Tumor-derived mural-like cells coordinate with endothelial cells: role of YKL-40 in mural cell-mediated angiogenesis

Vascular Immune Evasion of Mesenchymal Glioblastoma Is Mediated by Interaction and Regulation of VE-Cadherin on PD-L1

The mesenchymal subtype of glioblastoma (mGBM), which is characterized by rigorous vasculature, resists anti-tumor immune therapy. Here, we investigated the mechanistic link between tumor vascularization and the evasion of immune surveillance. Clinical datasets with GBM transcripts showed that the expression of the mesenchymal markers YKL-40 (CHI3L1) and Vimentin is correlated with elevated expression of PD-L1 and poor disease survival. Interestingly, the expression of PD-L1 was predominantly found in vascular endothelial cells. Orthotopic transplantation of glioma cells GL261 over-expressing YKL-40 in mice showed increased angiogenesis and decreased CD8+ T cell infiltration, resulting in a reduction in mouse survival. The exposure of recombinant YKL-40 protein induced PD-L1 and VE-cadherin (VE-cad) expression in endothelial cells and drove VE-cad-mediated nuclear translocation of β-catenin/LEF, where LEF upregulated PD-L1 expression. YKL-40 stimulated the dissociation of VE-cad from PD-L1, rendering PD-L1 available to interact with PD-1 from CD8+-positive TALL-104 lymphocytes and inhibit TALL-104 cytotoxicity. YKL-40 promoted TALL-104 cell migration and adhesion to endothelial cells via CCR5-dependent chemotaxis but blocked its anti-vascular immunity. Knockdown of VE-cad or the PD-L1 gene ablated the effects of YKL-40 and reinvigorated TALL-104 cell immunity against vessels. In summary, our study demonstrates a novel vascular immune escape mechanism by which mGBM promotes tumor vascularization and malignant transformation.

In Vitro Tube Formation Assays in Matrigel

Vasculature development is a combination of complex processes that require precise coordination of multiple cell types, through time and space, to generate functional blood-carrying vessels. Moreover, vasculature development can be altered when normal physiological conditions are disrupted, such as in cancer, and means to study blood vessels are of great importance. While the gold standard to explore these processes is the use of in vivo animal models, they are costly and time-consuming, and it is often difficult to dissect the molecular mechanisms involved. Thus, there are several ways to deconstruct vasculature development in vitro, in order to produce tunable systems that lead to a better understanding of cellular and molecular communication between different cell types involved, such as endothelial cells and supporting mesenchymal cells. In this method chapter, we will go into detail for one of the most popular ways of studying vasculature development in the context of cancer, which is the application of Matrigel to study tube formation of various cell types involved with vasculature development. We will provide step-by-step instructions to perform mono- and co-cultures of the major cells involved with the production of vasculature, how the results of these assays can be interpreted, and some advice to avoid common mistakes associated with Matrigel tube formation assays.

In Vitro Models to Study Angiogenesis and Vasculature

The development of vasculature in vivo is an extremely complex process that requires temporal and spatial coordination between multiple cell types to produce an effective vessel. The formation of vasculature from preexisting blood vessels, known as angiogenesis, plays important roles in several physiological and pathological processes, including wound healing, organ development and growth, ischemia, inflammatory disorders, fibrosis, and cancer. Means to deconstruct these complicated biological systems are necessary to gain mechanistic insight into their development, function, and modulation that can be tested in in vivo models and ultimately the clinic. In this chapter, we will first review the classical in vitro techniques to study angiogenesis. Next, we will explore the exciting recent advances that rely on 3D multicellular systems to more accurately mimic vasculature development in vitro. Finally, we will discuss the applications of in vitro angiogenic methods to study related vasculature phenomena, such as vasculogenic mimicry.

HOXA-AS2 promotes type I endometrial carcinoma via miRNA-302c-3p-mediated regulation of ZFX

Background

HOXA cluster antisense RNA2 (HOXA-AS2), a long-chain non-coding RNA, plays an important role in the behavior of various malignant tumors. The roles of HOXA-AS2 in endometrial cancer remain unclear.

Methods

We test expression levels of HOXA-AS2, miRNA-302c-3p, the transcription factor zinc finger X-chromosomal protein (ZFX), and the chitinase-like protein YKL-40 in endometrial carcinoma by qRT-PCR and western blotting. Luciferase reporter and qRT-PCR assays were conducted to identify potential binding sites of HOXA-AS2 to miRNA-302c-3p. Cell cycle, migration and invasion ability of endometrial cancer cells were investigated using flow-cytometric analysis, CCK-8 and transwell assays, respectively.

Results

HOXA-AS2 levels were significantly increased in endometrial cancer specimens compared to normal endometrial specimens. Upregulated HOXA-AS2 promoted invasion and proliferation of type I endometrial cancer cells. HOXA-AS2 silenced miRNA-302c-3p by binding to it. MiRNA-302c-3p negatively regulates ZFX and YKL-40. Thus HOXA-AS2 promotes the development of type I endometrial cancer via miRNA-302c-3p-mediated regulation of ZFX.

Conclusions

These findings suggest that HOXA-AS2 can act as a new therapeutic target for type I endometrial cancer.

