Decorin regulates collagen fibrillogenesis during corneal wound healing in mouse in vivo.

A characteristic rigid spatial arrangement of collagen fibrils in the stroma is critical for corneal transparency. This unique organization of collagen fibrils in corneal stroma can be impacted by the presence and interactions of proteoglycans and extracellular matrix (ECM) proteins in a corneal microenvironment. Earlier studies revealed that decorin, a leucine-rich proteoglycan in stroma, regulates keratocyte-collagen matrix assembly and wound healing in the cornea. This study investigated the role of decorin in the regulation of stromal fibrillogenesis and corneal transparency in vivo employing a loss-of-function genetic approach using decorin null (dcn-/-) and wild type (dcn+/+) mice and a standard alkali-injury model. A time-dependent ocular examinations with Slit lamp microscope in live animals assessed corneal clarity, haze, and neovascularization levels in normal and injured eyes. Morphometric changes in normal and injured dcn+/+ and dcn-/- corneas, post-euthanasia, were analyzed with Masson's Trichrome and Periodic Acid-Schiff (PAS) histology evaluations. The ultrastructure changes in all corneas were investigated with transmission electron microscopy (TEM). Injury to eye produced clinically relevant corneal haze and neovascularization in dcn-/- and dcn+/+ mice while corneas of uninjured eyes remained clear and avascular. A clinically significant haze and neovascularization appeared in injured dcn-/- corneas compared to the dcn+/+ corneas at day 21 post-injury and not at early tested times. Histological examinations revealed noticeably abnormal morphology and compromised collagen levels in injured dcn-/- corneas compared to the injured/normal dcn+/+ and uninjured dcn-/- corneas. TEM analysis exhibited remarkably uneven collagen fibrils size and distribution in the stroma with asymmetrical organization and loose packing in injured dcn-/- corneas than injured/normal dcn+/+ and uninjured dcn-/- corneas. The minimum and maximum inter-fibril distances were markedly irregular in injured dcn-/- corneas compared to all other corneas. Together, results of clinical, histological, and ultrastructural investigations in a genetic knockout model suggested that decorin influenced stromal fibrillogenesis and transparency in healing cornea.

Decorin regulates myostatin and enhances proliferation and differentiation of embryonic myoblasts in Leizhou black duck.

Skeletal muscle is one of the most important economic traits in the poultry industry whose development goes through several processes influenced by several candidate genes. This study explored the regulatory role of DCN on MSTN and the influence of these genes on the proliferation and differentiation of embryonic myoblasts in Leizhou black ducks. Embryonic myoblasts were transfected with over-expressing DCN, Si-DCN, and empty vector and cultured for 24 h, 48 h, and 72 h of proliferation and the comparative expression of DCN and MSTN were measured. The results showed that cells transfected with the over-expression DCN had a significantly (P < 0.05) higher expression of DCN mRNA than the normal group and the expression of MSTN mRNA showed a downward trend during the proliferation of myoblasts. DCN mRNA expression was lower in cells transfected with Si-DCN than the normal group in all stages of proliferation. While the expression of MSTN in the Si-DCN transfected group was higher than the normal group with a significant (P < 0.05) difference at the 72 h stage. DCN mRNA increased at the early stage of differentiation but decreased (P > 0.05) from the 6th day to the 8th day of differentiation. The level of MSTN increased gradually during the differentiation process of myoblasts until it decreased significantly on the 8th day. These results show that DCN enhances the proliferation and differentiation of Leizhou black duck myoblasts and suppresses MSTN activity.

The functional role of decorin in corneal neovascularization in vivo.

