexpressed in ovarian, breast, and lung cancers. Although there is evidence to support a pro-tumorigenic role for LL-37, the function of the peptide in tumors remains unclear. Here, we demonstrate that neutralization of LL-37 in vivo significantly reduces the engraftment of MSCs into ovarian tumor xenografts, resulting in inhibition of tumor growth as well as disruption of the fibrovascular network. Migration and invasion experiments conducted in vitro indicated that the LL-37-mediated migration of MSCs to tumors likely occurs through formyl peptide receptor like-1. To assess the response of MSCs to the LL-37-rich tumor microenvironment, conditioned medium from LL-37-treated MSCs was assessed and found to contain increased levels of several cytokines and pro-angiogenic factors compared with controls, including IL-1 receptor antagonist, IL-6, IL-10, CCL5, VEGF, and matrix metalloproteinase-2. Similarly, Matrigel mixed with LL-37, MSCs, or the combination of the two resulted in a significant number of vascular channels in nude mice. These data indicate that LL-37 facilitates ovarian tumor progression through recruitment of progenitor cell populations to serve as pro-angiogenic factor-expressing tumor stromal cells.

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Available from: Heather LaMarca Machado, Jan 23, 2014
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    • "In addition to acquire a lymphatic phenotype in vitro and induce lymphatic regeneration in vivo [48], MSC can directly take part to vessel formation by transdifferentiation into endothelial cells and incorporation into the vessel wall [4], [49]. Furthermore, they can secrete several factors implicated in angiogenesis such as VEGF-A, angiopoietin-1 and bFGF [20], [50]. The indirect pro-angiogenic effects are for instance related to the secretion of interleukin-6 by MSC that induces endothelin-1 production by cancer cells and thereby enhances endothelial cell recruitment and activation [51]. "
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    ABSTRACT: It is now well accepted that multipotent Bone-Marrow Mesenchymal Stem Cells (BM-MSC) contribute to cancer progression through several mechanisms including angiogenesis. However, their involvement during the lymphangiogenic process is poorly described. Using BM-MSC isolated from mice of two different backgrounds, we demonstrate a paracrine lymphangiogenic action of BM-MSC both in vivo and in vitro. Co-injection of BM-MSC and tumor cells in mice increased the in vivo tumor growth and intratumoral lymphatic vessel density. In addition, BM-MSC or their conditioned medium stimulated the recruitment of lymphatic vessels in vivo in an ear sponge assay, and ex vivo in the lymphatic ring assay (LRA). In vitro, MSC conditioned medium also increased the proliferation rate and the migration of both primary lymphatic endothelial cells (LEC) and an immortalized lymphatic endothelial cell line. Mechanistically, these pro-lymphangiogenic effects relied on the secretion of Vascular Endothelial Growth Factor (VEGF)-A by BM-MSC that activates VEGF Receptor (VEGFR)-2 pathway on LEC. Indeed, the trapping of VEGF-A in MSC conditioned medium by soluble VEGF Receptors (sVEGFR)-1, -2 or the inhibition of VEGFR-2 activity by a specific inhibitor (ZM 323881) both decreased LEC proliferation, migration and the phosphorylation of their main downstream target ERK1/2. This study provides direct unprecedented evidence for a paracrine lymphangiogenic action of BM-MSC via the production of VEGF-A which acts on LEC VEGFR-2.
    Full-text · Article · Sep 2014 · PLoS ONE
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    • "Inflammation is a common feature of the tumor microenvironment [16], which consists of cytokines, chemokines, and infiltrated leukocytes. MSCs may secrete several different types of mediators including interleukin-10 (IL-10) [17], transforming growth factor-β (TGF-β) [17,18], hepatocyte growth factor (HGF) [18], and vascular endothelial growth factor (VEGF) [19] when exposed to inflammatory cytokines, which has been reported to play an important role in tumor development. "
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    ABSTRACT: Background Mesenchymal stem cells (MSCs) have been reported to play an important role in tumor growth. Inflammation is an important feature of hepatocellular carcinoma (HCC). Certain inflammatory cytokines produced in tumor microenvironment modulate functional activities of MSCs. At the present time, however, the role of MSCs in the development of HCC cell resistance to chemotherapy in the inflammatory microenvironment during tumor growth has not yet been identified. Methods MTT and PI/Annexin V-FITC assay were employed to examine the proliferation and apoptosis of HCC cell lines. The expression of TGF-β are detected by Realtime PCR and Western blot. GFP tagged LC3 expression vector and electron microscopy are utilized to demonstrate the occurrence of autophagy. Results We observed that MSCs pretreated with the combination of IFN-γ and TNF-α induced resistance to chemotherapy in HCC cell lines in both the in vitro and in vivo circumstances. Following exposure to conditioned medium of MSCs that were pre-treated with IFN-γ plus TNF-α, HCC cell line cells underwent autophagy which serves as a protective mechanism for HCC cells to resist the cell toxicity of chemotherapeutic agents. Treatment of HCC cell line cells with autophagy inhibitor effectively reversed the MSCs-induced resistance to chemotherapy in these cells. Stimulation with the combination of IFN-γ and TNF-α provoked expression of TGF-β by MSCs. MSCs-induced chemoresistance in HCC cell lines was correlated with the up-regulation of TGF-β expression by MSCs. Knockdown of TGF-β expression by MSCs with siRNA attenuated MSCs-induced chemoresistance in HCC cells. Conclusions These results suggest that increase in TGF-β expression by MSCs in the inflammatory microenvironment of HCC promotes the development of chemoresistance in HCC cells.
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    • "In this follow-up study we show that despite similar phenotypic modulation different cell lines of a similar cancer type display diverse transcriptomic modifications. The acquisition of an increased metastatic phenotype during the cross talk between cancer and stromal cells is concordant with previous report in ovarian as well as other tumor types [5,6,9,10,15]. Interestingly our approach using two different cell lines associated to a network analysis illustrate that the shift of phenotype will be dependent on the transcriptomic background. "
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    ABSTRACT: The cross talk between the stroma and cancer cells plays a major role in phenotypic modulation. During peritoneal carcinomatosis ovarian cancer cells interact with mesenchymal stem cells (MSC) resulting in increased metastatic ability. Understanding the transcriptomic changes underlying the phenotypic modulation will allow identification of key genes to target. However in the context of personalized medicine we must consider inter and intra tumoral heterogeneity. In this study we used a pathway-based approach to illustrate the role of cell line background in transcriptomic modification during a cross talk with MSC. We used two ovarian cancer cell lines as a surrogate for different ovarian cancer subtypes: OVCAR3 for an epithelial and SKOV3 for a mesenchymal subtype. We co-cultured them with MSCs. Genome wide gene expression was determined after cell sorting. Ingenuity pathway analysis was used to decipher the cell specific transcriptomic changes related to different pro-metastatic traits (Adherence, migration, invasion, proliferation and chemoresistance). We demonstrate that co-culture of ovarian cancer cells in direct cellular contact with MSCs induces broad transcriptomic changes related to enhance metastatic ability. Genes related to cellular adhesion, invasion, migration, proliferation and chemoresistance were enriched under these experimental conditions. Network analysis of differentially expressed genes clearly shows a cell type specific pattern. The contact with the mesenchymal niche increase metastatic initiation and expansion through cancer cells' transcriptome modification dependent of the cellular subtype. Personalized medicine strategy might benefit from network analysis revealing the subtype specific nodes to target to disrupt acquired pro-metastatic profile.
    Full-text · Article · Mar 2014 · Journal of Translational Medicine
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