Degradation Of Extracellular Matrix Proteins Research Articles

Tryptophan photo-product FICZ upregulates AHR/MEK/ERK-mediated MMP1 expression: Implications in anti-fibrotic phototherapy

BackgroundScleroderma is caused by aberrant transforming growth factor-ß signaling. The degradation of extracellular matrix proteins is regulated by matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs). Ultraviolet (UV) radiation has been a therapy for scleroderma. 6-Formylindolo[3,2-b]carbazole (FICZ), an endogenous aryl hydrocarbon receptor (AHR) ligand, is a tryptophan metabolite generated by UV exposure. Nonetheless, whether FICZ regulates MMPs and TIMPs has not been investigated. ObjectiveTo elucidate the regulatory roles of FICZ in the expression of MMPs and TIMPs in normal human dermal fibroblasts (NHDFs). MethodsQuantitative real-time polymerase chain reaction was performed to determine the expression of MMPs or TIMPs in the NHDFs treated with FICZ or UVB. The MMPs levels were measured by enzyme-linked immunosorbent assay. The actions of FICZ on MMPs were analyzed using AHR-knockdown NHDFs or selective inhibitors of mitogen-activated protein kinases (MAPKs). Microtubule-associated protein kinase (MEK) and extracellular signal-regulated kinase (ERK) phosphorylation was examined by western blotting. ResultsUVB increased the mRNA and protein levels of MMP1 and MMP3 in NHDFs, while FICZ upregulated those of MMP1, but not MMP3. The effects of FICZ on TIMPs were negligible. FICZ increased MMP1 expression in an AHR-dependent manner. The FICZ-induced MMP1 upregulation was ameliorated with MEK/ERK inhibitors, whereas the effects of UVB were canceled with c-Jun N-terminal kinase (JNK) and p38-MAPK as well as MEK/ERK inhibitors. FICZ-induced ERK phosphorylation is dependent on AHR. ConclusionFICZ contributes to the UV-mediated anti-fibrotic effects via the AHR/MEK/ERK signal pathway in NHDFs. FICZ is a potential therapeutic agent for scleroderma.

Cysteine protease cathepsins in cardiovascular disease: from basic research to clinical trials.

Cysteine protease cathepsins have traditionally been considered as lysosome-restricted proteases that mediate proteolysis of unwanted proteins. However, studies from the past decade demonstrate that these proteases are localized not only in acidic compartments (endosomes and lysosomes), where they participate in intracellular protein degradation, but also in the extracellular milieu, plasma membrane, cytosol, nucleus, and nuclear membrane, where they mediate extracellular matrix protein degradation, cell signalling, and protein processing and trafficking through the plasma and nuclear membranes and between intracellular organelles. Studies in experimental disease models and on cathepsin-selective inhibitors, as well as plasma and tissue biomarker data from animal models and humans, have verified the participation of cysteinyl cathepsins in the pathogenesis of many cardiovascular diseases, including atherosclerosis, myocardial infarction, cardiac hypertrophy, cardiomyopathy, abdominal aortic aneurysms, and hypertension. Clinical trials of cathepsin inhibitors in chronic inflammatory diseases suggest the utility of these inhibitors for the treatment of cardiovascular diseases and associated complications. Moreover, development of cell transfer technologies that enable ex vivo cell treatment with cathepsin inhibitors might limit the unwanted systemic effects of cathepsin inhibition and provide new avenues for targeting cysteinyl cathepsins. In this Review, we summarize the available evidence implicating cysteinyl cathepsins in the pathogenesis of cardiovascular diseases, discuss their potential as biomarkers of disease progression, and explore the potential of cathepsin inhibitors for the treatment of cardiovascular diseases.

Colocalization of Galectin-3 With CD147 Is Associated With Increased Gelatinolytic Activity in Ulcerating Human Corneas.