Our earlier decorin (Dcn) gene overexpression studies found that the targeted Dcn gene transfer into the cornea inhibited corneal angiogenesis in vivo using a rabbit model. In this study, we tested the hypothesis that anti-angiogenic effects of decorin in the cornea are mediated by alterations in a normal physiologic balance of pro- and anti-angiogenic factors using decorin deficient (Dcn-/-) and wild type (Dcn+/+) mice. Corneal neovascularization (CNV) in Dcn-/- and Dcn+/+ mice was produced with a standard chemical injury technique. The clinical progression of CNV in mice was monitored with stereo- and slit-lamp microscopes, and histopathological hematoxylin and eosin (H&E) staining. Protein and mRNA expression of pro- and anti-angiogenic factors in the cornea were evaluated using immunofluorescence and quantitative real-time PCR, respectively. Slit-lamp clinical eye examinations revealed significantly more CNV in Dcn-/- mice than the Dcn+/+ mice post-injury (p < 0.05) and AAV5-Dcn gene therapy significantly reduced CNV in Dcn-/- mice compered to no AAV5-Dcn gene therapy controls (p < 0.001). H&E-stained corneal sections exhibited morphology with several neovessels in injured corneas of the Dcn-/- mice than the Dcn+/+ mice. Immunofluorescence of corneal sections displayed significantly higher expression of α-smooth muscle actin (α-SMA) and endoglin proteins in Dcn-/- mice than Dcn+/+ mice (p < 0.05). Quantitative real-time PCR found significantly increased mRNA levels of pro-angiogenic factors endoglin (2.53-fold; p < 0.05), Vegf (2.47-fold; p < 0.05), and Pecam (2.14-fold; p < 0.05) and anti-angiogenic factor Vegfr2 (1.56-fold; p < 0.05) in the normal cornea of the Dcn-/- mice than the Dcn+/+ mice. Furthermore, neovascularized Dcn-/- mice corneas showed greater increase in mRNA expression of pro-angiogenic factors endoglin (4.58-fold; p < 0.0001), Vegf (4.16-fold; p < 0.0001), and Pdgf (2.15-fold; p < 0.0001) and reduced expression of anti-angiogenic factors Ang2 (0.12-fold; p < 0.05), Timp1 (0.22-fold; p < 0.05), and Vegfr2 (0.67-fold; p > 0.05) compared to neovascularized Dcn+/+ mice corneas. These gene deficience studies carried with transgenic Dcn-/- mice revealed decorin's role in influencing a physiologic balance between pro-and anti-angiogenic factors in the normal and injured cornea. We infer that the functional deletion of Dcn promotes irregular corneal repair and aggravates CNV.

The "other" 15-40%: The Role of Non-Collagenous Extracellular Matrix Proteins and Minor Collagens in Tendon.

Extracellular matrix (ECM) determines the physiological function of all tissues, including musculoskeletal tissues. In tendon, ECM provides overall tissue architecture, which is tailored to match the biomechanical requirements of their physiological function, that is, force transmission from muscle to bone. Tendon ECM also constitutes the microenvironment that allows tendon-resident cells to maintain their phenotype and that transmits biomechanical forces from the macro-level to the micro-level. The structure and function of adult tendons is largely determined by the hierarchical organization of collagen type I fibrils. However, non-collagenous ECM proteins such as small leucine-rich proteoglycans (SLRPs), ADAMTS proteases, and cross-linking enzymes play critical roles in collagen fibrillogenesis and guide the hierarchical bundling of collagen fibrils into tendon fascicles. Other non-collagenous ECM proteins such as the less abundant collagens, fibrillins, or elastin, contribute to tendon formation or determine some of their biomechanical properties. The interfascicular matrix or endotenon and the outer layer of tendons, the epi- and paratenon, includes collagens and non-collagenous ECM proteins, but their function is less well understood. The ECM proteins in the epi- and paratenon may provide the appropriate microenvironment to maintain the identity of distinct tendon cell populations that are thought to play a role during repair processes after injury. The aim of this review is to provide an overview of the role of non-collagenous ECM proteins and less abundant collagens in tendon development and homeostasis. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:23-35, 2020.

Decorin age-related variations in the distribution of pig extracellular matrix meniscus.

Menisci act like shock absorbers and transmit load across the tibiofemoral joint by increasing congruency during movements or body weight load. This leads to decreasing the resultant stress on the articular cartilages. The meniscus has a dense extracellular matrix (ECM) composed of water, different types of collagens, and proteoglycans, such as decorin, aggrecan and biglycan. Decorin (DCN) regulates collagen fibrillogenesis acting on collagen fibrils diameter and fibrils orientation to achieve the proper assembly of its network. This work investigates the spatial disposition of this fundamental protein in pig meniscus' matrix by immunohistochemistry and western blot analysis. DCN shows an increasing trend, moving from neonatal to adult pig menisci. Adult meniscus, in porcine species, is the only one that could be considered fully mature and functional, and, even if an increasing trend is seen, no precise phenotypical switch points are seen in the age stages considered in this study.

