Key Extracellular Matrix Proteins Research Articles

Neutrophil-Derived Peptidyl Arginine Deiminase Activity Contributes to Pulmonary Emphysema by Enhancing Elastin Degradation.

In chronic obstructive pulmonary disease (COPD), inflammation gives rise to protease-mediated degradation of the key extracellular matrix protein, elastin, which causes irreversible loss of pulmonary function. Intervention against proteolysis has met with limited success in COPD, due in part to our incomplete understanding of the mechanisms that underlie disease pathogenesis. Peptidyl arginine deiminase (PAD) enzymes are a known modifier of proteolytic susceptibility, but their involvement in COPD in the lungs of affected individuals is underexplored. In this study, we showed that enzyme isotypes PAD2 and PAD4 are present in primary granules of neutrophils and that cells from people with COPD release increased levels of PADs when compared with neutrophils of healthy control subjects. By examining bronchoalveolar lavage and lung tissue samples of patients with COPD or matched smoking and nonsmoking counterparts with normal lung function, we reveal that COPD presents with markedly increased airway concentrations of PADs. Ex vivo, we established citrullinated elastin in the peripheral airways of people with COPD, and invitro, elastin citrullination significantly enhanced its proteolytic degradation by serine and matrix metalloproteinases, including neutrophil elastase and matrix metalloprotease-12, respectively. These results provide a mechanism by which neutrophil-released PADs affect lung function decline, indicating promise for the future development of PAD-based therapeutics for preserving lung function in patients with COPD.

Laminin-associated integrins mediate Diffuse Intrinsic Pontine Glioma infiltration and therapy response within a neural assembloid model

Diffuse Intrinsic Pontine Glioma (DIPG) is a highly aggressive and fatal pediatric brain cancer. One pre-requisite for tumor cells to infiltrate is adhesion to extracellular matrix (ECM) components. However, it remains largely unknown which ECM proteins are critical in enabling DIPG adhesion and migration and which integrin receptors mediate these processes. Here, we identify laminin as a key ECM protein that supports robust DIPG cell adhesion and migration. To study DIPG infiltration, we developed a DIPG-neural assembloid model, which is composed of a DIPG spheroid fused to a human induced pluripotent stem cell-derived neural organoid. Using this assembloid model, we demonstrate that knockdown of laminin-associated integrins significantly impedes DIPG infiltration. Moreover, laminin-associated integrin knockdown improves DIPG response to radiation and HDAC inhibitor treatment within the DIPG-neural assembloids. These findings reveal the critical role of laminin-associated integrins in mediating DIPG progression and drug response. The results also provide evidence that disrupting integrin receptors may offer a novel therapeutic strategy to enhance DIPG treatment outcomes. Finally, these results establish DIPG-neural assembloid models as a powerful tool to study DIPG disease progression and enable drug discovery.

Abstract PO4-24-07: The Impact of GPER Modulation on Cancer Associated Fibroblasts on Extracellular Matrix Formation in Breast Cancer

Abstract Background: The G-protein coupled estrogen receptor (GPER) is a noncanonical estrogen receptor (ER) that is estimated to be present in roughly 50-60% of all breast cancer (BC) subtypes. Previous studies have suggested that the presence of GPER during primary disease aids in disease progression, metastasis, as well as chemotherapy resistance due to the agonistic activity of traditional chemotherapies for ER+ BC, tamoxifen and fulvestrant. It is also well established that the extracellular matrix (ECM), specifically collagen, contributes to the overall risk and progression of BC in patients. Importantly, fibroblasts are one of the primary cell types responsible for ECM deposition in the tumor microenvironment. We hypothesize that the modulation of cancer-associated fibroblasts (CAFs) via estrogen signaling through GPER regulates the deposition and structure of key ECM proteins, such as collagen, to aid in disease progression. Methods: CAFs, isolated from human BC surgical resections, were plated at 100% confluency, and incubated with either 10nM β-estradiol (E2), 50nM G1 (a GPER specific agonist) or a vehicle control and 50ug/mL ascorbic acid daily for 14 days to induce matrix deposition. Phenol-free, high glucose DMEM with 10% charcoal stripped FBS was used as media to reduce FBS sourced estrogen. Following the 14-day incubation, cell proliferation was quantified prior to extracting the cells to isolate the CAF-derived matrix (CDM). The organization and composition of ECM was analyzed in CDMs through immunofluorescence (IF) or western blot, respectively. An unpaired t-test was conducted on biological triplicates and between vehicle control and either G1 or E2. Significance was determined as p< 0.05. Results: Culturing CAFs with E2 resulted in a 10% increase in cell proliferation (n=3, p< 0.05) and a 1.6-fold (n=3, p< 0.05) increase in total ECM deposition by western blot. Key ECM proteins such as collagen, fibronectin, and periostin had a 1.8, 1.3, and 1.3-fold increase, respectively (n=3, p< 0.05), in protein deposition with E2 treatment when normalized to cell number. Collagen fiber analysis of IF stained CDM for collagen resulted in a coefficient of alignment with E2 of 0.76 compared to 0.51 without (n=3 for E2 and n=6 for vehicle, p< 0.05). To confirm E2 was acting through GPER, CDMs were subsequently generated with exposure to 50nM G1, a specific GPER agonist. Collagen fiber analysis of the G1 exposed CDMs resulted in a coefficient of alignment with G1 of 0.71 compared to 0.51 without (n=3 for G1 and n=6 for vehicle, p< 0.05). Conclusions: This study demonstrates that estrogen signaling through GPER modulates the deposition of fibronectin, periostin, and collagen as well as the organization of collagen architecture. These results highlight the need to further investigate how the interplay between the ECM, GPER activity, and fibroblasts impacts breast cancer progression. Citation Format: Shelby Fertal, Brian Burkel, Fern Murdoch, Kathy O'Leary, Linda Schuler, Suzanne Ponik. The Impact of GPER Modulation on Cancer Associated Fibroblasts on Extracellular Matrix Formation in Breast Cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-24-07.