Hypoxia induces tumor cell growth and angiogenesis in non-small cell lung carcinoma via the Akt-PDK1-HIF1α-YKL-40 pathway

BACKGROUND

As one of the most common forms of cancer, non-small cell lung carcinoma (NSCLC), is characterized by oxygen deprivation (hypoxia). The transcription factor hypoxia-inducible factor (HIF)-1α is a major mediator which responds hypoxia and regulates many contributing factors. The various modes of hypoxia regulation are frequently the focus of research studies. With reference to previous published research, we hypothesized that hypoxia promotes the growth and angiogenesis of NSCLC via the Akt-PDK1-HIF1α-YKL-40 pathway, and verified it.

METHODS

We mainly investigated changes in related factor expression between differently treated CL1-5 cells. We carried out overexpression and underexpression transfection, Western blot, rt-PCR and ELISA, and observed cellular biological behaviors by CCK-8 migration and invasion assay, and tube formation assay.

RESULTS

A hypoxic environment significantly increased the phosphorylation of Akt and PDK1 in mitochondria. The hypoxia-induced accumulation of p-Akt in mitochondria activated PDK1 phosphorylation, promoted the expression of HIF1α, and the expression of YKL-40. The overexpression of YKL-40 promoted the proliferation, migration, invasion and tubule formation of CL1-5 cells.

CONCLUSIONS

A hypoxic tumor microenvironment can promote the expansion and angiogenesis of NSCLC cells through the Akt-PDK1-HIF1α-YKL-40 pathway. This may provide a new mechanism and potential interventional target for anti-vascular lung cancer therapy.

Tumor vasculature remolding by thalidomide increases delivery and efficacy of cisplatin

Background

A promising strategy to overcome the chemoresistance is the tumor blood vessel normalization, which restores the physiological perfusion and oxygenation of tumor vasculature. Thalidomide (Thal) has been shown to increase the anti-tumor effect of chemotherapy agents in solid tumors. However, it is not yet known whether the synergistic effect of Thal combined with other cytotoxic drugs is attributable to tumor vascular normalization.

Methods

We used two homograft mice models (4 T1 breast tumor model and CT26 colorectal tumor model) to investigate the effect of Thal on tumor growth, microvessel density, vascular physiology, vascular maturity and function, drug delivery and chemosensitivity. Immunofluorescence, immunohistochemistry and scanning electron microscopy were performed to determine the vessel changes. Protein array assay, qPCR and western blotting were used to detect the molecular mechanism by which Thal regulates tumor vascular.

Results

Here we report that Thal potently suppressed tumor growth, angiogenesis, hypoxia, and vascular permeability in animal models. Thal also induced a regular monolayer of endothelial cells in tumor vessels, inhibiting vascular instability, and normalized tumor vessels by increasing vascular maturity, pericyte coverage and endothelial junctions. The tumor vessel stabilization effect of Thal resulted in a decrease in tumor vessel tortuosity and leakage, and increased vessel thickness and tumor perfusion. Eventually, the delivery of cisplatin was highly enhanced through the normalized tumor vasculature, thus resulting in profound anti-tumor and anti-metastatic effects. Mechanistically, the effects of Thal on tumor vessels were caused in part by its capability to correct the imbalance between pro-angiogenic factors and anti-angiogenic factors.

Conclusions

Our findings provide direct evidence that Thal remodels the abnormal tumor vessel system into a normalized vasculature. Our results may lay solid foundation for the development of Thal as a novel candidate agent to maximize the therapeutic efficacy of chemotherapeutic drugs for solid tumors.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1366-x) contains supplementary material, which is available to authorized users.

YKL-40 can promote angiogenesis in sporadic cerebral cavernous malformation (CCM)

The factors affecting the formation of sporadic CCMs remain unclear. A cDNA microarray was used to identify characteristic gene expression patterns in sporadic CCMs. Transcription level of YKL-40 was confirmed by reverse transcription-polymerase chain reaction (RT-PCR). The location and expression were revealed by immunochemistry, immunofluorescence staining and level of YKL-40 was quantified by Western blotting. Alterations to endothelial function following the up or down regulation of gene expression was assessed by Transwell assays, cell counting kit-8 assays and capillary-like tube formation assays in human brain microvascular endothelial cells (HBMECs) in vitro. We generated a murine model by stereotaxically injecting HBMECs with expressing amounts of YKL-40 into the brain. cDNA microarray and RT-PCR results revealed that the transcription level of YKL-40 was ≥140-fold higher in sporadic CCMs in healthy controls. Histological staining revealed excessive YKL-40 expression in the CCM endothelium. Western blotting results analysis showed that YKL-40 protein expression was significantly higher in CCM endothelium (P < 0.05). YKL-40 over-expressing HBMECs showed increased cell proliferation, migration and tube formation ability compared with the control group, whereas downregulating of YKL-40 inhibited the proliferation, migration of HBMECs and capillary-like tube formation (P < 0.05). In animals, increased of YKL-40 was associated with abnormal vascular lesions that were similar to CCMs. YKL-40 is over-expressed in the CCM endothelium and acts as an angiogenic factor that promotes the pathogenesis of sporadic CCMs. YKL-40 may therefore represent a potential therapeutic target in the treatment of sporadic CCM.

