TGFβ1-Endo180-dependent collagen deposition is dysregulated at the tumour-stromal interface in bone metastasis

uPARAP/Endo180: a multifaceted protein of mesenchymal cells

The urokinase plasminogen activator receptor-associated protein (uPARAP/Endo180) is already known to be a key collagen receptor involved in collagen internalization and degradation in mesenchymal cells and some macrophages. It is one of the four members of the mannose receptor family along with a macrophage mannose receptor (MMR), a phospholipase lipase receptor (PLA2R), and a dendritic receptor (DEC-205). As a clathrin-dependent endocytic receptor for collagen or large collagen fragments as well as through its association with urokinase (uPA) and its receptor (uPAR), uPARAP/Endo180 takes part in extracellular matrix (ECM) remodeling, cell chemotaxis and migration under physiological (tissue homeostasis and repair) and pathological (fibrosis, cancer) conditions. Recent advances that have shown an expanded contribution of this multifunctional protein across a broader range of biological processes, including vascular biology and innate immunity, are summarized in this paper. It has previously been demonstrated that uPARAP/Endo180 assists in lymphangiogenesis through its capacity to regulate the heterodimerization of vascular endothelial growth factor receptors (VEGFR-2 and VEGFR-3). Moreover, recent findings have demonstrated that it is also involved in the clearance of collectins and the regulation of the immune system, something which is currently being studied as a biomarker and a therapeutic target in a number of cancers.

Identification of Key Modules and Hub Genes of Annulus Fibrosus in Intervertebral Disc Degeneration

Background: Intervertebral disc degeneration impairs the quality of patients lives. Even though there has been development of many therapeutic strategies, most of them remain unsatisfactory due to the limited understanding of the mechanisms that underlie the intervertebral disc degeneration. Questions/purposes: This study is meant to identify the key modules and hub genes related to the annulus fibrosus in intervertebral disc degeneration (IDD) through: (1) constructing a weighted gene co-expression network; (2) identifying key modules and hub genes; (3) verifying the relationships of key modules and hub genes with IDD; and (4) confirming the expression pattern of hub genes in clinical samples. Methods: The Gene Expression Omnibus provided 24 sets of annulus fibrosus microarray data. Differentially expressed genes between the annulus fibrosus of degenerative and non-degenerative intervertebral disc samples have gone through the Gene Ontology (GO) and pathway analysis. The construction of a gene network and classification of genes into different modules were conducted through performing Weighted Gene Co-expression Network Analysis. The identification of modules and hub genes that were most related to intervertebral disc degeneration was proceeded. In order to verify the relationships of the module and hub genes with intervertebral disc degeneration, Ingenuity Pathway Analysis was operated. Clinical samples were adopted to help verify the hub gene expression profile. Results: One thousand one hundred ninety differentially expressed genes were identified. Terms and pathways associated with intervertebral disc degeneration were presented by GO and pathway analysis. The construction of a Weighted Gene Coexpression Network was completed and clustering differentially expressed genes into four modules was also achieved. The module with the lowest P-value and the highest absolute correlation coefficient was selected and its relationship with intervertebral disc degeneration was confirmed by Ingenuity Pathway Analysis. The identification of hub genes and the confirmation of their expression profile were also realized. Conclusions: This study generated a comprehensive overview of the gene networks underlying annulus fibrosus in intervertebral disc degeneration. Clinical Relevance: Modules and hub genes identified in this study are highly associated with intervertebral disc degeneration, and may serve as potential therapeutic targets for intervertebral disc degeneration.

Mathematical modelling of the role of Endo180 network in the development of metastatic bone disease in prostate cancer