PurposeGalectin-3 is a carbohydrate-binding protein known to promote expression of matrix metalloproteinases, a hallmark of ulceration, through interaction with the extracellular matrix metalloproteinase inducer CD147. The aim of this study was to investigate the distribution of galectin-3 in corneas of patients with ulcerative keratitis and to determine its relationship to CD147 and the presence of gelatinolytic activity.MethodsThis was an observational case series involving donor tissue from 13 patients with active corneal ulceration and 6 control corneas. Fixed-frozen sections of the corneas were processed to localize galectin-3 and CD147 by immunofluorescence microscopy. Gelatinolytic activity was detected by in situ zymography.ResultsTissue from patients with active corneal ulceration showed a greater galectin-3 immunoreactivity in basal epithelia and stroma compared with controls. Immunofluorescence grading scores revealed increased colocalization of galectin-3 and CD147 in corneal ulcers at the epithelial–stromal junction and within fibroblasts. Quantitative analysis using the Manders' colocalization coefficient demonstrated significant overlap in corneas from patients with ulcerative keratitis (M1 = 0.29; M2 = 0.22) as opposed to control corneas (M1 = 0.01, P < 0.01; M2 = 0.02, P < 0.05). In these experiments, there was a significant positive correlation between the degree of galectin-3 and CD147 colocalization and the presence of gelatinolytic activity.ConclusionsOur results indicate that concomitant stimulation and colocalization of galectin-3 with CD147 are associated with increased gelatinolytic activity in the actively ulcerating human cornea and suggest a mechanism by which galectin-3 may contribute to the degradation of extracellular matrix proteins during ulceration.

Redox Imbalance in Intestinal Fibrosis: Beware of the TGFβ-1, ROS, and Nrf2 Connection

Intestinal fibrosis, a common complication of inflammatory bowel diseases, becomes clinically apparent in ~40% of patients with Crohn's disease and ~5% of those with ulcerative colitis. Fibrosis, a consequence of local chronic inflammation, is characterized by excessive deposition of extracellular matrix (ECM) proteins by activated myofibroblasts, which are modulated by pro-fibrotic and anti-fibrotic factors. Fibrosis depends on the balance between production and degradation of ECM proteins. Although the transforming growth factor (TGF)-β1/Smad pathway is the major driving force of fibrosis, several pro-fibrogenic and anti-fibrogenic endogenous factors appear to interact directly with this pathway such as reactive oxygen species (ROS) and nuclear factor-erythroid 2-related factor 2 (Nrf2), which are connected with TGF-β1 during fibrosis development in several organs, including the intestine. Nrf2 is a ubiquitous master transcription factor that upregulates the expression of antioxidant enzymes and cytoprotective proteins mediated by antioxidant response elements (AREs). Here, I describe and discuss the links among TGF-β1, ROS, and Nrf2-AREs in the pathogenesis of intestinal fibrosis.

Matrix Metalloproteinases, Vascular Remodeling, and Vascular Disease.

Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases that degrade various proteins in the extracellular matrix (ECM). Typically, MMPs have a propeptide sequence, a catalytic metalloproteinase domain with catalytic zinc, a hinge region or linker peptide, and a hemopexin domain. MMPs are commonly classified on the basis of their substrates and the organization of their structural domains into collagenases, gelatinases, stromelysins, matrilysins, membrane-type (MT)-MMPs, and other MMPs. MMPs are secreted by many cells including fibroblasts, vascular smooth muscle (VSM), and leukocytes. MMPs are regulated at the level of mRNA expression and by activation through removal of the propeptide domain from their latent zymogen form. MMPs are often secreted in an inactive proMMP form, which is cleaved to the active form by various proteinases including other MMPs. MMPs degrade various protein substrates in ECM including collagen and elastin. MMPs could also influence endothelial cell function as well as VSM cell migration, proliferation, Ca2+ signaling, and contraction. MMPs play a role in vascular tissue remodeling during various biological processes such as angiogenesis, embryogenesis, morphogenesis, and wound repair. Alterations in specific MMPs could influence arterial remodeling and lead to various pathological disorders such as hypertension, preeclampsia, atherosclerosis, aneurysm formation, as well as excessive venous dilation and lower extremity venous disease. MMPs are often regulated by endogenous tissue inhibitors of metalloproteinases (TIMPs), and the MMP/TIMP ratio often determines the extent of ECM protein degradation and tissue remodeling. MMPs may serve as biomarkers and potential therapeutic targets for certain vascular disorders.