Higher Pericyte Content and Secretory Activity of Microfragmented Human Adipose Tissue Compared to Enzymatically Derived Stromal Vascular Fraction

Autologous adipose tissue is used for tissue repletion and/or regeneration as an intact lipoaspirate or as enzymatically derived stromal vascular fraction (SVF), which may be first cultured into mesenchymal stem cells (MSCs). Alternatively, transplant of autologous adipose tissue mechanically fragmented into submillimeter clusters has recently showed remarkable efficacy in diverse therapeutic indications. To document the biologic basis of the regenerative potential of microfragmented adipose tissue, we first analyzed the distribution of perivascular presumptive MSCs in adipose tissue processed with the Lipogems technology, observing a significant enrichment in pericytes, at the expense of adventitial cells, as compared to isogenic enzymatically processed lipoaspirates. The importance of MSCs as trophic and immunomodulatory cells, due to the secretion of specific factors, has been described. Therefore, we investigated protein secretion by cultured adipose tissue clusters or enzymatically derived SVF using secretome arrays. In culture, microfragmented adipose tissue releases many more growth factors and cytokines involved in tissue repair and regeneration, noticeably via angiogenesis, compared to isogenic SVF. Therefore, we suggest that the efficient tissue repair/regeneration observed after transplantation of microfragmented adipose tissue is due to the secretory ability of the intact perivascular niche. Stem Cells Translational Medicine 2018;7:876-886.

The contribution of tumor-associated macrophages in glioma neo-angiogenesis and implications for anti-angiogenic strategies

"Tumor-associated macrophages" (TAMs) form a significant cell population in malignant tumors and contribute to tumor growth, metastasis, and neovascularization. Gliomas are characterized by extensive neo-angiogenesis, and knowledge of the role of TAMs in neovascularization is important for future anti-angiogenic therapies. The phenotypes and functions of TAMs are heterogeneous and more complex than a classification into M1 and M2 inflammation response types would suggest. In this review, we provide an update on the current knowledge of the ontogeny of TAMs, focusing on diffuse gliomas. The role of TAMs in the regulation of the different processes in tumor angiogenesis is highlighted and the most recently discovered mechanisms by which TAMs mediate resistance against current antivascular therapies are mentioned. Novel compounds tested in clinical trials are discussed and brought in relation to different TAM-related angiogenesis pathways. In addition, potential therapeutic targets used to intervene in TAM-regulated tumor angiogenesis are summarized.

TrkB-containing exosomes promote the transfer of glioblastoma aggressiveness to YKL-40-inactivated glioblastoma cells

The neurotrophin receptors are known to promote growth and proliferation of glioblastoma cells. Their functions in spreading glioblastoma cell aggressiveness to the microenvironment through exosome release from glioblastoma cells are unknown. Considering previous reports demonstrating that YKL-40 expression is associated with undifferentiated glioblastoma cancer stem cells, we used YKL-40-silenced cells to modulate the U87-MG differentiated state and their biological aggressiveness. Herein, we demonstrated a relationship between neurotrophin-receptors and YKL-40 expression in undifferentiated cells. Differential functions of cells and derived-exosomes were evidenced according to neurotrophin receptor content and differentiated cell state by comparison with control pLKO cells. YKL-40 silencing of glioblastoma cells impairs proliferation, neurosphere formation, and their ability to induce endothelial cell (HBMEC) migration. The modulation of differentiated cell state in YKL-40-silenced cells induces a decrease of TrkB, sortilin and p75NTR cellular expressions, associated with a low-aggressiveness phenotype. Interestingly, TrkB expressed in exosomes derived from control cells was undetectable in exosomes from YKL-40 -silenced cells. The transfer of TrkB-containing exosomes in YKL-40-silenced cells contributed to restore cell proliferation and promote endothelial cell activation. Interestingly, in U87 MG xenografted mice, TrkB-depleted exosomes from YKL-40-silenced cells inhibited tumor growth in vivo. These data highlight that TrkB-containing exosomes play a key role in the control of glioblastoma progression and aggressiveness. Furthermore, TrkB expression was detected in exosomes isolated from plasma of glioblastoma patients, suggesting that this receptor may be considered as a new biomarker for glioblastoma diagnosis.

A Heparin Binding Motif Rich in Arginine and Lysine is the Functional Domain of YKL-40

The heparin-binding glycoprotein YKL-40 (CHI3L1) is intimately associated with microvascularization in multiple human diseases including cancer and inflammation. However, the heparin-binding domain(s) pertinent to the angiogenic activity have yet been identified. YKL-40 harbors a consensus heparin-binding motif that consists of positively charged arginine (R) and lysine (K) (RRDK; residues 144–147); but they don't bind to heparin. Intriguingly, we identified a separate KR-rich domain (residues 334–345) that does display strong heparin binding affinity. A short synthetic peptide spanning this KR-rich domain successfully competed with YKL-40 and blocked its ability to bind heparin. Three individual point mutations, where alanine (A) substituted for K or R (K337A, K342A, R344A), led to remarkable decreases in heparin-binding ability and angiogenic activity. In addition, a neutralizing anti-YKL-40 antibody that targets these residues and prevents heparin binding impeded angiogenesis in vitro. MDA-MB-231 breast cancer cells engineered to express ectopic K337A, K342A or R344A mutants displayed reduced tumor development and compromised tumor vessel formation in mice relative to control cells expressing wild-type YKL-40. These data reveal that the KR-rich heparin-binding motif is the functional heparin-binding domain of YKL-40. Our findings shed light on novel molecular mechanisms underlying endothelial cell angiogenesis promoted by YKL-40 in a variety of diseases.