Protective effect of Inonotus obliquus polysaccharide on MGO-induced nonenzymatic glycation fibroblasts

BackgroundThe nonenzymatic glycation of fibroblasts causes functional downregulation and behavioral disorders in the skin. MethodsTo investigate the effect of Inonotus obliquus on the nonenzymatic glycation of skin, we examined the inhibition of advanced glycation end products (AGEs) using four extraction methods: n-butanol, ethyl acetate, n-hexane and aqueous alcohol precipitation. The physical properties and chemical structure of the most effective, purified, crude I. obliquus polysaccharide (IOP) were examined. The effects of IOP on carboxymethyl lysine (CML) accumulation, inflammatory factor release, reactive oxygen species (ROS) production, key extracellular matrix (ECM) protein (MMP 1, 2 and 9; FN-1, LM-5 and COL-1) mRNA expression, and cell survival, migration and adhesion were also examined via cellular assays. ResultsIOP is a polysaccharide with a molecular weight (Mw) of 2.396 × 104 (±6.626%) that is composed mainly of glucose, galactose, xylose, mannose and arabinose (29.094:21.705:14.857:9.375:7.709). In addition, a cellular antiglycation assay showed that IOP, which can promote ECM formation by inhibiting the accumulation of CML, inhibiting the release of inflammatory factors (IL-1β, IL-6, and TNF-α), inhibiting the production of reactive oxygen species (ROS), inhibiting the expression of matrix metalloproteinases (MMP-1\\-2\\-9), promoting the synthesis of ECMs (COL1, FN1, and LM5), and improving cellular dysfunction, had strong antiglycation activity at concentrations in the range of 6–24 μg/mL. ConclusionIOP effectively reduced the levels of inflammatory factors and reactive oxygen species produced by AGEs, further preventing the impairment of cell behavior (decreased migration and reduced cell adhesion) and preventing the downregulation of the expression of key extracellular matrix proteins induced by AGEs. The results indicate the potential application of IOP as an AGE inhibitor in skin care.

One Week of Single-Leg Immobilization Lowers Muscle Connective Protein Synthesis Rates in Healthy, Young Adults.

Short periods of limb immobilization lower myofibrillar protein synthesis rates. Within skeletal muscle, the extracellular matrix of connective proteins is recognized as an important factor determining the capacity to transmit contractile force. Little is known regarding the impact of immobilization and subsequent recovery on muscle connective protein synthesis rates. This study examined the impact of 1 wk of leg immobilization and 2 wk of subsequent ambulant recovery on daily muscle connective protein synthesis rates. Thirty healthy, young (24 ± 5 yr) men were subjected to 7 d of one-legged knee immobilization followed by 14 d of ambulant recovery. Deuterium oxide ingestion was applied over the entire period, and muscle biopsy samples were collected before immobilization, after immobilization, and after recovery to measure muscle connective protein synthesis rates and mRNA expression of key extracellular matrix proteins (collagen I, collagen III), glycoproteins (fibronectin, tenascin-C), and proteoglycans (fibromodulin, and decorin). A two-way repeated-measures (time-leg) ANOVA was used to compare changes in muscle connective protein synthesis rates during immobilization and recovery. During immobilization, muscle connective protein synthesis rates were lower in the immobilized (1.07 ± 0.30%·d -1 ) compared with the nonimmobilized (1.48 ± 0.44%·d -1 ; P < 0.01) leg. When compared with the immobilization period, connective protein synthesis rates in the immobilized leg increased during subsequent recovery (1.48 ± 0.64%·d -1 ; P < 0.01). After recovery, skeletal muscle collagen I, collagen III, fibronectin, fibromodulin, and decorin mRNA expression increased when compared with the postimmobilization time point (all P < 0.001). One week of leg immobilization lowers muscle connective protein synthesis rates. Muscle connective protein synthesis rates increase during subsequent ambulant recovery, which is accompanied by increased mRNA expression of key extracellular matrix proteins.

