Academic literature on the topic 'Matrix remodeling enzyme LOXL2'

Abstract Sprouting angiogenesis is associated with extensive extracellular matrix (ECM) remodeling. The molecular mechanisms involved in building the vascular microenvironment and its impact on capillary formation remain elusive. We therefore performed a proteomic analysis of ECM from endothelial cells maintained in hypoxia, a major stimulator of angiogenesis. Here, we report the characterization of lysyl oxidase-like protein-2 (LOXL2) as a hypoxia-target expressed in neovessels and accumulated in the endothelial ECM. LOXL2 belongs to the lysyl oxidase family of secreted enzymes involved in ECM crosslinking. Knockdown experiments in Tg(fli1:egfp)y1 zebrafish embryos resulted in lack of intersegmental vessel circulation and demonstrated LOXL2 involvement in proper capillary formation. Further investigation in vitro by loss and gain of function experiments confirmed that LOXL2 was required for tubulogenesis in 3D fibrin gels and demonstrated that this enzyme was required for collagen IV assembly in the ECM. In addition, LOXL2 depletion down-regulated cell migration and proliferation. These data suggest a major role for LOXL2 in the organization of endothelial basal lamina and in the downstream mechanotransductive signaling. Altogether, our study provides the first evidence for the role of LOXL2 in regulating angiogenesis through collagen IV scaffolding.

Lysyl oxidase-like 2 (LOXL2) was initially described as an extracellular enzyme involved in extracellular matrix remodeling. Nevertheless, numerous recent reports have implicated intracellular LOXL2 in a wide variety of processes that impact on gene transcription, development, differentiation, proliferation, migration, cell adhesion, and angiogenesis, suggesting multiple different functions for this protein. In addition, increasing knowledge about LOXL2 points to a role in several types of human cancer. Moreover, LOXL2 is able to induce the epithelial-to-mesenchymal transition (EMT) process—the first step in the metastatic cascade. To uncover the underlying mechanisms of the great variety of functions of intracellular LOXL2, we carried out an analysis of LOXL2’s nuclear interactome. This study reveals the interaction of LOXL2 with numerous RNA-binding proteins (RBPs) involved in several aspects of RNA metabolism. Gene expression profile analysis of cells silenced for LOXL2, combined with in silico identification of RBPs’ targets, points to six RBPs as candidates to be substrates of LOXL2’s action, and that deserve a more mechanistic analysis in the future. The results presented here allow us to hypothesize novel LOXL2 functions that might help to comprehend its multifaceted role in the tumorigenic process.

Abstract Ductal carcinoma is the most commonly diagnosed breast cancer in women, the presence of metastases drops patient five-year survival from 95% to an abysmal 27%. This makes studying the mechanisms that promote metastasis of critical importance. Research shows that the extracellular matrix (ECM) of the tumor microenvironment (TME) plays an important role in invasive ductal carcinoma (IDC) progression and metastasis. Specifically; the density, stiffness, and orientation of collagen I fibers in the stroma all impact IDC motility, invasion, and metastasis. Lysyl oxidase-like 2 (LOXL2) is a secreted enzymatic protein that is implicit in ECM remodeling. By catalyzing an oxidative reaction in peptidyl lysine/hydroxylysine present on collagen I fibers, LOXL2 initiates crosslinking of the fibers. Our previous publication demonstrates that interleukin-6-related pro-inflammatory cytokine signaling, specifically oncostatin M (OSM), led to the overexpression and secretion of the LOXL2 enzyme. This increased the metastatic potential of IDC cells by promoting the crosslinking and alignment of collagen I fibers, which in turn led to increased invasion in 3D collagen I matrices. Thus, we hypothesize that OSM-induced LOXL2 expression, secretion, and subsequent collagen I fiber crosslinking and alignment, leads to an increase in IDC metastasis. In vivo studies utilizing nude athymic mice injected with either MCF7-Luc-EV control or MCF7-Luc-OSM overexpressing cells were performed in conjunction with LOXL2 inhibition using specially designed chow containing either LOXL2 SMI or control. Further analysis of OSM signaling pathways was performed in MCF7 and MDA-MB-468 IDC cells to determine mechanism for OSM induction of LOXL2. Our studies demonstrate that canonical OSM signaling pathways (pERK, pSTAT3, and pAKT) all contribute to LOXL2 expression in MCF7 cells suggesting a possible mediator protein we identified as c-Myc. Furthermore, OSM-induced LOXL2 played a significant role in OSM promoted tumor growth and metastasis as LOXL2 inhibition led to decreased tumor size and far less metastatic lesions. We also analyzed and confirmed a synergistic interaction between OSM and interleukin-1beta (IL-1β) in LOXL2 expression. These results confirm the significance of LOXL2 expression in OSM promoted metastasis and suggests LOXL2 would be an important target for future breast cancer therapies, specifically in patients with elevated levels of OSM. Furthermore, the synergistic interaction between OSM and IL-1β in LOXL2 expression suggests that patients with high levels of both cytokines are at even greater risk of metastasis, making these great markers for determining at risk IDC patients. Citation Format: Simion Dinca, Cody Wolf, Laura Bond, Cheryl Jorcyk. OSM-induced LOXL2 expression hinges on upregulation of c-Myc and promotes tumor growth and metastasis, IL-1beta plays synergistic role in LOXL2 expression. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3645.

