Host stromal versican is essential for cancer-associated fibroblast function to inhibit cancer growth

Splicing variants of versican in CD133+/CD44+ prostate cancer stem cells

A cancer mass is composed of a heterogeneous group of cells, a small part of which constitutes the cancer stem cells since they are less differentiated and have a high capacity to develop cancer. Versican is an extracellular matrix protein located in many human tissues. The mRNA of versican has been shown to have "splicing patterns" as detected by RT-PCR, northern blot analysis, and cDNA sequencing. Based on this knowledge this study aims to reveal the splice variants of versican molecules, which are thought to be involved in the pathogenesis of the DU-145 human prostatic carcinoma cell line and prostatic cancer stem cells isolated from this cell line. In this study, RWPE-1 normal prostatic and DU-145 human prostate cancer cell lines have been used. Prostatic cancer stem cells and the remaining group of non-prostatic-cancer stem cells (bulk population) were isolated according to their CD133+/CD44+. RNA was isolated in all groups, and sequence analysis was accomplished for splicing variants by Illumina NextSeq 500 sequencing system. The results were analyzed by bioinformatic evaluation. As five isoforms of the versican gene in the differential transcript expression are analyzed, it was observed that a significant change was only found in the isoforms Versican 0 and Versican 1. In this study, we explored the function of this molecule which we think to be effective in cancer progression, and suggested that more valuable results can be obtained after the accomplishment of in vivo experiments.

The hidden messengers: cancer associated fibroblasts-derived exosomal miRNAs as key regulators of cancer malignancy

Cancer-associated fibroblasts (CAFs), a class of stromal cells in the tumor microenvironment (TME), play a key role in controlling cancer cell invasion and metastasis, immune evasion, angiogenesis, and resistance to chemotherapy. CAFs mediate their activities by secreting soluble chemicals, releasing exosomes, and altering the extracellular matrix (ECM). Exosomes contain various biomolecules, such as nucleic acids, lipids, and proteins. microRNA (miRNA), a 22-26 nucleotide non-coding RNA, can regulate the cellular transcription processes. Studies have shown that miRNA-loaded exosomes secreted by CAFs engage in various regulatory communication networks with other TME constituents. This study focused on the roles of CAF-derived exosomal miRNAs in generating cancer malignant characteristics, including immune modulation, tumor growth, migration and invasion, epithelial-mesenchymal transition (EMT), and treatment resistance. This study thoroughly examines miRNA's dual regulatory roles in promoting and suppressing cancer. Thus, changes in the CAF-derived exosomal miRNAs can be used as biomarkers for the diagnosis and prognosis of patients, and their specificity can be used to develop newer therapies. This review also discusses the pressing problems that require immediate attention, aiming to inspire researchers to explore more novel avenues in this field.

Versican core protein aids in the diagnosis and grading of breast phyllodes tumor

Phyllodes tumors (PTs) are biphasic fibroepithelial lesions that occur in the breast. Diagnosing and grading PTs remains a challenge in a small proportion of cases, due to the lack of reliable specific biomarkers. We screened a potential marker versican core protein (VCAN) through microproteomics analysis, validated its role for the grading of PTs by immunohistochemistry, and analyzed the correlation between VCAN expression and clinicopathological characteristics. Cytoplasmic immunoreactivity for VCAN was identified in all benign PT samples, among which 40 (93.0 %) showed VCAN-positive staining in ≥50 % of tumor cells. Eight (21.6 %) borderline PT samples showed VCAN-positive staining in ≥50 % of the cells with weak to moderate staining intensity, whereas 29 samples (78.4 %) showed VCAN-positive staining in <50 % of the cells. In malignant PTs, 16 (84.2 %) and three (15.8 %) samples showed VCAN-positive staining in <5 % and 5-25 % of stromal cells, respectively. Fibroadenomas showed a similar expression pattern to benign PTs. Fisher's exact test showed that the percentages of positive cells (P < .001) and staining intensities (P < .001) of tumor cells were significantly different between the five groups. VCAN positivity was associated with tumor categories (P < .0001) and CD34 expression (P < .0001). The expression of VCAN gradually decreases as the tumor categories increases, following recurrence. To the best of our knowledge, our results are the first in the literature to reveal that VCAN is useful for diagnosing and grading PTs. The expression level of VCAN appeared to be negatively associated with PT categories, suggesting that dysregulation of VCAN may be involved in the tumor progression of PTs.

Cancer-associated fibroblasts and its derived exosomes: a new perspective for reshaping the tumor microenvironment

Cancer-associated fibroblasts (CAFs) are the most abundant stromal cells within the tumor microenvironment (TME). They extensively communicate with the other cells. Exosome-packed bioactive molecules derived from CAFs can reshape the TME by interacting with other cells and the extracellular matrix, which adds a new perspective for their clinical application in tumor targeted therapy. An in-depth understanding of the biological characteristics of CAF-derived exosomes (CDEs) is critical for depicting the detailed landscape of the TME and developing tailored therapeutic strategies for cancer treatment. In this review, we have summarized the functional roles of CAFs in the TME, particularly focusing on the extensive communication mediated by CDEs that contain biological molecules such as miRNAs, proteins, metabolites, and other components. In addition, we have also highlighted the prospects for diagnostic and therapeutic applications based on CDEs, which could guide the future development of exosome-targeted anti-tumor drugs.