Public RNA-seq data-based identification and functional analyses reveal that MXRA5 retains proliferative and migratory abilities of dental pulp stem cells

Dental pulp stem cells (DPSC) usually remain quiescent in the dental pulp tissue; however, once the dental pulp tissue is injured, DPSCs potently proliferate and migrate into the injury microenvironment and contribute to immuno-modulation and tissue repair. However, the key molecules that physiologically support the potent proliferation and migration of DPSCs have not been revealed. In this study, we searched publicly available transcriptome raw data sets, which contain comparable (i.e., equivalently cultured) DPSC and mesenchymal stem cell data. Three data sets were extracted from the Gene Expression Omnibus database and then processed and analyzed. MXRA5 was identified as the predominant DPSC-enriched gene associated with the extracellular matrix. MXRA5 is detected in human dental pulp tissues. Loss of MXRA5 drastically decreases the proliferation and migration of DSPCs, concomitantly with reduced expression of the genes associated with the cell cycle and microtubules. In addition to the known full-length isoform of MXRA5, a novel splice variant of MXRA5 was cloned in DPSCs. Recombinant MXRA5 coded by the novel splice variant potently induced the haptotaxis migration of DPSCs, which was inhibited by microtubule inhibitors. Collectively, MXRA5 is a key extracellular matrix protein in dental pulp tissue for maintaining the proliferation and migration of DPSCs.

Proteomic Analysis of Mesenchymal Stromal Cells Secretome in Comparison to Leukocyte- and Platelet-Rich Fibrin.

Secretomes of mesenchymal stromal cells (MSCs) are emerging as a novel growth factor (GF)-based strategy for periodontal and bone regeneration. The objective of this study was to compare the secretome of human bone marrow MSC (BMSC) to that of leukocyte- and platelet-rich fibrin (L-PRF), an established GF-based therapy, in the context of wound healing and regeneration. Conditioned media from human BMSCs (BMSC-CM) and L-PRF (LPRF-CM) were subjected to quantitative proteomic analysis using liquid chromatography with tandem mass spectrometry. Global profiles, gene ontology (GO) categories, differentially expressed proteins (DEPs), and gene set enrichment (GSEA) were identified using bioinformatic methods. Concentrations of selected proteins were determined using a multiplex immunoassay. Among the proteins identified in BMSC-CM (2157 proteins) and LPRF-CM (1420 proteins), 1283 proteins were common. GO analysis revealed similarities between the groups in terms of biological processes (cellular organization, protein metabolism) and molecular functions (cellular/protein-binding). Notably, more DEPs were identified in BMSC-CM (n = 550) compared to LPRF-CM (n = 118); these included several key GF, cytokines, and extracellular matrix (ECM) proteins involved in wound healing. GSEA revealed enrichment of ECM (especially bone ECM)-related processes in BMSC-CM and immune-related processes in LPRF-CM. Similar trends for intergroup differences in protein detection were observed in the multiplex analysis. Thus, the secretome of BMSC is enriched for proteins/processes relevant for periodontal and bone regeneration. The in vivo efficacy of this therapy should be evaluated in future studies.

Matrilin-2 within a three-dimensional lysine-modified chitosan porous scaffold enhances Schwann cell migration and axonal outgrowth for peripheral nerve regeneration.

Background: Matrilin-2 is a key extracellular matrix protein involved in peripheral nerve regeneration. We sought to develop a biomimetic scaffold to enhance peripheral nerve regeneration by incorporating matrilin-2 within a chitosan-derived porous scaffold. We hypothesized that the use of such a novel biomaterial delivers microenvironmental cues to facilitate Schwann cell (SC) migration and enhance axonal outgrowth during peripheral nerve regeneration. Materials and Methods: The effect of matrilin-2 on SC migration was evaluated with agarose drop migration assay on matrilin-2 coated dishes. SC adhesion was determined with SCs cultured atop tissue culture dishes coated with matrilin-2. Various formulations of chitosan vs matrilin-2 in scaffold constructs were examined with scanning electron microscopy. The effect of the matrilin-2/chitosan scaffold on SC migration in the collagen conduits was determined by capillary migration assays. Neuronal adhesion and axonal outgrowth were evaluated with three-dimensional (3D) organotypic assay of dorsal root ganglions (DRG). DRG axonal outgrowth within the scaffolds was determined by immunofluorescence staining of neurofilaments. Results: Matrilin-2 induced SC migration and enhanced its adhesion. A formulation of 2% chitosan with matrilin-2 demonstrated an optimal 3D porous architecture for SC interaction. Matrilin-2/chitosan scaffold enabled SCs to migrate against gravity within conduits. Chemical modification of chitosan with lysine (K-chitosan) further improved DRG adhesion and axonal outgrowth than the matrilin-2/chitosan scaffold without lysine modification. Conclusion: We developed a matrilin-2/K-chitosan scaffold to mimic extracellular matrix cues and provide a porous matrix to enhance peripheral nerve regeneration. Taking advantage of matrilin-2's capability to stimulate SC migration and adhesion, we formulated a porous matrilin-2/chitosan scaffold to support axongal outgrowth. Chemical modification of chitosan with lysine further improved matrilin-2 bioactivity in the 3D scaffold. The 3D porous matrilin-2/K-chitosan scaffolds have high potential for enhancing nerve repair by stimulating SC migration, neuronal adhesion, and axonal outgrowth.