Abstract 1327: CD147 contributes to extracellular matrix remodeling and degradation

Abstract Chronic obstructive pulmonary disease (COPD) is an incurable, progressive lung disease characterized by shortness and difficulty in breathing. Patients with COPD are at higher risk of developing lung cancer and often are associated with poor outcome of lung cancer diagnosis and treatment. Extracellular matrix (ECM) remodeling and degradation is one of the common hallmarks between cancer and COPD. It contributes to degradation of air sacs (emphysema) or small airways (obstructive bronchiolitis). It is also involved in cancer initiation and progression to assist tumor expansion and cancer cell migration. In this study, we analyzed lung tissue and primary alveolar type II (ATII) cells isolated from patients with emphysema and control organ donors. ATII cells secrete and store pulmonary surfactant and restore the epithelium after damage. We performed RNA sequencing in ATII cells to identify dysregulated proteins, which are involved in ECM degradation in emphysema. To further study the mechanism involved in the ECM degradation in this disease, we analyzed the expression of selected proteins and we focused on the role of extracellular matrix metalloproteinase inducer (CD147). CD147 is a cell membrane protein involved in inducing the production of extracellular matrix metalloproteinases (MMPs). First, we found that cells isolated from patients with emphysema have higher expression of CD147 in ATII cells in comparison with controls as detected by western blotting and RT-PCR. This may explain high ECM degradation in this disease. Second, we observed higher MMPs levels in plasma obtained from individuals with this disease. Third, we found significantly higher expression of cathepsin B in ATII cells isolated from emphysema in comparison with controls. Cathepsin B is an enzyme that facilitates a direct degradation of ECM proteins and activate other proteases capable of degrading ECM. Fourth, our data indicate that CD147 interacts with cathepsin B, which may lead to the activation of MMPs and emphysema progression. In summary, our results show for the first time the important role of CD147 in emphysema development. Moreover, we found that cathepsin B may contribute to CD147-mediated disease progression. Further studies will elucidate its role in lung cancer development in patients with emphysema. Note: This abstract was not presented at the meeting. Citation Format: Tiffany Tan, Beata Kosmider, Nathaniel Marchetti, Sudhir Bolla, Chenna Mandapati, Gerard Criner, Karim Bahmed. CD147 contributes to extracellular matrix remodeling and degradation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1327. doi:10.1158/1538-7445.AM2017-1327

The role of metalloproteinases in endometrial remodelling during menstrual cycle.

Endometrium is the only tissue in the human body subject to cyclic transformations under the influence of ovarian steroid hormones. As estradiol and progesterone balance throughout the physiological menstrual cycle changes, so does the expression of metalloproteinases (MMPs). These endopeptides are responsible for keeping the balance between the process of synthesis and degradation of extracellular matrix proteins. Thus, MMP's take part in sustaining physiological stability of the endometrium. A number of MMPs found in the endometrial tissue and their activity is related to menstrual cycle phase. This paper is an up-to-date review of literature of Medline database. The search was conducted for key words including "matrix metalloproteinases", "MMPs", "TIMPs" and "tissue inhibitors of metalloproteinases". Over 1092 publications regarding interdependence and interplay between ovarian hormones and the role of various MMPs and their inhibitors in normal endometrial remodelling and in pathological conditions were analysed and critically reviewed.

Role of transforming growth factor β‑1 in the pathogenesis of pelvic organ prolapse: A potential therapeutic target.

The present study aimed to reveal the metabolic alterations of the extracellular matrix (ECM) in uterosacral ligament (USL) with pelvic organ prolapse (POP) and to explore the role of transforming growth factor-β1 (TGF-β1) in pathogenesis of POP. For this purpse, 60 participants who underwent hysterectomy for benign indications were enrolled, 30 of which had symptomatic POP (grade II, III or IV) and composed the POP group, and the other 30 had asymptomatic POP (grade I or less) and served as the controls. Collagen fibers, elastin, matrix metalloproteinase (MMP)-2/9, tissue inhibitor of matrix metalloproteinases (TIMP)-2 and TGF-β1 were examined by Masson's trichrome staining, immunohistochemistry and RT-qPCR using USL biopsies. In vitro, human USL fibroblasts (hUSLFs) were primary cultured, pre-treated with recombinant TGF-β1 (0, 5, or 10 ng/ml) and then subjected to cyclic mechanical stretching (CMS; 0 or 5,333 με strain). Changes in the expression levels of collagen type I/III, elastin, TIMP-2, MMP-2/9 and Smad were detected. Our results revealed that at the tissue level, the expression of collagen fibers, elastin, TIMP-2 and TGF-β1 was significantly reduced in the POP group, while the activities of MMP-2/9 were significantly upregulated, compared with the control group. Statistical analysis indicated that the mRNA expression of TGF-β1 inversely correlated with the severity of POP partially. Our in vitro experimental data demonstrated that a CMS of 5333 με strain promoted the degradation of ECM proteins, inhibited the synthesis of TIMP-2, and upregulated the proteolytic activities of MMP-2/9. Pre-treatment with TGF-β1 attenuated the loss of ECM by stimulating the synthesis of TIMP-2 and inhibiting the activities of MMP-2/9 through the TGF-β1/Smad3 signaling pathway. On the whole, our data indicate that the reduced anabolism and increased catabolism of ECM proteins in USL are the pathological characteristics of POP. TGF-β1 not only has a specific value in predicting the severity of POP, but should also be considered as a novel therapeutic target for POP.