Roles of cancer-associated fibroblasts (CAFs) in anti- PD-1/PD-L1 immunotherapy for solid cancers

In recent years, breakthroughs have been made in tumor immunotherapy. However, tumor immunotherapy, particularly anti-PD-1/PD-L1 immune checkpoint inhibitors, is effective in only a small percentage of patients in solid cancer. How to improve the efficiency of cancer immunotherapy is an urgent problem to be solved. As we all know, the state of the tumor microenvironment (TME) is an essential factor affecting the effectiveness of tumor immunotherapy, and the cancer-associated fibroblasts (CAFs) in TME have attracted much attention in recent years. As one of the main components of TME, CAFs interact with cancer cells and immune cells by secreting cytokines and vesicles, participating in ECM remodeling, and finally affecting the immune response process. With the in-depth study of CAFs heterogeneity, new strategies are provided for finding targets of combination immunotherapy and predicting immune efficacy. In this review, we focus on the role of CAFs in the solid cancer immune microenvironment, and then further elaborate on the potential mechanisms and pathways of CAFs influencing anti-PD-1/PD-L1 immunotherapy. In addition, we summarize the potential clinical application value of CAFs-related targets and markers in solid cancers.

Comprehensive Analysis of VCAN Expression Profiles and Prognostic Values in HCC

Background: Hepatocellular carcinoma (HCC) is the world’s most common cause of cancer death. Therefore, more molecular mechanisms need to be clarified to meet the urgent need to develop new detection and treatment strategies.

Methods: We used TCGAportal, Kaplan–Meier Plotter, the Cistrome DB Toolkit Database, MExpress, GEPIA2, and other databases to discuss the expression profiles, possible biological function, and potential prognostic value of versican (VCAN) in HCC. We conducted cell experiments such as Transwell migration and invasion assays, wound healing assay, and CCK8 experiment to explore the function of VCAN in HCC.

Result: We selected three HCC transcriptome databases GSE124535, GSE136247, and GSE144269 and analyzed the overexpressed genes contained in them. The overlapping genes were found by the Venn map, and two interacting network modules were found by Mcode. Module 1 was mainly related to mitosis and cell cycle, and module 2 was mainly related to EMT, angiogenesis, glycolysis, and so on. We found that the seed gene in module 2 is VCAN. Data from TCGAportal showed that compared with normal tissues, the expression of VCAN was up-regulated in HCC tissues. The patients with high expression of VCAN had shorter distant recurrence-free survival and overall survival. Multiple possible VCAN interactions had also been identified. These results revealed that the level of VCAN was higher in the subtypes of HCC with higher malignant degree and was connected to the poor prognosis. In addition, the treatment of VCAN with DNA methyltransferase inhibitors and transcription factor inhibitors may improve the prognosis of patients with HCC.

Conclusion: Our findings systematically elucidated the expression profile and different prognostic values of VCAN in HCC, which may provide new therapeutic targets and potential prognostic biomarkers for HCC patients.

Aggrecan and versican: two brothers close or apart

Aggrecan (Acan) and versican (Vcan) are large chondroitin sulfate proteoglycans of the extracellular matrix. They share the same structural domains at both N and C-termini. The N-terminal G1 domain binds hyaluronan (HA), forms an HA-rich matrix, and regulates HA-mediated signaling. The C-terminal G3 domain binds other extracellular matrix molecules and forms a supramolecular structure that stores TGFb and BMPs and regulates their signaling. EGF-like motifs in the G3 domain may directly act like an EGF ligand. Both Acan and Vcan are present in cartilage, intervertebral disc, brain, heart, and aorta. Their localizations are essentially reciprocal. This review describes their structural domains, expression patterns and functions, and regulation of their expression.

Cancer associated-fibroblast-derived exosomes in cancer progression

To identify novel cancer therapies, the tumor microenvironment (TME) has received a lot of attention in recent years in particular with the advent of clinical successes achieved by targeting immune checkpoint inhibitors (ICIs). The TME consists of multiple cell types that are embedded in the extracellular matrix (ECM), including immune cells, endothelial cells and cancer associated fibroblasts (CAFs), which communicate with cancer cells and each other during tumor progression. CAFs are a dominant and heterogeneous cell type within the TME with a pivotal role in controlling cancer cell invasion and metastasis, immune evasion, angiogenesis and chemotherapy resistance. CAFs mediate their effects in part by remodeling the ECM and by secreting soluble factors and extracellular vesicles. Exosomes are a subtype of extracellular vesicles (EVs), which contain various biomolecules such as nucleic acids, lipids, and proteins. The biomolecules in exosomes can be transmitted from one to another cell, and thereby affect the behavior of the receiving cell. As exosomes are also present in circulation, their contents can also be explored as biomarkers for the diagnosis and prognosis of cancer patients. In this review, we concentrate on the role of CAFs-derived exosomes in the communication between CAFs and cancer cells and other cells of the TME. First, we introduce the multiple roles of CAFs in tumorigenesis. Thereafter, we discuss the ways CAFs communicate with cancer cells and interplay with other cells of the TME, and focus in particular on the role of exosomes. Then, we elaborate on the mechanisms by which CAFs-derived exosomes contribute to cancer progression, as well as and the clinical impact of exosomes. We conclude by discussing aspects of exosomes that deserve further investigation, including emerging insights into making treatment with immune checkpoint inhibitor blockade more efficient.