CEBPD is a master transcriptional factor for hypoxia regulated proteins in glioblastoma and augments hypoxia induced invasion through extracellular matrix-integrin mediated EGFR/PI3K pathway

Hypoxia contributes to the initiation and progression of glioblastoma by regulating a cohort of genes called hypoxia-regulated genes (HRGs) which form a complex molecular interacting network (HRG-MINW). Transcription factors (TFs) often play central roles for MINW. The key TFs for hypoxia induced reactions were explored using proteomic analysis to identify a set of hypoxia-regulated proteins (HRPs) in GBM cells. Next, systematic TF analysis identified CEBPD as a top TF that regulates the greatest number of HRPs and HRGs. Clinical sample and public database analysis revealed that CEBPD is significantly up-regulated in GBM, high levels of CEBPD predict poor prognosis. In addition, CEBPD is highly expressed in hypoxic condition both in GBM tissue and cell lines. For molecular mechanisms, HIF1α and HIF2α can activate the CEBPD promotor. In vitro and in vivo experiments demonstrated that CEBPD knockdown impaired the invasion and growth capacity of GBM cells, especially in hypoxia condition. Next, proteomic analysis identified that CEBPD target proteins are mainly involved in the EGFR/PI3K pathway and extracellular matrix (ECM) functions. WB assays revealed that CEBPD significantly positively regulated EGFR/PI3K pathway. Chromatin immunoprecipitation (ChIP) qPCR/Seq analysis and Luciferase reporter assay demonstrated that CEBPD binds and activates the promotor of a key ECM protein FN1 (fibronectin). In addition, the interactions of FN1 and its integrin receptors are necessary for CEBPD-induced EGFR/PI3K activation by promoting EGFR phosphorylation. Furthermore, GBM sample analysis in the database corroborated that CEBPD is positively correlated with the pathway activities of EGFR/PI3K and HIF1α, especially in highly hypoxic samples. At last, HRPs are also enriched in ECM proteins, indicating that ECM activities are important components of hypoxia induced responses in GBM. In conclusion, CEPBD plays important regulatory roles in the GBM HRG-MINW as a key TF, which activates the EGFR/PI3K pathway through ECM, especially FN1, mediated EGFR phosphorylation.

Bioactive Cell-Derived ECM Scaffold Forms a Unique Cellular Microenvironment for Lung Tissue Engineering.

Chronic lung diseases are one of the leading causes of death worldwide. Lung transplantation is currently the only causal therapeutic for lung diseases, which is restricted to end-stage disease and limited by low access to donor lungs. Lung tissue engineering (LTE) is a promising approach to regenerating a replacement for at least a part of the damaged lung tissue. Currently, lung regeneration is limited to a simplified local level (e.g., alveolar–capillary barrier) due to the sophisticated and complex structure and physiology of the lung. Here, we introduce an extracellular matrix (ECM)-integrated scaffold using a cellularization–decellularization–recellularization technique. This ECM-integrated scaffold was developed on our artificial co-polymeric BETA (biphasic elastic thin for air–liquid interface cell culture conditions) scaffold, which were initially populated with human lung fibroblasts (IMR90 cell line), as the main generator of ECM proteins. Due to the interconnected porous structure of the thin (<5 µm) BETA scaffold, the cells can grow on and infiltrate into the scaffold and deposit their own ECM. After a mild decellularization procedure, the ECM proteins remained on the scaffold, which now closely mimicked the cellular microenvironment of pulmonary cells more realistically than the plain artificial scaffolds. We assessed several decellularization methods and found that 20 mM NH4OH and 0.1% Triton X100 with subsequent DNase treatment completely removed the fibroblasts (from the first cellularization) and maintains collagen I and IV as the key ECM proteins on the scaffold. We also showed the repopulation of the primary fibroblast from human (without chronic lung disease (non-CLD) donors) and human bronchial epithelial (16HBE14o−) cells on the ECM-integrated BETA scaffold. With this technique, we developed a biomimetic scaffold that can mimic both the physico-mechanical properties and the native microenvironment of the lung ECM. The results indicate the potential of the presented bioactive scaffold for LTE application.