Metastatic bone disease (MBD) is a common complication of advanced cancer and recent research suggests that Endo180 expression is dysregulated through the TGFβ-TGFβR-SMAD2/3 signalling pathway during the invasion of tumour cells in the development of MBD. We here provide a model for the dysregulation of the Endo180 network to demonstrate its vital contribution to bone destruction as well as tumour cell growth. The model consisted of a set of ordinary differential equations and reconstructed variations in the bone cells, resultant bone volume, and biochemical factors involved in the TGFβ-TGFβR-SMAD2/3 signalling pathway over time. The model also investigated the underlying mechanism in which the change of TGFβ affects the TGFβ-TGFβR-SMAD2/3 signalling pathway and the resultant Endo180 expression in osteoblastic and tumour cells. The model links the appearance of tumour cells with the inhibition of TGFβ binding to its receptors on osteoblastic cells, to affect TGFβ-TGFβR-SMAD2/3 signalling and Endo180 expression. Temporal variation in bone cells, bone volume, and the biochemical factors involved in the TGFβ-TGFβR-SMAD2/3 pathway as demonstrated in the model simulations agree with published experimental data. The model can be refined based on further discoveries but allows the influence of Endo180 network dysregulation on bone remodelling in MBD to be established. This model could aid in the development of Endo180 targeted therapies for MBD in the future.

Concise Review: Prostate Cancer Stem Cells: Current Understanding

Prostate cancer (PCa) is heterogeneous, harboring phenotypically diverse cancer cell types. PCa cell heterogeneity is caused by genomic instability that leads to the clonal competition and evolution of the cancer genome and by epigenetic mechanisms that result in subclonal cellular differentiation. The process of tumor cell differentiation is initiated from a population of prostate cancer stem cells (PCSCs) that possess many phenotypic and functional properties of normal stem cells. Since the initial reports on PCSCs in 2005, there has been much effort to elucidate their biological properties, including unique metabolic characteristics. In this Review, we discuss the current methods for PCSC enrichment and analysis, the hallmarks of PCSC metabolism, and the role of PCSCs in tumor progression. Stem Cells 2018;36:1457-1474.

Differential Proteomic Analysis Predicts Appropriate Applications for the Secretome of Adipose-Derived Mesenchymal Stem/Stromal Cells and Dermal Fibroblasts

The adult stem cell secretome is currently under investigation as an alternative to cell-based therapy in regenerative medicine, thanks to the remarkable translational opportunity and the advantages in terms of handling and safety. In this perspective, we recently demonstrated the efficient performance of the adipose-derived mesenchymal stem/stromal cell (ASC) secretome in contrasting neuroinflammation in a murine model of diabetic neuropathy, where the administration of factors released by dermal fibroblasts (DFs) did not exert any effect. Up to now, the complex mixture of the constituents of the conditioned medium from ASCs has not been fully deepened, although its appropriate characterization is required in the perspective of a clinical use. Herein, we propose the differential proteomic approach for the identification of the players accounting for the functional effects of the cell secretome with the aim to unravel its appropriate applications. Out of 967 quantified proteins, 34 and 62 factors were found preponderantly or exclusively secreted by ASCs and DFs, respectively. This approach led to the recognition of distinct functions related to the conditioned medium of ASCs and DFs, with the former being involved in the regulation of neuronal death and apoptosis and the latter in bone metabolism and ossification. The proosteogenic effect of DF secretome was validated in vitro on human primary osteoblasts, providing a proof of concept of its osteoinductive potential. Besides discovering new applications of the cell type-specific secretome, the proposed strategy could allow the recognition of the cocktail of bioactive factors which might be responsible for the effects of conditioned media, thus providing a solid rationale to the implementation of a cell-free approach in several clinical scenarios involving tissue regeneration.

Endo180 at the cutting edge of bone cancer treatment and beyond

Skeletal bone is an attractive site for secondary tumour growth and is also home to spontaneous primary cancer. Treatment of bone metastasis is focused on limiting the vicious cycle of bone destruction with bisphosphonates or inhibition of receptor activator of nuclear factor‐κB ligand (RANKL) with the fully human monoclonal antibody denosumab. The estimated 1 million deaths/year where bone metastasis is present, and the high healthcare costs required for its management, have ignited intensive research into the cellular and molecular pathology of osteolysis, involving interplay between tumour cells, bone‐forming osteoblasts and bone‐degrading osteoclasts. Compared to bone metastasis, knowledge about the pathology of primary bone cancers is limited. In recent work published in this journal, Engelholm et al provide a unique insight into how this poorly understood disease manifests and destroys bone. For the first time they have demonstrated that a mouse monoclonal antibody targeting the collagen receptor Endo180 (CD280, MRC2 uPARAP) can prevent osteolysis and bone destruction in a syngeneic model of advanced osteosarcoma. Their convincing findings make an important contribution towards Endo180‐based therapy being developed as an option for the treatment of bone cancer amongst other malignancies. © 2015 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Targeting a novel bone degradation pathway in primary bone cancer by inactivation of the collagen receptor uPARAP/Endo180