[A new therapeutic target for patent ductus arteriosus]

The ductus arteriosus (DA) maintains the fetal circulation by connecting the aorta and pulmonary arteries. Patent ductus arteriosus (PDA) occurs in >70% extremely-low-birth-weight infants. Patients with PDA exhibit circulatory failure, which is caused by left-to-right shunt. The DA immediately contracts after birth in response to the elevation of blood oxygen tension and to the decline in circulating prostaglandin E₂ (PGE₂). Cyclooxygenase inhibitors targeting smooth muscle cell (SMC) contraction represent only pharmacological treatment for PDA. However, it is important for DA anatomical closure that intimal thickening (IT) is appropriately formed between SMC layer and endothelial cells (EC). IT begins to form before the second-trimester and becomes prominent toward the end of third-trimester as an increase in placenta-derived PGE₂. Immature DAs frequently fail to be close due to poorly formed IT. IT consists of extracellular matrices (ECM) and migrated DA-SMCs from the tunica media. A glycoprotein fibulin-1 is expressed in developing cardiovascular system and binds to multiple ECMs. We found that PGE₂ increased fibulin-1 via EP4 in DA-SMCs, and Fbln1-deficient mice exhibited PDA with poor IT formation. Although EP4 is a Gs-coupled GPCR, fibulin-1 was secreted from DA-SMCs through the phospholipase C-protein kinase C-non-canonical NFκB signaling pathway. Fibulin-1 bound to DA-EC-derived versican which is a binding partner of hyaluronan, which promoted directional DA-SMC migration toward ECs and contributed to IT formation in the DA. Fibulin-1 upregulation by the activation of specific downstream pathway of EP4 may serve a new pharmacological strategy for PDA.

Identification of novel ADAMTS1, ADAMTS4 and ADAMTS5 cleavage sites in versican using a label-free quantitative proteomics approach

The chondroitin sulfate proteoglycan versican is important for embryonic development and several human disorders. The versican V1 splice isoform is widely expressed and cleaved by ADAMTS proteases at a well-characterized site, Glu441-Ala442. Since ADAMTS proteases cleave the homologous proteoglycan aggrecan at multiple sites, we hypothesized that additional cleavage sites existed within versican. We report a quantitative label-free approach that ranks abundance of liquid chromatography-tandem mass spectrometry (LC-MS/MS)-identified semi-tryptic peptides after versican digestion by ADAMTS1, ADAMTS4 and ADAMTS5 to identify site-specific cleavages. Recombinant purified versican V1 constructs were digested with the recombinant full-length proteases, using catalytically inactive mutant proteases in control digests. Semi-tryptic peptide abundance ratios determined by LC-MS/MS in ADAMTS:control digests were compared to the mean of all identified peptides to obtain a z-score by which outlier peptides were ranked, using semi-tryptic peptides identifying Glu441 -Ala442 cleavage as the benchmark. Tryptic peptides with higher abundance in control digests supported cleavage site identification. We identified several novel cleavage sites supporting the ADAMTS1/4/5 cleavage site preference for a P1-Glu residue in proteoglycan substrates. Digestion of proteins in vitro and application of this z-score approach is potentially widely applicable for mapping protease cleavage sites using label-free proteomics. SIGNIFICANCE: Versican abundance and turnover are relevant to the pathogenesis of several human disorders. Versican is cleaved by A Disintegrin-like And Metalloprotease with Thrombospondin type 1 motifs (ADAMTS) family members at Glu441-Ala442, generating a bioactive proteoform called versikine, but additional cleavage sites and the site-specificity of individual ADAMTS proteases is unexplored. Here, we used a label-free proteomics strategy to identify versican cleavage sites for 3 ADAMTS proteases, applying a novel z-score-based statistical approach to compare the protease digests of versican to controls (digests with inactive protease) using the known protease cleavage site as a benchmark. We identified 21 novel cleavage sites that had a comparable z-score to the benchmark. Given the functional significance of versikine, they represent potentially significant cleavages and helped to refine a substrate site preference for each protease.The z-score approach is potentially widely applicable for discovery of site-specific cleavages within an purified protein or small ensemble of proteins using any protease.