Dencichine ameliorates kidney injury in induced type II diabetic nephropathy via the TGF-β/Smad signalling pathway

Diabetic nephropathy (DN), a common complication associated with both type I and type II diabetes mellitus (DM), is a major cause of chronic nephropathy and a common cause of end-stage renal diseases (ESRD) throughout the world. This study is aimed to determine whether dencichine (De) can ameliorate renal damage in high-glucose-and-fat diet combined STZ (streptozocin) induced DN in type II DM rats and to investigate the potential underlying mechanisms. Markers of metabolism, diabetes, and renal function, and levels of extracellular matrix (ECM) collagen I (Col I), collagen IV (Col IV), fibronectin (FN) and laminin (LN), and of proteins in the TGF-β/Smad pathway were analysed through RT-PCR, western blot, immunofluorescence and immunohistochemistry. The results show that De significantly alleviates metabolism disorder, improved renal function, relieved pathological alterations in the glomerulus of DN rats, decreased ECM deposition and increased the ratio of matrix metalloproteinase (MMP)-9 to tissue inhibitor of metalloproteinase (TIMP)-1 both in vivo and in vitro. Moreover, De negatively regulated TGF-β/Smad signalling pathway and increased the expression of Smad7, an endogenic inhibitory Smad located downstream of the signalling pathway. In conclusion, we provide experimental evidence indicating that the renoprotective effect of De could significantly prevent the progression of DN possibly attribute to down-regulation of the TGF-β/Smad pathway and rebalance the deposition and degradation of ECM proteins.

Abstract 624: Accumulation of Advanced Glycation End Products is Associated With Structural Degeneration of Bioprosthetic Heart Valves

Introduction: Bioprosthetic heart valves (BHV) are widely used but frequently limited by structural valve degeneration (SVD), necessitating re-operation. Calcification is by far the best-studied SVD mechanism, but recent studies suggest that oxidative stress contributes to SVD. Advanced glycation end products (AGEs), formed by the ligation of sugar derivatives to proteins under oxidative conditions, mediate tissue degeneration in cardiovascular diseases. AGEs effect tissue damage through cross-linking and degradation of extracellular matrix proteins including collagen, a major structural component of BHV, as well as through exacerbation of inflammatory cell stimulation. Hypothesis: We hypothesize that AGEs accumulate in BHVs and are associated with oxidative stress-based SVD Methods: We performed immunohistochemistry for AGEs and specifically carboxymethyl lysine (CML) on sections of fixed, paraffin-embedded samples of degenerated bioprosthetic heart valves from 7 patients in the Penn Cardiac Bioregistry (4 male, 3 female, ages 40-83) and 4 short-term experimental Melody valve leaflets deployed in branch pulmonary arteries of 3 sheep. We correlated these results with levels of the circulating AGE receptor sRAGE via ELISA for patient BHV explants and with oxidized amino acid levels quantitated by mass spectrometry of di-tyrosine for experimental sheep BHV explants. Results: There was diffuse accumulation of AGEs in both clinical SVD and sheep explants of BHV. Immunohistochemistry reveals clear AGE and CML staining in all tested valves versus minimal to absent staining in unimplanted control samples. Staining intensity qualitatively correlated with overall di-tyrosine accumulation as well as sRAGE levels that were elevated in BHV patients. Notably, local staining for AGE in BHV is intensified in areas of calcification, thickening, and apparent inflammatory infiltration as well as in areas with structural damage. Conclusions: Extensive AGE accumulation was observed in both BHV explanted for SVD and sheep explants compared to controls, supporting the view that AGEs are associated with SVD pathophysiology. The association of AGE accumulation with di-tyrosine in BHV suggests that oxidative stress is a major mechanism of BHV SVD.

Distribution of cathepsin L in human umbilical cord tissues.