Plasma YKL-40 as a biomarker for bevacizumab efficacy in patients with newly diagnosed glioblastoma in the phase 3 randomized AVAglio trial

YKL-40 is a glycoprotein with pro-angiogenic functions. We hypothesized that patients with newly diagnosed glioblastoma and low baseline plasma YKL-40 levels derive greater benefit from first-line bevacizumab. Plasma samples were collected from 563 patients in the randomized, phase 3 AVAglio trial who received bevacizumab or placebo plus radiotherapy/temozolomide. Raw plasma YKL-40 concentrations were converted to age-corrected percentiles of normal healthy YKL-40 levels and divided into quartiles (Q). The impact of baseline plasma YKL-40 level on survival was investigated using Cox regression analyses. Patients with low baseline plasma YKL-40 (≤Q1) had an improved progression-free survival hazard ratio (HR) for bevacizumab versus placebo (0.37, 95% confidence interval [CI]: 0.25–0.55) compared with high plasma YKL-40 (> Q1) (0.71, 95% CI: 0.57–0.87). Overall survival HRs were comparable between the subgroups (≤ Q1: 0.69, 95% CI: 0.44–1.09; (> Q1: 0.88, 95% CI: 0.68–1.13). A trend for improved progression-free survival HR with low versus high YKL-40 was observed in proneural glioblastoma (0.41, 95% CI: 0.13–1.28 vs 0.80, 95% CI: 0.45–1.40, respectively), but not for proliferative/mesenchymal subtypes. Elevated plasma YKL-40 (> 90th percentile of normal) was an independent negative prognostic factor. In conclusion, the predictive value of baseline plasma YKL-40 level as a biomarker for bevacizumab efficacy in glioblastoma may be limited to patients with proneural tumors. Independent validation studies are required to confirm these results.

YKL-40 promotes the migration and invasion of prostate cancer cells by regulating epithelial mesenchymal transition

OBJECTIVE

This study aims to observe the expression of YKL-40 in prostate cancer and whether YKL-40 can affect the migration and invasion of tumor cells by regulating epithelial mesenchymal transition.

METHODS

We collected 14 cases of prostate cancer tissues and adjacent tissues in this study. The expression levels of YKL-40 in the tissues were analyzed by western blotting and immunohistochemical methods. The expression of YKL-40 in human prostate cancer cell line DU145 and PC3 was detected by fluorescence quantitative PCR and western blotting methods. The expression levels of YKL-40 in different cells were up-regulated or down- regulated by lentivirus to observe the changes of cell migration and invasion. The expression levels of EMT related genes were analyzed by RT-PCR and Western blotting methods.

RESULTS

The expression level of YKL-40 in prostate cancer tissues was significantly higher than that in adjacent tissues (P<0.01), and it was higher in DU145 cells than that in PC3 cells (P<0.05). The expression level of YKL-40 was positively correlated with cell migration and invasion. YKL-40 can regulate the expression of EMT related genes (Twist, Snail, Slug, N-cadherin, Vimentin and E-cadherin).

CONCLUSIONS

The expression level of YKL-40 was positively correlated with the migration and invasion of prostate cells, it affects cancer metastasis by regulating EMT.

Inhibition of the Glycolytic Activator PFKFB3 in Endothelium Induces Tumor Vessel Normalization, Impairs Metastasis, and Improves Chemotherapy

Abnormal tumor vessels promote metastasis and impair chemotherapy. Hence, tumor vessel normalization (TVN) is emerging as an anti-cancer treatment. Here, we show that tumor endothelial cells (ECs) have a hyper-glycolytic metabolism, shunting intermediates to nucleotide synthesis. EC haplo-deficiency or blockade of the glycolytic activator PFKFB3 did not affect tumor growth, but reduced cancer cell invasion, intravasation, and metastasis by normalizing tumor vessels, which improved vessel maturation and perfusion. Mechanistically, PFKFB3 inhibition tightened the vascular barrier by reducing VE-cadherin endocytosis in ECs, and rendering pericytes more quiescent and adhesive (via upregulation of N-cadherin) through glycolysis reduction; it also lowered the expression of cancer cell adhesion molecules in ECs by decreasing NF-κB signaling. PFKFB3-blockade treatment also improved chemotherapy of primary and metastatic tumors.

Role of chitinase-like proteins in cancer

Chitinase-like proteins (CLPs) are lectins combining properties of cytokines and growth factors. Human CLPs include YKL-40, YKL-39 and SI-CLP that are secreted by cancer cells, macrophages, neutrophils, synoviocytes, chondrocytes and other cells. The best investigated CLP in cancer is YKL-40. Serum and plasma levels of YKL-40 correlate with poor prognosis in breast, lung, prostate, liver, bladder, colon and other types of cancers. In combination with other circulating factors YKL-40 can be used as a predictive biomarker of cancer outcome. In experimental models YKL-40 supports tumor initiation through binding to RAGE, and is able to induce cancer cell proliferation via ERK1/2-MAPK pathway. YKL-40 supports tumor angiogenesis by interaction with syndecan-1 on endothelial cells and metastatic spread by stimulating production of pro-inflammatory and pro-invasive factors MMP9, CCL2 and CXCL2. CLPs induce production of pro- and anti-inflammatory cytokines and chemokines, and are potential modulators of inflammatory tumor microenvironment. Targeting YKL-40 using neutralizing antibodies exerts anti-cancer effect in preclinical animal models. Multifunctional role of CLPs in regulation of inflammation and intratumoral processes makes them attractive candidates for tumor therapy and immunomodulation. In this review we comprehensively analyze recent data about expression pattern, and involvement of human CLPs in cancer.