Evidence is increasing on the crucial role of the extracellular matrix (ECM) in breast cancer progression, invasion and metastasis with almost all mortality cases owing to metastasis. The epithelial-mesenchymal transition is the first signal of metastasis involving different transcription factors such as Snail, TWIST, and ZEB1. ECM remodeling is a major event promoting cancer invasion and metastasis; where matrix metalloproteinases (MMPs) such as MMP-2, -9, -11, and -14 play vital roles degrading the matrix proteins for cancer spread. The β-D mannuronic acid (MMP inhibitor) has anti-metastatic properties through inhibition of MMP-2, and -9 and could be a potential therapeutic agent. Besides the MMPs, the enzymes such as LOXL2, LOXL4, procollagen lysyl hydroxylase-2, and heparanase also regulate breast cancer progression. The important ECM proteins like integrins (b1-, b5-, and b6- integrins), ECM1 protein, and Hic-5 protein are also actively involved in breast cancer development. The stromal cells such as tumor-associated macrophages (TAMs), cancer-associated fibroblasts (CAFs), and adipocytes also contribute in tumor development through different processes. The TAMs become proangiogenic through secretion of VEGF-A and building vessel network for nourishment and invasion of the tumor mass. The latest developments of ECM involvement in breast cancer progression has been discussed in this review and this study will help researchers in designing future work on breast cancer pathogenesis and developing therapy targeted to the ECM components.

Evidence is increasing on the crucial role of the extracellular matrix (ECM) in breast cancer progression, invasion and metastasis with almost all mortality cases owing to metastasis. The epithelial-mesenchymal transition is the first signal of metastasis involving different transcription factors such as Snail, TWIST, and ZEB1. ECM remodeling is a major event promoting cancer invasion and metastasis; where matrix metalloproteinases (MMPs) such as MMP-2, -9, -11, and -14 play vital roles degrading the matrix proteins for cancer spread. The β-D mannuronic acid (MMP inhibitor) has anti-metastatic properties through inhibition of MMP-2, and -9 and could be a potential therapeutic agent. Besides the MMPs, the enzymes such as LOXL2, LOXL4, procollagen lysyl hydroxylase-2, and heparanase also regulate breast cancer progression. The important ECM proteins like integrins (b1-, b5-, and b6- integrins), ECM1 protein, and Hic-5 protein are also actively involved in breast cancer development. The stromal cells such as tumor-associated macrophages (TAMs), cancer-associated fibroblasts (CAFs), and adipocytes also contribute in tumor development through different processes. The TAMs become proangiogenic through secretion of VEGF-A and building vessel network for nourishment and invasion of the tumor mass. The latest developments of ECM involvement in breast cancer progression has been discussed in this review and this study will help researchers in designing future work on breast cancer pathogenesis and developing therapy targeted to the ECM components.