Targeting Versican as a Potential Immunotherapeutic Strategy in the Treatment of Cancer

A growing body of literature links events associated with the progression and severity of immunity and inflammatory disease with the composition of the tissue extracellular matrix as defined by the matrisome. One protein in the matrisome that is common to many inflammatory diseases is the large proteoglycan versican, whose varied function is achieved through multiple isoforms and post-translational modifications of glycosaminoglycan structures. In cancer, increased levels of versican are associated with immune cell phenotype, disease prognosis and failure to respond to treatment. Whether these associations between versican expression and tumour immunity are the result of a direct role in the pathogenesis of tumours is not clear. In this review, we have focused on the role of versican in the immune response as it relates to tumour progression, with the aim of determining whether our current understanding of the immunobiology of versican warrants further study as a cancer immunotherapy target.

Context-dependent bioactivity of versican fragments

Versican (VCAN) proteolysis and the accumulation of VCAN fragments occur in many developmental and disease processes, affecting extracellular matrix (ECM) structure and cell phenotype. Little is known about the significance of proteolysis and the roles of fragments, or how this ECM remodeling affects the microenvironment and phenotype of diseased cells. G1-DPEAAE fragments promote aspects of epithelial-mesenchymal transitioning in developing and diseased cells, resulting in cell migration. Enhanced proliferation and invasion of tumor and endothelial cells is directly associated with G1 domain deposition and G1-DPEAAE localization respectively. These tumorigenic and angiogenic roles could explain the disease exacerbating effect often associated with G1-containing fragments, however, the pathogenicity of G1 fragments depends entirely upon the context. Overall, VCAN fragments promote tumorigenesis and inflammation; however, the specific cleavage site, the extent of cleavage activity and the microenvironment in which cleavage occurs collectively determine how this pleiotropic molecule and its fragments influence cells.

Versican contributes to ligament formation of knee joints

Versican is a large proteoglycan in the extracellular matrix. During embryonic stages, it plays a crucial role in the development of cartilage, heart, and dermis. Previously, we reported that Prx1-Vcan conditional knockout mice, lacking Vcan expression in mesenchymal condensation areas of the limb bud, show the impaired joint formation and delayed cartilage development. Here, we investigated their phenotype in adults and found that they develop swelling of the knee joint. Histologically, their newborn joint exhibited impaired formation of both anterior and posterior cruciate ligaments. Immunostaining revealed a decrease in scleraxis-positive cells in both articular cartilage and ligament of Prx1-Vcan knee joint, spotty patterns of type I collagen, and the presence of type II collagen concomitant with the absence of versican expression. These results suggest that versican expression during the perinatal period is required for cruciate ligaments’ formation and that its depletion affects joint function in later ages.

ADAMTS proteases and the tumor immune microenvironment: Lessons from substrates and pathologies

The relationship of ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) proteases with inflammatory processes was anticipated since their discovery. Although knowledge of these extracellular proteases in different contexts continues to grow, many questions remain unanswered. In this review, we summarize the most important studies of ADAMTSs and their substrates in inflammation and in the immune system of non-oncological disorders. In addition, we update the findings on cancer and highlight their emerging role in the tumor immune microenvironment. Although the overall functions of extracellular molecules are known to be modulated by proteolysis, specific activities attributed to intact proteins and cleaved fragments in the context of inflammation are still subject to debate. A better understanding of ADAMTS activities will help to elucidate their contribution to the immune phenotype and to open up new therapeutic and diagnostic possibilities.

Versican and Versican-matrikines in Cancer Progression, Inflammation, and Immunity

Versican is an extracellular matrix proteoglycan with key roles in multiple facets of cancer development, ranging from proliferative signaling, evasion of growth-suppressor pathways, regulation of cell death, promotion of neoangiogenesis, and tissue invasion and metastasis. Multiple lines of evidence implicate versican and its bioactive proteolytic fragments (matrikines) in the regulation of cancer inflammation and antitumor immune responses. The understanding of the dynamics of versican deposition/accumulation and its proteolytic turnover holds potential for the development of novel immune biomarkers as well as approaches to reset the immune thermostat of tumors, thus promoting efficacy of modern immunotherapies. This article summarizes work from several laboratories, including ours, on the role of this central matrix proteoglycan in tumor progression as well as tumor-immune cell cross-talk.

Engineering the Extracellular Matrix to Model the Evolving Tumor Microenvironment

Clinical evidence supports a role for the extracellular matrix (ECM) in cancer risk and prognosis across multiple tumor types, and numerous studies have demonstrated that individual ECM components impact key hallmarks of tumor progression (e.g., proliferation, migration, angiogenesis). However, the ECM is a complex network of fibrillar proteins, glycoproteins, and proteoglycans that undergoes dramatic changes in composition and organization during tumor development. In this review, we will highlight how engineering approaches can be used to examine the impact of changes in tissue architecture, ECM composition (i.e., identity and levels of individual ECM components), and cellular- and tissue-level mechanics on tumor progression. In addition, we will discuss recently developed methods to model the ECM that have not yet been applied to the study of cancer.