Absence of the proteoglycan decorin reduces glucose tolerance in overfed male mice.

Studies have implicated the extracellular matrix (ECM) of adipose tissue in insulin resistance. The proteoglycan decorin, a component of ECM, has been associated with glucose tolerance, but possible causal effects on metabolism remain to be explored. We here sought to determine metabolic consequences of loss of decorin in mice (DcnKO). DcnKO mice were fed a low-fat (LF) or high-fat (HF) diet for 10 weeks and body weight and food intake was recorded. An intraperitoneal glucose tolerance test was performed after eight weeks. Blood samples and adipose, liver and muscle tissues were collected at sacrifice. Global gene expression was measured in adipose tissue, and expression of decorin was also analyzed in human adipose samples. DcnKO mice showed increased feed efficiency during overfeeding and impaired glucose tolerance. Adipose leptin mRNA and circulating leptin levels were elevated in DcnKO mice, along with a downregulation of genes involved in ECM organization and triglyceride biosynthesis, and an upregulation of adipose genes involved in complement and coagulation cascades. Consistent with a protective metabolic role for decorin, in obese patients we found increased adipose decorin expression after profound fat loss, particularly in the stromal vascular fraction. Loss of decorin in mice caused impaired glucose tolerance in association with increased feed efficiency and altered gene expression in adipose tissue. Our data provide evidence that decorin is an important factor for maintaining glucose tolerance.

Decorin antagonizes corneal fibroblast migration via caveolae-mediated endocytosis of epidermal growth factor receptor.

Decorin (Dcn), a small leucine-rich proteoglycan, is involved in the regulation of corneal wound healing. Epidermal growth factor receptor (EGFR) plays a critical role in corneal fibroblasts proliferation, migration and extracellular matrix (ECM) modulation upon injury or infection. The present study aimed to investigate the mechanistic role of Dcn in EGFR internalization to the regulation of corneal stromal fibroblasts (CSFs) migration, a key step in the corneal wound healing. Human corneal stromal fibroblasts (hCSF) cultures were generated from donor corneas. At 70% confluence, cells were switched to serum-free conditions for 48 h and then treated with decorin (250 nM) in the presence or absence of EGF (100 ng/ml) for various time points (10-60 min). Cell lysates were subjected to proteome array analysis screening for 42 different phosphorylated human receptor tyrosine kinases (RTKs), immunocytochemistry, and western blots to analyze EGFR phosphorylation. The scratch-wound assay was performed to evaluate the effects of decorin on EGF-mediated hCSF migration. Dcn caused a rapid EGFR phosphorylation within 10 min of exposure in RTK blot defining its role as a biological ligand for EGFR in hCSFs. Prolonged exposure to Dcn caused complete disappearance of EGFR and inhibition of the hCSF migration in the scratch wound assay suggesting Dcn binding to EGFR causes EGFR down-regulation. Immunostaining studies indicated that Dcn-treatment to hCSFs internalizes Dcn-EGFR complex, which does not require tyrosine kinase activity when treated with the AG1478 inhibitor and co-localizes the complex to the perinuclear region. Next, we found that Dcn-EGFR complex does not follow canonical early endosome internalization as revealed by the EEA1 antibody instead binds to the CD63 antibody directed for degradation by the late endosome. We also found that Dcn regulates the EGFR recycling by preventing its binding to Rab11, a specific antibody for recycling endosome. Further, hCSFs-pretreated with pharmacological inhibitors, methyl-ß-cyclodextrin and chlorpromazine and supplemented with Dcn suggested EGFR trafficking via the caveolae-mediated pathway. These results suggest that Dcn acts as a biological ligand for EGFR and modulates hCSF migration via EGFR down-regulation, thus playing a vital role in corneal wound healing.

A nutrient sentinel stands guard outside the cell.

Nutrient sensing is a critical cell function that regulates survival and growth by adjusting metabolism. During nutrient shortage, autophagy enables the recycling of major cellular components to prevent cell death. Understanding the mechanisms that trigger and control autophagy is of fundamental importance, as this degradative pathway plays a pivotal role in many diseases. Gubbiotti et al. report the identification of a new player, the proteoglycan decorin, which functions as a nutrient sensor in the extracellular matrix and controls autophagy in the heart.

Metabolic reprogramming of murine cardiomyocytes during autophagy requires the extracellular nutrient sensor decorin.