Vascular heterogeneity and targeting: the role of YKL-40 in glioblastoma vascularization

Malignant glioblastomas (GBM) are highly malignant brain tumors that have extensive and aberrant tumor vasculature, including multiple types of vessels. This review focuses on recent discoveries that the angiogenic factor YKL-40 (CHI3L1) acts on glioblastoma-stem like cells (GSCs) to drive the formation of two major forms of tumor vascularization: angiogenesis and vasculogenic mimicry (VM). GSCs possess multipotent cells able to transdifferentiate into vascular pericytes or smooth muscle cells (PC/SMCs) that either coordinate with endothelial cells (ECs) to facilitate angiogenesis or assemble in the absence of ECs to form blood-perfused channels via VM. GBMs express high levels of YKL-40 that drives the divergent signaling cascades to mediate the formation of these distinct microvascular circulations. Although a variety of anti-tumor agents that target angiogenesis have demonstrated transient benefits for patients, they often fail to restrict tumor growth, which underscores the need for additional therapeutic tools. We propose that targeting YKL-40 may compliment conventional anti-angiogenic therapies to provide a substantial clinical benefit to patients with GBM and several other types of solid tumors.

Overexpression of CHI3L1 is associated with chemoresistance and poor outcome of epithelial ovarian carcinoma

We propose CHI3L1 as a prognostic biomarker for patients with epithelial ovarian carcinoma (EOC) and also suggest possible biological functions of CHI3L1. We measured CHI3L1 expression with quantitative real time-polymerase chain reaction (qRT-PCR) in 180 women with EOC and evaluated correlations between CHI3L1 expression, clinicopathological characteristics, and the outcomes of the patients. The expression of CHI3L1 was higher in cancerous tissues than in normal tissues. The expression of CHI3L1 was also higher in patients with a serous histological type, advanced stage, and chemoresistance. Patients with high CHI3L1 expression had a shorter progression-free survival (p < 0.001)and overall survival (p < 0.001). Patients with high CHI3L1 expression also had a high risk of recurrence (p < 0.001)and death (p < 0.001). In vitro studies showed that CHI3L1 up-regulated the expression of anti-apoptotic Mcl-1 protein and hampered paclitaxel-induced apoptosis of ovarian cancer cells. These results suggest that CHI3L1 shows potential as a prognostic biomarker for EOC. CHI3L1 may promote chemoresistance via inhibition of drug-induced apoptosis by up-regulating Mcl-1.

Mechanistic roles of epithelial and immune cell signaling during the development of colitis-associated cancer

To date, substantial evidence has shown a significant association between inflammatory bowel diseases (IBD) and development of colitis-associated cancer (CAC). The incidence/prevalence of IBD is higher in western countries including the US, Australia, and the UK. Although CAC development is generally characterized by stepwise accumulation of genetic as well as epigenetic changes, precise mechanisms of how chronic inflammation leads to the development of CAC are largely unknown. Preceding intestinal inflammation is one of the major influential factors for CAC tumorigenesis. Mucosal immune responses including activation of aberrant signaling pathways both in innate and adaptive immune cells play a pivotal role in CAC. Tumor progression and metastasis are shaped by a tightly controlled tumor microenvironment which is orchestrated by several immune cells and stromal cells including macrophages, neutrophils, dendritic cells, myeloid derived suppressor cells, T cells, and myofibroblasts. In this article, we will discuss the contributing factors of epithelial as well as immune cell signaling in initiation of CAC tumorigenesis and mucosal immune regulatory factors in the colonic tumor microenvironment. In depth understanding of these factors is necessary to develop novel anti-inflammatory and anti-cancer therapies for CAC in the near future.

A novel method for endothelial cell isolation

The present study aimed to develop a quick and efficient method for purification of newborn endothelial cells from tumor tissues. Fresh tissues were separated from C57BL/6 mice bearing tumors derived from mouse lung cancer Lewis cells, fully minced and divided into two parts. One part was subjected to collagenase type I digestion with a vortex to form a single-cell suspension, while another part was digested but without a vortex. Then, the CD105+ cells were isolated using anti-CD105 antibody-coated Dynabeads. The isolated CD105+ cells were grown in culture medium and examined for the surface expression of CD105 by a fluorescence-activated cell sorter (FACS). The uptake of acetylated LDL and the ability to maintain capillary tube-like structure formation in the CD105+ cells were also examined by Dil-Ac-LDL uptake assay and tube formation assay. The expression of tumor newborn endothelial cells (CD105+) was tested in Lewis xenografts by immunohistochemistry. The number of cells which were obtained by the digestion process with a vortex was 5.70±0.23x10(4) much higher than the number without a vortex (0.32±0.04x10(4)) (P<0.01). The purity of CD105+ cell digestion with a vortex was significantly higher than that without a vortex. Dil-Ac-LDL uptake assay and tube formation assay confirmed that the CD105+ cells digested with a vortex exhibited typical functions of endothelial cells. In conclusion, the CD105+ cells isolated by the new method had high purity and displayed features of vascular endothelial cells. The modified method provides CD105+ cells with superior conditions for mechanistic research on the development of vessel-based disease.