The Roles of Frequently Mutated Genes of Pancreatic Cancer in Regulation of Tumor Microenvironment

Pancreatic ductal adenocarcinoma has extremely high malignancy and patients with pancreatic ductal adenocarcinoma have dismal prognosis. The failure of pancreatic ductal adenocarcinoma treatment is largely due to the tumor microenvironment, which is featured by ample stromal cells and complicated extracellular matrix. Recent genomic analysis revealed that pancreatic ductal adenocarcinoma harbors frequently mutated genes including KRAS, TP53, CDKN2A, and SMAD4, which can widely alter cellular processes and behaviors. As shown by accumulating studies, these mutant genes may also change tumor microenvironment, which in turn affects pancreatic ductal adenocarcinoma progression. In this review, we summarize the role of such genetic mutations in tumor microenvironment regulation and potential mechanisms.

Versican: A Dynamic Regulator of the Extracellular Matrix

Versican is a large chondroitin sulfate/dermatan sulfate proteoglycan belonging to the aggrecan/lectican family. In adults, this proteoglycan serves as a structural macromolecule of the extracellular matrix in the brain and large blood vessels. In contrast, versican is transiently expressed at high levels during development and under pathological conditions when the extracellular matrix dramatically changes, including in the inflammation and repair process. There are many reports showing the upregulation of versican in cancer, which correlates with cancer aggressiveness. Versican has four classical splice variants, and all the variants contain G1 and G3 domains at N- and C-termini, respectively. There are two glycosaminoglycan attachment domains CSα and CSβ. The largest V0 variant contains both CSα and CSβ, V1 contains CSβ, V2 contains CSα, and the shortest G3 variant has neither of them. Versican degradation is initiated by cleavage at a site in the CSβ domain by ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) proteinases. The N-terminal fragment containing the G1 domain has been reported to exert various biological functions, although its mechanisms of action have not yet been elucidated. In this review, we describe the role of versican in inflammation and cancer and also address the biological function of versikine.

Fibulin-1 Integrates Subendothelial Extracellular Matrices and Contributes to Anatomical Closure of the Ductus Arteriosus

OBJECTIVE

The ductus arteriosus (DA) is a fetal artery connecting the aorta and pulmonary arteries. Progressive matrix remodeling, that is, intimal thickening (IT), occurs in the subendothelial region of DA to bring anatomic DA closure. IT is comprised of multiple ECMs (extracellular matrices) and migrated smooth muscle cells (SMCs). Because glycoprotein fibulin-1 binds to multiple ECMs and regulates morphogenesis during development, we investigated the role of fibulin-1 in DA closure. Approach and Results: Fibulin-1-deficient (Fbln1^-/-) mice exhibited patent DA with hypoplastic IT. An unbiased transcriptome analysis revealed that EP4 (prostaglandin E receptor 4) stimulation markedly increased fibulin-1 in DA-SMCs via phospholipase C-NFκB (nuclear factor κB) signaling pathways. Fluorescence-activated cell sorting (FACS) analysis demonstrated that fibulin-1 binding protein versican was derived from DA-endothelial cells (ECs). We examined the effect of fibulin-1 on directional migration toward ECs in association with versican by using cocultured DA-SMCs and ECs. EP4 stimulation promoted directional DA-SMC migration toward ECs, which was attenuated by either silencing fibulin-1 or versican. Immunofluorescence demonstrated that fibulin-1 and versican V0/V1 were coexpressed at the IT of wild-type DA, whereas 30% of versican-deleted mice lacking a hyaluronan binding site displayed patent DA. Fibulin-1 expression was attenuated in the EP4-deficient mouse (Ptger4^-/-) DA, which exhibits patent DA with hypoplastic IT, and fibulin-1 protein administration restored IT formation. In human DA, fibulin-1 and versican were abundantly expressed in SMCs and ECs, respectively.

CONCLUSIONS

Fibulin-1 contributes to DA closure by forming an environment favoring directional SMC migration toward the subendothelial region, at least, in part, in combination with EC-derived versican and its binding partner hyaluronan.

The synthesis and secretion of versican isoform V3 by mammalian cells: A role for N-linked glycosylation

Versican is a large extracellular matrix (ECM) chondroitin sulfate (CS) proteoglycan found in most soft tissues, which is encoded by the VCAN gene. At least four major isoforms (V0, V1, V2, and V3) are generated via alternative splicing. The isoforms of versican are expressed and accumulate in various tissues during development and disease, where they contribute to ECM structure, cell growth and migration, and immune regulation, among their many functions. While several studies have identified the mRNA transcript for the V3 isoform in a number of tissues, little is known about the synthesis, secretion, and targeting of the V3 protein. In this study, we used lentiviral generation of doxycycline-inducible rat V3 with a C-terminal tag in stable NIH 3T3 cell lines and demonstrated that V3 is processed through the classical secretory pathway. We further show that N-linked glycosylation is required for efficient secretion and solubility of the protein. By site-directed mutagenesis, we identified amino acids 57 and 330 as the active N-linked glycosylation sites on V3 when expressed in this cell type. Furthermore, exon deletion constructs of V3 revealed that exons 11-13, which code for portions of the carboxy region of the protein (G3 domain), are essential for V3 processing and secretion. Once secreted, the V3 protein associates with hyaluronan along the cell surface and within the surrounding ECM. These results establish critical parameters for the processing, solubility, and targeting of the V3 isoform by mammalian cells and establishes a role for V3 in the organization of hyaluronan.