The extracellular matrix is a master regulator of tissue homeostasis in health and disease. Here we examined how the small, leucine-rich, extracellular matrix proteoglycan decorin regulates cardiomyocyte metabolism during fasting in vivo First, we validated in Dcn-/- mice that decorin plays an essential role in autophagy induced by fasting. High-throughput metabolomics analyses of cardiac tissue in Dcn-/- mice subjected to fasting revealed striking differences in the hexosamine biosynthetic pathway resulting in aberrant cardiac O-ß-N-acetylglycosylation as compared with WT mice. Functionally, Dcn-/- mice maintained cardiac function at a level comparable with nonfasted animals whereas fasted WT mice showed reduced ejection fraction. Collectively, our results suggest that reduced sensing of nutrient deprivation in the absence of decorin preempts functional adjustments of cardiac output associated with metabolic reprogramming.

Decorin interacting network: A comprehensive analysis of decorin-binding partners and their versatile functions.

Decorin, a prototype small leucine-rich proteoglycan, regulates a vast array of cellular processes including collagen fibrillogenesis, wound repair, angiostasis, tumor growth, and autophagy. This functional versatility arises from a wide array of decorin/protein interactions also including interactions with its single glycosaminoglycan side chain. The decorin-binding partners encompass numerous categories ranging from extracellular matrix molecules to cell surface receptors to growth factors and enzymes. Despite the diversity of the decorin interacting network, two main roles emerge as prominent themes in decorin function: maintenance of cellular structure and outside-in signaling, culminating in anti-tumorigenic effects. Here we present contemporary knowledge regarding the decorin interacting network and discuss in detail the biological relevance of these pleiotropic interactions, some of which could be targeted by therapeutic interventions.

Microenvironmental Modulation of Decorin and Lumican in Temozolomide-Resistant Glioblastoma and Neuroblastoma Cancer Stem-Like Cells.

The presence of cancer stem cells (CSCs) or tumor-initiating cells can lead to cancer recurrence in a permissive cell-microenvironment interplay, promoting invasion in glioblastoma (GBM) and neuroblastoma (NB). Extracellular matrix (ECM) small leucine-rich proteoglycans (SLRPs) play multiple roles in tissue homeostasis by remodeling the extracellular matrix (ECM) components and modulating intracellular signaling pathways. Due to their pan-inhibitory properties against receptor tyrosine kinases (RTKs), SLRPs are reported to exert anticancer effects in vitro and in vivo. However, their roles seem to be tissue-specific and they are also involved in cancer cell migration and drug resistance, paving the way to complex different scenarios. The aim of this study was to determine whether the SLRPs decorin (DCN) and lumican (LUM) are recruited in cell plasticity and microenvironmental adaptation of differentiated cancer cells induced towards stem-like phenotype. Floating neurospheres were generated by applying CSC enrichment medium (neural stem cell serum-free medium, NSC SFM) to the established SF-268 and SK-N-SH cancer cell lines, cellular models of GBM and NB, respectively. In both models, the time-dependent synergistic activation of DCN and LUM was observed. The highest DCN and LUM mRNA/protein expression was detected after cell exposure to NSC SFM for 8/12 days, considering these cells as SLRP-expressing (SLRP+) CSC-like. Ultrastructural imaging showed the cellular heterogeneity of both the GBM and NB neurospheres and identified the inner living cells. Parental cell lines of both GBM and NB grew only in soft agar + NSC SFM, whereas the secondary neurospheres (originated from SLRP+ t8 CSC-like) showed lower proliferation rates than primary neurospheres. Interestingly, the SLRP+ CSC-like from the GBM and NB neurospheres were resistant to temozolomide (TMZ) at concentrations >750 µM. Our results suggest that GBM and NB CSC-like promote the activation of huge quantities of SLRP in response to CSC enrichment, simultaneously acquiring TMZ resistance, cellular heterogeneity, and a quiescent phenotype, suggesting a novel pivotal role for SLRP in drug resistance and cell plasticity of CSC-like, allowing cell survival and ECM/niche modulation potential.

Deficiency of decorin induces expression of Foxp3 in CD4⁺CD25⁺ T cells in a murine model of allergic asthma.