Abstract Hypertensive cardiac hypertrophy (HCH) is a common cause of heart failure (HF), a major public health problem worldwide. However, the molecular bases of HCH have not been completely elucidated. Neuron-derived orphan receptor-1 (NOR-1) is a nuclear receptor whose role in cardiac remodelling is poorly understood. The aim of the present study was to generate a transgenic mouse over-expressing NOR-1 in the heart (TgNOR-1) and assess the impact of this gain-of-function on HCH. The CAG promoter-driven transgenesis led to viable animals that over-expressed NOR-1 in the heart, mainly in cardiomyocytes and also in cardiofibroblasts. Cardiomyocytes from TgNOR-1 exhibited an enhanced cell surface area and myosin heavy chain 7 (Myh7)/Myh6 expression ratio, and increased cell shortening elicited by electric field stimulation. TgNOR-1 cardiofibroblasts expressed higher levels of myofibroblast markers than wild-type (WT) cells (α 1 skeletal muscle actin (Acta1), transgelin (Sm22α)) and were more prone to synthesise collagen and migrate. TgNOR-1 mice experienced an age-associated remodelling of the left ventricle (LV). Angiotensin II (AngII) induced the cardiac expression of NOR-1, and NOR-1 transgenesis exacerbated AngII-induced cardiac hypertrophy and fibrosis. This effect was associated with the up-regulation of hypertrophic (brain natriuretic peptide (Bnp), Acta1 and Myh7) and fibrotic markers (collagen type I α 1 chain (Col1a1), Pai-1 and lysyl oxidase-like 2 (Loxl2)). NOR-1 transgenesis up-regulated two key genes involved in cardiac hypertrophy (Myh7, encoding for β-myosin heavy chain (β-MHC)) and fibrosis (Loxl2, encoding for the extracellular matrix (ECM) modifying enzyme, Loxl2). Interestigly, in transient transfection assays, NOR-1 drove the transcription of Myh7 and Loxl2 promoters. Our findings suggest that NOR-1 is involved in the transcriptional programme leading to HCH.

Tumor progression is a complex process involving extracellular matrix (ECM) remodeling and stiffening. However, the mechanisms that govern these processes and their roles in tumor progression are still poorly understood. In this study, we performed bioinformatics, immunohistochemical, and biochemical analyses to examine if collagen cross-linking is associated with tumor stage and regional lymph node metastasis (RLNM) in oral squamous cell carcinoma (OSCC). We found that the genes encoding key enzymes for cross-linking are frequently overexpressed in oral, head, and neck cancers. Specifically, the enzymes lysyl hydroxylase 2 (LH2) or lysyl oxidase (LOX) and LOX-like 2 (LOXL2) were significantly upregulated in late-stage tumors and associated with poor patient prognosis. The protein levels of these enzymes in the primary human OSCC were also significantly increased in late-stage tumors and markedly elevated in the RLNM-positive tumors. Notably, while overall LOX/LOXL2-catalyzed collagen cross-links were enriched in late-stage and RLNM-positive tumors, LH2-mediated stable cross-links were significantly increased. To our knowledge, this is the first study to investigate the association of collagen cross-linking and expression of key enzymes regulating this process with OSCC stage. The data indicate a critical role for collagen cross-linking in OSCC tumor progression and metastasis, which may provide insights into development of novel therapeutic strategies to prevent OSCC progression.

Integrin α11, a stromal collagen receptor, promotes tumor growth and metastasis of non-small cell lung cancer (NSCLC) and is associated with the regulation of collagen stiffness in the tumor stroma. We have previously reported that lysyl oxidase like-1 (LOXL1), a matrix cross-linking enzyme, is down-regulated in integrin α11-deficient mice. In the present study, we investigated the relationship between LOXL1 and integrin α11, and the role of LOXL1 in NSCLC tumorigenicity. Our results show that the expression of LOXL1 and integrin α11 was correlated in three lung adenocarcinoma patient datasets and that integrin α11 indeed regulated LOXL1 expression in stromal cells. Using cancer-associated fibroblast (CAF) with either a knockdown or overexpression of LOXL1, we demonstrated a role for LOXL1 in collagen matrix remodeling and collagen fiber alignment in vitro and in vivo in a NSCLC xenograft model. As a consequence of collagen reorganization in NSCLC tumor stroma, we showed that LOXL1 supported tumor growth and progression. Our findings demonstrate that stromal LOXL1, under regulation of integrin α11, is a determinant factor of NSCLC tumorigenesis and may be an interesting target in this disease.