Danger matrix molecules orchestrate CD14/CD44 signaling in cancer development

The tumor matrix together with inflammation and autophagy are crucial regulators of cancer development. Embedded in the tumor stroma are numerous proteoglycans which, in their soluble form, act as danger-associated molecular patterns (DAMPs). By interacting with innate immune receptors, the Toll-like receptors (TLRs), DAMPs autonomously trigger aseptic inflammation and can regulate autophagy. Biglycan, a known danger proteoglycan, can regulate the cross-talk between inflammation and autophagy by evoking a switch between pro-inflammatory CD14 and pro-autophagic CD44 co-receptors for TLRs. Thus, these novel mechanistic insights provide some explanation for the plethora of reports indicating that the same matrix-derived DAMP acts either as a promoter or suppressor of tumor growth. In this review we will summarize and critically discuss the role of the matrix-derived DAMPs biglycan, hyaluronan, and versican in regulating the TLR-, CD14- and CD44-signaling dialogue between inflammation and autophagy with particular emphasis on cancer development.

Versican-A Critical Extracellular Matrix Regulator of Immunity and Inflammation

The extracellular matrix (ECM) proteoglycan, versican increases along with other ECM versican binding molecules such as hyaluronan, tumor necrosis factor stimulated gene-6 (TSG-6), and inter alpha trypsin inhibitor (IαI) during inflammation in a number of different diseases such as cardiovascular and lung disease, autoimmune diseases, and several different cancers. These interactions form stable scaffolds which can act as "landing strips" for inflammatory cells as they invade tissue from the circulation. The increase in versican is often coincident with the invasion of leukocytes early in the inflammatory process. Versican interacts with inflammatory cells either indirectly via hyaluronan or directly via receptors such as CD44, P-selectin glycoprotein ligand-1 (PSGL-1), and toll-like receptors (TLRs) present on the surface of immune and non-immune cells. These interactions activate signaling pathways that promote the synthesis and secretion of inflammatory cytokines such as TNFα, IL-6, and NFκB. Versican also influences inflammation by interacting with a variety of growth factors and cytokines involved in regulating inflammation thereby influencing their bioavailability and bioactivity. Versican is produced by multiple cell types involved in the inflammatory process. Conditional total knockout of versican in a mouse model of lung inflammation demonstrated significant reduction in leukocyte invasion into the lung and reduced inflammatory cytokine expression. While versican produced by stromal cells tends to be pro-inflammatory, versican expressed by myeloid cells can create anti-inflammatory and immunosuppressive microenvironments. Inflammation in the tumor microenvironment often contains elevated levels of versican. Perturbing the accumulation of versican in tumors can inhibit inflammation and tumor progression in some cancers. Thus versican, as a component of the ECM impacts immunity and inflammation through regulating immune cell trafficking and activation. Versican is emerging as a potential target in the control of inflammation in a number of different diseases.

Accumulation of versican facilitates wound healing: Implication of its initial ADAMTS-cleavage site

Versican is a large chondroitin sulfate/dermatan sulfate proteoglycan in the extracellular matrix, and is expressed at high levels in tissues during development and remodeling in pathological conditions. Its core protein is cleaved at a region close to the N-terminal end of CSβ domain by several members of a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS) family, i.e., ADAMTS-1, 4, 5, 9, 15, and 20. Here, using a CRISPR/Cas9 system, we generated knock-in mice (V1R), which express an ADAMTS cleavage-resistant versican. Some V1R homozygote mice, termed R/R, exhibit syndactyly and organ hemorrhage. In wound healing experiments, R/R wound shows accumulation of versican and activated TGFβ-signaling in the early stage, leading to faster healing than wild type wound. Immunostaining for Ki67, CD31, smooth muscle α-actin, periostin demonstrates higher levels of overall cell proliferation and an increased number of endothelial cells and myofibroblasts. Immunostaining for CD11b and qRT-PCR for macrophage markers revealed increased levels of inflammatory cell infiltration, especially those of M1 macrophages. Cultured R/R dermal fibroblasts revealed increased deposition of versican, type I and III collagens, and hyaluronan, and upregulation of Smad2/3 signaling. Taken together, these results demonstrate that the cleavage site determines versican turnover and that versican plays a central role in the provisional matrix during the wound repair.