Simvastatin inhibits stem cell proliferation in human leiomyoma via TGF‐β3 and Wnt/β‐Catenin pathways

Uterine leiomyoma (UL) is the most common gynaecologic tumour, affecting an estimated 70 to 80% of women. Leiomyomas develop from the transformation of myometrial stem cells into leiomyoma stem (or tumour‐initiating) cells. These cells undergo self‐renewal and differentiation to mature cells, both are necessary for the maintenance of tumour stem cell niche and tumour growth, respectively. Wnt/β‐catenin and TGF‐β/SMAD pathways, both overactive in UL, promote stem cell self‐renewal, crosstalk between stem and mature cells, cellular proliferation, extracellular matrix (ECM) accumulation and drive overall UL growth. Recent evidence suggests that simvastatin, an antihyperlipidemic drug, may have anti‐leiomyoma properties. Herein, we investigated the effects of simvastatin on UL stem cells. We isolated leiomyoma stem cells by flow cytometry using DyeCycle Violet staining and Stro‐1/CD44 surface markers. We found that simvastatin inhibits proliferation and induces apoptosis in UL stem cells. In addition, it also suppressed the expression of the stemness markers Nanog, Oct4 and Sox2. Simvastatin significantly decreased the production of the key ECM proteins, collagen 1 and fibronectin. Finally, it inhibited genes and/or proteins expression of TGF‐β1, 2 and 3, SMAD2, SMAD4, Wnt4, β‐Catenin, LRP6, AXIN2 and Cyclin D1 in UL stem cells, all are key drivers of the TGF‐β3/SMAD2 and Wnt4/β‐Catenin pathways. Thus, we have identified a novel stem cell‐targeting anti‐leiomyoma simvastatin effect. Further studies are needed to replicate these findings in vivo.

Extracellular matrix remodeling through endocytosis and resurfacing of Tenascin-R

The brain extracellular matrix (ECM) consists of extremely long-lived proteins that assemble around neurons and synapses, to stabilize them. The ECM is thought to change only rarely, in relation to neuronal plasticity, through ECM proteolysis and renewed protein synthesis. We report here an alternative ECM remodeling mechanism, based on the recycling of ECM molecules. Using multiple ECM labeling and imaging assays, from super-resolution optical imaging to nanoscale secondary ion mass spectrometry, both in culture and in brain slices, we find that a key ECM protein, Tenascin-R, is frequently endocytosed, and later resurfaces, preferentially near synapses. The TNR molecules complete this cycle within ~3 days, in an activity-dependent fashion. Interfering with the recycling process perturbs severely neuronal function, strongly reducing synaptic vesicle exo- and endocytosis. We conclude that the neuronal ECM can be remodeled frequently through mechanisms that involve endocytosis and recycling of ECM proteins.

Nidogen-2 Maintains the Contractile Phenotype of Vascular Smooth Muscle Cells and Prevents Neointima Formation via Bridging Jagged1-Notch3 Signaling.

How the extracellular matrix (ECM) microenvironment modulates the contractile phenotype of vascular smooth muscle cells (VSMCs) and confers vascular homeostasis remains elusive. To explore the key ECM proteins in the maintenance of the contractile phenotype of VSMCs, we applied protein-protein interaction network analysis to explore novel ECM proteins associated with the VSMC phenotype. By combining in vitro and in vivo genetic mice vascular injury models, we identified nidogen-2, a basement membrane glycoprotein, as a key ECM protein for maintenance of vascular smooth muscle cell identity. We collected a VSMC phenotype-related gene dataset by using Gene Ontology annotation combined with a literature search. A computational analysis of protein-protein interactions between ECM protein genes and the genes from the VSMC phenotype-related gene dataset revealed the candidate gene nidogen-2, a basement membrane glycoprotein involved in regulation of the VSMC phenotype. Indeed, nidogen-2-deficient VSMCs exhibited loss of contractile phenotype in vitro, and compared with wild-type mice, nidogen-2-/- mice showed aggravated post-wire injury neointima formation of carotid arteries. Further bioinformatics analysis, coimmunoprecipitation assays, and luciferase assays revealed that nidogen-2 specifically interacted with Jagged1, a conventional Notch ligand. Nidogen-2 maintained the VSMC contractile phenotype via Jagged1-Notch3 signaling but not Notch1 or Notch2 signaling. Nidogen-2 enhanced Jagged1 and Notch3 interaction and subsequent Notch3 activation. Reciprocally, Jagged1 and Notch3 interaction, signaling activation, and Jagged1-triggered VSMC differentiation were significantly repressed in nidogen-2-deficient VSMCs. In accordance, the suppressive effect of Jagged1 overexpression on neointima formation was attenuated in nidogen-2-/- mice compared with wild-type mice. Nidogen-2 maintains the contractile phenotype of VSMCs through Jagged1-Notch3 signaling in vitro and in vivo. Nidogen-2 is required for Jagged1-Notch3 signaling.