BACKGROUND AND OBJECTIVE: Decorin (Dcn), an extracellular matrix proteoglycan, has several important biological functions, and its deposition is altered in the airway wall of humans with asthma and animal models of asthma. Due to its high affinity for transforming growth factor beta (TGF)-ß, Dcn can function as part of a negative feedback mechanism, resulting in the regulation of this factor's bioavailability. Dcn deficient (Dcn(-/-) ) mice develop reduced airway inflammation, hyperresponsiveness and remodeling in response to repeated allergen challenge; we investigated whether regulatory T cells play a role in the diminished airway response of Dcn(-/-) mice. METHODS: Dcn(-/-) and Dcn(+/+) mice (C57Bl/6) were sensitized with ovalbumin (OVA) and challenged intra-nasally 3 days/week × 3 weeks. After allergen challenge, bronchoalveolar lavage was collected to quantify total and differential cell counts and cytokine levels. Inflammatory cell number and cytokine messenger ribonucleic acid (mRNA) production were assessed in lung tissues. Cells from lung and spleen were extracted to evaluate regulatory T cells. RESULTS: Tissue inflammation and interleukin (IL)-13 mRNA expression were significantly increased in OVA-challenged Dcn(+/+) mice, only. The increased expression of Foxp3 in CD4(+) CD25(+) T cells found in lung of OVA-challenged Dcn(-/-) mice was accompanied by an increase in IL-10 mRNA. CONCLUSIONS: Our data demonstrated that a diminished lung inflammation in OVA challenged Dcn(-/-) mice was accompanied by a higher expression of regulatory T cells and IL-10 mRNA levels. These results reinforce the importance of Dcn in biological processes, particularly in an allergic model of asthma.

Role of decorin in multiple myeloma (MM) bone marrow microenvironment.

Decorin is a small, leucine-rich proteoglycan found in the extracellular matrix of various connective tissues with potential effective tumor suppressive properties. Recent data suggest low levels of decorin in multiple myeloma (MM) patients compared to healthy volunteers, as well as in patients with osteolytic bone lesions compared to non-osteolytic lesions. In the present report, we investigated the role of decorin in the MM microenvironment or niche. Our data suggests that decorin is produced by osteoblasts (OBs) but not by MM cells. Furthermore, MM cells decrease OB-induced decorin secretion and this effect is mediated by CCL3. Importantly, neutralizing CCL3 from MM cells restores decorin levels in OBs as does proteasome inhibitors such as carfilzomib. These findings indicate that decorin may indirectly act as an antagonist to MM cell survival and that the interplay between MM and decorin may be an important target to explore in manipulating the tumor niche to inhibit tumorigenesis.

Decorin is responsible for progression of non-small-cell lung cancer by promoting cell proliferation and metastasis.

Decorin, a member of the small leucine-rich proteoglycans family, exists and plays multifunctional roles in stromal and epithelial cells. Emerging evidences showed that decorin is dysregulated expression in a wide variety of human tumors and affects a broad biology process of cancer cells, including growth, metastasis, and angiogenesis. Recent studies demonstrated that decorin could affect A549 proliferation though decreasing TGF-ß1, cycling D1 expression and increasing P53 and P21 expression. However, limited data are available on the effect of decorin on metastasis of non-small-cell lung cancer (NSCLC) cell lines and how decorin impacts metastasis is still unknown. In this study, we identified decorin mRNA expression through Oncomine database and verified the expression of decorin mRNA and protein in 50 patients who underwent primary surgical resection of a NSCLC in the Department of Thoracic Surgery, Jinling Hospital, Nanjing University School of Medicine, China, between September 2013 and March 2014 by quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) and Western blot. Also, the correlationship between decorin and the NSCLC patients' clinical characteristics or survival ( www.kmplot.com ) was analyzed. Via ectopic expression analyses and Western blot, the roles of decorin in proliferation, metastasis, and the underline mechanism for decorin expression were further explored. We found that decorin was downregulated in NSCLC tissues compared with the adjacent normal lung tissues or normal tissues. Additionally, the expression of decorin was correlated with tumor size, lymph node metastasis, tumor stage, and prognosis. We also showed that overexpression of decorin could inhibit NSCLC cell lines proliferation and metastasis. Through Western blot analysis, we identified that E-cadherin and vascular endothelial growth factor (VEGF) are two key factors responsible for the growth arrest and metastasis inhibition induced by decorin in NSCLC. Our results indicated that decorin plays crucial roles in NSCLC against carcinogenesis and progression. Decorin might be a predictive factor and an attractive therapeutic target for NSCLC patients.