The extracellular matrix components show specific distribution patterns within various structures of the umbilical cord, among which Wharton's jelly is especially collagen-rich tissue. Cathepsin L is a potent cysteine protease engaged in degradation of extracellular matrix proteins, including collagens. We evaluated the activity and expression of cathepsin L, and the inhibitory effect of cysteine protease inhibitors in the umbilical cord arteries, vein and Wharton's jelly. Cathepsin L activity and anti-papain inhibitory effect of cysteine protease inhibitors were quantified in extracts of separated umbilical cord tissues using fluorogenic substrates. The results were calculated per DNA content. The enzyme expression was assessed by Western immunoblotting. The active cathepsin L activity (without activation by pepsin digestion), its percentage in the total activity (after pepsin activation), and the expression of the mature single-chain enzyme were the lowest in the umbilical cord arteries and the highest in Wharton's jelly. The effect of cysteine protease inhibitors showed similar distribution as in the case of the active enzyme, being the highest in Wharton's jelly. Distribution of the activity and expression of mature cathepsin L within the umbilical cord probably results from distinctions in the proenzyme activation process. Differences in the action of cysteine protease inhibitors can partly restrict divergences in the enzyme activity that could reflect its expression alone. Differential enzyme action seems to contribute to tissue-specific collagen turnover within the umbilical cord cells, especially those of Wharton's jelly.

Mast cells as the strength of the inflammatory process.

The inflammatory process is a complex host defence mechanism aimed at the elimination of deleterious factors disturbing homeostasis. Inflammation consists of several interdependent stages controlled by a wide range of mediators. Those include acute phase proteins, heat shock proteins, complement components, biogenic amines, cytokines, lipid-derived mediators, reactive oxygen species, nitric oxide, proteolytic enzymes, and kinins. Due to the strategic location in the body, mast cells play a protective role in the inflammatory process, through its initiation, amplification, and resolution. Mast cells degranulate and/or newly produce, and release various mediators classified into three groups: preformed mediators, de novo synthesised lipid mediators, and newly synthesised cytokines. Those mediators have an impact on different processes occurring during inflammation, inter alia, they influence blood vessels leading to dilation, enhanced adhesion molecule expression, and increased permeability. Furthermore, mast cell mediators play a pivotal role in inflammatory cell chemotaxis, degradation of extracellular matrix proteins, impact on stationery cells and resolution of inflammation. The release of mast cell mediators and their actions constitute a highly complex and still not fully understood mechanism, which warrants further studies of the action of mast cells in inflammation. This review will focus on the current knowledge concerning the broad role of mast cells in the inflammatory process.

Matrix Metalloproteinases in Remodeling of Lower Extremity Veins and Chronic Venous Disease.

The veins of the lower extremity are equipped with efficient wall, contractile vascular smooth muscle (VSM), and competent valves in order to withstand the high venous hydrostatic pressure in the lower limb and allow unidirectional movement of deoxygenated blood toward the heart. The vein wall structure and function are in part regulated by matrix metalloproteinases (MMPs). MMPs are zinc-dependent endopeptidases that are secreted as inactive pro-MMPs by different cells in the venous wall including fibroblasts, VSM, and leukocytes. Pro-MMPs are activated by other MMPs, proteinases, and other endogenous and exogenous activators. MMPs degrade various extracellular matrix (ECM) proteins including collagen and elastin, and could affect other cellular processes including endothelium-mediated dilation, VSM cell migration, and proliferation as well as modulation of Ca2+ signaling and contraction in VSM. It is thought that increased lower limb venous hydrostatic pressure increases hypoxia-inducible factors and other MMP inducers such as extracellular matrix metalloproteinase inducer, leading to increased MMP expression/activity, ECM protein degradation, vein wall relaxation, and venous dilation. Vein wall inflammation and leukocyte infiltration cause additional increases in MMPs, and further vein wall dilation and valve degradation, that could lead to chronic venous disease and varicose veins (VVs). VVs are often presented as vein wall dilation and tortuosity, incompetent venous valves, and venous reflux. Different regions of VVs show different MMP levels and ECM proteins with atrophic regions showing high MMP levels/activity and little ECM compared to hypertrophic regions with little or inactive MMPs and abundant ECM. Treatment of VVs includes compression stockings, venotonics, sclerotherapy, or surgical removal. However, these approaches do not treat the cause of VVs, and other lines of treatment may be needed. Modulation of endogenous tissue inhibitors of metalloproteinases (TIMPs), and exogenous synthetic MMP inhibitors may provide new approaches in the management of VVs.