In osteosarcoma, a primary mesenchymal bone cancer occurring predominantly in younger patients, invasive tumour growth leads to extensive bone destruction. This process is insufficiently understood, cannot be efficiently counteracted and calls for novel means of treatment. The endocytic collagen receptor, uPARAP/Endo180, is expressed on various mesenchymal cell types and is involved in bone matrix turnover during normal bone growth. Human osteosarcoma specimens showed strong expression of this receptor on tumour cells, along with the collagenolytic metalloprotease, MT1-MMP. In advanced tumours with ongoing bone degeneration, sarcoma cells positive for these proteins formed a contiguous layer aligned with the degradation zones. Remarkably, osteoclasts were scarce or absent from these regions and quantitative analysis revealed that this scarcity marked a strong contrast between osteosarcoma and bone metastases of carcinoma origin. This opened the possibility that sarcoma cells might directly mediate bone degeneration. To examine this question, we utilized a syngeneic, osteolytic bone tumour model with transplanted NCTC-2472 sarcoma cells in mice. When analysed in vitro, these cells were capable of degrading the protein component of surface-labelled bone slices in a process dependent on MMP activity and uPARAP/Endo180. Systemic treatment of the sarcoma-inoculated mice with a mouse monoclonal antibody that blocks murine uPARAP/Endo180 led to a strong reduction of bone destruction. Our findings identify sarcoma cell-resident uPARAP/Endo180 as a central player in the bone degeneration of advanced tumours, possibly following an osteoclast-mediated attack on bone in the early tumour stage. This points to uPARAP/Endo180 as a promising therapeutic target in osteosarcoma, with particular prospects for improved neoadjuvant therapy.

Tumor-associated Endo180 requires stromal-derived LOX to promote metastatic prostate cancer cell migration on human ECM surfaces

The diverse composition and structure of extracellular matrix (ECM) interfaces encountered by tumor cells at secondary tissue sites can influence metastatic progression. Extensive in vitro and in vivo data has confirmed that metastasizing tumor cells can adopt different migratory modes in response to their microenvironment. Here we present a model that uses human stromal cell-derived matrices to demonstrate that plasticity in tumor cell movement is controlled by the tumor-associated collagen receptor Endo180 (CD280, CLEC13E, KIAA0709, MRC2, TEM9, uPARAP) and the crosslinking of collagen fibers by stromal-derived lysyl oxidase (LOX). Human osteoblast-derived and fibroblast-derived ECM supported a rounded ‘amoeboid-like’ mode of cell migration and enhanced Endo180 expression in three prostate cancer cell lines (PC3, VCaP, DU145). Genetic silencing of Endo180 reverted PC3 cells from their rounded mode of migration towards a bipolar ‘mesenchymal-like’ mode of migration and blocked their translocation on human fibroblast-derived and osteoblast-derived matrices. The concomitant decrease in PC3 cell migration and increase in Endo180 expression induced by stromal LOX inhibition indicates that the Endo180-dependent rounded mode of prostate cancer cell migration requires ECM crosslinking. In conclusion, this study introduces a realistic in vitro model for the study of metastatic prostate cancer cell plasticity and pinpoints the cooperation between tumor-associated Endo180 and the stiff microenvironment imposed by stromal-derived LOX as a potential target for limiting metastatic progression in prostate cancer.

The collagen receptor uPARAP/Endo180 in tissue degradation and cancer (Review)

The collagen receptor uPARAP/Endo180, the product of the MRC2 gene, is a central component in the collagen turnover process governed by various mesenchymal cells. Through the endocytosis of collagen or large collagen fragments, this recycling receptor serves to direct basement membrane collagen as well as interstitial collagen to lysosomal degradation. This capacity, shared only with the mannose receptor from the same protein family, endows uPARAP/Endo180 with a critical role in development and homeostasis, as well as in pathological disruptions of the extracellular matrix structure. Important pathological functions of uPARAP/Endo180 have been identified in various cancers and in several fibrotic conditions. With a particular focus on matrix turnover in cancer, this review presents the necessary background for understanding the function of uPARAP/Endo180 at the molecular and cellular level, followed by an in-depth survey of the available knowledge of the expression and role of this receptor in various types of cancer and other degenerative diseases.