An artificial membrane binding protein-polymer surfactant nanocomplex facilitates stem cell adhesion to the cartilage extracellular matrix

One of the major challenges within the emerging field of injectable stem cell therapies for articular cartilage (AC) repair is the retention of sufficient viable cell numbers at the site of injury. Even when delivered via intra-articular injection, the number of stem cells retained at the target is often low and declines rapidly over time. To address this challenge, an artificial plasma membrane binding nanocomplex was rationally designed to provide human mesenchymal stem cells (hMSCs) with increased adhesion to articular cartilage tissue. The nanocomplex comprises the extracellular matrix (ECM) binding peptide of a placenta growth factor-2 (PlGF-2) fused to a supercharged green fluorescent protein (scGFP), which was electrostatically conjugated to anionic polymer surfactant chains to yield [S−]scGFP_PlGF2. The [S−]scGFP_PlGF2 nanocomplex spontaneously inserts into the plasma membrane of hMSCs, is not cytotoxic, and does not inhibit differentiation. The nanocomplex-modified hMSCs showed a significant increase in affinity for immobilised collagen II, a key ECM protein of cartilage, in both static and dynamic cell adhesion assays. Moreover, the cells adhered strongly to bovine ex vivo articular cartilage explants resulting in high cell numbers. These findings suggest that the re-engineering of hMSC membranes with [S−]scGFP_PlGF2 could improve the efficacy of injectable stem cell-based therapies for the treatment of damaged articular cartilage.

Abstract PO030: A novel integrin-targeted therapeutic agent for prostate cancer

Abstract Disintegrins are disulfide-rich peptides, many containing an Arg-Gly-Asp (RGD) motif. They hold significant translational potential as anti-cancer agents based on their high-affinity/high-specificity interaction with tumor integrins and desirable pharmacological attributes. The integrin-binding activity of disintegrins depends on a mobile 11-amino acid loop displaying the RGD tripeptide motif or some other tripeptide motif. They bind only to the activated conformation of integrins on motile cancer cells and angiogenic endothelial cells. We designed a sequence-engineered RGD-disintegrin, vicrostatin (VCN), that can be produced at ~200mg/L from cell lysates of a bacterial recombinant system. VCN, a monomer (MW=7146), inhibits tumor cell adhesion and dissemination, and angiogenic endothelial cell invasion and tube formation. Integrins are cell surface adhesion receptors (containing a and b chains) operating at the interface between the extracellular matrix and cytoskeletal apparatus. A sub-group of integrins recognize the RGD sequence present in key extracellular matrix proteins involved in prostate cancer (PC) growth and dissemination. Integrins are involved in bi-directional signaling interactions that alter cellular functions. Among these interactions are those involved in PC growth, metastasis and angiogenesis. Integrin avb3 plays an important role in the development of bone metastases, supporting our belief that it, as well as other RGD-integrins, are important therapeutic targets in advanced PC. We examined the effect of treatment of a xenograft model of human PC using a liposomal formulation of VCN (LVCN). PC3 cells were implanted subcutaneously in 5-week old male nude mice. LVCN and VCN (100µg VCN equivalent per dose) administration was initiated IV when tumors became palpable (14 days). Tumor size was measured weekly by caliper in a blinded study. There was a 75% reduction in tumor growth in LVCN-treated animals compared to controls. VCN displayed little anti-tumor activity most likely due to its lack of availability to the PC cells. We also examined the anti-angiogenic activity of LVCN in this model using CD31/PECAM immunohistochemistry and observed a significant decrease in tumor-associated microvessel density. We then evaluated therapeutic efficacy of LVCN in treating bone metastases. CWR22rV1 PC cells were suspended in a solution of matrigel and injected into a drilled hole in the proximal left tibia of immunodeficient mice (100,000 cells/10µL). Following injection, the diameters of both tibias were measured by caliper twice weekly. Since CWR22rV1 cells are androgen dependent, animals received daily injections of testosterone. Tumors grew slowly initially, but at 20 days tumors were evident and treatment began. LVCN and VCN were administered twice weekly via IV injection (100µg per dose) for 5 weeks. LVCN displayed ~81% inhibition of tumor growth compared to VCN, PBS or empty liposomes. Our findings provide strong support for the effectiveness of LVCN as an inhibitor of PC growth and metastases. Citation Format: Francis S. Markland, Stephen Swenson, Radu Minea, Jacek Pinski. A novel integrin-targeted therapeutic agent for prostate cancer [abstract]. In: Proceedings of the AACR Virtual Special Conference on the Evolving Tumor Microenvironment in Cancer Progression: Mechanisms and Emerging Therapeutic Opportunities; in association with the Tumor Microenvironment (TME) Working Group; 2021 Jan 11-12. Philadelphia (PA): AACR; Cancer Res 2021;81(5 Suppl):Abstract nr PO030.