Pterygium is a benign fibrovascular lesion of the bulbar conjunctiva with frequent involvement of the corneal limbus. Its pathogenesis has been mainly attributed to sun exposure to ultraviolet-B radiation. Obtained evidence has shown that it is a complex and multifactorial process which involves multiple mechanisms such as oxidative stress, dysregulation of cell cycle checkpoints, induction of inflammatory mediators and growth factors, angiogenic stimulation, extracellular matrix (ECM) disorders, and, most likely, viruses and hereditary changes. In this review, we aim to collect all authors’ experiences and our own, with respect to the study of fibroelastic ECM of pterygium. Collagen and elastin are intrinsic indicators of physiological and pathological states. Here, we focus on an in-depth analysis of collagen (types I and III), as well as the main constituents of elastic fibers (tropoelastin (TE), fibrillins (FBNs), and fibulins (FBLNs)) and the enzymes (lysyl oxidases (LOXs)) that carry out their assembly or crosslinking. All the studies established that changes in the fibroelastic ECM occur in pterygium, based on the following facts: An increase in the synthesis and deposition of an immature form of collagen type III, which showed the process of tissue remodeling. An increase in protein levels in most of the constituents necessary for the development of elastic fibers, except FBLN4, whose biological roles are critical in the binding of the enzyme LOX, as well as FBN1 for the development of stable elastin. There was gene overexpression of TE, FBN1, FBLN5, and LOXL1, while the expression of LOX and FBLN2 and -4 remained stable. In conclusion, collagen and elastin, as well as several constituents involved in elastic fiber assembly are overexpressed in human pterygium, thus, supporting the hypothesis that there is dysregulation in the synthesis and crosslinking of the fibroelastic component, constituting an important pathogenetic mechanism for the development of the disease.

Vascular stiffening and its sequelae are major causes of morbidity and mortality in the elderly. The increasingly accepted concept of “smooth muscle cell (SMC) stiffness syndrome” along with matrix deposition has emerged in vascular biology to account for the mechanical phenotype of arterial aging, but the molecular targets remain elusive. In this study, using an unbiased proteomic analysis, we identified lysyl oxidase-like 2 (LOXL2) as a critical SMC mediator for age-associated vascular stiffening. We tested the hypothesis that loss of LOXL2 function is protective in aging-associated vascular stiffening. We determined that exogenous and endogenous nitric oxide markedly decreased LOXL2 abundance and activity in the extracellular matrix of isolated SMCs and LOXL2 endothelial cells suppress LOXL2 abundance in the aorta. In a longitudinal study, LOXL2+/− mice were protected from age-associated increase in pulse-wave velocity, an index of vascular stiffening, as occurred in littermate wild-type mice. Using isolated aortic segments, we found that LOXL2 mediates vascular stiffening in aging by promoting SMC stiffness, augmented SMC contractility, and vascular matrix deposition. Together, these studies establish LOXL2 as a nodal point for a new therapeutic approach to treat age-associated vascular stiffening. NEW & NOTEWORTHY Increased central vascular stiffness augments risk of major adverse cardiovascular events. Despite significant advances in understanding the genetic and molecular underpinnings of vascular stiffening, targeted therapy has remained elusive. Here, we show that lysyl oxidase-like 2 (LOXL2) drives vascular stiffening during aging by promoting matrix remodeling and vascular smooth muscle cell stiffening. Reduced LOXL2 expression protects mice from age-associated vascular stiffening and delays the onset of isolated systolic hypertension, a major consequence of stiffening.