Decorin induced by progesterone plays a crucial role in suppressing endometriosis.

Dienogest, a synthetic progestin, has been shown to be effective against endometriosis, although it is still unclear as to how it affects the ectopic endometrial cells. Decorin has been shown to be a powerful endogenous tumor repressor acting in a paracrine fashion to limit tumor growth. Our objectives were to examine the direct effects of progesterone and dienogest on the in vitro proliferation of the human ectopic endometrial epithelial and stromal cell lines, and evaluate as to how decorin contributes to this effect. We also examined DCN mRNA expression in 50 endometriosis patients. The growth of both cell lines was inhibited in a dose-dependent manner by both decorin and dienogest. Using a chromatin immunoprecipitation assay, it was noted that progesterone and dienogest directly induced the binding of the decorin promoter in the EMOsis cc/TERT cells (immortalized human ovarian epithelial cells) and CRL-4003 cells (immortalized human endometrial stromal cells). Progesterone and dienogest also led to significant induced cell cycle arrest via decorin by promoting production of p21 in both cell lines in a dose-dependent manner. Decorin also suppressed the expression of MET in both cell lines. We confirmed that DCN mRNA expression in patients treated with dienogest was higher than that in the control group. In conclusion, decorin induced by dienogest appears to play a crucial role in suppressing endometriosis by exerting anti-proliferative effects and inducing cell cycle arrest via the production of p21 human ectopic endometrial cells and eutopic endometrial stromal cells.

Decorin mimic regulates platelet-derived growth factor and interferon-γ stimulation of vascular smooth muscle cells.

Following balloon injury, smooth muscle cells (SMCs) serve as targets for many of the pro-inflammatory and pro-fibrotic factors, including platelet-derived growth factor (PDGF) and interferon-γ (IFN-γ) released from activated inflammatory cells and platelets. Previously, our lab designed a mimic of the proteoglycan decorin, termed DS-SILY20, that suppressed vascular SMC proliferation, migration, and protein synthesis in vitro, and injured vessels treated with DS-SILY20 demonstrated reduced hyperplasia in vivo. Here we characterize the effects of DS-SILY20 on modulating PDGF and IFN-γ stimulation in both proliferative and quiescent human SMCs to further evaluate the potential impact of DS-SILY20-SMC interaction on restenosis. Nanomolar dissociation constants were observed between DS-SILY20 and both PDGF and IFN-γ. PDGF significantly increased migration, proliferation, and protein and cytokine expression, as well as increased ERK-1/2 and p38 MAPK phosphorylation in both quiescent and proliferative cultures. However, DS-SILY20 inhibited these increases, presumably through sequestration of the PDGF. Consistent with the complex responses seen with IFN-γ in SMC physiology in the literature, the response of SMC cultures to IFN-γ was variable and complex. However, where increased activity was seen with IFN-γ, DS-SILY20 attenuated this activity. Overall, the results suggest that DS-SILY20 would be an ideal alternative to traditional therapeutics used and may be an effective therapy for the prevention of intimal hyperplasia after balloon angioplasty.

Intratumoral decorin gene delivery by AAV vector inhibits brain glioblastomas and prolongs survival of animals by inducing cell differentiation.

Glioblastoma multiforme (GBM) is the most malignant cancer in the central nervous system with poor clinical prognosis. In this study, we investigated the therapeutic effect of an anti-cancer protein, decorin, by delivering it into a xenograft U87MG glioma tumor in the brain of nude mice through an adeno-associated viral (AAV2) gene delivery system. Decorin expression from the AAV vector in vitro inhibited cultured U87MG cell growth by induction of cell differentiation. Intracranial injection of AAV-decorin vector to the glioma-bearing nude mice in vivo significantly suppressed brain tumor growth and prolonged survival when compared to control non-treated mice bearing the same U87MG tumors. Proteomics analysis on protein expression profiles in the U87MG glioma cells after AAV-mediated decorin gene transfer revealed up- and down-regulation of important proteins. Differentially expressed proteins between control and AAV-decorin-transduced cells were identified through MALDI-TOF MS and database mining. We found that a number of important proteins that are involved in apoptosis, transcription, chemotherapy resistance, mitosis, and fatty acid metabolism have been altered as a result of decorin overexpression. These findings offer valuable insight into the mechanisms of the anti-glioblastoma effects of decorin. In addition, AAV-mediated decorin gene delivery warrants further investigation as a potential therapeutic approach for brain tumors.