Pro-Fibrotic Phenotype in a Patient with Segmental Stiff Skin Syndrome via TGF-β Signaling Overactivation

Transforming growth factor β (TGF-β) superfamily signaling pathways are ubiquitous and essential for several cellular and physiological processes. The overexpression of TGF-β results in excessive fibrosis in multiple human disorders. Among them, stiff skin syndrome (SSS) is an ultrarare and untreatable condition characterized by the progressive thickening and hardening of the dermis, and acquired joint limitations. SSS is distinct in a widespread form, caused by recurrent germline variants of FBN1 encoding a key molecule of the TGF-β signaling, and a segmental form with unknown molecular basis. Here, we report a 12-year-old female with segmental SSS, affecting the right upper limb with acquired thickening of the dermis evident at the magnetic resonance imaging, and progressive limitation of the elbow and shoulder. To better explore the molecular and cellular mechanisms that drive segmental SSS, several functional studies on patient’s fibroblasts were employed. We hypothesized an impairment of TGF-β signaling and, consequently, a dysregulation of the associated downstream signaling. Lesional fibroblast studies showed a higher phosphorylation level of extracellular signal-regulated kinase 1/2 (ERK1/2), increased levels of nuclear factor-kB (NFkB), and a nuclear accumulation of phosphorylated Smad2 via Western blot and microscopy analyses. Quantitative PCR expression analysis of genes encoding key extracellular matrix proteins revealed increased levels of COL1A1, COL3A1, AGT, LTBP and ITGB1, while zymography assay reported a reduced metalloproteinase 2 enzymatic activity. In vitro exposure of patient’s fibroblasts to losartan led to the partial restoration of normal transforming growth factor β (TGF-β) marker protein levels. Taken together, these data demonstrate that in our patient, segmental SSS is characterized by the overactivation of multiple TGF-β signaling pathways, which likely results in altered extracellular matrix composition and fibroblast homeostasis. Our results for the first time reported that aberrant TGF-β signaling may drive the pathogenesis of segmental SSS and might open the way to novel therapeutic approaches.

Mass Spectrometry Reveals α-2-HS-Glycoprotein as a Key Early Extracellular Matrix Protein for Conjunctival Cells.

PurposeTo determine the composition of extracellular matrix (ECM) proteins secreted by a conjunctival epithelial cell line and to identify components that aid conjunctival epithelial cell culture.MethodsHuman conjunctival epithelial cell line (HCjE-Gi) cells were cultured in serum-free media and their ECM isolated using ammonium hydroxide. Growth characteristics were evaluated for fresh HCjE-Gi cells plated onto ECMs obtained from 3- to 28-day cell cultures. Mass spectrometry was used to characterize the ECM composition over 42 culture days. Cell adhesion and growth on pre-adsorbed fibronectin and α-2-HS-glycoprotein (α-2-HS-GP) were investigated.ResultsDay 3 ECM provided the best substrate for cell growth compared to ECM obtained from 5- to 28-day cell cultures. Mass spectrometry identified a predominantly laminin 332 matrix throughout the time course, with progressive changes to matrix composition over time: proportional decreases in matrix-bound growth factors and increases in proteases. Fibronectin and α-2-HS-GP were 5- and 200-fold enriched as a proportion of the early ECM relative to the late ECM, respectively. Experiments on these proteins in isolation demonstrated that fibronectin supported rapid cell adhesion, whereas fibronectin and α-2-HS-GP both supported enhanced cell growth compared to tissue culture polystyrene.ConclusionsThese data reveal α-2-HS-GP as a candidate protein to enhance the growth of conjunctival epithelial cells and raise the possibility of exploiting these findings for targeted improvement to synthetic tissue engineered conjunctival substrates.