Le mélanome cutané est un cancer de la peau agressif, hétérogène et hautement métastatique. Malgré le succès des nouveaux traitements comme les thérapies ciblant la voie oncogénique BRAFV600, et les inhibiteurs des points de contrôle immunitaire, de nombreux patients restent en échec thérapeutique en raison de résistances innées ou acquises dues à des mutations génétiques ou des phénomènes non-génétiques de reprogrammation et plasticité phénotypique. Des études récentes ont identifié des sous-populations cellulaires tumorales qui se distinguent selon leur état de différenciation et leur signature transcriptionnelle. En réponse aux signaux du microenvironnement et aux pressions thérapeutiques, les cellules de mélanome peuvent passer d'un état mélanocytaire à des états dédifférenciés associés à une expression accrue de récepteurs tyrosine kinase (RTK), de marqueurs mésenchymateux ou de cellules souches de la crête neurale. Cette transition a été décrite comme un facteur d'adaptation et de résistance aux thérapies ciblées. La progression tumorale est influencée par les propriétés biochimiques et biophysiques du stroma matriciel environnant. Ainsi, une augmentation des dépôts de collagène et de la réticulation des fibres rigidifie la tumeur, promeut la progression maligne et protège des thérapies. Mon travail s'appuie sur des observations originales de l'équipe selon lesquelles les cellules dédifférenciées produisent une matrice extracellulaire (MEC) abondante riche en lysyl oxidase-like 2, LOXL2, une enzyme de réticulation du collagène également connue pour son implication dans la transition épithéliale-mésenchymateuse du cancer du sein. Son rôle dans la biologie des mélanomes n'est pas connu. Nous avons émis l'hypothèse que la production de LOXL2 par les cellules de mélanome pourrait influencer leurs propriétés mésenchymateuses ainsi que le remodelage matriciel et la rigidité tumorale observés in vivo au cours de la réponse adaptative au traitement.Nous montrons dans un premier temps que LOXL2 est préférentiellement exprimé par les cellules de mélanome dédifférenciées et que son expression est associée à un mauvais pronostic. LOXL2 est induit par la thérapie ciblée ou l'hypoxie, des facteurs connus pour favoriser la transition vers un état dédifférencié, et est régulé par des facteurs de transcription de la plasticité tumorale comme ZEB1. De façon intéressante, l'induction de LOXL2 par la thérapie ciblée est inversée par les inhibiteurs des voies RTK et AKT. Dans un deuxième temps, nous avons étudié la contribution spécifique de LOXL2 dans le phénotype tumoral dédifférencié par des approches perte de fonction. Nous révélons que LOXL2 joue un rôle important dans la formation d'adhésions focales et la morphologie des cellules mésenchymateuses et favorise leur migration, invasion et formation de métastases. Sur le plan mécanistique, une analyse protéomique comparative a permis d'identifier l'inhibiteur de l'activateur du plasminogène 2, PAI-2, un membre de la famille des serpines comme un effecteur potentiel de la migration dépendante de LOXL2. Enfin, mes données indiquent que le ciblage de LOXL2 dans les cellules dédifférenciées et les fibroblastes associés au mélanome réduit leur capacité à contracter une matrice de collagène et à assembler une MEC organisée, ce qui suggère l'implication de LOXL2 dans le dialogue entre cellules de mélanome et matrice tumorale.L'ensemble de mes résultats établit un lien original entre LOXL2, l'hétérogénéité phénotypique des cellules de mélanome et le remodelage matriciel stromal. Notre étude révèle qu'en plus de son rôle dans le remodelage du collagène, LOXL2 joue un rôle pro-invasif « cell autonomous » intrinsèque à la cellule de mélanome. De plus, mon travail améliore notre compréhension des signaux biomécaniques de la MEC qui affectent la plasticité tumorale et l'adaptation aux thérapies et souligne l'intérêt du ciblage de LOXL2 dans le traitement de la maladie métastatique et résistante
Cutaneous melanoma is an aggressive, heterogeneous and highly metastatic skin cancer. Despite successful therapies targeting the BRAFV600E oncogenic pathway or immune checkpoints, many patients relapse and remain in therapeutic failure. Innate or acquired resistances are due to genetic mutations or non-genetic phenotypic reprogramming and plasticity. Recent studies based on single cell RNA-seq analysis of cutaneous melanoma have identified tumor cell subpopulations that are classified according to their differentiation state and transcriptional signature. Upon microenvironment and therapeutic pressures, melanoma cells can switch from a melanocytic state to dedifferentiated states associated with increased expression of tyrosine kinase receptors (RTK) and mesenchymal or neural crest stem cell-like markers. Such adaptive plasticity was described as a driver of resistance to targeted therapies. Tumor progression is influenced by alterations in the biochemical and biophysical properties of the tumor microenvironment. Increased collagen fiber deposition and crosslinking are indeed known to stiffen tumors, promote malignant progression and confer resistance to treatments. Our study relies on original observations from the team that dedifferentiated cells produce an abundant extracellular matrix (ECM) enriched in the lysyl oxidase-like 2 LOXL2, a collagen crosslinking enzyme also known to drive the epithelial-to-mesenchymal transition in breast cancer. Its role in melanoma biology remains poorly explored. We hypothesized that LOXL2 production by melanoma cells could influence their mesenchymal properties as well as ECM remodeling and tumor stiffness observed in vivo during adaptive response and therapeutic resistance.We first showed that LOXL2 is preferentially expressed by dedifferentiated melanoma cells and that its expression is associated with poor prognosis in melanoma. LOXL2 is induced by the combination of BRAF and MEK inhibitors or hypoxia, cues known to promote the transition towards a dedifferentiated phenotype, and regulated by the cell plasticity transcription factor ZEB1. Interestingly, LOXL2 induction by the targeted therapy is reversed by inhibition of the RTK and AKT pathways. We then investigated the specific contribution of LOXL2 to the dedifferentiated mesenchymal phenotype using loss-of-function approaches. We revealed that LOXL2 plays a role in focal adhesion formation and mesenchymal cell morphology, and promotes melanoma cell migration, invasion and metastasis. Mechanistically, comparative proteomic analysis identified the plasminogen activator inhibitor 2, PAI-2, a member of the serpin family, as a potential effector of LOXL2-mediated migration. Finally, we showed that targeting LOXL2 in dedifferentiated cells and melanoma-associated fibroblasts impairs their ability to contract a collagen matrix and assemble an organized ECM, suggesting the implication of LOXL2 in the dialogue between melanoma cells and the tumoral matrix.Taken together, these results establish an original link between LOXL2, melanoma cell phenotypic diversity and stromal matrix remodeling. Our study reveals that, in addition to its conventional role in collagen remodeling, LOXL2 exerts a tumor cell-autonomous pro-invasive action in melanoma. In addition, my work provides a better understanding of the ECM biomechanical signals that affect tumor cell plasticity and adaptation to anti-melanoma therapies, and highlights the value of targeting LOXL2 in the treatment of metastatic and resistant disease