AGE-modified basement membrane cooperates with Endo180 to promote epithelial cell invasiveness and decrease prostate cancer survival

Biomechanical strain imposed by age-related thickening of the basal lamina and augmented tissue stiffness in the prostate gland coincides with increased cancer risk. Here we hypothesized that the structural alterations in the basal lamina associated with age can induce mechanotransduction pathways in prostate epithelial cells (PECs) to promote invasiveness and cancer progression. To demonstrate this, we developed a 3D model of PEC acini in which thickening and stiffening of basal lamina matrix was induced by advanced glycation end-product (AGE)-dependent non-enzymatic crosslinking of its major components, collagen IV and laminin. We used this model to demonstrate that antibody targeted blockade of CTLD2, the second of eight C-type lectin-like domains in Endo180 (CD280, CLEC13E, KIAA0709, MRC2, TEM9, uPARAP) that can recognize glycosylated collagens, reversed actinomyosin-based contractility [myosin-light chain-2 (MLC2) phosphorylation], loss of cell polarity, loss of cell-cell junctions, luminal infiltration and basal invasion induced by AGE-modified basal lamina matrix in PEC acini. Our in vitro results were concordant with luminal occlusion of acini in the prostate glands of adult Endo180(Δ) (Ex2-6/) (Δ) (Ex2-6) mice, with constitutively exposed CTLD2 and decreased survival of men with early (non-invasive) prostate cancer with high epithelial Endo180 expression and levels of AGE. These findings indicate that AGE-dependent modification of the basal lamina induces invasive behaviour in non-transformed PECs via a molecular mechanism linked to cancer progression. This study provides a rationale for targeting CTLD2 in Endo180 in prostate cancer and other pathologies in which increased basal lamina thickness and tissue stiffness are driving factors. © 2014 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Survival Outcome and EMT Suppression Mediated by a Lectin Domain Interaction of Endo180 and CD147

Epithelial cell-cell contacts maintain normal glandular tissue homeostasis, and their breakage can trigger epithelial-to-mesenchymal transition (EMT), a fundamental step in the development of metastatic cancer. Despite the ability of C-type lectin domains (CTLD) to modulate cell-cell adhesion, it is not known if they modulate epithelial adhesion in EMT and tumor progression. Here, the multi-CTLD mannose receptor, Endo180 (MRC2/uPARAP), was shown using the Kaplan-Meier analysis to be predictive of survival outcome in men with early prostate cancer. A proteomic screen of novel interaction partners with the fourth CTLD (CTLD4) in Endo180 revealed that its complex with CD147 is indispensable for the stability of three-dimensional acini formed by nontransformed prostate epithelial cells (PEC). Mechanistic study using knockdown of Endo180 or CD147, and treatment with an Endo180 mAb targeting CTLD4 (clone 39.10), or a dominant-negative GST-CTLD4 chimeric protein, induced scattering of PECs associated with internalization of Endo180 into endosomes, loss of E-cadherin (CDH1/ECAD), and unzipping of cell-cell junctions. These findings are the first to demonstrate that a CTLD acts as a suppressor and regulatory switch for EMT; thus, positing that stabilization of Endo180-CD147 complex is a viable therapeutic strategy to improve rates of prostate cancer survival.

IMPLICATIONS

This study identifies the interaction between CTLD4 in Endo180 and CD147 as an EMT suppressor and indicates that stabilization of this molecular complex improves prostate cancer survival rates.