Increased osteopontin expression in endometrial carcinoma is associated with better survival outcome

Osteopontin (OPN) is a key extracellular matrix protein that is involved in cancer progression. The aim of the current study is to investigate the relation of OPN immunostaining in endometrial carcinoma with clinicopathological parameters. Archival 71 endometrial carcinomas and 30 non-neoplastic endometrial tissues were obtained from the Department of Pathology at King Abdulaziz University Jeddah, Saudi Arabia. Tissue microarrays were constructed. Tissue sections were stained using anti-human OPN monoclonal antibody. Immunostaining results were recorded and analysed. In non-neoplastic endometrial tissues, high (increased) OPN immunostaining was observed in 100%. In endometrial carcinoma, high (increased) OPN immunostaining was seen in 64.8% of cases. High (increased) OPN immunostaining was more frequent in non-neoplastic tissues than in endometrial carcinoma (p < 0.001). OPN immunostaining showed no association with histological type, FIGO tumour grade, tumour size, myometrial invasion, lymphovascular invasion, surgical resection margin or lymph node metastasis. On the other hand, high (increased) OPN immunostaining was associated with better overall survival [Log Rank (Mantel-Cox) = 4.385, p = 0.003]. In endometrial carcinoma, immunohistochemical staining of OPN could be a helpful tool in the prediction survival pattern. OPN immunostaining showed no association with most clinicopathological features. Further investigations both clinical and molecular are needed to explore the downstream of OPN in endometrial carcinoma.

Involvement of Transcription Factor 21 in the Pathogenesis of Fibrosis in Endometriosis

Repeated tissue injury and repair and fibrosis play a pivotal role in endometriosis. Fibrotic tissue consists of extracellular matrix proteins, regulated by transcriptional factors promoting cell proliferation and survival. Periostin is one of the putative key extracellular matrix proteins. This study aimed to determine whether transcription factor 21 (TCF21) is involved in the development of endometriosis as an upstream regulatory gene of periostin. Formalin-fixed, paraffin-embedded tissue samples [normal endometrium of women without endometriosis; eutopic endometrium of women with endometriosis; ovarian endometriosis (OE); and deep infiltrating endometriosis (DIE)] and respective cells were analyzed. Basal, transiently stimulated, and knocked down periostin and TCF21 concentrations in stromal cells of women with or without endometriosis were examined. Periostin and TCF21 expressions were undetected in normal endometrium of women without endometriosis, weakly positive in eutopic endometrium of women with endometriosis, moderately positive in OE, and strongly positive in DIE. Type 2 helper T-cell cytokines (IL-4, IL-13, and transforming growth factor-β1) increased the mRNA expression of periostin and TCF21. These cytokines, periostin, and TCF21 colocalized in the stroma of OE and DIE. siRNA against human TCF21 gene suppressed periostin expression. Transfection of TCF21 plasmid vector into stromal cells of women without endometriosis, which originally expressed neither periostin nor TCF21, resulted in TCF21 and periostin expression. TCF21 and periostin are involved in the regulation of fibrosis in endometriosis. TCF21 may be a promising therapeutic target and biomarker in endometriosis.

Prognostic value of Osteopontin (SPP1) in colorectal carcinoma requires a personalized molecular approach

Stratification of colorectal cancer for better management and tangible clinical outcomes is lacking in clinical practice. To reach this goal, the identification of reliable biomarker(s) is a prerequisite to deliver personalized colorectal cancer theranostics. Osteopontin (SPP1) is a key extracellular matrix protein involved in several pathophysiological processes including cancer progression and metastasis. However, the exact molecular mechanisms regulating its expression, localization, and molecular functions in cancer are still poorly understood. This study was designed to investigate the SPP1 expression profiles in Saudi colorectal cancer patients, and to assess its prognostic value. Hundred thirty-four (134) archival paraffin blocks of colorectal cancer were collected from King Abdulaziz University Hospital, Saudi Arabia. Tissue microarrays were constructed, and automated immunohistochemistry was performed to evaluate SPP1 protein expression patterns in colorectal cancer. About 20% and 23% of our colorectal cancer samples showed high SPP1 cytoplasmic and nuclear expression patterns, respectively. Cytoplasmic SPP1 did not correlate with age, gender, tumor size, and location. However, significant correlations were observed with tumor grade (p = 0.008), tumor invasion (p = 0.01), and distant metastasis (p = 0.04). Kaplan-Meier survival analysis showed a significantly lower recurrence rate in patients with higher SPP1 cytoplasmic expression (p = 0.05). At multivariate analysis, high SPP1 cytoplasmic expression was an independent favorable prognostic marker (p = 0.02). However, nuclear SPP1 expression did not show any prognostic value (p = 0.712). Our results showed a particular SPP1 prognostic relevance that is not in line with most colorectal cancer previous studies that may be attributed to the molecular pathophysiology of our colorectal cancer cohort. Saudi Arabia has both specific genomic makeup and particular environment that could lead to distinctive molecular roots of cancer. SPP1 has several isoforms, tissue localizations and molecular functions, signaling pathways, and downstream molecular functions. Therefore, a more individualized approach for CRC studies and particularly SPP1 prognosis outcomes' assessment is highly recommended toward precision oncology.