VersicanV1 promotes proliferation and metastasis of hepatocellular carcinoma through the activation of EGFR-PI3K-AKT pathway

Versican has been reported to participate in carcinogenesis in several malignant tumors. However, the accurate role of VersicanV1, a predominant isoform of Versican in liver, remains an enigma in hepatocellular carcinoma (HCC). The expression of VersicanV1 in HCC tissues and adjacent tissues was detected by Reverse Transcription-Polymerase Chain Reaction (RT-PCR), Western Blot (WB) and inmumohistochemistry (IHC). Gain and loss of function assays were performed to examine the role of VersicanV1 in proliferation and metastasis of HCC. Measurement of oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) in vitro and PET-CT (positron emission tomography/computed tomography) analysis in vivo were applied to evaluate the effects of VersicanV1 on glycolysis. RNA sequencing, Co-IP (Co-immunoprecipitation) and MS (mass spectrometry) were utilized to investigate the molecular mechanisms. Our current study reveals that VersicanV1, regulated by direct interaction with Linc01225, is significantly upregulated in HCC tissues and correlates with poor prognosis. Both in vitro and in vivo experiments show that knockdown of VersicanV1 in HCC cells attenuates cancer cells malignancy. Further studies identify the positive role of VersicanV1 in aerobic glycolysis. Mechanistic investigation discovers the activation of EGFR-PI3K-AKT pathway in HCC cells expressing high VersicanV1. Moreover, EGF-like motif is indispensable for VersicanV1 to promote Warburg effect of HCC cells and subsequently, proliferation, invasion, and metastasis ability via activation of EGFR-PI3K-AKT axis. In sum, our research highlights a novel role of VersicanV1 in the progression of HCC, suggesting that VersicanV1 is an indicator for prognosis and a potential therapeutic target of HCC.

ADAMTS1 protease is required for a balanced immune cell repertoire and tumour inflammatory response

Recent advances have emphasized the relevance of studying the extracellular microenvironment given its main contribution to tissue homeostasis and disease. Within this complex scenario, we have studied the extracellular protease ADAMTS1 (a disintegrin and metalloprotease with thrombospondin motif 1), implicated in vascularization and development, with reported anti- and pro-tumorigenic activities. In this work we performed a detailed study of the vasculature and substrates in adult organs of wild type and Adamts1-deficient mice. In addition to the expected alterations of organs like kidney, heart and aorta, we found that the lack of ADAMTS1 differently affects lymphocyte and myeloid populations in the spleen and bone marrow. The study of the substrate versican also revealed its alteration in the absence of the protease. With such premises, we challenged our mice with subcutaneous B16F1 syngeneic tumours and closely evaluated the immune repertoire in the tumours but also in the distant spleen and bone marrow. Our results confirmed a pro-inflammatory landscape in the absence of ADAMTS1, correlating with tumour blockade, supporting its novel role as a modulator of the immune cell response.

Versican A-subdomain is required for its adequate function in dermal development

Versican, a large chondroitin sulfate (CS) proteoglycan, serves as a structural macromolecule of the extracellular matrix (ECM) and regulates cell behavior. We determined the function of versican in dermal development using Vcan^Δ3/Δ3 mutant mice expressing versican with deleted A-subdomain of the N-terminal G1 domain. The mutant versican showed a decreased hyaluronan (HA)-binding ability and failed to accumulate in the ECM. In the early developmental stage, Vcan^Δ3/Δ3 dermis showed a decrease in versican expression as compared with WT. As development proceeded, versican expression further decreased to a barely detectable level, and Vcan^Δ3/Δ3 mice died at the neonatal period (P0). At P0, Vcan^Δ3/Δ3 dermis exhibited an impaired ECM structure and decreased cell density. While the level of collagen deposition was similar in both genotypes, collagen biosynthesis significantly decreased in Vcan^Δ3/Δ3 fibroblasts as compared with that in wild type (WT). Transforming growth factor β (TGFβ) signaling mediated through the Smad2/3-dependent pathway was down-regulated in Vcan^Δ3/Δ3 fibroblasts and a reduced TGFβ storage in the ECM was observed. Microarray analysis revealed a decrease in the expression levels of transcription factors, early growth response (Egr) 2 and 4, which act downstream of TGFβ signaling. Thus, our results suggest that A-subdomain is necessary for adequate versican expression in dermis and that versican is involved in the formation of the ECM and regulation of TGFβ signaling.

Stromal Versican Regulates Tumor Growth by Promoting Angiogenesis

The proteoglycan versican is implicated in growth and metastases of several cancers. Here we investigated a potential contribution of stromal versican to tumor growth and angiogenesis. We initially determined versican expression by several cancer cell lines. Among these, MDA-MB231 and B16F10 had none to minimal expression in contrast to Lewis lung carcinoma (LLC). Notably, tumors arising from these cell lines had higher versican levels than the cell lines themselves suggesting a contribution from the host-derived tumor stroma. In LLC-derived tumors, both the tumor and stroma expressed versican at high levels. Thus, tumor stroma can make a significant contribution to tumor versican content. Versican localized preferentially to the vicinity of tumor vasculature and macrophages in the tumor. However, an ADAMTS protease-generated versican fragment uniquely localized to vascular endothelium. To specifically determine the impact of host/stroma-derived versican we therefore compared growth of tumors from B16F10 cells, which produced littleversican, in Vcan ^hdf/+ mice and wild-type littermates. Tumors in Vcan ^hdf/+ mice had reduced growth with a lower capillary density and accumulation of capillaries at the tumor periphery. These findings illustrate the variability of tumor cell line expression of versican, and demonstrate that versican is consistently contributed by the stromal tissue, where it contributes to tumor angiogenesis.