Decorin-mediated inhibition of cholangiocarcinoma cell growth and migration and promotion of apoptosis are associated with E-cadherin in vitro.

Emerging evidences have shown that decorin expression is significantly reduced in many cancer tissues and cancer cells. However, its biological role and clinical significance in cholangiocarcinoma development and progression are unknown. In this study, immunohistochemistry was conducted to investigate the expression of decorin in cholangiocarcinomas. The results showed that decorin levels markedly decreased in 44 cholangiocarcinoma tissues compared to 40 adjacent normal tissues. The analysis between decorin expression and clinicopathological characteristics in cholangiocarcinoma patients showed that patients with low levels of decorin expression had a relatively poor prognosis. Moreover, recombinant human decorin treatment and overexpression of decorin in cholangiocarcinoma cells could inhibit cell proliferation, migration, and invasion and promote apoptosis. Furthermore, the E-cadherin expression significantly increased after decorin overexpression or use of recombinant human decorin in cholangiocarcinoma cells. Our findings indicated that downregulation of decorin may be identified as a poor prognostic biomarker in cholangiocarcinomas. Also, decorin-mediated inhibition of cholangiocarcinoma cell growth, migration, and invasion and promotion of cell apoptosis might be through regulation of the expression of E-cadherin in vitro.

Decorin mimic inhibits vascular smooth muscle proliferation and migration.

Over the past 10 years, the number of percutaneous coronary intervention procedures performed in the United States increased by 33%; however, restenosis, which inhibits complete functional recovery of the vessel wall, complicates this procedure. A wide range of anti-restenotic therapeutics have been developed, although many elicit non-specific effects that compromise vessel healing. Drawing inspiration from biologically-relevant molecules, our lab developed a mimic of the natural proteoglycan decorin, termed DS-SILY, which can mask exposed collagen and thereby effectively decrease platelet activation, thus contributing to suppression of vascular intimal hyperplasia. Here, we characterize the effects of DS-SILY on both proliferative and quiescent human SMCs to evaluate the potential impact of DS-SILY-SMC interaction on restenosis, and further characterize in vivo platelet interactions. DS-SILY decreased proliferative SMC proliferation and pro-inflammatory cytokine secretion in vitro in a concentration dependent manner as compared to untreated controls. The addition of DS-SILY to in vitro SMC cultures decreased SMC migration and protein synthesis by 95% and 37%, respectively. Furthermore, DS-SILY decreased platelet activation, as well as reduced neointimal hyperplasia by 60%, in vivo using Ossabaw swine. These results indicate that DS-SILY demonstrates multiple biological activities that may all synergistically contribute to an improved treatment paradigm for balloon angioplasty.

Decorin causes autophagy in endothelial cells via Peg3.

Soluble decorin affects the biology of several receptor tyrosine kinases by triggering receptor internalization and degradation. We found that decorin induced paternally expressed gene 3 (Peg3), an imprinted tumor suppressor gene, and that Peg3 relocated into autophagosomes labeled by Beclin 1 and microtubule-associated light chain 3. Decorin evoked Peg3-dependent autophagy in both microvascular and macrovascular endothelial cells leading to suppression of angiogenesis. Peg3 coimmunoprecipitated with Beclin 1 and LC3 and was required for maintaining basal levels of Beclin 1. Decorin, via Peg3, induced transcription of Beclin 1 and microtubule-associated protein 1 light chain 3 alpha genes, thereby leading to a protracted autophagic program. Mechanistically, decorin interacted with VEGF receptor 2 (VEGFR2) in a region overlapping with its natural ligand VEGFA, and VEGFR2 was required for decorin-evoked Beclin 1 and microtubule-associated protein 1 light chain 3 alpha expression as well as for Peg3 induction in endothelial cells. Moreover, decorin induced VEGFR2-dependent mitochondrial fragmentation and loss of mitochondrial membrane potential. Thus, we have unveiled a mechanism for a secreted proteoglycan in inducing Peg3, a master regulator of macroautophagy in endothelial cells.