Serum metalloproteinase 9 levels increase after generalized tonic-clonic seizures

Metalloproteinase 9 (MMP9) is a member of a family of enzymes that mediate the degradation of extracellular matrix proteins, and is especially involved in blood–brain barrier maintenance. Increased levels of MMP9 have been observed in many neurological disorders, including epilepsy, suggesting it may be involved in the pathogenesis of seizures. We investigated changes in MMP9 serum levels after acute seizures in epilepsy patients. Concentrations of MMP9 in serum were measured by ELISA in 43 patients 1–3, 24, and 72h after generalized tonic-clonic seizure and once in participants of the control group. MMP9 levels were significantly increased 1–3 and 24h after seizure and decreased to control levels 72h after seizure. Our results suggest that MMP9 is released after or just before seizure; however, further studies are needed to resolve the consequences of the observed MMP9 increase.

LRP-1 Pathway Targeted Inhibition of Vascular Abnormalities in the Retina of Diabetic Mice

ABSTRACTPurpose: The cell surface LDL (low-density lipoprotein) receptor-related protein-1 (LRP-1) is important for lipid transport and several cell signaling processes. Human apolipoprotein E (apoE) is a ligand of LRP-1. We previously reported that a short peptide (apoEdp) mimicking the LRP-1 binding region of apoE prevents hyperglycemia-induced retinal endothelial cell dysfunction in vitro. The in-vivo outcome of apoE-based peptidomimetic inhibition of LRP-1 in the treatment of diabetic retinopathy is unknown.Methods: Six months after streptozotocin induction of diabetes, male C57Bl/6 mice were intravitreally inoculated with apoEdp in a controlled release formulation. On the 15th day post-apoEdp treatment, mouse retinas were harvested to examine (1) blood–retinal–barrier (BRB) permeability by Evans blue dye, inflammatory leukostasis by concanavalin staining of leukocytes and LRP-1 pathway-related protein expression by Western blot analysis and gelatin zymography.Results: Intravitreal apoEdp treatment of diabetic mice significantly reduced Evans blue extravasation and the number of adherent leukocytes in the diabetic mouse retinas. ApoEdp treatment inhibited the expression of extracellular matrix (ECM) degrading proteases heparanase and MMP-2, and restores the BRB tight junction proteins occludin and ZO-1. ApoEdp treatment also inhibited Wnt/β-catenin-related expression of pro-inflammatory molecules ICAM-1, HIF-1α, and VEGF through negative regulation by LRP-1.Conclusion: Intravitreal apoEdp treatment of diabetic mice resulted a significant decrease in retinal vascular abnormalities through downregulation of LRP-1-related ECM protein degradation and Wnt/β-catenin-related pro-angiogenic molecules.

MMP-9 overexpression is associated with intragenic hypermethylation of MMP9 gene in melanoma.

Tumor spreading is associated with the degradation of extracellular matrix proteins, mediated by the overexpression of matrix metalloproteinase 9 (MMP-9). Although, such overexpression was linked to epigenetic promoter methylation, the role of intragenic methylation was not clarified yet. Melanoma was used as tumor model to investigate the relationship between the DNA intragenic methylation of MMP9 gene and MMP-9 overexpression at transcriptional and protein levels. Computational analysis revealed DNA hypermethylation within the intragenic CpG-2 region of MMP9 gene in melanoma samples with high MMP-9 transcript levels. In vitro validation showed that CpG-2 hotspot region was hypermethylated in the A375 melanoma cell line with highest mRNA and protein levels of MMP-9, while low methylation levels were observed in the MEWO cell line where MMP-9 was undetectable. Concordant results were demonstrated in both A2058 and M14 cell lines. This correlation may give further insights on the role of MMP-9 upregulation in melanoma.