Circulating and Tissue Expression Levels of YKL-40 in Renal Cell Cancer

PURPOSE

Blood levels of YKL-40 are elevated in various malignancies and other inflammatory diseases. Higher YKL-40 levels have consequently been shown to correlate with poor prognosis in several cancers. We investigated the prognostic value of circulating and tissue levels of YKL-40 in renal cell cancer.

MATERIALS AND METHODS

Preoperative YKL-40 serum/plasma levels were determined in 222 surgically treated patients with renal cell cancer and in 35 controls. Postoperative serum samples were analyzed in 19 of the 222 renal cell cancer cases. Gene expression levels were assessed in 101 renal cell cancer frozen tissue samples using quantitative real-time reverse transcriptase-polymerase chain reaction. Finally immunohistochemical analysis was done in 37 renal cell cancer cases to assess tissue localization of YKL-40. Results were correlated with clinicopathological and followup data.

RESULTS

YKL-40 serum but not tissue gene expression levels were higher in patients with renal cell cancer compared to controls (p = 0.050). Serum YKL-40 levels significantly increased following nephrectomy (p <0.001). High circulating YKL-40 concentrations were independently associated with shorter survival in the serum and plasma cohorts. YKL-40 gene expression did not correlate with patient prognosis.

CONCLUSIONS

Preoperatively elevated circulating levels of YKL-40 predict survival in patients treated with nephrectomy for renal cell cancer independently of levels determined in serum or plasma. Tumor cells do not seem to be the main source of increased serum/plasma YKL-40 levels in patients with renal cell cancer.

YKL-40/CHI3L1 drives inflammation on the road of tumor progression

Inflammation plays a vital role at different stages of tumor progression. The development of tumors is affected by inflammatory mediators produced by the tumor and the host. YKL-40/chitinase-3-like-1 protein is often up-regulated in inflammation-associated diseases. With the use of chronic inflammatory disease systems, we describe the role of YKL-40/chitinase-3-like-1 protein in enhancing the inflammatory response and its implications in tumorigenesis. We also discuss how pre-existing inflammation enhances tumor growth and metastasis. In this mini-review, we highlight the effect of YKL-40/chitinase-3-like-1 protein-associated inflammation in promoting tumor progression.

Observational and genetic plasma YKL-40 and cancer in 96,099 individuals from the general population

Plasma YKL-40 is high in patients with cancer and in individuals who later develop cancer. Whether YKL-40 is only a marker or indeed a cause of cancer is presently unknown. We tested the hypothesis that observationally and genetically, high plasma YKL-40 is associated with high risk of cancer. For this purpose, we performed cohort and Mendelian randomization studies in 96,099 individuals from the Danish general population. Plasma levels of YKL-40 were measured in 21,643 and CHI3L1 rs4950928 was genotyped in 94,568 individuals. From 1943 through 2011, 2,291 individuals developed gastrointestinal cancer, 913 developed lung cancer, 2,863 women developed breast cancer, 1,557 men developed prostate cancer and 5,146 individuals developed other cancer. Follow-up was 100% complete. Multifactorially and CRP adjusted hazard ratio (HR) for gastrointestinal cancer was 1.82 (95%CI, 1.16-2.86) for 96-100% versus 0-33% YKL-40 percentile category. Corresponding HR were 1.71 (0.95-3.07) for lung cancer, but insignificant for breast cancer, prostate cancer and other cancers. CHI3L1 rs4950928 genotype was associated with plasmaYKL-40 levels, but not with risk of any cancer category. For gastrointestinal cancer, a doubling in YKL-40 was associated with a multifactorially and CRP adjusted observational HR of 1.14(1.05-1.23) for gastrointestinal cancer, but a corresponding genetic odds ratio of 1.06(0.94-1.18). For lung cancer, corresponding risk estimates were 1.11(1.00-1.22) observationally and 1.01(0.84-1.20) genetically. For other cancer categories, observational and genetic findings were insignificant. This study shows that high plasma YKL-40 levels were associated with high risk of gastrointestinal and likely of lung cancer, but genetic high levels were not.

Keeping track of the growing number of biological functions of chitin and its interaction partners in biomedical research

Chitin is a vital polysaccharide component of protective structures in many eukaryotic organisms but seems absent in vertebrates. Chitin or chitin oligomers are therefore prime candidates for non-self-molecules, which are recognized and degraded by the vertebrate immune system. Despite the absence of polymeric chitin in vertebrates, chitinases and chitinase-like proteins (CLPs) are well conserved in vertebrate species. In many studies, these proteins have been found to be involved in immune regulation and in mediating the degradation of chitinous external protective structures of invading pathogens. Several important aspects of chitin immunostimulation have recently been uncovered, advancing our understanding of the complex regulatory mechanisms that chitin mediates. Likewise, the last few years have seen large advances in our understanding of the mechanisms and molecular interactions of chitinases and CLPs in relation to immune response regulation. It is becoming increasingly clear that their function in this context is not exclusive to chitin producing pathogens, but includes bacterial infections and cancer signaling as well. Here we provide an overview of the immune signaling properties of chitin and other closely related biomolecules. We also review the latest literature on chitinases and CLPs of the GH18 family. Finally, we examine the existing literature on zebrafish chitinases, and propose the use of zebrafish as a versatile model to complement the existing murine models. This could especially be of benefit to the exploration of the function of chitinases in infectious diseases using high-throughput approaches and pharmaceutical interventions.