MRC2 expression correlates with TGFβ1 and survival in hepatocellular carcinoma

MRC2 (Mannose Receptor C Type 2) is a constitutively recycling endocytic receptor belonging to the mannose receptor family, which has been found to be closely involved with cancer metastasis. This study attempted to determine MRC2 expression on hepatocellular carcinoma (HCC) and its significance on postsurgical prognosis of HCCs. The expression of both MRC2 and transforming growth factor (TGFβ1) was detected in tumor tissues and adjacent liver tissues from 96 HCCs by immunohistochemistry staining, and it was found that MRC2 expression in HCC tissues was significantly higher than in adjacent liver tissues. HCCs with higher MRC2 expression had worse prognosis after liver resection. Univariate analysis showed that advanced TNM staging of HCC, higher Edmonson-Steiner classification, intrahepatic metastases, portal vein invasion, higher MRC2 and higher TGFβ1 were the poor prognostic factors. Furthermore, multivariate analysis revealed that intrahepatic metastases, higher MRC2 and higher TGFβ1 were the independent prognostic factors. TGFβ1 treatment up-regulated MRC2 expression, cell migration and invasion of Huh7 cells notably. In addition, knockdown of MRC2 repressed the effect of TGFβ1 on cell migration and invasion. These data suggest that MRC2 overexpression predicts poor prognosis of HCCs after liver resection and MRC2 potentially contributed to TGFβ1-driven up-regulation of cell migration and invasion in HCC.

Differential actions of the endocytic collagen receptor uPARAP/Endo180 and the collagenase MMP-2 in bone homeostasis

A well-coordinated remodeling of uncalcified collagen matrices is a pre-requisite for bone development and homeostasis. Collagen turnover proceeds through different pathways, either involving extracellular reactions exclusively, or being dependent on endocytic processes. Extracellular collagen degradation requires the action of secreted or membrane attached collagenolytic proteases, whereas the alternative collagen degradation pathway proceeds intracellularly after receptor-mediated uptake and delivery to the lysosomes. In this study we have examined the functional interplay between the extracellular collagenase, MMP-2, and the endocytic collagen receptor, uPARAP, by generating mice with combined deficiency of both components. In both uPARAP-deficient and MMP-2-deficient adult mice the length of the tibia and femur was decreased, along with a reduced bone mineral density and trabecular bone quality. An additional decrease in bone length was observed when combining the two deficiencies, pointing to both components being important for the remodeling processes in long bone growth. In agreement with results found by others, a different effect of MMP-2 deficiency was observed in the distinct bone structures of the calvaria. These membranous bones were found to be thickened in MMP-2-deficient mice, an effect likely to be related to an accompanying defect in the canalicular system. Surprisingly, both of the latter defects in MMP-2-deficient mice were counteracted by concurrent uPARAP deficiency, demonstrating that the collagen receptor does not support the same matrix remodeling processes as the MMP in the growth of the skull. We conclude that both uPARAP and MMP-2 take part in matrix turnover processes important for bone growth. However, in some physiological situations, these two components do not support the same step in the growth process.

Endo180 modulation by bisphosphonates and diagnostic accuracy in metastatic breast cancer

Background:

Endo180 (CD280; MRC2; uPARAP)-dependent collagen remodelling is dysregulated in primary tumours and bone metastasis. Here, we confirm the release and diagnostic accuracy of soluble Endo180 for diagnosing metastasis in breast cancer (BCa).

Methods:

Endo180 was quantified in BCa cell conditioned medium and plasma from BCa patients stratified according to disease status and bisphosphonate treatment (n=88). All P-values are from two-sided tests.

Results:

Endo180 is released by ectodomain shedding from the surface of MCF-7 and MDA-MB-231 BCa cell lines. Plasma Endo180 was significantly higher in recurrent/metastatic (1.71±0.87; n=59) vs early/localised (0.92±0.37; n=29) BCa (P<0.0001). True/false-positive rates for metastasis classification were: 85%/50% for the reference standard, CA 15-3 antigen (28 U ml⁻¹); ⩽97%/⩾36% for Endo180; and ⩽97%/⩾32% for CA 15-3 antigen+Endo180. Bisphosphonate treatment was associated with reduced Endo180 levels in BCa patients with bone metastasis (P=0.011; n=42). True/false-positive rates in bisphosphonate-naive patients (n=57) were: 68%/45% for CA 15-3 antigen; ⩽95%/⩾20% for Endo180; and ⩽92%/⩾21% for CA 15-3 antigen+Endo180.

Conclusion:

Endo180 is a potential marker modulated by bisphosphonates in metastatic BCa.