Clearance of matrix metalloproteinase-9 is dependent on low-density lipoprotein receptor-related protein-1 expression downregulated by microRNA-205 in human abdominal aortic aneurysm

Low-density lipoprotein receptor-related protein-1 (LRP1) has been suggested to be a crucial regulator in the pathogenesis of abdominal aortic aneurysm (AAA) from previous genome association and animal studies. Our prior study using human aortic samples has further revealed a significant reduction of LRP1 protein expression associated with AAA. However, the downregulation of LRP1 in the pathophysiology of AAA remained unresolved. We hypothesized that LRP1 downregulation may be mediated by microRNA (miR) and that LRP1 may function as a scavenger of matrix metalloproteinase-9 (MMP-9), a well-known protease for degradation of extracellular matrix proteins at the aortic wall for AAA pathogenesis. This study investigated the cause of LRP1 downregulation and its potential effect on AAA pathogenesis. An observational study of LRP1 protein, LRP1 messenger RNA (mRNA), and its three predicted miR candidates (miR-205, miR-338-5p, and miR-545-3p) was first performed in AAA compared with nonaneurysmal tissues from humans, followed by a functional study testing the effect on LRP1 expression of miR-205 overexpression and knockdown in human vascular smooth muscle cells (VSMCs) explant cultured from human abdominal aortic tissues. Lastly, another functional study was performed to test for the clearance of exogenous MMP-9 upon silencing of LRP1 in human VSMCs. From the observational study, significantly higher miR-205 (P< .001) and lower LRP1 protein (P< .001) expressions were found in human AAA tissues compared with nonaneurysmal aortic tissues, and no significant difference in LRP1 mRNA expression was observed. Further statistical analysis showed a significant negative correlation between miR-205 and LRP1 protein expressions (r=-0.65; P< .01). For the functional study, a significant downregulation of LRP1 protein expression was shown in miR-205-overexpressing VSMCs (P< .05), without any alteration in LRP1 mRNA expression. Moreover, a significantly reduced clearance of exogenous MMP-9 was observed in LRP1-silenced VSMCs (P< .05), and this difference in MMP-9 clearance was completely abolished with a pretreatment of anti-LRP1 antibody. Our study revealed the downregulation of LRP1 protein expression may be tightly regulated by miR-205 through translational inhibition in human VSMCs. Also, such LRP1 down-regulation in VSMCs may hinder the removal of pericellular MMP-9, leading to excess MMP-9 remaining in the extracellular matrix. Hence, the integrity of the vascular wall may be disrupted, promoting AAA formation.

The proteolytic profile of human cancer procoagulant suggests that it promotes cancer metastasis at the level of activation rather than degradation.

Proteases are essential for tumour progression and many are over-expressed during this time. The main focus of research was the role of these proteases in degradation of the basement membrane and extracellular matrix (ECM), thereby enabling metastasis to occur. Cancer procoagulant (CP), a protease present in malignant tumours, but not normal tissue, is a known activator of coagulation factor X (FX). The present study investigated the function of CP in cancer progression by focussing on its enzymatic specificity. FX cleavage was confirmed using SDS-PAGE and MALDI-TOF MS and compared to the proteolytic action of CP on ECM proteins, including collagen type IV, laminin and fibronectin. Contrary to previous reports, CP cleaved FX at the conventional activation site (between Arg-52 and Ile-53). Additionally, degradation of FX by CP occurred at a much slower rate than degradation by conventional activators. Complete degradation of the heavy chain of FX was only visible after 24h, while degradation by RVV was complete after 30min, supporting postulations that the procoagulant function of CP may be of secondary importance to its role in cancer progression. Of the ECM proteins tested, only fibronectin was cleaved. The substrate specificity of CP was further investigated by screening synthetic peptide substrates using a novel direct CP assay. The results indicate that CP is not essential for either cancer-associated blood coagulation or the degradation of ECM proteins. Rather, they suggest that this protease may be required for the proteolytic activation of membrane receptors.

Abstract LB-204: Reprogramming inflammatory monocytes to mediate anti-tumor activity in pancreatic carcinoma