Heart failure may be a consequence of ischemic or non-ischemic cardiomyopathy. Etiologies for LV systolic dysfunction in ischemic cardiomyopathy include; 1) transmural scar, 2) nontransmural scar, 3) repetitive myocardial stunning, 4) hibernating myocardium, and 5) remodeled myocardium. The LV remodeling process, which is activated by the renin-angiotensin system (RAS), stimulates toxic catecholamine actions and matrix metalloproteinases, resulting in maladaptive cellular and molecular alterations5, with a final pathway to interstitial fibrosis. These responses to LV dysfunction and interstitial fibrosis lead to progressive worsening of LV function. Established treatment options for ischemic cardiomyopathy include medical therapy, revascularization, and cardiac transplantation. While there has been continuous progress in the medical treatment of heart failure with beta-blockers, angiotensin-converting enzyme (ACE) inhibition, angiotensin II type 1 receptor (AT1R) blockers, and aldosterone to beneficially influence morbidity and mortality, the 5-years mortality rate for heart failure patients remains as high as 50%. Revascularization procedures include percutaneous transluminal coronary artery interventions (PCI) including angioplasty and endovascular stent placement and coronary artery bypass grafting (CABG). Whereas patents with heart failure due to non-coronary etiologies may best benefit from medical therapy or heart transplantation, coronary revascularization has the potential to improve ventricular function, symptoms, and long term survival, in patients with heart failure symptoms due to CAD and ischemic cardiomyopathy.