Epigenetic profile of human adventitial progenitor cells correlates with therapeutic outcomes in a mouse model of limb ischemia

OBJECTIVE

We investigated the association between the functional, epigenetic, and expressional profile of human adventitial progenitor cells (APCs) and therapeutic activity in a model of limb ischemia.

APPROACH AND RESULTS

Antigenic and functional features were analyzed throughout passaging in 15 saphenous vein (SV)-derived APC lines, of which 10 from SV leftovers of coronary artery bypass graft surgery and 5 from varicose SV removal. Moreover, 5 SV-APC lines were transplanted (8×10(5) cells, IM) in mice with limb ischemia. Blood flow and capillary and arteriole density were correlated with functional characteristics and DNA methylation/expressional markers of transplanted cells. We report successful expansion of tested lines, which reached the therapeutic target of 30 to 50 million cells in ≈10 weeks. Typical antigenic profile, viability, and migratory and proangiogenic activities were conserved through passaging, with low levels of replicative senescence. In vivo, SV-APC transplantation improved blood flow recovery and revascularization of ischemic limbs. Whole genome screening showed an association between DNA methylation at the promoter or gene body level and microvascular density and to a lesser extent with blood flow recovery. Expressional studies highlighted the implication of an angiogenic network centered on the vascular endothelial growth factor receptor as a predictor of microvascular outcomes. FLT-1 gene silencing in SV-APCs remarkably reduced their ability to form tubes in vitro and support tube formation by human umbilical vein endothelial cells, thus confirming the importance of this signaling in SV-APC angiogenic function.

CONCLUSIONS

DNA methylation landscape illustrates different therapeutic activities of human APCs. Epigenetic screening may help identify determinants of therapeutic vasculogenesis in ischemic disease.

Increased expression of Chitinase 3-like 1 and microvessel density predicts metastasis and poor prognosis in clear cell renal cell carcinoma

Increasing evidence demonstrated that Chitinase 3-like 1 (hereafter termed CHI3L1 or YKL-40) was highly expressed and tightly associated with human tumor development and progression. However, its precise role in clear cell renal cell carcinoma (hereafter termed RCC) remains to be delineated. In the present study, we investigated the relationship between CHI3L1 expression and microvessel density (MVD), a reflection of angiogenesis, with metastasis and prognosis in patients with clear cell renal cell carcinoma (RCC). Formalin-fixed, paraffin-embedded tissue sections of clear cell RCC from 73 patients who had undergone radical nephrectomy were stained immunohistochemically with specific antibodies against CHI3L1 and CD34. CHI3L1 immunostaining was semi-quantitatively estimated based on the proportion (percentage of positive cells) and intensity. MVD was determined with CD34-stained slides. The expression pattern of CHI3L1 and MVD was compared with the clinicopathological variables. Twenty patients had either synchronous or metachronous metastases and 12 died during the follow-up. CHI3L1 intensity was significantly correlated with tumor size (P = 0.005), TNM stage (P = 0.027), M stage (P = 0.011), grade (P = 0.014), and metastasis (synchronous or metachronous; P < 0.001). The CHI3L1 proportion (P = 0.038) and MVD (P = 0.012) were significantly correlated with metastasis. MVD was correlated with CHI3L1 intensity (r = 0.376, P = 0.001) and CHI3L1 proportion (r = 0.364, P = 0.002). There was no difference in the expression of CHI3L1 and MVD between primary and metastatic sites. The survival of patients with higher CHI3L1 intensity was significantly worse than that of patients with lower CHI3L1 intensity. Multivariate analyses indicated that only M stage was an independent prognostic factor for cancer-specific survival and CHI3L1 expression was not an independent factor. Taken altogether, increased expression of CHI3L1 and MVD is associated with metastasis and a worse prognosis in clear cell RCC. CHI3L1 expression is correlated with MVD. The results suggest that CHI3L1 may be important in the progression and angiogenesis of clear cell RCC and CHI3L1 might be a novel strategy for therapy of the patients with RCC.

Role of tumor associated macrophages in tumor angiogenesis and lymphangiogenesis

Tumor angiogenesis is an essential process for supplying rapidly growing malignant tissues with essential nutrients and oxygen. An angiogenic switch allows tumor cells to survive and grow, and provides them access to vasculature resulting in metastatic disease. Monocyte-derived macrophages recruited and reprogrammed by tumor cells serve as a major source of angiogenic factors boosting the angiogenic switch. Tumor endothelium releases angiopoietin-2 and further facilitates recruitment of TIE2 receptor expressing monocytes (TEM) into tumor sites. Tumor-associated macrophages (TAM) sense hypoxia in avascular areas of tumors, and react by production of angiogenic factors such as VEGFA. VEGFA stimulates chemotaxis of endothelial cells (EC) and macrophages. In some tumors, TAM appeared to be a major source of MMP9. Elevated expression of MMP9 by TAM mediates extracellular matrix (ECM) degradation and the release of bioactive VEGFA. Other angiogenic factors released by TAM include basic fibroblast growth factor (bFGF), thymidine phosphorylase (TP), urokinase-type plasminogen activator (uPA), and adrenomedullin (ADM). The same factors used by macrophages for the induction of angiogenesis [like vascular endothelial growth factor A (VEGF-A) and MMP9] support lymphangiogenesis. TAM can express LYVE-1, one of the established markers of lymphatic endothelium. TAM support tumor lymphangiogenesis not only by secretion of pro-lymphangiogenic factors but also by trans-differentiation into lymphatic EC. New pro-angiogenic factor YKL-40 belongs to a family of mammalian chitinase-like proteins (CLP) that act as cytokines or growth factors. Human CLP family comprises YKL-40, YKL-39, and SI-CLP. Production of all three CLP in macrophages is antagonistically regulated by cytokines. It was recently established that YKL-40 induces angiogenesis in vitro and in animal tumor models. YKL-40-neutralizing monoclonal antibody blocks tumor angiogenesis and progression. The role of YKL-39 and SI-CLP in tumor angiogenesis and lymphangiogenesis remains to be investigated.