Abstract In cancer, increased mobilization of inflammatory monocytes from the bone marrow into the peripheral blood correlates inversely with patient survival. Peripheral blood inflammatory monocytes, which express CCR2, are recruited to tumor tissue by the chemokine CCL2 where they then differentiate into macrophages and support tumor development, growth, and metastasis. While neutralization of CCL2 can block inflammatory monocyte recruitment and inhibit metastasis, this approach has recently been shown to be at risk for lethal outcomes if therapy is interrupted. An alternative approach to inhibiting inflammatory monocyte recruitment to tumors is to reprogram monocytes with anti-tumor activity. Using the KrasG12D/+; Trp53R172H/+; Pdx-1 Cre (KPC) genetically engineered mouse model of pancreatic ductal adenocarcinoma (PDAC), we report that systemic immune activation induced with an agonist CD40 monoclonal antibody can redirect Gr-1+ inflammatory monocytes to infiltrate the tumor microenvironment and degrade tumor-associated fibrosis leading to tumor regression. Extra-tumoral macrophages were found to be necessary for mobilization of inflammatory monocytes from the bone marrow into the peripheral blood. In addition, systemic IFN-γ released in response to anti-CD40 therapy was necessary for reprogramming inflammatory monocytes with anti-tumor activity. Inflammatory monocytes responding to IFN-γ displayed a distinct matrix metalloproteinase gene expression profile necessary for selective degradation of extracellular matrix proteins, including type I collagen and fibronectin, which define fibrosis in PDAC. Therefore, although inflammatory monocytes are commonly associated with pro-tumor activity, our findings demonstrate that they can also be reprogrammed with potent anti-tumor properties. Citation Format: Kristen B. Long, Whitney L. Gladney, Graham M. Tooker, Gregory L. Beatty. Reprogramming inflammatory monocytes to mediate anti-tumor activity in pancreatic carcinoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr LB-204. doi:10.1158/1538-7445.AM2015-LB-204

Abstract 4164: uPA modulates angiogenesis through transcriptional regulation of vascular endothelial growth factor (VEGF) receptors VEGFR1 and VEGFR2

Abstract The urokinase-type plasminogen activator (uPA) system has multifunctional roles in neoplastic grows and metastasis, affecting cancer cell proliferation, adhesion, migration and survival, and tumor angiogenesis. uPA mediates tumor angiogenesis and vascular permeability through proteolytic degradation of extracellular matrix proteins, activation of release of growth factors and by intracellular signaling initiated upon its binding to the uPA receptor (CD87) and others. In accord with this, we observed that VEGF-induced endothelial cell (EC) proliferation is dependent on uPA; ECs isolated from uPA knockout mice (uPA-/- ECs) show less proliferation in response to VEGF than their wild type counterparts or than uPA-/- ECs in which expression of wild type uPA has been restored using lentiviral transfection. We reported previously that uPA is transported from cell surface to nuclei through a mechanism that requires its kringle domain, and that intranuclear uPA modulates gene transcription by binding to a subset of transcription factors (1, 2). Here, we show that uPA regulates angiogenesis in part through this novel mechanism. Wild type single-chain uPA (WT-scuPA) translocates to the nuclei of ECs, but not a kringle-deficient uPA variant (ΔK-scuPA) incapable of nuclear transport(1). Translocation of uPA is accompanied by increased expression of cell surface VEGF receptor 1 (VEGFR1) and VEGF receptor 2 (VEGFR2), whereas ΔK-scuPA had no effect on expression of either receptor. We used a transcription factor protein-protein microarray to identify the intranuclear target responsible for regulating receptor expression. We report that uPA binds hematopoietically expressed homeobox transcription factor (HHEX), also referred to as proline-rich homeobox TF (PRH), which has been identified by us previously as a transcriptional repressor of vegf, vegfr1 and vegfr2 promoters(3). uPA directly binds to HHEX/PRH, interferes with its binding to the target DNA sequence, and de-represses transcription of vegfr1 and vegfr2 genes. These studies identify a novel mechanism underlying the pro-angiogenic effects of VEGF through uPA binding to HHEX/PRH leading to de-repression of vegfr1 and vegfr2 gene transcription and thereby suggest that interruption of this pathway might provide a new approach to mitigate tumor angiogenesis. References. 1. Stepanova V, Lebedeva T, Kuo A, Yarovoi S, Tkachuk S, Zaitsev S, Bdeir Kh, Dumler I, Marks M.S., Parfyonova Ye, Tkachuk VA, Higazi A.-A., Cines D.B. (2008) Blood 112(1): 100-110. 2. Asuthkar S, Stepanova V, Lebedeva T, Holterman AL, Estes N, Cines DB, Rao JS, Gondi CS. (2013) Mol Biol Cell. 24(17):2620-32. 3. Noy P, Williams H, Sawasdichai A, Gaston K, Jayaraman PS. Mol Cell Biol. (2010) 30(9):2120-34. Note: This abstract was not presented at the meeting. Citation Format: Victoria Stepanova, Padma Sheela Jayaraman, Sergei V. Zaitsev, Tatiana Lebedeva, Rachael M. Kershaw, Douglas B. Cines. uPA modulates angiogenesis through transcriptional regulation of vascular endothelial growth factor (VEGF) receptors VEGFR1 and VEGFR2. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4164. doi:10.1158/1538-7445.AM2015-4164