Proteoglycans remodeling in cancer: Underlying molecular mechanisms

Extracellular matrix is a highly dynamic macromolecular network. Proteoglycans are major components of extracellular matrix playing key roles in its structural organization and cell signaling contributing to the control of numerous normal and pathological processes. As multifunctional molecules, proteoglycans participate in various cell functions during morphogenesis, wound healing, inflammation and tumorigenesis. Their interactions with matrix effectors, cell surface receptors and enzymes enable them with unique properties. In malignancy, extensive remodeling of tumor stroma is associated with marked alterations in proteoglycans' expression and structural variability. Proteoglycans exert diverse functions in tumor stroma in a cell-specific and context-specific manner and they mainly contribute to the formation of a permissive provisional matrix for tumor growth affecting tissue organization, cell-cell and cell-matrix interactions and tumor cell signaling. Proteoglycans also modulate cancer cell phenotype and properties, the development of drug resistance and tumor stroma angiogenesis. This review summarizes the proteoglycans remodeling and their novel biological roles in malignancies with particular emphasis to the underlying molecular mechanisms.

Versican Promotes Tumor Progression, Metastasis and Predicts Poor Prognosis in Renal Carcinoma

The proteoglycan versican (VCAN) promotes tumor progression and enhances metastasis in several cancers; however, its role in clear cell renal cell carcinoma (ccRCC) remains unknown. Recent evidence suggests that VCAN is an important target of chromosomal 5q gain, one of the most prevalent genetic abnormalities in ccRCC. Thus, we investigated whether VCAN expression is associated with the pathogenesis of ccRCC. VCAN expression was analyzed using three RCC and normal kidney cell lines as well as a clinical cohort of 84 matched ccRCC and normal renal tissues. Functional analyses on growth and progression properties were performed using VCAN-depleted ccRCC cells. Microarray expression profiling was employed to investigate the target genes and biologic pathways involved in VCAN-mediated ccRCC carcinogenesis. ccRCC had elevated VCAN expression in comparison with normal kidney in both cell lines and clinical specimens. The elevated expression of VCAN was significantly correlated with metastasis (P < 0.001) and worse 5-year overall survival after radical nephrectomy (P = 0.014). In vitro, VCAN knockdown significantly decreased cell proliferation and increased apoptosis in Caki-2 and 786-O cells, and this was associated with alteration of several TNF signaling-related genes such as TNFα, BID, and BAK Furthermore, VCAN depletion markedly decreased cell migration and invasion which correlated with reduction of MMP7 and CXCR4. These results demonstrate that VCAN promotes ccRCC tumorigenesis and metastasis and thus is an attractive target for novel diagnostic, prognostic, and therapeutic strategies.Implications: This study highlights the oncogenic role of VCAN in renal cell carcinogenesis and suggests that this gene has therapeutic and/or biomarker potential for renal cell cancer. Mol Cancer Res; 15(7); 884-95. ©2017 AACR.

Versican Deficiency Significantly Reduces Lung Inflammatory Response Induced by Polyinosine-Polycytidylic Acid Stimulation

Viral infection is an exacerbating factor contributing to chronic airway diseases, such as asthma, via mechanisms that are still unclear. Polyinosine-polycytidylic acid (poly(I:C)), a Toll-like receptor 3 (TLR3) agonist used as a mimetic to study viral infection, has been shown to elicit inflammatory responses in lungs and to exacerbate pulmonary allergic reactions in animal models. Previously, we have shown that poly(I:C) stimulates lung fibroblasts to accumulate an extracellular matrix (ECM), enriched in hyaluronan (HA) and its binding partner versican, which promotes monocyte adhesion. In the current study, we aimed to determine the in vivo role of versican in mediating inflammatory responses in poly(I:C)-induced lung inflammation using a tamoxifen-inducible versican-deficient mouse model (Vcan^-/- mice). In C57Bl/6 mice, poly(I:C) instillation significantly increased accumulation of versican and HA, especially in the perivascular and peribronchial regions, which were enriched in infiltrating leukocytes. In contrast, versican-deficient (Vcan^-/-) lungs did not exhibit increases in versican or HA in these regions and had strikingly reduced numbers of leukocytes in the bronchoalveolar lavage fluid and lower expression of inflammatory chemokines and cytokines. Poly(I:C) stimulation of lung fibroblasts isolated from control mice generated HA-enriched cable structures in the ECM, providing a substrate for monocytic cells in vitro, whereas lung fibroblasts from Vcan^-/- mice did not. Moreover, increases in proinflammatory cytokine expression were also greatly attenuated in the Vcan^-/- lung fibroblasts. These findings provide strong evidence that versican is a critical inflammatory mediator during poly(I:C)-induced acute lung injury and, in association with HA, generates an ECM that promotes leukocyte infiltration and adhesion.