Plasma YKL-40 in patients with metastatic colorectal cancer treated with first line oxaliplatin-based regimen with or without cetuximab: RESULTS from the NORDIC VII Study

Background

We aim to test the hypothesis that high plasma YKL-40 is associated with short progression-free survival (PFS) and overall survival (OS) in patients with metastatic colorectal cancer (mCRC) treated with first-line oxaliplatin and 5-flourouracil with or without cetuximab.

Patients and Methods

A total of 566 patients in the NORDIC VII Study were randomized 1∶1∶1 to arm A (Nordic FLOX), arm B (Nordic FLOX + cetuximab), or arm C (Nordic FLOX + cetuximab for 16 weeks followed by cetuximab alone as maintenance therapy). Pretreatment plasma samples were available from 510 patients. Plasma YKL-40 was determined by ELISA and dichotomized according to the age-corrected 95% YKL-40 level in 3130 healthy subjects.

Results

Pretreatment plasma YKL-40 was elevated in 204 patients (40%), and median YKL-40 was higher in patients with mCRC than in healthy subjects (age adjusted, P<0.001). Patients with elevated YKL-40 had shorter PFS than patients with normal YKL-40 (7.5 vs. 8.2 months; hazard ratio (HR)  = 1.27 95% confidence interval (CI) 1.05–1.53 P = 0.013) and shorter OS (16.8 vs. 23.9 months; HR = 1.33, 1.04–1.69, P = 0.024). Multivariate Cox analysis demonstrated that elevated pretreatment YKL-40 was an independent biomarker of short OS (HR = 1.12, 1.01–1.25, P = 0.033). The ratio of the updated plasma YKL-40 (i.e. level after 1, 2, 8 weeks of treatment, and at end of treatment compared to the baseline level) was associated with OS (HR = 1.27, 1.06–1.52, P = 0.011).

Conclusions

Plasma YKL-40 is an independent prognostic biomarker in patients with mCRC treated with first-line oxaliplatin-based therapy alone or combined with cetuximab.

Anti-YKL-40 antibody and ionizing irradiation synergistically inhibit tumor vascularization and malignancy in glioblastoma

Chemo/radiotherapies are the most common adjuvant modality treated for patients with glioblastoma (GBM) following surgery. However, the overall therapeutic benefits are still uncertain, as the mortality remains high. Elevated expression of YKL-40 in GBM was correlated with increases in mural cell-associated vessel coverage, stability and density, and decreases in vessel permeability and disease survival. To explore the potential role of YKL-40 in mural cell-mediated tumor vascularization, we employed an anti-YKL-40 neutralizing antibody (mAY) and ionizing irradiation (IR) in xenografted brain tumor models. Although single treatment with mAY or IR partially increased mouse survival, their combination led to dramatic inhibition in tumor growth and increases in mouse survival. mAY blocked mural cell-mediated vascular stability, integrity and angiogenesis; whereas IR merely promoted tumor cell and vascular cell apoptosis. Vascular radioresistance is at least partially attributed to expression of YKL-40 in mural cells. These divergent effects were also recapitulated in cultured systems using endothelial cells and mural cells differentiated from glioblastoma stem-like cells (GSCs). Dysfunction of intercellular contact N-cadherin was found to mediate mAY-inhibited vascularization. Collectively, the data suggest that the conjunction therapy with mAY and IR synergistically inhibit tumor vascularization and progression. The evidence may shed light on a new adjuvant therapy in clinic.

YKL-40 acts as an angiogenic factor to promote tumor angiogenesis

A secreted glycoprotein YKL-40 also named chitinase-3-like-1 is normally expressed by multiple cell types such as macrophages, chondrocytes, and vascular smooth muscle cells. However, a prominently high level of YKL-40 was found in a wide spectrum of human diseases including cancers and chronic inflammatory diseases where it was strongly expressed by cancerous cells and infiltrating macrophages. Here, we summarized recent important findings of YKL-40 derived from cancerous cells and smooth muscle cells during tumor angiogenesis and development. YKL-40 is a potent angiogenic factor capable of stimulating tumor vascularization mediated by endothelial cells and maintaining vascular integrity supported by smooth muscle cells. In addition, YKL-40 induces FAK-MAPK signaling and up-regulates VEGF receptor 2 in endothelial cells; but a neutralizing antibody (mAY) against YKL-40 inhibits its angiogenic activity. While YKL-40 is essential for angiogenesis, little is known about its functional role in tumor-associated macrophage (TAM)-mediated tumor development. Therefore, significant efforts are urgently needed to identify pathophysiological function of YKL-40 in the dynamic interaction between tumor cells and TAMs in the tumor microenvironment, which may offer substantial mechanistic insights into tumor angiogenesis and metastasis, and also point to a therapeutic target for treatment of cancers and other diseases.